WorldWideScience

Sample records for honeybeenet forage region

  1. Dynamical Models of Interactions between Herds Forage and Water Resources in Sahelian Region

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    Jean Jules Tewa

    2014-01-01

    Full Text Available Optimal foraging is one of the capital topics nowadays in Sahelian region. The vast majority of feed consumed by ruminants in Sahelian region is still formed by natural pastures. Pastoral constraints are the high variability of available forage and drinking water in space and especially in time (highly seasonal, interannual variability and the scarcity of water resources. The mobility is the main functional and opportunistic adaptation to these constraints. Our goal in this paper is to formalize two dynamical models for interactions between a herd of domesticate animals, forage resources, and water resources inside a given Sahelian area, in order to confirm, explain, and predict by mathematical models some observations about pastoralism in Sahelian region. These models in some contexts can be similar to predator-prey models as forage and water resources can be considered as preys and herd’s animals as predators. These models exhibit very rich dynamics, since it predicts abrupt changes in consumer behaviour and disponibility of forage or water resources. The dynamics exhibits a possible coexistence between herd, resources, and water with alternative peaks in their trajectories.

  2. Wetland selection by breeding and foraging black terns in the Prairie Pothole Region of the United States

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    Steen, Valerie A.; Powell, Abby N.

    2012-01-01

    We examined wetland selection by the Black Tern (Chlidonias niger), a species that breeds primarily in the prairie pothole region, has experienced population declines, and is difficult to manage because of low site fidelity. To characterize its selection of wetlands in this region, we surveyed 589 wetlands throughout North and South Dakota. We documented breeding at 5% and foraging at 17% of wetlands. We created predictive habitat models with a machine-learning algorithm, Random Forests, to explore the relative role of local wetland characteristics and those of the surrounding landscape and to evaluate which characteristics were important to predicting breeding versus foraging. We also examined area-dependent wetland selection while addressing the passive sampling bias by replacing occurrence of terns in the models with an index of density. Local wetland variables were more important than landscape variables in predictions of occurrence of breeding and foraging. Wetland size was more important to prediction of foraging than of breeding locations, while floating matted vegetation was more important to prediction of breeding than of foraging locations. The amount of seasonal wetland in the landscape was the only landscape variable important to prediction of both foraging and breeding. Models based on a density index indicated that wetland selection by foraging terns may be more area dependent than that by breeding terns. Our study provides some of the first evidence for differential breeding and foraging wetland selection by Black Terns and for a more limited role of landscape effects and area sensitivity than has been previously shown.

  3. Intraspecific Variation among Social Insect Colonies: Persistent Regional and Colony-Level Differences in Fire Ant Foraging Behavior.

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    Alison A Bockoven

    Full Text Available Individuals vary within a species in many ecologically important ways, but the causes and consequences of such variation are often poorly understood. Foraging behavior is among the most profitable and risky activities in which organisms engage and is expected to be under strong selection. Among social insects there is evidence that within-colony variation in traits such as foraging behavior can increase colony fitness, but variation between colonies and the potential consequences of such variation are poorly documented. In this study, we tested natural populations of the red imported fire ant, Solenopsis invicta, for the existence of colony and regional variation in foraging behavior and tested the persistence of this variation over time and across foraging habitats. We also reared single-lineage colonies in standardized environments to explore the contribution of colony lineage. Fire ants from natural populations exhibited significant and persistent colony and regional-level variation in foraging behaviors such as extra-nest activity, exploration, and discovery of and recruitment to resources. Moreover, colony-level variation in extra-nest activity was significantly correlated with colony growth, suggesting that this variation has fitness consequences. Lineage of the colony had a significant effect on extra-nest activity and exploratory activity and explained approximately half of the variation observed in foraging behaviors, suggesting a heritable component to colony-level variation in behavior.

  4. Intraspecific Variation among Social Insect Colonies: Persistent Regional and Colony-Level Differences in Fire Ant Foraging Behavior.

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    Bockoven, Alison A; Wilder, Shawn M; Eubanks, Micky D

    2015-01-01

    Individuals vary within a species in many ecologically important ways, but the causes and consequences of such variation are often poorly understood. Foraging behavior is among the most profitable and risky activities in which organisms engage and is expected to be under strong selection. Among social insects there is evidence that within-colony variation in traits such as foraging behavior can increase colony fitness, but variation between colonies and the potential consequences of such variation are poorly documented. In this study, we tested natural populations of the red imported fire ant, Solenopsis invicta, for the existence of colony and regional variation in foraging behavior and tested the persistence of this variation over time and across foraging habitats. We also reared single-lineage colonies in standardized environments to explore the contribution of colony lineage. Fire ants from natural populations exhibited significant and persistent colony and regional-level variation in foraging behaviors such as extra-nest activity, exploration, and discovery of and recruitment to resources. Moreover, colony-level variation in extra-nest activity was significantly correlated with colony growth, suggesting that this variation has fitness consequences. Lineage of the colony had a significant effect on extra-nest activity and exploratory activity and explained approximately half of the variation observed in foraging behaviors, suggesting a heritable component to colony-level variation in behavior.

  5. Effects of irrigation on sorghum forage yield and quality in the central sands region of Wisconsin

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    A study was conducted to assess effects of irrigation on yield and quality of photoperiod sensitive (PS) and non-PS forage sorghum, sorghum-sudangrass, and sudangrass in comparison to corn in central Wisconsin. The study was a strip-plot design with a 5 x 8 factorial arrangement of treatments. Five ...

  6. Foraging behavior of selected insectivorous birds in Cauvery Delta region of Nagapattinam District, Tamil Nadu, India

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    S. Asokan

    2010-02-01

    Full Text Available This paper reports the foraging behavior of five insectivorous birds, namely White-breasted Kingfisher Halcyon smyrnensis, Small Bee-eater Merops orientalis, Indian Roller Coracias benghalensis, Common Myna Acridotheres tristis and Black Drongo Dicrurus macrocercus in Nagapattinam District of Tamil Nadu, India. The birds used a variety of perch types for hunting insect prey; in general the electric power line was a common perch type used by all species except the Common Myna. The perching and foraging height used by birds were classified into 3 meter categories, up to 12m. Aerial feeding or hawking in Bee-eaters and ground feeding in Common Mynas were major feeding techniques, recorded 68% and 86% of the time respectively. The other three species used gleaning as a feeding technique. The highest niche overlap was recorded between Indian Rollers and Black Drongos and between White-breasted Kingfishers and Indian Rollers.

  7. ENERGETIC VALUE OF FORAGES FROM SEMI-ARID REGION AND DIGESTIBILITY OF RATIONS FOR NAKED NECK PULLETS

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    ALEX MARTINS VARELA DE ARRUDA

    2014-01-01

    Full Text Available The feeding programs for naked neck chickens in semi-intensive production system from brazilian equatorial semi-arid environment, must consider regional food availability and respective nutritional values. Thus, to evaluate the digestibility and metabolizable energy of alternative forages, it was used 240 naked neck pullets (Isa Label lineage receiving water and ration ad libitum, pair-housed in cages for total collection of excreta on conventional warehouse. It was used a completely randomized design with factorial arrangement (5x2: one control ration (corn and soy meal and other four experimental rations with silk flower hay (Calotropis procera, cassava leafs hay (Manihot esculenta, kills pasture hay (Senna obtusifolia or leucaena leafs hay (Leucaena leucocephala, and all rations were balanced for two growing phases, between 8 and 10 weeks (young pullets and between 14 and 16 weeks of age (old pullets. The values of apparent digestibility of nutrients for all experimental rations were lower than control ration (P <0.05 and it was observed general means of 72.18% for dry matter, 78.12% for crude protein, 66.90% for ether extract, 28.08% for neutral detergent fiber, 18.51% for the acid detergent fiber, 71.64% for gross energy and availability of 15.61% for mineral matter. The general mean of apparent and corrected metabolizable energy of alternative forages was 1217 kcal/ kg and 1108 kcal/kg, respectively, and the higher value was determined for leucaena hay and the lower value for silk flower hay (P <0.05.

  8. Green turtles (Chelonia mydas) foraging at Arvoredo Island in Southern Brazil: Genetic characterization and mixed stock analysis through mtDNA control region haplotypes

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    2009-01-01

    We analyzed mtDNA control region sequences of green turtles (Chelonia mydas) from Arvoredo Island, a foraging ground in southern Brazil, and identified eight haplotypes. Of these, CM-A8 (64%) and CM-A5 (22%) were dominant, the remainder presenting low frequencies (Rocas/Noronha, in Brazil (p > 0.05). Mixed Stock Analysis, incorporating eleven Atlantic and one Mediterranean rookery as possible sources of individuals, indicated Ascension and Aves islands as the main contributing stocks to the Arvoredo aggregation (68.01% and 22.96%, respectively). These results demonstrate the extensive relationships between Arvoredo Island and other Atlantic foraging and breeding areas. Such an understanding provides a framework for establishing adequate management and conservation strategies for this endangered species. PMID:21637527

  9. Green turtles (Chelonia mydas foraging at Arvoredo Island in Southern Brazil: genetic characterization and mixed stock analysis through mtDNA control region haplotypes

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    Maíra Carneiro Proietti

    2009-01-01

    Full Text Available We analyzed mtDNA control region sequences of green turtles (Chelonia mydas from Arvoredo Island, a foraging ground in southern Brazil, and identified eight haplotypes. Of these, CM-A8 (64% and CM-A5 (22% were dominant, the remainder presenting low frequencies ( 0.05. Mixed Stock Analysis, incorporating eleven Atlantic and one Mediterranean rookery as possible sources of individuals, indicated Ascension and Aves islands as the main contributing stocks to the Arvoredo aggregation (68.01% and 22.96%, respectively. These results demonstrate the extensive relationships between Arvoredo Island and other Atlantic foraging and breeding areas. Such an understanding provides a framework for establishing adequate management and conservation strategies for this endangered species.

  10. Green turtles (Chelonia mydas) foraging at Arvoredo Island in Southern Brazil: Genetic characterization and mixed stock analysis through mtDNA control region haplotypes.

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    Proietti, Maíra Carneiro; Lara-Ruiz, Paula; Reisser, Júlia Wiener; da Silva Pinto, Luciano; Dellagostin, Odir Antonio; Marins, Luis Fernando

    2009-07-01

    We analyzed mtDNA control region sequences of green turtles (Chelonia mydas) from Arvoredo Island, a foraging ground in southern Brazil, and identified eight haplotypes. Of these, CM-A8 (64%) and CM-A5 (22%) were dominant, the remainder presenting low frequencies ( 0.05). Mixed Stock Analysis, incorporating eleven Atlantic and one Mediterranean rookery as possible sources of individuals, indicated Ascension and Aves islands as the main contributing stocks to the Arvoredo aggregation (68.01% and 22.96%, respectively). These results demonstrate the extensive relationships between Arvoredo Island and other Atlantic foraging and breeding areas. Such an understanding provides a framework for establishing adequate management and conservation strategies for this endangered species.

  11. Matching forage systems with cow size and environment for sustainable cow-calf production in the southern region

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    There has been increased interest in intensification of cow-calf production due to an increasing world population and red meat demand along with reductions in available grazing lands. Intensified production can come about by increasing fertilization, supplementation, or feeding of stored forages, bu...

  12. Fine-scale recognition and use of mesoscale fronts by foraging Cape gannets in the Benguela upwelling region

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    Sabarros, Philippe S.; Grémillet, David; Demarcq, Hervé; Moseley, Christina; Pichegru, Lorien; Mullers, Ralf H. E.; Stenseth, Nils C.; Machu, Eric

    2014-09-01

    Oceanic structures such as mesoscale fronts may become hotspots of biological activity through concentration and enrichment processes. These fronts generally attract fish and may therefore be targeted by marine top-predators. In the southern Benguela upwelling system, such fronts might be used as environmental cues by foraging seabirds. In this study we analyzed high-frequency foraging tracks (GPS, 1 s sampling) of Cape gannets Morus capensis from two colonies located on the west and east coast of South Africa in relation to mesoscale fronts detected on daily high-resolution chlorophyll-a maps (MODIS, 1 km). We tested the association of (i) searching behavior and (ii) diving activity of foraging birds with mesoscale fronts. We found that Cape gannets shift from transiting to area-restricted search mode (ARS) at a distance from fronts ranging between 2 and 11 km (median is 6.7 km). This suggests that Cape gannets may be able to sense fronts (smell or vision) or other predators, and that such detection triggers an intensified investigation of their surroundings (i.e. ARS). Also we found that diving probability increases near fronts in 11 out of 20 tracks investigated (55%), suggesting that Cape gannets substantially use fronts for feeding; in the remaining cases (45%), birds may have used other cues for feeding including fishing vessels, particularly for gannets breeding on the west coast. We demonstrated in this study that oceanographic structures such as mesoscale fronts are important environmental cues used by a foraging seabird within the rich waters of an upwelling system. There is now need for further investigations on how Cape gannets actually detect these fronts.

  13. Effects of forage type, body condition and single-nucleotide polymorphisms in the bovine cytochrome P450 regulatory region on cow productivity.

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    Sales, M A; Murphy, K Y; Reiter, S T; Brown, A H; Brown, M A; Looper, M L; Rosenkrans, C F

    2013-02-01

    Single-nucleotide polymorphisms (SNP) in the coding sequence of cytochrome p450 (CYP3A28) have been associated with milk yield and composition, and calving traits in cows. In this study, we aimed to determine whether (i) the CYP3A28 regulatory region was polymorphic and (ii) SNP genotype, forage type, body condition and their interactions affect cow productivity. Primers for CYP3A28 promoter were designed to amplify a 483-bp segment by PCR. Amplicon sequences revealed seven SNP (T-318C, T-113A, C-189T, T-78G, A6G, G17A and T21C) in Brahman (38 cows), Brahman x Angus reciprocal crosses (47 cows) and crossbreds (98 cows). Angus cows (n = 41) appeared to be fixed at those SNP locations. Genotype and forage {endophyte-infected tall fescue [KY+; Lolium arundinaceum (Schreb.) S. J. Darbyshire] vs. bermudagrass [Cynodon dactylon (L.) Pers.]} effects on lifetime (8-years) calving rate, and calf weaning weights and heights were determined in Herd 1 (126 cows); genotype and BC (low vs. moderate) effects on calving date and calving percent were determined in Herd 2 (98 cows). Four SNP (T-318C, T-113A, A06G and T21C) appeared to be related to cattle productivity, CC cows at T-318C having a lower (p KY+ and were TT at T-318C produced calves that tended (p < 0.07) to weigh less than their contemporaries. Moreover, calves of TT cows were shorter (p < 0.05) at weaning than calves of CC or TC cows. In Herd 2, moderate-BC cows that were TT or AA at T-318C, T-113A, T-78G, A6G and T21C had greater (p < 0.05) calving rates (74-80%) than heterozygous cows (46-60%), and low-BC cows that were AA at G17A calved at least 6 days earlier (p < 0.05) than heterozygous cows. Our findings suggest that SNP in the CYP3A28 regulatory region of Brahman-influenced cows are associated with cattle productivity.

  14. Determining spatio-temporal distribution of bee forage species of Al-Baha region based on ground inventorying supported with GIS applications and Remote Sensed Satellite Image analysis.

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    Adgaba, Nuru; Alghamdi, Ahmed; Sammoud, Rachid; Shenkute, Awraris; Tadesse, Yilma; Ansari, Mahammad J; Sharma, Deepak; Hepburn, Colleen

    2017-07-01

    In arid zones, the shortage of bee forage is critical and usually compels beekeepers to move their colonies in search of better forages. Identifying and mapping the spatiotemporal distribution of the bee forages over given area is important for better management of bee colonies. In this study honey bee plants in the target areas were inventoried following, ground inventory work supported with GIS applications. The study was conducted on 85 large plots of 50 × 50 m each. At each plot, data on species name, height, base diameter, crown height, crown diameter has been taken for each plant with their respective geographical positions. The data were stored, and processed using Trimble GPS supported with ArcGIS10 software program. The data were used to estimate the relative frequency, density, abundance and species diversity, species important value index and apicultural value of the species. In addition, Remotely Sensed Satellite Image of the area was obtained and processed using Hopfield Artificial Neural Network techniques. During the study, 182 species from 49 plant families were identified as bee forages of the target area. From the total number of species; shrubs, herbs and trees were accounting for 61%, 27.67%, and 11.53% respectively. Of which Ziziphus spina-christi, Acacia tortilis, Acacia origina, Acacia asak, Lavandula dentata, and Hypoestes forskaolii were the major nectar source plants of the area in their degree of importance. The average vegetation cover values of the study areas were low (place. The Remote Sensed Satellite Image analysis confirmed the spatial distribution of the bee forage resources as determined by the ground inventory work. An integrated approach, combining the ground inventory work with GIS and satellite image processing techniques could be an important tool for characterizing and mapping the available bee forage resources leading to their efficient and sustainable utilization.

  15. Determining spatio-temporal distribution of bee forage species of Al-Baha region based on ground inventorying supported with GIS applications and Remote Sensed Satellite Image analysis

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    Nuru Adgaba

    2017-07-01

    Full Text Available In arid zones, the shortage of bee forage is critical and usually compels beekeepers to move their colonies in search of better forages. Identifying and mapping the spatiotemporal distribution of the bee forages over given area is important for better management of bee colonies. In this study honey bee plants in the target areas were inventoried following, ground inventory work supported with GIS applications. The study was conducted on 85 large plots of 50 × 50 m each. At each plot, data on species name, height, base diameter, crown height, crown diameter has been taken for each plant with their respective geographical positions. The data were stored, and processed using Trimble GPS supported with ArcGIS10 software program. The data were used to estimate the relative frequency, density, abundance and species diversity, species important value index and apicultural value of the species. In addition, Remotely Sensed Satellite Image of the area was obtained and processed using Hopfield Artificial Neural Network techniques. During the study, 182 species from 49 plant families were identified as bee forages of the target area. From the total number of species; shrubs, herbs and trees were accounting for 61%, 27.67%, and 11.53% respectively. Of which Ziziphus spina-christi, Acacia tortilis, Acacia origina, Acacia asak, Lavandula dentata, and Hypoestes forskaolii were the major nectar source plants of the area in their degree of importance. The average vegetation cover values of the study areas were low (<30% with low Shannon’s species diversity indices (H′ of 0.5–1.52 for different sites. Based on the eco-climatological factors and the variations in their flowering period, these major bee forage species were found to form eight distinct spatiotemporal categories which allow beekeepers to migrate their colonies to exploit the resources at different seasons and place. The Remote Sensed Satellite Image analysis confirmed the spatial

  16. Afferent Connections to the Rostrolateral Part of the Periaqueductal Gray: A Critical Region Influencing the Motivation Drive to Hunt and Forage

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    Sandra Regina Mota-Ortiz

    2009-01-01

    Full Text Available Previous studies have shown that a particular site in the periaqueductal gray (PAG, the rostrolateral PAG, influences the motivation drive to forage or hunt. To have a deeper understanding on the putative paths involved in the decision-making process between foraging, hunting, and other behavioral responses, in the present investigation, we carried out a systematic analysis of the neural inputs to the rostrolateral PAG (rlPAG, using Fluorogold as a retrograde tracer. According to the present findings, the rlPAG appears to be importantly driven by medial prefrontal cortical areas involved in controlling attention-related and decision-making processes. Moreover, the rlPAG also receives a wealth of information from different amygdalar, hypothalamic, and brainstem sites related to feeding, drinking, or hunting behavioral responses. Therefore, this unique combination of afferent connections puts the rlPAG in a privileged position to influence the motivation drive to choose whether hunting and foraging would be the most appropriate adaptive responses.

  17. Foraging Experiences with Children

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    Russell, Helen Ross

    1976-01-01

    Provided are foraging experiences and wild foods information for utilization in the urban school curriculum. Food uses are detailed for roses, dandelions, wild onions, acorns, cattails, violets and mints. (BT)

  18. Habitat-specific foraging strategies in Australasian gannets

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    Melanie R. Wells

    2016-07-01

    Full Text Available Knowledge of top predator foraging adaptability is imperative for predicting their biological response to environmental variability. While seabirds have developed highly specialised techniques to locate prey, little is known about intraspecific variation in foraging strategies with many studies deriving information from uniform oceanic environments. Australasian gannets (Morus serrator typically forage in continental shelf regions on small schooling prey. The present study used GPS and video data loggers to compare habitat-specific foraging strategies at two sites of contrasting oceanographic regimes (deep water near the continental shelf edge, n=23; shallow inshore embayment, n=26, in south-eastern Australia. Individuals from the continental shelf site exhibited pelagic foraging behaviours typical of gannet species, using local enhancement to locate and feed on small schooling fish; in contrast only 50% of the individuals from the inshore site foraged offshore, displaying the typical pelagic foraging strategy. The remainder adopted a strategy of searching sand banks in shallow inshore waters in the absence of conspecifics and other predators for large, single prey items. Furthermore, of the individuals foraging inshore, 93% were male, indicating that the inshore strategy may be sex-specific. Large inter-colony differences in Australasian gannets suggest strong plasticity in foraging behaviours, essential for adapting to environmental change.

  19. Habitat-specific foraging strategies in Australasian gannets.

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    Wells, Melanie R; Angel, Lauren P; Arnould, John P Y

    2016-07-15

    Knowledge of top predator foraging adaptability is imperative for predicting their biological response to environmental variability. While seabirds have developed highly specialised techniques to locate prey, little is known about intraspecific variation in foraging strategies with many studies deriving information from uniform oceanic environments. Australasian gannets (Morus serrator) typically forage in continental shelf regions on small schooling prey. The present study used GPS and video data loggers to compare habitat-specific foraging strategies at two sites of contrasting oceanographic regimes (deep water near the continental shelf edge, n=23; shallow inshore embayment, n=26), in south-eastern Australia. Individuals from the continental shelf site exhibited pelagic foraging behaviours typical of gannet species, using local enhancement to locate and feed on small schooling fish; in contrast only 50% of the individuals from the inshore site foraged offshore, displaying the typical pelagic foraging strategy. The remainder adopted a strategy of searching sand banks in shallow inshore waters in the absence of conspecifics and other predators for large, single prey items. Furthermore, of the individuals foraging inshore, 93% were male, indicating that the inshore strategy may be sex-specific. Large inter-colony differences in Australasian gannets suggest strong plasticity in foraging behaviours, essential for adapting to environmental change.

  20. Through the stomach of a predator: Regional patterns of forage in the diet of albacore tuna in the California Current System and metrics needed for ecosystem-based management

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    Glaser, Sarah M.; Waechter, Katrina E.; Bransome, Nicole C.

    2015-06-01

    Foraging habits of predators can reveal patterns in prey ecology and guide ecosystem-based management by informing species interactions. This study describes the diet habits of albacore tuna in three regions (north, central, south) of the California Current System (CCS) and estimates the total predation mortality imposed on twenty prey taxa. The northern CCS was defined by predation on decapods, euphausiids, anchovy and hake. The central CCS was defined by predation on squid, hake and Pacific saury. The southern CCS was defined by predation on anchovy. We estimate North Pacific albacore consumed each year, on average, 54,000 mt of decapods and euphausiids, 43,000 mt of cephalopods, 84,000 mt of juvenile hake, 1600 mt of myctophids, 21,000 mt of juvenile sardine, 10,000 mt of juvenile rockfishes, almost 43,000 mt of Pacific saury, and over 107,000 mt of juvenile anchovy. While variability in predation certainly exists, this and prior studies show that diet habits of albacore are fairly stable through time. The northern CCS appears to be a more significant source of energy for albacore. When designing ecosystem-based approaches to the management of CCS-based fisheries, we recommend that the forage contribution of saury, hake and anchovy to the albacore population be considered.

  1. Adaptive Bacterial Foraging Optimization

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    Hanning Chen

    2011-01-01

    Full Text Available Bacterial Foraging Optimization (BFO is a recently developed nature-inspired optimization algorithm, which is based on the foraging behavior of E. coli bacteria. Up to now, BFO has been applied successfully to some engineering problems due to its simplicity and ease of implementation. However, BFO possesses a poor convergence behavior over complex optimization problems as compared to other nature-inspired optimization techniques. This paper first analyzes how the run-length unit parameter of BFO controls the exploration of the whole search space and the exploitation of the promising areas. Then it presents a variation on the original BFO, called the adaptive bacterial foraging optimization (ABFO, employing the adaptive foraging strategies to improve the performance of the original BFO. This improvement is achieved by enabling the bacterial foraging algorithm to adjust the run-length unit parameter dynamically during algorithm execution in order to balance the exploration/exploitation tradeoff. The experiments compare the performance of two versions of ABFO with the original BFO, the standard particle swarm optimization (PSO and a real-coded genetic algorithm (GA on four widely-used benchmark functions. The proposed ABFO shows a marked improvement in performance over the original BFO and appears to be comparable with the PSO and GA.

  2. Cooperative Bacterial Foraging Optimization

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    Hanning Chen

    2009-01-01

    Full Text Available Bacterial Foraging Optimization (BFO is a novel optimization algorithm based on the social foraging behavior of E. coli bacteria. This paper presents a variation on the original BFO algorithm, namely, the Cooperative Bacterial Foraging Optimization (CBFO, which significantly improve the original BFO in solving complex optimization problems. This significant improvement is achieved by applying two cooperative approaches to the original BFO, namely, the serial heterogeneous cooperation on the implicit space decomposition level and the serial heterogeneous cooperation on the hybrid space decomposition level. The experiments compare the performance of two CBFO variants with the original BFO, the standard PSO and a real-coded GA on four widely used benchmark functions. The new method shows a marked improvement in performance over the original BFO and appears to be comparable with the PSO and GA.

  3. Redesigning forages with condensed tannins

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    Maximizing protein content in forages and minimizing protein loss during silage fermentation and rumen digestion are concerns for livestock and dairy producers. Substantial amounts of forage protein undergo proteolysis (breakdown) during the ensiling process and during rumen fermentation, transforme...

  4. Optimal Foraging in Semantic Memory

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    Hills, Thomas T.; Jones, Michael N.; Todd, Peter M.

    2012-01-01

    Do humans search in memory using dynamic local-to-global search strategies similar to those that animals use to forage between patches in space? If so, do their dynamic memory search policies correspond to optimal foraging strategies seen for spatial foraging? Results from a number of fields suggest these possibilities, including the shared…

  5. Adaptability evaluation of 12 perennial forage cultivars in alpine region of Diqing%12个多年生牧草品种在迪庆高寒地区的引种评价

    Institute of Scientific and Technical Information of China (English)

    单贵莲; 张美艳; 廖祥龙; 钟绍丽; 周鹏; 薛世明

    2016-01-01

    为筛选出适宜云南迪庆高寒地区种植的多年生牧草品种,本研究开展了12个多年生牧草品种引种适应性的比较,并采用灰色关联度综合评价法对其生产性能进行了综合评价.结果表明,12种牧草生产性能的高低顺序为紫花苜蓿牧歌401+Z(Medicago sativa cv.Amerigraze401+Z)>菊苣将军(Cichorium intybus cv.Commander)>鸭茅安巴(Dactylis glomerata cv.Anmba)>多年生黑麦草雅晴(Lolium perenne cv.Yatsyn)>白三叶铺地(Trifolium repens cv.Prop)>红三叶(T.pratense)>白三叶海法(T.repens cv.Haifa)>紫花苜蓿游客(Medicago sativa cv.Eureka)>紫花苜蓿 WL-525(Medicago sativa cv.WL-525)>扁穗雀麦草地麦特(Bromus catharticus cv.Grasslands Matua)>紫花苜蓿猎人河(M.sativa cv.Hunterriver)>老芒麦同德(Elymus sibiricus cv.Tongde).其中,牧歌401+Z紫花苜蓿、将军菊苣、安巴鸭茅、雅晴多年生黑麦草、铺地白三叶、普通红三叶、海法白三叶在当地适应性较好,生产性能相对较高,可作为当地建植栽培草地及改良天然草地的优选品种.研究结果对解决当地饲草匮乏、促进当地草地畜牧业的可持续发展具有重要的意义.%To select suitable perennial forages cultivating in alpine region of Diqing,the introduction adaptabili-ty of 1 2 perennial forage grasses was studied in this research,and the grey correlative degree analysis was used to evaluate the production performance of these 1 2 perennial forage grasses.The results showed that the order of production performance of 12 perennial forage grasses was Medicago sativa cv.Amerigraze401+Z >Cicho-rium intybus cv.Commander > Dactylis glomerata cv.Anmba > Lolium perenne cv.Yatsyn > Trifolium repens cv.Prop > Trifolium pratense > T.repens cv.Haifa > M.sativa cv.Eureka > M.sativa cv. WL-525 >Bromus willdenowii cv.Grasslands Matua >M.sativa cv.Hunterriver >Elymus sibiricus cv. Tongde.The production and adaptability of M.sativa cv

  6. FORAGE AND GRAIN YIELD PERFORMANCES OF SOYBEAN LINES

    Directory of Open Access Journals (Sweden)

    Ugur BILGILI

    2006-05-01

    Full Text Available Field experiments were conducted to evaluate the yield and yield components of twelve soybean genotypes as a forage and a grain crop in Marmara Region of Turkey in 2003-2004 growing seasons. Forage and dry matter yield and yield components at one vegetative stage (V5 and two reproductive stages (R2, and R4 and seed yield was determined in all soybean genotypes. The experiments showed that the harvest stages had signifi cant effects on forage and dry matter yield, and R4 reproductive stage had the highest forage and dry matter yield. Dry matter partitioning of soybean plant parts was greatly affected by harvest stages, while the genotypes had little effect on dry matter partitioning of soybean plant parts. There were statistically signifi cant differences between soybean genotypes in seed yield, but the differences were small. The correlations between forage and dry matter yield and seed yield were not statistically signifi cant.

  7. Identifying robustness in the regulation of collective foraging of ant colonies using an interaction-based model with backward bifurcation.

    Science.gov (United States)

    Udiani, Oyita; Pinter-Wollman, Noa; Kang, Yun

    2015-02-21

    Collective behaviors in social insect societies often emerge from simple local rules. However, little is known about how these behaviors are dynamically regulated in response to environmental changes. Here, we use a compartmental modeling approach to identify factors that allow harvester ant colonies to regulate collective foraging activity in response to their environment. We propose a set of differential equations describing the dynamics of: (1) available foragers inside the nest, (2) active foragers outside the nest, and (3) successful returning foragers, to understand how colony-specific parameters, such as baseline number of foragers, interactions among foragers, food discovery rates, successful forager return rates, and foraging duration might influence collective foraging dynamics, while maintaining functional robustness to perturbations. Our analysis indicates that the model can undergo a forward (transcritical) bifurcation or a backward bifurcation depending on colony-specific parameters. In the former case, foraging activity persists when the average number of recruits per successful returning forager is larger than one. In the latter case, the backward bifurcation creates a region of bistability in which the size and fate of foraging activity depends on the distribution of the foraging workforce among the model's compartments. We validate the model with experimental data from harvester ants (Pogonomyrmex barbatus) and perform sensitivity analysis. Our model provides insights on how simple, local interactions can achieve an emergent and robust regulatory system of collective foraging activity in ant colonies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. The Dynamics of Foraging Ants

    Science.gov (United States)

    Baxter, G. William

    2009-03-01

    We experimentally study the foraging of small black ants, Formicinae lasius flavus, in order to describe their foraging behavior mathematically. Individual ants are allowed to forage on a two-dimensional surface in the absence of any food sources. The position of the ant as a function of time is determined using a high-resolution digital camera. Analysis of the average square displacements of many ants suggests that the foraging strategy is a non-reversing random walk. Moreover, the ants do not retrace their steps to return home but instead continue the random walk until it brings them back near their starting point.

  9. Collective foraging in heterogeneous landscapes

    CERN Document Server

    Bhattacharya, Kunal

    2013-01-01

    Animals foraging alone are hypothesized to optimize the encounter rates with resources through L\\'evy walks. However, the issue of how the interactions between multiple foragers influence their search efficiency is still not completely understood. To address this, we consider a model to study the optimal strategy for a group of foragers searching for targets distributed heterogeneously. In our model foragers move on a square lattice containing immobile but regenerative targets. At any instant a forager is able to detect only those targets that happen to be in the same site. However, we allow the foragers to have information about the state of other foragers. A forager who has not detected any target walks towards the nearest location, where another forager has detected a target, with probability $\\exp{\\left(-\\alpha d\\right)}$, where $d$ is the distance and $\\alpha$ is a parameter. The model reveals that neither overcrowding ($\\alpha\\to 0$) nor independent searching ($\\alpha\\to\\infty$) is beneficial for the gr...

  10. Introduction experiment of leguminous forages in the dry and hot valley of Yuanmou region%元谋干热河谷豆科牧草的引种试验

    Institute of Scientific and Technical Information of China (English)

    龙会英; 张德; 朱红业; 金杰; 史亮涛; 张明忠

    2011-01-01

    2003—2006年元谋干热河谷对16个豆科牧草进行引种试验,结果表明,参试材料中,除蝴碟豆(Centrosemapubescens)、大叶千斤拔(Flemingiamacrophylla)和卵叶山蚂蝗(Desmodiumovalifolium)由于气候差异性不能结实外,其他牧草均能适应该地区种植。其中,银合欢属表现出产量高、叶量大、适口性好等特点。产量排列前3名的牧草为银合欢(Leucaenaleucocephala)K636、新银合欢和热研1号银合欢,干草产量分别为26933.9、24882.6和22%An experiment was conducted to select the suibtable plant legume forages from 16 legume fora ges for the dry and hot valley in the Yuanmou region. This study showed that Centrosema pubescens, Flemingia macropylla, and Desmodium ovalifolium did not seed and the other 13 plant species grew well. Leucaena leucocephala showed the highest yield with a lange number of leaves and good palatability. The top yield was L. leucocephala K636, L. leucocephala, L. leucocephala cv. Reyan No. 1 with 26 93a. 9 kg/ha, 24 882.6 kg/ha, 22 459.2 kg/ha, respectively. The sheep preference for these plants was 5. The Neotononis wightii cv. Tinarroo, Acacia farnesiana and Sesbania grandiflora came to the second due to higher yield and good palatability, and ratio of dry weight to fresh weight and stem/leaf ratio of N. wightii cv. Tinarroo was 0.27 and 0.73. The lowest yield forage was Desmodium ovalifolium with 920.8 kg/ha, and its DW/FW ratio was 1.96. This study suggested that D. ovalifolium was not suitable to be planted in Yuanmou region; and the pest control for Cratylia argentea should be taken during its bloomin5 period to increase pod numbers.

  11. Personality, foraging and fitness consequences in a long lived seabird.

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    Samantha C Patrick

    Full Text Available While personality differences in animals are defined as consistent behavioural variation between individuals, the widely studied field of foraging specialisation in marine vertebrates has rarely been addressed within this framework. However there is much overlap between the two fields, both aiming to measure the causes and consequences of consistent individual behaviour. Here for the first time we use both a classic measure of personality, the response to a novel object, and an estimate of foraging strategy, derived from GPS data, to examine individual personality differences in black browed albatross and their consequences for fitness. First, we examine the repeatability of personality scores and link these to variation in foraging habitat. Bolder individuals forage nearer the colony, in shallower regions, whereas shyer birds travel further from the colony, and fed in deeper oceanic waters. Interestingly, neither personality score predicted a bird's overlap with fisheries. Second, we show that both personality scores are correlated with fitness consequences, dependent on sex and year quality. Our data suggest that shyer males and bolder females have higher fitness, but the strength of this relationship depends on year quality. Females who forage further from the colony have higher breeding success in poor quality years, whereas males foraging close to the colony always have higher fitness. Together these results highlight the potential importance of personality variation in seabirds and that the fitness consequences of boldness and foraging strategy may be highly sex dependent.

  12. Breeding tropical forages

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    L Jank

    2011-01-01

    Full Text Available Brazil has the largest commercial beef cattle herd and is the main beef exporter in the world. Cultivated pastures arethe basis for the Brazilian beef production, and occupy an area of 101.4 million hectares. However, very few forage cultivars arecommercially available, and the majority of these are of apomictic reproduction, thus genetically homogeneous. Tropical foragebreeding is at its infancy, but much investment and efforts have been applied in the last three decades and some new cultivars havebeen released. In this paper, origin of different species, modes of reproduction, breeding programs and targets are discussed andthe resulting new cultivars released are presented.

  13. Individual foraging strategies reveal niche overlap between endangered galapagos pinnipeds.

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    Stella Villegas-Amtmann

    Full Text Available Most competition studies between species are conducted from a population-level approach. Few studies have examined inter-specific competition in conjunction with intra-specific competition, with an individual-based approach. To our knowledge, none has been conducted on marine top predators. Sympatric Galapagos fur seals (Arctocephalus galapagoensis and sea lions (Zalophus wollebaeki share similar geographic habitats and potentially compete. We studied their foraging niche overlap at Cabo Douglas, Fernandina Island from simultaneously collected dive and movement data to examine spatial and temporal inter- and intra-specific competition. Sea lions exhibited 3 foraging strategies (shallow, intermediate and deep indicating intra-specific competition. Fur seals exhibited one foraging strategy, diving predominantly at night, between 0-80 m depth and mostly at 19-22 h. Most sea lion dives also occurred at night (63%, between 0-40 m, within fur seals' diving depth range. 34% of sea lions night dives occurred at 19-22 h, when fur seals dived the most, but most of them occurred at dawn and dusk, when fur seals exhibited the least amount of dives. Fur seals and sea lions foraging behavior overlapped at 19 and 21 h between 0-30 m depths. Sea lions from the deep diving strategy exhibited the greatest foraging overlap with fur seals, in time (19 h, depth during overlapping time (21-24 m, and foraging range (37.7%. Fur seals foraging range was larger. Cabo Douglas northwest coastal area, region of highest diving density, is a foraging "hot spot" for both species. Fur seals and sea lions foraging niche overlap occurred, but segregation also occurred; fur seals primarily dived at night, while sea lions exhibited night and day diving. Both species exploited depths and areas exclusive to their species. Niche breadth generally increases with environmental uncertainty and decreased productivity. Potential competition between these species could be greater during

  14. Spatial memory in foraging games.

    Science.gov (United States)

    Kerster, Bryan E; Rhodes, Theo; Kello, Christopher T

    2016-03-01

    Foraging and foraging-like processes are found in spatial navigation, memory, visual search, and many other search functions in human cognition and behavior. Foraging is commonly theorized using either random or correlated movements based on Lévy walks, or a series of decisions to remain or leave proximal areas known as "patches". Neither class of model makes use of spatial memory, but search performance may be enhanced when information about searched and unsearched locations is encoded. A video game was developed to test the role of human spatial memory in a canonical foraging task. Analyses of search trajectories from over 2000 human players yielded evidence that foraging movements were inherently clustered, and that clustering was facilitated by spatial memory cues and influenced by memory for spatial locations of targets found. A simple foraging model is presented in which spatial memory is used to integrate aspects of Lévy-based and patch-based foraging theories to perform a kind of area-restricted search, and thereby enhance performance as search unfolds. Using only two free parameters, the model accounts for a variety of findings that individually support competing theories, but together they argue for the integration of spatial memory into theories of foraging.

  15. Attention in Urban Foraging

    Directory of Open Access Journals (Sweden)

    Malcolm McCullough

    2013-05-01

    Full Text Available This position paper argues how there has to be much more to smart city learning than just wayshowing, and something better as augmented reality than covering the world with instructions. Attention has become something for many people to know better in an age of information superabundance. Embodied cognition explains how the work-ings of attention are not solely a foreground task, as if attention is something to pay. As digital media appear in ever more formats and contexts, their hybrids with physical form increasing influence how habitual engagement with persistent situations creates learning. Ambient information can just add to the distraction by multitasking, or it can support more favorable processes of shifting among different kinds of information with a particular intent. As one word for this latter process, foraging deserves more consideration in smart city learning

  16. Paleopathological description and diagnosis of metastatic carcinoma in an Early Bronze Age (4588+34 Cal. BP) forager from the Cis-Baikal region of Eastern Siberia.

    Science.gov (United States)

    Lieverse, Angela R; Temple, Daniel H; Bazaliiskii, Vladimir I

    2014-01-01

    Extensive osteolytic and osteoblastic lesions were observed on the skeletal remains of an adult male excavated from an Early Bronze Age cemetery dated to 4556+32 years BP, located in the Cis-Baikal region of Siberia (Russian Federation). Lytic lesions ranged in size from several mm to over 60 mm in diameter and had irregular, moth-eaten borders. Many of these lesions destroyed trabecular bone, though a hollowed shell of cortical bone often remained observable. Radiographic analysis revealed numerous lytic lesions within trabecular bone that had not yet affected the cortex. Blastic lesions were identified as spiculated lines, bands, or nodules of mostly immature (woven) bone formed at irregular intervals. Anatomical elements with the greatest involvement included those of the axial skeleton (skull, vertebrae, sacrum, ribs, and sternum) as well as proximal appendicular elements (ossa coxae, proximal femora, clavicles, scapulae, and proximal humeri). Osteocoalescence of destructive foci was observed on the ilium and frontal bone, with the largest lesion found on the right ilium. Differential diagnoses include metastatic carcinoma, mycotic infections, tuberculosis, Langerhan's cell histiocytosis, and multiple myeloma. Based on lesion appearance and distribution, age and sex of the individual, as well as pathogen endemism, the most likely diagnostic option for this set of lesions is metastatic carcinoma. The age and sex of this individual and appearance of the lesions may reflect carcinoma of the lung or, possibly, prostate. This represents one of the earliest cases of metastatic carcinoma worldwide and the oldest case documented thus far from Northeast Asia.

  17. Long bone cross-sectional geometric properties of Later Stone Age foragers and herder�foragers

    Directory of Open Access Journals (Sweden)

    Michelle E. Cameron

    2014-09-01

    Full Text Available Diaphyseal cross-sectional geometry can be used to infer activity patterns in archaeological populations. We examined the cross-sectional geometric (CSG properties of adult Later Stone Age (LSA herder-forager long bones from the inland lower Orange River Valley of South Africa (n=5 m, 13 f. We then compared their CSG properties to LSA forager adults from the coastal fynbos (n=23 m, 14 f and forest (n=17 m, 19 f regions, building on a previous report (Stock and Pfeiffer, 2004. The periosteal mould method was used to quantify total subperiosteal area, torsional strength, bilateral asymmetry and diaphyseal circularity (Imax/Imin at the mid-distal (35% location of upper arms (humeri and the mid-shaft (50% location of upper legs (femora. Maximum humerus and femur lengths were similar among the three samples, suggesting that adult stature was similar in all three regions. When compared to the previous study, CSG property values obtained using the periosteal mould method correlated well, and there were no significant differences between data collected using the different methods. No statistically significant differences were found among the humerus or femur CSG properties from the different regions. This finding suggests that all individuals undertook similar volitional habitual activities in regard to their upper limbs, and also had similar degrees of terrestrial mobility. These results indicate relative behavioural homogeneity among LSA foragers and herder foragers from South Africa. The small degree of regional variation apparent among the three samples may reflect local ecology and the subsistence demands affecting populations in these different regions.

  18. Forage maize nutritional quality according to organic and inorganic fertilization

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    Alejandro Moreno-Reséndez

    2017-01-01

    Full Text Available The research was conducted on a commercial land plot from the ejido Granada, municipality of M atamoros, Coahuila, situated inside the Comarca Lagunera, from April to August 2015, in order to establish the effect of two fertilization sources – organic and inorganic, upon the nutritional quality of forage maize during the spring - summer cycle with a r andomized block experimental design. T 1 = Acadian soil +Acadian foliage (marine algae extracts and T 2 = Regional control, with 16 replications. The evaluated variables were the nutritional quality of forage maize and the milk production (L•t - 1 dry matter an d L•ha - 1 . Due to the effect of the evaluated treatments, statistical differences were registered, both for, nutritional values of forage maize, such as: neutral and acid detergent fiber, non - fiber carbohydrates, total digestible nutrients, total net energ y for lactation and for milk production, in favor of organic fertilization. Therefore, it can be concluded that fertilizers of marine origin applied to forage maize increased both nutritional quality of forage maize and milk yield per ton of dry matter and per hectare of this forage.

  19. Forage based animal production systems and sustainability, an invited keynote

    Directory of Open Access Journals (Sweden)

    Abdul Shakoor Chaudhry

    2008-07-01

    Full Text Available Forages are essential for the successful operation of animal production systems. This is more relevant to ruminants which are heavily dependant upon forages for their health and production in a cost-effective and sustainable manner. While forages are an economical source of nutrients for animal production, they also help conserve the soil integrity, water supply and air quality. Although the role of these forages for animal production could vary depending upon the regional preferences for the animal and forage species, climate and resources, their importance in the success of ruminant production is acknowledged. However with the increasing global human population and urbanisation, the sustainability of forage based animal production systems is sometimes questioned due to the interrelationship between animal production and the environment. It is therefore vital to examine the suitability of these systems for their place in the future to supply quality food which is safe for human consumption and available at a competitive price to the growing human population. Grassland and forage crops are recognised for their contribution to the environment, recreation and efficiency of meat and milk production,. To maintain sustainability, it is crucial that such farming systems remain profitable and environmentally friendly while producing nutritious foods of high economical value. Thus, it is pertinent to improve the nutritive value of grasses and other forage plants in order to enhance animal production to obtain quality food. It is also vital to develop new forages which are efficiently utilised and wasted less by involving efficient animals. A combination of forage legumes, fresh or conserved grasses, crop residues and other feeds could help develop an animal production system which is economically efficient, beneficial and viable. Also, it is crucial to use efficient animals, improved forage conservation methods, better manure handling, and minimum

  20. Factors affecting forage stand establishment

    Directory of Open Access Journals (Sweden)

    Sulc R.M.

    1998-01-01

    Full Text Available Significant advances have been made in our knowledge of forage seed physiology, technology, and stand establishment practices; however, stand establishment continues to be one of the most common production problems affecting forage crops in the USA. There is a need for research on stand establishment of forage crops under abiotic and biotic stress. Although the forage seed industry produces and markets seed of high quality, new methods of assessing seed vigor are needed and their use should be expanded in the industry to enable matching seed lot performance to specific environmental conditions where performance can be maximized. Seed treatment and seed coating are used in the forage seed industry, and studies have shown they are of benefit in some environments. There is an increase in no-tillage seeding of forage crops, but improvements in the no-tillage planting equipment are needed to make them better suited to small seeds. Other recent developments in seeding techniques include broadcasting seed with dry granular and fluid fertilizers, which improves the efficiency of the seeding operation.

  1. Forage radish winter cover crop suppresses winter annual weeds in fall and before corn planting

    Science.gov (United States)

    Forage radish (Raphanus sativus L. var. longipinnatus) is a new winter cover crop in the Mid-Atlantic region. The objective of this project was to characterize the repeatability, amount, and duration of weed suppression during and after a fall-planted forage radish cover crop and to quantify the sub...

  2. Does greed help a forager survive?

    Science.gov (United States)

    Bhat, U.; Redner, S.; Bénichou, O.

    2017-06-01

    We investigate the role of greed on the lifetime of a random-walking forager on an initially resource-rich lattice. Whenever the forager lands on a food-containing site, all the food there is eaten and the forager can hop S more steps without food before starving. Upon reaching an empty site, the forager comes one time unit closer to starvation. The forager is also greedy—given a choice to move to an empty or to a food-containing site in its local neighborhood, the forager moves preferentially toward food. Surprisingly, the forager lifetime varies nonmonotonically with greed, with different senses of the nonmonotonicity in one and two dimensions. Also unexpectedly, the forager lifetime in one dimension has a huge peak for very negative greed where the forager is food averse.

  3. Shearwater foraging in the Southern Ocean: the roles of prey availability and winds.

    Directory of Open Access Journals (Sweden)

    Ben Raymond

    Full Text Available BACKGROUND: Sooty (Puffinus griseus and short-tailed (P. tenuirostris shearwaters are abundant seabirds that range widely across global oceans. Understanding the foraging ecology of these species in the Southern Ocean is important for monitoring and ecosystem conservation and management. METHODOLOGY/PRINCIPAL FINDINGS: Tracking data from sooty and short-tailed shearwaters from three regions of New Zealand and Australia were combined with at-sea observations of shearwaters in the Southern Ocean, physical oceanography, near-surface copepod distributions, pelagic trawl data, and synoptic near-surface winds. Shearwaters from all three regions foraged in the Polar Front zone, and showed particular overlap in the region around 140 degrees E. Short-tailed shearwaters from South Australia also foraged in Antarctic waters south of the Polar Front. The spatial distribution of shearwater foraging effort in the Polar Front zone was matched by patterns in large-scale upwelling, primary production, and abundances of copepods and myctophid fish. Oceanic winds were found to be broad determinants of foraging distribution, and of the flight paths taken by the birds on long foraging trips to Antarctic waters. CONCLUSIONS/SIGNIFICANCE: The shearwaters displayed foraging site fidelity and overlap of foraging habitat between species and populations that may enhance their utility as indicators of Southern Ocean ecosystems. The results highlight the importance of upwellings due to interactions of the Antarctic Circumpolar Current with large-scale bottom topography, and the corresponding localised increases in the productivity of the Polar Front ecosystem.

  4. Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals.

    Science.gov (United States)

    Peterson, Sarah H; Ackerman, Joshua T; Costa, Daniel P

    2015-07-07

    Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200-1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ(13)C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation.

  5. Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals

    Science.gov (United States)

    Peterson, Sarah H.; Ackerman, Joshua T.; Costa, Daniel P.

    2015-01-01

    Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200–1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ13C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation.

  6. Dynamic oceanography determines fine scale foraging behavior of Masked Boobies in the Gulf of Mexico.

    Science.gov (United States)

    Poli, Caroline L; Harrison, Autumn-Lynn; Vallarino, Adriana; Gerard, Patrick D; Jodice, Patrick G R

    2017-01-01

    During breeding, foraging marine birds are under biological, geographic, and temporal constraints. These contraints require foraging birds to efficiently process environmental cues derived from physical habitat features that occur at nested spatial scales. Mesoscale oceanography in particular may change rapidly within and between breeding seasons, and findings from well-studied systems that relate oceanography to seabird foraging may transfer poorly to regions with substantially different oceanographic conditions. Our objective was to examine foraging behavior of a pan-tropical seabird, the Masked Booby (Sula dactylatra), in the understudied Caribbean province, a moderately productive region driven by highly dynamic currents and fronts. We tracked 135 individuals with GPS units during May 2013, November 2013, and December 2014 at a regionally important breeding colony in the southern Gulf of Mexico. We measured foraging behavior using characteristics of foraging trips and used area restricted search as a proxy for foraging events. Among individual attributes, nest stage contributed to differences in foraging behavior whereas sex did not. Birds searched for prey at nested hierarchical scales ranging from 200 m-35 km. Large-scale coastal and shelf-slope fronts shifted position between sampling periods and overlapped geographically with overall foraging locations. At small scales (at the prey patch level), the specific relationship between environmental variables and foraging behavior was highly variable among individuals but general patterns emerged. Sea surface height anomaly and velocity of water were the strongest predictors of area restricted search behavior in random forest models, a finding that is consistent with the characterization of the Gulf of Mexico as an energetic system strongly influenced by currents and eddies. Our data may be combined with tracking efforts in the Caribbean province and across tropical regions to advance understanding of seabird

  7. Natal foraging philopatry in eastern Pacific hawksbill turtles.

    Science.gov (United States)

    Gaos, Alexander R; Lewison, Rebecca L; Jensen, Michael P; Liles, Michael J; Henriquez, Ana; Chavarria, Sofia; Pacheco, Carlos Mario; Valle, Melissa; Melero, David; Gadea, Velkiss; Altamirano, Eduardo; Torres, Perla; Vallejo, Felipe; Miranda, Cristina; LeMarie, Carolina; Lucero, Jesus; Oceguera, Karen; Chácon, Didiher; Fonseca, Luis; Abrego, Marino; Seminoff, Jeffrey A; Flores, Eric E; Llamas, Israel; Donadi, Rodrigo; Peña, Bernardo; Muñoz, Juan Pablo; Ruales, Daniela Alarcòn; Chaves, Jaime A; Otterstrom, Sarah; Zavala, Alan; Hart, Catherine E; Brittain, Rachel; Alfaro-Shigueto, Joanna; Mangel, Jeffrey; Yañez, Ingrid L; Dutton, Peter H

    2017-08-01

    The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

  8. Foraging task specialisation and foraging labour allocation in stingless bees

    NARCIS (Netherlands)

    Hofstede, Frouke Elisabeth

    2006-01-01

    Social bees collect nectar and pollen from flowering plants for energy of the adult bees and for feeding the larvae in the colony. The flowering patterns of plants imply that periods of high food availability are often followed by periods of meagre foraging conditions. Being dependent on such a dyna

  9. Execution Plans for Cyber Foraging

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø

    2008-01-01

    Cyber foraging helps small devices perform heavy tasks by opportunistically discovering and utilising available resources (such as computation, storage, bandwidth, etc.) held by larger, nearby peers. This offloading is done in an ad-hoc manner, as larger machines will not always be within reach. ...

  10. Latitudinal range influences the seasonal variation in the foraging behavior of marine top predators.

    Directory of Open Access Journals (Sweden)

    Stella Villegas-Amtmann

    Full Text Available Non-migratory resident species should be capable of modifying their foraging behavior to accommodate changes in prey abundance and availability associated with a changing environment. Populations that are better adapted to change will have higher foraging success and greater potential for survival in the face of climate change. We studied two species of resident central place foragers from temperate and equatorial regions with differing population trends and prey availability associated to season, the California sea lion (Zalophus californianus (CSL whose population is increasing and the endangered Galapagos sea lion (Zalophus wollebaeki (GSL whose population is declining. To determine their response to environmental change, we studied and compared their diving behavior using time-depth recorders and satellite location tags and their diet by measuring C and N isotope ratios during a warm and a cold season. Based on latitudinal differences in oceanographic productivity, we hypothesized that the seasonal variation in foraging behavior would differ for these two species. CSL exhibited greater seasonal variability in their foraging behavior as seen in changes to their diving behavior, foraging areas and diet between seasons. Conversely, GSL did not change their diving behavior between seasons, presenting three foraging strategies (shallow, deep and bottom divers during both. GSL exhibited greater dive and foraging effort than CSL. We suggest that during the warm and less productive season a greater range of foraging behaviors in CSL was associated with greater competition for prey, which relaxed during the cold season when resource availability was greater. GSL foraging specialization suggests that resources are limited throughout the year due to lower primary production and lower seasonal variation in productivity compared to CSL. These latitudinal differences influence their foraging success, pup survival and population growth reflected in

  11. Differential regulation of the foraging gene associated with task behaviors in harvester ants.

    Science.gov (United States)

    Ingram, Krista K; Kleeman, Lindsay; Peteru, Swetha

    2011-08-10

    The division of labor in social insect colonies involves transitions by workers from one task to another and is critical to the organization and ecological success of colonies. The differential regulation of genetic pathways is likely to be a key mechanism involved in plasticity of social insect task behavior. One of the few pathways implicated in social organization involves the cGMP-activated protein kinase gene, foraging, a gene associated with foraging behavior in social insect species. The association of the foraging gene with behavior is conserved across diverse species, but the observed expression patterns and proposed functions of this gene vary across taxa. We compared the protein sequence of foraging across social insects and explored whether the differential regulation of this gene is associated with task behaviors in the harvester ant, Pogonomyrmex occidentalis. Phylogenetic analysis of the coding region of the foraging gene reveals considerable conservation in protein sequence across insects, particularly among hymenopteran species. The absence of amino acid variation in key active and binding sites suggests that differences in behaviors associated with this gene among species may be the result of changes in gene expression rather than gene divergence. Using real time qPCR analyses with a harvester ant ortholog to foraging (Pofor), we found that the brains of harvester ant foragers have a daily fluctuation in expression of foraging with mRNA levels peaking at midday. In contrast, young workers inside the nest have low levels of Pofor mRNA with no evidence of daily fluctuations in expression. As a result, the association of foraging expression with task behavior within a species changes depending on the time of day the individuals are sampled. The amino acid protein sequence of foraging is highly conserved across social insects. Differences in foraging behaviors associated with this gene among social insect species are likely due to differences in gene

  12. Differential regulation of the foraging gene associated with task behaviors in harvester ants

    Directory of Open Access Journals (Sweden)

    Kleeman Lindsay

    2011-08-01

    Full Text Available Abstract Background The division of labor in social insect colonies involves transitions by workers from one task to another and is critical to the organization and ecological success of colonies. The differential regulation of genetic pathways is likely to be a key mechanism involved in plasticity of social insect task behavior. One of the few pathways implicated in social organization involves the cGMP-activated protein kinase gene, foraging, a gene associated with foraging behavior in social insect species. The association of the foraging gene with behavior is conserved across diverse species, but the observed expression patterns and proposed functions of this gene vary across taxa. We compared the protein sequence of foraging across social insects and explored whether the differential regulation of this gene is associated with task behaviors in the harvester ant, Pogonomyrmex occidentalis. Results Phylogenetic analysis of the coding region of the foraging gene reveals considerable conservation in protein sequence across insects, particularly among hymenopteran species. The absence of amino acid variation in key active and binding sites suggests that differences in behaviors associated with this gene among species may be the result of changes in gene expression rather than gene divergence. Using real time qPCR analyses with a harvester ant ortholog to foraging (Pofor, we found that the brains of harvester ant foragers have a daily fluctuation in expression of foraging with mRNA levels peaking at midday. In contrast, young workers inside the nest have low levels of Pofor mRNA with no evidence of daily fluctuations in expression. As a result, the association of foraging expression with task behavior within a species changes depending on the time of day the individuals are sampled. Conclusions The amino acid protein sequence of foraging is highly conserved across social insects. Differences in foraging behaviors associated with this gene among

  13. Corn in consortium with forages

    Directory of Open Access Journals (Sweden)

    Cássia Maria de Paula Garcia

    2013-12-01

    Full Text Available The basic premises for sustainable agricultural development with focus on rural producers are reducing the costs of production and aggregation of values through the use crop-livestock system (CLS throughout the year. The CLS is based on the consortium of grain crops, especially corn with tropical forages, mainly of the genus Panicum and Urochloa. The study aimed to evaluate the grain yield of irrigated corn crop intercropped with forage of the genus Panicum and Urochloa. The experiment was conducted at the Fazenda de Ensino, Pesquisa e Extensão – FEPE  of the Faculdade de Engenharia - UNESP, Ilha Solteira in an Oxisol in savannah conditions and in the autumn winter of 2009. The experimental area was irrigated by a center pivot and had a history of no-tillage system for 8 years. The corn hybrid used was simple DKB 390 YG at distances of 0.90 m. The seeds of grasses were sown in 0.34 m spacing in the amount of 5 kg ha-1, they were mixed with fertilizer minutes before sowing  and placed in a compartment fertilizer seeder and fertilizers were mechanically deposited in the soil at a depth of 0.03 m. The experimental design used was a randomized block with four replications and five treatments: Panicum maximum cv. Tanzania sown during the nitrogen fertilization (CTD of the corn; Panicum maximum cv. Mombaça sown during the nitrogen fertilization (CMD of the corn; Urochloa brizantha cv. Xaraés sown during the occasion of nitrogen fertilization (CBD of the corn; Urochloa ruziziensis cv. Comumsown during the nitrogen fertilization (CRD of the corn and single corn (control. The production components of corn: plant population per hectare (PlPo, number of ears per hectare (NE ha-1, number of rows per ear (NRE, number of kernels per row on the cob (NKR, number of grain in the ear (NGE and mass of 100 grains (M100G were not influenced by consortium with forage. Comparing grain yield (GY single corn and maize intercropped with forage of the genus Panicum

  14. Quality of the forage apparently consumed by beef calves in natural grassland under fertilization and oversown with cool season forage species

    Directory of Open Access Journals (Sweden)

    Denise Adelaide Gomes Elejalde

    2012-06-01

    Full Text Available The objective of this study was to evaluate the chemical composition of the forage apparently consumed by steers in a natural grassland on region of Campanha, in Rio Grande do Sul, Brazil, subjected or not to different inputs: NP - natural pasture without inputs; FNP - fertilized natural pasture and INP - improved natural grassland with fertilization and over-seeded with cultivated winter species. Three Angus steers testers and a variable number of regulator animals per experimental unit were utilized in order to maintain 13 kg of DM/100 kg of live weight (LW as forage allowance. One time at each season, hand plucking samples were performed along the daily grazing time simulating forage harvested by the animals. The collected samples after drying and grind were submitted to chemical analysis to determine the forage quality. Except in winter and spring, the values of neutral detergent fiber were higher than the critical value of 550 g/kg of DM, which could limit forage intake, demonstrating that the values of forage on offer provided (15.6; 13.7; 13.5; 15.8 kg of DM/100 kg of LW/day in summer, autumn, winter and spring, respectively were not restrictive to intake. The oversowing of winter cultivated species or fertilization positively alter the degradable fiber content. The seasons had marked influence on the chemical composition of forage apparently consumed; positively increasing some fractions of forage chemical composition in the seasons in which native or cultivated winter species increased their participation. The forage chemical composition is the determining factor in animal performance in natural pasture.

  15. Effect on Applying Organic Fertilizer on Cultivated Forage Yield in Alpine Region%高寒地区追施有机肥对栽培牧草产量的影响

    Institute of Scientific and Technical Information of China (English)

    李成泉

    2012-01-01

    通过在青海东部高寒高海拔地区旱作条件下对西北羊茅追施不同量有机肥的试验,研究结果表明牧草鲜草产量随有机肥的增施而逐渐提高,至1500kg.hm-2西北羊茅牧草产草量达最高,之后又随有机肥的增施而逐渐下降,且追施有机肥的各处理在中后期生长速度明显快于对照。%Festuca knyloviana topdressing different amounts of organic fertilizer in high altitude areas of the eastern Qinghai alpine , test results show that the forage fresh yield graduall izer adding to 1500kg · hm-2 forage production grass amounted to the highest, y increased with organic fertilafter gradually decreased with the increase of organic fertilizer applied, and chasing organic fertilizer processing significantly faster than the control in the late growth rate.

  16. Starvation dynamics of a greedy forager

    Science.gov (United States)

    Bhat, U.; Redner, S.; Bénichou, O.

    2017-07-01

    We investigate the dynamics of a greedy forager that moves by random walking in an environment where each site initially contains one unit of food. Upon encountering a food-containing site, the forager eats all the food there and can subsequently hop an additional S steps without food before starving to death. Upon encountering an empty site, the forager goes hungry and comes one time unit closer to starvation. We investigate the new feature of forager greed; if the forager has a choice between hopping to an empty site or to a food-containing site in its nearest neighborhood, it hops preferentially towards food. If the neighboring sites all contain food or are all empty, the forager hops equiprobably to one of these neighbors. Paradoxically, the lifetime of the forager can depend non-monotonically on greed, and the sense of the non-monotonicity is opposite in one and two dimensions. Even more unexpectedly, the forager lifetime in one dimension is substantially enhanced when the greed is negative; here the forager tends to avoid food in its local neighborhood. We also determine the average amount of food consumed at the instant when the forager starves. We present analytic, heuristic, and numerical results to elucidate these intriguing phenomena.

  17. Foraging currencies, metabolism and behavioural routines.

    Science.gov (United States)

    Houston, Alasdair I; McNamara, John M

    2014-01-01

    A fundamental issue in foraging theory is whether it is possible to find a simple currency that characterizes foraging behaviour. If such a currency exists, then it is tempting to argue that the selective forces that have shaped the evolution of foraging behaviour have been understood. We review previous work on currencies for the foraging behaviour of an animal that maximizes total energy gained. In many circumstances, it is optimal to maximize a suitably modified form of efficiency. We show how energy gain, predation and damage can be combined in a single currency based on reproductive value. We draw attention to the idea that hard work may have an adverse effect on an animal's condition. We develop a model of optimal foraging over a day when a forager's state consists of its energy reserves and its condition. Optimal foraging behaviour in our model depends on energy reserves, condition and time of day. The pattern of optimal behaviour depends strongly on assumptions about the probability that the forager is killed by a predator. If condition is important, no simple currency characterizes foraging behaviour, but behaviour can be understood in terms of the maximization of reproductive value. It may be optimal to adopt a foraging option that results in a rate of energy expenditure that is less than the rate associated with maximizing efficiency.

  18. Geographic profiling and animal foraging.

    Science.gov (United States)

    Le Comber, Steven C; Nicholls, Barry; Rossmo, D Kim; Racey, Paul A

    2006-05-21

    Geographic profiling was originally developed as a statistical tool for use in criminal cases, particularly those involving serial killers and rapists. It is designed to help police forces prioritize lists of suspects by using the location of crime scenes to identify the areas in which the criminal is most likely to live. Two important concepts are the buffer zone (criminals are less likely to commit crimes in the immediate vicinity of their home) and distance decay (criminals commit fewer crimes as the distance from their home increases). In this study, we show how the techniques of geographic profiling may be applied to animal data, using as an example foraging patterns in two sympatric colonies of pipistrelle bats, Pipistrellus pipistrellus and P. pygmaeus, in the northeast of Scotland. We show that if model variables are fitted to known roost locations, these variables may be used as numerical descriptors of foraging patterns. We go on to show that these variables can be used to differentiate patterns of foraging in these two species.

  19. Season and landscape composition affect pollen foraging distances and habitat use of honey bees.

    Science.gov (United States)

    Danner, Nadja; Molitor, Anna Maria; Schiele, Susanne; Härtel, Stephan; Steffan-Dewenter, Ingolf

    2016-09-01

    Honey bees (Apis mellifera L.) show a large variation in foraging distances and use a broad range of plant species as pollen resources, even in regions with intensive agriculture. However, it is unknown how increasing areas of mass-flowering crops like oilseed rape (Brassica napus; OSR) or a decrease of seminatural habitats (SNH) change the temporal and spatial availability of pollen resources for honey bee colonies, and thus foraging distances and frequency in different habitat types. We studied pollen foraging of honey bee colonies in 16 agricultural landscapes with independent gradients of OSR and SNH area within 2 km and used waggle dances and digital geographic maps with major land cover types to reveal the distance and visited habitat type on a landscape level. Mean pollen foraging distance of 1347 decoded bee dances was 1015 m (± 26 m; SEM). In spring, increasing area of flowering OSR within 2 km reduced mean pollen foraging distances from 1324 m to only 435 m. In summer, increasing cover of SNH areas close to the colonies (within 200 m radius) reduced mean pollen foraging distances from 846 to 469 m. Frequency of pollen foragers per habitat type, measured as the number of dances per hour and hectare, was equally high for SNH, grassland, and OSR fields, but lower for other crops and forests. In landscapes with a small proportion of SNH a significantly higher density of pollen foragers on SNH was observed, indicating that pollen resources in such simple agricultural landscapes are more limited. Overall, we conclude that SNH and mass-flowering crops can reduce foraging distances of honey bee colonies at different scales and seasons with possible benefits for the performance of honey bee colonies. Further, mixed agricultural landscapes with a high proportion of SNH reduce foraging densities of honey bees in SNH and thus possible competition for pollen resources.

  20. Human disturbance provides foraging opportunities for birds in primary subalpine forest

    DEFF Research Database (Denmark)

    DuBay, Shane G.; Hart Reeve, Andrew; Wu, Yongjie

    2017-01-01

    to species that naturally occur in edge, open, or disturbed habitats. With observations and experiments we provide evidence of insectivorous birds exploiting human disturbance in primary subalpine forest in the mountains of southern China, displaying behavioral flexibility to gain novel foraging...... or Cettia major, and Heteroxenicus stellatus. This behavior is likely a modification of pre-existing interspecific foraging associations with pheasants and large mammals in the region. These larger animals disturb the earth and lower vegetation layers upon passage and while foraging, exposing previously...

  1. Predicting foraging hotspots for Yelkouan Shearwater in the Black Sea

    Science.gov (United States)

    Pérez-Ortega, María; İsfendiyaroğlu, Süreyya

    2017-07-01

    The Yelkouan shearwater (Puffinus yelkouan) is a vulnerable species endemic to the Mediterranean Region, but there is little information of its ecology particularly when at sea. In this study, we assessed the habitat use by Yelkouan shearwater in the Black Sea during the breeding (March-July) and non-breeding (August-February) periods of 2013, using boat-based surveys and shore-based counts. We created a species distribution model (SDM) based on the environmental variables that most accurately reflected the oceanographic habitat of this species in order to delineate foraging hotspots. Our habitat modelling analyses suggest that Yelkouan shearwaters respond to complex bio-physical coupling, as evidenced by their association with oceanographic variables. Foraging Yelkouan shearwaters mainly occurred on the western Black Sea continental shelf, indicating that Yelkouan shearwaters were foraging in shallow, cold and coastal waters. In the non-breeding period, Yelkouan Shearwater occurred beyond the Black Sea continental shelf, a wide pelagic extension of sea, indicating that shearwaters foraged in deep, warm and pelagic waters. These results are consistent with earlier studies, which identified the Black Sea as an important congregation site for Mediterranean Yelkouan shearwater populations outside the breeding season. This study demonstrates how the integration of boat-based survey data, shore-based counts and modelling can provide a wider understanding of the linkage between marine ecosystems that is mediated by marine megafauna such as pelagic seabirds.

  2. Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

    Science.gov (United States)

    Woodin, M.C.; Michot, T.C.

    2006-01-01

    Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas and 51,650 activities from 57 redhead flocks in Louisiana. Males and females fed similarly, differing neither in levels of feeding (percent of all birds in flock that were feeding) (p>0.90) nor in percentages of birds feeding by diving, tipping, dipping, or gleaning from the surface (p>0.10). The foraging level of redheads in the upper Laguna Madre region was relatively constant throughout two winters. Foraging of redheads in early winter in Louisiana was significantly greater than redhead foraging in the upper Laguna Madre, but by late winter, foraging by redheads in Louisiana had declined to the same level as that shown by redheads foraging in the upper Laguna Madre. The overall foraging level of redheads from Chandeleur Sound was greater (41%) than that of redheads in the upper Laguna Madre (26%), yet it was quite similar to the 46% foraging level reported for redheads from the lower Laguna Madre. Redheads in the upper Laguna Madre region of Texas fed more by diving than did those in the Chandeleur Sound and the lower Laguna Madre. Diving increased in frequency in late winter. Greater reliance by redheads on diving in January and February indicates that the birds altered their foraging to feed in deeper water, suggesting that the large concentrations of redheads staging at this time for spring migration may have displaced some birds to alternative foraging sites. Our results imply that the most likely period for food resources to become limiting for wintering redheads is when they are staging in late winter. ?? Springer 2006.

  3. Developing Cyber Foraging Applications for Portable Devices

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø; Bouvin, Niels Olof

    2008-01-01

    This paper presents the Locusts cyber foraging framework. Cyber foraging is the opportunistic use of computing resources available in the nearby environment, and using such resources thus fall into the category of distributed computing. Furthermore, for the resources to be used efficiently......, parallel computing techniques must also be employed. Distributed and parallel computing are two concepts that are both notoriously known for being very hard for developers to grasp. Because of this one might think that techniques such as cyber foraging would have a hard time surviving outside of research...... environments. In this paper a framework is presented that has special focus on making cyber foraging accessible for all developers....

  4. Visual Foraging With Fingers and Eye Gaze.

    Science.gov (United States)

    Jóhannesson, Ómar I; Thornton, Ian M; Smith, Irene J; Chetverikov, Andrey; Kristjánsson, Árni

    2016-03-01

    A popular model of the function of selective visual attention involves search where a single target is to be found among distractors. For many scenarios, a more realistic model involves search for multiple targets of various types, since natural tasks typically do not involve a single target. Here we present results from a novel multiple-target foraging paradigm. We compare finger foraging where observers cancel a set of predesignated targets by tapping them, to gaze foraging where observers cancel items by fixating them for 100 ms. During finger foraging, for most observers, there was a large difference between foraging based on a single feature, where observers switch easily between target types, and foraging based on a conjunction of features where observers tended to stick to one target type. The pattern was notably different during gaze foraging where these condition differences were smaller. Two conclusions follow: (a) The fact that a sizeable number of observers (in particular during gaze foraging) had little trouble switching between different target types raises challenges for many prominent theoretical accounts of visual attention and working memory. (b) While caveats must be noted for the comparison of gaze and finger foraging, the results suggest that selection mechanisms for gaze and pointing have different operational constraints.

  5. U.S. Dairy Forage Research Center

    Data.gov (United States)

    Federal Laboratory Consortium — Vision: Leading the world in integrated dairy forage systems research. Mission: Providing dairy industry solutions for food security, environmental sustainability,...

  6. U.S. DAIRY FORAGE RESEARCH CENTER

    Data.gov (United States)

    Federal Laboratory Consortium — Vision: Leading the world in integrated dairy forage systems research. Mission: Providing dairy industry solutions for food security, environmental sustainability,...

  7. Evaluation of the nutritional value of locally produced forage in Korea using chemical analysis and ruminal fermentation

    Directory of Open Access Journals (Sweden)

    Kwang Seok Ki

    2017-03-01

    Full Text Available Objective The use of locally produced forage (LPF in cattle production has economic and environmental advantages over imported forage. The objective of this study was to characterize the nutritional value of LPF commonly used in Korea. Differences in ruminal fermentation characteristics were also examined for the LPF species commonly produced from two major production regions: Chungcheong and Jeolla. Methods Ten LPF (five from each of the two regions and six of the most widely used imported forages originating from North America were obtained at least three times throughout a year. Each forage species was pooled and analyzed for nutrient content using detailed chemical analysis. Ruminal fermentation characteristics were also determined by in vitro anaerobic incubations using strained rumen fluid for 0, 3, 6, 12, 24, and 48 h. At each incubation time, total gas, pH, ammonia, volatile fatty acid (VFA concentrations, and neutral detergent fiber digestibility were measured. By fitting an exponential model, gas production kinetics were obtained. Results Significant differences were found in the non-fiber carbohydrate (NFC content among the forage species and the regions (p<0.01. No nutrient, other than NFC, showed significant differences among the regions. Crude protein, NFC, and acid detergent lignin significantly differed by forage species. The amount of acid detergent insoluble protein tended to differ among the forages. The forages produced in Chungcheong had a higher amount of NFC than that in Jeolla (p<0.05. There were differences in ruminal fermentation of LPF between the two regions and interactions between regions and forage species were also significant (p<0.05. The pH following a 48-h ruminal fermentation was lower in the forages from Chungcheong than from Jeolla (p<0.01, and total VFA concentration was higher in Chungcheong than in Jeolla (p = 0.05. This implies that fermentation was more active with the forages from Chungcheong than from

  8. Potential of Caatinga forage plants in ruminant feeding

    OpenAIRE

    Mércia Virginia Ferreira dos Santos; Mário de Andrade Lira; José Carlos Batista Dubeux Junior; Adriana Guim; Alexandre Carneiro Leão de Mello; Márcio Vieira da Cunha

    2010-01-01

    Caatinga is the most important biome for the livestock in the Brazilian semi-arid region. This review paper aimed to present information on different forage aspects of caatinga vegetation for ruminant feeding. Caatinga vegetation is formed mainly by shrubs and small trees, usually presenting thorns, deciduous leaves, and leaf abscission occurring frequently at the onset of the dry season. Additional components of the botanical composition in this biome includes the families cactaceae, bromeli...

  9. Integrating multiple technologies to understand the foraging behaviour of Hawaiian monk seals

    Science.gov (United States)

    Littnan, Charles; Halpin, Patrick; Read, Andrew

    2017-01-01

    The objective of this research was to investigate and describe the foraging behaviour of monk seals in the main Hawaiian Islands. Specifically, our goal was to identify a metric to classify foraging behaviour from telemetry instruments. We deployed accelerometers, seal-mounted cameras and GPS tags on six monk seals during 2012–2014 on the islands of Molokai, Kauai and Oahu. We used pitch, calculated from the accelerometer, to identify search events and thus classify foraging dives. A search event and consequent ‘foraging dive’ occurred when the pitch was greater than or equal to 70° at a depth less than or equal to −3 m. By integrating data from the accelerometers with video and GPS, we were able to ground-truth this classification method and identify environmental variables associated with each foraging dive. We used Bayesian logistic regression to identify the variables that influenced search events. Dive depth, body motion (mean overall dynamic body acceleration during the dive) and proximity to the sea floor were the best predictors of search events for these seals. Search events typically occurred on long, deep dives, with more time spent at the bottom (more than 50% bottom time). We can now identify where monk seals are foraging in the main Hawaiian Islands (MHI) and what covariates influence foraging behaviour in this region. This increased understanding will inform management strategies and supplement outreach and recovery efforts. PMID:28405358

  10. Interactions between shoal size and conformity in guppy social foraging

    NARCIS (Netherlands)

    Day, R.L.; Macdonald, T.; Brown, C.; Laland, K.N.; Reader, S.M.

    2001-01-01

    Previous experimental studies have established that shoaling fish forage more effectively in large than small groups. We investigated how shoal size affects the foraging efficiency of laboratory populations of the guppy, Poecilia reticulata, exposed to different foraging tasks. Experiment 1

  11. Foraging behaviour of juvenile female New Zealand sea lions (Phocarctos hookeri in contrasting environments.

    Directory of Open Access Journals (Sweden)

    Elaine S Leung

    Full Text Available Foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. We investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female New Zealand (NZ sea lions (Phocarctos hookeri in two contrasting environments. The NZ sea lion is one of the rarest pinnipeds in the world. Most of the species is based at the subantarctic Auckland Islands (AI; considered to be marginal foraging habitat, with a recolonizing population on the Otago Peninsula, NZ mainland (considered to be more optimal habitat. We investigated how juvenile NZ sea lions adjust their foraging behaviour in contrasting environments by deploying satellite-linked platform transmitting terminals (PTTs and time-depth recorders (TDRs on 2-3 year-old females at AI (2007-2010 and Otago (2009-2010. Juvenile female NZ sea lions exhibited plasticity in body size and behaviour. Otago juveniles were significantly heavier than AI juveniles. Linear mixed effects models showed that study site had the most important effect on foraging behaviour, while mass and age had little influence. AI juveniles spent more time at sea, foraged over larger areas, and dove deeper and longer than Otago juveniles. It is difficult to attribute a specific cause to the observed contrasts in foraging behaviour because these differences may be driven by disparities in habitat/prey characteristics, conspecific density levels or interseasonal variation. Nevertheless, the smaller size and increased foraging effort of AI juveniles, combined with the lower productivity in this region, support the hypothesis that AI are less optimal habitat than Otago. It is more difficult for juveniles to forage in suboptimal habitats given their restricted foraging ability and lower tolerance for food limitation compared to adults. Thus, effective management measures should consider the impacts of low resource environments, along with changes that can

  12. Flexible foraging shapes the topology of plant-pollinator interaction networks.

    Science.gov (United States)

    Spiesman, Brian J; Gratton, Claudio

    2016-06-01

    In plant-pollinator networks, foraging choices by pollinators help form the connecting links between species. Flexible foraging should therefore play an important role in defining network topology. Factors such as morphological trait complementarity limit a pollinator's pool of potential floral resources, but which potential resource species are actually utilized at a location depends on local environmental and ecological context. Pollinators can be highly flexible foragers, but the effect of this flexibility on network topology remains unclear. To understand how flexible foraging affects network topology, we examined differences between sets of locally realized interactions and corresponding sets of potential interactions within 25 weighted plant-pollinator networks in two different regions of the United States. We examined two possible mechanisms for flexible foraging effects on realized networks: (1) preferential targeting of higher-density plant resources, which should increase network nestedness, and (2) context-dependent resource partitioning driven by interspecific competition, which should increase modularity and complementary specialization. We found that flexible foraging has strong effects on realized network topology. Realized connectance was much lower than connectance based on potential interactions, indicating a local narrowing of diet breadth. Moreover, the foraging choices pollinators made, which particular plant species to visit and at what rates, resulted in networks that were significantly less nested and significantly more modular and specialized than their corresponding networks of potential interactions. Preferentially foraging on locally abundant resources was not a strong driver of the realization of potential interactions. However, the degree of modularity and complementary specialization both increased with the number of competing pollinator species and with niche availability. We therefore conclude that flexible foraging affects realized

  13. Foraging behaviour by parasitoids in multiherbivore communities

    NARCIS (Netherlands)

    Rijk, de M.; Dicke, M.; Poelman, E.H.

    2013-01-01

    Parasitoid foraging decisions are often affected by community characteristics such as community diversity and complexity. As part of a complex habitat, the presence of unsuitable hosts may affect foraging behaviour of parasitoids. First, unsuitable herbivores may affect the localization of patches w

  14. Increased carrying capacity with perennial forage kochia

    Science.gov (United States)

    Carrying capacity can be increased on grass-dominated rangeland pastures by including perennial forage kochia (Kochia prostrata) as one of the plant components. The objectives of the study reported here were to compare the differences of traditional winter pastures versus pastures with forage kochi...

  15. Optimal forager against ideal free distributed prey.

    Science.gov (United States)

    Garay, József; Cressman, Ross; Xu, Fei; Varga, Zoltan; Cabello, Tomás

    2015-07-01

    The introduced dispersal-foraging game is a combination of prey habitat selection between two patch types and optimal-foraging approaches. Prey's patch preference and forager behavior determine the prey's survival rate. The forager's energy gain depends on local prey density in both types of exhaustible patches and on leaving time. We introduce two game-solution concepts. The static solution combines the ideal free distribution of the prey with optimal-foraging theory. The dynamical solution is given by a game dynamics describing the behavioral changes of prey and forager. We show (1) that each stable equilibrium dynamical solution is always a static solution, but not conversely; (2) that at an equilibrium dynamical solution, the forager can stabilize prey mixed patch use strategy in cases where ideal free distribution theory predicts that prey will use only one patch type; and (3) that when the equilibrium dynamical solution is unstable at fixed prey density, stable behavior cycles occur where neither forager nor prey keep a fixed behavior.

  16. Universality classes of foraging with resource renewal

    Science.gov (United States)

    Chupeau, M.; Bénichou, O.; Redner, S.

    2016-03-01

    We determine the impact of resource renewal on the lifetime of a forager that depletes its environment and starves if it wanders too long without eating. In the framework of a minimal starving random-walk model with resource renewal, there are three universal classes of behavior as a function of the renewal time. For sufficiently rapid renewal, foragers are immortal, while foragers have a finite lifetime otherwise. In the specific case of one dimension, there is a third regime, for sufficiently slow renewal, in which the lifetime of the forager is independent of the renewal time. We outline an enumeration method to determine the mean lifetime of the forager in the mortal regime.

  17. Foraging in groups affects giving-up densities: solo foragers quit sooner.

    Science.gov (United States)

    Carthey, Alexandra J R; Banks, Peter B

    2015-07-01

    The giving-up density framework is an elegant and widely adopted mathematical approach to measuring animals' foraging decisions at non-replenishing artificial resource patches. Under this framework, an animal should "give up" when the benefits of foraging are outweighed by the costs (e.g., predation risk, energetic, and/or missed opportunity costs). However, animals of many species may forage in groups, and group size is expected to alter perceived predation risk and hence influence quitting decisions. Yet, most giving-up density studies assume either that individuals forage alone or that giving-up densities are not affected by group foraging. For animals that forage both alone and in groups, differences in giving-up densities due to group foraging rather than experimental variables may substantially alter interpretation. However, no research to date has directly investigated how group foraging affects the giving-up density. We used remote-sensing cameras to identify instances of group foraging in two species of Rattus across three giving-up density experiments to determine whether group foraging influences giving-up densities. Both Rattus species have been observed to vary between foraging alone and in groups. In all three experiments, solo foragers left higher giving-up densities on average than did group foragers. This result has important implications for studies using giving-up densities to investigate perceived risk, the energetic costs of searching, handling time, digestion, and missed opportunity costs, particularly if groups of animals are more likely to experience certain experimental treatments. It is critically important that future giving-up density studies consider the effects of group foraging.

  18. Evaluation of the nutritional value of locally produced forage in Korea using chemical analysis and in vitro ruminal fermentation

    Science.gov (United States)

    Ki, Kwang Seok; Park, Su Bum; Lim, Dong Hyun; Seo, Seongwon

    2017-01-01

    Objective The use of locally produced forage (LPF) in cattle production has economic and environmental advantages over imported forage. The objective of this study was to characterize the nutritional value of LPF commonly used in Korea. Differences in ruminal fermentation characteristics were also examined for the LPF species commonly produced from two major production regions: Chungcheong and Jeolla. Methods Ten LPF (five from each of the two regions) and six of the most widely used imported forages originating from North America were obtained at least three times throughout a year. Each forage species was pooled and analyzed for nutrient content using detailed chemical analysis. Ruminal fermentation characteristics were also determined by in vitro anaerobic incubations using strained rumen fluid for 0, 3, 6, 12, 24, and 48 h. At each incubation time, total gas, pH, ammonia, volatile fatty acid (VFA) concentrations, and neutral detergent fiber digestibility were measured. By fitting an exponential model, gas production kinetics were obtained. Results Significant differences were found in the non-fiber carbohydrate (NFC) content among the forage species and the regions (pfermentation of LPF between the two regions and interactions between regions and forage species were also significant (pfermentation was lower in the forages from Chungcheong than from Jeolla (pfermentation was more active with the forages from Chungcheong than from Jeolla. Analysis of gas production profiles showed the rate of fermentation differed among forage species (pdigestion kinetics of LPF should be routinely employed to evaluate the correct nutritional value of LPF and to increase their use in the field. PMID:28002936

  19. Sexual segregation in foraging giraffe

    Science.gov (United States)

    Mramba, Rosemary Peter; Mahenya, Obeid; Siyaya, Annetjie; Mathisen, Karen Marie; Andreassen, Harry Peter; Skarpe, Christina

    2017-02-01

    Sexual segregation in giraffe is known to vary between savannas. In this study, we compared sexual segregation in giraffe in one nutrient-rich savanna, the Serengeti National Park, one nutrient-poor, Mikumi National Park, and one medium rich savanna, Arusha National Park, (from here on referred to just by name) based on effects of sexual size dimorphism and related hypotheses. Data were collected in the wet and dry seasons, by driving road transects and making visual observations of browsing giraffe. Additional data were collected from literature (plant chemistry; mammal communities). There was a noticeable difference in browsing by females and males and in browsing between the three savannas. Females browsed a higher diversity of tree species in Serengeti whereas males browsed a higher diversity in Arusha, while the diversity of species browsed in Mikumi was high and about the same in both sexes. Females selected for high concentrations of nitrogen and low concentrations of tannins and phenolics compared to males in Serengeti but selection in Mikumi was more complex. Males browsed higher in the canopy than females in all sites, but the browsing height was generally higher in Serengeti than Mikumi and Arusha. Season had an effect on the browsing height independent of sex in Mikumi, where giraffes browsed higher in the dry season compared to the wet season. Males spent more time browsing per tree compared to females in all three sites; however, browsing time in Mikumi was also affected by season, where giraffes had longer browsing bouts in the wet season compared to the dry season. We suggest that sexual differences in forage requirement and in foraging interacts with differences in tree chemistry and in competing herbivore communities between nutrient rich and nutrient poor savanna in shaping the sexual segregation.

  20. Sympatric cattle grazing and desert bighorn sheep foraging

    Science.gov (United States)

    Garrison, Kyle R.; Cain, James W.; Rominger, Eric M.; Goldstein, Elise J.

    2015-01-01

    Foraging behavior affects animal fitness and is largely dictated by the resources available to an animal. Understanding factors that affect forage resources is important for conservation and management of wildlife. Cattle sympatry is proposed to limit desert bighorn population performance, but few studies have quantified the effect of cattle foraging on bighorn forage resources or foraging behavior by desert bighorn. We estimated forage biomass for desert bighorn sheep in 2 mountain ranges: the cattle-grazed Caballo Mountains and the ungrazed San Andres Mountains, New Mexico. We recorded foraging bout efficiency of adult females by recording feeding time/step while foraging, and activity budgets of 3 age-sex classes (i.e., adult males, adult females, yearlings). We also estimated forage biomass at sites where bighorn were observed foraging. We expected lower forage biomass in the cattle-grazed Caballo range than in the ungrazed San Andres range and lower biomass at cattle-accessible versus inaccessible areas within the Caballo range. We predicted bighorn would be less efficient foragers in the Caballo range. Groundcover forage biomass was low in both ranges throughout the study (Jun 2012–Nov 2013). Browse biomass, however, was 4.7 times lower in the Caballo range versus the San Andres range. Bighorn in the Caballo range exhibited greater overall daily travel time, presumably to locate areas of higher forage abundance. By selecting areas with greater forage abundance, adult females in the Caballo range exhibited foraging bout efficiency similar to their San Andres counterparts but lower overall daily browsing time. We did not find a significant reduction in forage biomass at cattle-accessible areas in the Caballo range. Only the most rugged areas in the Caballo range had abundant forage, potentially a result of intensive historical livestock use in less rugged areas. Forage conditions in the Caballo range apparently force bighorn to increase foraging effort by

  1. Harvester ants use interactions to regulate forager activation and availability.

    Science.gov (United States)

    Pinter-Wollman, Noa; Bala, Ashwin; Merrell, Andrew; Queirolo, Jovel; Stumpe, Martin C; Holmes, Susan; Gordon, Deborah M

    2013-07-01

    Social groups balance flexibility and robustness in their collective response to environmental changes using feedback between behavioural processes that operate at different timescales. Here we examine how behavioural processes operating at two timescales regulate the foraging activity of colonies of the harvester ant, Pogonomyrmex barbatus, allowing them to balance their response to food availability and predation. Previous work showed that the rate at which foragers return to the nest with food influences the rate at which foragers leave the nest. To investigate how interactions inside the nest link the rates of returning and outgoing foragers, we observed outgoing foragers inside the nest in field colonies using a novel observation method. We found that the interaction rate experienced by outgoing foragers inside the nest corresponded to forager return rate, and that the interactions of outgoing foragers were spatially clustered. Activation of a forager occurred on the timescale of seconds: a forager left the nest 3-8 s after a substantial increase in interactions with returning foragers. The availability of outgoing foragers to become activated was adjusted on the timescale of minutes: when forager return was interrupted for more than 4-5 min, available foragers waiting near the nest entrance went deeper into the nest. Thus, forager activation and forager availability both increased with the rate at which foragers returned to the nest. This process was checked by negative feedback between forager activation and forager availability. Regulation of foraging activation on the timescale of seconds provides flexibility in response to fluctuations in food abundance, whereas regulation of forager availability on the timescale of minutes provides robustness in response to sustained disturbance such as predation.

  2. Optimal Foraging by Birds: Experiments for Secondary & Postsecondary Students

    Science.gov (United States)

    Pecor, Keith W.; Lake, Ellen C.; Wund, Matthew A.

    2015-01-01

    Optimal foraging theory attempts to explain the foraging patterns observed in animals, including their choice of particular food items and foraging locations. We describe three experiments designed to test hypotheses about food choice and foraging habitat preference using bird feeders. These experiments can be used alone or in combination and can…

  3. A review on studies in forage in China

    Institute of Scientific and Technical Information of China (English)

    LONG Wenxing; YANG Xiaobo; QI Meiying

    2007-01-01

    A review is made of the achievements in the collection,conservation,and genetic diversity of forage germplasm resources;methods and goals for forage breeding;and development and utilization of forage in China.The current problems based on the researches in forage are analyzed,and some suggestions are put forward.

  4. Experimental Wing Damage Affects Foraging Effort and Foraging Distance in Honeybees Apis mellifera

    Directory of Open Access Journals (Sweden)

    Andrew D. Higginson

    2011-01-01

    Full Text Available Bees acquire wing damage as they age, and loss of wing area affects longevity and behaviour. This may influence colony performance via effects on worker behaviour. The effects of experimental wing damage were studied in worker honeybees in observation hives by recording survivorship, how often and for how long bees foraged, and by decoding waggle dances. Mortality rate increased with both age and wing damage. Damaged bees carried out shorter and/or less frequent foraging trips, foraged closer to the hive, and reported the profitability of flower patches to be lower than did controls. These results suggest that wing damage caused a reduction in foraging ability, and that damaged bees adjusted their foraging behaviour accordingly. Furthermore, the results suggest that wing damage affects the profitability of nectar sources. These results have implications for the colony dynamics and foraging efficiency in honeybees.

  5. Space use and resource selection by foraging Indiana bats at the northern edge of their distribution

    Science.gov (United States)

    Jachowski, David S.; Johnson, Joshua B.; Dobony, Christopher A.; Edwards, John W.; Ford, W. Mark

    2014-01-01

    Despite 4 decades of conservation concern, managing endangered Indiana bat (Myotis sodalis) populations remains a difficult wildlife resource issue facing natural resource managers in the eastern United States. After small signs of population recovery, the recent emergence of white-nose syndrome has led to concerns of local and/or regional extirpation of the species. Where Indiana bats persist, retaining high-quality foraging areas will be critical to meet physiological needs and ensure successful recruitment and overwinter survival. However, insight into foraging behavior has been lacking in the Northeast of the USA. We radio-tracked 12 Indiana bats over 2 summers at Fort Drum, New York, to evaluate factors influencing Indiana bat resource selection during night-time foraging. We found that foraging space use decreased 2% for every 100 m increase in distance to water and 6% for every 100 m away from the forest edge. This suggests high use of riparian areas in close proximity to forest and is somewhat consistent with the species’ foraging ecology in the Midwest and upper South. Given the importance of providing access to high-quality foraging areas during the summer maternity season, Indiana bat conservation at the northern extent of the species’ range will be linked to retention of forested habitat in close proximity to riparian zones. 

  6. Migration, foraging, and residency patterns for Northern Gulf loggerheads: implications of local threats and international movements.

    Directory of Open Access Journals (Sweden)

    Kristen M Hart

    Full Text Available Northern Gulf of Mexico (NGoM loggerheads (Caretta caretta make up one of the smallest subpopulations of this threatened species and have declining nest numbers. We used satellite telemetry and a switching state-space model to identify distinct foraging areas used by 59 NGoM loggerheads tagged during 2010-2013. We tagged turtles after nesting at three sites, 1 in Alabama (Gulf Shores; n = 37 and 2 in Florida (St. Joseph Peninsula; n = 20 and Eglin Air Force Base; n = 2. Peak migration time was 22 July to 9 August during which >40% of turtles were in migration mode; the mean post-nesting migration period was 23.0 d (±13.8 d SD. After displacement from nesting beaches, 44 turtles traveled to foraging sites where they remained resident throughout tracking durations. Selected foraging locations were variable distances from tagging sites, and in 5 geographic regions; no turtles selected foraging sites outside the Gulf of Mexico (GoM. Foraging sites delineated using 50% kernel density estimation were located a mean distance of 47.6 km from land and in water with mean depth of -32.5 m; other foraging sites, delineated using minimum convex polygons, were located a mean distance of 43.0 km from land and in water with a mean depth of -24.9 m. Foraging sites overlapped with known trawling activities, oil and gas extraction activities, and the footprint of surface oiling during the 2010 Deepwater Horizon oil spill (n = 10. Our results highlight the year-round use of habitats in the GoM by loggerheads that nest in the NGoM. Our findings indicate that protection of females in this subpopulation requires both international collaborations and management of threats that spatially overlap with distinct foraging habitats.

  7. Migration, foraging, and residency patterns for Northern Gulf loggerheads: implications of local threats and international movements.

    Science.gov (United States)

    Hart, Kristen M; Lamont, Margaret M; Sartain, Autumn R; Fujisaki, Ikuko

    2014-01-01

    Northern Gulf of Mexico (NGoM) loggerheads (Caretta caretta) make up one of the smallest subpopulations of this threatened species and have declining nest numbers. We used satellite telemetry and a switching state-space model to identify distinct foraging areas used by 59 NGoM loggerheads tagged during 2010-2013. We tagged turtles after nesting at three sites, 1 in Alabama (Gulf Shores; n = 37) and 2 in Florida (St. Joseph Peninsula; n = 20 and Eglin Air Force Base; n = 2). Peak migration time was 22 July to 9 August during which >40% of turtles were in migration mode; the mean post-nesting migration period was 23.0 d (±13.8 d SD). After displacement from nesting beaches, 44 turtles traveled to foraging sites where they remained resident throughout tracking durations. Selected foraging locations were variable distances from tagging sites, and in 5 geographic regions; no turtles selected foraging sites outside the Gulf of Mexico (GoM). Foraging sites delineated using 50% kernel density estimation were located a mean distance of 47.6 km from land and in water with mean depth of -32.5 m; other foraging sites, delineated using minimum convex polygons, were located a mean distance of 43.0 km from land and in water with a mean depth of -24.9 m. Foraging sites overlapped with known trawling activities, oil and gas extraction activities, and the footprint of surface oiling during the 2010 Deepwater Horizon oil spill (n = 10). Our results highlight the year-round use of habitats in the GoM by loggerheads that nest in the NGoM. Our findings indicate that protection of females in this subpopulation requires both international collaborations and management of threats that spatially overlap with distinct foraging habitats.

  8. Worker honey bee pheromone regulation of foraging ontogeny

    Science.gov (United States)

    Pankiw, Tanya

    The evolution of sociality has configured communication chemicals, called primer pheromones, which play key roles in regulating the organization of social life. Primer pheromones exert relatively slow effects that fundamentally alter developmental, physiological, and neural systems. Here, I demonstrate how substances extracted from the surface of foraging and young pre-foraging worker bees regulated age at onset of foraging, a developmental process. Hexane-extractable compounds washed from foraging workers increased foraging age compared with controls, whereas extracts of young pre-foraging workers decreased foraging age. This represents the first known direct demonstration of primer pheromone activity derived from adult worker bees.

  9. Quitting time: When do honey bee foragers decide to stop foraging on natural resources?

    OpenAIRE

    Michael eRivera; Matina eDonaldson-Matasci; Anna eDornhaus

    2015-01-01

    Honey bee foragers may use both personal and social information when making decisions about when to visit resources. In particular, foragers may stop foraging at resources when their own experience indicates declining resource quality, or when social information, namely the delay to being able to unload nectar to receiver bees, indicates that the colony has little need for the particular resource being collected. Here we test the relative importance of these two factors in a natural setting, ...

  10. Espaçamento entre fileiras e densidade de semeadura do sorgo forrageiro para a região norte de Minas Gerais Row spacing and sowing density of forage sorghum in the northern region of Minas Gerais

    Directory of Open Access Journals (Sweden)

    Carlos Juliano Brant Albuquerque

    2011-06-01

    Full Text Available Em razão da sua resistência à seca, o sorgo forrageiro na forma de silagem é considerado um dos cultivos mais comuns para a alimentação de ruminantes em propriedades da região Norte de Minas Gerais. Para um melhor manejo cultural do sorgo, objetivou-se, neste trabalho, avaliar três densidades de plantas e três espaçamentos entre fileiras na condição climática do semiárido. Para isso, foram conduzidos experimentos, em dois anos agrícolas. Em cada ano foram instalados experimentos em áreas contíguas, utilizando se, respectivamente, os espaçamentos entre linhas de 50 cm, 70 cm e 90 cm. Cada experimento foi conduzido sob o delineamento experimental de blocos casualizados em esquema fatorial 4 x 3, com três repetições, sendo quatro cultivares e três densidades de semeadura. A viabilidade da redução do espaçamento entre fileiras no sorgo forrageiro é dependente da cultivar em função da condição climática. O aumento da densidade de semeadura proporciona redução na produtividade de matéria seca.Due to its resistance to drought, forage sorghum used as silage, is one of the most common feeds for ruminants on farms in the northern part of the State of Minas Gerais. The present research evaluated three planting densities and three forms of row spacing to determine their efficiency in the production of mass under the semiarid climatic conditions. Two experiments were conducted in two agricultural years. In each year, the experiments were conducted in contiguous areas using row spacing of 50, 70 and 90 cm and three different plant densities. Each experiment used a random blocks design in a 4 x 3 factorial scheme with three replicates, four cultivars and three sowing densities. The viability of reducing the space between rows was found to be dependent on the characteristics of each cultivar as well as the climatic conditions. Increasing sowing density resulted in a proportional reduction in the production of dry matter.

  11. Foraging strategies of the ant Ectatomma vizottoi (Hymenoptera, Formicidae)

    OpenAIRE

    Lima,Luan D.; Antonialli-Junior, William F.

    2013-01-01

    Foraging strategies of the ant Ectatomma vizottoi (Hymenoptera, Formicidae). Foraging activity may be limited by temperature, humidity, radiation, wind, and other abiotic factors, all of which can affect energy costs during foraging. Ectatomma vizottoi's biology has only recently been studied, and no detailed information is available on its foraging patterns or diet in the field. For this reason, and because foraging activity is an important part of the ecological success of social insects, t...

  12. Interactions Increase Forager Availability and Activity in Harvester Ants.

    Science.gov (United States)

    Pless, Evlyn; Queirolo, Jovel; Pinter-Wollman, Noa; Crow, Sam; Allen, Kelsey; Mathur, Maya B; Gordon, Deborah M

    2015-01-01

    Social insect colonies use interactions among workers to regulate collective behavior. Harvester ant foragers interact in a chamber just inside the nest entrance, here called the 'entrance chamber'. Previous studies of the activation of foragers in red harvester ants show that an outgoing forager inside the nest experiences an increase in brief antennal contacts before it leaves the nest to forage. Here we compare the interaction rate experienced by foragers that left the nest and ants that did not. We found that ants in the entrance chamber that leave the nest to forage experienced more interactions than ants that descend to the deeper nest without foraging. Additionally, we found that the availability of foragers in the entrance chamber is associated with the rate of forager return. An increase in the rate of forager return leads to an increase in the rate at which ants descend to the deeper nest, which then stimulates more ants to ascend into the entrance chamber. Thus a higher rate of forager return leads to more available foragers in the entrance chamber. The highest density of interactions occurs near the nest entrance and the entrances of the tunnels from the entrance chamber to the deeper nest. Local interactions with returning foragers regulate both the activation of waiting foragers and the number of foragers available to be activated.

  13. Interactions Increase Forager Availability and Activity in Harvester Ants.

    Directory of Open Access Journals (Sweden)

    Evlyn Pless

    Full Text Available Social insect colonies use interactions among workers to regulate collective behavior. Harvester ant foragers interact in a chamber just inside the nest entrance, here called the 'entrance chamber'. Previous studies of the activation of foragers in red harvester ants show that an outgoing forager inside the nest experiences an increase in brief antennal contacts before it leaves the nest to forage. Here we compare the interaction rate experienced by foragers that left the nest and ants that did not. We found that ants in the entrance chamber that leave the nest to forage experienced more interactions than ants that descend to the deeper nest without foraging. Additionally, we found that the availability of foragers in the entrance chamber is associated with the rate of forager return. An increase in the rate of forager return leads to an increase in the rate at which ants descend to the deeper nest, which then stimulates more ants to ascend into the entrance chamber. Thus a higher rate of forager return leads to more available foragers in the entrance chamber. The highest density of interactions occurs near the nest entrance and the entrances of the tunnels from the entrance chamber to the deeper nest. Local interactions with returning foragers regulate both the activation of waiting foragers and the number of foragers available to be activated.

  14. Fishing amplifies forage fish population collapses.

    Science.gov (United States)

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

  15. Quitting time: When do honey bee foragers decide to stop foraging on natural resources?

    Directory of Open Access Journals (Sweden)

    Michael eRivera

    2015-05-01

    Full Text Available Honey bee foragers may use both personal and social information when making decisions about when to visit resources. In particular, foragers may stop foraging at resources when their own experience indicates declining resource quality, or when social information, namely the delay to being able to unload nectar to receiver bees, indicates that the colony has little need for the particular resource being collected. Here we test the relative importance of these two factors in a natural setting, where colonies are using many dynamically changing resources. We recorded detailed foraging histories of individually marked bees, and identified when they appeared to abandon any resources (such as flower patches that they had previously been collecting from consistently. As in previous studies, we recorded duration of trophallaxis events (unloading nectar to receiver bees as a proxy for resource quality and the delays before returning foragers started trophallaxis as a proxy for social need for the resource. If these proxy measures accurately reflect changes in resource quality and social need, they should predict whether bees continue foraging or not. However, neither factor predicted when individuals stopped foraging on a particular resource, nor did they explain changes in colony-level foraging activity. This may indicate that other, as yet unstudied processes also affect individual decisions to abandon particular resources.

  16. Reindeer (Rangifer tarandus and climate change: Importance of winter forage

    Directory of Open Access Journals (Sweden)

    Thrine Moen Heggberget

    2002-06-01

    Full Text Available As a consequence of increasing greenhouse gas concentrations, climate change is predicted to be particularly pronounced, although regionally variable, in the vast arctic, sub-arctic and alpine tundra areas of the northern hemisphere. Here, we review winter foraging conditions for reindeer and caribou (Rangifer tarandus living in these areas, and consider diet, forage quality and distribution, accessibility due to snow variation, and effects of snow condition on reindeer and caribou populations. Finally, we hypothesise how global warming may affect wild mountain reindeer herds in South Norway. Energy-rich lichens often dominate reindeer and caribou diets. The animals also prefer lichens, and their productivity has been shown to be higher on lichen-rich than on lichen-poor ranges. Nevertheless, this energy source appears to be neither sufficient as winter diet for reindeer or caribou (at least for pregnant females nor necessary. Some reindeer and caribou populations seem to be better adapted to a non-lichen winter diet, e.g. by a larger alimentary tract. Shrubs appear to be the most common alternative winter forage, while some grasses appear to represent a good, nutritionally-balanced winter diet. Reindeer/caribou make good use of a wide variety of plants in winter, including dead and dry parts that are digested more than expected based on their fibre content. The diversity of winter forage is probably important for the mineral content of the diet. A lichen-dominated winter diet may be deficient in essential dietary elements, e.g. minerals. Sodium in particular may be marginal in inland winter ranges. Our review indicates that most Rangifer populations with lichen-dominated winter diets are either periodically or continuously heavily harvested by humans or predators. However, when population size is mainly limited by food, accessible lichen resources are often depleted. Plant studies simulating climatic change indicate that a warmer, wetter

  17. Flooding tolerance of forage legumes.

    Science.gov (United States)

    Striker, Gustavo G; Colmer, Timothy D

    2016-06-20

    We review waterlogging and submergence tolerances of forage (pasture) legumes. Growth reductions from waterlogging in perennial species ranged from >50% for Medicago sativa and Trifolium pratense to Lotus corniculatus, L. tenuis, and T. fragiferum For annual species, waterlogging reduced Medicago truncatula by ~50%, whereas Melilotus siculus and T. michelianum were not reduced. Tolerant species have higher root porosity (gas-filled volume in tissues) owing to aerenchyma formation. Plant dry mass (waterlogged relative to control) had a positive (hyperbolic) relationship to root porosity across eight species. Metabolism in hypoxic roots was influenced by internal aeration. Sugars accumulate in M. sativa due to growth inhibition from limited respiration and low energy in roots of low porosity (i.e. 4.5%). In contrast, L. corniculatus, with higher root porosity (i.e. 17.2%) and O2 supply allowing respiration, maintained growth better and sugars did not accumulate. Tolerant legumes form nodules, and internal O2 diffusion along roots can sustain metabolism, including N2 fixation, in submerged nodules. Shoot physiology depends on species tolerance. In M. sativa, photosynthesis soon declines and in the longer term (>10 d) leaves suffer chlorophyll degradation, damage, and N, P, and K deficiencies. In tolerant L corniculatus and L. tenuis, photosynthesis is maintained longer, shoot N is less affected, and shoot P can even increase during waterlogging. Species also differ in tolerance of partial and complete shoot submergence. Gaps in knowledge include anoxia tolerance of roots, N2 fixation during field waterlogging, and identification of traits conferring the ability to recover after water subsides.

  18. Characterization of winter foraging locations of Adélie penguins along the Western Antarctic Peninsula, 2001-2002

    Science.gov (United States)

    Erdmann, Eric S.; Ribic, Christine A.; Patterson-Fraser, Donna L.; Fraser, William R.

    2011-07-01

    In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin ( Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (penguin's foraging, the analysis of sea ice data of a higher resolution than was available for this study may help elucidate the role of sea ice in affecting Adélie penguin winter foraging behavior within the pack ice.

  19. Characterization of winter foraging locations of Adélie penguins along the Western Antarctic Peninsula, 2001–2002

    Science.gov (United States)

    Erdmann, Eric S.; Ribic, Christine; Patterson-Fraser, Donna L.; Fraser, William R.

    2011-01-01

    In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin (Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (penguin's foraging, the analysis of sea ice data of a higher resolution than was available for this study may help elucidate the role of sea ice in affecting Adélie penguin winter foraging behavior within the pack ice.

  20. Forage fish of the Pacific Rim as revealed by diet of a piscivorous seabird: Synchrony and relationships with sea surface temperature

    Science.gov (United States)

    Thayer, J.A.; Bertram, D.F.; Hatch, Shyla A.; Hipfner, M.J.; Slater, L.; Sydeman, W.J.; Watanuki, Y.

    2008-01-01

    We tested the hypothesis of synchronous interannual changes in forage fish dynamics around the North Pacific Rim. To do this, we sampled forage fish communities using a seabird predator, the rhinoceros auklet (Cerorhinca monocerata), at six coastal study sites from Japan to California. We investigated whether take of forage fishes was related to local marine conditions as indexed by sea surface temperature (SST). SST was concordant across sites in the eastern Pacific, but inversely correlated between east and west. Forage fish communities consisted of anchovy (Engraulis spp.), sandlance (Ammodytes spp.), capelin (Mallotus spp.), and juvenile rockfish (Sebastes spp.), among others, and take of forage fish varied in response to interannual and possibly lower-frequency oceanographic variability. Take of primary forage species were significantly related to changes in SST only at the eastern sites. We found synchrony in interannual variation of primary forage fishes across several regions in the eastern Pacific, but no significant east-west correlations. Specifically in the Japan Sea, factors other than local SST or interannual variability may more strongly influence forage fishes. Predator diet sampling offers a fishery-independent, large-scale perspective on forage fish dynamics that may be difficult to obtain using conventional means of study. ?? 2008 NRC.

  1. Fast carnivores and slow herbivores: differential foraging strategies among grizzly bears in the Canadian Arctic.

    Science.gov (United States)

    Edwards, Mark A; Derocher, Andrew E; Hobson, Keith A; Branigan, Marsha; Nagy, John A

    2011-04-01

    Categorizing animal populations by diet can mask important intrapopulation variation, which is crucial to understanding a species' trophic niche width. To test hypotheses related to intrapopulation variation in foraging or the presence of diet specialization, we conducted stable isotope analysis (δ(13)C, δ(15)N) on hair and claw samples from 51 grizzly bears (Ursus arctos) collected from 2003 to 2006 in the Mackenzie Delta region of the Canadian Arctic. We examined within-population differences in the foraging patterns of males and females and the relationship between trophic position (derived from δ(15)N measurements) and individual movement. The range of δ(15)N values in hair and claw (2.0-11.0‰) suggested a wide niche width and cluster analyses indicated the presence of three foraging groups within the population, ranging from near-complete herbivory to near-complete carnivory. We found no linear relationship between home range size and trophic position when the data were continuous or when grouped by foraging behavior. However, the movement rate of females increased linearly with trophic position. We used multisource dual-isotope mixing models to determine the relative contributions of seven prey sources within each foraging group for both males and females. The mean bear dietary endpoint across all foraging groups for each sex fell toward the center of the mixing polygon, which suggested relatively well-mixed diets. The primary dietary difference across foraging groups was the proportional contribution of herbaceous foods, which decreased for both males and females from 42-76 to 0-27% and 62-81 to 0-44%, respectively. Grizzlies of the Mackenzie Delta live in extremely harsh conditions and identifying within-population diet specialization has improved our understanding of varying habitat requirements within the population.

  2. Evolution of foraging behavior in Drosophilid larvae

    Science.gov (United States)

    Rivera-Alba, Marta; Kabra, Mayank; Branson, Kristin; Mirth, Christen

    2015-03-01

    Drosophilids, like other insects, go through a larval phase before metamorphosing into adults. Larvae increase their body weight by several orders of magnitude in a few days. We therefore hypothesized that foraging behavior is under strong evolutionary pressure to best fit the larval environment. To test our hypothesis we used a multidisciplinary approach to analyze foraging behavior across species and larval stages. First, we recorded several videos of larvae foraging for each of 47 Drosophilid species. Then, using a supervised machine learning approach, we automatically annotated the video collection for the foraging sub-behaviors, including crawling, turning, head casting or burrowing. We also computed over 100 features to describe the posture and dynamics of each animal in each video frame. From these data, we fit models to the behavior of each species. The models each had the same parametric form, but differed in the exact parameters. By simulating larva behavior in virtual arenas we can infer which properties of the environments are better for each species. Comparisons between these inferred environments and the actual environments where these animals live will give us a deeper understanding about the evolution of foraging behavior in Drosophilid larvae.

  3. Avaliação dos atributos físicos do solo em consórcio de forrageiras e milho em sucessão com soja em região de cerrados Evaluation of soil physical properties in a forage-corn intercropping in succession with soybean in the cerrado region

    Directory of Open Access Journals (Sweden)

    Veridiana Zocoler de Mendonça

    2013-02-01

    V4 and corn without intercropping (control, in the experimental area of UNESP, campus Ilha Solteira. Summer soybean was sown on the crop remains of previous treatments. To determine macro and microporosity, total porosity and bulk density soil was sampled twice, after the maize and after the soybean harvest. From the results, it was concluded that in Cerrado region, the crop succession improved soil macroporosity, total porosity and bulk density, regardless of the use of forages intercropped with maize.

  4. Alfalfa interseeded into silage corn can serve as a cover crop and subsequent forage crop

    Science.gov (United States)

    Alfalfa (Medicago sativa) and corn (Zea mays) silage are commonly grown in rotation in dairy forage production systems throughout the northern regions of the USA. Alfalfa interseeded into silage corn could potentially serve two purposes: as a cover crop during the silage corn production year, and as...

  5. Use and breeding of forage grasses in the North Central USA

    Science.gov (United States)

    Forage grasses are used for conservation harvesting, usually hay or balage, and for grazing within the North Central region of the USA. Historically, smooth bromegrass, timothy, reed canarygrass, and orchardgrass have been important species and they still exist in many old hay fields. Tall fescue, m...

  6. Fourteen years of forage monitoring on the California Central Coast shows tremendous variation

    Science.gov (United States)

    Royce Larsen; Karl Striby; Marc Horney

    2015-01-01

    To better understand forage production (above ground biomass) and precipitation patterns in the Central Coast region of California, the first in a growing network of primary production monitoring sites were established in 2001. The California Central Coast has a Mediterranean climate with cool, moist winters and hot, dry summers, and is dominated by annual grasslands...

  7. The mechanism for weed suppression by a forage radish cover crop

    Science.gov (United States)

    In the Mid-Atlantic region, forage radish (Raphanus sativus L. var. longipinnatus) winter cover crops planted prior to 1 September suppress winter annual weeds from fall until early April. Little is known about the mechanism of this weed suppression. Published research reports suggest that allelopat...

  8. Spatiotemporal chemotactic model for ant foraging

    Science.gov (United States)

    Ramakrishnan, Subramanian; Laurent, Thomas; Kumar, Manish; Bertozzi, Andrea L.

    2014-12-01

    In this paper, we present a generic theoretical chemotactic model that accounts for certain emergent behaviors observed in ant foraging. The model does not have many of the constraints and limitations of existing models for ants colony dynamics and takes into account the distinctly different behaviors exhibited in nature by ant foragers in search of food and food ferrying ants. Numerical simulations based on the model show trail formation in foraging ant colonies to be an emergent phenomenon and, in particular, replicate behavior observed in experiments involving the species P. megacephala. The results have broader implications for the study of randomness in chemotactic models. Potential applications include the developments of novel algorithms for stochastic search in engineered complex systems such as robotic swarms.

  9. Seasonal Changes in Forage Nutrients and Mineral Contents in Water Resources,Forage and Yak Blood

    Institute of Scientific and Technical Information of China (English)

    阎萍

    2005-01-01

    This paper reports results of a study conducted to investigate the concentrations of seven mineral elements in yak blood, forage and water resources around the Qinghai Lake in Qinghai Province in different seasons. Meanwhile, the nutritional compositions of the forage were also surveyed. The results suggest that the mineral elements and the forage nutrients change in a seasonal pattern. In yak blood,the sodium(Na)concentration varies from 0.291 to 0.034 mg/mL,and this is lower than the normal value. In the forage,the ratio calcium(Ca)to phosphorus(P)is 4.06~7.47:1 and potassium(K)to Na 30~27:1. These results indicate that the nutrition of the yak in the area is deficient in Na but high in K. For the withered forage sampled in February,the protein content is only 31.14% of the total protein in the forage growing at puerile stage in June. The severe loss of protein by 68. 9% and decrease of effective nutrients in the wintered forage are considered to be the reasons resulting in the poor condition of yak in winter and spring seasons.

  10. Ungulate exclusion, conifer thinning and mule deer forage in northeastern New Mexico

    Science.gov (United States)

    Kramer, David W.; Sorensen, Grant E.; Taylor, Chase A.; Cox, Robert D.; Gipson, Philip S.; Cain, James W.

    2015-01-01

    The southwestern United States has experienced expansion of conifer species (Juniperus spp. and Pinus ponderosa) into areas of semi-arid grassland over the past century. The expansion of conifers can limit palatable forage and reduce grass and forb communities. Conifer species are sometimes thinned through hydraulic mulching or selective cutting. We assessed the effects of these treatments on mule deer (Odocoileus hemionus) habitat in northeastern New Mexico to determine if conifer thinning improved cover of preferred forage species for mule deer in areas with and without ungulates. We measured plant cover and occurrence of preferred forage species in the summers of 2011 and 2012. An ongoing regional drought probably reduced vegetation response, with preferred forage species and herbaceous cover responding to conifer thinning or ungulate exclusion immediately following treatment, but not the following year. In 2011, areas that received thinning treatments had a higher abundance of preferred forage when compared to sites with no treatment. Grass coverage exhibited an immediate response in 2011, with ungulate exclosures containing 8% more coverage than areas without exclosures. The results suggest that conifer thinning and ungulate exclusion may elicit a positive response, however in the presence of drought; the positive effects are only short-term.

  11. Novel foraging in the swash zone on Pacific sand crabs (Emerita analoga, Hippidae) by mallards

    Science.gov (United States)

    Lafferty, Kevin D.; McLaughlin, John P.; Dugan, Jenifer E.

    2013-01-01

    Mallards (Anas platyrhynchos) have been observed foraging on intertidal Pacific sand crabs (Hippidae, Emerita analoga) in the swash zone of sandy beaches around Coal Oil Point Reserve, California, and several other beaches on the west coast since at least November 2010. Unlike foraging shorebirds, Mallards do not avoid incoming swashes. Instead, the incoming swash lifts and deposits them down the beach. Shorebirds and diving ducks commonly feed on sand crabs, but sand crabs appear to be a novel behavior and food source for Mallards. Previous surveys of beaches did not report foraging Mallards on regional beaches, whereas foraging Mallards were common in contemporary (recent) surveys and anecdotal reports. Observations of this potentially new behavior were separated by as much as 1,300 km, indicating that this was not a local phenomenon. Mallards foraged singly, in pairs, and in flocks. An expansion of diet to sand crabs carries risks of exposure to surf, human disturbance, high salt intake, and transmission of acanthocephalan and trematode parasites for Mallards but has the benefit of providing a dependable source of animal protein.

  12. Nectar profitability, not empty honey stores, stimulate recruitment and foraging in Melipona scutellaris (Apidae, Meliponini).

    Science.gov (United States)

    Schorkopf, Dirk Louis P; de Sá Filho, Geovan Figueirêdo; Maia-Silva, Camila; Schorkopf, Martina; Hrncir, Michael; Barth, Friedrich G

    2016-10-01

    In stingless bees (Meliponini) like in many other eusocial insect colonies food hoarding plays an important role in colony survival. However, very little is known on how Meliponini, a taxon restricted to tropical and subtropical regions, respond to different store conditions. We studied the impact of honey removal on nectar foraging activity and recruitment behaviour in Melipona scutellaris and compared our results with studies of the honey bee Apis mellifera. As expected, foraging activity increased significantly during abundance of artificial nectar and when increasing its profitability. Foraging activity on colony level could thereby frequently increase by an order of magnitude. Intriguingly, however, poor honey store conditions did not induce increased nectar foraging or recruitment activity. We discuss possible reasons explaining why increasing recruitment and foraging activity are not used by meliponines to compensate for poor food conditions in the nest. Among these are meliponine specific adaptations to climatic and environmental conditions, as well as physiology and brood rearing, such as mass provisioning of the brood.

  13. Dynamic foraging of a top predator in a seasonal polar marine environment.

    Science.gov (United States)

    Weinstein, Ben G; Friedlaender, Ari S

    2017-09-15

    The seasonal movement of animals at broad spatial scales provides insight into life-history, ecology and conservation. By combining high-resolution satellite-tagged data with hierarchical Bayesian movement models, we can associate spatial patterns of movement with marine animal behavior. We used a multi-state mixture model to describe humpback whale traveling and area-restricted search states as they forage along the West Antarctic Peninsula. We estimated the change in the geography, composition and characteristics of these behavioral states through time. We show that whales later in the austral fall spent more time in movements associated with foraging, traveled at lower speeds between foraging areas, and shifted their distribution northward and inshore. Seasonal changes in movement are likely due to a combination of sea ice advance and regional shifts in the primary prey source. Our study is a step towards dynamic movement models in the marine environment at broad scales.

  14. Article original Agronomy Foraging behaviour of Apis mellifera ...

    African Journals Online (AJOL)

    Hilaire

    Foraging behaviour of Apis mellifera adansonii and its impact on pollination, fruit and .... temperature is about 25°C. ... area before November 15, sugar baby variety of ... abundance, direct observations of the foraging ..... 4 Cane J.H., 2002.

  15. A properly adjusted forage harvester can save time and money

    Science.gov (United States)

    A properly adjusted forage harvester can save fuel and increase the realizable milk per ton of your silage. This article details the adjustments necessary to minimize energy while maximizing productivity and forage quality....

  16. Foraging Behavior of Odontomachus bauri on Barro Colorado Island, Panama

    Directory of Open Access Journals (Sweden)

    Birgit Ehmer

    1995-01-01

    Full Text Available Foraging behavior and partitioning of foraging areas of Odonomachus bauri were investigated on Barro Colorado Island in Panama. The activity of the ants did not show any daily pattern; foragers were active day and night. The type of prey captured by O. bauri supports the idea that in higher Odontomachus and Anochetus species, the high speed of mandible closure serves more for generating power than capturing elusive prey. Polydomous nests may enable O. bauri colonies to enlarge their foraging areas.

  17. Stable Isotopes Reveal Long-Term Fidelity to Foraging Grounds in the Galapagos Sea Lion (Zalophus wollebaeki)

    Science.gov (United States)

    Drago, Massimiliano; Franco-Trecu, Valentina; Cardona, Luis; Inchausti, Pablo; Tapia, Washington; Páez-Rosas, Diego

    2016-01-01

    Most otariids have colony-specific foraging areas during the breeding season, when they behave as central place foragers. However, they may disperse over broad areas after the breeding season and individuals from different colonies may share foraging grounds at that time. Here, stable isotope ratios in the skull bone of adult Galapagos sea lions (Zalophus wollebaeki) were used to assess the long-term fidelity of both sexes to foraging grounds across the different regions of the Galapagos archipelago. Results indicated that the stable isotope ratios (δ13C and δ15N) of sea lion bone significantly differed among regions of the archipelago, without any significant difference between sexes and with a non significant interaction between sex and region. Moreover, standard ellipses, estimated by Bayesian inference and used as a measure of the isotopic resource use area at the population level, overlapped widely for the sea lions from the southern and central regions, whereas the overlap of the ellipses for sea lions from the central and western regions was small and non-existing for those from the western and southern regions. These results suggest that males and females from the same region within the archipelago use similar foraging grounds and have similar diets. Furthermore, they indicate that the exchange of adults between regions is limited, thus revealing a certain degree of foraging philopatry at a regional scale within the archipelago. The constraints imposed on males by an expanded reproductive season (~ 6 months), resulting from the weak reproductive synchrony among females, and those imposed on females by a very long lactation period (at least one year but up to three years), may explain the limited mobility of adult Galapagos sea lions of both sexes across the archipelago. PMID:26808381

  18. Determination of region-specific data of yield and quality of alternatives to silage maize in fodder crops – field trails with forage gras and clover grass mixtures, Sorghum as well as whole plant silage of grain

    Directory of Open Access Journals (Sweden)

    Wosnitza, Andrea

    2014-02-01

    Full Text Available This project should generate current regional results over a period of three years about the parameter yield and quality of alternative fodder crops to maize; this includes grass and clover grass mixtures, silage maize, varieties of Sorghum/millets and whole plant silages of wheat, rye and triticale. The tested silage maize showed the highest and most reliable average dry matter yield with 23 tons per hectare, with a very low variance. The Sorghum and millet varieties had dry matter yields of 3 to 5 tons per hectare below the silage maize yield but with individual values fluctuating in a broad range within years and locations. With values far below 28% the dry matter contents were not suitable for ensiling. The grass and clover grass mixtures are good, stable and established alternatives to maize for silage. They achieved high yields comparable with these of Sorghum but stable and with a highly suitable dry matter content for ensiling. The yield of the whole plant silages was up to 22% lower compared with maize. So none of the alternative crops can compete with the high level yield of silage maize in its favoured region, therefore would be a combination of two crops recommended. But some individual locally adapted mixtures or varieties of the alternative crops reached nearly 80% of the maize yield. Silage maize showed the highest level of the net energy content for lactation (NEL, followed by the values of the fodder crops and the whole plant silages. The Sorghum varieties showed the lowest NEL value of all tested cultures. The highest crude protein showed the fodder crops contents. Silage maize, Sorghum and the whole plant silages had values lying nearly around the 50% mark of the fodder crops.

  19. Flight dynamics of Cory's shearwater foraging in a coastal environment.

    Science.gov (United States)

    Paiva, Vitor H; Guilford, Tim; Meade, Jessica; Geraldes, Pedro; Ramos, Jaime A; Garthe, Stefan

    2010-01-01

    Flight dynamics theories are influenced by two major topics: how birds adapt their flight to cope with heterogeneous habitats, and whether birds plan to use the wind field or simply experience it. The aim of this study was to understand the flight dynamics of free-flying Cory's shearwaters in relation to the wind characteristics on the coastal upwelling region of continental Portugal. We deployed recently miniaturised devices-global positioning system loggers to collect precise and detailed information on birds' positions and motions. Prevalent winds were blowing from the north-east and adults used those winds by adjusting their flight directions mainly towards north-west and south-west, flying with cross and tail winds, respectively, and avoiding head winds. This is confirmation that Cory's shearwaters use a shear soaring flying strategy while exploiting the environment for food: adults foraged mainly with cross winds and their ground speed was not constant during all foraging trips as it changed dynamically as a result of the ocean surface shear winds. During travelling phases, ground speed was strongly influenced by the position of the bird with regard to the wind direction, as ground speed increased significantly with increasing tail wind component (TWC) values. Adults appear to choose foraging directions to exploit ambient wind, in order to improve shear soaring efficiency (cross winding) and exploit diurnal changes in tail wind strength to maximise commuting efficiency. We report, for the first time, precise ground speed values (GPS-derived data) and computed actual flight speed values (using TWC analysis) for Cory's shearwater.

  20. Nitrogen transfer between herbivores and their forage species

    NARCIS (Netherlands)

    Sjogersten, Sofie; Kuijper, Dries P. J.; van der Wal, Rene; Loonen, Maarten J. J. E.; Huiskes, Ad H. L.; Woodin, Sarah J.

    2010-01-01

    Herbivores may increase the productivity of forage plants; however, this depends on the return of nutrients from faeces to the forage plants. The aim of this study was to test if nitrogen (N) from faeces is available to forage plants and whether the return of nutrients differs between plant species

  1. Blue Oak Canopy Effect on Seasonal Forage Production and Quality

    Science.gov (United States)

    William E. Frost; Neil K. McDougald; Montague W. Demment

    1991-01-01

    Forage production and forage quality were measured seasonally beneath the canopy of blue oak (Quercus douglasii) and in open grassland at the San Joaquin Experimental Range. At the March and peak standing crop sampling dates forage production was significantly greater (p=.05) beneath blue oak compared to open grassland. At most sampling dates, the...

  2. Scheduling and development support in the Scavenger cyber foraging system

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø; Bouvin, Niels Olof

    2010-01-01

    Cyber foraging is a pervasive computing technique where small mobile devices offload resource intensive tasks to stronger computing machinery in the vicinity. One of the main challenges within cyber foraging is that it is very difficult to develop cyber foraging enabled applications. An applicati...

  3. Nocturnal Foraging by Red-Legged Kittiwakes, a Surface Feeding Seabird That Relies on Deep Water Prey During Reproduction.

    Science.gov (United States)

    Kokubun, Nobuo; Yamamoto, Takashi; Kikuchi, Dale M; Kitaysky, Alexander; Takahashi, Akinori

    2015-01-01

    Narrow foraging specialization may increase the vulnerability of marine predators to climate change. The red-legged kittiwake (Rissa brevirostris) is endemic to the Bering Sea and has experienced drastic population fluctuations in recent decades, presumably due to climate-driven changes in food resources. Red-legged kittiwakes are presumed to be a nocturnal surface-foraging seabird that feed almost entirely on deep water Myctophidae fishes. However, there is little empirical evidence confirming their nocturnal foraging activity during the breeding season. This study investigated the foraging behavior of red-legged kittiwakes by combining GPS tracking, accelerometry, and dietary analyses at the world's largest breeding colony of red-legged kittiwakes on St. George I. GPS tracking of 5 individuals revealed that 82.5% of non-flight behavior (including foraging and resting) occurred over the ocean basin (bottom depth >1,000 m). Acceleration data from 4 birds showed three types of behaviors during foraging trips: (1) flight, characterized by regular wing flapping, (2) resting on water, characterized by non-active behavior, and (3) foraging, when wing flapping was irregular. The proportions of both foraging and resting behaviors were higher at night (14.1 ± 7.1% and 20.8 ± 14.3%) compared to those during the day (6.5 ± 3.0% and 1.7 ± 2.7%). The mean duration of foraging (2.4 ± 2.9 min) was shorter than that of flight between prey patches (24.2 ± 53.1 min). Dietary analyses confirmed myctophids as the dominant prey (100% by occurrence and 98.4 ± 2.4% by wet-weight). Although the sample size was limited, these results suggest that breeding red-legged kittiwakes concentrated their foraging on myctophids available at the surface during nighttime in deep water regions. We propose that the diel patterns and ephemeral nature of their foraging activity reflected the availability of myctophids. Such foraging specialization may exacerbate the vulnerability of red

  4. Cell Wall Diversity in Forage Maize

    NARCIS (Netherlands)

    Torres, A.F.; Noordam-Boot, C.M.M.; Dolstra, Oene; Weijde, van der Tim; Combes, Eliette; Dufour, Philippe; Vlaswinkel, Louis; Visser, R.G.F.; Trindade, L.M.

    2015-01-01

    Genetic studies are ideal platforms for assessing the extent of genetic diversity, inferring the genetic architecture, and evaluating complex trait interrelations for cell wall compositional and bioconversion traits relevant to bioenergy applications. Through the characterization of a forage maiz

  5. Investigating Optimal Foraging Theory in the Laboratory

    Science.gov (United States)

    Harden, Siegfried; Grilliot, Matthew E.

    2014-01-01

    Optimal foraging theory is a principle that is often presented in the community ecology section of biology textbooks, but also can be demonstrated in the laboratory. We introduce a lab activity that uses an interactive strategy to teach high school and/or college students about this ecological concept. The activity is ideal because it engages…

  6. The Dynamics of Infant Visual Foraging

    Science.gov (United States)

    Robertson, Steven S.; Guckenheimer, John; Masnick, Amy M.; Bacher, Leigh F.

    2004-01-01

    Human infants actively forage for visual information from the moment of birth onward. Although we know a great deal about how stimulus characteristics influence looking behavior in the first few postnatal weeks, we know much less about the intrinsic dynamics of the behavior. Here we show that a simple stochastic dynamical system acts…

  7. Balancing organization and flexibility in foraging dynamics.

    Science.gov (United States)

    Tabone, Michaelangelo; Ermentrout, Bard; Doiron, Brent

    2010-10-07

    Proper pattern organization and reorganization are central problems facing many biological networks which thrive in fluctuating environments. However, in many cases the mechanisms that organize system activity oppose those that support behavioral flexibility. Thus, a balance between pattern organization and pattern flexibility is critically important for overall biological fitness. We study this balance in the foraging strategies of ant colonies exploiting food in dynamic environments. We present discrete time and space simulations of colony activity that uses a pheromone-based recruitment strategy biasing foraging towards a food source. After food relocation, the pheromone must evaporate sufficiently before foraging can shift colony attention to a new food source. The amount of food consumed within the dynamic environment depends non-monotonically on the pheromone evaporation time constant-with maximal consumption occurring at a time constant which balances trail formation and trail flexibility. A deterministic, 'mean field' model of pheromone and foragers on trails mimics our colony simulations. This reduced framework captures the essence of the flexibility-organization balance, and relates optimal pheromone evaporation to the timescale of the dynamic environment. We expect that the principles exposed in our study will generalize and motivate novel analysis across a broad range systems biology.

  8. Responses of late-lactation cows to forage substitutes in low-forage diets supplemented with by-products

    Science.gov (United States)

    In response to drought-induced shortages of forage and increased corn and soy prices, a study was conducted to evaluate lactation response of dairy cows to lower-forage diets supplemented with forage substitutes and with byproduct feeds entirely substituted for corn grain and soybean feeds. The desi...

  9. From foraging to autonoetic consciousness: The primal self as a consequence of embodied prospective foraging

    Institute of Scientific and Technical Information of China (English)

    Thomas T.HILLS; Stephen BUTTERFILL

    2015-01-01

    The capacity to adapt to resource distributions by modulating the frequency of exploratory and exploitative behaviors is common across metazoans and is arguably a principal selective force in the evolution of cognition.Here we (1) review recent work investigating behavioral and biological commonalities between external foraging in space and internal foraging over environmcnts specified by cognitive representations,and (2) explore the implications of these commonalities for understanding the origins of the self.Behavioural commonalities include the capacity for what is known as area-restricted search in the ecological literature:this is search focussed around locations where resources have been found in the past,but moving away from locations where few resources are found,and capable of producing movement patterns mimicking Lévy flights.Area-restricted search shares a neural basis across metazoans,and these biological commonalities in vertebrates suggest an evolutionary homology between external and internal foraging.Internal foraging,and in particular a form we call embodied prospective foraging,makes available additional capacities for prediction based on search through a cognitive representation of the external environment,and allows predictions about outcomes of possible future actions.We demonstrate that cognitive systems that use embodied prospective foraging require a primitive sense of self,needed to distinguish actual from simulated action.This relationship has implications for understanding the evolution of autonoetic consciousness and self-awareness [Current Zoology 61 (2):368-381,2015].

  10. Perching but not foraging networks predict the spread of novel foraging skills in starlings.

    Science.gov (United States)

    Boogert, Neeltje J; Nightingale, Glenna F; Hoppitt, William; Laland, Kevin N

    2014-11-01

    The directed social learning hypothesis suggests that information does not spread evenly through animal groups, but rather individual characteristics and patterns of physical proximity guide the social transmission of information along specific pathways. Network-based diffusion analysis (NBDA) allows researchers to test whether information spreads following a social network. However, the explanatory power of different social networks has rarely been compared, and current models do not easily accommodate random effects (e.g. allowing for individuals within groups to correlate in their asocial solving rates). We tested whether the spread of two novel foraging skills through captive starling groups was affected by individual- and group-level random and fixed effects (i.e. sex, age, body condition, dominance rank and demonstrator status) and perching or foraging networks. We extended NBDA to include random effects and conducted model discrimination in a Bayesian context. We found that social learning increased the rate at which birds acquired the novel foraging task solutions by 6.67 times, and acquiring one of the two novel foraging task solutions facilitated the asocial acquisition of the other. Surprisingly, the spread of task solutions followed the perching rather than the foraging social network. Upon acquiring a task solution, foraging performance was facilitated by the presence of group mates. Our results highlight the importance of considering more than one social network when predicting the spread of information through animal groups. This article is part of a Special Issue entitled: Cognition in the wild.

  11. Conservation and Ecology of Marine Forage Fishes--Proceedings of a Research Symposium, September 2012

    Science.gov (United States)

    Liedtke, Theresa; Gibson, Caroline; Lowry, Dayv; Fagergren, Duane

    2013-01-01

    Locally and globally, there is growing recognition of the critical roles that herring, smelt, sand lance, eulachon, and other forage fishes play in marine ecosystems. Scientific and resource management entities throughout the Salish Sea, agree that extensive information gaps exist, both in basic biological knowledge and parameters critical to fishery management. Communication and collaboration among researchers also is inadequate. Building on the interest and enthusiasm generated by recent forage fish workshops and symposia around the region, the 2012 Research Symposium on the Conservation and Ecology of Marine Forage Fishes was designed to elucidate practical recommendations for science and policy needs and actions, and spur further collaboration in support for the precautionary management of forage fish. This dynamic and productive event was a joint venture of the Northwest Straits Commission Forage Fish Program, U.S. Geological Survey (USGS), Washington Department of Fish and Wildlife (WDFW), and The Puget Sound Partnership. The symposium was held on September 12–14, 2012, at the University of Washington, Friday Harbor Laboratories campus. Sixty scientists, graduate students, and fisheries policy experts convened; showcasing ongoing research, conservation, and management efforts targeting forage fish from regional and national perspectives. The primary objectives of this event were to: (1) review current research and management related to marine forage fish species; and (2) identify priority science and policy needs and actions for Washington, British Columbia, and the entire West Coast. Given the diversity of knowledge, interests, and disciplines surrounding forage fish on both sides of the international border, the organizing committee made a concerted effort to contact many additional experts who, although unable to attend, provided valuable insights and ideas to the symposium structure and discussions. The value of the symposium format was highlighted in

  12. Intra-seasonal variation in foraging behavior among Adélie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

    Science.gov (United States)

    Lyver, P.O.B.; MacLeod, C.J.; Ballard, G.; Karl, B.J.; Barton, K.J.; Adams, J.; Ainley, D.G.; Wilson, P.R.

    2011-01-01

    We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins, Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.

  13. Foraging strategies of the ant Ectatomma vizottoi (Hymenoptera, Formicidae

    Directory of Open Access Journals (Sweden)

    Luan D. Lima

    2013-12-01

    Full Text Available Foraging strategies of the ant Ectatomma vizottoi (Hymenoptera, Formicidae. Foraging activity may be limited by temperature, humidity, radiation, wind, and other abiotic factors, all of which can affect energy costs during foraging. Ectatomma vizottoi's biology has only recently been studied, and no detailed information is available on its foraging patterns or diet in the field. For this reason, and because foraging activity is an important part of the ecological success of social insects, the present study aimed to investigate E. vizottoi's foraging strategies and dietary habits. First, we determined how abiotic factors constrained E. vizottoi's foraging patterns in the field by monitoring the foraging activity of 16 colonies on eight different days across two seasons. Second, we characterized E. vizottoi's diet by monitoring another set of 26 colonies during peak foraging activity. Our results show that E. vizottoi has foraging strategies that are similar to those of congeneric species. In spite of having a low efficiency index, colonies adopted strategies that allowed them to successfully obtain food resources while avoiding adverse conditions. These strategies included preying on other ant species, a foraging tactic that could arise if a wide variety of food items are not available in the environment or if E. vizottoi simply prefers, regardless of resource availability, to prey on other invertebrates and especially on other ant species.

  14. Phototaxic foraging of the archaepaddler, a hypothetical deep-sea species.

    Science.gov (United States)

    Bertin, R J; van de Grind, W A

    1998-01-01

    An autonomous agent (animat, hypothetical animal), called the (archae) paddler, is simulated in sufficient detail to regard its simulated aquatic locomotion (paddling) as physically possible. The paddler is supposed to be a model of an animal that might exist, although it is perfectly possible to view it as a model of a robot that might be built. The agent is assumed to navigate in a simulated deep-sea environment, where it forages for autoluminescent prey. It uses a biologically inspired phototaxic foraging strategy, while paddling in a layer just above the bottom. The advantage of this living space is that the navigation problem--and hence our model--is essentially two-dimensional. Moreover, the deep-sea environment is physically simple (and hence easy to simulate): no significant currents, constant temperature, completely dark. A foraging performance metric is developed that circumvents the necessity to solve the traveling salesman problem. A parametric simulation study then quantifies the influence of habitat factors, such as the density of prey, and body geometry (e.g., placement, direction and directional selectivity of the eyes) on foraging success. Adequate performance proves to require a specific body geometry adapted to the habitat characteristics. In general, performance degrades gracefully for modest changes of the geometric and habitat parameters, indicating that we work in a stable region of "design space." The parameters have to strike a compromise between, on the one hand, to "see" as many targets at the same time as possible. One important conclusion is that simple reflex-based navigation can be surprisingly efficient. Additionally, performance in a global task (foraging) depends strongly on local parameters such as visual direction tuning, position of the eyes and paddles, and so forth. Behavior and habitat "mold" the body, and the body geometry strongly influences performance. The resulting platform enables further testing of foraging strategies

  15. Foraging behavior links climate variability and reproduction in North Pacific albatrosses.

    Science.gov (United States)

    Thorne, Lesley H; Hazen, Elliott L; Bograd, Steven J; Foley, David G; Conners, Melinda G; Kappes, Michelle A; Kim, Hyemi M; Costa, Daniel P; Tremblay, Yann; Shaffer, Scott A

    2015-01-01

    Climate-driven environmental change in the North Pacific has been well documented, with marked effects on the habitat and foraging behavior of marine predators. However, the mechanistic linkages connecting climate-driven changes in behavior to predator populations are not well understood. We evaluated the effects of climate-driven environmental variability on the reproductive success and foraging behavior of Laysan and Black-footed albatrosses breeding in the Northwest Hawaiian Islands during both brooding and incubating periods. We assessed foraging trip metrics and reproductive success using data collected from 2002-2012 and 1981-2012, respectively, relative to variability in the location of the Transition Zone Chlorophyll Front (TZCF, an important foraging region for albatrosses), sea surface temperature (SST), Multivariate ENSO Index (MEI), and the North Pacific Gyre Oscillation index (NPGO). Foraging behavior for both species was influenced by climatic and oceanographic factors. While brooding chicks, both species traveled farther during La Niña conditions, when NPGO was high and when the TZCF was farther north (farther from the breeding site). Models showed that reproductive success for both species showed similar trends, correlating negatively with conditions observed during La Niña events (low MEI, high SST, high NPGO, increased distance to TZCF), but models for Laysan albatrosses explained a higher proportion of the variation. Spatial correlations of Laysan albatross reproductive success and SST anomalies highlighted strong negative correlations (>95 %) between habitat use and SST. Higher trip distance and/or duration during brooding were associated with decreased reproductive success. Our findings suggest that during adverse conditions (La Niña conditions, high NPGO, northward displacement of the TZCF), both Laysan and Black-footed albatrosses took longer foraging trips and/or traveled farther during brooding, likely resulting in a lower reproductive

  16. Scavenger: Transparent Development of Efficient Cyber Foraging Applications

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø

    2010-01-01

    Cyber foraging is a pervasive computing technique where small mobile devices offload resource intensive tasks to stronger computing machinery in the vicinity. This paper presents Scavenger-a new cyber foraging system supporting easy development of mobile cyber foraging applications, while still...... delivering efficient, mobile use of remote computing resources through the use of a custom built mobile code execution environment and a new dual-profiling scheduler. One of the main difficulties within cyber foraging is that it is very challenging for application programmers to develop cyber foraging...... enabled applications. An application using cyber foraging is working with mobile, distributed and, possibly, parallel computing; fields within computer science known to be hard for programmers to grasp. In this paper it is shown by example, how a highly distributed, parallel, cyber foraging enabled...

  17. Summertime blues: August foraging leaves honey bees empty-handed.

    Science.gov (United States)

    Couvillon, Margaret J; Fensome, Katherine A; Quah, Shaun Kl; Schürch, Roger

    2014-01-01

    A successful honey bee forager tells her nestmates the location of good nectar and pollen with the waggle dance, a symbolic language that communicates a distance and direction. Because bees are adept at scouting out profitable forage and are very sensitive to energetic reward, we can use the distance that bees communicate via waggle dances as a proxy for forage availability, where the further the bees fly, the less forage can be found locally. Previously we demonstrated that bees fly furthest in the summer compared with spring or autumn to bring back forage that is not necessarily of better quality. Here we show that August is also the month when significantly more foragers return with empty crops (P = 7.63e-06). This provides additional support that summer may represent a seasonal foraging challenge for honey bees.

  18. The regulation of ant colony foraging activity without spatial information.

    Science.gov (United States)

    Prabhakar, Balaji; Dektar, Katherine N; Gordon, Deborah M

    2012-01-01

    Many dynamical networks, such as the ones that produce the collective behavior of social insects, operate without any central control, instead arising from local interactions among individuals. A well-studied example is the formation of recruitment trails in ant colonies, but many ant species do not use pheromone trails. We present a model of the regulation of foraging by harvester ant (Pogonomyrmex barbatus) colonies. This species forages for scattered seeds that one ant can retrieve on its own, so there is no need for spatial information such as pheromone trails that lead ants to specific locations. Previous work shows that colony foraging activity, the rate at which ants go out to search individually for seeds, is regulated in response to current food availability throughout the colony's foraging area. Ants use the rate of brief antennal contacts inside the nest between foragers returning with food and outgoing foragers available to leave the nest on the next foraging trip. Here we present a feedback-based algorithm that captures the main features of data from field experiments in which the rate of returning foragers was manipulated. The algorithm draws on our finding that the distribution of intervals between successive ants returning to the nest is a Poisson process. We fitted the parameter that estimates the effect of each returning forager on the rate at which outgoing foragers leave the nest. We found that correlations between observed rates of returning foragers and simulated rates of outgoing foragers, using our model, were similar to those in the data. Our simple stochastic model shows how the regulation of ant colony foraging can operate without spatial information, describing a process at the level of individual ants that predicts the overall foraging activity of the colony.

  19. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater.

    Science.gov (United States)

    Berlincourt, Maud; Angel, Lauren P; Arnould, John P Y

    2015-01-01

    Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1-70.0%) of time at sea resting on water and 18.2% (range: 2.3-49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8-237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.

  20. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater.

    Directory of Open Access Journals (Sweden)

    Maud Berlincourt

    Full Text Available Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals, is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1 resting on water, (2 flapping flight, (3 gliding flight, (4 foraging (i.e., surface foraging and diving events, and (5 taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1-70.0% of time at sea resting on water and 18.2% (range: 2.3-49.6% foraging. Individuals made 76.4 ± 65.3 dives (range: 8-237 per foraging trip (mean duration 9.0 ± 1.9 s, with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.

  1. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater

    Science.gov (United States)

    Berlincourt, Maud; Angel, Lauren P.; Arnould, John P. Y.

    2015-01-01

    Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1–70.0%) of time at sea resting on water and 18.2% (range: 2.3–49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8–237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey. PMID:26439491

  2. Análisis de las concentraciones de azufre en agua, alimento y gas sulfúrico ruminal de rebaños bovinos de carne de las regiones de La Araucanía, Los Ríos y Los Lagos de Chile Determination of sulphur contents in water, forage and ruminal hydrogen sulphide concentrations in beef cattle herds from La Araucanía, Los Ríos y Los Lagos regions of Chile

    Directory of Open Access Journals (Sweden)

    M Gómez

    2011-01-01

    íodos fue Sulphur is an essential element for the metabolism of ruminant animals. However, high dietary concentrations of sulphur are potentially harmful. The purpose of this study was to measure the forage and water sulphur content in samples from 45 beef herds from the La Araucanía, Los Ríos y Los Lagos regions of Chile. Additionally, ruminal gas hydrogen sulphide (H2S concentrations were obtained from 5 animals on each farm. Samples were collected during the spring 2008 and summer 2009. Pasture sulphur content was 1,482 ± 592 ppm in the spring and 1,471 ± 448 ppm in the summer. Water sulphur concentrations in all farms was < 1.5 ppm each season. Ruminal gas H2S concentrations in animals was 273 ± 187.5 ppm and 245.4 ± 173 ppm in spring and summer, respectively. Positive and significant correlations were found between pasture sulphur content and ruminal H2S concentration for both periods. Estimated total sulphur intake considering pastures and water was < 0.2% sulfur on a dry matter basis. The results of this study suggest that forage and water sulphur concentrations in Southern Chile do not represent a potential risk of intoxication in grazing beef cattle.

  3. The application of foraging theory to the information searching behaviour of general practitioners.

    Science.gov (United States)

    Dwairy, Mai; Dowell, Anthony C; Stahl, Jean-Claude

    2011-08-23

    General Practitioners (GPs) employ strategies to identify and retrieve medical evidence for clinical decision making which take workload and time constraints into account. Optimal Foraging Theory (OFT) initially developed to study animal foraging for food is used to explore the information searching behaviour of General Practitioners. This study is the first to apply foraging theory within this context.Study objectives were: 1. To identify the sequence and steps deployed in identifiying and retrieving evidence for clinical decision making. 2. To utilise Optimal Foraging Theory to assess the effectiveness and efficiency of General Practitioner information searching. GPs from the Wellington region of New Zealand were asked to document in a pre-formatted logbook the steps and outcomes of an information search linked to their clinical decision making, and fill in a questionnaire about their personal, practice and information-searching backgrounds. A total of 115/155 eligible GPs returned a background questionnaire, and 71 completed their information search logbook. GPs spent an average of 17.7 minutes addressing their search for clinical information. Their preferred information sources were discussions with colleagues (38% of sources) and books (22%). These were the two most profitable information foraging sources (15.9 min and 9.5 min search time per answer, compared to 34.3 minutes in databases). GPs nearly always accessed another source when unsuccessful (95% after 1st source), and frequently when successful (43% after 2nd source). Use of multiple sources accounted for 41% of searches, and increased search success from 70% to 89%. By consulting in foraging terms the most 'profitable' sources of information (colleagues, books), rapidly switching sources when unsuccessful, and frequently double checking, GPs achieve an efficient trade-off between maximizing search success and information reliability, and minimizing searching time. As predicted by foraging theory, GPs

  4. The application of foraging theory to the information searching behaviour of general practitioners

    Directory of Open Access Journals (Sweden)

    Dowell Anthony C

    2011-08-01

    Full Text Available Abstract Background General Practitioners (GPs employ strategies to identify and retrieve medical evidence for clinical decision making which take workload and time constraints into account. Optimal Foraging Theory (OFT initially developed to study animal foraging for food is used to explore the information searching behaviour of General Practitioners. This study is the first to apply foraging theory within this context. Study objectives were: 1. To identify the sequence and steps deployed in identifiying and retrieving evidence for clinical decision making. 2. To utilise Optimal Foraging Theory to assess the effectiveness and efficiency of General Practitioner information searching. Methods GPs from the Wellington region of New Zealand were asked to document in a pre-formatted logbook the steps and outcomes of an information search linked to their clinical decision making, and fill in a questionnaire about their personal, practice and information-searching backgrounds. Results A total of 115/155 eligible GPs returned a background questionnaire, and 71 completed their information search logbook. GPs spent an average of 17.7 minutes addressing their search for clinical information. Their preferred information sources were discussions with colleagues (38% of sources and books (22%. These were the two most profitable information foraging sources (15.9 min and 9.5 min search time per answer, compared to 34.3 minutes in databases. GPs nearly always accessed another source when unsuccessful (95% after 1st source, and frequently when successful (43% after 2nd source. Use of multiple sources accounted for 41% of searches, and increased search success from 70% to 89%. Conclusions By consulting in foraging terms the most 'profitable' sources of information (colleagues, books, rapidly switching sources when unsuccessful, and frequently double checking, GPs achieve an efficient trade-off between maximizing search success and information reliability, and

  5. 长白山地区5种可利用饲草营养成分及单宁含量动态分析%The dynamic analysis of nutrient and tannin content of five kinds of available forage in Changbai Mountain region

    Institute of Scientific and Technical Information of China (English)

    马敏; 赵微; 李成云

    2015-01-01

    of the contents of total polyphenols, simple polyphenols, tannins, and condensed tannins that changed in an irregular wave type but were on a downward trend. The results demonstrates that the plant specie is the main factor influencing the plant phenolic content. Through the determination of nutrient content and RFV, it can be drawn that all the five kinds of plants have considerable feeding value. In addition, the dynamically analyzing of tannin content provides data sup-porting for the rational using of these five kinds of forage, takes full advantage of the vegetable tannin's functions such as protecting rumen bypass pro-tein and preventing bloat and taps out the appli-cation potential of the five kinds of common for-age in ChangBai Mountain region further.

  6. Optimal Foraging of Renewable Resources

    CERN Document Server

    Enright, John J

    2011-01-01

    Consider a team of agents in the plane searching for and visiting target points that appear in a bounded environment according to a stochastic renewal process with a known absolutely continuous spatial distribution. Agents must detect targets with limited-range onboard sensors. It is desired to minimize the expected waiting time between the appearance of a target point, and the instant it is visited. When the sensing radius is small, the system time is dominated by time spent searching, and it is shown that the optimal policy requires the agents to search a region at a relative frequency proportional to the square root of its renewal rate. On the other hand, when targets appear frequently, the system time is dominated by time spent servicing known targets, and it is shown that the optimal policy requires the agents to service a region at a relative frequency proportional to the cube root of its renewal rate. Furthermore, the presented algorithms in this case recover the optimal performance achieved by agents ...

  7. Uncovering the complexity of ant foraging trails.

    Science.gov (United States)

    Czaczkes, Tomer J; Grüter, Christoph; Jones, Sam M; Ratnieks, Francis L W

    2012-01-01

    The common garden ant Lasius niger use both trail pheromones and memory of past visits to navigate to and from food sources. In a recent paper we demonstrated a synergistic effect between route memory and trail pheromones: the presence of trail pheromones results in experienced ants walking straighter and faster. We also found that experienced ants leaving a pheromone trail deposit less pheromone. Here we focus on another finding of the experiment: the presence of cuticular hydrocarbons (CHCs), which are used as home range markers by ants, also affects pheromone deposition behavior. When walking on a trail on which CHCs are present but trail pheromones are not, experienced foragers deposit less pheromone on the outward journey than on the return journey. The regulatory mechanisms ants use during foraging and recruitment behavior is subtle and complex, affected by multiple interacting factors such as route memory, travel direction and the presence trail pheromone and home-range markings.

  8. Adaptive Levy walks in foraging fallow deer.

    Directory of Open Access Journals (Sweden)

    Stefano Focardi

    Full Text Available BACKGROUND: Lévy flights are random walks, the step lengths of which come from probability distributions with heavy power-law tails, such that clusters of short steps are connected by rare long steps. Lévy walks maximise search efficiency of mobile foragers. Recently, several studies raised some concerns about the reliability of the statistical analysis used in previous analyses. Further, it is unclear whether Lévy walks represent adaptive strategies or emergent properties determined by the interaction between foragers and resource distribution. Thus two fundamental questions still need to be addressed: the presence of Lévy walks in the wild and whether or not they represent a form of adaptive behaviour. METHODOLOGY/PRINCIPAL FINDINGS: We studied 235 paths of solitary and clustered (i.e. foraging in group fallow deer (Dama dama, exploiting the same pasture. We used maximum likelihood estimation for discriminating between a power-tailed distribution and the exponential alternative and rank/frequency plots to discriminate between Lévy walks and composite Brownian walks. We showed that solitary deer perform Lévy searches, while clustered animals did not adopt that strategy. CONCLUSION/SIGNIFICANCE: Our demonstration of the presence of Lévy walks is, at our knowledge, the first available which adopts up-to-date statistical methodologies in a terrestrial mammal. Comparing solitary and clustered deer, we concluded that the Lévy walks of solitary deer represent an adaptation maximising encounter rates with forage resources and not an epiphenomenon induced by a peculiar food distribution.

  9. Spatiotemporal resource distribution and foraging strategies of ants (Hymenoptera: Formicidae)

    Science.gov (United States)

    Lanan, Michele

    2014-01-01

    The distribution of food resources in space and time is likely to be an important factor governing the type of foraging strategy used by ants. However, no previous systematic attempt has been made to determine whether spatiotemporal resource distribution is in fact correlated with foraging strategy across the ants. In this analysis, I present data compiled from the literature on the foraging strategy and food resource use of 402 species of ants from across the phylogenetic tree. By categorizing the distribution of resources reported in these studies in terms of size relative to colony size, spatial distribution relative to colony foraging range, frequency of occurrence in time relative to worker life span, and depletability (i.e., whether the colony can cause a change in resource frequency), I demonstrate that different foraging strategies are indeed associated with specific spatiotemporal resource attributes. The general patterns I describe here can therefore be used as a framework to inform predictions in future studies of ant foraging behavior. No differences were found between resources collected via short-term recruitment strategies (group recruitment, short-term trails, and volatile recruitment), whereas different resource distributions were associated with solitary foraging, trunk trails, long-term trail networks, group raiding, and raiding. In many cases, ant species use a combination of different foraging strategies to collect diverse resources. It is useful to consider these foraging strategies not as separate options but as modular parts of the total foraging effort of a colony. PMID:25525497

  10. Spatiotemporal resource distribution and foraging strategies of ants (Hymenoptera: Formicidae).

    Science.gov (United States)

    Lanan, Michele

    2014-01-01

    The distribution of food resources in space and time is likely to be an important factor governing the type of foraging strategy used by ants. However, no previous systematic attempt has been made to determine whether spatiotemporal resource distribution is in fact correlated with foraging strategy across the ants. In this analysis, I present data compiled from the literature on the foraging strategy and food resource use of 402 species of ants from across the phylogenetic tree. By categorizing the distribution of resources reported in these studies in terms of size relative to colony size, spatial distribution relative to colony foraging range, frequency of occurrence in time relative to worker life span, and depletability (i.e., whether the colony can cause a change in resource frequency), I demonstrate that different foraging strategies are indeed associated with specific spatiotemporal resource attributes. The general patterns I describe here can therefore be used as a framework to inform predictions in future studies of ant foraging behavior. No differences were found between resources collected via short-term recruitment strategies (group recruitment, short-term trails, and volatile recruitment), whereas different resource distributions were associated with solitary foraging, trunk trails, long-term trail networks, group raiding, and raiding. In many cases, ant species use a combination of different foraging strategies to collect diverse resources. It is useful to consider these foraging strategies not as separate options but as modular parts of the total foraging effort of a colony.

  11. Effect of interactions between harvester ants on forager decisions

    Directory of Open Access Journals (Sweden)

    Jacob D Davidson

    2016-10-01

    Full Text Available Harvester ant colonies adjust their foraging activity to day-to-day changes in food availability and hour-to-hour changes in environmental conditions. This collective behavior is regulated through interactions, in the form of brief antennal contacts, between outgoing foragers and returning foragers with food. Here we consider how an ant, waiting in the entrance chamber just inside the nest entrance, uses its accumulated experience of interactions to decide whether to leave the nest to forage. Using videos of field observations, we tracked the interactions and foraging decisions of ants in the entrance chamber. Outgoing foragers tended to interact with returning foragers at higher rates than ants that returned to the deeper nest and did not forage. To provide a mechanistic framework for interpreting these results, we develop a decision model in which ants make decisions based upon a noisy accumulation of individual contacts with returning foragers. The model can reproduce core trends and realistic distributions for individual ant interaction statistics, and suggests possible mechanisms by which foraging activity may be regulated at an individual ant level.

  12. Utilisation of intensive foraging zones by female Australian fur seals.

    Directory of Open Access Journals (Sweden)

    Andrew J Hoskins

    Full Text Available Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search. For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity 'hot spots' were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a

  13. Utilisation of intensive foraging zones by female Australian fur seals.

    Science.gov (United States)

    Hoskins, Andrew J; Costa, Daniel P; Arnould, John P Y

    2015-01-01

    Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search). For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour) determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity 'hot spots' were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a foraging patch.

  14. Utilisation of Intensive Foraging Zones by Female Australian Fur Seals

    Science.gov (United States)

    Hoskins, Andrew J.; Costa, Daniel P.; Arnould, John P. Y.

    2015-01-01

    Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search). For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour) determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity ‘hot spots’ were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a foraging patch

  15. Salt preferences of honey bee water foragers.

    Science.gov (United States)

    Lau, Pierre W; Nieh, James C

    2016-03-01

    The importance of dietary salt may explain why bees are often observed collecting brackish water, a habit that may expose them to harmful xenobiotics. However, the individual salt preferences of water-collecting bees were not known. We measured the proboscis extension reflex (PER) response of Apis mellifera water foragers to 0-10% w/w solutions of Na, Mg and K, ions that provide essential nutrients. We also tested phosphate, which can deter foraging. Bees exhibited significant preferences, with the most PER responses for 1.5-3% Na and 1.5% Mg. However, K and phosphate were largely aversive and elicited PER responses only for the lowest concentrations, suggesting a way to deter bees from visiting contaminated water. We then analyzed the salt content of water sources that bees collected in urban and semi-urban environments. Bees collected water with a wide range of salt concentrations, but most collected water sources had relatively low salt concentrations, with the exception of seawater and swimming pools, which had >0.6% Na. The high levels of PER responsiveness elicited by 1.5-3% Na may explain why bees are willing to collect such salty water. Interestingly, bees exhibited high individual variation in salt preferences: individual identity accounted for 32% of variation in PER responses. Salt specialization may therefore occur in water foragers.

  16. BIOACCUMULATION OF HEAVY METALS IN FORAGE GRASSES

    Directory of Open Access Journals (Sweden)

    Adam Łukowski

    2017-02-01

    Full Text Available The aim of this study was estimation of bioaccumulation of heavy metals (Pb, Ni, Cu, Zn, Cd in forage grasses from the area of Podlasie Province based on the bioaccumulation factor. In the soil samples the pH, organic carbon content and CEC were determined. Determination of heavy metals contents in plant and soil material was carried out by flame atomic absorption spectrometry. Soils were characterized mainly by acidic reaction, high cation exchange capacity and organic carbon content. The content of heavy metals in studied forage grasses did not exceed the polish regulations related to plant usage for feeding purposes, except the lead content in seven samples. Coefficients of variation for particular heavy metals content in studied forage grasses were as follows: Pb - 37%, Ni - 63%, Cu - 30%, Zn - 34%, Cd - 48%. The highest bioaccumulation factor was found for nickel and grass from the village Remieńkiń (11.54, while the lowest for cadmium and grass from the village Jemieliste (0.04.

  17. Polydomy enhances foraging performance in ant colonies.

    Science.gov (United States)

    Stroeymeyt, N; Joye, P; Keller, L

    2017-04-26

    Collective foraging confers benefits in terms of reduced predation risk and access to social information, but it heightens local competition when resources are limited. In social insects, resource limitation has been suggested as a possible cause for the typical decrease in per capita productivity observed with increasing colony size, a phenomenon known as Michener's paradox. Polydomy (distribution of a colony's brood and workers across multiple nests) is believed to help circumvent this paradox through its positive effect on foraging efficiency, but there is still little supporting evidence for this hypothesis. Here, we show experimentally that polydomy enhances the foraging performance of food-deprived Temnothorax nylanderi ant colonies via several mechanisms. First, polydomy influences task allocation within colonies, resulting in faster retrieval of protein resources. Second, communication between sister nests reduces search times for far away resources. Third, colonies move queens, brood and workers across available nest sites in response to spatial heterogeneities in protein and carbohydrate resources. This suggests that polydomy represents a flexible mechanism for space occupancy, helping ant colonies adjust to the environment. © 2017 The Author(s).

  18. Heterosis and heterotic patterns among maize landraces for forage

    Directory of Open Access Journals (Sweden)

    Lopez Cesar Gabriel

    2009-01-01

    Full Text Available Corn silage is a high-quality forage crop used in many areas of the world. Although vegetative and reproductivecomponents of the plant must be considered, breeding programs in temperate regions are mainly based on the Reid xLancaster heterotic pattern that has undergone several cycles of improvement for grain yield. Moreover, hybrids selected forforage production are early maturing genotypes not adapted to warm-temperate or subtropical areas. Consequently, exoticgermplasm should be considered as a source of materials for breeding programs. Eight landraces were crossed following adiallel mating design. Interpopulation crosses showed high heterosis for ear, stover, and whole plant dry matter yield (EY, SY,and WY, respectively. On average, crosses had higher SY than checks, but lower EY. Considering WY, two interpopulationcrosses had higher means than all commercial checks, indicating the potential of the germplasm evaluated. Two compositeswere selected and different breeding strategies are discussed.

  19. Return rates from intertidal foraging from Blombos Cave to Pinnacle Point: Understanding early human economies.

    Science.gov (United States)

    De Vynck, Jan C; Anderson, Robert; Atwater, Chloe; Cowling, Richard M; Fisher, Erich C; Marean, Curtis W; Walker, Robert S; Hill, Kim

    2016-03-01

    The south coast of South Africa provides the earliest evidence for Middle Stone Age (MSA) coastal resource exploitation by early Homo sapiens. In coastal archaeology worldwide, there has been a debate over the general productivity of intertidal foraging, leading to studies that directly measure productivity in some regions, but there have been no such studies in South Africa. Here we present energetic return rate estimates for intertidal foraging along the southern coast of South Africa from Blombos Cave to Pinnacle Point. Foraging experiments were conducted with Khoi-San descendants of the region, and hourly caloric return rates for experienced foragers were measured on 41 days near low tide and through three seasons over two study years. On-site return rates varied as a function of sex, tidal level, marine habitat type and weather conditions. The overall energetic return rate from the entire sample (1492 kcal h(-1)) equals or exceeds intertidal returns reported from other hunter-gatherer studies, as well as measured return rates for activities as diverse as hunting mammals and plant collecting. Returns are projected to be exceptionally high (∼ 3400 kcal h(-1) for men, ∼ 1900 kcal h(-1) for women) under the best combination of conditions. However, because of the monthly tidal cycle, high return foraging is only possible for about 10 days per month and for only 2-3 h on those days. These experiments suggest that while intertidal resources are attractive, women and children could not have subsisted independently, nor met all their protein-lipid needs from marine resources alone, and would have required substantial additional energy and nutrients from plant gathering and/or from males contributing game.

  20. Estimating Radiological Doses to Predators Foraging in a Low-Level Radioactive Waste Management Area

    Energy Technology Data Exchange (ETDEWEB)

    L.Soholt; G.Gonzales; P.Fresquez; K.Bennett; E.Lopez

    2003-03-01

    Since 1957, Los Alamos National Laboratory has operated Area G as its low-level, solid radioactive waste management and disposal area. Although the waste management area is developed, plants, small mammals, and avian and mammalian predators still occupy the less disturbed and revegetated portions of the land. For almost a decade, we have monitored the concentrations of selected radionuclides in soils, plants, and small mammals at Area G. The radionuclides tritium, plutonium-238, and plutonium-239 are regularly found at levels above regional background in all three media. Based on radionuclide concentrations in mice collected from 1994 to 1999, we calculated doses to higher trophic levels (owl, hawk, kestrel, and coyote) that forage on the waste management area. These predators play important functions in the regional ecosystems and are an important part of local Native American traditional tales that identify the uniqueness of their culture. The estimated doses are compared to Department of Energy's interim limit of 0.1 rad/day for the protection of terrestrial wildlife. We used exposure parameters that were derived from the literature for each receptor, including Environmental Protection Agency's exposure factors handbook. Estimated doses to predators ranged from 9E-06 to 2E-04 rad/day, assuming that they forage entirely on the waste management area. These doses are greater than those calculated for predators foraging exclusively in reference areas, but are still well below the interim dose limit. We believe that these calculated doses represent upper-bound estimates of exposure for local predators because the larger predators forage over areas that are much greater than the 63-acre waste management area. Based on these results, we concluded that predators foraging on this area do not face a hazard from radiological exposure under current site conditions.

  1. Forage quality declines with rising temperatures, with implications for livestock production and methane emissions

    Science.gov (United States)

    Lee, Mark A.; Davis, Aaron P.; Chagunda, Mizeck G. G.; Manning, Pete

    2017-03-01

    Livestock numbers are increasing to supply the growing demand for meat-rich diets. The sustainability of this trend has been questioned, and future environmental changes, such as climate change, may cause some regions to become less suitable for livestock. Livestock and wild herbivores are strongly dependent on the nutritional chemistry of forage plants. Nutrition is positively linked to weight gains, milk production and reproductive success, and nutrition is also a key determinant of enteric methane production. In this meta-analysis, we assessed the effects of growing conditions on forage quality by compiling published measurements of grass nutritive value and combining these data with climatic, edaphic and management information. We found that forage nutritive value was reduced at higher temperatures and increased by nitrogen fertiliser addition, likely driven by a combination of changes to species identity and changes to physiology and phenology. These relationships were combined with multiple published empirical models to estimate forage- and temperature-driven changes to cattle enteric methane production. This suggested a previously undescribed positive climate change feedback, where elevated temperatures reduce grass nutritive value and correspondingly may increase methane production by 0.9 % with a 1 °C temperature rise and 4.5 % with a 5 °C rise (model average), thus creating an additional climate forcing effect. Future methane production increases are expected to be largest in parts of North America, central and eastern Europe and Asia, with the geographical extent of hotspots increasing under a high emissions scenario. These estimates require refinement and a greater knowledge of the abundance, size, feeding regime and location of cattle, and the representation of heat stress should be included in future modelling work. However, our results indicate that the cultivation of more nutritious forage plants and reduced livestock farming in warming regions

  2. Liming and plant aging influence on micronutrient uptake by Brachiaria decumbens forage

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria Jose A.; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: marmelin@ipen.br; Primavesi, Odo; Primavesi, Ana C. [EMBRAPA, Sao Carlos, SP (Brazil). Centro de Pecuaria do Sudeste (CPPSE)], E-mail: odo@cppse.embrapa.br

    2007-07-01

    Brachiaria decumbens is the main forage in pastures of several Brazilian regions. The effects of liming and plant age on micronutrient uptake by the forage of a degraded Brachiaria decumbens pasture under restoration process, were studied in Sao Carlos - SP, southeastern Brazil, under altitude tropical climate. Experimental design was a random block (100 m{sup 2}), with 6 replications and 3 treatments. Each block received the following treatment: 0 t/ha of limestone with NK; 2 t/ha of limestone applied on soil surface with NK and maintenance of 1 t/ha per annum; 8 t/ha of limestone applied once on soil surface with NK. Forage samples were collected 14 cm above soil surface, each 36 days in the rain season. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine the micronutrient content. In some cases, Co Fe, Mn and Zn were negatively affected by increasing limestone doses. The opposite effect was observed for Cl. Decreases of Cl, Co and Mo uptake in forage were enhanced with plant aging. (author)

  3. Importance of the 2014 Colorado River Delta pulse flow for migratory songbirds: Insights from foraging behavior

    Science.gov (United States)

    Darrah, Abigail J.; Greeney, Harold F.; Van Riper, Charles

    2017-01-01

    The Lower Colorado River provides critical riparian areas in an otherwise arid region and is an important stopover site for migrating landbirds. In order to reverse ongoing habitat degradation due to drought and human-altered hydrology, a pulse flow was released from Morelos Dam in spring of 2014, which brought surface flow to dry stretches of the Colorado River in Mexico. To assess the potential effects of habitat modification resulting from the pulse flow, we used foraging behavior of spring migrants from past and current studies to assess the relative importance of different riparian habitats. We observed foraging birds in 2000 and 2014 at five riparian sites along the Lower Colorado River in Mexico to quantify prey attack rates, prey attack maneuvers, vegetation use patterns, and degree of preference for fully leafed-out or flowering plants. Prey attack rate was highest in mesquite (Prosopis spp.) in 2000 and in willow (Salix gooddingii) in 2014; correspondingly, migrants predominantly used mesquite in 2000 and willow in 2014 and showed a preference for willows in flower or fruit in 2014. Wilson’s warbler (Cardellina pusilla) used relatively more low-energy foraging maneuvers in willow than in tamarisk (Tamarix spp.) or mesquite. Those patterns in foraging behavior suggest native riparian vegetation, and especially willow, are important resources for spring migrants along the lower Colorado River. Willow is a relatively short-lived tree dependent on spring floods for dispersal and establishment and thus spring migrants are likely to benefit from controlled pulse flows.

  4. Chinstrap penguin foraging area associated with a seamount in Bransfield Strait, Antarctica

    Science.gov (United States)

    Kokubun, Nobuo; Lee, Won Young; Kim, Jeong-Hoon; Takahashi, Akinori

    2015-12-01

    Identifying marine features that support high foraging performance of predators is useful to determine areas of ecological importance. This study aimed to identify marine features that are important for foraging of chinstrap penguins (Pygoscelis antarcticus), an abundant upper-trophic level predator in the Antarctic Peninsula region. We investigated the foraging locations of penguins breeding on King George Island using GPS-depth loggers. Tracking data from 18 birds (4232 dives), 11 birds (2095 dives), and 19 birds (3947 dives) were obtained in 2007, 2010, and 2015, respectively. In all three years, penguins frequently visited an area near a seamount (Orca Seamount) in Bransfield Strait. The percentage of dives (27.8% in 2007, 36.1% in 2010, and 19.1% in 2015) and depth wiggles (27.1% in 2007, 37.2% in 2010, and 22.3% in 2015) performed in this area was higher than that expected from the size of the area and distance from the colony (8.4% for 2007, 14.7% for 2010, and 6.3% for 2015). Stomach content analysis showed that the penguins fed mainly on Antarctic krill. These results suggest that the seamount provided a favorable foraging area for breeding chinstrap penguins, with high availability of Antarctic krill, possibly related to local upwelling.

  5. Thermodynamic properties of water desorption of forage turnip seeds

    OpenAIRE

    Kelly Aparecida Sousa; Osvaldo Resende; André Luis Duarte Goneli; Thaís Adriana de Souza Smaniotto; Daniel Emanuel Cabral de Oliveira

    2014-01-01

    The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip  seeds. The equilibrium moisture content of forage turnip  seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within ...

  6. Thermodynamic properties of water desorption of forage turnip seeds

    OpenAIRE

    Sousa,Kelly Aparecida de; Resende,Osvaldo; Goneli, André Luis Duarte; Smaniotto,Thaís Adriana de Souza; Oliveira,Daniel Emanuel Cabral de

    2015-01-01

    The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip seeds. The equilibrium moisture content of forage turnip seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within th...

  7. Information Foraging Theory: A Framework for Intelligence Analysis

    Science.gov (United States)

    2014-11-01

    Applying information foraging theory to ntelligence analysis This section lays out a plan for the application of IFT to the military...psychologist, 53(5), 533. [24] Wells, V. K. (2012). Foraging: An ecology model of consumer behaviour ? Marketing Theory , 12,117-136. [25] Mantovani, G. (2001...discrete information sources, and the use of semantic cues to enhance the search process. A plan for the application of Information Foraging Theory to the

  8. Interactions between shoal size and conformity in guppy social foraging

    OpenAIRE

    Day, R.L.; MacDonald, T; Brown, C.; Laland, K.N.; Reader, S.M.

    2001-01-01

    Previous experimental studies have established that shoaling fish forage more effectively in large than small groups. We investigated how shoal size affects the foraging efficiency of laboratory populations of the guppy, Poecilia reticulata, exposed to different foraging tasks. Experiment 1 confirmed the prediction that in open water the first fish and focal fish of larger shoals locate food faster than in smaller shoals. However, a second experiment, in which shoals of fish were required to ...

  9. Application of genomics to forage crop breeding for quality traits

    DEFF Research Database (Denmark)

    Lübberstedt, Thomas

    2007-01-01

    Forage quality depends on the digestibility of fodder, and can be directly measured by the intake and metabolic conversion in animal trials. However, animal trials are time-consuming, laborious, and thus expensive. It is not possible to study thousands of plant genotypes, as required in breeding...... studied in detail and sequence motifs with likely effect on forage quality have been identified by association studies. Moreover, transgenic approaches substantiated the effect of several of these genes on forage quality. Perspectives and limitations of these findings for forage crop breeding...

  10. Adaptive collective foraging in groups with conflicting nutritional needs

    Science.gov (United States)

    Senior, Alistair M.; Lihoreau, Mathieu; Charleston, Michael A.; Buhl, Jerome; Raubenheimer, David; Simpson, Stephen J.

    2016-01-01

    Collective foraging, based on positive feedback and quorum responses, is believed to improve the foraging efficiency of animals. Nutritional models suggest that social information transfer increases the ability of foragers with closely aligned nutritional needs to find nutrients and maintain a balanced diet. However, whether or not collective foraging is adaptive in a heterogeneous group composed of individuals with differing nutritional needs is virtually unexplored. Here we develop an evolutionary agent-based model using concepts of nutritional ecology to address this knowledge gap. Our aim was to evaluate how collective foraging, mediated by social retention on foods, can improve nutrient balancing in individuals with different requirements. The model suggests that in groups where inter-individual nutritional needs are unimodally distributed, high levels of collective foraging yield optimal individual fitness by reducing search times that result from moving between nutritionally imbalanced foods. However, where nutritional needs are highly bimodal (e.g. where the requirements of males and females differ) collective foraging is selected against, leading to group fission. In this case, additional mechanisms such as assortative interactions can coevolve to allow collective foraging by subgroups of individuals with aligned requirements. Our findings indicate that collective foraging is an efficient strategy for nutrient regulation in animals inhabiting complex nutritional environments and exhibiting a range of social forms. PMID:27152206

  11. Adaptive collective foraging in groups with conflicting nutritional needs.

    Science.gov (United States)

    Senior, Alistair M; Lihoreau, Mathieu; Charleston, Michael A; Buhl, Jerome; Raubenheimer, David; Simpson, Stephen J

    2016-04-01

    Collective foraging, based on positive feedback and quorum responses, is believed to improve the foraging efficiency of animals. Nutritional models suggest that social information transfer increases the ability of foragers with closely aligned nutritional needs to find nutrients and maintain a balanced diet. However, whether or not collective foraging is adaptive in a heterogeneous group composed of individuals with differing nutritional needs is virtually unexplored. Here we develop an evolutionary agent-based model using concepts of nutritional ecology to address this knowledge gap. Our aim was to evaluate how collective foraging, mediated by social retention on foods, can improve nutrient balancing in individuals with different requirements. The model suggests that in groups where inter-individual nutritional needs are unimodally distributed, high levels of collective foraging yield optimal individual fitness by reducing search times that result from moving between nutritionally imbalanced foods. However, where nutritional needs are highly bimodal (e.g. where the requirements of males and females differ) collective foraging is selected against, leading to group fission. In this case, additional mechanisms such as assortative interactions can coevolve to allow collective foraging by subgroups of individuals with aligned requirements. Our findings indicate that collective foraging is an efficient strategy for nutrient regulation in animals inhabiting complex nutritional environments and exhibiting a range of social forms.

  12. Suboptimal foraging behavior: a new perspective on gambling.

    Science.gov (United States)

    Addicott, Merideth A; Pearson, John M; Kaiser, Nicole; Platt, Michael L; McClernon, F Joseph

    2015-10-01

    Why do people gamble? Conventional views hold that gambling may be motivated by irrational beliefs, risk-seeking, impulsive temperament, or dysfunction within the same reward circuitry affected by drugs of abuse. An alternate, unexplored perspective is that gambling is an extension of natural foraging behavior to a financial environment. However, when these foraging algorithms are applied to stochastic gambling outcomes, undesirable results may occur. To test this hypothesis, we recruited participants based on their frequency of gambling-yearly (or less), monthly, and weekly-and investigated how gambling frequency related to irrational beliefs, risk-taking/impulsivity, and foraging behavior. We found that increased gambling frequency corresponded to greater gambling-related beliefs, more exploratory choices on an explore/exploit foraging task, and fewer points earned on a Patchy Foraging Task. Gambling-related beliefs negatively related to performance on the Patchy Foraging Task, indicating that individuals with more gambling-related cognitions tended to leave a patch too quickly. This indicates that frequent gamblers have reduced foraging ability to maximize rewards; however, gambling frequency -and by extension, poor foraging ability- was not related to risk-taking or impulsive behavior. These results suggest that gambling reflects the application of a dysfunctional foraging process to financial outcomes.

  13. Enumeration and Identification of Nitrogen-Fixing Bacteria from Forage Grass Roots

    OpenAIRE

    Wright, Sara F.; Weaver, R. W.

    1981-01-01

    Root-soil cores were collected from forage grasses growing in a subtropical region of Texas and tested for acetylene reduction activity. The population density of nitrogen-fixing bacteria was measured, using various media and incubation conditions. Bacteria were confirmed as nitrogen fixing, using the acetylene reduction assay, and were classified according to standard biochemical and cultural methods. The majority of the nitrogen-fixing bacteria isolated from roots were Enterobacter cloacae ...

  14. Identification and characterisation of foraging areas of seabirds in upwelling systems: biological and hydrographic implications for foraging at sea

    OpenAIRE

    Ludynia, Katrin

    2007-01-01

    This thesis investigates the foraging behaviour of three seabird species, the African penguin (Spheniscus demersus) and the Cape gannet (Morus capensis) in the Benguela upwelling system as well as the Peruvian booby (Sula variegata) in the Humboldt Current. Biological and hydrographic parameters were considered when evaluating the characteristics of foraging areas and the behaviour of the species studied. Foraging areas used by the birds as well as the birds' diving behaviour were assessed by...

  15. Foraging modality and plasticity in foraging traits determine the strength of competitive interactions among carnivorous plants, spiders and toads.

    Science.gov (United States)

    Jennings, David E; Krupa, James J; Rohr, Jason R

    2016-07-01

    Foraging modalities (e.g. passive, sit-and-wait, active) and traits are plastic in some species, but the extent to which this plasticity affects interspecific competition remains unclear. Using a long-term laboratory mesocosm experiment, we quantified competition strength and the plasticity of foraging traits in a guild of generalist predators of arthropods with a range of foraging modalities. Each mesocosm contained eight passively foraging pink sundews, and we employed an experimental design where treatments were the presence or absence of a sit-and-wait foraging spider and actively foraging toad crossed with five levels of prey abundance. We hypothesized that actively foraging toads would outcompete the other species at low prey abundance, but that spiders and sundews would exhibit plasticity in foraging traits to compensate for strong competition when prey were limited. Results generally supported our hypotheses. Toads had a greater effect on sundews at low prey abundances, and toad presence caused spiders to locate webs higher above the ground. Additionally, the closer large spider webs were to the ground, the greater the trichome densities produced by sundews. Also, spider webs were larger with than without toads and as sundew numbers increased, and these effects were more prominent as resources became limited. Finally, spiders negatively affected toad growth only at low prey abundance. These findings highlight the long-term importance of foraging modality and plasticity of foraging traits in determining the strength of competition within and across taxonomic kingdoms. Future research should assess whether plasticity in foraging traits helps to maintain coexistence within this guild and whether foraging modality can be used as a trait to reliably predict the strength of competitive interactions. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  16. Foraging behaviour of King Penguins ( Aptenodytes patagonicus) in relation to predictable mesoscale oceanographic features in the Polar Front Zone to the north of South Georgia

    Science.gov (United States)

    Scheffer, Annette; Trathan, Philip N.; Collins, Martin

    2010-07-01

    Marine predators are thought to utilise oceanic features adjusting their foraging strategy in a scale-dependent manner. Thus, they are thought to dynamically alter their foraging behaviour in response to environmental conditions encountered. In this study, we examined the foraging behaviour of King Penguins ( Aptenodytes patagonicus) breeding at South Georgia in relation to predictable and stable oceanographic features. We studied penguins during their long post-laying foraging trips during December 2005 and January 2006. For this investigation, we undertook a simultaneous analysis of ARGOS satellite-tracking data and Mk 7 WildLife Computers Time Depth Recorder (TDR) dive data. To investigate correlations between foraging behaviour and oceanographic conditions, we used SST data from January 2006 from MODIS satellite AQUA. To determine changes in search effort, first passage time (FPT) was calculated; for analysis of dive behaviour, we used several dive parameters that are thought to be reliable indicators of changes in foraging behaviour. King Penguins appeared to target predictable mesoscale features in the Polar Front Zone (PFZ), either a warm-core eddy in the PFZ or regions of strong temperature gradients at oceanic fronts. Two different trip types could be distinguished: direct trips with a straight path to one foraging area at the edge of an eddy or at a thermal front, and circular trips where birds foraged along strong thermal gradients at the northern limit of the PFZ. It is likely that both trip types were a direct consequence of prey encounter rates and distributions, both of which are likely to be associated with these oceanographic features. Circular trips often included passages across the centre of an eddy where birds made deep foraging dives, but remained only a short time in the eddy, possibly because prey were too deep. All birds showed Area Restricted Search (ARS) at scales of exploit the environment and adjust their foraging strategy and diving

  17. Foraging behaviour of the exotic wasp Vespula germanica (Hymenoptera: Vespidae) on a native caterpillar defoliator.

    Science.gov (United States)

    Pietrantuono, A L; Moreyra, S; Lozada, M

    2017-09-19

    Vespula germanica is a social wasp and an opportunistic predator. While foraging, these wasps learn and integrate different kinds of cues. They have successfully invaded many parts of the world, including native Nothofagus and Lophozonia forests located in the Andean-Patagonian region, where they forage on native arthropods. Perzelia arda, a lepidopteron defoliator of Lophozonia obliqua, uses the foliage to hide in and feed on. The purpose of this work is to study whether V. germanica use olfactory cues when foraging on P. arda. To do this, we used a Y-tube olfactometer and established three treatments to compare pairs of all combinations of stimuli (larvae, leaves with larval traces, and leaves without larval traces) and controls. Data were analysed via two developed models that showed decisions made by V. germanica and allowed to establish a scale of preferences between the stimuli. The analysis demonstrates that V. germanica wasps choose P. arda as larval prey and are capable of discriminating between the offered stimuli (deviance information criterion (DIC) null model = 873.97; DIC simple model = 84.5, n = 152). According to the preference scale, V. germanica preferred leaves with traces of larvae, suggesting its ability to associate these traces with the presence of the prey. This may be because, under natural conditions, larvae are never exposed outside their shelters of leaves and therefore V. germanica uses indirect signals. The presence of V. germanica foraging on P. arda highlights the flexible foraging behaviour of this wasp which may also act as a positive biological control, reducing lepidopteran populations.

  18. People of the ancient rainforest: late Pleistocene foragers at the Batadomba-lena rockshelter, Sri Lanka.

    Science.gov (United States)

    Perera, Nimal; Kourampas, Nikos; Simpson, Ian A; Deraniyagala, Siran U; Bulbeck, David; Kamminga, Johan; Perera, Jude; Fuller, Dorian Q; Szabó, Katherine; Oliveira, Nuno V

    2011-09-01

    Batadomba-lena, a rockshelter in the rainforest of southwestern Sri Lanka, has yielded some of the earliest evidence of Homo sapiens in South Asia. H. sapiens foragers were present at Batadomba-lena from ca. 36,000 cal BP to the terminal Pleistocene and Holocene. Human occupation was sporadic before the global Last Glacial Maximum (LGM). Batadomba-lena's Late Pleistocene inhabitants foraged for a broad spectrum of plant and mainly arboreal animal resources (monkeys, squirrels and abundant rainforest snails), derived from a landscape that retained equatorial rainforest cover through periods of pronounced regional aridity during the LGM. Juxtaposed hearths, palaeofloors with habitation debris, postholes, excavated pits, and animal and plant remains, including abundant Canarium nutshells, reflect intensive habitation of the rockshelter in times of monsoon intensification and biome reorganisation after ca. 16,000 cal BP. This period corresponds with further broadening of the economic spectrum, evidenced though increased contribution of squirrels, freshwater snails and Canarium nuts in the diet of the rockshelter occupants. Microliths are more abundant and morphologically diverse in the earliest, pre-LGM layer and decline markedly during intensified rockshelter use on the wane of the LGM. We propose that changing toolkits and subsistence base reflect changing foraging practices, from shorter-lived visits of highly mobile foraging bands in the period before the LGM, to intensified use of Batadomba-lena and intense foraging for diverse resources around the site during and, especially, following the LGM. Traces of ochre, marine shell beads and other objects from an 80 km-distant shore, and, possibly burials reflect symbolic practices from the outset of human presence at the rockshelter. Evidence for differentiated use of space (individual hearths, possible habitation structures) is present in LGM and terminal Pleistocene layers. The record of Batadomba-lena demonstrates

  19. Complex scaling behavior in animal foraging patterns

    Science.gov (United States)

    Premachandra, Prabhavi Kaushalya

    This dissertation attempts to answer questions from two different areas of biology, ecology and neuroscience, using physics-based techniques. In Section 2, suitability of three competing random walk models is tested to describe the emergent movement patterns of two species of primates. The truncated power law (power law with exponential cut off) is the most suitable random walk model that characterizes the emergent movement patterns of these primates. In Section 3, an agent-based model is used to simulate search behavior in different environments (landscapes) to investigate the impact of the resource landscape on the optimal foraging movement patterns of deterministic foragers. It should be noted that this model goes beyond previous work in that it includes parameters such as spatial memory and satiation, which have received little consideration to date in the field of movement ecology. When the food availability is scarce in a tropical forest-like environment with feeding trees distributed in a clumped fashion and the size of those trees are distributed according to a lognormal distribution, the optimal foraging pattern of a generalist who can consume various and abundant food types indeed reaches the Levy range, and hence, show evidence for Levy-flight-like (power law distribution with exponent between 1 and 3) behavior. Section 4 of the dissertation presents an investigation of phase transition behavior in a network of locally coupled self-sustained oscillators as the system passes through various bursting states. The results suggest that a phase transition does not occur for this locally coupled neuronal network. The data analysis in the dissertation adopts a model selection approach and relies on methods based on information theory and maximum likelihood.

  20. Forage Polyphenol Oxidase and Ruminant Livestock Nutrition

    Directory of Open Access Journals (Sweden)

    Michael Richard F. Lee

    2014-12-01

    Full Text Available Polyphenol oxidase (PPO is associated with the detrimental effect of browning fruit and vegetables, however interest within PPO containing forage crops has grown since the brownng reaction was associated with reduced nitrogen (N losses in silo and the rumen. The reduction in protein breakdown in silo of red clover (high PPO forage increased the quality of protein, improving N-use efficiency (NUE when fed to ruminants. A further benefit of red clover silage feeding is a significant reduction in lipolysis in silo and an increase in the deposition of beneficial C18 polyunsaturated fatty acid (PUFA in animal products, which has also been linked to PPO activity. PPOs protection of plant protein and glycerol based-PUFA in silo is related to the deactivation of plant proteases and lipases. This deactivation occurs through PPO catalysing the conversion of diphenols to quinones which bind with cellular nucleophiles such as protein reforming a protein-bound phenol (PBP. If the protein is an enzyme the complexing denatures the enzyme. However, PPO is inactive in the anaerobic rumen and therefore any subsequent protection of plant protein and glycerol based-PUFA in the rumen must be as a result of events that occurred to the forage pre-ingestion. Reduced activity of plant proteases and lipases would have little effect on NUE and glycerol based-PUFA in the rumen due to the greater concentration of rumen microbial proteases and lipases. The mechanism for PPOs protection of plant protein in the rumen is a consequence of complexing plant protein, rather than protease deactivation per se. These complexed proteins reduce protein digestibility in the rumen and subsequently increase un-degraded dietary protein flow to the small intestine. The mechanism for protecting glycerol-based PUFA has yet to be fully elucidated but may be associated with entrapment within PBP reducing access to microbial lipases or differences in rumen digestion kinetics of red clover.

  1. Forager Polymorphism and Foraging Ecology in the Leaf-Cutting Ant, Atta colombica

    Directory of Open Access Journals (Sweden)

    James K. Wetterer

    1995-01-01

    workers are smaller and do not appear to be so specialized as soldiers as are A. cephalotes maxima workers. The broader size-range of workers participating in foraging appears to allow A. colombica to exploit a wider range of resources than A. cephalotes, including tougher, denser vegetation and fallen fruits.

  2. Temporal effects of hunting on foraging behavior of an apex predator: Do bears forego foraging when risk is high?

    Science.gov (United States)

    Hertel, Anne G; Zedrosser, Andreas; Mysterud, Atle; Støen, Ole-Gunnar; Steyaert, Sam M J G; Swenson, Jon E

    2016-12-01

    Avoiding predators most often entails a food cost. For the Scandinavian brown bear (Ursus arctos), the hunting season coincides with the period of hyperphagia. Hunting mortality risk is not uniformly distributed throughout the day, but peaks in the early morning hours. As bears must increase mass for winter survival, they should be sensitive to temporal allocation of antipredator responses to periods of highest risk. We expected bears to reduce foraging activity at the expense of food intake in the morning hours when risk was high, but not in the afternoon, when risk was low. We used fine-scale GPS-derived activity patterns during the 2 weeks before and after the onset of the annual bear hunting season. At locations of probable foraging, we assessed abundance and sugar content, of bilberry (Vaccinium myrtillus), the most important autumn food resource for bears in this area. Bears decreased their foraging activity in the morning hours of the hunting season. Likewise, they foraged less efficiently and on poorer quality berries in the morning. Neither of our foraging measures were affected by hunting in the afternoon foraging bout, indicating that bears did not allocate antipredator behavior to times of comparably lower risk. Bears effectively responded to variation in risk on the scale of hours. This entailed a measurable foraging cost. The additive effect of reduced foraging activity, reduced forage intake, and lower quality food may result in poorer body condition upon den entry and may ultimately reduce reproductive success.

  3. Fatty acid composition of forage herb species

    DEFF Research Database (Denmark)

    Warner, D.; Jensen, Søren Krogh; Cone, J.W.

    2010-01-01

    The use of alternative forage species in grasslands for intensive livestock production is receiving renewed attention. Data on fatty acid composition of herbs are scarce, so four herbs (Plantago lanceolata, Achillea millefolium, Cichorium intybus, Pastinaca sativa) and one grass species (timothy......, Phleum pratense) were sown in a cutting trial. The chemical composition and concentration of fatty acids (FA) of individual species were determined during the growing season. Concentrations of crude protein and FA were generally higher in the herbs than in timothy. C. intybus had the highest nutritive...

  4. Forage polyphenol oxidase and ruminant livestock nutrition.

    Science.gov (United States)

    Lee, Michael R F

    2014-01-01

    Polyphenol oxidase (PPO) is predominately associated with the detrimental effect of browning fruit and vegetables, however, interest within PPO containing forage crops (crops to be fed to animals) has grown since the browning reaction was associated with reduced nitrogen (N) losses in silo and the rumen. The reduction in protein breakdown in silo of red clover (high PPO forage) increased the quality of protein, improving N-use efficiency [feed N into product N (e.g., Milk): NUE] when fed to ruminants. A further benefit of red clover silage feeding is a significant reduction in lipolysis (cleaving of glycerol-based lipid) in silo and an increase in the deposition of beneficial C18 polyunsaturated fatty acid (PUFA) in animal products, which has also been linked to PPO activity. PPOs protection of plant protein and glycerol based-PUFA in silo is related to the deactivation of plant proteases and lipases. This deactivation occurs through PPO catalyzing the conversion of diphenols to quinones which bind with cellular nucleophiles such as protein reforming a protein-bound phenol (PBP). If the protein is an enzyme (e.g., protease or lipase) the complexing denatures the enzyme. However, PPO is inactive in the anaerobic rumen and therefore any subsequent protection of plant protein and glycerol based-PUFA in the rumen must be as a result of events that occurred to the forage pre-ingestion. Reduced activity of plant proteases and lipases would have little effect on NUE and glycerol based-PUFA in the rumen due to the greater concentration of rumen microbial proteases and lipases. The mechanism for PPOs protection of plant protein in the rumen is a consequence of complexing plant protein, rather than protease deactivation per se. These complexed proteins reduce protein digestibility in the rumen and subsequently increase undegraded dietary protein flow to the small intestine. The mechanism for protecting glycerol-based PUFA has yet to be fully elucidated but may be associated

  5. 75 FR 68321 - Forage Genetics International; Supplemental Request for Partial Deregulation of Roundup Ready...

    Science.gov (United States)

    2010-11-05

    ... Animal and Plant Health Inspection Service Forage Genetics International; Supplemental Request for... ``partial deregulation'' from Forage Genetics International for the planting, harvesting, and movement... submitted to the Agency from Forage Genetics International requesting a ``partial deregulation.'' ADDRESSES...

  6. Ant Foraging As an Indicator of Tropical Dry Forest Restoration.

    Science.gov (United States)

    Hernández-Flores, J; Osorio-Beristain, M; Martínez-Garza, C

    2016-08-01

    Variation in foraging behavior may indicate differences in food availability and allow assessment of restoration actions. Ants are prominent bioindicators used in assessing ecological responses to disturbance. However, behavioral data have been poorly incorporated as an index. The foraging performance of red harvester ants was quantified in order to evaluate the success of a restoration ecology experiment in the tropical dry forest of Sierra de Huautla, Morelos, in central Mexico. Foraging performance by granivorous, Pogonomyrmex barbatus, ants was diminished after 6 and 8 years of cattle grazing and wood harvest were excluded as part of a restoration experiment in a highly degraded biome. Despite investing more time in foraging, ant colonies in exclusion plots showed lower foraging success and acquired less seed biomass than colonies in control plots. In line with the predictions of optimal foraging theory, in restored plots where ant foraging performance was poor, ants harvested a higher diversity of seeds. Reduced foraging success and increased harvest of non-preferred foods in exclusion plots were likely due to the growth of herbaceous vegetation, which impedes travel by foragers. Moreover, by 8 years of exclusion, 37% of nests in exclusion plots had disappeared compared to 0% of nests in control plots. Ants' foraging success and behavior were sensitive to changes in habitat quality due to the plant successional process triggered by a restoration intervention. This study spotlights on the utility of animal foraging behavior in the evaluation of habitat restoration programs. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Urban gardens promote bee foraging over natural habitats and plantations.

    Science.gov (United States)

    Kaluza, Benjamin F; Wallace, Helen; Heard, Tim A; Klein, Alexandra-Maria; Leonhardt, Sara D

    2016-03-01

    Increasing human land use for agriculture and housing leads to the loss of natural habitat and to widespread declines in wild bees. Bee foraging dynamics and fitness depend on the availability of resources in the surrounding landscape, but how precisely landscape related resource differences affect bee foraging patterns remains unclear. To investigate how landscape and its interaction with season and weather drive foraging and resource intake in social bees, we experimentally compared foraging activity, the allocation of foragers to different resources (pollen, nectar, and resin) and overall resource intake in the Australian stingless bee Tetragonula carbonaria (Apidae, Meliponini). Bee colonies were monitored in different seasons over two years. We compared foraging patterns and resource intake between the bees' natural habitat (forests) and two landscapes differently altered by humans (suburban gardens and agricultural macadamia plantations). We found foraging activity as well as pollen and nectar forager numbers to be highest in suburban gardens, intermediate in forests and low in plantations. Foraging patterns further differed between seasons, but seasonal variations strongly differed between landscapes. Sugar and pollen intake was low in plantations, but contrary with our predictions, it was even higher in gardens than in forests. In contrast, resin intake was similar across landscapes. Consequently, differences in resource availability between natural and altered landscapes strongly affect foraging patterns and thus resource intake in social bees. While agricultural monocultures largely reduce foraging success, suburban gardens can increase resource intake well above rates found in natural habitats of bees, indicating that human activities can both decrease and increase the availability of resources in a landscape and thus reduce or enhance bee fitness.

  8. Forage mass and the nutritive value of pastures mixed with forage peanut and red clover

    Directory of Open Access Journals (Sweden)

    Ricardo Lima de Azevedo Junior

    2012-04-01

    Full Text Available The objective of this research was to estimate three pasture-based systems mixed with elephantgrass + spontaneous growth species, annual ryegrass, for pasture-based system 1; elephantgrass + spontaneous growth species + forage peanut, for pasture-based system 2; and elephantgrass + spontaneous growth species + annual ryegrass + red clover, for pasture-based system 3. Elephantgrass was planted in rows 4 m apart from each other. During the cool-season, annual ryegrass was sown in the alleys between the rows of elephantgrass; forage peanut and red clover were sown in the alleys between the elephantgrass according to the respective treatment. The experimental design was totally randomized in the three treatments (pasture-based systems, two replicates (paddocks in completely split-plot time (grazing cycles. Holstein cows receiving 5.5 kg-daily complementary concentrate feed were used in the evaluation. Pre-grazing forage mass, botanical composition and stocking rate were evaluated. Samples of simulated grazing were collected to analyze organic matter (OM, neutral detergent fiber (NDF, crude protein (CP and organic matter in situ digestibility (OMISD. Nine grazing cycles were performed during the experimental period (341 days. The average dry matter values for pre-grazing and stocking rate were 3.34; 3.46; 3.79 t/ha, and 3.28; 3.34; 3.60 AU/ha for each respective pasture-based system. Similar results were observed between the pasture-based systems for OM, NDF, CP and OMISD. Considering forage mass, stocking rate and nutritive value, the pasture-based system intercropped with forage legumes presented better performance.

  9. Nitrate leaching from sandy loam soils under a double-cropping forage system estimated from suction-probe measurements.

    NARCIS (Netherlands)

    Trindade, H.; Coutinho, J.; Beusichem, van M.L.; Scholefield, D.; Moreira, N.

    1997-01-01

    Nitrate leaching from a double-cropping forage system was measured over a 2-year period (June 1994–May 1996) in the Northwest region of Portugal using ceramic cup samplers. The crops were grown for silage making and include maize (from May to September) and a winter crop (rest of the year)

  10. Comparative metabolite fingerprinting of the rumen system during colonisation of three forage grass (Lolium perenne L. varieties.

    Directory of Open Access Journals (Sweden)

    Alison H Kingston-Smith

    Full Text Available The rumen microbiota enable ruminants to degrade complex ligno-cellulosic compounds to produce high quality protein for human consumption. However, enteric fermentation by domestic ruminants generates negative by-products: greenhouse gases (methane and environmental nitrogen pollution. The current lack of cultured isolates representative of the totality of rumen microbial species creates an information gap about the in vivo function of the rumen microbiota and limits our ability to apply predictive biology for improvement of feed for ruminants. In this work we took a whole ecosystem approach to understanding how the metabolism of the microbial population responds to introduction of its substrate. Fourier Transform Infra Red (FTIR spectroscopy-based metabolite fingerprinting was used to discriminate differences in the plant-microbial interactome of the rumen when using three forage grass varieties (Lolium perenne L. cv AberDart, AberMagic and Premium as substrates for microbial colonisation and fermentation. Specific examination of spectral regions associated with fatty acids, amides, sugars and alkanes indicated that although the three forages were apparently similar by traditional nutritional analysis, patterns of metabolite flux within the plant-microbial interactome were distinct and plant genotype dependent. Thus, the utilisation pattern of forage nutrients by the rumen microbiota can be influenced by subtleties determined by forage genotypes. These data suggest that our interactomic approach represents an important means to improve forages and ultimately the livestock environment.

  11. Challenges and opportunities for improving eco-efficiency of tropical forage-based systems to mitigate greenhouse gas emissions

    Directory of Open Access Journals (Sweden)

    Michael Peters

    2013-12-01

    Full Text Available Forage-based livestock production plays a key role in national and regional economies, for food security and poverty alleviation, but is considered a major contributor to agricultural GHG emissions. While demand for livestock products is predicted to increase, there is political and societal pressure both to reduce environmental impacts and to convert some of the pasture area to alternative uses, such as crop production and environmental conservation. Thus, it is essential to develop approaches for sustainable intensification of livestock systems to mitigate GHG emissions, addressing biophysical, socio-economic and policy challenges. This paper highlights the potential of improved tropical forages, linked with policy incentives, to enhance livestock production, while reducing its environmental footprint. Emphasis is on crop-livestock systems. We give examples for sustainable intensification to mitigate GHG emissions, based on improved forages in Brazil and Colombia, and suggest future perspectives.

  12. Challenges and opportunities for improving eco-efficiency of tropical forage-based systems to mitigate greenhouse gas emissions

    Directory of Open Access Journals (Sweden)

    Michael Peters

    2013-12-01

    Full Text Available Forage-based livestock production plays a key role in national and regional economies, for food security and poverty alleviation, but is considered a major contributor to agricultural GHG emissions. While demand for livestock products is predicted to increase, there is political and societal pressure both to reduce environmental impacts and to convert some of the pasture area to alternative uses, such as crop production and environmental conservation. Thus, it is essential to develop approaches for sustainable intensification of livestock systems to mitigate GHG emissions, addressing biophysical, socio-economic and policy challenges. This paper highlights the potential of improved tropical forages, linked with policy incentives, to enhance livestock production, while reducing its environmental footprint. Emphasis is on crop-livestock systems. We give examples for sustainable intensification to mitigate GHG emissions, based on improved forages in Brazil and Colombia, and suggest future perspectives.

  13. Elevation and forest clearing effects on foraging differ between surface--and subterranean--foraging army ants (Formicidae: Ecitoninae).

    Science.gov (United States)

    Kumar, Anjali; O'Donnell, Sean

    2009-01-01

    1. Forest fragmentation often results in a matrix of open areas mixed with patches of forest. Both biotic and abiotic factors can affect consumer species' ability to utilize the altered habitat, especially for species that range over large areas searching for prey. 2. Army ants (Formicidae: Ecitoninae) are highly mobile top predators in terrestrial Neotropical ecosystems. Army ant foraging behaviour is influenced by forest clearing at lowland sites, and clearing can reduce army ant population persistence. 3. Because high temperatures are implicated in hindering above-ground army ant foraging, we predicted that forest clearing effects on army ant foraging would be reduced at higher (cooler) elevations in montane forest. We also predicted that subterranean foraging, employed by some army ant species, would buffer them from the negative effects of forest clearing. 4. We quantified the foraging rates of above-ground and underground foraging army ants at eight sites along an elevational gradient from 1090 to 1540 m a.s.l. We asked whether these two foraging strategies cause a difference in the ability of army ants to forage in open matrix areas relative to elevationally matched forested habitats, and whether elevation predicts open area vs. forest foraging rate differences. 5. As predicted, army ants that forage above-ground had lower foraging rates in open areas, but the open area vs. forest difference declined with elevation. In contrast, underground foragers were not affected by habitat type, and underground foraging rates increased with elevation. Ground surface temperatures were higher in open areas than forested areas. Temperatures declined with elevation, and temperature differences between open and forested areas decreased with elevation. 6. We conclude that army ants that forage above-ground may be restricted to forested areas due to a thermal tolerance threshold, but that they are released from this limitation at higher elevations. We further suggest that

  14. Modeling ventilation time in forage tower silos.

    Science.gov (United States)

    Bahloul, A; Chavez, M; Reggio, M; Roberge, B; Goyer, N

    2012-10-01

    The fermentation process in forage tower silos produces a significant amount of gases, which can easily reach dangerous concentrations and constitute a hazard for silo operators. To maintain a non-toxic environment, silo ventilation is applied. Literature reviews show that the fermentation gases reach high concentrations in the headspace of a silo and flow down the silo from the chute door to the feed room. In this article, a detailed parametric analysis of forced ventilation scenarios built via numerical simulation was performed. The methodology is based on the solution of the Navier-Stokes equations, coupled with transport equations for the gas concentrations. Validation was achieved by comparing the numerical results with experimental data obtained from a scale model silo using the tracer gas testing method for O2 and CO2 concentrations. Good agreement was found between the experimental and numerical results. The set of numerical simulations made it possible to establish a simple analytical model to predict the minimum time required to ventilate a silo to make it safe to enter. This ventilation time takes into account the headspace above the forage, the airflow rate, and the initial concentrations of O2 and CO2. The final analytical model was validated with available results from the literature.

  15. Threshold foraging behavior of baleen whales

    Science.gov (United States)

    Piatt, John F.; Methven, David A.

    1992-01-01

    We conducted hydroacoustic surveys for capelin Mallotus villosus in Witless Bay, Newfoundland, Canada, on 61 days during the summers of 1983 to 1985. On 32 of those days in whlch capelin surveys were conducted, we observed a total of 129 baleen whales - Including 93 humpback Megaptera novaeangliae, 31 minke Balaenoptera acutorostrata and 5 fin whales B. phvsalus. Although a few whales were observed when capelin schools were scarce, the majority (96%) of whales were observed when mean daily capelin densities exceeded 5 schools per linear km surveyed (range of means over 3 yr: 0.0 to 14.0 schools km-1). Plots of daily whale abundance (no. h-1 surveyed) vs daily capelin school density (mean no. schools km-1 surveyed) in each summer revealed that baleen whales have a threshold foraging response to capelin density. Thresholds were estimated using a simple itterative step-function model. Foraging thresholds of baleen whales (7.3, 5.0, and 5.8 schools km-1) varied between years in relation to the overall abundance of capelin schools in the study area during summer (means of 7.2, 3.3, and 5.3 schools km-1, respectively).

  16. N response of no-till dryland winter triticale forage

    Science.gov (United States)

    Triticale’s forage-yield response to fertilizer nitrogen (N) is impressive on soils testing low in available N. Our objective is to quantify the forage yield response of dryland winter triticale to applied N and to residual NO3-N. A second objective is to fit the yield data to a regression equation ...

  17. Yield and forage nutritive value of reduced lignin alfalfa

    Science.gov (United States)

    Reduced lignin alfalfa (Medicago sativa L.) cultivars have the potential to increase the feeding value of alfalfa for livestock by improving the forage fiber digestibility and to increase harvest management flexibility. The objectives were to compare the yield and forage nutritive value of reduced ...

  18. Group foraging by a stream minnow: shoals or aggregations?

    Science.gov (United States)

    Freeman, Mary C.; Grossman, G.D.

    1992-01-01

    The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosyside dace, Clinostomus funduloides. Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to increased threat of predation by a seasonally occurring predator. Dace also rarely avoided conspecifics, except when an aggressive individual defended a foraging site. Otherwise, there was little evidence of exploitative competition among dace for drifting prey or of foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.

  19. Promoting Interactive Learning: A Classroom Exercise to Explore Foraging Strategies

    Science.gov (United States)

    Beaumont, Ellen S.; Rowe, Graham; Mikhaylov, Natalie S.

    2012-01-01

    We describe a classroom exercise to allow students to explore foraging strategies in higher vertebrates. The exercise includes an initial interactive session in which students act as predators and are guided through foraging simulations, and a subsequent student-led session where classmates are employed as experimental subjects. Students rated the…

  20. Experience, corpulence and decision making in ant foraging.

    Science.gov (United States)

    Robinson, Elva J H; Feinerman, Ofer; Franks, Nigel R

    2012-08-01

    Social groups are structured by the decisions of their members. Social insects typically divide labour: some decide to stay in the nest while others forage for the colony. Two sources of information individuals may use when deciding whether to forage are their own experience of recent task performance and their own physiology, e.g. fat reserves (corpulence). The former is primarily personal information; the latter may give an indication of the food reserves of the whole colony. These factors are hard to separate because typically leaner individuals are also more experienced foragers. We designed an experiment to determine whether foraging specialisation is physiological or experience based (or both). We invented a system of automatic doors controlled by radio-tag information to manipulate task access and decouple these two sources of information. Our results show that when information from corpulence and recent experience conflict, ants behave only in accordance with their corpulence. However, among ants physiologically inclined to forage (less corpulent ants), recent experience of success positively influenced their propensity to forage again. Hence, foraging is organised via long-term physiological differences among individuals resulting in a relatively stable response threshold distribution, with fine-tuning provided by short-term learning processes. Through these simple rules, colonies can organise their foraging effort both robustly and flexibly.

  1. Children's Play and Culture Learning in an Egalitarian Foraging Society

    Science.gov (United States)

    Boyette, Adam H.

    2016-01-01

    Few systematic studies of play in foragers exist despite their significance for understanding the breadth of contexts for human development and the ontogeny of cultural learning. Forager societies lack complex social hierarchies, avenues for prestige or wealth accumulation, and formal educational institutions, and thereby represent a contrast to…

  2. Auto-Clustering using Particle Swarm Optimization and Bacterial Foraging

    DEFF Research Database (Denmark)

    Rutkowski Olesen, Jakob; Cordero, Jorge; Zeng, Yifeng

    2009-01-01

    This paper presents a hybrid approach for clustering based on particle swarm optimization (PSO) and bacteria foraging algorithms (BFA). The new method AutoCPB (Auto-Clustering based on particle bacterial foraging) makes use of autonomous agents whose primary objective is to cluster chunks of data...

  3. Promoting Interactive Learning: A Classroom Exercise to Explore Foraging Strategies

    Science.gov (United States)

    Beaumont, Ellen S.; Rowe, Graham; Mikhaylov, Natalie S.

    2012-01-01

    We describe a classroom exercise to allow students to explore foraging strategies in higher vertebrates. The exercise includes an initial interactive session in which students act as predators and are guided through foraging simulations, and a subsequent student-led session where classmates are employed as experimental subjects. Students rated the…

  4. Potential for sorghum forages for dairy heifers in the midwest

    Science.gov (United States)

    Dairy heifers have lower dietary energy needs than lactating cows (63-65% TDN for 6-12 month old heifers; 58-60% TDN for >12 month old heifers), but forage-based diets containing significant amounts of corn silage often exceed the needs of pregnant heifers. Use of low-energy forages to decrease ener...

  5. Mixed cropping studies in Leucaena under intensive forage production systems

    Energy Technology Data Exchange (ETDEWEB)

    Gill, A.S.; Patil, B.D.

    1983-01-01

    Trials were established during 1982 at the Indian Grassland and Fodder Research Institute in which Leucaena (leucocephala), Sesbania (sesban) and Desmanthus (virgatus) were interplanted with the perennial cereals hybrid napier No. 3 and guinea grass. Forage yield from shrubs growth without cereal was greatest with Sesbania (710 q/ha). The greatest forage yield was obtained with Leucaena + hybrid napier (875 q/ha).

  6. Female mice respond differently to costly foraging versus food restriction

    NARCIS (Netherlands)

    Schubert, Kristin A.; Vaanholt, Lobke M.; Stavasius, Fanny; Demas, Gregory E.; Daan, Serge; Visser, G. Henk

    2008-01-01

    Experimental manipulation of foraging costs per food reward can be used to study the plasticity of physiological systems involved in energy metabolism. This approach is useful for understanding adaptations to natural variation in food availability. Earlier studies have shown that animals foraging on

  7. Nutritional status influences socially regulated foraging ontogeny in honey bees.

    Science.gov (United States)

    Toth, Amy L; Kantarovich, Sara; Meisel, Adam F; Robinson, Gene E

    2005-12-01

    In many social insects, including honey bees, worker energy reserve levels are correlated with task performance in the colony. Honey bee nest workers have abundant stored lipid and protein while foragers are depleted of these reserves; this depletion precedes the shift from nest work to foraging. The first objective of this study was to test the hypothesis that lipid depletion has a causal effect on the age at onset of foraging in honey bees (Apis mellifera L.). We found that bees treated with a fatty acid synthesis inhibitor (TOFA) were more likely to forage precociously. The second objective of this study was to determine whether there is a relationship between social interactions, nutritional state and behavioral maturation. Since older bees are known to inhibit the development of young bees into foragers, we asked whether this effect is mediated nutritionally via the passage of food from old to young bees. We found that bees reared in social isolation have low lipid stores, but social inhibition occurs in colonies in the field, whether young bees are starved or fed. These results indicate that although social interactions affect the nutritional status of young bees, social and nutritional factors act independently to influence age at onset of foraging. Our findings suggest that mechanisms linking internal nutritional physiology to foraging in solitary insects have been co-opted to regulate altruistic foraging in a social context.

  8. Comparative sucrose responsiveness in Apis mellifera and A. cerana foragers.

    Science.gov (United States)

    Yang, Wenchao; Kuang, Haiou; Wang, Shanshan; Wang, Jie; Liu, Wei; Wu, Zhenhong; Tian, Yuanyuan; Huang, Zachary Y; Miao, Xiaoqing

    2013-01-01

    In the European honey bee, Apis mellifera, pollen foragers have a higher sucrose responsiveness than nectar foragers when tested using a proboscis extension response (PER) assay. In addition, Africanized honey bees have a higher sucrose responsiveness than European honey bees. Based on the biology of the Eastern honey bee, A. cerana, we hypothesized that A. cerana should also have a higher responsiveness to sucrose than A. mellifera. To test this hypothesis, we compared the sucrose thresholds of pollen foragers and nectar foragers in both A. cerana and A. mellifera in Fujian Province, China. Pollen foragers were more responsive to sucrose than nectar foragers in both species, consistent with previous studies. However, contrary to our hypothesis, A. mellifera was more responsive than A. cerana. We also demonstrated that this higher sucrose responsiveness in A. mellifera was not due to differences in the colony environment by co-fostering two species of bees in the same mixed-species colonies. Because A. mellifera foragers were more responsive to sucrose, we predicted that their nectar foragers should bring in less concentrated nectar compared to that of A. cerana. However, we found no differences between the two species. We conclude that A. cerana shows a different pattern in sucrose responsiveness from that of Africanized bees. There may be other mechanisms that enable A. cerana to perform well in areas with sparse nectar resources.

  9. Linking foraging decisions to residential yard bird composition.

    Directory of Open Access Journals (Sweden)

    Susannah B Lerman

    Full Text Available Urban bird communities have higher densities but lower diversity compared with wildlands. However, recent studies show that residential urban yards with native plantings have higher native bird diversity compared with yards with exotic vegetation. Here we tested whether landscape designs also affect bird foraging behavior. We estimated foraging decisions by measuring the giving-up densities (GUD; amount of food resources remaining when the final forager quits foraging on an artificial food patch, i.e seed trays in residential yards in Phoenix, AZ, USA. We assessed how two yard designs (mesic: lush, exotic vegetation; xeric: drought-tolerant and native vegetation differed in foraging costs. Further, we developed a statistical model to calculate GUDs for every species visiting the seed tray. Birds foraging in mesic yards depleted seed trays to a lower level (i.e. had lower GUDs compared to birds foraging in xeric yards. After accounting for bird densities, the lower GUDs in mesic yards appeared largely driven by invasive and synanthropic species. Furthermore, behavioral responses of individual species were affected by yard design. Species visiting trays in both yard designs had lower GUDs in mesic yards. Differences in resource abundance (i.e., alternative resources more abundant and of higher quality in xeric yards contributed to our results, while predation costs associated with foraging did not. By enhancing the GUD, a common method for assessing the costs associated with foraging, our statistical model provided insights into how individual species and bird densities influenced the GUD. These differences we found in foraging behavior were indicative of differences in habitat quality, and thus our study lends additional support for native landscapes to help reverse the loss of urban bird diversity.

  10. Linking foraging decisions to residential yard bird composition.

    Science.gov (United States)

    Lerman, Susannah B; Warren, Paige S; Gan, Hilary; Shochat, Eyal

    2012-01-01

    Urban bird communities have higher densities but lower diversity compared with wildlands. However, recent studies show that residential urban yards with native plantings have higher native bird diversity compared with yards with exotic vegetation. Here we tested whether landscape designs also affect bird foraging behavior. We estimated foraging decisions by measuring the giving-up densities (GUD; amount of food resources remaining when the final forager quits foraging on an artificial food patch, i.e seed trays) in residential yards in Phoenix, AZ, USA. We assessed how two yard designs (mesic: lush, exotic vegetation; xeric: drought-tolerant and native vegetation) differed in foraging costs. Further, we developed a statistical model to calculate GUDs for every species visiting the seed tray. Birds foraging in mesic yards depleted seed trays to a lower level (i.e. had lower GUDs) compared to birds foraging in xeric yards. After accounting for bird densities, the lower GUDs in mesic yards appeared largely driven by invasive and synanthropic species. Furthermore, behavioral responses of individual species were affected by yard design. Species visiting trays in both yard designs had lower GUDs in mesic yards. Differences in resource abundance (i.e., alternative resources more abundant and of higher quality in xeric yards) contributed to our results, while predation costs associated with foraging did not. By enhancing the GUD, a common method for assessing the costs associated with foraging, our statistical model provided insights into how individual species and bird densities influenced the GUD. These differences we found in foraging behavior were indicative of differences in habitat quality, and thus our study lends additional support for native landscapes to help reverse the loss of urban bird diversity.

  11. Breeding limits foraging time : evidence of interrupted foraging response from body mass variation in a tropical environment

    NARCIS (Netherlands)

    Nwaogu, Chima J.; Dietz, Maurine W.; Tieleman, B. Irene; Cresswell, Will

    2017-01-01

    Birds should store body reserves if starvation risk is anticipated; this is known as an ‘interrupted foraging response’. If foraging remains unrestricted, however, body mass should remain low to limit the predation risk that gaining and carrying body reserves entails. In temperate environments mass

  12. Foraging in Semantic Fields: How We Search Through Memory.

    Science.gov (United States)

    Hills, Thomas T; Todd, Peter M; Jones, Michael N

    2015-07-01

    When searching for concepts in memory--as in the verbal fluency task of naming all the animals one can think of--people appear to explore internal mental representations in much the same way that animals forage in physical space: searching locally within patches of information before transitioning globally between patches. However, the definition of the patches being searched in mental space is not well specified. Do we search by activating explicit predefined categories (e.g., pets) and recall items from within that category (categorical search), or do we activate and recall a connected sequence of individual items without using categorical information, with each item recalled leading to the retrieval of an associated item in a stream (associative search), or both? Using semantic representations in a search of associative memory framework and data from the animal fluency task, we tested competing hypotheses based on associative and categorical search models. Associative, but not categorical, patch transitions took longer to make than position-matched productions, suggesting that categorical transitions were not true transitions. There was also clear evidence of associative search even within categorical patch boundaries. Furthermore, most individuals' behavior was best explained by an associative search model without the addition of categorical information. Thus, our results support a search process that does not use categorical information, but for which patch boundaries shift with each recall and local search is well described by a random walk in semantic space, with switches to new regions of the semantic space when the current region is depleted.

  13. Sea otter foraging behavior and hydrocarbon levels in prey

    Science.gov (United States)

    Doroff, Angela M.; Bodkin, James L.; Loughlin, Thomas R.

    1994-01-01

    Following the Exxon Valdez oil spill (EVOS), Prudhoe Bay crude oil from the vessel spread on the sea surface and covered coastal shores from western Prince William Sound (PWS) to the Alaska Peninsula. In PWS alone. acute mortality of sca otters at the time of the spill was estimated to be greater than 2000 (Doroff et al. 1993; Garrott et al. 1993).Shoreline oiling was observed on approximately 24% of the 1891 km of coastline surveyed within PWS (Exxon Valdez Oil Spill Damage Assessment Geoprocessing Group 1991). The effect of oil on the abundance of nearshore marine invertebrate populations is unclear, and the concentration and persistence of hydrocarbons present in tissues of most of these invertebrate species still remains unknown. What is known is that marine bivalves can accumulate petroleum hydrocarbons from both chronic and acute sources (Blumer et al. 1970; Ehrhardt 1972; Boehun and Quinn 1977). Potential long-term chronic effects of oiled intertidal and subtidal prey on the sea otter population are of concern.Sea otters prey on a wide variety of benthic marine invertebrates (Riedman and Estes 1990) and forage in shallow coastal waters (Wild and Arnes 1974), which vary widely in exposure to the open ocean, substrate type, and community composition. Sea otters have high metabolic demands relative to other marine mammals and can consume 20-25% of their body weight per day in invertebrate prey (Kenyon 1969: Costa and Kooyman 1984). Sca otters have occupied southwestern PWS since at least the early 1950s (Lensink 1962; Garshelis et al. 1986). The sea otter population in the PWS spill region was likely near equilibrium density and limited by prey availability before the oil spill (xcurrel (Estes et al. 1981; Garshelis et al. 1986; Johnson 1987). Sea otters in this region spent 59% of the daylight hours foraging, while otters in recently reoccupied habitats of eastern PWS spent only 27%. (Garshelis et al. 1986). Therefore, small differences in abundance of prey

  14. Seed softening patterns of forage legumes in a temperate/subtropical environment in Uruguay

    Directory of Open Access Journals (Sweden)

    Javier Do Canto

    2013-03-01

    Full Text Available Few studies have been conducted in annual and perennial forage legumes to investigate the development of hardseededness and the subsequent pattern of seed softening in temperate and subtropical regions of South America. Experiments were conducted during 2007 and 2008 in central Uruguay to follow the pattern of seed softening in 35 annual and perennial forage legumes, including three native species of Uruguay and five commercial cultivars. Newly ripened seeds of each plant material were placed in mesh packets on the soil surface in mid-summer. Samples were recovered monthly for germination tests and the proportion of residual hard seeds determined. The native species Adesmia bicolor (Poir. DC., Adesmia securigerifolia Herter, and Ornithopus micranthus (Benth. Arechav., together with Ornithopus pinnatus (Mill. Druce cv. INIA Molles behaved similarly. They showed high levels of initial hard seed from 78% in A. bicolor to 99% in A. securigerifolia and O. pinnatus cv. INIA Molles in 2007; displayed pulses of seed softening, particularly in autumn, and retained moderate levels of residual hard seed for the development of a soil seed bank ranging from 15% in A. bicolor to 49% in O. micranthus. These appear to be desirable characteristics for persistence of forage legumes in subtropical grasslands, both for annual and perennial species. Trifolium repens L. and Lotus corniculatus L. produced few hard seeds, only 2% and 13% respectively were hard after 1-mo in the field and were completely soft by July placing extra reliance on their vegetative propagation for persistence. Materials of L. arenarius Brot. showed pronounced late autumn softening, while materials of L. ornithopodioides L. showed extremely high levels of hardseededness (between 96% and 100% and no softening during the evaluation period, apart from two materials that were completely soft seeded. Mediterranean forage legumes should be properly evaluated in temperate and subtropical regions as

  15. Space use by foragers consuming renewable resources

    Science.gov (United States)

    Abramson, Guillermo; Kuperman, Marcelo N.; Morales, Juan M.; Miller, Joel C.

    2014-05-01

    We study a simple model of a forager as a walk that modifies a relaxing substrate. Within it simplicity, this provides an insight on a number of relevant and non-intuitive facts. Even without memory of the good places to feed and no explicit cost of moving, we observe the emergence of a finite home range. We characterize the walks and the use of resources in several statistical ways, involving the behavior of the average used fraction of the system, the length of the cycles followed by the walkers, and the frequency of visits to plants. Preliminary results on population effects are explored by means of a system of two non directly interacting animals. Properties of the overlap of home ranges show the existence of a set of parameters that provides the best utilization of the shared resource.

  16. Stature in Holocene foragers of North India.

    Science.gov (United States)

    Lukacs, John R; Pal, J N; Nelson, Greg C

    2014-03-01

    The Ganga Plain of North India provides an archaeological and skeletal record of semi-nomadic Holocene foragers in association with an aceramic Mesolithic culture. Prior estimates of stature for Mesolithic Lake Cultures (MLC) used inappropriate equations from an American White reference group and need revision. Attention is given to intralimb body proportions and geo-climatic provenance of MLC series in considering the most suitable reference population. Regression equations from ancient Egyptians are used in reconstructing stature for MLC skeletal series from Damdama (DDM), Mahadaha (MDH), and Sarai Nahar Rai (SNR). Mean stature is estimated at between 174 (MDH) and 178 cm (DDM and SNR) for males, and between 163 cm (MDH) and 179 cm (SNR) for females. Stature estimates based on ancient Egyptian equations are significantly shorter (from 3.5 to 7.1 cm shorter in males; from 3.2 to 7.5 cm shorter in females) than estimates using the American White reference group. Revised stature estimates from tibia length and from femur + tibia more accurately estimate MLC stature for two reasons: a) these elements are highly correlated with stature and have lower standard estimates of error, and b) uncertainty regarding methods of measuring tibia length is avoided. When compared with Holocene samples of native Americans and Mesolithic Europeans, MLC series from North India are tall. This aspect of their biological variation confirms earlier assessments and results from the synergistic influence of balanced nutrition from broad-spectrum foraging, body-proportions adapted to a seasonally hot and arid climate, and the functional demands of a mobile, semi-nomadic life-style.

  17. Production and transcriptional regulation of proanthocyanidin biosynthesis in forage legumes.

    Science.gov (United States)

    Zhou, Meiliang; Wei, Li; Sun, Zhanmin; Gao, Lihua; Meng, Yu; Tang, Yixiong; Wu, Yanmin

    2015-05-01

    Proanthocyanidins (PA), also known as condensed tannins, contribute to important forage legumes traits including disease resistance and forage quality. PA in forage plants has both positive and negative effects on feed digestibility and animal performance. The analytical methods and their applicability in measuring the contents of PA in forage plants are essential to studies on their nutritional effects. In spite of important breakthroughs in our understanding of the PA biosynthesis, important questions still remain to be answered such as the PA polymerization and transport. Recent advances in the understanding of transcription factor-mediated gene regulation mechanisms in anthocyanin and PA biosynthetic pathway in model plants suggest new approaches for the metabolic engineering of PA in forage plants. The present review will attempt to present the state-of-the-art of research in these areas and provide an update on the production and metabolic engineering of PA in forage plants. We hope that this will contribute to a better understanding of the ways in which PA production to manipulate the content of PA for beneficial effects in forage plants.

  18. Departure time influences foraging associations in little penguins.

    Science.gov (United States)

    Sutton, Grace J; Hoskins, Andrew J; Berlincourt, Maud; Arnould, John P Y

    2017-01-01

    Recent studies have documented that little penguins (Eudyptula minor) associate at sea, displaying synchronised diving behaviour throughout a foraging trip. However, previous observations were limited to a single foraging trip where only a small number of individuals were simultaneously tracked. Consequently, it is not known whether coordinated behaviour is consistent over time, or what factors influence it. In the present study, breeding adults were concurrently instrumented with GPS and dive behaviour data loggers for at least 2 consecutive foraging trips during guard and post-guard stage at two breeding colonies (London Bridge and Gabo Island, south-eastern Australia) of contrasting population size (approximately 100 and 30,000-40,000, respectively). At both colonies, individuals were sampled in areas of comparable nesting density and spatial area. At London Bridge, where individuals use a short (23 m) common pathway from their nests to the shoreline, > 90% (n = 42) of birds displayed foraging associations and 53-60% (n = 20) maintained temporally consistent associations with the same conspecifics. Neither intrinsic (sex, size or body condition) nor extrinsic (nest proximity) factors were found to influence foraging associations. However, individuals that departed from the colony at a similar time were more likely to associate during a foraging trip. At Gabo Island, where individuals use a longer (116 m) pathway with numerous tributaries to reach the shoreline, few individuals (< 31%; n = 13) from neighbouring nests associated at sea and only 1% (n = 1) maintained associations over subsequent trips. However, data from animal-borne video cameras indicated individuals at this colony displayed foraging associations of similar group size to those at London Bridge. This study reveals that group foraging behaviour occurs at multiple colonies and the pathways these individuals traverse with conspecifics may facilitate opportunistic group formation and resulting in

  19. Energetic cost of foraging in free-diving emperor penguins.

    Science.gov (United States)

    Nagy, K A; Kooyman, G L; Ponganis, P J

    2001-01-01

    Hypothesizing that emperor penguins (Aptenodytes forsteri) would have higher daily energy expenditures when foraging for their food than when being hand-fed and that the increased expenditure could represent their foraging cost, we measured field metabolic rates (FMR; using doubly labeled water) over 4-d periods when 10 penguins either foraged under sea ice or were not allowed to dive but were fed fish by hand. Surprisingly, penguins did not have higher rates of energy expenditure when they dove and captured their own food than when they did not forage but were given food. Analysis of time-activity and energy budgets indicated that FMR was about 1.7 x BMR (basal metabolic rate) during the 12 h d(-1) that penguins were lying on sea ice. During the remaining 12 h d(-1), which we termed their "foraging period" of the day, the birds were alert and active (standing, preening, walking, and either free diving or being hand-fed), and their FMR was about 4.1 x BMR. This is the lowest cost of foraging estimated to date among the eight penguin species studied. The calculated aerobic diving limit (ADL(C)), determined with the foraging period metabolic rate of 4.1 x BMR and known O(2) stores, was only 2.6 min, which is far less than the 6-min ADL previously measured with postdive lactate analyses in emperors diving under similar conditions. This indicates that calculating ADL(C) from an at-sea or foraging-period metabolic rate in penguins is not appropriate. The relatively low foraging cost for emperor penguins contributes to their relatively low total daily FMR (2.9 x BMR). The allometric relationship for FMR in eight penguin species, including the smallest and largest living representatives, is kJ d(-1)=1,185 kg(0.705).

  20. Simulation modeling to understand how selective foraging by beaver can drive the structure and function of a willow community

    Science.gov (United States)

    Peinetti, H.R.; Baker, B.W.; Coughenour, M.B.

    2009-01-01

    Beaver-willow (Castor-Salix) communities are a unique and vital component of healthy wetlands throughout the Holarctic region. Beaver selectively forage willow to provide fresh food, stored winter food, and construction material. The effects of this complex foraging behavior on the structure and function of willow communities is poorly understood. Simulation modeling may help ecologists understand these complex interactions. In this study, a modified version of the SAVANNA ecosystem model was developed to better understand how beaver foraging affects the structure and function of a willow community in a simulated riparian ecosystem in Rocky Mountain National Park, Colorado (RMNP). The model represents willow in terms of plant and stem dynamics and beaver foraging in terms of the quantity and quality of stems cut to meet the energetic and life history requirements of beaver. Given a site where all stems were equally available, the model suggested a simulated beaver family of 2 adults, 2 yearlings, and 2 kits required a minimum of 4 ha of willow (containing about10 stems m-2) to persist in a steady-state condition. Beaver created a willow community where the annual net primary productivity (ANPP) was 2 times higher and plant architecture was more diverse than the willow community without beaver. Beaver foraging created a plant architecture dominated by medium size willow plants, which likely explains how beaver can increase ANPP. Long-term simulations suggested that woody biomass stabilized at similar values even though availability differed greatly at initial condition. Simulations also suggested that willow ANPP increased across a range of beaver densities until beaver became food limited. Thus, selective foraging by beaver increased productivity, decreased biomass, and increased structural heterogeneity in a simulated willow community.

  1. Foraging responses of black-legged kittiwakes to prolonged food-shortages around colonies on the Bering Sea shelf.

    Directory of Open Access Journals (Sweden)

    Rosana Paredes

    Full Text Available We hypothesized that changes in southeastern Bering Sea foraging conditions for black-legged kittiwakes (Rissa tridactyla have caused shifts in habitat use with direct implications for population trends. To test this, we compared at-sea distribution, breeding performance, and nutritional stress of kittiwakes in three years (2008-2010 at two sites in the Pribilof Islands, where the population has either declined (St. Paul or remained stable (St. George. Foraging conditions were assessed from changes in (1 bird diets, (2 the biomass and distribution of juvenile pollock (Theragra chalcogramma in 2008 and 2009, and (3 eddy kinetic energy (EKE; considered to be a proxy for oceanic prey availability. In years when biomass of juvenile pollock was low and patchily distributed in shelf regions, kittiwake diets included little or no neritic prey and a much higher occurrence of oceanic prey (e.g. myctophids. Birds from both islands foraged on the nearby shelves, or made substantially longer-distance trips overnight to the basin. Here, feeding was more nocturnal and crepuscular than on the shelf, and often occurred near anticyclonic, or inside cyclonic eddies. As expected from colony location, birds from St. Paul used neritic waters more frequently, whereas birds from St. George typically foraged in oceanic waters. Despite these distinctive foraging patterns, there were no significant differences between colonies in chick feeding rates or fledging success. High EKE in 2010 coincided with a 63% increase in use of the basin by birds from St. Paul compared with 2008 when EKE was low. Nonetheless, adult nutritional stress, which was relatively high across years at both colonies, peaked in birds from St. Paul in 2010. Diminishing food resources in nearby shelf habitats may have contributed to kittiwake population declines at St Paul, possibly driven by increased adult mortality or breeding desertion due to high foraging effort and nutritional stress.

  2. Analysis of lead concentration in forager stingless bees Trigona sp. (hymenoptera: Apidae) and propolis at Cilutung and Maribaya, West Java

    Science.gov (United States)

    Safira, Nabila; Anggraeni, Tjandra

    2015-09-01

    Several studies had shown that lead (Pb) in the environment could accumulate in bees, which in turn could affect the quality of the resulting product. In this study, forager stingless bees (Trigona sp.) and its product (propolis) collected from a stingless bees apiculture. This apiculture had two apiary sites which were distinguished by its environmental setting. Apiary site in Cilutung had a forest region environmental setting, while apiary site in Maribaya was located beside the main road. The objective of this study was to determine the extent of lead concentration in propolis originated from both apiary sites and establish the correlation between lead concentration in propolis and lead level in forager stingless bees. Forager bees and propolis samples were originated from 50 bees colonies (Cilutung) and 44 bees colonies (Maribaya). They were analyzed using AAS-GF (Atomic Absorption Spectrometre-Graphite Furnace) to determine the level of lead concentration. The results showed that the average level of lead in propolis originated from Cilutung (298.08±73.71 ppb) was lower than the average level of lead in forager bees which originated from Maribaya (330.64±156.34 ppb). However, these values did not show significant difference (p>0.05). There was no significant difference (p>0.05) between the average level of lead in forager bees which originated from Cilutung (118.08±30.46 ppb) and Maribaya (128.82±39.66 ppb). However, these values did not show significant difference (p>0.05). In conclusion, the average level of lead concentration in propolis in both sites had passed the maximum permission standard of lead for food in Indonesia. There was no correlation between lead concentration in propolis and forager stingless bees.

  3. A comprehensive approach for assessing the economic contribution of forage and livestock improvement options to smallholder farming enterprises

    Institute of Scientific and Technical Information of China (English)

    Neil MacLeod; Scott Waldron; WEN Shi-lin

    2015-01-01

    The importance of livestock production activities to improving the livelihoods of smal holder farming households and the efifciency of their underlying farming systems is increasingly recognized. A rapid increase in livestock numbers, especial y beef cattle, and special purpose forages is being promoted for smal holder farms which have traditional y undertaken sub-sistence cropping activities or simple livestock rearing activities using low quality feedstuffs. Because limited plantings of specialized forages combined with a poor knowledge of animal nutrition are a chal enge to establishing sustainable livestock enterprises, much public policy and research is now being focused on the use of new forages and improved feeding practices. A number of economic studies have suggested that specialized forage growing and livestock feeding activities can make a positive contribution to smal holder welfare. The studies have typical y compared the total level of farm or household income with and without livestock activities. Little attention is given to how much the new forage or livestock activities actual y contribute to or draw resources from other farm activities to assess their real economic contribution to the enterprise, and the availability of simple tools to assist in making such assessments are limited. This paper describes a simple model ing approach that was developed for an Australian Centre for International Agricultural Research (ACIAR)-supported project to explore the real as opposed to apparent economic impact of integrating improved forages and livestock within smal holder farming systems in the Red Soils region of south-central China. Application of the model is demonstrated using a simple case study of a smal holder enterprise that plans to introduce a new beef cattle rearing activity to its existing farm activity mix. The case study highlights the importance of explicitly valuing transfers of resources between different farm activities to gauge the real

  4. Analysis of lead concentration in forager stingless bees Trigona sp. (hymenoptera: Apidae) and propolis at Cilutung and Maribaya, West Java

    Energy Technology Data Exchange (ETDEWEB)

    Safira, Nabila, E-mail: safira.nabila@ymail.com; Anggraeni, Tjandra, E-mail: tjandra@sith.itb.ac.id [School of Life Science and Technology, Institut Teknologi Bandung – Jalan Ganesha 10, Bandung (Indonesia)

    2015-09-30

    Several studies had shown that lead (Pb) in the environment could accumulate in bees, which in turn could affect the quality of the resulting product. In this study, forager stingless bees (Trigona sp.) and its product (propolis) collected from a stingless bees apiculture. This apiculture had two apiary sites which were distinguished by its environmental setting. Apiary site in Cilutung had a forest region environmental setting, while apiary site in Maribaya was located beside the main road. The objective of this study was to determine the extent of lead concentration in propolis originated from both apiary sites and establish the correlation between lead concentration in propolis and lead level in forager stingless bees. Forager bees and propolis samples were originated from 50 bees colonies (Cilutung) and 44 bees colonies (Maribaya). They were analyzed using AAS-GF (Atomic Absorption Spectrometre–Graphite Furnace) to determine the level of lead concentration. The results showed that the average level of lead in propolis originated from Cilutung (298.08±73.71 ppb) was lower than the average level of lead in forager bees which originated from Maribaya (330.64±156.34 ppb). However, these values did not show significant difference (p>0.05). There was no significant difference (p>0.05) between the average level of lead in forager bees which originated from Cilutung (118.08±30.46 ppb) and Maribaya (128.82±39.66 ppb). However, these values did not show significant difference (p>0.05). In conclusion, the average level of lead concentration in propolis in both sites had passed the maximum permission standard of lead for food in Indonesia. There was no correlation between lead concentration in propolis and forager stingless bees.

  5. Experimental Study of the Dynamics of Foraging Ants

    Science.gov (United States)

    Walker, J. I.; Fetzner, R. P.; Baxter, G. W.

    2006-03-01

    We study the search paths of foraging ants in order to describe their behavior mathematically. Ants have become popular as simple agents in models of artificial life. Here, the ant is presented the problem of finding food when no food cues are present. In this experiment, individual ants (Formicinae lasius flavus) are allowed to forage on a two-dimensional textured surface in the absence of a food source. The position of the ant as a function of time is determined with a high resolution digital camera. The scaling properties of the resulting foraging paths compare favorably with those of certain types of random walk.

  6. The organization of foraging in the fire ant, Solenopsis invicta.

    Science.gov (United States)

    Tschinkel, Walter R

    2011-01-01

    Although natural selection in ants acts most strongly at the colony, or superorganismal level, foraging patterns have rarely been studied at that level, focusing instead on the behavior of individual foragers or groups of foragers. The experiments and observations in this paper reveal in broad strokes how colonies of the fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), allocate their available labor to foraging, how they disperse that force within their territory, and how this force changes with colony size, season and worker age. Territory area is positively related to colony size and the number of foragers, more so during the spring than fall. Changes of colony size and territory area are driven by seasonal variation of sexual and worker production, which in turn drive seasonal variation of worker age-distribution. During spring sexual production, colonies shrink because worker production falls below replacement. This loss is proportional to colony size, causing forager density in the spring to be negatively related to colony and territory size. In the fall, colonies emphasize worker production, bringing colony size back up. However, because smaller colonies curtailed spring worker production less than larger ones, their fall forager populations are proportionally greater, causing them to gain territory at the expense of large colonies. Much variation of territory area remains unexplained and can probably be attributed to pressure from neighboring colonies. Boundaries between territories are characterized by "no ants' zones" mostly devoid of fire ants. The forager population can be divided into a younger group of recruitable workers that wait for scouts to activate them to help retrieve large food finds. About one-third of the recruits wait near openings in the foraging tunnels that underlie the entire territory, while two-thirds wait in the nest. Recruitment to food is initially very rapid and local from the foraging tunnels, while sustained

  7. Grasping complex matter : large herbivore foraging in patches of heterogeneous resources

    NARCIS (Netherlands)

    Drescher, M.F.

    2003-01-01

    Key words: herbivory; functional response; grazing; food intake; food quality; selectivity; cattle; savanna The functional response, defined as the relationship of forage intake with forage availability, is the principal link between a forager and a forage resource, and as such connects the trophic

  8. Grading Index(GI):A New Integrated Technique for Evaluation of Forage Quality

    Institute of Scientific and Technical Information of China (English)

    HU Hong-lian; GAO Min; LU De-xun

    2011-01-01

    Introduction Forage quality can be defined as the extent to which forage has the potential to produce a desired animal response or level of performance,for example,daily gain or milk production.Due to forage quality is a function of both animal and plant factors.It is difficult and complex to completely evaluate forage quality.Recently,

  9. Optimal foraging by birds: feeder-based experiments for secondary and post-secondary students

    Science.gov (United States)

    Optimal foraging theory attempts to explain the foraging patterns observed in animals, including their choice of particular food items and foraging locations. Here, we describe three exercises designed to test hypotheses about food choice and foraging habitat preference using bird feeders. These e...

  10. Performance and economic analyses of year-round forage systems for forage-fed beef production in the Gulf Coast.

    Science.gov (United States)

    Scaglia, G; Rodriguez, J; Gillespie, J; Bhandari, B; Wang, J J; McMillin, K W

    2014-12-01

    On a global scale, most beef is produced from grazing pastures or rangelands. Certain limitations exist, however, such as not having adequate animal rates of gain for marbling and availability of adequate forage nutritional value and quantity for constant animal weight gains. In the last 20 yr, there has been an increased interest in forage-fed beef for multiple reasons (health related, environmental concerns, and welfare issues). Starting on June 5, 13, 14, and 8 in 4 consecutive yr, 54 steers (initial BW=259±5.6 kg; average of 9 mo of age) were randomly allotted to 3 yr-round forage systems. Each system occupied 6 ha/replicate and had the same stocking rate. System 1 had annual ryegrass (Lolium multiflorum) for winter grazing and bermudagrass (Cynodon dactylon) for summer grazing; while Systems 2 and 3 added rye and a clover mix to the ryegrass and diversified the use of pastures in the fall (dallisgrass [Paspalum dilatatum] and clovers [Trifolium spp.]). System 3 added the use of annual summer forages. During their respective growing season for each forage or forage mix, mass and height did not limit animal performance; however, there was a sampling date effect (P0.05) were detected between systems in ADG year round, during the winter season, or carcass characteristics. Return over total direct costs and total specified expenses were greater for Systems 1 and 2, while System 3 was the lowest. Hay making and bale sales played a major role in explaining the economic results of this study. Where possible, year-round forage systems are a viable alternative for forage-fed beef production; however, the low gains during summer and forage availability during the transition period when hay is necessary deserve further research to find alternatives to improve productivity during those times of the year.

  11. Growth and Forage Value of Moringa (Moringa oleifera Lam. under Different Organic Fertilization and Cut Intervals

    Directory of Open Access Journals (Sweden)

    Patrícia Carneiro Souto

    2010-06-01

    Full Text Available The present work was carried out in two UFPB Experimental Stations (NUPEARIDO (Luvissolo Planossólico (Bruno não Cálcico and Lameirão farms (Luvissolo located in the semi-arid region of Brazil, from February to August/2000. Its objective consisted to verify the influence of organic fertilizers (bovine, goat and donkey manures, and organic compost of plants remains and cut intervals (three and six months after seedling planting in the bromatological composition of moringa (Moringa oleifera Lam above ground forage. Planting of 15cm high seedlings took place in February, into 0.30m x 0.30m x 0.30m openings in the soil, arranged in a 1.5m x 1.5m grid, in the beginning of the rainy season. Plants were cut three and six months after planting. Also, new stems were cut three months after the first cutting. Collected materials were analyzed for Dry Matter (DM, Neutral Detergent Fiber (NDF, Acid Detergent Fiber (ADF, Crude Protein (CP, ash and Hemicellulose (HC contents. Forage from six-month-old plants showed an increased HC content when fertilized with bovine or goat manure. Forage from three-month old plants showed different NDF, ADF, PB, and ash contents than the older ones, except for stem DM and HC. Three-month-old moringa sprouts showed higher CP and ash contents than material from three or six month old non-cut plants.

  12. Generalist Behavior Describes Pollen Foraging for Perceived Oligolectic and Polylectic Bees.

    Science.gov (United States)

    Ritchie, Alan D; Ruppel, Rebecca; Jha, Shalene

    2016-08-01

    Native bees provide essential pollination services to cultivated and wild plants worldwide. Despite the need to conserve pollinators, the foraging patterns of native bees are poorly understood. Classic concepts of resource use have typically categorized bee species as specialists or generalists based on floral visitation patterns. While intraspecific variation in bee foraging likely depends on local land use, sex, and phenological period, among other factors, these potential drivers of floral visitation are rarely explicitly investigated. In this study, we explore the potential for inter- and intra-specific variation in floral visitation by investigating the pollen loads of two solitary, similarly sized, ground-nesting native bee species within the Apinae, Melissodes tepaneca (Cresson) and Diadasia rinconis (Cockerell), categorized as generalist and specialist based on past floral visitation studies, respectively. Our analyses reveal generalist foraging and indicate that natural habitat availability significantly drives pollen load composition for both species. The putative specialist, D. rinconis, exhibited significant differences in pollen load composition between males and females, between pan and net collection methods, and between the different phenological periods. The putative generalist, M. tepaneca, exhibited significant differences in pollen load composition between the sexes, but only in the late season. Both species exhibited significant preference levels for multiple native plant species across the study region. Given that pollen collection is essential for native bee population persistence across natural and human-dominated habitats, our findings suggest consideration of both pollen collection and floral visitation patterns to holistically describe floral usage and develop pollinator conservation strategies.

  13. Do behavioral foraging responses of prey to predators function similarly in restored and pristine foodwebs?

    Directory of Open Access Journals (Sweden)

    Elizabeth M P Madin

    Full Text Available Efforts to restore top predators in human-altered systems raise the question of whether rebounds in predator populations are sufficient to restore pristine foodweb dynamics. Ocean ecosystems provide an ideal system to test this question. Removal of fishing in marine reserves often reverses declines in predator densities and size. However, whether this leads to restoration of key functional characteristics of foodwebs, especially prey foraging behavior, is unclear. The question of whether restored and pristine foodwebs function similarly is nonetheless critically important for management and restoration efforts. We explored this question in light of one important determinant of ecosystem function and structure--herbivorous prey foraging behavior. We compared these responses for two functionally distinct herbivorous prey fishes (the damselfish Plectroglyphidodon dickii and the parrotfish Chlorurus sordidus within pairs of coral reefs in pristine and restored ecosystems in two regions of these species' biogeographic ranges, allowing us to quantify the magnitude and temporal scale of this key ecosystem variable's recovery. We demonstrate that restoration of top predator abundances also restored prey foraging excursion behaviors to a condition closely resembling those of a pristine ecosystem. Increased understanding of behavioral aspects of ecosystem change will greatly improve our ability to predict the cascading consequences of conservation tools aimed at ecological restoration, such as marine reserves.

  14. MINERAL COMPOSITION OF SOILS, FORAGES AND ANIMAL TISSUE IN THE RIO VERDE REGION, GOIÁS, BRAZIL: IRON AND MANGANESE ESTUDO DA COMPOSIÇÃO MINERAL DE SOLOS, FORRAGENS E TECIDO ANIMAL DE BOVINOS DO MUNICÍPIO DE RIO VERDE, GOIÁS: FERRO E MANGANÊS

    Directory of Open Access Journals (Sweden)

    Eduardo Cavalheiro Jardim

    2007-09-01

    Full Text Available

    A study to determine mineral contents in cattle was conducted in three farms of Rio Verde, State of Goiás, Brazil. Soil, forage and liver samples were collected from each farm (cows and calves. Forage Mn contents were adequate for beef cattle. High levels in Fe on one farm was considered toxic for the grazing cattle. Liver levels in Fe were high in all samples.

    Foram feitas amostragens de solo, forragem e fígado (biópsia em três fazendas representativas do município de Rio Verde, Goiás, com o objetivo de determinar os níveis e possíveis deficiências de minerais na nutrição dos bovinos. Os resultados mostraram que a concentração de manganês nas forragens estão em níveis adequados para bovinos de corte. Entretanto, a concentração de ferro foi superior aos requisitos nutricionais para gado de corte.

  15. Genome-Wide Association Mapping and Genomic Selection for Alfalfa (Medicago sativa) Forage Quality Traits.

    Science.gov (United States)

    Biazzi, Elisa; Nazzicari, Nelson; Pecetti, Luciano; Brummer, E Charles; Palmonari, Alberto; Tava, Aldo; Annicchiarico, Paolo

    2017-01-01

    Genetic progress for forage quality has been poor in alfalfa (Medicago sativa L.), the most-grown forage legume worldwide. This study aimed at exploring opportunities for marker-assisted selection (MAS) and genomic selection of forage quality traits based on breeding values of parent plants. Some 154 genotypes from a broadly-based reference population were genotyped by genotyping-by-sequencing (GBS), and phenotyped for leaf-to-stem ratio, leaf and stem contents of protein, neutral detergent fiber (NDF) and acid detergent lignin (ADL), and leaf and stem NDF digestibility after 24 hours (NDFD), of their dense-planted half-sib progenies in three growing conditions (summer harvest, full irrigation; summer harvest, suspended irrigation; autumn harvest). Trait-marker analyses were performed on progeny values averaged over conditions, owing to modest germplasm × condition interaction. Genomic selection exploited 11,450 polymorphic SNP markers, whereas a subset of 8,494 M. truncatula-aligned markers were used for a genome-wide association study (GWAS). GWAS confirmed the polygenic control of quality traits and, in agreement with phenotypic correlations, indicated substantially different genetic control of a given trait in stems and leaves. It detected several SNPs in different annotated genes that were highly linked to stem protein content. Also, it identified a small genomic region on chromosome 8 with high concentration of annotated genes associated with leaf ADL, including one gene probably involved in the lignin pathway. Three genomic selection models, i.e., Ridge-regression BLUP, Bayes B and Bayesian Lasso, displayed similar prediction accuracy, whereas SVR-lin was less accurate. Accuracy values were moderate (0.3-0.4) for stem NDFD and leaf protein content, modest for leaf ADL and NDFD, and low to very low for the other traits. Along with previous results for the same germplasm set, this study indicates that GBS data can be exploited to improve both quality traits

  16. How does habitat complexity affect ant foraging success? A test using functional measures on three continents.

    Science.gov (United States)

    Gibb, H; Parr, C L

    2010-12-01

    Habitat complexity can mediate key processes that structure local assemblages through effects on factors such as competition, predation and foraging behaviour. While most studies address assemblage responses to habitat complexity within one locality, a more global approach allows conclusions with greater independence from the phylogenetic constraints of the target assemblages, thus allowing greater generality. We tested the effects of natural and manipulated habitat complexities on ant assemblages from South Africa, Australia and Sweden, in order to determine if there were globally consistent responses in how functional measures of foraging success are regulated by habitat complexity. Specifically, we considered how habitat complexity affected ant foraging rates including the speed of discovery and rate of monopolisation. We also tested if habitat complexity affected the body size index, a size-related morphological trait, of ants discovering resources and occupying and monopolising the resources after 180 min. Ants were significantly slower to discover baits in the more complex treatments, consistent with predictions that they would move more slowly through more complex environments. The monopolisation index was also lower in the more complex treatments, suggesting that resources were more difficult to defend. Our index of ant body size showed trends in the predicted direction for complexity treatments. In addition, ants discovering, occupying and monopolising resources were smaller in simple than in complex natural habitats. Responses of discovering ants to resources in natural habitats were clear in only one of three regions. Consistent with our predictions, habitat complexity thus affected functional measures of the foraging success of ants in terms of measures of discovery and monopolisation rates and body size traits of successful ants. However, patterns were not always equally clear in manipulative and mensurative components of the study.

  17. Foraging segregation and genetic divergence between geographically proximate colonies of a highly mobile seabird

    Science.gov (United States)

    Wiley, Anne E.; Welch, Andreanna J.; Ostrom, P.H.; James, Helen F.; Stricker, C.A.; Fleischer, R.C.; Gandhi, H.; Adams, J.; Ainley, D.G.; Duvall, F.; Holmes, N.; Hu, D.; Judge, S.; Penniman, J.; Swindle, K.A.

    2012-01-01

    Foraging segregation may play an important role in the maintenance of animal diversity, and is a proposed mechanism for promoting genetic divergence within seabird species. However, little information exists regarding its presence among seabird populations. We investigated genetic and foraging divergence between two colonies of endangered Hawaiian petrels (Pterodroma sandwichensis) nesting on the islands of Hawaii and Kauai using the mitochondrial Cytochrome b gene and carbon, nitrogen and hydrogen isotope values (?? 13C, ?? 15N and ??D, respectively) of feathers. Genetic analyses revealed strong differentiation between colonies on Hawaii and Kauai, with ?? ST = 0. 50 (p < 0. 0001). Coalescent-based analyses gave estimates of <1 migration event per 1,000 generations. Hatch-year birds from Kauai had significantly lower ?? 13C and ?? 15N values than those from Hawaii. This is consistent with Kauai birds provisioning chicks with prey derived from near or north of the Hawaiian Islands, and Hawaii birds provisioning young with prey from regions of the equatorial Pacific characterized by elevated ?? 15N values at the food web base. ?? 15N values of Kauai and Hawaii adults differed significantly, indicating additional foraging segregation during molt. Feather ??D varied from -69 to 53???. This variation cannot be related solely to an isotopically homogeneous ocean water source or evaporative water loss. Instead, we propose the involvement of salt gland excretion. Our data demonstrate the presence of foraging segregation between proximately nesting seabird populations, despite high species mobility. This ecological diversity may facilitate population coexistence, and its preservation should be a focus of conservation strategies. ?? 2011 Springer-Verlag (outside the USA).

  18. A model for habitat selection and species distribution derived from central place foraging theory.

    Science.gov (United States)

    Olsson, Ola; Bolin, Arvid

    2014-06-01

    We have developed a habitat selection model based on central place foraging theory. An individual's decision to include a patch in its habitat depends on the marginal fitness contribution of that patch, which is characterized by its quality and distance to the central place. The essence of the model we have developed is a fitness isocline which is a function of patch quality and travel time to the patch. It has two parameters: the maximum travel distance to a patch of infinite quality and a coefficient that appropriately scales quality by travel time. Patches falling below the isocline will have positive marginal fitness values and should be included in the habitat. The maximum travel distance depends on the availability and quality of patches, as well as on the forager's life history, whereas the scaling parameter mostly depends on life history properties. Using the model, we derived a landscape quality metric (which can be thought of as a connectivity measure) that sums the values of available habitat in the landscape around a central place. We then fitted the two parameters to foraging data on breeding white storks (Ciconia ciconia) and estimated landscape quality, which correlated strongly with reproductive success. Landscape quality was then calculated for a larger region where re-introduction of the species is currently going on in order to demonstrate how this model can also be regarded as a species distribution model. In conclusion, we have built a general habitat selection model for central place foragers and a novel way of estimating landscape quality based on a behaviorally scaled connectivity metric.

  19. Avian foods, foraging and habitat conservation in world rice fields

    Science.gov (United States)

    Stafford, J.D.; Kaminski, R.M.; Reinecke, K.J.

    2010-01-01

    Worldwide, rice (Oryza sativa) agriculture typically involves seasonal flooding and soil tillage, which provides a variety of microhabitats and potential food for birds. Water management in rice fields creates conditions ranging from saturated mud flats to shallow (seed mass from North America ranging from 66672 kg/ha. Although initially abundant after harvest, waste rice availability can be temporally limited. Few abundance estimates for other foods, such as vertebrate prey or forage vegetation, exist for rice fields. Outside North America, Europe and Japan, little is known about abundance and importance of any avian food in rice fields. Currently, flooding rice fields after harvest is the best known management practice to attract and benefit birds. Studies from North America indicate specific agricultural practices (e.g. burning stubble) may increase use and improve access to food resources. Evaluating and implementing management practices that are ecologically sustainable, increase food for birds and are agronomically beneficial should be global priorities to integrate rice production and avian conservation. Finally, land area devoted to rice agriculture appears to be stable in the USA, declining in China, and largely unquantified in many regions. Monitoring trends in riceland area may provide information to guide avian conservation planning in rice-agriculture ecosystems.

  20. Adelie penguin foraging location predicted by tidal regime switching.

    Directory of Open Access Journals (Sweden)

    Matthew J Oliver

    Full Text Available Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

  1. Traffic noise reduces foraging efficiency in wild owls

    Science.gov (United States)

    Senzaki, Masayuki; Yamaura, Yuichi; Francis, Clinton D.; Nakamura, Futoshi

    2016-08-01

    Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise.

  2. Forage maize nutritional quality according to organic and inorganic fertilization

    National Research Council Canada - National Science Library

    Alejandro Moreno-Reséndez; Jesús Enrique Cantú Brito; José Luis Reyes-Carrillo; Viridiana Contreras-Villarreal

    2017-01-01

    ... to establish the effect of two fertilization sources – organic and inorganic, upon the nutritional quality of forage maize during the spring - summer cycle with a r andomized block experimental design. T 1 = Acadian soil +Acadian foliage...

  3. (AJST) FORAGE POTENTIAL, MICRO-SPATIAL AND TEMPORAL ...

    African Journals Online (AJOL)

    NORBERT OPIYO AKECH

    wetlands persists. An investigation into the abundance, distribution and forage potential of ground ... wetlands persists. Waterbird population declines in coastal ... ecological status resulting from human use, climate change and pollution.

  4. Evaluation of nutritional value some forage species available in Iran ...

    African Journals Online (AJOL)

    Novin

    2012-07-17

    Jul 17, 2012 ... between gas production parameters and CP content of forage species. The study shows that these ..... Legume, grass and legume-grass mixture quality standards. Quality standard1 ..... Temperature effects on anatomy and ...

  5. Session B6 Management for sustainable use — Forage production ...

    African Journals Online (AJOL)

    The integration of herbaceous and/or woody forage to supplement natural range ... The relative effects of dry and wet season grazing are closely examined for a ... communal grazing, grazing selection and extension/development are other ...

  6. Testing forage legume technologies with smallholder dairy farmers ...

    African Journals Online (AJOL)

    Mo

    the application of improved forage and feed technologies. This paper presents .... It was at this time of the year when maize/lablab stover was harvested. ..... World Bank through the Agricultural Research and Training. Programme (ARTP) ...

  7. Alfalfa (Medicago Sativa L As A Promising Forage In Indonesia

    Directory of Open Access Journals (Sweden)

    Sajimin

    2011-06-01

    Full Text Available Alfalfa (Medicago sativa L or Lucerne is a perennial herbaceous legume with superior forage quality. It is the most important forage crop in the world and it was the first domesticated forage crop. Alfalfa is able to fix nitrogen from the air through a symbiotic relationship with Rhizobium bacteria with N production 7.85 – 10.37 g/m2. Its rooting system can reach 4.5 m that allows it to escape drought. Forage production can reach 15.48 tons of dry matter per ha/year and containing 18.0 – 29.1 % crude protein. Plants can live 3 to 12 years depending on climatic conditions and crop varieties. However, alfalfa is not a tropical plant, thus it has not been widely cultivated in Indonesia. The problem of alfalfa cultivation are high pest attacks and competition with weeds. Therefore, alfalfa cultivation requires attention and good management to obtain optimum yield.

  8. Ecological factors affecting the foraging behaviour of Xerus rutilus ...

    African Journals Online (AJOL)

    The African unstriped ground squirrel (Xerus rutilus) is widely dispersed across ... efficiency to explore the foraging costs of environmental heterogeneity. ... with common plant toxins, we presented the squirrels with seeds soaked in either ...

  9. Forage fish, their fisheries, and their predators: who drives whom?

    DEFF Research Database (Denmark)

    Engelhard, Georg H.; Peck, Myron A.; Rindorf, Anna;

    2014-01-01

    The North Sea has a diverse forage fish assemblage, including herring, targeted for human consumption; sandeel, sprat, and Norway pout, exploited by industrial fisheries; and some sardine and anchovy, supporting small-scale fisheries. All show large abundance fluctuations, impacting on fisheries...... exist, as in the North Sea. Sandeel appears to be the most important prey forage fish. Seabirds are most dependent on forage fish, due to specialized diet and distributional constraints (breeding colonies). Other than fisheries, key predators of forage fish are a few piscivorous fish species including...... saithe, whiting, mackerel, and horse-mackerel, exploited in turn by fisheries; seabirds and seals have a more modest impact. Size-based foodwebmodelling suggests that reducing fishing mortality may not necessarily lead to larger stocks of piscivorous fish, especially if their early life stages compete...

  10. Simple cellular automata to mimic foraging ants submitted to abduction

    CERN Document Server

    Tejera, F

    2015-01-01

    Many species of ants forage by building up two files: an outbound one moving from the nest to the foraging area, and a nestbound one, returning from it to the nest. Those files are eventually submitted to different threats. If the danger is concentrated at one point of the file, one might expect that ants returning to the nest will pass danger information to their nestmates moving in the opposite direction towards the danger area. In this paper, we construct simple cellular automata models for foraging ants submitted to localized abduction, were danger information is transmitted using different protocols, including the possibility of no transmission. The parameters we have used in the simulations have been estimated from actual experiments under natural conditions. So, it would be easy to test our information-transmission hypothese in real experiments. Preliminary experimental results published elsewhere suggest that the behavior of foraging ants of the species Atta insularis is best described using the hypot...

  11. Oxidative phenols in forage crops containing polyphenol oxidase enzymes.

    Science.gov (United States)

    Parveen, Ifat; Threadgill, Michael D; Moorby, Jon M; Winters, Ana

    2010-02-10

    Polyphenol oxidases (PPOs) are copper-containing enzymes that catalyze oxidation of endogenous monophenols to ortho-dihydroxyaryl compounds and of ortho-dihydroxyaryl compounds to ortho-quinones. Subsequent nucleophilic addition reactions of phenols, amino acids, and proteins with the electrophilic ortho-quinones form brown-, black-, or red-colored secondary products associated with the undesired discolouration of fruit and vegetables. Several important forage plants also exhibit significant PPO activity, and a link with improved efficiency of ruminant production has been established. In ruminant animals, extensive degradation of forage proteins, following consumption, can result in high rates of excretion of nitrogen, which contributes to point-source and diffuse pollution. Reaction of quinones with forage proteins leads to the formation of protein-phenol complexes that are resistant to proteolytic activity during ensilage and during rumen fermentation. Thus, PPO in red clover (Trifolium pratense) has been shown to improve protein utilization by ruminants. While PPO activity has been demonstrated in a number of forage crops, little work has been carried out to identify substrates of PPO, knowledge of which would be beneficial for characterizing this trait in these forages. In general, a wide range of 1,2-dihydroxyarenes can serve as PPO substrates because these are readily oxidized because of the ortho positioning of the hydroxy groups. Naturally occurring phenols isolated from forage crops with PPO activity are reviewed. A large number of phenols, which may be directly or indirectly oxidized as a consequence of PPO activity, have been identified in several forage grass, legume, cereal, and brassica species; these include hydroxybenzoic acids, hydroxycinnamates, and flavonoids. In conclusion, a number of compounds are known or postulated to enable PPO activity in important PPO-expressing forage crops. Targeting the matching of these compounds with PPO activity

  12. The forager oral tradition and the evolution of prolonged juvenility

    Directory of Open Access Journals (Sweden)

    Michelle Scalise Sugiyama

    2011-08-01

    Full Text Available The foraging niche is characterized by the exploitation of nutrient-rich resources using complex extraction techniques that take a long time to acquire. This costly period of development is supported by intensive parental investment. Although human life history theory tends to characterize this investment in terms of food and care, ethnographic research on foraging skill transmission suggests that the flow of resources from old to young also includes knowledge. Given the adaptive value of information, parents may have been under selection pressure to invest knowledge—e.g., warnings, advice--in children: proactive provisioning of reliable information would have increased offspring survival rates and, hence, parental fitness. One way that foragers acquire subsistence knowledge is through symbolic communication, including narrative. Tellingly, oral traditions are characterized by an old-to-young transmission pattern, which suggests that, in forager groups, storytelling might be an important means by which adults transfer knowledge to juveniles. In particular, by providing juveniles with vicarious experience, storytelling may expand episodic memory, which is believed to be integral to the generation of possible future scenarios (i.e., planning. In support of this hypothesis, this essay reviews evidence that: mastery of foraging knowledge and skill sets takes a long time to acquire; foraging knowledge is transmitted from parent to child; the human mind contains adaptations specific to social learning; full assembly of learning mechanisms is not complete in early childhood; and forager oral traditions contain a wide range of information integral to occupation of the foraging niche. It concludes with suggestions for tests of the proposed hypothesis.

  13. Food availability and foraging near human developments by black bears

    Science.gov (United States)

    Merkle, Jerod A.; Robinson, Hugh S.; Krausman, Paul R.; Alaback, Paul B.

    2013-01-01

    Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed <10%. Black bears foraged on human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

  14. Flexible Foraging of Ants under Unsteadily Varying Environment

    Science.gov (United States)

    Tao, Tomomi; Nakagawa, Hiroyuki; Yamasaki, Masato; Nishimori, Hiraku

    2004-08-01

    Using a simple model for the trail formation of ants, the relation between i) the schedule of feeding which represents the unsteady natural environment, ii) emerging patterns of trails connecting a nest with food resources, and iii) the foraging efficiency is studied. Simulations and a simple analysis show that the emergent trail pattern flexibly varies depending on the feeding schedule by which ants can make an efficient foraging according to the underlying unsteady environment.

  15. On methodology of foraging behavior of pollinating insects

    OpenAIRE

    Yanbing Gong; Shuangquan Huang

    2007-01-01

    Foraging behavior of pollinating insects can directly influence plant–pollinator interactions in many aspects, thus studies on pollinator behavior are important for understanding plant diversity and ecological processes of plant reproduction. In this paper, we describe the characteristics of major pollinating insects and discuss the methods for studying foraging behavior of pollinating insects and factors potentially influencing pollinator behaviors. We also suggest some practical methods for...

  16. Foraging decisions, patch use, and seasonality in egrets (Aves: ciconiiformes)

    Science.gov (United States)

    Erwin, R.M.

    1985-01-01

    Feeding snowy (Egretta thula) and great (Casmerodius albus) egrets were observed during 2 breeding seasons in coastal New Jersey and 2 brief winter periods in northeast Florida (USA). A number of tests based on assumptions of foraging models, predictions from foraging theory, and earlier empirical tests concerning time allocation and movement in foraging patches was made. Few of the expectations based on foraging theory and/or assumptions were supported by the empirical evidence. Snowy egrets fed with greater intensity and efficiency during the breeding season (when young were being fed) than during winter. They also showed some tendency to leave patches when their capture rate declined, and they spent more time foraging in patches when other birds were present nearby. Great egrets showed few of these tendencies, although they did leave patches when their intercapture intervals increased. Satiation differences had some influence on feeding rates in snowy egrets, but only at the end of feeding bouts. Some individuals of both species revisited areas in patches that had recently been exploited, and success rates were usually higher after the 2nd visit. Apparently, for predators of active prey, short-term changes in resource availability ('resource depression') may be more important than resource depletion, a common assumption in most optimal foraging theory models.

  17. Evidence for ship noise impacts on humpback whale foraging behaviour.

    Science.gov (United States)

    Blair, Hannah B; Merchant, Nathan D; Friedlaender, Ari S; Wiley, David N; Parks, Susan E

    2016-08-01

    Noise from shipping activity in North Atlantic coastal waters has been steadily increasing and is an area of growing conservation concern, as it has the potential to disrupt the behaviour of marine organisms. This study examines the impacts of ship noise on bottom foraging humpback whales (Megaptera novaeangliae) in the western North Atlantic. Data were collected from 10 foraging whales using non-invasive archival tags that simultaneously recorded underwater movements and the acoustic environment at the whale. Using mixed models, we assess the effects of ship noise on seven parameters of their feeding behaviours. Independent variables included the presence or absence of ship noise and the received level of ship noise at the whale. We found significant effects on foraging, including slower descent rates and fewer side-roll feeding events per dive with increasing ship noise. During 5 of 18 ship passages, dives without side-rolls were observed. These findings indicate that humpback whales on Stellwagen Bank, an area with chronically elevated levels of shipping traffic, significantly change foraging activity when exposed to high levels of ship noise. This measureable reduction in within-dive foraging effort of individual whales could potentially lead to population-level impacts of shipping noise on baleen whale foraging success.

  18. Information Foraging in Nuclear Power Plant Control Rooms

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Boring

    2011-09-01

    nformation foraging theory articulates the role of the human as an 'informavore' that seeks information and follows optimal foraging strategies (i.e., the 'information scent') to find meaningful information. This paper briefly reviews the findings from information foraging theory outside the nuclear domain and then discusses the types of information foraging strategies operators employ for normal and off-normal operations in the control room. For example, operators may employ a predatory 'wolf' strategy of hunting for information in the face of a plant upset. However, during routine operations, the operators may employ a trapping 'spider' strategy of waiting for relevant indicators to appear. This delineation corresponds to information pull and push strategies, respectively. No studies have been conducted to determine explicitly the characteristics of a control room interface that is optimized for both push and pull information foraging strategies, nor has there been empirical work to validate operator performance when transitioning between push and pull strategies. This paper explores examples of control room operators as wolves vs. spiders and con- cludes by proposing a set of research questions to investigate information foraging in control room settings.

  19. Chaos-order transition in foraging behavior of ants.

    Science.gov (United States)

    Li, Lixiang; Peng, Haipeng; Kurths, Jürgen; Yang, Yixian; Schellnhuber, Hans Joachim

    2014-06-10

    The study of the foraging behavior of group animals (especially ants) is of practical ecological importance, but it also contributes to the development of widely applicable optimization problem-solving techniques. Biologists have discovered that single ants exhibit low-dimensional deterministic-chaotic activities. However, the influences of the nest, ants' physical abilities, and ants' knowledge (or experience) on foraging behavior have received relatively little attention in studies of the collective behavior of ants. This paper provides new insights into basic mechanisms of effective foraging for social insects or group animals that have a home. We propose that the whole foraging process of ants is controlled by three successive strategies: hunting, homing, and path building. A mathematical model is developed to study this complex scheme. We show that the transition from chaotic to periodic regimes observed in our model results from an optimization scheme for group animals with a home. According to our investigation, the behavior of such insects is not represented by random but rather deterministic walks (as generated by deterministic dynamical systems, e.g., by maps) in a random environment: the animals use their intelligence and experience to guide them. The more knowledge an ant has, the higher its foraging efficiency is. When young insects join the collective to forage with old and middle-aged ants, it benefits the whole colony in the long run. The resulting strategy can even be optimal.

  20. Chaos–order transition in foraging behavior of ants

    Science.gov (United States)

    Li, Lixiang; Peng, Haipeng; Kurths, Jürgen; Yang, Yixian; Schellnhuber, Hans Joachim

    2014-01-01

    The study of the foraging behavior of group animals (especially ants) is of practical ecological importance, but it also contributes to the development of widely applicable optimization problem-solving techniques. Biologists have discovered that single ants exhibit low-dimensional deterministic-chaotic activities. However, the influences of the nest, ants’ physical abilities, and ants’ knowledge (or experience) on foraging behavior have received relatively little attention in studies of the collective behavior of ants. This paper provides new insights into basic mechanisms of effective foraging for social insects or group animals that have a home. We propose that the whole foraging process of ants is controlled by three successive strategies: hunting, homing, and path building. A mathematical model is developed to study this complex scheme. We show that the transition from chaotic to periodic regimes observed in our model results from an optimization scheme for group animals with a home. According to our investigation, the behavior of such insects is not represented by random but rather deterministic walks (as generated by deterministic dynamical systems, e.g., by maps) in a random environment: the animals use their intelligence and experience to guide them. The more knowledge an ant has, the higher its foraging efficiency is. When young insects join the collective to forage with old and middle-aged ants, it benefits the whole colony in the long run. The resulting strategy can even be optimal. PMID:24912159

  1. Variability in individual activity bursts improves ant foraging success.

    Science.gov (United States)

    Campos, Daniel; Bartumeus, Frederic; Méndez, Vicenç; Andrade, José S; Espadaler, Xavier

    2016-12-01

    Using experimental and computational methods, we study the role of behavioural variability in activity bursts (or temporal activity patterns) for individual and collective regulation of foraging in A. senilis ants. First, foraging experiments were carried out under special conditions (low densities of ants and food and absence of external cues or stimuli) where individual-based strategies are most prevalent. By using marked individuals and recording all foraging trajectories, we were then able to precisely quantify behavioural variability among individuals. Our main conclusions are that (i) variability of ant trajectories (turning angles, speed, etc.) is low compared with variability of temporal activity profiles, and (ii) this variability seems to be driven by plasticity of individual behaviour through time, rather than the presence of fixed behavioural stereotypes or specialists within the group. The statistical measures obtained from these experimental foraging patterns are then used to build a general agent-based model (ABM) which includes the most relevant properties of ant foraging under natural conditions, including recruitment through pheromone communication. Using the ABM, we are able to provide computational evidence that the characteristics of individual variability observed in our experiments can provide a functional advantage (in terms of foraging success) to the group; thus, we propose the biological basis underpinning our observations. Altogether, our study reveals the potential utility of experiments under simplified (laboratory) conditions for understanding information-gathering in biological systems. © 2016 The Author(s).

  2. Cotton Rats Alter Foraging in Response to an Invasive Ant.

    Science.gov (United States)

    Darracq, Andrea K; Conner, L Mike; Brown, Joel S; McCleery, Robert A

    We assessed the effects of red imported fire ants (Solenopsis invicta; hereafter fire ant) on the foraging of hispid cotton rats (Sigmodon hispidus). We used a manipulative experiment, placing resource patches with a known amount of millet seed within areas with reduced (RIFA [-]) or ambient (RIFA [+]) numbers of fire ants. We measured giving up densities (the amount of food left within each patch) within the resource patches for 4 days to quantify the effects of fire ants on cotton rat foraging. We assessed the effects of fire ant treatment (RIFA), Day, and their interaction on cotton rat giving up densities. Giving up densities on RIFA [+] grids were nearly 2.2 times greater across all foraging days and ranged from 1.6 to 2.3 times greater from day 1 to day 4 than the RIFA [-] grids. From day 1 to day 4, mean giving up densities decreased significantly faster for the RIFA [-] than RIFA [+] treatments, 58% and 13%, respectively. Our results demonstrate that cotton rats perceive a risk of injury from fire ants, which is likely caused by interference competition, rather than direct predation. Envenomation from ants likely decrease the foraging efficiency of cotton rats resulting in more time spent foraging. Increased time spent foraging is likely stressful in terms of the opportunity for direct injury and encounters with other predators. These indirect effects may reduce an individual cotton rat's fitness and translate into lowered population abundances.

  3. Diurnal Leaf Starch Content: An Orphan Trait in Forage Legumes

    Directory of Open Access Journals (Sweden)

    Michael E. Ruckle

    2017-02-01

    Full Text Available Forage legumes have a relatively high biomass yield and crude protein content, but their grazed and harvested biomass lacks the high-energy carbohydrates required to meet the productivity potential of modern livestock breeds. Because of their low carbohydrate content, forage legume diets are typically supplemented with starch rich cereal grains or maize (Zea mays, leading to the disruption of local nutrient cycles. Although plant leaves were first reported to accumulate starch in a diurnal pattern over a century ago, leaf starch content has yet to be exploited as an agronomic trait in forage crops. Forage legumes such as red clover (Trifolium pratense have the genetic potential to accumulate up to one third of their leaf dry mass as starch, but this starch is typically degraded at night to support nighttime growth and respiration. Even when diurnal accumulation is considered with regard to the time the crop is harvested, only limited gains are realized due to environmental effects and post-harvest losses from respiration. Here we present original data for starch metabolism in red clover and place it in the broader context of other forage legumes such as, white clover (T. repens, and alfalfa (Medicago sativa. We review the application of recent advances in molecular breeding, plant biology, and crop phenotyping, to forage legumes to improve and exploit a potentially valuable trait for sustainable ruminant livestock production.

  4. Waggle Dance Distances as Integrative Indicators of Seasonal Foraging Challenges

    Science.gov (United States)

    Couvillon, Margaret J.; Schürch, Roger; Ratnieks, Francis L. W.

    2014-01-01

    Even as demand for their services increases, honey bees (Apis mellifera) and other pollinating insects continue to decline in Europe and North America. Honey bees face many challenges, including an issue generally affecting wildlife: landscape changes have reduced flower-rich areas. One way to help is therefore to supplement with flowers, but when would this be most beneficial? We use the waggle dance, a unique behaviour in which a successful forager communicates to nestmates the location of visited flowers, to make a 2-year survey of food availability. We “eavesdropped” on 5097 dances to track seasonal changes in foraging, as indicated by the distance to which the bees as economic foragers will recruit, over a representative rural-urban landscape. In year 3, we determined nectar sugar concentration. We found that mean foraging distance/area significantly increase from springs (493 m, 0.8 km2) to summers (2156 m, 15.2 km2), even though nectar is not better quality, before decreasing in autumns (1275 m, 5.1 km2). As bees will not forage at long distances unnecessarily, this suggests summer is the most challenging season, with bees utilizing an area 22 and 6 times greater than spring or autumn. Our study demonstrates that dancing bees as indicators can provide information relevant to helping them, and, in particular, can show the months when additional forage would be most valuable. PMID:24695678

  5. Nutritional Characteristics of Forage Grown in South of Benin

    Directory of Open Access Journals (Sweden)

    Nadia Musco

    2016-01-01

    Full Text Available In order to provide recommendations on the most useful forage species to smallholder farmers, eleven grass and eleven legume forages grown in Abomey-Calavi in Republic of Benin were investigated for nutritive value (i.e. chemical composition and energy content and fermentation characteristics (i.e. gas and volatile fatty acid production, organic matter degradability. The in vitro gas production technique was used, incubating the forages for 120 h under anaerobic condition with buffalo rumen fluid. Compared to legume, tropical grass forages showed lower energy (8.07 vs 10.57 MJ/kg dry matter [DM] and crude protein level (16.10% vs 19.91% DM and higher cell wall content (neutral detergent fiber: 63.8% vs 40.45% DM, respectively. In grass forages, the chemical composition showed a quite high crude protein content; the in vitro degradability was slightly lower than the range of tropical pasture. The woody legumes were richer in protein and energy and lower in structural carbohydrates than herbaceous plants, however, their in vitro results are influenced by the presence of complex compounds (i.e. tannins. Significant correlations were found between chemical composition and in vitro fermentation characteristics. The in vitro gas production method appears to be a suitable technique for the evaluation of the nutritive value of forages in developing countries.

  6. Tandem carrying, a new foraging strategy in ants: description, function, and adaptive significance relative to other described foraging strategies

    Science.gov (United States)

    Guénard, Benoit; Silverman, Jules

    2011-08-01

    An important aspect of social insect biology lies in the expression of collective foraging strategies developed to exploit food. In ants, four main types of foraging strategies are typically recognized based on the intensity of recruitment and the importance of chemical communication. Here, we describe a new type of foraging strategy, "tandem carrying", which is also one of the most simple recruitment strategies, observed in the Ponerinae species Pachycondyla chinensis. Within this strategy, workers are directly carried individually and then released on the food resource by a successful scout. We demonstrate that this recruitment is context dependent and based on the type of food discovered and can be quickly adjusted as food quality changes. We did not detect trail marking by tandem-carrying workers. We conclude by discussing the importance of tandem carrying in an evolutionary context relative to other modes of recruitment in foraging and nest emigration.

  7. Ant Foraging Behavior for Job Shop Problem

    Directory of Open Access Journals (Sweden)

    Mahad Diyana Abdul

    2016-01-01

    Full Text Available Ant Colony Optimization (ACO is a new algorithm approach, inspired by the foraging behavior of real ants. It has frequently been applied to many optimization problems and one such problem is in solving the job shop problem (JSP. The JSP is a finite set of jobs processed on a finite set of machine where once a job initiates processing on a given machine, it must complete processing and uninterrupted. In solving the Job Shop Scheduling problem, the process is measure by the amount of time required in completing a job known as a makespan and minimizing the makespan is the main objective of this study. In this paper, we developed an ACO algorithm to minimize the makespan. A real set of problems from a metal company in Johor bahru, producing 20 parts with jobs involving the process of clinching, tapping and power press respectively. The result from this study shows that the proposed ACO heuristics managed to produce a god result in a short time.

  8. Ocean acidification impairs crab foraging behaviour.

    Science.gov (United States)

    Dodd, Luke F; Grabowski, Jonathan H; Piehler, Michael F; Westfield, Isaac; Ries, Justin B

    2015-07-07

    Anthropogenic elevation of atmospheric CO2 is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism's ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO2 levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Leaf Length Variation in Perennial Forage Grasses

    Directory of Open Access Journals (Sweden)

    Philippe Barre

    2015-08-01

    Full Text Available Leaf length is a key factor in the economic value of different grass species and cultivars in forage production. It is also important for the survival of individual plants within a sward. The objective of this paper is to discuss the basis of within-species variation in leaf length. Selection for leaf length has been highly efficient, with moderate to high narrow sense heritability. Nevertheless, the genetic regulation of leaf length is complex because it involves many genes with small individual effects. This could explain the low stability of QTL found in different studies. Leaf length has a strong response to environmental conditions. However, when significant genotype × environment interactions have been identified, their effects have been smaller than the main effects. Recent modelling-based research suggests that many of the reported environmental effects on leaf length and genotype × environment interactions could be biased. Indeed, it has been shown that leaf length is an emergent property strongly affected by the architectural state of the plant during significant periods prior to leaf emergence. This approach could lead to improved understanding of the factors affecting leaf length, as well as better estimates of the main genetic effects.

  10. Color and polarization vision in foraging Papilio.

    Science.gov (United States)

    Kinoshita, Michiyo; Arikawa, Kentaro

    2014-06-01

    This paper gives an overview of behavioral studies on the color and polarization vision of the Japanese yellow swallowtail butterfly, Papilio xuthus. We focus on indoor experiments on foraging individuals. Butterflies trained to visit a disk of certain color correctly select that color among various other colors and/or shades of gray. Correct selection persists under colored illumination, but is systematically shifted by background colors, indicating color constancy and simultaneous color contrast. While their eyes contain six classes of spectral receptors, their wavelength discrimination performance indicates that their color vision is tetrachromatic. P. xuthus innately prefers brighter targets, but can be trained to select dimmer ones under certain conditions. Butterflies trained to a dark red stimulus select an orange disk presented on a bright gray background over one on dark gray. The former probably appears darker to them, indicating brightness contrast. P. xuthus has a strong innate preference for vertically polarized light, but the selection of polarized light changes depending on the intensity of simultaneously presented unpolarized light. Discrimination of polarization also depends on background intensity. Similarities between brightness and polarization vision suggest that P. xuthus perceive polarization angle as brightness, such that vertical polarization appears brighter than horizontal polarization.

  11. Simultaneous brightness contrast of foraging Papilio butterflies.

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-05-22

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast.

  12. Effect of Citrus floral extracts on the foraging behavior of the stingless bee Scaptotrigona pectoralis (Dalla Torre

    Directory of Open Access Journals (Sweden)

    Julieta Grajales-Conesa

    2012-03-01

    Full Text Available Effect of Citrus floral extracts on the foraging behavior of the stingless bee Scaptotrigona pectoralis (Dalla Torre. Stingless bees have an important role as pollinators of many wild and cultivated plant species in tropical regions. Little is known, however, about the interaction between floral fragrances and the foraging behavior of meliponine species. Thus we investigated the chemical composition of the extracts of citric (lemon and orange flowers and their effects on the foraging behavior of the stingless bee Scaptotrigona pectoralis. We found that each type of flower has its own specific blend of major compounds: limonene (62.9% for lemon flowers, and farnesol (26.5%, (E-nerolidol (20.8%, and linalool (12.7% for orange flowers. In the foraging experiments the S. pectoralis workers were able to use the flower extracts to orient to the food source, overlooking plates baited with hexane only. However, orange flower extracts were seemingly more attractive to these worker bees, maybe because of the particular blend present in it. Our results reveal that these fragrances are very attractive to S. pectoralis, so we can infer that within citric orchards they could be important visitors in the study area; however habitat destruction, overuse of pesticides and the competitive override by managed honeybees might have put at risk their populations and thus the ecological services they provide to us.

  13. Clark's Nutcracker Breeding Season Space Use and Foraging Behavior.

    Directory of Open Access Journals (Sweden)

    Taza D Schaming

    Full Text Available Considering the entire life history of a species is fundamental to developing effective conservation strategies. Decreasing populations of five-needle white pines may be leading to the decline of Clark's nutcrackers (Nucifraga columbiana. These birds are important seed dispersers for at least ten conifer species in the western U.S., including whitebark pine (Pinus albicaulis, an obligate mutualist of Clark's nutcrackers. For effective conservation of both Clark's nutcrackers and whitebark pine, it is essential to ensure stability of Clark's nutcracker populations. My objectives were to examine Clark's nutcracker breeding season home range size, territoriality, habitat selection, and foraging behavior in the southern Greater Yellowstone Ecosystem, a region where whitebark pine is declining. I radio-tracked Clark's nutcrackers in 2011, a population-wide nonbreeding year following a low whitebark pine cone crop, and 2012, a breeding year following a high cone crop. Results suggest Douglas-fir (Pseudotsuga menziesii communities are important habitat for Clark's nutcrackers because they selected it for home ranges. In contrast, they did not select whitebark pine habitat. However, Clark's nutcrackers did adjust their use of whitebark pine habitat between years, suggesting that, in some springs, whitebark pine habitat may be used more than previously expected. Newly extracted Douglas-fir seeds were an important food source both years. On the other hand, cached seeds made up a relatively lower proportion of the diet in 2011, suggesting cached seeds are not a reliable spring food source. Land managers focus on restoring whitebark pine habitat with the assumption that Clark's nutcrackers will be available to continue seed dispersal. In the Greater Yellowstone Ecosystem, Clark's nutcracker populations may be more likely to be retained year-round when whitebark pine restoration efforts are located adjacent to Douglas-fir habitat. By extrapolation, whitebark

  14. Root Foraging Performance and Life-History Traits.

    Science.gov (United States)

    Weiser, Martin; Koubek, Tomáš; Herben, Tomáš

    2016-01-01

    Plants use their roots to forage for nutrients in heterogeneous soil environments, but different plant species vastly differ in the intensity of foraging they perform. This diversity suggests the existence of constraints on foraging at the species level. We therefore examined the relationships between the intensity of root foraging and plant body traits across species in order to estimate the degree of coordination between plant body traits and root foraging as a form of plant behavior. We cultivated 37 perennial herbaceous Central European species from open terrestrial habitats in pots with three different spatial gradients of nutrient availability (steep, shallow, and no gradient). We assessed the intensity of foraging as differences in root placement inside pots with and without a spatial gradient of resource supply. For the same set of species, we retrieved data about body traits from available databases: maximum height at maturity, mean area of leaf, specific leaf area, shoot lifespan, ability to self-propagate clonally, maximal lateral spread (in clonal plants only), realized vegetative growth in cultivation, and realized seed regeneration in cultivation. Clonal plants and plants with extensive vegetative growth showed considerably weaker foraging than their non-clonal or slow-growing counterparts. There was no phylogenetic signal in the amount of expressed root foraging intensity. Since clonal plants foraged less than non-clonals and foraging intensity did not seem to be correlated with species phylogeny, we hypothesize that clonal growth itself (i.e., the ability to develop at least partly self-sustaining ramets) may be an answer to soil heterogeneity. Whereas unitary plants use roots as organs specialized for both resource acquisition and transport to overcome spatial heterogeneity in resource supply, clonal plants separate these two functions. Becoming a clonal plant allows higher specialization at the organ level, since a typical clonal plant can be

  15. Intensive rainfed and irrigated forage crop production for Mediterranean Italian Buffalo feeding

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    N. Berardo

    2010-02-01

    Full Text Available Buffalo intensive husbandry represents the most lucrative dairy activity in Campania Region. The main forage crop system used in this area are based on winter Italian reygrass (Lolium multiflorum Lam. and spring corn (Zea mays L.. The continuous growing of this crops stressed the soil with a consequent reduction of yield potential. The experiment aimed to assess the agronomic and nutritive feeding value of Italian ryegrasscorn vs other cropping systems (models based on double rotated legumes and graminaceous crops grown under irrigated and rainfed water supply.

  16. Effects of PEG-induced osmotic stress on growth and dhurrin levels of forage sorghum

    DEFF Research Database (Denmark)

    O'Donnell, Natalie H.; Møller, Birger Lindberg; Neale, Alan D.

    2013-01-01

    Sorghum (Sorghum bicolor L. Moench) is a valuable forage crop in regions with low soil moisture. Sorghum may accumulate high concentrations of the cyanogenic glucoside dhurrin when drought stressed resulting in possible cyanide (HCN) intoxication of grazing animals. In addition, high concentrations....... Given that finely regulating soil moisture under controlled conditions is notoriously difficult, we exposed sorghum plants to varying degrees of osmotic stress by growing them for different lengths of time in hydroponic solutions containing polyethylene glycol (PEG). Plants grown in medium containing 20...

  17. Harvester ant colony variation in foraging activity and response to humidity.

    Science.gov (United States)

    Gordon, Deborah M; Dektar, Katherine N; Pinter-Wollman, Noa

    2013-01-01

    Collective behavior is produced by interactions among individuals. Differences among groups in individual response to interactions can lead to ecologically important variation among groups in collective behavior. Here we examine variation among colonies in the foraging behavior of the harvester ant, Pogonomyrmex barbatus. Previous work shows how colonies regulate foraging in response to food availability and desiccation costs: the rate at which outgoing foragers leave the nest depends on the rate at which foragers return with food. To examine how colonies vary in response to humidity and in foraging rate, we performed field experiments that manipulated forager return rate in 94 trials with 17 colonies over 3 years. We found that the effect of returning foragers on the rate of outgoing foragers increases with humidity. There are consistent differences among colonies in foraging activity that persist from year to year.

  18. Harvester ant colony variation in foraging activity and response to humidity.

    Directory of Open Access Journals (Sweden)

    Deborah M Gordon

    Full Text Available Collective behavior is produced by interactions among individuals. Differences among groups in individual response to interactions can lead to ecologically important variation among groups in collective behavior. Here we examine variation among colonies in the foraging behavior of the harvester ant, Pogonomyrmex barbatus. Previous work shows how colonies regulate foraging in response to food availability and desiccation costs: the rate at which outgoing foragers leave the nest depends on the rate at which foragers return with food. To examine how colonies vary in response to humidity and in foraging rate, we performed field experiments that manipulated forager return rate in 94 trials with 17 colonies over 3 years. We found that the effect of returning foragers on the rate of outgoing foragers increases with humidity. There are consistent differences among colonies in foraging activity that persist from year to year.

  19. Sublethal imidacloprid effects on honey bee flower choices when foraging.

    Science.gov (United States)

    Karahan, Ahmed; Çakmak, Ibrahim; Hranitz, John M; Karaca, Ismail; Wells, Harrington

    2015-11-01

    Neonicotinoids, systemic neuro-active pesticides similar to nicotine, are widely used in agriculture and are being investigated for a role in honey bee colony losses. We examined one neonicotinoid pesticide, imidacloprid, for its effects on the foraging behavior of free-flying honey bees (Apis mellifera anatoliaca) visiting artificial blue and white flowers. Imidacloprid doses, ranging from 1/5 to 1/50 of the reported LD50, were fed to bees orally. The study consisted of three experimental parts performed sequentially without interruption. In Part 1, both flower colors contained a 4 μL 1 M sucrose solution reward. Part 2 offered bees 4 μL of 1.5 M sucrose solution in blue flowers and a 4 μL 0.5 M sucrose solution reward in white flowers. In Part 3 we reversed the sugar solution rewards, while keeping the flower color consistent. Each experiment began 30 min after administration of the pesticide. We recorded the percentage of experimental bees that returned to forage after treatment. We also recorded the visitation rate, number of flowers visited, and floral reward choices of the bees that foraged after treatment. The forager return rate declined linearly with increasing imidacloprid dose. The number of foraging trips by returning bees was also affected adversely. However, flower fidelity was not affected by imidacloprid dose. Foragers visited both blue and white flowers extensively in Part 1, and showed greater fidelity for the flower color offering the higher sugar solution reward in Parts 2 and 3. Although larger samples sizes are needed, our study suggests that imidacloprid may not affect the ability to select the higher nectar reward when rewards were reversed. We observed acute, mild effects on foraging by honey bees, so mild that storage of imidacloprid tainted-honey is very plausible and likely to be found in honey bee colonies.

  20. Insect prey foraging strategies in Callicebus oenanthe in northern Peru.

    Science.gov (United States)

    Deluycker, Anneke M

    2012-05-01

    Titi monkeys (genus Callicebus) are small-bodied platyrrhines that supplement their predominantly frugivorous diet with variable amounts of leaves, seeds, and/or arthropod prey. Notable interspecific variation in the amount of insect prey in the diet has been observed in Callicebus, ranging from 0% to 20%. In this study, I investigate the degree and type of prey foraging in a little-known species, Callicebus oenanthe inhabiting a fragmented, secondary forest on the foothills of the Andes in northern Peru. I present data on prey type, prey search and capture techniques, substrate/vegetation use, foraging height, prey capture efficiency, and seasonal variation of insect prey foraging in one group of C. oenanthe observed from January to August 2005. Insect prey accounted for 22% of the diet, the highest amount reported for any Callicebus species to date, and insects from at least six different orders were included. C. oenanthe was mainly an investigative forager of hidden prey, manipulating easy-to-open substrates such as rolled up leaves, and hunted ant swarms and larger insects opportunistically. Insect foraging was predominant during the dry season (26%) and decreased during the wet season (13%). The study group foraged mostly in the understory (2-6 m) within vine-laden shrubs and trees, which may conform to an anti-predator strategy of crypticity. Overall the group had an 83% insect capture success rate. These data suggest that insect prey is an important part of the diet of C. oenanthe and may be especially notable during periods of resource scarcity. This study adds to the knowledge concerning insect prey foraging in Callicebus, which can have an important role in defining ecological strategies in the selection of secondary protein food resources within a given ecosystem.

  1. Modelling foraging movements of diving predators: a theoretical study exploring the effect of heterogeneous landscapes on foraging efficiency.

    Science.gov (United States)

    Chimienti, Marianna; Bartoń, Kamil A; Scott, Beth E; Travis, Justin M J

    2014-01-01

    Foraging in the marine environment presents particular challenges for air-breathing predators. Information about prey capture rates, the strategies that diving predators use to maximise prey encounter rates and foraging success are still largely unknown and difficult to observe. As well, with the growing awareness of potential climate change impacts and the increasing interest in the development of renewable sources it is unknown how the foraging activity of diving predators such as seabirds will respond to both the presence of underwater structures and the potential corresponding changes in prey distributions. Motivated by this issue we developed a theoretical model to gain general understanding of how the foraging efficiency of diving predators may vary according to landscape structure and foraging strategy. Our theoretical model highlights that animal movements, intervals between prey capture and foraging efficiency are likely to critically depend on the distribution of the prey resource and the size and distribution of introduced underwater structures. For multiple prey loaders, changes in prey distribution affected the searching time necessary to catch a set amount of prey which in turn affected the foraging efficiency. The spatial aggregation of prey around small devices (∼ 9 × 9 m) created a valuable habitat for a successful foraging activity resulting in shorter intervals between prey captures and higher foraging efficiency. The presence of large devices (∼ 24 × 24 m) however represented an obstacle for predator movement, thus increasing the intervals between prey captures. In contrast, for single prey loaders the introduction of spatial aggregation of the resources did not represent an advantage suggesting that their foraging efficiency is more strongly affected by other factors such as the timing to find the first prey item which was found to occur faster in the presence of large devices. The development of this theoretical model represents a useful

  2. Effect of wheat forage maturity and preservation method on forage chemical composition and performance of growing calves fed mixed diets.

    Science.gov (United States)

    Beck, P A; Stewart, C B; Gray, H C; Smith, J L; Gunter, S A

    2009-12-01

    Three 2.4-ha wheat (Triticum aestivum L.) fields were used to test the effects of maturity at harvest (boot vs. dough) and preservation method (hay vs. silage) on forage yield, chemical composition, and animal performance when fed in mixed diets. Forages were incorporated into 4 diets in a 2 x 2 factorial arrangement of treatments with hominy feed, soybean hulls, and cottonseed meal as the primary concentrate ingredients. In Exp. 1 diets contained 20% wheat forage (DM basis) and were fed to 96 beef calves (n = 48 steers and 48 heifers; initial BW 229 +/- 6.0 kg) in 12 mixed-sex pens. In Exp. 2 diets contained 40% wheat forage (DM basis) and were fed to beef steers (n = 48; initial BW 198 +/- 6.8 kg) in 12 pens. These diets were also individually fed to 32 calves (Exp. 1, n = 16, BW = 187 +/- 9.4 kg; Exp. 2, n = 16 calves, BW = 160 +/- 8.2 kg) to determine DM and NDF digestibility and gastrointestinal tract passage kinetics. Advanced maturity increased (P or= 0.22) NDF, ADF, or TDN concentrations. Maturity at harvest, preservation method, or their interaction did not affect (P >or= 0.15) ADG when wheat forage was fed as 20 or 40% of the diet. When calves were fed the 40% wheat forage diets, maturity at harvest did not affect (P >or= 0.27) DMI or G:F. Calves fed 40% hay diets consumed more (P = 0.04) feed DM as a percentage of BW than calves fed silage diets, but tended (P = 0.09) to be less efficient. With 20 or 40% wheat forage diets, there were no differences (P >or= 0.13) in passage rate, ruminal retention time, or fecal output due to maturity or preservation method. Digestibility of DM tended (P = 0.07) to be greater for silage than hay diets when fed in 20% wheat forage diets. Dry matter and NDF digestibility of 40% boot-stage wheat forage diets were greater (P wheat forage.

  3. Contact rate modulates foraging efficiency in leaf cutting ants.

    Science.gov (United States)

    Bouchebti, S; Ferrere, S; Vittori, K; Latil, G; Dussutour, A; Fourcassié, V

    2015-12-21

    Lane segregation is rarely observed in animals that move in bidirectional flows. Consequently, these animals generally experience a high rate of head-on collisions during their journeys. Although these collisions have a cost (each collision induces a delay resulting in a decrease of individual speed), they could also have a benefit by promoting information transfer between individuals. Here we explore the impact of head-on collisions in leaf-cutting ants moving on foraging trails by artificially decreasing the rate of head-on collisions between individuals. We show that head-on collisions do not influence the rate of recruitment in these ants but do influence foraging efficiency, i.e. the proportion of ants returning to the nest with a leaf fragment. Surprisingly, both unladen and laden ants returning to the nest participate in the modulation of foraging efficiency: foraging efficiency decreases when the rate of contacts with both nestbound laden or unladen ants decreases. These results suggest that outgoing ants are able to collect information from inbound ants even when these latter do not carry any leaf fragment and that this information can influence their foraging decisions when reaching the end of the trail.

  4. TILLING in forage grasses for gene discovery and breeding improvement.

    Science.gov (United States)

    Manzanares, Chloe; Yates, Steven; Ruckle, Michael; Nay, Michelle; Studer, Bruno

    2016-09-25

    Mutation breeding has a long-standing history and in some major crop species, many of the most important cultivars have their origin in germplasm generated by mutation induction. For almost two decades, methods for TILLING (Targeting Induced Local Lesions IN Genomes) have been established in model plant species such as Arabidopsis (Arabidopsis thaliana L.), enabling the functional analysis of genes. Recent advances in mutation detection by second generation sequencing technology have brought its utility to major crop species. However, it has remained difficult to apply similar approaches in forage and turf grasses, mainly due to their outbreeding nature maintained by an efficient self-incompatibility system. Starting with a description of the extent to which traditional mutagenesis methods have contributed to crop yield increase in the past, this review focuses on technological approaches to implement TILLING-based strategies for the improvement of forage grass breeding through forward and reverse genetics. We present first results from TILLING in allogamous forage grasses for traits such as stress tolerance and evaluate prospects for rapid implementation of beneficial alleles to forage grass breeding. In conclusion, large-scale induced mutation resources, used for forward genetic screens, constitute a valuable tool to increase the genetic diversity for breeding and can be generated with relatively small investments in forage grasses. Furthermore, large libraries of sequenced mutations can be readily established, providing enhanced opportunities to discover mutations in genes controlling traits of agricultural importance and to study gene functions by reverse genetics.

  5. Analysis of adaptive foraging in an intraguild predation system

    Directory of Open Access Journals (Sweden)

    T. Okuyama

    2003-09-01

    Full Text Available An intraguild predation (IGP system with adaptive foraging behavior was analyzed using a simple mathematical model. The main aim was to explore how the adaptive behavior affects species interactions as well as how such interactions derived from adaptive behavior affect community stability. The focal system contained top predators, intermediate predators, and basal prey. Intermediate predators exhibit antipredator behavior and balance costs (e.g. perceived predation risk and benefits (e.g. resource intake to determine their foraging effort. Density-dependent foraging behavior with the unique connectance of the IGP food web created unusual species interactions. Notably, increased prey density can transmit negative indirect effects to top predators while increased top predator density transmits positive indirect effects to prey population. The nature of these interactions is density-dependent. The results suggest that both IGP (as opposed to linear food chain and adaptive foraging behaviors may strongly influence community dynamics due to emergent interactions among direct effects and indirect effects. Furthermore, the adaptive foraging of intermediate predators may stabilize the community as a whole.

  6. Genotypic Differences of Forage Crop Tolerance to Acid Soils

    Institute of Scientific and Technical Information of China (English)

    YANGYUAI; CHUXIANGYUN; 等

    1998-01-01

    Twenty eight species of forage crops were planted on acid soils derived from Quaternary red clay(pH4.16) and red sandstone(pH4.55) to study genotypic differences of the forage crops in tolerance to acid soils as affected by liming,phosporus and potassium fertilizer application.Eight forage species,Lolium nultiflorum L., Brachiaria decumbens,Digitaria sumtisii,Melinis minutiflora,Paspalum dilatatum,Paspalum wettsteinii,Sataria viridis Beanv and Shcep's Festuca,were highly toleran to acid soils,and grew relatively well in the tested soils without lime application,whereas most of the other 20 tested forage species such as Lolium perenne L., Meadow Festuca and Trifolium praense L. were intolerant to acid soil ,showing retarded growth when the soil pH was below 5.5 and significant increase in dry matter yields by phosphrus fertilizer application at soil pH 6.0 Results showed that large differences in tolerance to acid soils existed among the forage species,and tolerance of the froage species to acid soils might be closely associated with their tolerance to Al and P efficiency.

  7. Balancing selection shapes density-dependent foraging behaviour.

    Science.gov (United States)

    Greene, Joshua S; Brown, Maximillian; Dobosiewicz, May; Ishida, Itzel G; Macosko, Evan Z; Zhang, Xinxing; Butcher, Rebecca A; Cline, Devin J; McGrath, Patrick T; Bargmann, Cornelia I

    2016-11-10

    The optimal foraging strategy in a given environment depends on the number of competing individuals and their behavioural strategies. Little is known about the genes and neural circuits that integrate social information into foraging decisions. Here we show that ascaroside pheromones, small glycolipids that signal population density, suppress exploratory foraging in Caenorhabditis elegans, and that heritable variation in this behaviour generates alternative foraging strategies. We find that natural C. elegans isolates differ in their sensitivity to the potent ascaroside icas#9 (IC-asc-C5). A quantitative trait locus (QTL) regulating icas#9 sensitivity includes srx-43, a G-protein-coupled icas#9 receptor that acts in the ASI class of sensory neurons to suppress exploration. Two ancient haplotypes associated with this QTL confer competitive growth advantages that depend on ascaroside secretion, its detection by srx-43 and the distribution of food. These results suggest that balancing selection at the srx-43 locus generates alternative density-dependent behaviours, fulfilling a prediction of foraging game theory.

  8. Influence of landscape structure and human modifications on insect biomass and bat foraging activity in an urban landscape.

    Directory of Open Access Journals (Sweden)

    Caragh G Threlfall

    Full Text Available Urban landscapes are often located in biologically diverse, productive regions. As such, urbanization may have dramatic consequences for this diversity, largely due to changes in the structure and function of urban communities. We examined the influence of landscape productivity (indexed by geology, housing density and vegetation clearing on the spatial distribution of nocturnal insect biomass and the foraging activity of insectivorous bats in the urban landscape of Sydney, Australia. Nocturnal insect biomass (g and bat foraging activity were sampled from 113 sites representing backyard, open space, bushland and riparian landscape elements, across urban, suburban and vegetated landscapes within 60 km of Sydney's Central Business District. We found that insect biomass was at least an order of magnitude greater within suburban landscapes in bushland and backyard elements located on the most fertile shale influenced geologies (both p<0.001 compared to nutrient poor sandstone landscapes. Similarly, the feeding activity of bats was greatest in bushland, and riparian elements within suburbs on fertile geologies (p = 0.039. Regression tree analysis indicated that the same three variables explained the major proportion of the variation in insect biomass and bat foraging activity. These were ambient temperature (positive, housing density (negative and the percent of fertile shale geologies (positive in the landscape; however variation in insect biomass did not directly explain bat foraging activity. We suggest that prey may be unavailable to bats in highly urbanized areas if these areas are avoided by many species, suggesting that reduced feeding activity may reflect under-use of urban habitats by bats. Restoration activities to improve ecological function and maintain the activity of a diversity of bat species should focus on maintaining and restoring bushland and riparian habitat, particularly in areas with fertile geology as these were key bat

  9. Legumes and forage species sole or intercropped with corn in soybean-corn succession in midwestern Brazil

    Directory of Open Access Journals (Sweden)

    Gessí Ceccon

    2013-02-01

    Full Text Available The feasibility of no-tillage in the Cerrado (Savanna-like vegetation of Brazil depends on the production of sufficient above-ground crop residue, which can be increased by corn-forage intercropping. This study evaluated how above-ground crop residue production and yields of soybean and late-season corn in a soybean-corn rotation were influenced by the following crops in the year before soybean: corn (Zea mays L. intercropped with Brachiaria (Urochloa brizantha cv. Marandu, B. decumbens cv. Basilisk, B. ruziziensis, cv. comum., Panicummaximum cv. Tanzânia, sunn hemp (Crotalaria juncea L., pigeon pea [Cajanus cajan (L. Millsp]; sole corn, forage sorghum [Sorghum bicolor (L. Moench (cv. Santa Elisa], and ruzi grass. In March 2005, corn and forage species were planted in alternate rows spaced 0.90 m apart, and sole forage species were planted in rows spaced 0.45 m apart. In October 2005, the forages were killed with glyphosate and soybean was planted. After the soybean harvest in March 2006, sole late-season corn was planted in the entire experimental area. Corn grain and stover yields were unaffected by intercropping. Above-ground crop residue was greater when corn was intercropped with Tanzania grass (10.7 Mg ha-1, Marandu (10.1 Mg ha-1, and Ruzi Grass (9.8 Mg ha-1 than when corn was not intercropped (4.0 Mg ha-1. The intercropped treatments increased the percentage of soil surface covered with crop residue. Soybean and corn grain yields were higher after sole ruzi grass and intercropped ruzi grass than after other crops. The intercropping corn with Brachiaria spp. and corn with Panicum spp. increases above-ground crop residue production and maintains nutrients in the soil without reducing late-season corn yield and the viability of no-till in the midwestern region of Brazil.

  10. An Investigation on Physiological and Photosynthetic Parameters of Forage Maize at Regulated Deficit Irrigation and Partial Root Zone Draying Methods

    Directory of Open Access Journals (Sweden)

    Nader Naderi

    2017-02-01

    Full Text Available Introduction: Water shortage is the most important factor affecting crop production in the world. The deficit irrigation is a way to reduce water consumption in farming. The Partial Root- zone Drying (PRD irrigation is a new improvement in deficit irrigation in which the half of the root zone is irrigated alternatively in scheduled irrigation events. In the fixed partial root zone drying (FPRD the irrigation is fixed to one side of the root zone in the growing season. Maize is a drought sensitive crop. In maize, secondary traits related to drought resistance are considered in producing tolerate cultivars. Materials and Methods: An experiment was conducted in order to investigate the effects of regulated deficit irrigation, variable partial root zone drying (PRD and fixed partial root zone drying (FPRD on the yield, physiological and photosynthetic parameters of forage maize (KSC 704 during the growing seasons of 2014 in Mashhad region. A factorial experiment based on randomized complete block design with four replications was carried out. The treatments included the full irrigation (FI and the deficit irrigations (regulated deficit irrigation (DI and the replacements of 80 % (DI80 and 60 % (DI60 of total water requirement, fixed PRD (FPRD at 100% (FPRD100, 80% (FPRD80 and 60%(FPRD60 of water requirement, and variable PRD at 100% (PRD100, 80% (PRD80 and 60% (PRD60 of water requirement. Drip irrigation tapes were placed between plant rows. In the full irrigation and regulated deficit irrigation treatments, the plants were irrigated from two sides for every irrigation. In the PRD, one of two neighboring tapes was alternatively used for irrigation. In FPRD, a drip tape was used for two plant rows and irrigation was fixed to one side of the root. The irrigation interval was 3 days for all treatments. Dry and fresh forage yield, leaf area index (LAI, stomatal conductance, leaf relative water content (RWC and chlorophyll content were measured. Results

  11. Use of electroreception during foraging by the Australian lungfish.

    Science.gov (United States)

    Watt; Evans; Joss

    1999-11-01

    A diverse range of animals, including elasmobranchs and nonteleost fish, use passive electroreception to locate hidden prey. The Australian lungfish, Neoceratodus forsteri (Krefft 1870), has ampullary organs analogous in form to the electroreceptors of other nonteleost fish. Afferents from these ampullae project to regions in the brain that are known to process electrosensory information in other species, suggesting that N. forsteri possesses an electric sense that may be used during prey location. To explore this hypothesis directly, we first characterized food-locating behaviour in N. forsteri and then conducted an experiment designed to quantify the effects of manipulating electrical and olfactory stimuli from live prey. A small crayfish, Cherax destructor, was housed in a specially constructed chamber hidden beneath the substrate, which prevented emission of chemical, mechanical and visual cues, but allowed transmission of bioelectric fields. Control treatments included presentation of electrically shielded prey, a dead crayfish and an empty chamber. In some treatments, a competing olfactory signal was presented simultaneously at the other end of the test tank to assess the relative salience of this sensory modality. The lungfish responded to the crayfish in the unshielded chamber with accurate and sustained feeding movements, even with a competing olfactory signal. By contrast, the abolition of electrical cues in the three control treatments reduced the accuracy and frequency of feeding movements in the vicinity of the target chamber. These results show that N. forsteri is capable of perceiving the weak electric fields surrounding living animals, and suggest that it uses this information when foraging to locate prey hidden from view. Copyright 1999 The Association for the Study of Animal Behaviour.

  12. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico

    Science.gov (United States)

    Shaver, Donna J; Hart, Kristen M; Fujisaki, Ikuko; Rubio, Cynthia; Sartain, Autumn R; Peña, Jaime; Burchfield, Patrick M; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-01-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998–2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their “final” foraging sites. We identified new foraging “hotspots” where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species. PMID:23919146

  13. Nitrogen and carbon isotope values of individual amino acids: a tool to study foraging ecology of penguins in the Southern Ocean

    NARCIS (Netherlands)

    Lorrain, A.; Graham, B.; Ménard, F.; Popp, B.; Bouillon, S.; Van Breugel, P.; Cherel, Y.

    2009-01-01

    We determined the δ15N and δ13C values of individual amino acids (AAs) isolated from chick blood of 4 penguin species that forage in different oceanic regions (from the subtropics of the Indian Ocean to Antarctica) to test if: (1) the δ15N values of phenylalanine (δ15N phe) revealed different foragi

  14. The influence of forage diets and aging on beef palatability.

    Science.gov (United States)

    Jiang, T; Busboom, J R; Nelson, M L; O'Fallon, J; Ringkob, T P; Rogers-Klette, K R; Joos, D; Piper, K

    2010-11-01

    To investigate the influence of diet and aging on beef palatability, lipid oxidative stability, and fatty acid composition, crossbred steers were assigned to Feedlot S (alfalfa and grain), Forage TR (triticale and annual ryegrass), Forage TK (triticale and kale), or Forage+Feedlot (grazing ryegrass, fescue and orchardgrass, finished on alfalfa and grain) dietary treatments. Heifers were finished on Feedlot H (alfalfa and grain). Longissimus and tricep muscles were sampled from these animals for steaks and ground beef, respectively. Steaks were either dry- or wet-aged for 14 d. Ground beef was dry-aged, wet-aged for 14 d, or not aged. Trained sensory panelists evaluated palatability attributes of steaks and ground beef. Diet did not influence sensory attributes of steaks or ground beef. Aging impacted (Pbeef. Diet and aging had no impact on lipid oxidative stability but affected fatty acid composition of raw ground beef.

  15. SOCIAL COMPLEXITY AND LEARNING FORAGING TASKS IN BEES

    Directory of Open Access Journals (Sweden)

    AMAYA-MÁRQUEZ MARISOL

    2008-12-01

    Full Text Available Social complexity and models concerning central place foraging were tested with respect to learning predictions using the social honey bee (Apis mellifera and solitary blue orchard bee (Osmia lignaria when given foraging problems. Both species were presented the same foraging problems, where 1 only reward molarity varied between flower morphs, and 2 only reward volume varied between flower morphs. Experiments utilized blue vs. white flower patches to standardize rewards in each experimental situation. Although honey bees learned faster than blue orchard bees when given a molarity difference reward problem, there was no significant difference in learning rate when presented a volume difference reward problem. Further, the rate at which blue orchard bees learned the volume difference problem was not significantly different from that with which honey bees learned about reward molarity differences. The results do not support the predictions of the social complexity theory, but do support those of the central place model

  16. Trait-mediated trophic interactions: is foraging theory keeping up?

    Science.gov (United States)

    Railsback, Steven F; Harvey, Bret C

    2013-02-01

    Many ecologists believe that there is a lack of foraging theory that works in community contexts, for populations of unique individuals each making trade-offs between food and risk that are subject to feedbacks from behavior of others. Such theory is necessary to reproduce the trait-mediated trophic interactions now recognized as widespread and strong. Game theory can address feedbacks but does not provide foraging theory for unique individuals in variable environments. 'State- and prediction-based theory' (SPT) is a new approach that combines existing trade-off methods with routine updating: individuals regularly predict future food availability and risk from current conditions to optimize a fitness measure. SPT can reproduce a variety of realistic foraging behaviors and trait-mediated trophic interactions with feedbacks, even when the environment is unpredictable.

  17. Forage herbs improve mineral composition of grassland herbage

    DEFF Research Database (Denmark)

    Pirhofer-Walzl, Karin; Søegaard, Karen; Jensen, Henning Høgh

    2011-01-01

    Provision of an adequate mineral supply in the diets of ruminants fed mainly on grassland herbage can present a challenge if mineral concentrations are suboptimal for animal nutrition. Forage herbs may be included in grassland seed mixtures to improve herbage mineral content, although...... there is limited information about mineral concentrations in forage herbs. To determine whether herbs have greater macro- and micromineral concentrations than forage legumes and grasses, we conducted a 2-year experiment on a loamy-sand site in Denmark sown with a multi-species mixture comprised of three functional......, legumes and herbs. In general, herbs had greater concentrations of the macrominerals P, Mg, K and S and the microminerals Zn and B than grasses and legumes. Slurry application indirectly decreased Ca, S, Cu and B concentrations of total herbage because of an increase in the proportion of mineral...

  18. The Müller-Lyer illusion in ant foraging.

    Science.gov (United States)

    Sakiyama, Tomoko; Gunji, Yukio-Pegio

    2013-01-01

    The Müller-Lyer illusion is a classical geometric illusion in which the apparent (perceived) length of a line depends on whether the line terminates in an arrow tail or arrowhead. This effect may be caused by economic compensation for the gap between the physical stimulus and visual fields. Here, we show that the Müller-Lyer illusion can also be produced by the foraging patterns of garden ants (Lasius niger) and that the pattern obtained can be explained by a simple, asynchronously updated foraging ant model. Our results suggest that the geometric illusion may be a byproduct of the foraging process, in which local interactions underlying efficient exploitation can also give rise to global exploration, and that visual information processing in human could implement similar modulation between local efficient processing and widespread computation.

  19. The Muller-Lyer illusion in ant foraging.

    Directory of Open Access Journals (Sweden)

    Tomoko Sakiyama

    Full Text Available The Müller-Lyer illusion is a classical geometric illusion in which the apparent (perceived length of a line depends on whether the line terminates in an arrow tail or arrowhead. This effect may be caused by economic compensation for the gap between the physical stimulus and visual fields. Here, we show that the Müller-Lyer illusion can also be produced by the foraging patterns of garden ants (Lasius niger and that the pattern obtained can be explained by a simple, asynchronously updated foraging ant model. Our results suggest that the geometric illusion may be a byproduct of the foraging process, in which local interactions underlying efficient exploitation can also give rise to global exploration, and that visual information processing in human could implement similar modulation between local efficient processing and widespread computation.

  20. Dynamic optimal foraging theory explains vertical migrations of bigeye tuna

    DEFF Research Database (Denmark)

    Thygesen, Uffe Høgsbro; Sommer, Lene; Evans, Karen;

    2016-01-01

    Bigeye tuna are known for remarkable daytime vertical migrations between deep water, where food is abundant but the water is cold, and the surface, where water is warm but food is relatively scarce. Here we investigate if these dive patterns can be explained by dynamic optimal foraging theory......, where the tuna maximizes its energy harvest rate. We assume that foraging efficiency increases with body temperature, so that the vertical migrations are thermoregulatory. The tuna's state is characterized by its mean body temperature and depth, and we solve the optimization problem numerically using...... behaves such as to maximize its energy gains. The model therefore provides insight into the processes underlying observed behavioral patterns and allows generating predictions of foraging behavior in unobserved environments...

  1. Evolution of Optimum Foraging Distributions in Two Dimensions

    Science.gov (United States)

    Dees, Nathan; Bahar, Sonya; Moss, Frank

    2008-03-01

    In the pursuit of optimally efficient foraging, preferred distributions of movement characteristics have been shown to exist for many types of animals and environments. Specifically, planktonic organisms such as Daphnia use exponential distributions of turning angles, α, in a ``hop, pause, turn by angle α, hop'' random walk-type sequence of movement when traversing experimentally prepared feeding solutions consisting of freeze dried Spirolina and water. We investigate the evolution of such random walks in a two-dimensional foraging model. In this model, agents traverse a feeding patch of finite size and for a finite amount of time using hop lengths and turning angles chosen randomly from inherited distributions. Distributions evolve as the choices made by the most efficient forager of one generation influence the distributions available to the succeeding generation. Preliminary results show that initially uniform turning angle distributions evolve to explicit exponential distributions after thousands of generations, consistent with the experimental observations described above.

  2. Contrafreeloading in grizzly bears: implications for captive foraging enrichment.

    Science.gov (United States)

    McGowan, Ragen T S; Robbins, Charles T; Alldredge, J Richard; Newberry, Ruth C

    2010-01-01

    Although traditional feeding regimens for captive animals were focused on meeting physiological needs to assure good health, more recently emphasis has also been placed on non-nutritive aspects of feeding. The provision of foraging materials to diversify feeding behavior is a common practice in zoos but selective consumption of foraging enrichment items over more balanced "chow" diets could lead to nutrient imbalance. One alternative is to provide balanced diets in a contrafreeloading paradigm. Contrafreeloading occurs when animals choose resources that require effort to exploit when identical resources are freely available. To investigate contrafreeloading and its potential as a theoretical foundation for foraging enrichment, we conducted two experiments with captive grizzly bears (Ursus arctos horribilis). In Experiment 1, bears were presented with five foraging choices simultaneously: apples, apples in ice, salmon, salmon in ice, and plain ice under two levels of food restriction. Two measures of contrafreeloading were considered: weight of earned food consumed and time spent working for earned food. More free than earned food was eaten, with only two bears consuming food extracted from ice, but all bears spent more time manipulating ice containing salmon or apples than plain ice regardless of level of food restriction. In Experiment 2, food-restricted bears were presented with three foraging choices simultaneously: apples, apples inside a box, and an empty box. Although they ate more free than earned food, five bears consumed food from boxes and all spent more time manipulating boxes containing apples than empty boxes. Our findings support the provision of contrafreeloading opportunities as a foraging enrichment strategy for captive wildlife.

  3. Genetic stock compositions and natal origin of green turtle (Chelonia mydas foraging at Brunei Bay

    Directory of Open Access Journals (Sweden)

    Juanita Joseph

    2016-04-01

    Full Text Available Knowledge of genetics composition and growth stages of endangered green turtles, as well as the connectivity between nesting and foraging grounds is important for effective conservation. A total of 42 green turtles were captured at Brunei Bay with curved carapace length ranging from 43.8 to 102.0 cm, and most sampled individuals were adults and large juveniles. Twelve haplotypes were revealed in mitochondrial DNA control region sequences. Most haplotypes contained identical sequences to haplotypes previously found in rookeries in the Western Pacific, Southeast Asia, and the Indian Ocean. Haplotype and nucleotide diversity indices of the Brunei Bay were 0.8444±0.0390 and 0.009350±0.004964, respectively. Mixed-stock analysis (for both uninformative and informative prior weighting by population size estimated the main contribution from the Southeast Asian rookeries of the Sulu Sea (mean ≥45.31%, Peninsular Malaysia (mean ≥17.42%, and Sarawak (mean ≥12.46%. Particularly, contribution from the Sulu Sea rookery was estimated to be the highest and lower confidence intervals were more than zero (≥24.36%. When estimating contributions by region rather than individual rookeries, results showed that Brunei Bay was sourced mainly from the Southeast Asian rookeries. The results suggest an ontogenetic shift in foraging grounds and provide conservation implications for Southeast Asian green turtles.

  4. Children on the reef : Slow learning or strategic foraging?

    Science.gov (United States)

    Bird, Douglas W; Bliege Bird, Rebecca

    2002-06-01

    Meriam children are active reef-flat collectors. We demonstrate that while foraging on the reef, children are significantly less selective than adults. This difference and the precise nature of children's selectivity while reef-flat collecting are consistent with a hypothesis that both children and adults attempt to maximize their rate of return while foraging, but in so doing they face different constraints relative to differences in walking speeds while searching. Implications of these results for general arguments about factors that shape differences between child and adult behavior and human life-histories are explored.

  5. Forage use to improve environmental sustainability of ruminant production.

    Science.gov (United States)

    Guyader, J; Janzen, H H; Kroebel, R; Beauchemin, K A

    2016-08-01

    Ruminants raised for meat and milk are important sources of protein in human diets worldwide. Their unique digestive system allows them to derive energy and nourishment from forages, making use of vast areas of grazing lands not suitable for arable cropping or biofuel production and avoiding direct competition for grain that can be used as human food. However, sustaining an ever-growing population of ruminants consuming forages poses a dilemma: while exploiting their ecological niche, forage-fed ruminants produce large amount of enteric methane, a potent greenhouse gas. Resolving this quandary would allow ruminants an expanded role in meeting growing global demands for livestock products. One way around the dilemma is to devise forage-based diets and feeding systems that reduce methane emissions per unit of milk or meat produced. Ongoing research has made significant strides toward this objective. A wider opportunity is to look beyond methane emissions alone and consider all greenhouse gas emissions from the entire livestock-producing system. For example, by raising ruminants in systems using forages, some of the methane emissions can be offset by preserving or enhancing soil carbon reserves, thereby withholding carbon dioxide from the air. Similarly, well-managed systems based on forages may reduce synthetic fertilizer use by more effective use of manure and nitrogen-fixing plants, thereby curtailing nitrous oxide emissions. The potential environmental benefits of forage-based systems may be expanded even further by considering their other ecological benefits, such as conserving biodiversity, improving soil health, enhancing water quality, and providing wildlife habitat. The quandary, then, can be alleviated by managing ruminants within a holistic land-livestock synchrony that considers not only methane emissions but also suppression of other greenhouse gases as well as other ecological benefits. Given the complexity of such systems, there likely are no singular

  6. Optimal foraging and beyond : How starlings cope with changes in food availability

    NARCIS (Netherlands)

    Bautista, LM; Tinbergen, J; Wiersma, P; Kacelnik, A; Bautista, Luis M.; Byers, John A.

    1998-01-01

    Foraging adaptations include behavioral and physiological responses, but most optimal foraging models deal exclusively with behavioral decision variables, taking other dimensions as constraints. To overcome this limitation, we measured behavioral and physiological responses of European starlings Stu

  7. A self-limiting complete feed changes forage intake and animal ...

    African Journals Online (AJOL)

    South African Society for Animal Science ... 1 Texas Agricultural Experiment Station, Stephenville, TX 76401, USA. '2Tar1eton State ... in growing goats, but can result in decreased forage consumption due to substitution of forage intake with.

  8. Game-Theoretic Methods for Functional Response and Optimal Foraging Behavior: e88773

    National Research Council Canada - National Science Library

    Ross Cressman; Vlastimil Krivan; Joel S Brown; József Garay

    2014-01-01

    ... the corresponding functional response. It is shown that the optimal foraging behavior that maximizes predator energy intake per unit time is a Nash equilibrium of the underlying optimal foraging game...

  9. A mathematical model of foraging in a dynamic environment by trail-laying Argentine ants.

    Science.gov (United States)

    Ramsch, Kai; Reid, Chris R; Beekman, Madeleine; Middendorf, Martin

    2012-08-07

    Ants live in dynamically changing environments, where food sources become depleted and alternative sources appear. Yet most mathematical models of ant foraging assume that the ants' foraging environment is static. Here we describe a mathematical model of ant foraging in a dynamic environment. Our model attempts to explain recent empirical data on dynamic foraging in the Argentine ant Linepithema humile (Mayr). The ants are able to find the shortest path in a Towers of Hanoi maze, a complex network containing 32,768 alternative paths, even when the maze is altered dynamically. We modify existing models developed to explain ant foraging in static environments, to elucidate what possible mechanisms allow the ants to quickly adapt to changes in their foraging environment. Our results suggest that navigation of individual ants based on a combination of one pheromone deposited during foraging and directional information enables the ants to adapt their foraging trails and recreates the experimental results. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Foraging reactivation in the honeybee Apis mellifera L.: factors affecting the return to known nectar sources

    Science.gov (United States)

    Gil, Mariana; Farina, Walter Marcelo

    2002-05-01

    This paper addresses, what determines that experienced forager honeybees return to places where they have previously exploited nectar. Although there was already some evidence that dance and trophallaxis can cause bees to return to feed, the fraction of unemployed foragers that follow dance or receive food from employed foragers before revisiting the feeder was unknown. We found that 27% of the experienced foragers had no contact with the returning foragers inside the hive. The most common interactions were dance following (64%) and trophallaxis (21%). The great variability found in the amount of interactions suggests that individual bees require different stimulation before changing to the foraging mode. This broad disparity negatively correlated with the number of days after marking at the feeder, a variable that is closely related to the foraging experience, suggesting that a temporal variable might affect the decision-making in reactivated foragers.

  11. The Physiological Suppressing Factors of Dry Forage Intake and the Cause of Water Intake Following Dry Forage Feeding in Goats - A Review.

    Science.gov (United States)

    Sunagawa, Katsunori; Nagamine, Itsuki

    2016-02-01

    The goats raised in the barn are usually fed on fresh grass. As dry forage can be stored for long periods in large amounts, dry forage feeding makes it possible to feed large numbers of goats in barns. This review explains the physiological factors involved in suppressing dry forage intake and the cause of drinking following dry forage feeding. Ruminants consume an enormous amount of dry forage in a short time. Eating rates of dry forage rapidly decreased in the first 40 min of feeding and subsequently declined gradually to low states in the remaining time of the feeding period. Saliva in large-type goats is secreted in large volume during the first hour after the commencement of dry forage feeding. It was elucidated that the marked suppression of dry forage intake during the first hour was caused by a feeding-induced hypovolemia and the loss of NaHCO3 due to excessive salivation during the initial stages of dry forage feeding. On the other hand, it was indicated that the marked decrease in feed intake observed in the second hour of the 2 h feeding period was related to ruminal distension caused by the feed consumed and the copious amount of saliva secreted during dry forage feeding. In addition, results indicate that the marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding. After 40 min of the 2 h dry forage feeding period, the feed salt content is absorbed into the rumen and plasma osmolality increases. The combined effects of ruminal distension and increased plasma osmolality accounted for 77.6% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality are the main physiological factors in suppression of dry forage intake in large-type goats. There was very little drinking behavior observed during the first hour of the 2 h feeding period most

  12. Modeling of Habitat and Foraging Behavior of Beaked Whales in the Southern California Bight

    Science.gov (United States)

    2015-09-30

    whale distribution and foraging behavior and to describe inter -specific differences. We investigated spatio-temporal patterns for Cuvier’s beaked whale...distribution and foraging behavior and to describe inter -specific differences. Knowledge about foraging behavior and habitat preference and...Foraging bouts (buzzes) were automatically detected by an algorithm that searched for consecutive low inter -click intervals (5-10 ms) and low received

  13. Enteric methane production and ruminal fermentation from forage brassica diets fed in continuous culture

    Science.gov (United States)

    Brassicas provide forage for livestock during the late fall when traditional perennial cool-season forages are not productive. However, little research exists on ruminal fermentation and methane(CH4) production of brassicas fed as forage. A continuous culture fermentor system was used to assess nutr...

  14. [Study on foraging behaviors of honeybee Apis mellifera based on RFID technology].

    Science.gov (United States)

    Tian, Liu-Qing; He, Xu-Jiang; Wu, Xiao-Bo; Gan, Hai-Yan; Han, Xu; Liu, Hao; Zeng, Zhi-Jiang

    2014-03-01

    Honeybee foragers can flexibly adjust their out-hive activities to ensure growth and reproduction of the colony. In order to explore the characteristics of honey bees foraging behaviors, in this study, their flight activities were monitored 24 hours per day for a duration of 38 days, using an radio frequency identification (RFID) system designed and manufactured by the Honeybee Research Institute of Jiangxi Agricultural University in cooperation with the Guangzhou Invengo Information Technology Co., Ltd. Our results indicated that 63.4% and 64.5% of foragers were found rotating more than one day off during the foraging period in two colonies, and 22.5% and 26.4% of the total foraging days were used for rest respectively. Further, although the total foraging time between rotating day-off foragers and continuously working foragers was equal, the former had a significant longer lifespan than the latter. Additionally, the lifespan of the early developed foragers was significantly lower than that of the normally developed foragers. This study enriched the content of foraging behaviors of honey bees, and it could be used as the basis for the further explorations on evolutionary mechanism of foraging behaviors of eusocial insects.

  15. Breeding Better Forages to Help Feed Man and Preserve and Enhance the Environment

    Science.gov (United States)

    Burton, Glenn W.

    1973-01-01

    Discusses the importance of forages in agriculture, and expresses the need for the same high level of technology that is used in the production of corn, wheat, and rice to be applied to forage production. Describes promising forage species, breeding objectives, and breeding procedures used in research. (JR)

  16. Intake and utilization of energy of rations with pelleted forages by dairy cows

    NARCIS (Netherlands)

    Honing, van der Y.

    1975-01-01

    A survey of the literature showed that forage processing, that is grinding and pelleting, increased feed intake of ruminants. This increase, due to reduction in particle size distribution of the forage, depends mainly on forage quality, proportion of concentrates in the diet and nutrient requirement

  17. Net effects of nitrogen fertilization on the nutritive value and digestibility of oat forages

    Science.gov (United States)

    Applications of soil amendments containing N are part of routine forage management strategies for grasses, with a primary goal of increasing forage yield. However, the effects of N fertilization on forage nutritive value, estimates of energy density, and in-vitro DM or NDF disappearance often have b...

  18. Specialization on pollen or nectar in bumblebee foragers is not associated with ovary size, lipid reserves or sensory tuning

    Directory of Open Access Journals (Sweden)

    Adam R. Smith

    2016-10-01

    Full Text Available Foraging specialization allows social insects to more efficiently exploit resources in their environment. Recent research on honeybees suggests that specialization on pollen or nectar among foragers is linked to reproductive physiology and sensory tuning (the Reproductive Ground-Plan Hypothesis; RGPH. However, our understanding of the underlying physiological relationships in non-Apis bees is still limited. Here we show that the bumblebee Bombus terrestris has specialist pollen and nectar foragers, and test whether foraging specialization in B. terrestris is linked to reproductive physiology, measured as ovarian activation. We show that neither ovary size, sensory sensitivity, measured through proboscis extension response (PER, or whole-body lipid stores differed between pollen foragers, nectar foragers, or generalist foragers. Body size also did not differ between any of these three forager groups. Non-foragers had significantly larger ovaries than foragers. This suggests that potentially reproductive individuals avoid foraging.

  19. Predator personality and prey behavioural predictability jointly determine foraging performance

    Science.gov (United States)

    Chang, Chia-chen; Teo, Huey Yee; Norma-Rashid, Y.; Li, Daiqin

    2017-01-01

    Predator-prey interactions play important roles in ecological communities. Personality, consistent inter-individual differences in behaviour, of predators, prey or both are known to influence inter-specific interactions. An individual may also behave differently under the same situation and the level of such variability may differ between individuals. Such intra-individual variability (IIV) or predictability may be a trait on which selection can also act. A few studies have revealed the joint effect of personality types of both predators and prey on predator foraging performance. However, how personality type and IIV of both predators and prey jointly influence predator foraging performance remains untested empirically. Here, we addressed this using a specialized spider-eating jumping spider, Portia labiata (Salticidae), as the predator, and a jumping spider, Cosmophasis umbratica, as the prey. We examined personality types and IIVs of both P. labiata and C. umbratica and used their inter- and intra-individual behavioural variation as predictors of foraging performance (i.e., number of attempts to capture prey). Personality type and predictability had a joint effect on predator foraging performance. Aggressive predators performed better in capturing unpredictable (high IIV) prey than predictable (low IIV) prey, while docile predators demonstrated better performance when encountering predictable prey. This study highlights the importance of the joint effect of both predator and prey personality types and IIVs on predator-prey interactions. PMID:28094288

  20. Pollen collection and honey bee forager distribution in cantaloupe

    Science.gov (United States)

    Honey bee (Apis mellifera, L.) pollen collection and forager distribution were examined during the summer of 2002 in a cantaloupe (Cucumis melo, L., Cruiser cv.) field provided with plastic mulch and drip irrigation. The experimental site was located near the INIFAP Campo Experimental La Laguna, Ma...

  1. Determination of Phytoestrogen Content in Fresh-Cut Legume Forage

    Directory of Open Access Journals (Sweden)

    Pavlína Hloucalová

    2016-07-01

    Full Text Available The aim of the study was to determine phytoestrogen content in fresh-cut legume forage. This issue has been much discussed in recent years in connection with the health and safety of feedstuffs and thus livestock health. The experiments were carried out on two experimental plots at Troubsko and Vatín, Czech Republic during June and July in 2015. Samples were collected of the four forage legume species perennial red clover (variety “Amos”, alfalfa (variety “Holyně”, and annuals Persian clover and Alexandrian clover. Forage was sampled twice at regular three to four day intervals leading up to harvest and a third time on the day of harvest. Fresh and wilted material was analyzed using liquid chromatography–mass spectrometry (LC-MS. Higher levels ( p < 0.05 of isoflavones biochanin A (3.697 mg·g −1 of dry weight and formononetin (4.315 mg·g −1 of dry weight were found in red clover than in other species. The highest isoflavone content was detected in red clover, reaching 1.001% of dry matter ( p < 0.05, representing a risk for occurrence of reproduction problems and inhibited secretion of animal estrogen. The phytoestrogen content was particularly increased in wilted forage. Significant isoflavone reduction was observed over three to four day intervals leading up to harvest.

  2. Cervid forage utilization in noncommercially thinned ponderosa pine forests

    Science.gov (United States)

    Gibbs, M.C.; Jenks, J.A.; Deperno, C.S.; Sowell, B.F.; Jenkins, Kurt J.

    2004-01-01

    To evaluate effects of noncommercial thinning, utilization of forages consumed by elk (Cervus elaphus L.), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginianus Raf.) was measured in ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in Custer State Park, S. D. Treatments consisted of unthinned (control; 22 to 32 m2/ha basal area), moderately thinned (12 to 22 m2/ha basal area), and heavily thinned (3 to 13 m2/ha basal area) stands of ponderosa pine. During June, July, and August, 1991 and 1992, about 7,000 individual plants were marked along permanent transects and percent-weight-removed by grazing was ocularly estimated. Sample plots were established along transects and plants within plots were clipped to estimate standing biomass. Pellet groups were counted throughout the study area to determine summer habitat use of elk and deer. Diet composition was evaluated using microhistological analysis of fecal samples. Average percent-weight-removed from all marked plants and percent-plants-grazed were used to evaluate forage utilization. Standing biomass of graminoids, shrubs, and forbs increased (P 0.05) across treatments. Forb use averaged less than 5% within sampling periods when measured as percent-weight-removed and percent-of-plants grazed and did not differ among treatments. Results of pellet group surveys indicated that cervids were primarily using meadow habitats. When averaged over the 2 years, forbs were the major forage class in deer diets, whereas graminoids were the major forage class in diets of elk.

  3. Thermodynamic properties of water desorption of forage turnip seeds

    Directory of Open Access Journals (Sweden)

    Kelly Aparecida Sousa

    2014-11-01

    Full Text Available The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip  seeds. The equilibrium moisture content of forage turnip  seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within the moisture content range of 3.33 to 11.30 (% d.b., varies from 4,222.70 to 2,870.34 kJ kg-1. With the elevation in the equilibrium moisture content, there is an increase in differential entropy and Gibbs free energy, which has positive values, demonstrating non-spontaneity in the process of desorption in the seeds. The theory of enthalpy-entropy compensation can be satisfactorily applied to the sorption phenomenon, and the process of water desorption of forage turnip seeds is controlled by enthalpy.

  4. Wild Bee Community Composition and Foraging Behaviour in Commercial Strawberries

    DEFF Research Database (Denmark)

    Ahrenfeldt, Erica Juel

    -nesting polylectic solitary species that are known to forage in the family Rosaceae, to which strawberry belong, which indicate that the bees sampled are a source of pollination in strawberries (I, II). Furthermore, the high proportion of polylectic bees found in Danish strawberry fields indicate that an adaptation...

  5. Air pollutants degrade floral scents and increase insect foraging times

    Science.gov (United States)

    Fuentes, Jose D.; Chamecki, Marcelo; Roulston, T.'ai; Chen, Bicheng; Pratt, Kenneth R.

    2016-09-01

    Flowers emit mixtures of scents that mediate plant-insect interactions such as attracting insect pollinators. Because of their volatile nature, however, floral scents readily react with ozone, nitrate radical, and hydroxyl radical. The result of such reactions is the degradation and the chemical modification of scent plumes downwind of floral sources. Large Eddy Simulations (LES) are developed to investigate dispersion and chemical degradation and modification of floral scents due to reactions with ozone, hydroxyl radical, and nitrate radical within the atmospheric surface layer. Impacts on foraging insects are investigated by utilizing a random walk model to simulate insect search behavior. Results indicate that even moderate air pollutant levels (e.g., ozone mixing ratios greater than 60 parts per billion on a per volume basis, ppbv) substantially degrade floral volatiles and alter the chemical composition of released floral scents. As a result, insect success rates of locating plumes of floral scents were reduced and foraging times increased in polluted air masses due to considerable degradation and changes in the composition of floral scents. Results also indicate that plant-pollinator interactions could be sensitive to changes in floral scent composition, especially if insects are unable to adapt to the modified scentscape. The increase in foraging time could have severe cascading and pernicious impacts on the fitness of foraging insects by reducing the time devoted to other necessary tasks.

  6. Use of Urban Marine Habitats by Foraging Wading Birds

    Science.gov (United States)

    Wading birds that utilize coastal habitats may be at risk from increasing urbanization near their foraging and stopover sites. However, the relative importance of human disturbance in the context of other landscape and biological factors that may be influencing their distributio...

  7. Scrounging by foragers can resolve the paradox of enrichment.

    Science.gov (United States)

    Toyokawa, Wataru

    2017-03-01

    Theoretical models of predator-prey systems predict that sufficient enrichment of prey can generate large amplitude limit cycles, paradoxically causing a high risk of extinction (the paradox of enrichment). Although real ecological communities contain many gregarious species, whose foraging behaviour should be influenced by socially transmitted information, few theoretical studies have examined the possibility that social foraging might resolve this paradox. I considered a predator population in which individuals play the producer-scrounger foraging game in one-prey-one-predator and two-prey-one-predator systems. I analysed the stability of a coexisting equilibrium point in the one-prey system and that of non-equilibrium dynamics in the two-prey system. The results revealed that social foraging could stabilize both systems, and thereby resolve the paradox of enrichment when scrounging behaviour (i.e. kleptoparasitism) is prevalent in predators. This suggests a previously neglected mechanism underlying a powerful effect of group-living animals on the sustainability of ecological communities.

  8. The use of edge habitats by commuting and foraging bats

    NARCIS (Netherlands)

    Verboom, B.

    1998-01-01

    Travelling routes and foraging areas of many bat species are mainly along edge habitats, such as treelines, hedgerows, forest edges, and canal banks. This thesis deals with the effects of density, configuration, and structural features of edge habitats on the occurrence of bats. Four

  9. At-sea associations in foraging little penguins.

    Science.gov (United States)

    Berlincourt, Maud; Arnould, John P Y

    2014-01-01

    Prey distribution, patch size, and the presence of conspecifics are important factors influencing a predator's feeding tactics, including the decision to feed individually or socially. Little is known about group behaviour in seabirds as they spend most of their lives in the marine environment where it is difficult to observe their foraging activities. In this study, we report on at-sea foraging associations of little penguins (Eudyptula minor) during the breeding season. Individuals could be categorised as (1) not associating; (2) associating when departing from and/or returning to the colony; or (3) at sea when travelling, diving or performing synchronised dives. Out of 84 separate foraging tracks, 58 (69.0%) involved associations with conspecifics. Furthermore, in a total of 39 (46.4%), individuals were found to dive during association and in 32 (38.1%), individuals were found to exhibit synchronous diving. These behaviours suggest little penguins forage in groups, could synchronise their underwater movements and potentially cooperate to concentrate their small schooling prey.

  10. Forage fish, their fisheries and their predators: who drives whom?

    NARCIS (Netherlands)

    Engelhard, G.H.; Peck, M.A.; Rindorf, A.; Smout, S.C.; Deurs, van M.; Raab, K.E.; Andersen, K.H.; Garthe, S.; Lauerburg, R.A.M.; Scott, F.; Brunel, T.P.A.; Aarts, G.M.; Kooten, van T.; Dickey-Collas, M.

    2014-01-01

    The North Sea has a diverse forage fish assemblage, including herring, targeted for human consumption; sandeel, sprat, and Norway pout, exploited by industrial fisheries; and some sardine and anchovy, supporting small-scale fisheries. All show large abundance fluctuations, impacting on fisheries and

  11. Predation risk and elk-aspen foraging patterns

    Science.gov (United States)

    Clifford A. White; Michael C. Feller

    2001-01-01

    Elk-aspen foraging patterns may be influenced by cover type, distance from roads or trails, the type of user on road or trail (park visitor, human hunter, or predator), and two general states of aspen condition (open-grown or thicket). Pellet group and browse utilization transects in the Canadian Rockies showed that elk were attracted to roads used by park visitors and...

  12. The use of edge habitats by commuting and foraging bats.

    NARCIS (Netherlands)

    Verboom, B.

    1998-01-01

    Travelling routes and foraging areas of many bat species are mainly along edge habitats, such as treelines, hedgerows, forest edges, and canal banks. This thesis deals with the effects of density, configuration, and structural features of edge habitats on the occurrence of bats. Four hypothetical fu

  13. Variation in foraging activity of Acanthochitona garnoti (Mollusca ...

    African Journals Online (AJOL)

    At all sites, chitons spent a significantly greater (p < 0,00 I; multi factor analysis of ... groups mean groups. Aeolean piforaging is taken into account, actual distances .... hypothesis of trail polymorphism.

  14. Nutrient compensatory foraging in a free-living social insect

    Science.gov (United States)

    Christensen, Keri L.; Gallacher, Anthony P.; Martin, Lizzie; Tong, Desmond; Elgar, Mark A.

    2010-10-01

    The geometric framework model predicts that animal foraging decisions are influenced by their dietary history, with animals targeting a combination of essential nutrients through compensatory foraging. We provide experimental confirmation of nutrient-specific compensatory foraging in a natural, free-living population of social insects by supplementing their diet with sources of protein- or carbohydrate-rich food. Colonies of the ant Iridomyrmex suchieri were provided with feeders containing food rich in either carbohydrate or protein for 6 days, and were then provided with a feeder containing the same or different diet. The patterns of recruitment were consistent with the geometric framework: while feeders with a carbohydrate diet typically attracted more workers than did feeders with protein diet, the difference in recruitment between the two nutrients was smaller if the colonies had had prior access to carbohydrate than protein. Further, fewer ants visited feeders if the colony had had prior access to protein than to carbohydrates, suggesting that the larvae play a role in worker foraging behaviour.

  15. Improving Pervasive Positioning through Three-tier Cyber Foraging

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø; Kjærgaard, Mikkel Baun; Toftkjær, Thomas

    2011-01-01

    Cyber foraging is a pervasive computing technique where small, mobile devices offload resource intensive work to stronger, nearby surrogate computers in order to preserve energy and achieve better performance. The problem with relying only on local resources is, that the availability of such reso......Cyber foraging is a pervasive computing technique where small, mobile devices offload resource intensive work to stronger, nearby surrogate computers in order to preserve energy and achieve better performance. The problem with relying only on local resources is, that the availability...... of such resources may be scarce in many environments. In this paper we therefore argue that a third tier should be added when considering cyber foraging; namely cloud computing. By considering the local device, nearby surrogates, and the cloud when scheduling, the mobile device may be able to continue using remote...... the possible accuracy in many cases. In this paper we describe how a three tier cyber foraging approach can help improve the positioning capabilities of mobile devices. We demonstrate initial results for how such an approach applies to particle filtering-based GSM positioning....

  16. Home Range, Habitat Selection, and Foraging Rhythm in Mauritanian Spoonbills (

    NARCIS (Netherlands)

    El-Hacen, E.-H.M.; Overdijk, O.; Lok, T.; Olff, H.; Piersma, T.

    2013-01-01

    Mauritanian Spoonbills (Platalea leucorodia balsaci) only breed at Banc d'Arguin, Mauritania, West Africa. Their populations have declined; however, nothing is known about possible ecological factors involved, including their primary food and foraging habits. Home range sizes, habitat selection, and

  17. Evaluating Student Assessments: The Use of Optimal Foraging Theory

    Science.gov (United States)

    Whalley, W. Brian

    2016-01-01

    The concepts of optimal foraging theory and the marginal value theorem are used to investigate possible student behaviour in accruing marks in various forms of assessment. The ideas of predator energy consumption, handling and search times can be evaluated in terms of student behaviour and gaining marks or "attainment". These ideas can…

  18. The Role of Semantic Clustering in Optimal Memory Foraging

    Science.gov (United States)

    Montez, Priscilla; Thompson, Graham; Kello, Christopher T.

    2015-01-01

    Recent studies of semantic memory have investigated two theories of optimal search adopted from the animal foraging literature: Lévy flights and marginal value theorem. Each theory makes different simplifying assumptions and addresses different findings in search behaviors. In this study, an experiment is conducted to test whether clustering in…

  19. Calculating foraging area using gloal navigation satellite system (GNSS) technology

    Science.gov (United States)

    Adjusting stocking rate to changing forage conditions is a critical part of pro-active range management. In general stocking rate approaches tend to assume more optimal landscape use patterns than will actually occur. Today we can monitor spatio-temporal landscape use on a 24/7 basis using animals...

  20. Foraging behavior and virulence of some entomopathogenic nematodes

    Directory of Open Access Journals (Sweden)

    Manana A. Lortkipanidze

    2016-06-01

    Full Text Available At present the biological control as a pest control technology is becoming more desirable. Biological formulations on basis of entomopathogenic nematodes are one of the effective means for the protection of agricultural and forest plants from harmful insects. Nowadays, the use of entomopathogenic nematodes as biological control agents is a key component in IPM system. The foraging strategies of entomopathogenic nematodes (EPNs vary between species. This variation is consistent with use of different foraging strategies between ambush, cruise and intermediate to find their host insects. In order to ambush prey, some species of EPNs nictate, or raise their bodies of the soil surface so they are better poised to attach passing insects, other species adopt a cruising strategy and rarely nictate. Some species adopt an intermediate strategy between ambush and cruise. We compared in laboratory the foraging strategies of the entomopathogenic nematode species: Steinernema carpocapsae, Heterorhabditis bacteriophora and the recently described species Steinernema tbilisiensis and assessed their virulence against mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae. The tests showed that S. tbilisiensis adopts both foraging strategies.

  1. Optimal foraging, not biogenetic law, predicts spider orb web allometry

    Science.gov (United States)

    Gregorič, Matjaž; Kiesbüy, Heine C.; Quiñones Lebrón, Shakira G.; Rozman, Alenka; Agnarsson, Ingi; Kuntner, Matjaž

    2013-03-01

    The biogenetic law posits that the ontogeny of an organism recapitulates the pattern of evolutionary changes. Morphological evidence has offered some support for, but also considerable evidence against, the hypothesis. However, biogenetic law in behavior remains underexplored. As physical manifestation of behavior, spider webs offer an interesting model for the study of ontogenetic behavioral changes. In orb-weaving spiders, web symmetry often gets distorted through ontogeny, and these changes have been interpreted to reflect the biogenetic law. Here, we test the biogenetic law hypothesis against the alternative, the optimal foraging hypothesis, by studying the allometry in Leucauge venusta orb webs. These webs range in inclination from vertical through tilted to horizontal; biogenetic law predicts that allometry relates to ontogenetic stage, whereas optimal foraging predicts that allometry relates to gravity. Specifically, pronounced asymmetry should only be seen in vertical webs under optimal foraging theory. We show that, through ontogeny, vertical webs in L. venusta become more asymmetrical in contrast to tilted and horizontal webs. Biogenetic law thus cannot explain L. venusta web allometry, but our results instead support optimization of foraging area in response to spider size.

  2. At-Sea Associations in Foraging Little Penguins

    Science.gov (United States)

    Berlincourt, Maud; Arnould, John P. Y.

    2014-01-01

    Prey distribution, patch size, and the presence of conspecifics are important factors influencing a predator’s feeding tactics, including the decision to feed individually or socially. Little is known about group behaviour in seabirds as they spend most of their lives in the marine environment where it is difficult to observe their foraging activities. In this study, we report on at-sea foraging associations of little penguins (Eudyptula minor) during the breeding season. Individuals could be categorised as (1) not associating; (2) associating when departing from and/or returning to the colony; or (3) at sea when travelling, diving or performing synchronised dives. Out of 84 separate foraging tracks, 58 (69.0%) involved associations with conspecifics. Furthermore, in a total of 39 (46.4%), individuals were found to dive during association and in 32 (38.1%), individuals were found to exhibit synchronous diving. These behaviours suggest little penguins forage in groups, could synchronise their underwater movements and potentially cooperate to concentrate their small schooling prey. PMID:25119718

  3. Human memory retrieval as Lévy foraging

    Science.gov (United States)

    Rhodes, Theo; Turvey, Michael T.

    2007-11-01

    When people attempt to recall as many words as possible from a specific category (e.g., animal names) their retrievals occur sporadically over an extended temporal period. Retrievals decline as recall progresses, but short retrieval bursts can occur even after tens of minutes of performing the task. To date, efforts to gain insight into the nature of retrieval from this fundamental phenomenon of semantic memory have focused primarily upon the exponential growth rate of cumulative recall. Here we focus upon the time intervals between retrievals. We expected and found that, for each participant in our experiment, these intervals conformed to a Lévy distribution suggesting that the Lévy flight dynamics that characterize foraging behavior may also characterize retrieval from semantic memory. The closer the exponent on the inverse square power-law distribution of retrieval intervals approximated the optimal foraging value of 2, the more efficient was the retrieval. At an abstract dynamical level, foraging for particular foods in one's niche and searching for particular words in one's memory must be similar processes if particular foods and particular words are randomly and sparsely located in their respective spaces at sites that are not known a priori. We discuss whether Lévy dynamics imply that memory processes, like foraging, are optimized in an ecological way.

  4. At-sea associations in foraging little penguins.

    Directory of Open Access Journals (Sweden)

    Maud Berlincourt

    Full Text Available Prey distribution, patch size, and the presence of conspecifics are important factors influencing a predator's feeding tactics, including the decision to feed individually or socially. Little is known about group behaviour in seabirds as they spend most of their lives in the marine environment where it is difficult to observe their foraging activities. In this study, we report on at-sea foraging associations of little penguins (Eudyptula minor during the breeding season. Individuals could be categorised as (1 not associating; (2 associating when departing from and/or returning to the colony; or (3 at sea when travelling, diving or performing synchronised dives. Out of 84 separate foraging tracks, 58 (69.0% involved associations with conspecifics. Furthermore, in a total of 39 (46.4%, individuals were found to dive during association and in 32 (38.1%, individuals were found to exhibit synchronous diving. These behaviours suggest little penguins forage in groups, could synchronise their underwater movements and potentially cooperate to concentrate their small schooling prey.

  5. The bacterial communities associated with honey bee (Apis mellifera) foragers

    National Research Council Canada - National Science Library

    Corby-Harris, Vanessa; Maes, Patrick; Anderson, Kirk E

    2014-01-01

    ... balance of individuals and the hive. While many recent studies support the idea of a core microbiota in guts of younger in-hive bees, it is unknown whether this core is present in forager bees or the pollen they carry back to the hive...

  6. Urban foraging and the relational ecologies of belonging

    Science.gov (United States)

    Melissa R. Poe; Joyce LeCompte; Rebecca McLain; Patrick T. Hurley

    2014-01-01

    Through a discussion of urban foraging in Seattle, Washington, USA, we examine how people’s plant and mushroom harvesting practices in cities are linked to relationships with species, spaces, and ecologies. Bringing a relational approach to political ecology, we discuss the ways that these particular nature–society relationships are formed, legitimated, and mobilized...

  7. Honeybee economics: optimisation of foraging in a variable world.

    Science.gov (United States)

    Stabentheiner, Anton; Kovac, Helmut

    2016-06-20

    In honeybees fast and efficient exploitation of nectar and pollen sources is achieved by persistent endothermy throughout the foraging cycle, which means extremely high energy costs. The need for food promotes maximisation of the intake rate, and the high costs call for energetic optimisation. Experiments on how honeybees resolve this conflict have to consider that foraging takes place in a variable environment concerning microclimate and food quality and availability. Here we report, in simultaneous measurements of energy costs, gains, and intake rate and efficiency, how honeybee foragers manage this challenge in their highly variable environment. If possible, during unlimited sucrose flow, they follow an 'investment-guided' ('time is honey') economic strategy promising increased returns. They maximise net intake rate by investing both own heat production and solar heat to increase body temperature to a level which guarantees a high suction velocity. They switch to an 'economizing' ('save the honey') optimisation of energetic efficiency if the intake rate is restricted by the food source when an increased body temperature would not guarantee a high intake rate. With this flexible and graded change between economic strategies honeybees can do both maximise colony intake rate and optimise foraging efficiency in reaction to environmental variation.

  8. Nitrogen fertilization effects on sorghum forage yield and quality

    Science.gov (United States)

    The study objective was to determine the effect of nitrogen fertilization on yield and quality of photoperiod sensitive (PS) and non-PS forage sorghum, sorghum-sudangrass, and sudangrass compared to corn. This study was a randomized complete block design with treatments arranged in a 4 x 8 factorial...

  9. Potential energetic effects of mountain climbers on foraging grizzly bears

    Science.gov (United States)

    White, D.; Kendall, K.C.; Picton, H.D.

    1999-01-01

    Most studies of the effects of human disturbance on grizzly bears (Ursus arctos horribilis) have not quantified the energetic effects of such interactions. In this study, we characterized activity budgets of adult grizzly bears as they foraged on aggregations of adult army cutworm moths (Euxoa auxiliaris) in the alpine of Glacier National Park, Montana, during 1992, 1994, and 1995. We compared the activity budgets of climber-disturbed bears to those of undisturbed bears to estimate the energetic impact of climber disturbance. When bears detected climbers, they subsequently spent 53% less time foraging on moths, 52% more time moving within the foraging area, and 23% more time behaving aggressively, compared to when they were not disturbed. We estimated that grizzly bears could consume approximately 40,000 moths/day or 1,700 moths/hour. At 0.44 kcal/moth, disruption of moth feeding cost bears approximately 12 kcal/minute in addition to the energy expended in evasive maneuvers and defensive behaviors. To reduce both climber interruption of bear foraging and the potential for aggressive bear-human encounters, we recommend routing climbers around moth sites used by bears or limiting access to these sites during bear-use periods.

  10. Legume-Cereal Intercropping Improves Forage Yield, Quality and Degradability.

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    Jie Zhang

    Full Text Available Intercropping legume with cereal is an extensively applied planting pattern in crop cultivation. However, forage potential and the degradability of harvested mixtures from intercropping system remain unclear. To investigate the feasibility of applying an intercropping system as a forage supply source to ruminants, two consecutive experiments (experiments 1 and 2 involving a field cultivation trial and a subsequent in vivo degradable experiment were conducted to determine the forage production performance and the ruminally degradable characteristics of a harvested mixture from an alfalfa/corn-rye intercropping system. In experiment 1, the intercropping system was established by alternating alfalfa and corn or rye with a row ratio of 5:2. Dry matter (DM and nutrient yields were determined. In experiment 2, forages harvested from the different treatments were used as feedstuff to identify nutrient degradation kinetics and distribution of components between the rapidly degradable (a, potentially degradable (b and the degradation rate constant (c of 'b' fraction by in sacco method in Small-Tail Han wether Sheep. The intercropping system of alfalfa and corn-rye provided higher forage production performance with net increases of 9.52% and 34.81% in DM yield, 42.13% and 16.74% in crude protein (CP yield, 25.94% and 69.99% in degradable DM yield, and 16.96% and 5.50% in degradable CP yield than rotation and alfalfa sole cropping systems, respectively. In addition, the harvest mixture from intercropping system also had greater 'a' fraction, 'b' fraction, 'c' values, and effective degradability (E value of DM and CP than corn or rye hay harvested from rotation system. After 48-h exposure to rumen microbes, intercropping harvest materials were degraded to a higher extent than separately degraded crop stems from the sole system as indicated by visual microscopic examination with more tissues disappeared. Thus, the intercropping of alfalfa and corn

  11. Legume-Cereal Intercropping Improves Forage Yield, Quality and Degradability.

    Science.gov (United States)

    Zhang, Jie; Yin, Binjie; Xie, Yuhuai; Li, Jing; Yang, Zaibin; Zhang, Guiguo

    2015-01-01

    Intercropping legume with cereal is an extensively applied planting pattern in crop cultivation. However, forage potential and the degradability of harvested mixtures from intercropping system remain unclear. To investigate the feasibility of applying an intercropping system as a forage supply source to ruminants, two consecutive experiments (experiments 1 and 2) involving a field cultivation trial and a subsequent in vivo degradable experiment were conducted to determine the forage production performance and the ruminally degradable characteristics of a harvested mixture from an alfalfa/corn-rye intercropping system. In experiment 1, the intercropping system was established by alternating alfalfa and corn or rye with a row ratio of 5:2. Dry matter (DM) and nutrient yields were determined. In experiment 2, forages harvested from the different treatments were used as feedstuff to identify nutrient degradation kinetics and distribution of components between the rapidly degradable (a), potentially degradable (b) and the degradation rate constant (c) of 'b' fraction by in sacco method in Small-Tail Han wether Sheep. The intercropping system of alfalfa and corn-rye provided higher forage production performance with net increases of 9.52% and 34.81% in DM yield, 42.13% and 16.74% in crude protein (CP) yield, 25.94% and 69.99% in degradable DM yield, and 16.96% and 5.50% in degradable CP yield than rotation and alfalfa sole cropping systems, respectively. In addition, the harvest mixture from intercropping system also had greater 'a' fraction, 'b' fraction, 'c' values, and effective degradability (E value) of DM and CP than corn or rye hay harvested from rotation system. After 48-h exposure to rumen microbes, intercropping harvest materials were degraded to a higher extent than separately degraded crop stems from the sole system as indicated by visual microscopic examination with more tissues disappeared. Thus, the intercropping of alfalfa and corn-rye exhibited a greater

  12. Interactions with combined chemical cues inform harvester ant foragers' decisions to leave the nest in search of food.

    Science.gov (United States)

    Greene, Michael J; Pinter-Wollman, Noa; Gordon, Deborah M

    2013-01-01

    Social insect colonies operate without central control or any global assessment of what needs to be done by workers. Colony organization arises from the responses of individuals to local cues. Red harvester ants (Pogonomyrmex barbatus) regulate foraging using interactions between returning and outgoing foragers. The rate at which foragers return with seeds, a measure of food availability, sets the rate at which outgoing foragers leave the nest on foraging trips. We used mimics to test whether outgoing foragers inside the nest respond to the odor of food, oleic acid, the odor of the forager itself, cuticular hydrocarbons, or a combination of both with increased foraging activity. We compared foraging activity, the rate at which foragers passed a line on a trail, before and after the addition of mimics. The combination of both odors, those of food and of foragers, is required to stimulate foraging. The addition of blank mimics, mimics coated with food odor alone, or mimics coated with forager odor alone did not increase foraging activity. We compared the rates at which foragers inside the nest interacted with other ants, blank mimics, and mimics coated with a combination of food and forager odor. Foragers inside the nest interacted more with mimics coated with combined forager/seed odors than with blank mimics, and these interactions had the same effect as those with other foragers. Outgoing foragers inside the nest entrance are stimulated to leave the nest in search of food by interacting with foragers returning with seeds. By using the combined odors of forager cuticular hydrocarbons and of seeds, the colony captures precise information, on the timescale of seconds, about the current availability of food.

  13. Interactions with combined chemical cues inform harvester ant foragers' decisions to leave the nest in search of food.

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    Michael J Greene

    Full Text Available Social insect colonies operate without central control or any global assessment of what needs to be done by workers. Colony organization arises from the responses of individuals to local cues. Red harvester ants (Pogonomyrmex barbatus regulate foraging using interactions between returning and outgoing foragers. The rate at which foragers return with seeds, a measure of food availability, sets the rate at which outgoing foragers leave the nest on foraging trips. We used mimics to test whether outgoing foragers inside the nest respond to the odor of food, oleic acid, the odor of the forager itself, cuticular hydrocarbons, or a combination of both with increased foraging activity. We compared foraging activity, the rate at which foragers passed a line on a trail, before and after the addition of mimics. The combination of both odors, those of food and of foragers, is required to stimulate foraging. The addition of blank mimics, mimics coated with food odor alone, or mimics coated with forager odor alone did not increase foraging activity. We compared the rates at which foragers inside the nest interacted with other ants, blank mimics, and mimics coated with a combination of food and forager odor. Foragers inside the nest interacted more with mimics coated with combined forager/seed odors than with blank mimics, and these interactions had the same effect as those with other foragers. Outgoing foragers inside the nest entrance are stimulated to leave the nest in search of food by interacting with foragers returning with seeds. By using the combined odors of forager cuticular hydrocarbons and of seeds, the colony captures precise information, on the timescale of seconds, about the current availability of food.

  14. Foraging segregation of two congeneric diving seabird species breeding on St. George Island, Bering Sea

    Science.gov (United States)

    Kokubun, Nobuo; Yamamoto, Takashi; Sato, Nobuhiko; Watanuki, Yutaka; Will, Alexis; Kitaysky, Alexander S.; Takahashi, Akinori

    2016-04-01

    Subarctic environmental changes are expected to affect the foraging ecology of marine top predators, but the response to such changes may vary among species if they use food resources differently. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabird: common (Uria aalge: hereafter COMUs) and thick-billed (U. lomvia: hereafter TBMUs) murres breeding on St. George Island, located in the seasonal sea-ice region of the Bering Sea. We investigated their foraging trip and flight durations, diel patterns of dive depth, and underwater wing strokes, along with wing morphology and blood stable isotope signatures and stress hormones. Acceleration-temperature-depth loggers were attached to chick-guarding birds, and data were obtained from 7 COMUs and 12 TBMUs. Both species showed similar mean trip duration (13.2 h for COMUs and 10.5 h for TBMUs) and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime). During the daytime, the dive depths of COMUs had two peaks in shallow (18.1 m) and deep (74.2 m) depths, while those of TBMUs were 20.2 m and 59.7 m. COMUs showed more frequent wing strokes during the bottom phase of dives (1.90 s-1) than TBMUs (1.66 s-1). Fish occurred more frequently in the bill loads of COMUs (85 %) than those of TBMUs (56 %). The δ15N value of blood was significantly higher in COMUs (14.5 ‰) than in TBMUs (13.1 ‰). The relatively small wing area (0.053 m2) of COMUs compared to TBMUs (0.067 m2) may facilitate their increased agility while foraging and allow them to capture more mobile prey such as larger fishes that inhabit deeper depths. These differences in food resource use may lead to the differential responses of the two murre species to marine environmental changes in the Bering Sea.

  15. Genome-Wide Association Mapping and Genomic Selection for Alfalfa (Medicago sativa) Forage Quality Traits

    Science.gov (United States)

    Pecetti, Luciano; Brummer, E. Charles; Palmonari, Alberto; Tava, Aldo

    2017-01-01

    Genetic progress for forage quality has been poor in alfalfa (Medicago sativa L.), the most-grown forage legume worldwide. This study aimed at exploring opportunities for marker-assisted selection (MAS) and genomic selection of forage quality traits based on breeding values of parent plants. Some 154 genotypes from a broadly-based reference population were genotyped by genotyping-by-sequencing (GBS), and phenotyped for leaf-to-stem ratio, leaf and stem contents of protein, neutral detergent fiber (NDF) and acid detergent lignin (ADL), and leaf and stem NDF digestibility after 24 hours (NDFD), of their dense-planted half-sib progenies in three growing conditions (summer harvest, full irrigation; summer harvest, suspended irrigation; autumn harvest). Trait-marker analyses were performed on progeny values averaged over conditions, owing to modest germplasm × condition interaction. Genomic selection exploited 11,450 polymorphic SNP markers, whereas a subset of 8,494 M. truncatula-aligned markers were used for a genome-wide association study (GWAS). GWAS confirmed the polygenic control of quality traits and, in agreement with phenotypic correlations, indicated substantially different genetic control of a given trait in stems and leaves. It detected several SNPs in different annotated genes that were highly linked to stem protein content. Also, it identified a small genomic region on chromosome 8 with high concentration of annotated genes associated with leaf ADL, including one gene probably involved in the lignin pathway. Three genomic selection models, i.e., Ridge-regression BLUP, Bayes B and Bayesian Lasso, displayed similar prediction accuracy, whereas SVR-lin was less accurate. Accuracy values were moderate (0.3–0.4) for stem NDFD and leaf protein content, modest for leaf ADL and NDFD, and low to very low for the other traits. Along with previous results for the same germplasm set, this study indicates that GBS data can be exploited to improve both quality traits

  16. Foraging flight distances of wintering ducks and geese: a review

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    William P. Johnson

    2014-12-01

    Full Text Available The distance covered by foraging animals, especially those that radiate from a central area when foraging, may affect ecosystem, community, and population dynamics, and has conservation and landscape planning implications for multiple taxa, including migratory waterfowl. Migrating and wintering waterfowl make regular foraging flights between roosting and feeding areas that can greatly impact energetic resources within the foraging zone near roost sites. We reviewed published studies and gray literature for one-way foraging flight distances (FFDs of migrating and wintering dabbling ducks and geese. Thirty reviewed studies reported FFDs and several reported values for multiple species or locations. We obtained FFD values for migration (n = 7 and winter (n = 70. We evaluated the effects of body mass, guild, i.e., dabbling duck or goose, and location, i.e., Nearctic or Palearctic, on FFDs. We used the second-order Akaike's Information Criterion for model selection. We found support for effects of location and guild on FFDs. FFDs of waterfowl wintering in the Nearctic (7.4 ± 6.7 km, mean ± SD; n = 39 values were longer than in the Palearctic (4.2 ± 3.2 km; n = 31 values. The FFDs of geese (7.8 ± 7.2 km, mean ± SD; n = 24 values were longer than FFDs of dabbling ducks (5.1 ± 4.4 km, mean ± SD; n = 46 values. We found mixed evidence that distance flown from the roost changed, i.e., increased or decreased, seasonally. Our results can be used to refine estimates of energetic carrying capacity around roosts and in biological and landscape planning efforts.

  17. Valuation of pollinator forage services provided by Eucalyptus cladocalyx.

    Science.gov (United States)

    de Lange, Willem J; Veldtman, Ruan; Allsopp, Mike H

    2013-08-15

    We assess the monetary value of forage provisioning services for honeybees as provided by an alien tree species in the Western Cape province of South Africa. Although Eucalyptus cladocalyx is not an officially declared invader, it is cleared on a regular basis along with other invasive Eucalyptus species such as Eucalyptus camaldulensis, and Eucalyptus conferruminata (which have been prioritised for eradication in South Africa). We present some of the trade-offs associated with the clearing of E. cladocalyx by means of a practical example that illustrates a situation where the benefits of the species to certain stakeholders could support the containment of the species in demarcated areas, while allowing clearing outside such areas. Given the absence of market prices for such forage provisioning services, the replacement cost is used to present the value of the loss in forage as provided by E. cladocalyx if the alien tree species is cleared along with invasive alien tree species. Two replacement scenarios formed the basis for our calculations. The first scenario was an artificial diet as replacement for the forage provisioning service, which yielded a direct cost estimate of US$7.5 m per year. The second was based on a Fynbos cultivation/restoration initiative aimed at substituting the forage provisioning service of E. cladocalyx, which yielded a direct cost of US$20.2 m per year. These figures provide estimates of the potential additional cost burden on the beekeeping industry if E. cladocalyx is completely eradicated from the Western Cape. The cost estimates should be balanced against the negative impacts of E. cladocalyx on ecosystem services in order to make an informed decision with regard to appropriate management strategies for this species. The findings therefore serve as useful inputs to balance trade-offs for alien species that are considered as beneficial to some, but harmful to other.

  18. Foraging fidelity as a recipe for a long life: foraging strategy and longevity in male Southern Elephant Seals.

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    Matthieu Authier

    Full Text Available Identifying individual factors affecting life-span has long been of interest for biologists and demographers: how do some individuals manage to dodge the forces of mortality when the vast majority does not? Answering this question is not straightforward, partly because of the arduous task of accurately estimating longevity in wild animals, and of the statistical difficulties in correlating time-varying ecological covariables with a single number (time-to-event. Here we investigated the relationship between foraging strategy and life-span in an elusive and large marine predator: the Southern Elephant Seal (Mirounga leonina. Using teeth recovered from dead males on îles Kerguelen, Southern Ocean, we first aged specimens. Then we used stable isotopic measurements of carbon (δ13C in dentin to study the effect of foraging location on individual life-span. Using a joint change-point/survival modelling approach which enabled us to describe the ontogenetic trajectory of foraging, we unveiled how a stable foraging strategy developed early in life positively covaried with longevity in male Southern Elephant Seals. Coupled with an appropriate statistical analysis, stable isotopes have the potential to tackle ecological questions of long standing interest but whose answer has been hampered by logistic constraints.

  19. Effects of harvest date, wilting and inoculation on yield and forage quality of ensiling safflower (Carthamus tinctorius L.) biomass.

    Science.gov (United States)

    Cazzato, Eugenio; Laudadio, Vito; Corleto, Antonio; Tufarelli, Vincenzo

    2011-09-01

    Safflower (Carthamus tinctorius L.), usually grown as a source of oil crop, can be used as fodder either for hay or ensiling purposes, particularly in semi-arid regions. A 2-year trial was conducted in southern Italy to evaluate the production and forage quality of safflower biomass cv. Centennial, harvested at three different stages: 1, at complete appearance of primary buds (PB); 2, at complete appearance of secondary and tertiary buds (STB); and 3, at 25% of flowering stage (FS). For each stage of growth, 50% of the biomass was ensiled in 4 L glass jars without and with inoculation (Lactobacillus plantarum, LAB), and the other 50% was field wilted for 24 h before ensiling. Dry matter (DM) content and yield (DMY), pH, buffering capacity (BC) and water soluble carbohydrates (WSC) were determined on fresh forage. On safflower silages were also evaluated ammonia-N, crude protein (CP), fibre fractions, fat, lactic and acetic acids, Ca and P, and gas losses. DMY ranged from 4.5 t ha(-1) (PB harvesting) to 11.6 t ha(-1) (FS harvesting). DM content varied from 129 g kg(-1) (PB not wilted) to 630 g kg(-1) (FS wilted). The WSC in forage before ensiling with not wilting ranged from 128 (PB stage) to 105 and 100 g kg(-1) DM at STB and FS stages, respectively. The wilted safflower forage showed a lower WSC compared to wilted forage. The high sugar substrate allowed lactic acid fermentation and a good conservation quality in all the harvesting stages. Silages quality was strongly influenced by the treatment performed. Wilting practice increased DM, pH and NDF contents but reduced lactic acid, acetic acid and NH(3) -N values. Inoculation reduced DM, pH and NDF contents, but increased lactic and acetic acids, CP and ash. As result, wilting the forage for 1 day was very effective in the early harvesting stage because this practice significantly increased DM, reducing on the same time the intensive fermentation and proteolysis processes of silage. When harvesting is performed at

  20. Foraging strategy quick response to temperature of Messor barbarus (Hymenoptera: Formicidae) in Mediterranean environments.

    Science.gov (United States)

    Doblas-Miranda, Enrique; Reyes-López, Joaquín

    2008-08-01

    Animals principally forage to try to maximize energy intake per unit of feeding time, developing different foraging strategies. Temperature effects on foraging have been observed in diverse ant species; these effects are limited to the duration of foraging or the number of foragers involved. The harvester ant Messor barbarus L. 1767 has a specialized foraging strategy that consists in the formation of worker trails. Because of the high permeability of their body integument, we presume that the length, shape, and type of foraging trails of M. barbarus must be affected by temperature conditions. From mid-June to mid-August 1999, we tested the effect on these trail characteristics in a Mediterranean forest. We found that thermal stress force ants to use a foraging pattern based on the variation of the workers trail structure. Ants exploit earlier well-known sources using long physical trails, but as temperatures increases throughout the morning, foragers reduce the length of the foraging column gradually, looking for alternative food sources in nonphysical trails. This study shows that animal forage can be highly adaptable and versatile in environments with high daily variations.

  1. Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard.

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    Maximilian Drakeley

    Full Text Available When foraging, animals can maximize their fitness if they are able to tailor their foraging decisions to current environmental conditions. When making foraging decisions, individuals need to assess the benefits of foraging while accounting for the potential risks of being captured by a predator. However, whether and how different factors interact to shape these decisions is not yet well understood, especially in individual foragers. Here we present a standardized set of manipulative field experiments in the form of foraging assays in the tropical lizard Anolis cristatellus in Puerto Rico. We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines the outcome of foraging decisions. In Experiment 1, anoles foraged faster when food was scarce and other conspecifics were present near the feeding tray, while they took longer to feed when food was abundant and when no conspecifics were present. These results suggest that foraging decisions in anoles are the result of a complex process in which individuals assess predation risk by using information from conspecific individuals while taking into account food abundance. In Experiment 2, a simulated increase in predation risk (i.e., distance to the feeding tray confirmed the relevance of risk perception by showing that the use of available perches is strongly correlated with the latency to feed. We found Puerto Rican crested anoles integrate instantaneous ecological information about food abundance, conspecific activity and predation risk, and adjust their foraging behavior accordingly.

  2. Colony variation in the collective regulation of foraging by harvester ants

    Science.gov (United States)

    Guetz, Adam; Greene, Michael J.; Holmes, Susan

    2011-01-01

    This study investigates variation in collective behavior in a natural population of colonies of the harvester ant, Pogonomyrmex barbatus. Harvester ant colonies regulate foraging activity to adjust to current food availability; the rate at which inactive foragers leave the nest on the next trip depends on the rate at which successful foragers return with food. This study investigates differences among colonies in foraging activity and how these differences are associated with variation among colonies in the regulation of foraging. Colonies differ in the baseline rate at which patrollers leave the nest, without stimulation from returning ants. This baseline rate predicts a colony's foraging activity, suggesting there is a colony-specific activity level that influences how quickly any ant leaves the nest. When a colony's foraging activity is high, the colony is more likely to regulate foraging. Moreover, colonies differ in the propensity to adjust the rate of outgoing foragers to the rate of forager return. Naturally occurring variation in the regulation of foraging may lead to variation in colony survival and reproductive success. PMID:22479133

  3. Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard.

    Science.gov (United States)

    Drakeley, Maximilian; Lapiedra, Oriol; Kolbe, Jason J

    2015-01-01

    When foraging, animals can maximize their fitness if they are able to tailor their foraging decisions to current environmental conditions. When making foraging decisions, individuals need to assess the benefits of foraging while accounting for the potential risks of being captured by a predator. However, whether and how different factors interact to shape these decisions is not yet well understood, especially in individual foragers. Here we present a standardized set of manipulative field experiments in the form of foraging assays in the tropical lizard Anolis cristatellus in Puerto Rico. We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines the outcome of foraging decisions. In Experiment 1, anoles foraged faster when food was scarce and other conspecifics were present near the feeding tray, while they took longer to feed when food was abundant and when no conspecifics were present. These results suggest that foraging decisions in anoles are the result of a complex process in which individuals assess predation risk by using information from conspecific individuals while taking into account food abundance. In Experiment 2, a simulated increase in predation risk (i.e., distance to the feeding tray) confirmed the relevance of risk perception by showing that the use of available perches is strongly correlated with the latency to feed. We found Puerto Rican crested anoles integrate instantaneous ecological information about food abundance, conspecific activity and predation risk, and adjust their foraging behavior accordingly.

  4. Utilization of Swamp Forages from South Kalimantan on Local Goat Performances

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    T. Rostini

    2014-04-01

    Full Text Available Forages in swamp area consist of grass and legumes that have good productivity and nutrient quality. This research was aimed to evaluate the potency of swamp forage on digestibility and performance of goats. There were 24 local male goats aged 10-12 months with initial body weight of 13.10±1.55 kg, allocated into 6 treatments. Those were control (R0: 60% grass and 40% legumes; (R1: 60% swamp forages and 40% concentrate; (R2: 100% swamp forages; (R3: 100% swamp forage hay; (R4: 100% swamp forage silage; (R5: 100% haylage swamp forages. Results showed that silage treatment significantly increased (P<0.05 consumption and digestibility. Swamp forages could be utilized well by preservation (silage, hay, and haylage. Ensilage of swamp forages increased protein content from 13.72% to 14.02%, protein intake (74.62 g/d, dry matter intake (532.11 g/d, nitrogen free extract intake (257.39 g/d, with total body weight gain (3.5 kg in eight weeks and average daily gain (62.60 g/d. It is concluded that ensilage of swamp forages (R4 is very potential to be utilized as forage source for ruminants such as goats.

  5. Colony variation in the collective regulation of foraging by harvester ants.

    Science.gov (United States)

    Gordon, Deborah M; Guetz, Adam; Greene, Michael J; Holmes, Susan

    2011-03-01

    This study investigates variation in collective behavior in a natural population of colonies of the harvester ant, Pogonomyrmex barbatus. Harvester ant colonies regulate foraging activity to adjust to current food availability; the rate at which inactive foragers leave the nest on the next trip depends on the rate at which successful foragers return with food. This study investigates differences among colonies in foraging activity and how these differences are associated with variation among colonies in the regulation of foraging. Colonies differ in the baseline rate at which patrollers leave the nest, without stimulation from returning ants. This baseline rate predicts a colony's foraging activity, suggesting there is a colony-specific activity level that influences how quickly any ant leaves the nest. When a colony's foraging activity is high, the colony is more likely to regulate foraging. Moreover, colonies differ in the propensity to adjust the rate of outgoing foragers to the rate of forager return. Naturally occurring variation in the regulation of foraging may lead to variation in colony survival and reproductive success.

  6. Grading Index(GI)∶A New Integrated Technique for Evaluation of Forage Quality

    Institute of Scientific and Technical Information of China (English)

    HU Hong-lian; GAO Min; LU De-xun

    2011-01-01

    IntroductionForage quality can be defined as the extent to which forage has the potential to produce a desired animal response or level of performance,for example,daily gain or milk production.Due to forage quality is a function of both animal and plant factors.It is difficult and complex to completely evaluate forage quality.Recently,an new integrated index,Grading index (GI),was proposed by Chinese scholar Lu Dexun.Grading index (GI) method has been appraised officially as the national standard of forage quality evaluation in China,which was implemented in 2009.On basis of briefly overview the development of forage quality evaluation technology,this paper is to emphasize on introducing forage grading index and its application in dairy cattle feeding.

  7. Fearful foragers: honey bees tune colony and individual foraging to multi-predator presence and food quality.

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    Ken Tan

    Full Text Available Fear can have strong ecosystem effects by giving predators a role disproportionate to their actual kill rates. In bees, fear is shown through foragers avoiding dangerous food sites, thereby reducing the fitness of pollinated plants. However, it remains unclear how fear affects pollinators in a complex natural scenario involving multiple predator species and different patch qualities. We studied hornets, Vespa velutina (smaller and V. tropica (bigger preying upon the Asian honey bee, Apis cerana in China. Hornets hunted bees on flowers and were attacked by bee colonies. Bees treated the bigger hornet species (which is 4 fold more massive as more dangerous. It received 4.5 fold more attackers than the smaller hornet species. We tested bee responses to a three-feeder array with different hornet species and varying resource qualities. When all feeders offered 30% sucrose solution (w/w, colony foraging allocation, individual visits, and individual patch residence times were reduced according to the degree of danger. Predator presence reduced foraging visits by 55-79% and residence times by 17-33%. When feeders offered different reward levels (15%, 30%, or 45% sucrose, colony and individual foraging favored higher sugar concentrations. However, when balancing food quality against multiple threats (sweeter food corresponding to higher danger, colonies exhibited greater fear than individuals. Colonies decreased foraging at low and high danger patches. Individuals exhibited less fear and only decreased visits to the high danger patch. Contrasting individual with emergent colony-level effects of fear can thus illuminate how predators shape pollination by social bees.

  8. Fearful foragers: honey bees tune colony and individual foraging to multi-predator presence and food quality.

    Science.gov (United States)

    Tan, Ken; Hu, Zongwen; Chen, Weiwen; Wang, Zhengwei; Wang, Yuchong; Nieh, James C

    2013-01-01

    Fear can have strong ecosystem effects by giving predators a role disproportionate to their actual kill rates. In bees, fear is shown through foragers avoiding dangerous food sites, thereby reducing the fitness of pollinated plants. However, it remains unclear how fear affects pollinators in a complex natural scenario involving multiple predator species and different patch qualities. We studied hornets, Vespa velutina (smaller) and V. tropica (bigger) preying upon the Asian honey bee, Apis cerana in China. Hornets hunted bees on flowers and were attacked by bee colonies. Bees treated the bigger hornet species (which is 4 fold more massive) as more dangerous. It received 4.5 fold more attackers than the smaller hornet species. We tested bee responses to a three-feeder array with different hornet species and varying resource qualities. When all feeders offered 30% sucrose solution (w/w), colony foraging allocation, individual visits, and individual patch residence times were reduced according to the degree of danger. Predator presence reduced foraging visits by 55-79% and residence times by 17-33%. When feeders offered different reward levels (15%, 30%, or 45% sucrose), colony and individual foraging favored higher sugar concentrations. However, when balancing food quality against multiple threats (sweeter food corresponding to higher danger), colonies exhibited greater fear than individuals. Colonies decreased foraging at low and high danger patches. Individuals exhibited less fear and only decreased visits to the high danger patch. Contrasting individual with emergent colony-level effects of fear can thus illuminate how predators shape pollination by social bees.

  9. Factores que afectan la germinación de Justicia squarrosa Griseb, forrajera nativa de la región chaqueña de la Argentina Factors affecting germination in Justicia squarrosa Griseb, a native forage species of the Chaco region of Argentina

    Directory of Open Access Journals (Sweden)

    M. Zalazar

    2009-06-01

    Full Text Available Justicia squarrosa es una especie forrajera presente en diferentes comunidades naturales del Chaco Árido argentino en donde constituye un importante componente en la dieta del ganado en épocas de escasez de agua. El objetivo del presente trabajo fue estudiar los factores que afectan la germinación de J. squarrosa. Se tuvieron en cuenta diferentes regímenes de temperatura, calidades de luz y potenciales hídricos; además, se evaluó la capacidad de germinación de sus semillas en el tiempo. La germinación de las semillas de J. squarrosa estuvo condicionada por factores como la temperatura y el estrés hídrico. Los mayores porcentajes de germinación se obtuvieron a 25/15 ºC tanto en luz como en oscuridad permanente. Por debajo de -0,2 MPa la germinación disminuyó significativamente. Las semillas de J. squarrosa fueron indiferentes a los tratamientos de luz. Luego de 48 meses se observó un alto porcentaje de germinación de las semillas de la especie. Los resultados obtenidos proporcionan información valiosa que ayudará a establecer estrategias de domesticación y propagación de la especie.Justicia squarrosa is a forage species that lives in different natural communities in Chaco Arido, where it is an important component of cattle diet in unfavourable drought periods. The aim of this work was to study the factors affecting seed germination in J. squarrosa. Different temperature regimes, light quality and water potential were considered. Seed germination capacity along time was also evaluated. Justicia squarrosa seed germination was conditioned by factors such as temperature and water potential. The highest germination percent was found at 25/15 ºC, both in light and dark. Seed germination decreased significantly below -0.2 MPa. Justicia squarrosa seeds did not respond to light treatments. After 48 months the percentage of seed germination was high. The results found in this article provide valuable information that will help to

  10. Marine Forage Fishes in Puget Sound

    Science.gov (United States)

    2007-03-01

    of the intertidal zone. Across the Puget Sound region, the native eelgrass Zostera marina is of primary importance as a herring spawning... Aquaculture Standard aquaculture practices may have profound effects on the benthic ecology of Washington state’s tidelands and the conservation...authority over aquaculture activities that occur in intertidal areas of state waters. The Washington Department of Natural Resources (WDNR) has authority

  11. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies.

    Science.gov (United States)

    Ellis, Samuel; Robinson, Elva J H

    2015-01-01

    A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas.

  12. High Dynamic Range Color Image Enhancement Using Fuzzy Logic and Bacterial Foraging

    Directory of Open Access Journals (Sweden)

    Om Prakash Verma

    2011-09-01

    Full Text Available High dynamic range images contain both the underexposed and the overexposed regions. The enhancement of the underexposed and the overexposed regions is the main concern of this paper. Two new transformation functions are proposed to modify the fuzzy membership values of under and the overexposed regions of an image respectively.For the overexposed regions, a rectangular hyperbolic function is used while for the underexposed regions, an S-function is applied. The shape and range of these functions can be controlled by the parameters involved, which are optimized using the bacterial foraging optimization algorithm so as to obtain the enhanced image. The hue, saturation, and intensity (HSV color space is employed for the purpose of enhancement, where the hue component is preserved to keep the original color composition intact. This approach is applicable to a degraded image of mixed type. On comparison, the proposed transforms yield better results than the existing transformation functions17 for both the underexposed and the overexposed regions.Defence Science Journal, 2011, 61(5, pp.462-472, DOI:http://dx.doi.org/10.14429/dsj.61.1184

  13. Division of foraging labor in the bumble bee, Bombus impatiens : effect of removing pollen specialists and colony adoption

    OpenAIRE

    Hagbery, Jessica

    2011-01-01

    Foraging specialization plays an important role in the ability of social Hymenoptera to efficiently allocate labor and adapt to environmental changes. However, relatively little is known about whether bumble bees, important social pollinators, can flexibly allocate their foraging. I removed pollen specialists at different stages in the life of a Bombus impatiens colony and recorded the pollen and nectar foraging of every forager on each foraging trip over the lifetimes of five established col...

  14. Social learning of an associative foraging task in zebrafish

    Science.gov (United States)

    Zala, Sarah M.; Määttänen, Ilmari

    2013-05-01

    The zebrafish ( Danio rerio) is increasingly becoming an important model species for studies on the genetic and neural mechanisms controlling behaviour and cognition. Here, we utilized a conditioned place preference (CPP) paradigm to study social learning in zebrafish. We tested whether social interactions with conditioned demonstrators enhance the ability of focal naïve individuals to learn an associative foraging task. We found that the presence of conditioned demonstrators improved focal fish foraging behaviour through the process of social transmission, whereas the presence of inexperienced demonstrators interfered with the learning of the control focal fish. Our results indicate that zebrafish use social learning for finding food and that this CPP paradigm is an efficient assay to study social learning and memory in zebrafish.

  15. Forage as a primary source of mycotoxins in animal diets.

    Science.gov (United States)

    Skládanka, Jiří; Nedělník, Jan; Adam, Vojtěch; Doležal, Petr; Moravcová, Hana; Dohnal, Vlastimil

    2011-01-01

    The issue of moulds and, thus, contamination with mycotoxins is very topical, particularly in connexion with forages from grass stands used at the end of the growing season. Deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUM) and aflatoxins (AFL) are among the most common mycotoxins. The aim of the paper was to determine concentrations of mycotoxins in selected grasses (Lolium perenne, Festulolium pabulare, Festulolium braunii) and their mixtures with Festuca rubra an/or Poa pratensis during the growing season as a marker of grass safety, which was assessed according to content of the aforementioned mycotoxins. During the growing season grass forage was contaminated with mycotoxins, most of all by DON and ZEA. The contents of AFL and FUM were zero or below the limit of quantification. Moreover, the level of the occurrence of mould was quantified as ergosterol content, which was higher at the specific date of cut. All results were statistically processed and significant changes were discussed.

  16. Do bigger bats need more time to forage?

    Directory of Open Access Journals (Sweden)

    CEL. Esbérard

    Full Text Available We test the hypothesis is that bats using the same area and at the same time would be using similar preys, but they would have different foraging times due to specific differences in biomass. A total of 730 captures was analyzed 13 species of Vespertilionidae and Molossidae bats netted over a small dam in southeastern Brazil from 1993 and 1999. The relationship between the average time of captures and the biomass of the species of Vespertilinidae and Molossidae most frequent (captures > 4 was positive and significant (r = 0.83, p = 0.022, N = 7. Two lines are discussed to answer the longer foraging time for bigger bats: 1 larger insectivorous bats don't consume proportionally larger preys and 2 larger insects are less available.

  17. PCNN document segmentation method based on bacterial foraging optimization algorithm

    Science.gov (United States)

    Liao, Yanping; Zhang, Peng; Guo, Qiang; Wan, Jian

    2014-04-01

    Pulse Coupled Neural Network(PCNN) is widely used in the field of image processing, but it is a difficult task to define the relative parameters properly in the research of the applications of PCNN. So far the determination of parameters of its model needs a lot of experiments. To deal with the above problem, a document segmentation based on the improved PCNN is proposed. It uses the maximum entropy function as the fitness function of bacterial foraging optimization algorithm, adopts bacterial foraging optimization algorithm to search the optimal parameters, and eliminates the trouble of manually set the experiment parameters. Experimental results show that the proposed algorithm can effectively complete document segmentation. And result of the segmentation is better than the contrast algorithms.

  18. Evolution of sustained foraging in 3D environments with physics

    CERN Document Server

    Chaumont, Nicolas

    2011-01-01

    Artificially evolving foraging behavior in simulated legged animals has proved to be a notoriously difficult task. Here, we co-evolve the morphology and controller for virtual organisms in a three-dimensional physically realistic environment to produce goal-directed legged locomotion. We show that following and reaching multiple food sources can evolve de novo, by evaluating each organism on multiple food sources placed on a basic pattern that is gradually randomized across generations. We devised a strategy of evolutionary "staging", where the best organism from a set of evolutionary experiments using a particular fitness function is used to seed a new set, with a fitness function that is progressively altered to better challenge organisms as evolution improves them. We find that an organism's efficiency at reaching the first food source does not predict its ability at finding subsequent ones because foraging efficiency crucially depends on the position of the last food source reached, an effect illustrated ...

  19. Linking animal population dynamics to alterations in foraging behaviour

    DEFF Research Database (Denmark)

    Nabe-Nielsen, Jacob; Sibly, Richard; Tougaard, Jakob

    Background/Question/Methods The survival of animal populations is strongly influenced by the individuals’ ability to forage efficiently, yet there are few studies of how populations respond when disturbances cause animals to deviate from their natural foraging behavior. Animals that respond...... was not jeopardized even when disturbances were simulated to have a relatively large and persistent effect on the behavior of individual animals. Porpoises were simulated to move away from noisy objects, preventing them from returning to the known food patches in that area. This resulted in decreasing energy reserves...... that are increasingly exposed to noise from ships, wind turbines, etc. In the present study we investigate how the dynamics of the harbor porpoise population (Phocoena phocoena) in the inner Danish waters is influenced by disturbances using an agent- based simulation model. In the model animal movement, and hence...

  20. Extrafloral nectar content alters foraging preferences of a predatory ant.

    Science.gov (United States)

    Wilder, Shawn M; Eubanks, Micky D

    2010-04-23

    We tested whether the carbohydrate and amino acid content of extrafloral nectar affected prey choice by a predatory ant. Fire ants, Solenopsis invicta, were provided with artificial nectar that varied in the presence of carbohydrates and amino acids and were then provided with two prey items that differed in nutritional content, female and male crickets. Colonies of fire ants provided with carbohydrate supplements consumed less of the female crickets and frequently did not consume the high-lipid ovaries of female crickets. Colonies of fire ants provided with amino acid supplements consumed less of the male crickets. While a number of studies have shown that the presence of extrafloral nectar or honeydew can affect ant foraging activity, these results suggest that the nutritional composition of extrafloral nectar is also important and can affect subsequent prey choice by predatory ants. Our results suggest that, by altering the composition of extrafloral nectar, plants could manipulate the prey preferences of ants foraging on them.

  1. A mathematical and experimental study of ant foraging trail dynamics.

    Science.gov (United States)

    Johnson, Katie; Rossi, Louis F

    2006-07-21

    In this article, we present a mathematical model coupled to an experimental study of ant foraging trails. Our laboratory experiments on Tetramorium caespitum do not find a strong relationship between ant densities and velocities, a common assumption in traffic modeling. Rather, we find that higher order effects play a major role in observed behavior, and our model reflects this by including inertial terms in the evolution equation. A linearization of the resulting system yields left- and right-moving waves, in agreement with laboratory measurements. The linearized system depends upon Froude numbers reflecting a ratio of the energy stored in the foraging trail to the kinetic energy of the ants. The model predicts and the measurements support the existence of two distinct phase velocities.

  2. Protecting rain forests and forager's rights using LANDSAT imagery

    Science.gov (United States)

    Wilkie, David S.

    1991-01-01

    Creating rain forest reserves is vital given the global decline in biodiversity. Yet, the plants and animals that will be protected from untrammeled commercial exploitation within such reserves constitute essential resources for indigenous foragers and farmers. Balancing the needs of local subsistence level populations with the goals of national and international conservation agencies requires a thorough understanding of the mutual impacts that arise from the interaction of park and people. In the Ituri forest of Zaire, LANDSAT TM image analysis and GPS ground truth data were used to locate human settlements so that boundaries of the proposed Okapi Reserve could be chosen to minimize its impact on the subsistence practices of the local foragers and farmers. Using satellite imagery in conjunction with cultural information should help to ensure traditional resource exploitation rights of indigenous peoples whilst simultaneously protecting the largest contiguous area of undisturbed forest.

  3. Protecting rain forests and forager's rights using LANDSAT imagery

    Science.gov (United States)

    Wilkie, David S.

    1991-01-01

    Creating rain forest reserves is vital given the global decline in biodiversity. Yet, the plants and animals that will be protected from untrammeled commercial exploitation within such reserves constitute essential resources for indigenous foragers and farmers. Balancing the needs of local subsistence level populations with the goals of national and international conservation agencies requires a thorough understanding of the mutual impacts that arise from the interaction of park and people. In the Ituri forest of Zaire, LANDSAT TM image analysis and GPS ground truth data were used to locate human settlements so that boundaries of the proposed Okapi Reserve could be chosen to minimize its impact on the subsistence practices of the local foragers and farmers. Using satellite imagery in conjunction with cultural information should help to ensure traditional resource exploitation rights of indigenous peoples whilst simultaneously protecting the largest contiguous area of undisturbed forest.

  4. Wild Bee Community Composition and Foraging Behaviour in Commercial Strawberries

    DEFF Research Database (Denmark)

    Ahrenfeldt, Erica Juel

    Denmark and under widespread cultivation in the rest of the world. A review study (IV) of the literature on wild bees and their pollination services in flowering crops make up the final part of the thesis. The review study aimed to assess how wild bees may respond to landscape parameters based......The agricultural value of wild bees is their contribution to crop pollination and studies have shown that abundance, species richness and functional diversity of bees can increase yield and quality of flowering crops. Wild bee pollination services thus carry great value regardless of the presence...... to a landscape with fragmented resources may already have taken place in the areas sampled. Paper I and III showed that limitations on foraging ability and different foraging needs can drive different visitation patterns in a flowering crop. The review study (IV) found variation in results from different studies...

  5. Social learning of an associative foraging task in zebrafish.

    Science.gov (United States)

    Zala, Sarah M; Määttänen, Ilmari

    2013-05-01

    The zebrafish (Danio rerio) is increasingly becoming an important model species for studies on the genetic and neural mechanisms controlling behaviour and cognition. Here, we utilized a conditioned place preference (CPP) paradigm to study social learning in zebrafish. We tested whether social interactions with conditioned demonstrators enhance the ability of focal naïve individuals to learn an associative foraging task. We found that the presence of conditioned demonstrators improved focal fish foraging behaviour through the process of social transmission, whereas the presence of inexperienced demonstrators interfered with the learning of the control focal fish. Our results indicate that zebrafish use social learning for finding food and that this CPP paradigm is an efficient assay to study social learning and memory in zebrafish.

  6. Chemical compounds of the foraging recruitment pheromone in bumblebees

    Science.gov (United States)

    Granero, Angeles Mena; Sanz, José M. Guerra; Gonzalez, Francisco J. Egea; Vidal, José L. Martinez; Dornhaus, Anna; Ghani, Junaid; Serrano, Ana Roldán; Chittka, Lars

    2005-08-01

    When the frenzied and irregular food-recruitment dances of bumblebees were first discovered, it was thought that they might represent an evolutionary prototype to the honeybee waggle dance. It later emerged that the primary function of the bumblebee dance was the distribution of an alerting pheromone. Here, we identify the chemical compounds of the bumblebee recruitment pheromone and their behaviour effects. The presence of two monoterpenes and one sesquiterpene (eucalyptol, ocimene and farnesol) in the nest airspace and in the tergal glands increases strongly during foraging. Of these, eucalyptol has the strongest recruitment effect when a bee nest is experimentally exposed to it. Since honeybees use terpenes for marking food sources rather than recruiting foragers inside the nest, this suggests independent evolutionary roots of food recruitment in these two groups of bees.

  7. Responses of late-lactation cows to forage substitutes in low-forage diets supplemented with by-products.

    Science.gov (United States)

    Hall, M B; Chase, L E

    2014-05-01

    In response to drought-induced forage shortages along with increased corn and soy prices, this study was conducted to evaluate lactation responses of dairy cows to lower-forage diets supplemented with forage substitutes. By-product feeds were used to completely replace corn grain and soybean feeds. Forty-eight late-lactation cows were assigned to 1 of 4 diets using a randomized complete block design with a 2-wk covariate period followed by a 4-wk experimental period. The covariate diet contained corn grain, soybean meal, and 61% forage. Experimental diets contained chopped wheat straw (WS)/sugar beet pulp at 0/12, 3/9, 6/6, or 9/3 percentages of diet dry matter (DM). Corn silage (20%), alfalfa silage (20%), pelleted corn gluten feed (25.5%), distillers grains (8%), whole cottonseed (5%), cane molasses/whey blend (7%), and vitamin and mineral mix with monensin (2.5%) comprised the rest of diet DM. The WS/sugar beet pulp diets averaged 16.5% crude protein, 35% neutral detergent fiber, and 11% starch (DM basis). Cows consuming the experimental diets maintained a 3.5% fat- and protein-corrected milk production (35.2 kg; standard deviation=5.6 kg) that was numerically similar to that measured in the covariate period (35.3 kg; standard deviation=5.0 kg). Intakes of DM and crude protein declined linearly as WS increased, whereas neutral detergent fiber intake increased linearly. Linear increases in time spent ruminating (from 409 to 502 min/d) and eating (from 156 to 223 min/d) were noted as WS inclusion increased. Yields of milk fat and 3.5% fat-and protein-corrected milk did not change as WS increased, but those of protein and lactose declined linearly. Phosphorous intakes were in excess of recommended levels and decreased linearly with increasing WS inclusion. Nutritional model predictions for multiparous cows were closest to actual performance for the National Research Council 2001 model when a metabolizable protein basis was used; primiparous cow performance was

  8. Effects of forage type, forage to concentrate ratio, and crushed linseed supplementation on milk fatty acid profile in lactating dairy cows

    NARCIS (Netherlands)

    Sterk, A.R.; Johansson, B.E.O.; Taweel, H.Z.H.; Murphy, M.; Vuuren, van A.M.; Hendriks, W.H.; Dijkstra, J.

    2011-01-01

    The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. S

  9. Low forager fertility: demographic characteristic or methodological artifact?

    Science.gov (United States)

    Early, J D

    1985-09-01

    Anthropological literature has long held that traditional foraging populations have low fertility levels. This research examines the number of live births per woman for 9 non-western forager groups who have been investigated in the last 20 years. Data are derived from 1) birth registration systems, 2) surveys conducted during short stays with the group, and 3) surveys conducted as part of longer ethnographic studies. Fertility rates for the groups are 1) 3.5 for the Kiunga area of Papula, New Guinea, 2) 4.2 for Northern Territory Australian aborigines, 3) 5.0 for Cayapo groups in Brazil, 4) 5.3 for Hiowe people of New Guinea, 5) 5.7 for 3 Xavante groups in Brazil, 6) 6.0 for West Alaskan Eskimos, 7) 6.9 for Nunamiut Eskimos of Alaska, 8) 7.6 for the Bisman-Asmat group of Indonesian New Guinea, and 9) 8.4 for the Winikina Warao of Venezuela. Since fertility rates are highest when ethnographic studies, which allow for question clarification, memory recall, and cross-checking, are used, the author believes that high fertility rates most accurately represent forager societies. Research on the Dobe ]Kung (fertility rate - 4.7), may contradict these findings, but the author believes that the ]Kung fertility rates are higher than reported because of infanticide practices, sexual abstinence during lactation, and disease related fertility problems. In summary, the study finds high fertility (7-9 births) in traditional foraging societies. Although the study examines small populations, correlation strength and overall consistency help verify the results.

  10. Fine-scale variability in harbor seal foraging behavior.

    Directory of Open Access Journals (Sweden)

    Kenady Wilson

    Full Text Available Understanding the variability of foraging behavior within a population of predators is important for determining their role in the ecosystem and how they may respond to future ecosystem changes. However, such variability has seldom been studied in harbor seals on a fine spatial scale (<30 km. We used a combination of standard and Bayesian generalized linear mixed models to explore how environmental variables influenced the dive behavior of harbor seals. Time-depth recorders were deployed on harbor seals from two haul-out sites in the Salish Sea in 2007 (n = 18 and 2008 (n = 11. Three behavioral bout types were classified from six dive types within each bout; however, one of these bout types was related to haul-out activity and was excluded from analyses. Deep foraging bouts (Type I were the predominant type used throughout the study; however, variation in the use of bout types was observed relative to haul-out site, season, sex, and light (day/night. The proportional use of Type I and Type II (shallow foraging/traveling bouts differed dramatically between haul-out sites, seasons, sexes, and whether it was day or night; individual variability between seals also contributed to the observed differences. We hypothesize that this variation in dive behavior was related to habitat or prey specialization by seals from different haul-out sites, or individual variability between seals in the study area. The results highlight the potential influence of habitat and specialization on the foraging behavior of harbor seals, and may help explain the variability in diet that is observed between different haul-out site groups in this population.

  11. Methane Production of Different Forages in Ruminal Fermentation

    Directory of Open Access Journals (Sweden)

    S. J. Meale

    2012-01-01

    Full Text Available An in vitro rumen batch culture study was completed to compare effects of common grasses, leguminous shrubs and non-leguminous shrubs used for livestock grazing in Australia and Ghana on CH4 production and fermentation characteristics. Grass species included Andropodon gayanus, Brachiaria ruziziensis and Pennisetum purpureum. Leguminous shrub species included Cajanus cajan, Cratylia argentea, Gliricidia sepium, Leucaena leucocephala and Stylosanthes guianensis and non-leguminous shrub species included Annona senegalensis, Moringa oleifera, Securinega virosa and Vitellaria paradoxa. Leaves were harvested, dried at 55°C and ground through a 1 mm screen. Serum bottles containing 500 mg of forage, modified McDougall’s buffer and rumen fluid were incubated under anaerobic conditions at 39°C for 24 h. Samples of each forage type were removed after 0, 2, 6, 12 and 24 h of incubation for determination of cumulative gas production. Methane production, ammonia concentration and proportions of VFA were measured at 24 h. Concentration of aNDF (g/kg DM ranged from 671 to 713 (grasses, 377 to 590 (leguminous shrubs and 288 to 517 (non-leguminous shrubs. After 24 h of in vitro incubation, cumulative gas, CH4 production, ammonia concentration, proportion of propionate in VFA and IVDMD differed (p<0.05 within each forage type. B. ruziziensis and G. sepium produced the highest cumulative gas, IVDMD, total VFA, proportion of propionate in VFA and the lowest A:P ratios within their forage types. Consequently, these two species produced moderate CH4 emissions without compromising digestion. Grazing of these two species may be a strategy to reduce CH4 emissions however further assessment in in vivo trials and at different stages of maturity is recommended.

  12. Intersexual and temporal variation in foraging ecology of prothonotary warblers during the breeding season

    Science.gov (United States)

    Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J.

    1990-01-01

    We studied foraging ecology of Prothonotary Warblers (Protonotaria citrea) over four breeding seasons to determine if this species exhibited sex-specific or temporal variation in foraging behavior. Significant differences between sexes during the prenestling period were found for foraging height and substrate height (foraging method, plant species/substrate, perch diameter, horizontal location from trunk, and prey location were not significantly different). During the nestling period, this divergence between sexes was evident for foraging height, substrate height, substrate / tree species, and prey location. Additionally, male warblers significantly altered their behavior for all seven foraging variables between the two periods, whereas females exhibited changes similar to those of males for five of the foraging variables. This parallel shift suggests a strong behavioral response by both sexes to proximate factors (such as vegetation structure, and prey abundance and distribution) that varied throughout the breeding season. Sex-specific foraging behavior during the prenestling period was best explained by differences in reproductive responsibilities rather than by the theory of intersexual competition for limited resources. During the nestling period, neither hypothesis by itself explained foraging divergences adequately. However, when integrated with the temporal responses of the warblers to changes in prey availability, reproductive responsibilities seemed to be of primary importance in explaining intersexual niche partitioning during the nestling period. We emphasize the importance of considering both intersexual and intraseasonal variation when quantifying a species' foraging ecology.

  13. How phylogeny and foraging ecology drive the level of chemosensory exploration in lizards and snakes.

    Science.gov (United States)

    Baeckens, S; Van Damme, R; Cooper, W E

    2017-03-01

    The chemical senses are crucial for squamates (lizards and snakes). The extent to which squamates utilize their chemosensory system, however, varies greatly among taxa and species' foraging strategies, and played an influential role in squamate evolution. In lizards, 'Scleroglossa' evolved a state where species use chemical cues to search for food (active foragers), whereas 'Iguania' retained the use of vision to hunt prey (ambush foragers). However, such strict dichotomy is flawed as shifts in foraging modes have occurred in all clades. Here, we attempted to disentangle effects of foraging ecology from phylogenetic trait conservatism as leading cause of the disparity in chemosensory investment among squamates. To do so, we used species' tongue-flick rate (TFR) in the absence of ecological relevant chemical stimuli as a proxy for its fundamental level of chemosensory investigation, that is baseline TFR. Based on literature data of nearly 100 species and using phylogenetic comparative methods, we tested whether and how foraging mode and diet affect baseline TFR. Our results show that baseline TFR is higher in active than ambush foragers. Although baseline TFRs appear phylogenetically stable in some lizard taxa, that is a consequence of concordant stability of foraging mode: when foraging mode shifts within taxa, so does baseline TFR. Also, baseline TFR is a good predictor of prey chemical discriminatory ability, as we established a strong positive relationship between baseline TFR and TFR in response to prey. Baseline TFR is unrelated to diet. Essentially, foraging mode, not phylogenetic relatedness, drives convergent evolution of similar levels of squamate chemosensory investigation.

  14. Effects of predator chemical cues and behavioral biorhythms on foraging activity of terrestrial salamanders.

    Science.gov (United States)

    Maerz, J C; Panebianco, N L; Madison, D M

    2001-07-01

    Red-backed salamanders, Plethodon cinereus, show a variety of alarm responses to chemical cues from eastern garter snakes, Thamnophis sirtalis. We measured the foraging activity of red-backed salamanders exposed to water soiled by a garter snake (fed P. cinereus) or to unsoiled water. Salamanders exposed to snake-soiled water showed less foraging activity than salamanders exposed to unsoiled water; therefore, predators could have nonlethal effects on salamander populations. Our results also show additional factors influenced salamander foraging activity. Salamander foraging activity and responsiveness to chemical cues do not appear to have been affected by sex or food deprivation. Salamander foraging activity does appear to have been influenced by activity biorhythms. Foraging activity of animals in both treatments showed a bimodal periodicity that is consistent with natural activity patterns controlled by internal biorhythms. Exposure to snake-soiled water significantly reduced foraging activity during periods of peak foraging activity, but had a subtler effect on foraging activity during natural lulls in activity. We suggest that both activity biorhythms and exposure to chemical cues are important factors affecting salamander foraging behavior.

  15. The ecological economics of kleptoparasitism: pay-offs from self-foraging versus kleptoparasitism.

    Science.gov (United States)

    Flower, Tom P; Child, Matthew F; Ridley, Amanda R

    2013-01-01

    Animals commonly steal food from other species, termed interspecific kleptoparasitism, but why animals engage in kleptoparasitism compared with alternate foraging tactics, and under what circumstances they do so, is not fully understood. Determining what specific benefits animals gain from kleptoparasitism could provide valuable insight into its evolution. Here, we investigate the benefits of kleptoparasitism for a population of individually recognizable and free-living fork-tailed drongos (Dicrurus adsimilis) in the southern Kalahari Desert. Drongos engaged in two foraging behaviours: self-foraging for small insects or following other species which they kleptoparasitized for larger terrestrial prey that they could not capture themselves. Kleptoparasitism consequently enabled drongos to exploit a new foraging niche. Kleptoparasitism benefitted drongos most in the morning and on colder days because at these times pay-offs from kleptoparasitism remained stable, while those from self-foraging declined. However, drongos engaged in kleptoparasitism less than expected given the overall high (but more variable) pay-offs from this behaviour, suggesting that kleptoparasitism is a risky foraging tactic and may incur additional foraging costs compared with self-foraging. This is the first study to comprehensively investigate the benefits of facultatively engaging in kleptoparasitism, demonstrating that animals may switch to kleptoparasitism to exploit a new foraging niche when pay-offs exceed those from alternate foraging behaviours.

  16. A molecular phylogeny of Dorylus army ants provides evidence for multiple evolutionary transitions in foraging niche

    Directory of Open Access Journals (Sweden)

    Vilhelmsen Lars B

    2007-04-01

    Full Text Available Abstract Background Army ants are the prime arthropod predators in tropical forests, with huge colonies and an evolutionary derived nomadic life style. Five of the six recognized subgenera of Old World Dorylus army ants forage in the soil, whereas some species of the sixth subgenus (Anomma forage in the leaf-litter and some as conspicuous swarm raiders on the forest floor and in the lower vegetation (the infamous driver ants. Here we use a combination of nuclear and mitochondrial DNA sequences to reconstruct the phylogeny of the Dorylus s.l. army ants and to infer the evolutionary transitions in foraging niche and associated morphological adaptations. Results Underground foraging is basal and gave rise to leaf-litter foraging. Leaf-litter foraging in turn gave rise to two derived conditions: true surface foraging (the driver ants and a reversal to subterranean foraging (a clade with most of the extant Dorylus s.s. species. This means that neither the subgenus Anomma nor Dorylus s.s. is monophyletic, and that one of the Dorylus s.s. lineages adopted subterranean foraging secondarily. We show that this latter group evolved a series of morphological adaptations to underground foraging that are remarkably convergent to the basal state. Conclusion The evolutionary transitions in foraging niche were more complex than previously thought, but our comparative analysis of worker morphology lends strong support to the contention that particular foraging niches have selected for very specific worker morphologies. The surprising reversal to underground foraging is therefore a striking example of convergent morphological evolution.

  17. Beneficial Effects of Temperate Forage Legumes that Contain Condensed Tannins

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    Jennifer W. MacAdam

    2015-07-01

    Full Text Available The two temperate forage legumes containing condensed tannins (CT that promote ruminant production are birdsfoot trefoil (Lotus corniculatus L.; BFT and sainfoin (Onobrychis viciifolia Scop.; SF. Both are well-adapted to the cool-temperate climate and alkaline soils of the Mountain West USA. Condensed tannins comprise a diverse family of bioactive chemicals with multiple beneficial functions for ruminants, including suppression of internal parasites and enteric methane. Birdsfoot trefoil contains 10 to 40 g·CT·kg−1 dry matter (DM, while SF contains 30 to 80 g·CT·kg−1 DM. Our studies have focused on these two plant species and have demonstrated consistently elevated rates of gain for beef calves grazing both BFT and SF. Novel results from our BFT research include carcass dressing percentages and consumer sensory evaluations equivalent to feedlot-finished steers and significantly greater than grass-finished steers, but with omega-3 fatty acid concentrations equal to grass-finished beef. We have further demonstrated that ruminants fed BFT or SF will consume more endophyte-infected tall fescue (Schedonorus arundinaceus (Schreb. Dumort. forage or seed than ruminants fed a non-CT forage legume. There is great potential value for sustainable livestock production in the use of highly digestible, nitrogen-fixing legumes containing tannins demonstrated to improve ruminant productivity.

  18. Imidacloprid alters foraging and decreases bee avoidance of predators.

    Directory of Open Access Journals (Sweden)

    Ken Tan

    Full Text Available Concern is growing over the effects of neonicotinoid pesticides, which can impair honey bee cognition. We provide the first demonstration that sublethal concentrations of imidacloprid can harm honey bee decision-making about danger by significantly increasing the probability of a bee visiting a dangerous food source. Apis cerana is a native bee that is an important pollinator of agricultural crops and native plants in Asia. When foraging on nectar containing 40 µg/L (34 ppb imidacloprid, honey bees (Apis cerana showed no aversion to a feeder with a hornet predator, and 1.8 fold more bees chose the dangerous feeder as compared to control bees. Control bees exhibited significant predator avoidance. We also give the first evidence that foraging by A. cerana workers can be inhibited by sublethal concentrations of the pesticide, imidacloprid, which is widely used in Asia. Compared to bees collecting uncontaminated nectar, 23% fewer foragers returned to collect the nectar with 40 µg/L imidacloprid. Bees that did return respectively collected 46% and 63% less nectar containing 20 µg/L and 40 µg/L imidacloprid. These results suggest that the effects of neonicotinoids on honey bee decision-making and other advanced cognitive functions should be explored. Moreover, research should extend beyond the classic model, the European honey bee (A. mellifera, to other important bee species.

  19. Bee Swarm Optimization for Medical Web Information Foraging.

    Science.gov (United States)

    Drias, Yassine; Kechid, Samir; Pasi, Gabriella

    2016-02-01

    The present work is related to Web intelligence and more precisely to medical information foraging. We present here a novel approach based on agents technology for information foraging. An architecture is proposed, in which we distinguish two important phases. The first one is a learning process for localizing the most relevant pages that might interest the user. This is performed on a fixed instance of the Web. The second takes into account the openness and the dynamicity of the Web. It consists on an incremental learning starting from the result of the first phase and reshaping the outcomes taking into account the changes that undergoes the Web. The whole system offers a tool to help the user undertaking information foraging. We implemented the system using a group of cooperative reactive agents and more precisely a colony of artificial bees. In order to validate our proposal, experiments were conducted on MedlinePlus, a benchmark dedicated for research in the domain of Health. The results are promising either for those related to Web regularities and for the response time, which is very short and hence complies the real time constraint.

  20. The FGLamide-allatostatins influence foraging behavior in Drosophila melanogaster.

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    Christine Wang

    Full Text Available Allatostatins (ASTs are multifunctional neuropeptides that generally act in an inhibitory fashion. ASTs were identified as inhibitors of juvenile hormone biosynthesis. Juvenile hormone regulates insect metamorphosis, reproduction, food intake, growth, and development. Drosophila melanogaster RNAi lines of PheGlyLeu-amide-ASTs (FGLa/ASTs and their cognate receptor, Dar-1, were used to characterize roles these neuropeptides and their respective receptor may play in behavior and physiology. Dar-1 and FGLa/AST RNAi lines showed a significant reduction in larval foraging in the presence of food. The larval foraging defect is not observed in the absence of food. These RNAi lines have decreased for transcript levels which encodes cGMP- dependent protein kinase. A reduction in the for transcript is known to be associated with a naturally occurring allelic variation that creates a sitter phenotype in contrast to the rover phenotype which is caused by a for allele associated with increased for activity. The sitting phenotype of FGLa/AST and Dar-1 RNAi lines is similar to the phenotype of a deletion mutant of an AST/galanin-like receptor (NPR-9 in Caenorhabditis elegans. Associated with the foraging defect in C. elegans npr-9 mutants is accumulation of intestinal lipid. Lipid accumulation was not a phenotype associated with the FGLa/AST and Dar-1 RNAi lines.

  1. Resource heterogeneity and foraging behaviour of cattle across spatial scales

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    Demment Montague W

    2009-04-01

    Full Text Available Abstract Background Understanding the mechanisms that influence grazing selectivity in patchy environments is vital to promote sustainable production and conservation of cultivated and natural grasslands. To better understand how patch size and spatial dynamics influence selectivity in cattle, we examined grazing selectivity under 9 different treatments by offering alfalfa and fescue in patches of 3 sizes spaced with 1, 4, and 8 m between patches along an alley. We hypothesized that (1 selectivity is driven by preference for the forage species that maximizes forage intake over feeding scales ranging from single bites to patches along grazing paths, (2 that increasing patch size enhances selectivity for the preferred species, and that (3 increasing distances between patches restricts selectivity because of the aggregation of scale-specific behaviours across foraging scales. Results Cows preferred and selected alfalfa, the species that yielded greater short-term intake rates (P Conclusion We conclude that patch size and spacing affect components of intake rate and, to a lesser extent, the selectivity of livestock at lower hierarchies of the grazing process, particularly by enticing livestock to make more even use of the available species as patches are spaced further apart. Thus, modifications in the spatial pattern of plant patches along with reductions in the temporal and spatial allocation of grazing may offer opportunities to improve uniformity of grazing by livestock and help sustain biodiversity and stability of plant communities.

  2. MACRO NUTRIENTS UPTAKE OF FORAGE GRASSES AT DIFFERENT SALINITY STRESSES

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    F. Kusmiyati

    2014-10-01

    Full Text Available The high concentration of sodium chloride (NaCl in saline soils has negative effects on the growth ofmost plants. The experiment was designed to evaluate macro nutrient uptake (Nitrogen, Phosphorus andPotassium of forage grasses at different NaCl concentrations in growth media. The experiment wasconducted in a greenhouse at Forage Crops Laboratory of Animal Agriculture Faculty, Diponegoro University.Split plot design was used to arrange the experiment. The main plot was forage grasses (Elephant grass(Pennisetum purpureum and King grass (Pennisetum hybrida. The sub plot was NaCl concentrationin growth media (0, 150, and 300 mM. The nitrogen (N, phosphorus (P and potassium (K uptake in shootand root of plant were measured. The result indicated increasing NaCl concentration in growth mediasignificantly decreased the N, P and K uptake in root and shoot of the elephant grass and king grass. Thepercentage reduction percentage of N, P and K uptake at 150 mM and 300 mM were high in elephant grassand king grass. It can be concluded that based on nitrogen, phosphorus and potassium uptake, elephantgrass and king grass are not tolerant to strong and very strong saline soil.

  3. Evidence for acoustic communication among bottom foraging humpback whales.

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    Parks, Susan E; Cusano, Dana A; Stimpert, Alison K; Weinrich, Mason T; Friedlaender, Ari S; Wiley, David N

    2014-12-16

    Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a 'paired burst' sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species.

  4. Co-evolution of learning complexity and social foraging strategies.

    Science.gov (United States)

    Arbilly, Michal; Motro, Uzi; Feldman, Marcus W; Lotem, Arnon

    2010-12-21

    Variation in learning abilities within populations suggests that complex learning may not necessarily be more adaptive than simple learning. Yet, the high cost of complex learning cannot fully explain this variation without some understanding of why complex learning is too costly for some individuals but not for others. Here we propose that different social foraging strategies can favor different learning strategies (that learn the environment with high or low resolution), thereby maintaining variable learning abilities within populations. Using a genetic algorithm in an agent-based evolutionary simulation of a social foraging game (the producer-scrounger game) we demonstrate how an association evolves between a strategy based on independent search for food (playing a producer) and a complex (high resolution) learning rule, while a strategy that combines independent search and following others (playing a scrounger) evolves an association with a simple (low resolution) learning rule. The reason for these associations is that for complex learning to have an advantage, a large number of learning steps, normally not achieved by scroungers, are necessary. These results offer a general explanation for persistent variation in cognitive abilities that is based on co-evolution of learning rules and social foraging strategies.

  5. Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi

    Science.gov (United States)

    Narendra, Ajay; Gourmaud, Sarah; Zeil, Jochen

    2013-01-01

    Ants are efficient navigators, guided by path integration and visual landmarks. Path integration is the primary strategy in landmark-poor habitats, but landmarks are readily used when available. The landmark panorama provides reliable information about heading direction, routes and specific location. Visual memories for guidance are often acquired along routes or near to significant places. Over what area can such locally acquired memories provide information for reaching a place? This question is unusually approachable in the solitary foraging Australian jack jumper ant, since individual foragers typically travel to one or two nest-specific foraging trees. We find that within 10 m from the nest, ants both with and without home vector information available from path integration return directly to the nest from all compass directions, after briefly scanning the panorama. By reconstructing panoramic views within the successful homing range, we show that in the open woodland habitat of these ants, snapshot memories acquired close to the nest provide sufficient navigational information to determine nest-directed heading direction over a surprisingly large area, including areas that animals may have not visited previously. PMID:23804615

  6. Therapeutic Potential of Temperate Forage Legumes: A Review.

    Science.gov (United States)

    Cornara, Laura; Xiao, Jianbo; Burlando, Bruno

    2016-07-29

    The discovery of bioactive molecules from botanical sources is an expanding field, preferentially oriented to plants having a tradition of use in medicine and providing high yields and availability. Temperate forage legumes are Fabaceae species that include worldwide-important crops. These plants possess therapeutic virtues that have not only been used in veterinary and folk medicine, but have also attracted the interest of official medicine. We have examined here Medicago sativa (alfalfa), Trifolium pratense and T. repens (clovers), Melilotus albus and M. officinalis (sweet clovers), Lotus corniculatus (birdsfoot trefoil), Onobrychis viciifolia (sainfoin), Lespedeza capitata (roundhead lespedeza), and Galega officinalis (goat's rue). The phytochemical complexes of these species contain secondary metabolites whose pharmacological potentials deserve investigation. Major classes of compounds include alkaloids and amines, cyanogenic glycosides, flavonoids, coumarins, condensed tannins, and saponins. Some of these phytochemicals have been related to antihypercholesterolemia, antidiabetic, antimenopause, anti-inflammatory, antiedema, anthelmintic, and kidney protective effects. Two widely prescribed drugs have been developed starting from temperate forage legumes, namely, the antithrombotic warfarin, inspired from sweet clover's coumarin, and the antidiabetic metformin, a derivative of sainfoin's guanidine. Available evidence suggests that temperate forage legumes are a potentially important resource for the extraction of active principles to be used as nutraceuticals and pharmaceuticals.

  7. Imidacloprid alters foraging and decreases bee avoidance of predators.

    Science.gov (United States)

    Tan, Ken; Chen, Weiwen; Dong, Shihao; Liu, Xiwen; Wang, Yuchong; Nieh, James C

    2014-01-01

    Concern is growing over the effects of neonicotinoid pesticides, which can impair honey bee cognition. We provide the first demonstration that sublethal concentrations of imidacloprid can harm honey bee decision-making about danger by significantly increasing the probability of a bee visiting a dangerous food source. Apis cerana is a native bee that is an important pollinator of agricultural crops and native plants in Asia. When foraging on nectar containing 40 µg/L (34 ppb) imidacloprid, honey bees (Apis cerana) showed no aversion to a feeder with a hornet predator, and 1.8 fold more bees chose the dangerous feeder as compared to control bees. Control bees exhibited significant predator avoidance. We also give the first evidence that foraging by A. cerana workers can be inhibited by sublethal concentrations of the pesticide, imidacloprid, which is widely used in Asia. Compared to bees collecting uncontaminated nectar, 23% fewer foragers returned to collect the nectar with 40 µg/L imidacloprid. Bees that did return respectively collected 46% and 63% less nectar containing 20 µg/L and 40 µg/L imidacloprid. These results suggest that the effects of neonicotinoids on honey bee decision-making and other advanced cognitive functions should be explored. Moreover, research should extend beyond the classic model, the European honey bee (A. mellifera), to other important bee species.

  8. New Inoculants Containing Lactic Bacteria Applied in Forage Ensiling

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    Teodor Vintila

    2010-05-01

    Full Text Available In a first study, the capacity of lactic bacteria to accumulate biomass in different culture media and temperatures was tested and the biosynthesis parameters were established. In the second study, the strains producing the highest quantity of biomass and determining the most rapid pH drop in culture medium were conditioned in solid supports. The obtained solid products containing lactic bacteria were used to inoculate different types of forages. Ensilage was carried out in laboratory silos made from O2-impermeable plastic flasks, vacuumed using a vacuum pump. The experiment was 2 x 2 factorial with two types of forage (alfalfa and sorghum, each of them inoculated and not inoculated with lactic bacteria. The evolution of lactic bacteria, pH value, and the concentration in volatile acids was verified. In the third experiment, lactic bacteria were used to inoculate silages in farm conditions. The obtained results recommend the tested strain for the improvement of preserving conditions and nutritive value in ensiled forages.

  9. Bust economics: foragers choose high quality habitats in lean times

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    Sonny S. Bleicher

    2016-01-01

    Full Text Available In environments where food resources are spatially variable and temporarily impoverished, consumers that encounter habitat patches with different food density should focus their foraging initially where food density is highest before they move to patches where food density is lower. Increasing missed opportunity costs should drive individuals progressively to patches with lower food density as resources in the initially high food density patches deplete. To test these expectations, we assessed the foraging decisions of two species of dasyurid marsupials (dunnarts: Sminthopsis hirtipes and S. youngsoni during a deep drought, or bust period, in the Simpson Desert of central Australia. Dunnarts were allowed access to three patches containing different food densities using an interview chamber experiment. Both species exhibited clear preference for the high density over the lower food density patches as measured in total harvested resources. Similarly, when measuring the proportion of resources harvested within the patches, we observed a marginal preference for patches with initially high densities. Models analyzing behavioral choices at the population level found no differences in behavior between the two species, but models analyzing choices at the individual level uncovered some variation. We conclude that dunnarts can distinguish between habitat patches with different densities of food and preferentially exploit the most valuable. As our observations were made during bust conditions, experiments should be repeated during boom times to assess the foraging economics of dunnarts when environmental resources are high.

  10. Nitrogen Transfer to Forage Crops from a Caragana Shelterbelt

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    Gazali Issah

    2015-05-01

    Full Text Available Caragana shelterbelts are a common feature of farms in the Northern Great Plains of North America. We investigated if nitrogen (N from this leguminous shrub contributed to the N nutrition of triticale and oat forage crops growing adjacent to the shelterbelt row. Nitrogen transfer was measured using 15N isotope dilution at distances of 2 m, 4 m, 6 m, 15 m and 20 m from the shelterbelt. At 2 m caragana negatively impacted the growth of triticale and oat. At 4 m from the shelterbelt productivity was maximum for both forage crops and corresponded to the highest amount of N originating from caragana. The amount of N transferred from caragana decreased linearly with distance away from the shelterbelt, but even at 20 m from the shelterbelt row measureable amounts of N originating from caragana were detectable in the forage biomass. At 4 m from the shelterbelt approximately 40% of the N in both oat and triticale was from caragana, and at 20 m from the shelterbelt approximately 20% of the N in oat and 8% of the N in triticale was from caragana.

  11. Optimal foraging or predator avoidance: why does the Amazon spider Hingstepeira folisecens (Araneae: Araneidae adopt alternative foraging behaviors?

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    Kátia F. Rito

    Full Text Available ABSTRACT Strategies that increase foraging efficiency may also increase predation risk. We investigated how individuals of Hingstepeira folisecens Hingston, 1932, which build shelters at the orb hub, modulate their foraging behaviors in response to the trade-off between capturing prey and becoming exposed by leaving their shelters. We evaluated whether the position of the prey on the web alters the frequency at which spiders leave their shelters. Hingstepeira folisecens spiders were more likely to capture prey positioned below than above the entrance of the shelter. Moreover, when the prey was near the entrance of the shelter, the spider pulled the threads with the entangled prey without leaving the shelter. Conversely, when the prey was distant from the entrance of the shelter, an "attack" behavior (leaving the shelter was favored. We argue that the "pulling behavior" may be an adaptation to reduce exposure to predators.

  12. California Least Tern Foraging Ecology in Southern California: A Review of Foraging Behavior Relative to Proposed Dredging Locations

    Science.gov (United States)

    2016-05-01

    freshwater species, including killifish (Fundulus parvipinnis) and mosquito fish (Gambusia affinis) (Atwood and ERDC/EL CR-16-3 2 Kelly 1984...event of oil spill. Three portable pools with mosquito fish provided near Pier 400 nesting site. Included surveys at 3 preferred foraging areas...review summarized available information on CLT biology , ecology, and predators in the first four sections; Section 5 is entitled “Known Effects of

  13. Cross-sectional geometry in the humeri of foragers and farmers from the prehispanic American Southwest: exploring patterns in the sexual division of labor.

    Science.gov (United States)

    Ogilvie, Marsha D; Hilton, Charles E

    2011-01-01

    The work effort of prehistoric males relative to females has long been of interest to anthropologists, particularly in foraging versus farming groups. This knowledge requires a clear understanding of the sexual division of labor, or the dichotomy in subsistence roles allocated to males and females. Such research in the Prehispanic American Southwest has been limited. As previous work has shown that bone is the osseous template that reflects in vivo activity levels, it is possible to assess gender-based differences in past work effort using analyses of geometric properties of bone and calculations of bilateral asymmetry. Our research comparatively analyzed upper limb work effort by sex and subsistence in two skeletal samples from disparate economic groups, foragers and farmers, both from similar desert environments. The residentially mobile foragers are from the Lower Pecos region of southwest Texas and the farmers are from the aggregated pueblo of Pottery Mound in south central New Mexico. Humeri from 27 adult foragers (n = 11 males; n = 17 females) and 65 adult farmers (n = 38 males; n = 27 females) were selected for study. All humeri were radiographed and/or scanned and digitized. Statistical comparisons using two-way ANOVAs indicate that female farmers exhibited the greatest humeral strength and the least asymmetry. Relative to all other groups examined, female farmers engaged in higher levels of upper limb work effort implying a substantial economic contribution to their agricultural economy.

  14. Nectar robbing, forager efficiency and seed set: Bumblebees foraging on the self incompatible plant Linaria vulgaris (Scrophulariaceae)

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    Stout, Jane C.; Allen, John A.; Goulson, Dave

    2000-07-01

    In southern England, Linaria vulgaris (common yellow toadflax) suffers from high rates of nectar robbery by bumblebees. In a wild population of L. vulgaris we found that 96 % of open flowers were robbed. Five species of bumblebee were observed foraging on these flowers, although short-tongued species ( Bombus lapidarius, B. lucorum and B. terrestris) robbed nectar whilst longer-tongued ones behaved as legitimate pollinators ( B. hortorum and B. pascuorum). Nectar rewards were highly variable; on average there was less nectar in robbed than in unrobbed flowers, but this difference was not statistically significant. The proportion of flowers containing no nectar was significantly higher for robbed flowers compared with unrobbed flowers. Secondary robbers and legitimate pollinators had similar handling times on flowers and, assuming they select flowers at random to forage on, received approximately the same nectar profit per minute, largely because most flowers had been robbed. There was no significant difference in the number of seeds in pods of robbed flowers and in pods of flowers that were artificially protected against robbing. However, more of the robbed flowers set at least some seed than the unrobbed flowers, possibly as a consequence of the experimental manipulation. We suggest that nectar robbing has little effect on plant fecundity because legitimate foragers are present in the population, and that seed predation and seed abortion after fertilization may be more important factors in limiting seed production in this species.

  15. Contaminants in tracked seabirds showing regional patterns of marine pollution.

    Science.gov (United States)

    Ito, Atsuo; Yamashita, Rei; Takada, Hideshige; Yamamoto, Takashi; Shiomi, Kozue; Zavalaga, Carlos; Abe, Tomoya; Watanabe, Shinichi; Yamamoto, Maki; Sato, Katsufumi; Kohno, Hiroyoshi; Yoda, Ken; Iida, Tomohiko; Watanuki, Yutaka

    2013-07-16

    Ocean-scale monitoring of pollution is challenging. Seabirds are useful indicators because they travel over a broad foraging range. Nevertheless, this coarse spatial resolution is not fine enough to discriminate pollution in a finer scale. Previous studies have demonstrated that pollution levels are higher in the Sea of Japan and South and East China Seas than the Northen Pacific Ocean. To test these findings in a wide-ranging animal, we tracked streaked shearwaters (Calonectris leucomelas) from four islands in Japan using global positioning system (GPS) and measured persistent organic pollutants (POPs) in the oil of their preen glands. The POPs did not change during 6 to 21 days when birds from Awashima were foraging only in the Sea of Japan, while it increased when they crossed to the Pacific through the Tsugaru Strait and foraged along the eastern coast of Hokkaido where industrial cities occur. These results indicate that POPs in the oil reflect relatively short-term exposure. Concentrations of POPs displayed greater variation among regions. Total polychlorinated biphenyls were highest in birds foraging in a small area of the semiclosed Seto Inland Sea surrounded by urbanized coast, p,p'-dichlorodiphenyltrichloroethane (DDT) was highest in birds foraging in the East China Sea, and total hexachlorocyclohexanes were highest in birds foraging in the Sea of Japan. All were lowest in birds foraging in the Pacific. This distribution of POPs concentration partly agrees with previous findings based on mussels, fish, and seawater and possibly reflects the mobility and emission sources of each type of POP. These results highlight the importance of information on the foraging area of highly mobile top predators to make them more effective monitors of regional marine pollution.

  16. Nocturnal activity and foraging of prairie raccoons (Procyon lotor) in North Dakota

    Science.gov (United States)

    Greenwood, R.J.

    1982-01-01

    Nocturnal activity and foraging of 39 radio-equipped raccoons (Procyon lotor) in eastern North Dakota were studied from April-July in 1974-1976. Sixteen of the raccoons were collected after foraging bouts for stomach content analysis. Raccoon activity consisted of running (13%), walking (49%) and local movement in confined areas (38%). Local movement was foraging on large or locally abundant food items. Adult males traveled farther in a night, ran twice as often, and moved locally only half as often as adult females and yearlings. Differences in activity patterns between adult females and yearlings were not detected. There was no difference among age-sex groups in use of foraging habitats. All raccoons foraged extensively in farmyards and wetlands. Stomach content analysis substantiated foraging determinations obtained by radiotelemetry. Principal foods were grain, aquatic animals, rodents, birds and bird eggs.

  17. Avaliação do padrão de fermentação de silagens elaboradas com espécies forrageiras do estrato herbáceo da caatinga nordestina Evaluation of standard fermentation of silages elaborated with forage species of the herbaceous stratum of Brazilian Northeast region

    Directory of Open Access Journals (Sweden)

    Márcia Maria Cândido da Silva

    2004-02-01

    herbaceous stratum of two ecological ranches (SE-1 and SE-2 in the Caatinga area in the state of Paraíba, Brazil. The species presented in the stratum were identified by the classification of plants. To evaluate fermentation pattern, the herbaceous stratum were pricked in forage machine and, after homogenization, a part of it was exposed to sun in order to lose excess of water (wilted. In fresh and wilted samples, buffering capacity (BC and soluble carbohydrate content in the DM were determined. In small PVC silos, 48 silages were made for each ecological ranch, which were opened after 3,7,14,21,28 and 35 stocked days to evaluate dry matters (DM variations, pH and N-NH3. Variance and regression analyses were made for the studied characteristics. Significant wilted effect was observed in SE-1 silages. Regression analyses stimulated quadratic equations for DM and pH just for fresh silages. For SE-2 silages, the wilted exercised influence on the DM, but the regression analyses did not estimate equations for this characteristic. Related to pH, these equations were estimated: linear for fresh silages and quadratic for the wilted. Linear equations were obtained to the N-NH3 for both silages that were studied in the ranches. SE-1 silages did not present satisfactory fermentation, that probably happened because of the silage high humidity contents, as well as legumes participation. The wilted SE-2 silages presented satisfactory fermentation pattern.

  18. Food limitation of sea lion pups and the decline of forage off central and southern California.

    Science.gov (United States)

    McClatchie, Sam; Field, John; Thompson, Andrew R; Gerrodette, Tim; Lowry, Mark; Fiedler, Paul C; Watson, William; Nieto, Karen M; Vetter, Russell D

    2016-03-01

    California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5-38° N) for a decade, suggesting that trends in forage are environmentally driven.

  19. Multiple-stage decisions in a marine central-place forager

    Science.gov (United States)

    Friedlaender, Ari S.; Johnston, David W.; Tyson, Reny B.; Kaltenberg, Amanda; Goldbogen, Jeremy A.; Stimpert, Alison K.; Curtice, Corrie; Hazen, Elliott L.; Halpin, Patrick N.; Read, Andrew J.; Nowacek, Douglas P.

    2016-01-01

    Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator–prey interactions and underscores the need to simultaneously measure prey distribution in marine central place

  20. Multiple-stage decisions in a marine central-place forager

    Science.gov (United States)

    Friedlaender, Ari S.; Johnston, David W.; Tyson, Reny B.; Kaltenberg, Amanda; Goldbogen, Jeremy A.; Stimpert, Alison K.; Curtice, Corrie; Hazen, Elliott L.; Halpin, Patrick N.; Read, Andrew J.; Nowacek, Douglas P.

    2016-05-01

    Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator-prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager

  1. Harvester Ant Colony Variation in Foraging Activity and Response to Humidity

    OpenAIRE

    Gordon, Deborah M.; Dektar, Katherine N.; Noa Pinter-Wollman

    2013-01-01

    Collective behavior is produced by interactions among individuals. Differences among groups in individual response to interactions can lead to ecologically important variation among groups in collective behavior. Here we examine variation among colonies in the foraging behavior of the harvester ant, Pogonomyrmex barbatus. Previous work shows how colonies regulate foraging in response to food availability and desiccation costs: the rate at which outgoing foragers leave the nest depends on the ...

  2. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies

    OpenAIRE

    Ellis, Samuel; Robinson, Elva J. H.

    2015-01-01

    A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non...

  3. A Hybrid Bacterial Foraging Algorithm For Solving Job Shop Scheduling Problems

    OpenAIRE

    Narendhar, S.; T Amudha

    2012-01-01

    Bio-Inspired computing is the subset of Nature-Inspired computing. Job Shop Scheduling Problem is categorized under popular scheduling problems. In this research work, Bacterial Foraging Optimization was hybridized with Ant Colony Optimization and a new technique Hybrid Bacterial Foraging Optimization for solving Job Shop Scheduling Problem was proposed. The optimal solutions obtained by proposed Hybrid Bacterial Foraging Optimization algorithms are much better when compared with the solution...

  4. Opportunities to enhance performance and efficiency through nutrient synchrony in forage-fed ruminants.

    Science.gov (United States)

    Hersom, M J

    2008-04-01

    Increasingly, the need for optimized nutrient utilization to address increasing production costs and environmental considerations will necessitate opportunities to improve nutrient synchrony. Historically, attempts at synchronizing nutrient supply in ruminants, particularly in cattle consuming high-forage diets, have met with variable results. The success of nutrient synchrony has been measured primarily in ruminants by increases in microbial yield, microbial efficiency, nutrient utilization, and to a lesser extent, animal performance. Successful synchrony of nutrient supply to cattle consuming forage-based diets faces several challenges. From a feed supply aspect, the challenges to nutrient synchrony include accurately measuring forage intake and consumed forage chemical composition. The issue of forage intake and chemical composition is perhaps the most daunting for producers grazing cattle. Indeed, for forage-fed cattle, the availability of forage protein and carbohydrate can be the most asynchronous aspect of the diet. In most grazed forages, digestion rates of the carbohydrate fractions are much slower than that of the corresponding protein fractions. Additionally, the forage-supplement interaction exerts a large impact on the synchrony of nutrients. The supplemental feedstuffs compose the component of the nutrient synchrony scenario that is most often manipulated to influence synchrony. The supplement type (e.g., starch vs. fiber, dry vs. liquid), nutrient profile, and degradation rates are often prime considerations associated with nutrient synchrony on high forage diets. Other considerations that warrant attention include temporal intake patterns of the forage and supplement, increased use and types of coproduct supplements, and an assessment of the success of nutrient synchrony. Synchronization of nutrient utilization by forage-fed ruminants has and will continue to encounter challenges for successful outcomes. Ultimately it is the improvement in animal

  5. Does foraging mode affect metabolic responses to feeding? A study of pygopodid lizards

    Directory of Open Access Journals (Sweden)

    Michael WALL, Michael B. THOMPSON, Richard SHINE

    2013-10-01

    Full Text Available Foraging mode (ambush vs. active profoundly affects many aspects of organismal biology, including metabolic rates and their relationship with food intake. Previous studies on snakes suggest that ambushers tend to have lower standard metabolic rates (SMR and higher energetic costs of digestion and assimilation of prey (specific dynamic action, or SDA than do active foragers. However, phylogenetic considerations may be at least partly responsible for such patterns, as foraging mode is strongly conserved evolutionarily and most SDA studies have focused on species from only two lineages of ambush foragers (pythonid and viperid snakes and one lineage of active foragers (colubrid snakes. We sought to deconfound the effects of phylogeny and foraging mode, investigating SMR and SDA in two closely related pygopodid lizards, the common scaly-foot Pygopus lepidopodus (active forager and Burton’s legless lizard Lialis burtonis (ambush forager. Consistent with the pattern seen in snakes, L. burtonis exhibits a significantly lower SMR and a higher SDA than does P. lepidopodus. The magnitude of SDA in L. burtonis is comparable to that of some pythons and vipers, providing yet more evidence for the remarkable convergence between this species and ambush-foraging snakes [Current Zoology 59 (5: 618–625, 2013]. 

  6. Diet Overlap and Foraging Activity between Feral Pigs and Native Peccaries in the Pantanal.

    Science.gov (United States)

    Galetti, Mauro; Camargo, Hiléia; Siqueira, Tadeu; Keuroghlian, Alexine; Donatti, Camila I; Jorge, Maria Luisa S P; Pedrosa, Felipe; Kanda, Claudia Z; Ribeiro, Milton C

    2015-01-01

    Inter-specific competition is considered one of the main selective pressures affecting species distribution and coexistence. Different species vary in the way they forage in order to minimize encounters with their competitors and with their predators. However, it is still poorly known whether and how native species change their foraging behavior in the presence of exotic species, particularly in South America. Here we compare diet overlap of fruits and foraging activity period of two sympatric native ungulates (the white-lipped peccary, Tayassu pecari, and the collared peccary, Pecari tajacu) with the invasive feral pig (Sus scrofa) in the Brazilian Pantanal. We found high diet overlap between white-lipped peccaries and feral pigs, but low overlap between collared peccaries and feral pigs. Furthermore, we found that feral pigs may influence the foraging period of both native peccaries, but in different ways. In the absence of feral pigs, collared peccary activity peaks in the early evening, possibly allowing them to avoid white-lipped peccary activity peaks, which occur in the morning. In the presence of feral pigs, collared peccaries forage mostly in early morning, while white-lipped peccaries forage throughout the day. Our results indicate that collared peccaries may avoid foraging at the same time as white-lipped peccaries. However, they forage during the same periods as feral pigs, with whom they have lower diet overlap. Our study highlights how an exotic species may alter interactions between native species by interfering in their foraging periods.

  7. The dynamics of foraging trails in the tropical arboreal ant Cephalotes goniodontus.

    Directory of Open Access Journals (Sweden)

    Deborah M Gordon

    Full Text Available The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4-8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony's trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest.

  8. The dynamics of foraging trails in the tropical arboreal ant Cephalotes goniodontus.

    Science.gov (United States)

    Gordon, Deborah M

    2012-01-01

    The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4-8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony's trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest.

  9. Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard

    National Research Council Canada - National Science Library

    Drakeley, Maximilian; Lapiedra, Oriol; Kolbe, Jason J

    2015-01-01

    .... We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines...

  10. Foraging enrichment modulates open field response to monosodium glutamate in mice

    National Research Council Canada - National Science Library

    Onaolapo, Olakunle J; Onaolapo, Adejoke Y; Akanmu, Moses A; Olayiwola, Gbola

    2015-01-01

    Environmental enrichment can enhance expression of species-specific behaviour. While foraging enrichment is encouraged in laboratory animals, its impact on novelty induced behaviour remain largely unknown...

  11. Simulating secondary succession of elk forage values in a managed forest landscape, western Washington

    Science.gov (United States)

    Jenkins, Kurt J.; Starkey, Edward E.

    1996-01-01

    Modern timber management practices often influence forage production for elk (Cervus elaphus) on broad temporal and spatial scales in forested landscapes. We incorporated site-specific information on postharvesting forest succession and forage characteristics in a simulation model to evaluate past and future influences of forest management practices on forage values for elk in a commercially managed Douglas fir (Pseudotsuga menziesii, PSME)-western hemlock (Tsuga heterophylla, TSHE) forest in western Washington. We evaluated future effects of: (1) clear-cut logging 0, 20, and 40% of harvestable stands every five years; (2) thinning 20-year-old Douglas fir forests; and (3) reducing the harvesting cycle from 60 to 45 years. Reconstruction of historical patterns of vegetation succession indicated that forage values peaked in the 1960s and declined from the 1970s to the present, but recent values still were higher than may have existed in the unmanaged landscape in 1945. Increased forest harvesting rates had little short-term influence on forage trends because harvestable stands were scarce. Simulations of forest thinning also produced negligible benefits because thinning did not improve forage productivity appreciably at the stand level. Simulations of reduced harvesting cycles shortened the duration of declining forage values from approximately 30 to 15 years. We concluded that simulation models are useful tools for examining landscape responses of forage production to forest management strategies, but the options examined provided little potential for improving elk forages in the immediate future.

  12. Diet Overlap and Foraging Activity between Feral Pigs and Native Peccaries in the Pantanal.

    Directory of Open Access Journals (Sweden)

    Mauro Galetti

    Full Text Available Inter-specific competition is considered one of the main selective pressures affecting species distribution and coexistence. Different species vary in the way they forage in order to minimize encounters with their competitors and with their predators. However, it is still poorly known whether and how native species change their foraging behavior in the presence of exotic species, particularly in South America. Here we compare diet overlap of fruits and foraging activity period of two sympatric native ungulates (the white-lipped peccary, Tayassu pecari, and the collared peccary, Pecari tajacu with the invasive feral pig (Sus scrofa in the Brazilian Pantanal. We found high diet overlap between white-lipped peccaries and feral pigs, but low overlap between collared peccaries and feral pigs. Furthermore, we found that feral pigs may influence the foraging period of both native peccaries, but in different ways. In the absence of feral pigs, collared peccary activity peaks in the early evening, possibly allowing them to avoid white-lipped peccary activity peaks, which occur in the morning. In the presence of feral pigs, collared peccaries forage mostly in early morning, while white-lipped peccaries forage throughout the day. Our results indicate that collared peccaries may avoid foraging at the same time as white-lipped peccaries. However, they forage during the same periods as feral pigs, with whom they have lower diet overlap. Our study highlights how an exotic species may alter interactions between native species by interfering in their foraging periods.

  13. Forest or the trees: At what scale do elephants make foraging decisions?

    Science.gov (United States)

    Shrader, Adrian M.; Bell, Caroline; Bertolli, Liandra; Ward, David

    2012-07-01

    For herbivores, food is distributed spatially in a hierarchical manner ranging from plant parts to regions. Ultimately, utilisation of food is dependent on the scale at which herbivores make foraging decisions. A key factor that influences these decisions is body size, because selection inversely relates to body size. As a result, large animals can be less selective than small herbivores. Savanna elephants (Loxodonta africana) are the largest terrestrial herbivore. Thus, they represent a potential extreme with respect to unselective feeding. However, several studies have indicated that elephants prefer specific habitats and certain woody plant species. Thus, it is unclear at which scale elephants focus their foraging decisions. To determine this, we recorded the seasonal selection of habitats and woody plant species by elephants in the Ithala Game Reserve, South Africa. We expected that during the wet season, when both food quality and availability were high, that elephants would select primarily for habitats. This, however, does not mean that they would utilise plant species within these habitats in proportion to availability, but rather would show a stronger selection for habitats compared to plants. In contrast, during the dry season when food quality and availability declined, we expected that elephants would shift and select for the remaining high quality woody species across all habitats. Consistent with our predictions, elephants selected for the larger spatial scale (i.e. habitats) during the wet season. However, elephants did not increase their selection of woody species during the dry season, but rather increased their selection of habitats relative to woody plant selection. Unlike a number of earlier studies, we found that that neither palatability (i.e. crude protein, digestibility, and energy) alone nor tannin concentrations had a significant effect for determining the elephants' selection of woody species. However, the palatability:tannin ratio was

  14. REFORMA: a new project for identification and selection of resilient, water- and energy-efficient forage and feed crops for Mediterranean agricultural systems

    OpenAIRE

    Annicchiarico, P.; C. Porqueddu; Julier, Bernadette; Pecetti, L; Abbas, K.; Abdelguerfi, A.; Bouizgaren, A.; Brummer, E. C.; Burstin, Judith; T. Hayek; Thami-Alami, I.

    2012-01-01

    Crop-livestock and feed systems have huge importance for Mediterranean regions to satisfy the increasing demand for animal products, increase the economic stability of smallholders and produce typical animal products with high added-value, while contributing to sustainable farming, environment protection and efficient nutrient cycling. These systems are threatened, however, by the marked insufficiency of high-protein feedstuff, the overexploitation of forage resources, the increasing costs an...

  15. Estimating yields of salt- and water-stressed forages with remote sensing in the visible and near infrared.

    Science.gov (United States)

    Poss, J A; Russell, W B; Grieve, C M

    2006-01-01

    In arid irrigated regions, the proportion of crop production under deficit irrigation with poorer quality water is increasing as demand for fresh water soars and efforts to prevent saline water table development occur. Remote sensing technology to quantify salinity and water stress effects on forage yield can be an important tool to address yield loss potential when deficit irrigating with poor water quality. Two important forages, alfalfa (Medicago sativa L.) and tall wheatgrass (Agropyron elongatum L.), were grown in a volumetric lysimeter facility where rootzone salinity and water content were varied and monitored. Ground-based hyperspectral canopy reflectance in the visible and near infrared (NIR) were related to forage yields from a broad range of salinity and water stress conditions. Canopy reflectance spectra were obtained in the 350- to 1000-nm region from two viewing angles (nadir view, 45 degrees from nadir). Nadir view vegetation indices (VI) were not as strongly correlated with leaf area index changes attributed to water and salinity stress treatments for both alfalfa and wheatgrass. From a list of 71 VIs, two were selected for a multiple linear-regression model that estimated yield under varying salinity and water stress conditions. With data obtained during the second harvest of a three-harvest 100-d growing period, regression coefficients for each crop were developed and then used with the model to estimate fresh weights for preceding and succeeding harvests during the same 100-d interval. The model accounted for 72% of the variation in yields in wheatgrass and 94% in yields of alfalfa within the same salinity and water stress treatment period. The model successfully predicted yield in three out of four cases when applied to the first and third harvest yields. Correlations between indices and yield increased as canopy development progressed. Growth reductions attributed to simultaneous salinity and water stress were well characterized, but the

  16. Regionalism, Regionalization and Regional Development

    Directory of Open Access Journals (Sweden)

    Liviu C. Andrei

    2016-03-01

    Full Text Available Sustained development is a concept associating other concepts, in its turn, in the EU practice, e.g. regionalism, regionalizing and afferent policies, here including structural policies. This below text, dedicated to integration concepts, will limit on the other hand to regionalizing, otherwise an aspect typical to Europe and to the EU. On the other hand, two aspects come up to strengthen this field of ideas, i.e. the region (al-regionalism-(regional development triplet has either its own history or precise individual outline of terms.

  17. Life history, cognition and the evolution of complex foraging niches.

    Science.gov (United States)

    Schuppli, Caroline; Graber, Sereina M; Isler, Karin; van Schaik, Carel P

    2016-03-01

    Animal species that live in complex foraging niches have, in general, improved access to energy-rich and seasonally stable food sources. Because human food procurement is uniquely complex, we ask here which conditions may have allowed species to evolve into such complex foraging niches, and also how niche complexity is related to relative brain size. To do so, we divided niche complexity into a knowledge-learning and a motor-learning dimension. Using a sample of 78 primate and 65 carnivoran species, we found that two life-history features are consistently correlated with complex niches: slow, conservative development or provisioning of offspring over extended periods of time. Both act to buffer low energy yields during periods of learning, and may thus act as limiting factors for the evolution of complex niches. Our results further showed that the knowledge and motor dimensions of niche complexity were correlated with pace of development in primates only, and with the length of provisioning in only carnivorans. Accordingly, in primates, but not carnivorans, living in a complex foraging niche requires enhanced cognitive abilities, i.e., a large brain. The patterns in these two groups of mammals show that selection favors evolution into complex niches (in either the knowledge or motor dimension) in species that either develop more slowly or provision their young for an extended period of time. These findings help to explain how humans constructed by far the most complex niche: our ancestors managed to combine slow development (as in other primates) with systematic provisioning of immatures and even adults (as in carnivorans). This study also provides strong support for the importance of ecological factors in brain size evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Ants can learn to forage on one-way trails.

    Directory of Open Access Journals (Sweden)

    Pedro Leite Ribeiro

    Full Text Available The trails formed by many ant species between nest and food source are two-way roads on which outgoing and returning workers meet and touch each other all along. The way to get back home, after grasping a food load, is to take the same route on which they have arrived from the nest. In many species such trails are chemically marked by pheromones providing orientation cues for the ants to find their way. Other species rely on their vision and use landmarks as cues. We have developed a method to stop foraging ants from shuttling on two-way trails. The only way to forage is to take two separate roads, as they cannot go back on their steps after arriving at the food or at the nest. The condition qualifies as a problem because all their orientation cues -- chemical, visual or any other -- are disrupted, as all of them cannot but lead the ants back to the route on which they arrived. We have found that workers of the leaf-cutting ant Atta sexdens rubropilosa can solve the problem. They could not only find the alternative way, but also used the unidirectional traffic system to forage effectively. We suggest that their ability is an evolutionary consequence of the need to deal with environmental irregularities that cannot be negotiated by means of excessively stereotyped behavior, and that it is but an example of a widespread phenomenon. We also suggest that our method can be adapted to other species, invertebrate and vertebrate, in the study of orientation, memory, perception, learning and communication.

  19. Can video playback provide social information for foraging blue tits?

    Science.gov (United States)

    Hämäläinen, Liisa; Rowland, Hannah M; Mappes, Johanna; Thorogood, Rose

    2017-01-01

    Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits (Cyanistes caeruleus) videos of demonstrators discovering palatable or aversive prey (injected with bitter-tasting Bitrex) from coloured feeding cups. First we quantify variation in demonstrators' responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show that focal blue tits respond differently to the presence of a demonstrator on a video screen, depending on whether demonstrators discover palatable or aversive prey. Focal birds faced the video screen more during aversive prey presentations, and made more head turns. Regardless of prey type, focal birds also hopped more frequently during the presence of a demonstrator (compared to a control video of a different coloured feeding cup in an empty cage). Finally, we tested if demonstrators' behaviour affected focal birds' food preferences by giving individuals a choice to forage from the same cup as a demonstrator, or from the cup in the control video. We found that only half of the individuals made their choice in accordance to social information in the videos, i.e., their foraging choices were not different from random. Individuals that chose in accordance with a demonstrator, however, made their choice faster than individuals that chose an alternative cup. Together, our results suggest that video playback can provide social cues to blue tits, but individuals vary greatly in how they use this information in their foraging decisions.

  20. Can video playback provide social information for foraging blue tits?

    Directory of Open Access Journals (Sweden)

    Liisa Hämäläinen

    2017-03-01

    Full Text Available Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits (Cyanistes caeruleus videos of demonstrators discovering palatable or aversive prey (injected with bitter-tasting Bitrex from coloured feeding cups. First we quantify variation in demonstrators’ responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show that focal blue tits respond differently to the presence of a demonstrator on a video screen, depending on whether demonstrators discover palatable or aversive prey. Focal birds faced the video screen more during aversive prey presentations, and made more head turns. Regardless of prey type, focal birds also hopped more frequently during the presence of a demonstrator (compared to a control video of a different coloured feeding cup in an empty cage. Finally, we tested if demonstrators’ behaviour affected focal birds’ food preferences by giving individuals a choice to forage from the same cup as a demonstrator, or from the cup in the control video. We found that only half of the individuals made their choice in accordance to social information in the videos, i.e., their foraging choices were not different from random. Individuals that chose in accordance with a demonstrator, however, made their choice faster than individuals that chose an alternative cup. Together, our results suggest that video playback can provide social cues to blue tits, but individuals vary greatly in how they use this information in their foraging decisions.

  1. Transport infrastructure shapes foraging habitat in a raptor community.

    Science.gov (United States)

    Planillo, Aimara; Kramer-Schadt, Stephanie; Malo, Juan E

    2015-01-01

    Transport infrastructure elements are widespread and increasing in size and length in many countries, with the subsequent alteration of landscapes and wildlife communities. Nonetheless, their effects on habitat selection by raptors are still poorly understood. In this paper, we analyzed raptors' foraging habitat selection in response to conventional roads and high capacity motorways at the landscape scale, and compared their effects with those of other variables, such as habitat structure, food availability, and presence of potential interspecific competitors. We also analyzed whether the raptors' response towards infrastructure depends on the spatial scale of observation, comparing the attraction or avoidance behavior of the species at the landscape scale with the response of individuals observed in the proximity of the infrastructure. Based on ecological hypotheses for foraging habitat selection, we built generalized linear mixed models, selected the best models according to Akaike Information Criterion and assessed variable importance by Akaike weights. At the community level, the traffic volume was the most relevant variable in the landscape for foraging habitat selection. Abundance, richness, and diversity values reached their maximum at medium traffic volumes and decreased at highest traffic volumes. Individual species showed different degrees of tolerance toward traffic, from higher abundance in areas with high traffic values to avoidance of it. Medium-sized opportunistic raptors increased their abundance near the traffic infrastructures, large scavenger raptors avoided areas with higher traffic values, and other species showed no direct response to traffic but to the presence of prey. Finally, our cross-scale analysis revealed that the effect of transport infrastructures on the behavior of some species might be detectable only at a broad scale. Also, food availability may attract raptor species to risky areas such as motorways.

  2. Condensed tannins and flavonoids from the forage legume sulla (Hedysarum coronarium).

    Science.gov (United States)

    Tibe, Olekile; Meagher, Lucy P; Fraser, Karl; Harding, David R K

    2011-09-14

    The condensed tannin concentrations and composition and the characterization of the phenolic constituents in the leaves of the forage legume sulla (Hedysarum coronarium), a biennial forage legume found in temperate agricultural regions, were studied. The colorimetric butanol-HCl assay was used for the quantitation of the seasonal condensed tannin concentrations in the leaves of sulla. Fractionation of extracts on Sephadex LH-20 using step elution with aqueous methanol, followed with aqueous acetone or gradient elution with water, aqueous methanol, and aqueous acetone, gave condensed tannin and flavonoid fractions. The chemical characteristics of the purified condensed tannin fractions were studied by acid-catalyzed degradation with benzyl mercaptan and electrospray ionization mass spectrometry (ESI-MS). Thiolysis revealed that epigallocatechin was the major extender unit (15-75%) while gallocatechin was the major terminal unit (50-66%), thus indicating the extractable sulla condensed tannin fraction as the prodelphinidin type. Condensed tannin oligomers to polymers obtained from Sephadex LH-20 gradient fractions ranged between 2.9 and 46 mDP. The homo- and heterogeneous oligomer ions in condensed tannin gradient fractions detected by ESI-MS ranged from 2 to 10 DP and are consistent with the values obtained by thiolysis (2.9-6.9 DP). Lower molecular weight phenolics, including flavonoids and phenolic acids, were characterized by liquid chromatography atmospheric pressure chemical ionization mass spectrometry (LC-APCI/MS) and ESI/MS/MS on a linear ion trap. The flavonoids extracted with aqueous acetone and methanol from sulla leaves and identified included kaempferol, rutin, quercetin-7-O-α-L-rhamnosyl-3-O-glucosylrhamnoside, quercetin-3-O-α-L-rhamnosyl-7-O-glucoside, kaempferol-3-O-β-D-glucoside-dirhamnoside, genistein-7-O-β-D-glucosyl-6″-O-malonate, formononetin-7-O-β-D-glucoside-6″-O-malonate, and afrormosin and the phenolic acid chlorogenic acid.

  3. Activity time budget during foraging trips of emperor penguins.

    Directory of Open Access Journals (Sweden)

    Shinichi Watanabe

    Full Text Available We developed an automated method using depth and one axis of body acceleration data recorded by animal-borne data loggers to identify activities of penguins over long-term deployments. Using this technique, we evaluated the activity time budget of emperor penguins (n = 10 both in water and on sea ice during foraging trips in chick-rearing season. During the foraging trips, emperor penguins alternated dive bouts (4.8 ± 4.5 h and rest periods on sea ice (2.5 ± 2.3 h. After recorder deployment and release near the colony, the birds spent 17.9 ± 8.4% of their time traveling until they reached the ice edge. Once at the ice edge, they stayed there more than 4 hours before the first dive. After the first dive, the mean proportions of time spent on the ice and in water were 30.8 ± 7.4% and 69.2 ± 7.4%, respectively. When in the water, they spent 67.9 ± 3.1% of time making dives deeper than 5 m. Dive activity had no typical diurnal pattern for individual birds. While in the water between dives, the birds had short resting periods (1.2 ± 1.7 min and periods of swimming at depths shallower than 5 m (0.25 ± 0.38 min. When the birds were on the ice, they primarily used time for resting (90.3 ± 4.1% of time and spent only 9.7 ± 4.1% of time traveling. Thus, it appears that, during foraging trips at sea, emperor penguins traveled during dives >5 m depth, and that sea ice was primarily used for resting. Sea ice probably provides refuge from natural predators such as leopard seals. We also suggest that 24 hours of sunlight and the cycling of dive bouts with short rest periods on sea ice allow emperor penguins to dive continuously throughout the day during foraging trips to sea.

  4. Mucin glycan foraging in the human gut microbiome

    OpenAIRE

    Tailford, Louise E; Crost, Emmanuelle H.; Kavanaugh, Devon; Juge, Nathalie

    2015-01-01

    The availability of host and dietary carbohydrates in the gastrointestinal (GI) tract plays a key role in shaping the structure-function of the microbiota. In particular, some gut bacteria have the ability to forage on glycans provided by the mucus layer covering the GI tract. The O-glycan structures present in mucin are diverse and complex, consisting predominantly of core 1-4 mucin-type O-glycans containing α- and β- linked N-acetyl-galactosamine, galactose and N-acetyl-glucosamine. These c...

  5. Leucaena forage production trials based at Ciawi, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Petheram, R.J.; Pandjaitan, M.; Liano, J.

    1982-01-01

    Results from two village studies showed that dry matter yield of Leucaena leucocephala cultivar Cunningham was greater at a cutting height of 50 cm than at 10 cm and on weeded than on unweeded plots. Leucaena could be established in villages using seedlings raised in a seedbed, pulled at age 5 months and stored under wet sacks for 3-15 days before transplanting. This is cheaper than using seedlings in plastic pots. A brief description is given of an agroforestry system in West Timor that uses Leucaena as forage.

  6. Characterizing Variation of Isotopic Markers in Northern Alaskan Caribou Forages

    Science.gov (United States)

    VanSomeren, L.; Barboza, P. S.; Gustine, D. D.; Parrett, L. S.; Stricker, C. A.

    2013-12-01

    Isotopic markers in feces and tissues are a potential tool for monitoring the importance of feeding areas for migratory herbivores such as caribou (Rangifer tarandus). Many of these techniques are currently limited by gaps in our knowledge of how these isotopic signatures vary over the landscape. We collected seven species of preferred caribou forages along a latitudinal gradient in the summer ranges of the Central Arctic (9 sites) and Teshekpuk Lake (4 sites) caribou herds during 2011 and 2012. We analyzed forages at peak protein content and at the end of the season to characterize temporal, species-specific, and spatial variation in isotopic markers. The availability of C and N was measured by digestion in vitro. Isotopic signatures of digested samples were used to calculate fractionation that would bias the isotopic signature of feces. The range of values for isotopes (all values ‰) of nitrogen (δ15N -9.5 - +4.3), and sulfur (δ34S -3.6 - +15.5) were greater than those for carbon (δ13C -30.5 - -24.9). Small declines in forage δ13C with latitude (Carex aquatilis, Eriophorum vaginatum, Salix pulchra, and S. richardsonii [all P Sedges (Carex and Eriophorum) were significantly higher in δ15N than Salix spp. and other dicots (2.0 × 1.1 vs. -2.9 × 2.2; P < 0.01). For Salix spp., δ15N was consistent over the season and between years. Fractionation of δ15N in early season forages was 0.2 × 1.8 and not related to N availability (60% × 17%). For S. pulchra, δ34S may indicate usage of coastal habitats over foothills because δ34S was higher on the coastal plain than in the foothills (11.1 × 3.3 and 3.1 × 2.6; P < 0.01). Isotopic ratios in N and S show the greatest promise for tracking diet and location of migratory caribou whereas the narrow range in δ13C is affected by species, season and location.

  7. Collective Energy Foraging of Robot Swarms and Robot Organisms

    CERN Document Server

    Kernbach, Serge

    2011-01-01

    Cooperation and competition among stand-alone swarm agents increase collective fitness of the whole system. A principally new kind of collective systems is demonstrated by some bacteria and fungi, when they build symbiotic organisms. Symbiotic life forms emerge new functional and self-developmental capabilities, which allow better survival of swarm agents in different environments. In this paper we consider energy foraging scenario for two robotic species, swarm robots and symbiotic robot organism. It is indicated that aggregation of microrobots into a robot organism can provide better functional fitness for the whole group. A prototype of microrobots capable of autonomous aggregation and disaggregation are shown.

  8. Activity time budget during foraging trips of emperor penguins.

    Science.gov (United States)

    Watanabe, Shinichi; Sato, Katsufumi; Ponganis, Paul J

    2012-01-01

    We developed an automated method using depth and one axis of body acceleration data recorded by animal-borne data loggers to identify activities of penguins over long-term deployments. Using this technique, we evaluated the activity time budget of emperor penguins (n = 10) both in water and on sea ice during foraging trips in chick-rearing season. During the foraging trips, emperor penguins alternated dive bouts (4.8 ± 4.5 h) and rest periods on sea ice (2.5 ± 2.3 h). After recorder deployment and release near the colony, the birds spent 17.9 ± 8.4% of their time traveling until they reached the ice edge. Once at the ice edge, they stayed there more than 4 hours before the first dive. After the first dive, the mean proportions of time spent on the ice and in water were 30.8 ± 7.4% and 69.2 ± 7.4%, respectively. When in the water, they spent 67.9 ± 3.1% of time making dives deeper than 5 m. Dive activity had no typical diurnal pattern for individual birds. While in the water between dives, the birds had short resting periods (1.2 ± 1.7 min) and periods of swimming at depths shallower than 5 m (0.25 ± 0.38 min). When the birds were on the ice, they primarily used time for resting (90.3 ± 4.1% of time) and spent only 9.7 ± 4.1% of time traveling. Thus, it appears that, during foraging trips at sea, emperor penguins traveled during dives >5 m depth, and that sea ice was primarily used for resting. Sea ice probably provides refuge from natural predators such as leopard seals. We also suggest that 24 hours of sunlight and the cycling of dive bouts with short rest periods on sea ice allow emperor penguins to dive continuously throughout the day during foraging trips to sea.

  9. Sex-specific kleptoparasitic foraging in ant-eating spiders

    DEFF Research Database (Denmark)

    Martisová, Martina; Bilde, T.; Pekar, Stano

    2009-01-01

    . To investigate this hypothesis, we studied the effect of sex and life history stage on the frequency of kleptoparasitism in ant-eating spiders of the genus Zodarion in the field. These spiders use a special capture technique involving a quick attack on an ant that is left unguarded by spiders for several minutes......, providing ample opportunities for kleptoparasitism. We found that adult females consistently hunted actively, while adult males ceased active prey capture and instead engaged in kleptoparasitism. Juvenile spiders were active hunters irrespective of sex. Consistent with an ontogenetic shift in foraging...

  10. When Michaelis and Menten met Holling: towards a mechanistic theory of plant nutrient foraging behaviour.

    Science.gov (United States)

    McNickle, Gordon G; Brown, Joel S

    2014-10-22

    Plants are adept at assessing and responding to nutrients in soil, and generally proliferate roots into nutrient-rich patches. An analogy between this growth response and animal foraging movement is often drawn, but because of differences between plants and animals it has not always been clear how to directly apply existing foraging theory to plants. Here we suggest one way to unite pre-existing ideas in plant nutrient uptake with foraging theory. First, we show that the Michaelis-Menten equation used by botanists and the Holling disc equation used by zoologists are actually just rearrangements of the same functional response. This mathematical unity permits the translation of existing knowledge about the nutrient uptake physiology of plants into the language of foraging behaviour, and as a result gives botanists direct access to foraging theory. Second, we developed a model of root foraging precision based on the Holling disc equation and the marginal value theorem, and parameterize it from the literature. The model predicts (i) generally plants should invest in higher quality patches compared to lower quality patches, and as patch background-contrast increases; (ii) low encounter rates between roots and nutrients result in high root foraging precision; and (iii) low handling times for nutrients should result in high root foraging precision. The available data qualitatively support these predictions. Third, to parameterize the model above we undertook a review of the literature. From that review we obtained parameter estimates for nitrate and/or ammonium uptake for 45 plant species from 38 studies. We observe that the parameters ranged over six orders of magnitude, there was no trade-off in foraging ability for nitrate versus ammonium: plants that were efficient foragers for one form of nitrogen were efficient foragers for the other, and there was also no phylogenetic signal in the parameter estimates. Published by Oxford University Press on behalf of the Annals

  11. Systematic review of the influence of foraging habitat on red-cockaded woodpecker reproductive success.

    Energy Technology Data Exchange (ETDEWEB)

    Garabedian, James E. [North Carolina State University

    2014-04-01

    Relationships between foraging habitat and reproductive success provide compelling evidence of the contribution of specific vegetative features to foraging habitat quality, a potentially limiting factor for many animal populations. For example, foraging habitat quality likely will gain importance in the recovery of the threatened red-cockaded woodpecker Picoides borealis (RCW) in the USA as immediate nesting constraints are mitigated. Several researchers have characterized resource selection by foraging RCWs, but emerging research linking reproductive success (e.g. clutch size, nestling and fledgling production, and group size) and foraging habitat features has yet to be synthesized. Therefore, we reviewed peer-refereed scientific literature and technical resources (e.g. books, symposia proceedings, and technical reports) that examined RCW foraging ecology, foraging habitat, or demography to evaluate evidence for effects of the key foraging habitat features described in the species’ recovery plan on group reproductive success. Fitness-based habitat models suggest foraging habitat with low to intermediate pine Pinus spp. densities, presence of large and old pines, minimal midstory development, and herbaceous groundcover support more productive RCW groups. However, the relationships between some foraging habitat features and RCW reproductive success are not well supported by empirical data. In addition, few regression models account for > 30% of variation in reproductive success, and unstandardized multiple and simple linear regression coefficient estimates typically range from -0.100 to 0.100, suggesting ancillary variables and perhaps indirect mechanisms influence reproductive success. These findings suggest additional research is needed to address uncertainty in relationships between foraging habitat features and RCW reproductive success and in the mechanisms underlying those relationships.

  12. Foraging activity rhythms of Dinoponera quadriceps (Hymenoptera: Formicidae) in its natural environment.

    Science.gov (United States)

    Medeiros, Jeniffer; Azevedo, Dina L O; Santana, Melquisedec A D; Lopes, Talita R P; Araújo, Arrilton

    2014-01-01

    This study characterizes the foraging activity of the queenless ant Dinoponera quadriceps (Kempf) (Hymenoptera: Formicidae) in its natural environment by testing the hypotheses that foraging activity presents both daily and seasonal rhythmic variations, and that these rhythms are related to environmental variables. Four colonies of D. quadriceps were observed in an area of secondary Atlantic forest in northeastern Brazil. Data collection was performed over 72 h every three months during an annual cycle. Both daily and seasonal foraging activity rhythms of D. quadriceps colonies were related to environmental factors, but colony differences also explained part of foraging variations. Foraging activity of D. quadriceps colonies was predominantly diurnal independently of season. In the early dry season, the colonies had two activity peaks, one in the morning and another in the afternoon, with a decrease in foraging at midday; however, during the rest of the year, foraging activity was distributed more evenly throughout the daylight hours. The daily rhythm of foraging activity was likely determined by an endogenous circadian rhythm year-round, but in the dry season, temperature and relative humidity also influenced daily foraging activity, with a negative effect of temperature and a positive effect of relative humidity. On a seasonal scale, foraging activity peaked in the early dry season and suddenly declined at the end of this season, increasing again at the late rainy season. The seasonal rhythm of foraging was negatively related to relative humidity and positively related to prey availability. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  13. Behavioral suites mediate group-level foraging dynamics in communities of tropical stingless bees.

    Science.gov (United States)

    Lichtenberg, E M; Imperatriz-Fonseca, V L; Nieh, J C

    2010-02-01

    Competition for floral resources is a key force shaping pollinator communities, particularly among social bees. The ability of social bees to recruit nestmates for group foraging is hypothesized to be a major factor in their ability to dominate rich resources such as mass-flowering trees. We tested the role of group foraging in attaining dominance by stingless bees, eusocial tropical pollinators that exhibit high diversity in foraging strategies. We provide the first experimental evidence that meliponine group foraging strategies, large colony sizes and aggressive behavior form a suite of traits that enable colonies to improve dominance of rich resources. Using a diverse assemblage of Brazilian stingless bee species and an array of artificial "flowers" that provided a sucrose reward, we compared species' dominance and visitation under unrestricted foraging conditions and with experimental removal of group-foraging species. Dominance does not vary with individual body size, but rather with foraging group size. Species that recruit larger numbers of nestmates (Scaptotrigona aff. depilis, Trigona hyalinata, Trigona spinipes) dominated both numerically (high local abundance) and behaviorally (controlling feeders). Removal of group-foraging species increased feeding opportunities for solitary foragers (Frieseomelitta varia, Melipona quadrifasciata and Nannotrigona testaceicornis). Trigona hyalinata always dominated under unrestricted conditions. When this species was removed, T. spinipes or S. aff. depilis controlled feeders and limited visitation by solitary-foraging species. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00040-009-0055-8) contains supplementary material, which is available to authorized

  14. Bumble bee nest abundance, foraging distance, and host-plant reproduction: implications for management and conservation.

    Science.gov (United States)

    Geib, Jennifer C; Strange, James P; Galenj, Candace

    2015-04-01

    Recent reports of global declines in pollinator species imply an urgent need to assess the abundance of native pollinators and density-dependent benefits for linked plants. In this study, we investigated (1) pollinator nest distributions and estimated colony abundances, (2) the relationship between abundances of foraging workers and the number of nests they represent, (3) pollinator foraging ranges, and (4) the relationship between pollinator abundance and plant reproduction. We examined these questions in an alpine ecosystem in the Colorado Rocky Mountains, focusing on four alpine bumble bee species (Bombus balteatus, B. flavifrons, B. bifarius, and B. sylvicola), and two host plants that differ in their degrees of pollinator specialization (Trifolium dasyphyllum and T. parryi). Using microsatellites, we found that estimated colony abundances among Bombus species ranged from ~18 to 78 colonies/0.01 km2. The long-tongued species B. balteatus was most common, especially high above treeline, but the subalpine species B. bifarius was unexpectedly abundant for this elevation range. Nests detected among sampled foragers of each species were correlated with the number of foragers caught. Foraging ranges were smaller than expected for all Bombus species, ranging from 25 to 110 m. Fruit set for the specialized plant, Trifolium parryi, was positively related to the abundance of its Bombus pollinator. In contrast, fruit set for the generalized plant, T. dasyphyllum, was related to abundance of all Bombus species. Because forager abundance was related to nest abundance of each Bombus species and was an equally effective predictor of plant fecundity, forager inventories are probably suitable for assessing the health of outcrossing plant populations. However, nest abundance, rather than forager abundance, better reflects demographic and genetic health in populations of eusocial pollinators such as bumble bees. Development of models incorporating the parameters we have measured

  15. Effects of forage:concentrate ratio and forage type on apparent digestibility, ruminal fermentation, and microbial growth in goats.

    Science.gov (United States)

    Cantalapiedra-Hijar, G; Yáñez-Ruiz, D R; Martín-García, A I; Molina-Alcaide, E

    2009-02-01

    The effects of forage type and forage:concentrate ratio (F:C) on apparent nutrient digestibility, ruminal fermentation, and microbial growth were investigated in goats. A comparison between liquid (LAB) and solid (SAB)-associated bacteria to estimate microbial N flow (MNF) from urinary purine derivative excretion was also examined. Treatments were a 2 x 2 factorial arrangement of forage type (grass hay vs. alfalfa hay) and high vs. low F:C (70:30 and 30:70, respectively). Four ruminally cannulated goats were fed, at maintenance intake, 4 experimental diets according to a 4 x 4 Latin square design. High-concentrate diets resulted in greater (P diets including grass hay. Likewise, N retention, ruminal NH(3)-N concentration, and urinary excretion of purine derivatives increased (P diets based on grass hay (0.23 vs. 0.13 g of retained N/g of digested N, 30.1 vs. 12.9 mg of NH(3)-N/100 mL, and 11.5 vs. 8.40 mmol/d, respectively), but not (P > 0.05) when diets included alfalfa hay. Total protozoa numbers and holotricha proportion were greater and less (P diets. The F:C affected (P diets. Estimated MNF was strongly influenced by using either the purine bases:N ratio obtained in our experimental conditions or values reported in the literature for small ruminants. There was a F:C effect (P = 0.006) on MNF estimated from LAB but not from SAB. The effect of F:C shifting from 70:30 to 30:70 in goat diets depends on the type of forage used. The MNF measured in goats fed different diets was influenced by the bacterial pellet (LAB or SAB). In addition, the purine bases:N ratio values found were different from those reported in the literature, which underlines the need for these variables to be analyzed directly in pellets isolated from specific animals and experimental conditions.

  16. Germinative potential of encrusted seed of tropical forage species

    Directory of Open Access Journals (Sweden)

    José Rafael de Souza

    Full Text Available ABSTRACT: Brazil is the largest producer, consumer and exporter of seeds of forage species, thus the adoption of new technologies for expansion and maintenance of this market is of great importance. The aim of this work was to evaluate encrustation effect on germination potential in seeds of Brachiaria sp. species. The experiment was carried out in Biofabrica laboratory from June to August 2014, in Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista-BA. The experimental design was completely randomized, in a factorial scheme 6x2, with two treatments (with and without coating and four replications. For germination quality of seeds were evaluated germination and vigor (emergence, emergence speed index, total length of seedling, shoot and root. The encrustation affected positively the germination of seeds in all species tested and encrustation did not affect the total length, shoot and root of the seedlings. Coating after chemical scarification is an alternative to improve germination of the seeds of tropical forage species.

  17. Foraging Path-length Protocol for Drosophila melanogaster Larvae.

    Science.gov (United States)

    Anreiter, Ina; Vasquez, Oscar E; Allen, Aaron M; Sokolowski, Marla B

    2016-04-23

    The Drosophila melanogaster larval path-length phenotype is an established measure used to study the genetic and environmental contributions to behavioral variation. The larval path-length assay was developed to measure individual differences in foraging behavior that were later linked to the foraging gene. Larval path-length is an easily scored trait that facilitates the collection of large sample sizes, at minimal cost, for genetic screens. Here we provide a detailed description of the current protocol for the larval path-length assay first used by Sokolowski. The protocol details how to reproducibly handle test animals, perform the behavioral assay and analyze the data. An example of how the assay can be used to measure behavioral plasticity in response to environmental change, by manipulating feeding environment prior to performing the assay, is also provided. Finally, appropriate test design as well as environmental factors that can modify larval path-length such as food quality, developmental age and day effects are discussed.

  18. Insect-foraging in captive owl monkeys (Aotus nancymaae).

    Science.gov (United States)

    Wolovich, Christy K; Rivera, Jeanette; Evans, Sian

    2010-08-01

    Whereas the diets of diurnal primate species vary greatly, almost all nocturnal primate species consume insects. Insect-foraging has been described in nocturnal prosimians but has not been investigated in owl monkeys (Aotus spp.). We studied 35 captive owl monkeys (Aotus nancymaae) in order to describe their foraging behavior and to determine if there were any age or sex differences in their ability to capture insect prey. Because owl monkeys cooperate in parental care and in food-sharing, we expected social interactions involving insect prey. We found that owl monkeys most often snatched flying insects from the air and immobilized crawling insects against a substrate using their hands. Immatures and adult female owl monkeys attempted to capture prey significantly more often than did adult males; however, there was no difference in the proportion of attempts that resulted in capture. Social interactions involving prey appeared similar to those with provisioned food, but possessors of prey resisted begging attempts more so than did possessors of other food. Owl monkeys attempted to capture prey often (mean = 9.5 +/- 5.8 attempts/h), and we speculate that the protein and lipid content of captured prey is important for meeting the metabolic demands for growth and reproduction.

  19. Nitrogen use efficiency in forage yield of tropical maize populations

    Directory of Open Access Journals (Sweden)

    Leandro Lopes Cancellier

    2014-06-01

    Full Text Available The development of adapted cultivars to nitrogen stress conditions is shown as an ecologically sustainable option to ensure higher yields in low input agricultural systems. This study aimed to evaluate the NUE in tropical maize (Zea mays L. populations to forage production in the south of the State of Tocantins. Two experiments were done corresponding to low and high N availability sown on November 21, 2009. Twenty four maize populations and a commercial cultivar BR 106 were used in the experiments. The experimental design was a randomized block with two replicates. Plant height, ear height, ear participation in plant total green mass, ear green mass; plant green mass without ear, total green mass and NUE in forage production were evaluated. Through Moll methodology differences among populations for nitrogen use efficiency were found, however these differences weren’t found on Fischer methodology. Populations 12-4, 1-3, 12-6, 12-5, 26-1, 15-2, 25-2 and 1-5 are considered efficient in nitrogen use. The populations 12-6, 12-5, 12-4, 1-3, 1-4, 1-5 and 15-2 are the best populations to use in high and low N environment, combining great production of green mass and being efficient in N use.

  20. Error in the honeybee waggle dance improves foraging flexibility.

    Science.gov (United States)

    Okada, Ryuichi; Ikeno, Hidetoshi; Kimura, Toshifumi; Ohashi, Mizue; Aonuma, Hitoshi; Ito, Etsuro

    2014-02-26

    The honeybee waggle dance communicates the location of profitable food sources, usually with a certain degree of error in the directional information ranging from 10-15° at the lower margin. We simulated one-day colonial foraging to address the biological significance of information error in the waggle dance. When the error was 30° or larger, the waggle dance was not beneficial. If the error was 15°, the waggle dance was beneficial when the food sources were scarce. When the error was 10° or smaller, the waggle dance was beneficial under all the conditions tested. Our simulation also showed that precise information (0-5° error) yielded great success in finding feeders, but also caused failures at finding new feeders, i.e., a high-risk high-return strategy. The observation that actual bees perform the waggle dance with an error of 10-15° might reflect, at least in part, the maintenance of a successful yet risky foraging trade-off.

  1. Role of depletion on the dynamics of a diffusing forager

    Science.gov (United States)

    Bénichou, O.; Chupeau, M.; Redner, S.

    2016-09-01

    We study the dynamics of a starving random walk in general spatial dimension d. This model represents an idealized description for the fate of an unaware forager whose motion is not affected by the presence or absence of resources. The forager depletes its environment by consuming resources and dies if it wanders too long without finding food. In the exactly solvable case of one dimension, we explicitly derive the average lifetime of the walk and the distribution for the number of distinct sites visited by the walk at the instant of starvation. We also give a heuristic derivation for the averages of these two quantities. We tackle the complex but ecologically relevant case of two dimensions by an approximation in which the depleted zone is assumed to always be circular and which grows incrementally each time the walk reaches the edge of this zone. Within this framework, we derive a lower bound for the scaling of the average lifetime and number of distinct sites visited at starvation. We also determine the asymptotic distribution of the number of distinct sites visited at starvation. Finally, we solve the case of high spatial dimensions within a mean-field approach.

  2. Energetics of foraging and locomotion in the platypus Ornithorhynchus anatinus.

    Science.gov (United States)

    Bethge, P; Munks, S; Nicol, S

    2001-08-01

    We measured the energy requirements of platypuses foraging, diving and resting in a swim tank using flow-through respirometry. Also, walking metabolic rates were obtained from platypuses walking on a conventional treadmill. Energy requirements while foraging were found to depend on water temperature, body weight and dive duration and averaged 8.48 W kg(-1). Rates for subsurface swimming averaged 6.71 W kg(-1). Minimal cost of transport for subsurface swimming platypuses was 1.85 J N(-1)m(-1) at a speed of 0.4 m s(-1). Aerobic dive limit of the platypus amounted to 59 s. Metabolic rate of platypuses resting on the water surface was minimal with 3.91 W kg(-1) while minimal RMR on land was 2.08 W kg(-1). The metabolic rate for walking was 8.80 W kg(-1) and 10.56 W kg(-1) at speeds of 0.2 m s(-1) and 0.3 m s(-1), respectively. A formula was derived, which allows prediction of power requirements of platypuses in the wild from measurements of body weight, dive duration and water temperature. Platypuses were found to expend energy at only half the rate of semiaquatic eutherians of comparable body sizes during both walking and diving. However, costs of transport at optimal speed were in line with findings for eutherians. These patterns suggest that underwater locomotion of semiaquatic mammals have converged on very similar efficiencies despite differences in phylogeny and locomotor mode.

  3. Theory of choice in bandit, information sampling and foraging tasks.

    Science.gov (United States)

    Averbeck, Bruno B

    2015-03-01

    Decision making has been studied with a wide array of tasks. Here we examine the theoretical structure of bandit, information sampling and foraging tasks. These tasks move beyond tasks where the choice in the current trial does not affect future expected rewards. We have modeled these tasks using Markov decision processes (MDPs). MDPs provide a general framework for modeling tasks in which decisions affect the information on which future choices will be made. Under the assumption that agents are maximizing expected rewards, MDPs provide normative solutions. We find that all three classes of tasks pose choices among actions which trade-off immediate and future expected rewards. The tasks drive these trade-offs in unique ways, however. For bandit and information sampling tasks, increasing uncertainty or the time horizon shifts value to actions that pay-off in the future. Correspondingly, decreasing uncertainty increases the relative value of actions that pay-off immediately. For foraging tasks the time-horizon plays the dominant role, as choices do not affect future uncertainty in these tasks.

  4. MORPHOLOGICAL AND PRODUCTIVE CHARACTERIZATION OF FORAGE CACTUS VARIETIES

    Directory of Open Access Journals (Sweden)

    PHILIPE LIMA DE AMORIM

    2015-01-01

    Full Text Available Cultivars of the genus Nopalea are known in Brazil for being tolerant to cochineal carmine attacks, thus making the cultivation of this genus a promising alternative for mitigating the negative effects of this insect on the production of biomass. With the objectives of characterizing morphologically spineless forage cactus varieties and identify morphological characteristics that may be the focus in spineless forage cactus breeding programs, an experiment was conducted in a completely randomized block design with 11 treatments and four replications. The variety Alagoas showed the highest values of weight, area and volume of cladodes. The varieties Negro Michoacan F7 and V7, Tamazunchale V12 showed the highest values of the cladode area index, the total volume of cladodes and total fresh mass production. The varieties Negro Michoacan V7 and F7 presented the highest water use efficiency and dry mass yield. Cladode volume showed the highest correlation coefficients with the fresh weight of cladodes. Aiming the release of varieties for biomass production, varieties Negro Michoacan F7, V7 and Tamazunchale V12 may substitute the Miúda variety. The number and cladode area index may be used as criteria for selection of superior varieties in breeding programs.

  5. Memory Effects on Movement Behavior in Animal Foraging.

    Directory of Open Access Journals (Sweden)

    Chloe Bracis

    Full Text Available An individual's choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk. We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.

  6. Memory Effects on Movement Behavior in Animal Foraging.

    Science.gov (United States)

    Bracis, Chloe; Gurarie, Eliezer; Van Moorter, Bram; Goodwin, R Andrew

    2015-01-01

    An individual's choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.

  7. Identifying Winter Forage Triticale (X Triticosecale Wittmack) Strains for the Central Great Plains

    Science.gov (United States)

    Triticale (X Triticosecale Wittmack), a human-made crop, is mainly used as a forage crop in the central Great Plains. A successful triticale cultivar should have high forage yield with good quality, and also high grain yield so the seed can be economically produced. Hence, the purpose of this study...

  8. Effect of species and harvest maturity on the fatty acids profile of tropical forages

    NARCIS (Netherlands)

    Khan, N.A.; Farooq, M.W.; Ali, M.; Suleman, M.; Ahmad, N.; Sulaiman, S.M.; Cone, J.W.; Hendriks, W.H.

    2015-01-01

    The aim of this study was to quantify the fatty acid (FA) content and composition of forages commonly fed to dairy animals in the tropics. Twelve forage species, namely, Trifolium alexandrinum, Cichorium intybus, Hordeum vulgare L., Medicago sativa, Avena sativa, Pennisetum purpureum Setaria anceps,

  9. Annual variation in foraging ecology of prothonotary warblers during the breeding season

    Science.gov (United States)

    Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J.

    1990-01-01

    We studied foraging ecology of Prothonotary Warblers (Protonotaria citrea) along the Tennessee River in west-central Tennessee during the breeding seasons of 1984-1987. We analyzed seven foraging variables to determine if this population exhibited annual variation in foraging behavior. Based on nearly 3,000 foraging maneuvers, most variables showed significant interyear variation during the four prenestling and three nestling periods we studied. This interyear variation probably was due -to proximate, environmental cues--such as distribution and abundance of arthropods--which, in turn, were influenced by local weather conditions. Researchers should consider the consequences of combining foraging behavior data collected in different years, because resolution of ecological trends may be sacrificed by considering only general patterns of foraging ecology and not the dynamics of those activities. In addition, because of annual variability, foraging data collected in only one year, regardless of the number of observations gathered, may not provide an accurate concept of the foraging ecology in insectivorous birds.

  10. Linkage between fishes'foraging, market and fish stocks density: Examples from some North Sea fisheries

    NARCIS (Netherlands)

    Marchal, P.; Poos, J.J.; Quirijns, F.J.

    2007-01-01

    This study has investigated some properties of fishermen's foraging, using Levy flights theory. The case studies examined were a selection of North Sea Dutch and French vessels, for which catch and effort data were collected on a haul-by-haul basis. Foraging behavior could reasonably be represented

  11. Annual warm-season grasses vary for forage yield, quality, and competitiveness with weeds

    Science.gov (United States)

    Warm-season annual grasses may be suitable as herbicide-free forage crops. A two-year field study was conducted to determine whether tillage system and nitrogen (N) fertilizer application method influenced crop and weed biomass, water use, water use efficiency (WUE), and forage quality of three war...

  12. Untying the knot: mechanistically understanding the interactions between social foragers and their prey

    NARCIS (Netherlands)

    Bijleveld, A.I.

    2015-01-01

    An entire flyway of shorebirds is dependent on the Dutch Wadden Sea. Here they find food to survive or fuel their flights towards the Arctic or Africa. Most shorebirds feed on worms and shellfish hiding in the mud. The work presented in this thesis concerns the foraging decisions of a socially forag

  13. Moving on with foraging theory: incorporating movement decisions into the functional response of a gregarious shorebird

    NARCIS (Netherlands)

    van Gils, J.A.; van der Geest, M.; De Meulenaer, B.; Gillis, H.; Piersma, T.; Folmer, E.O.

    2015-01-01

    1.Models relating intake rate to food abundance and competitor density (generalized functional response models) can predict forager distributions and movements between patches, but we lack understanding of how distributions and small-scale movements by the foragers themselves affect intake rates.2.U

  14. Moving on with foraging theory : Incorporating movement decisions into the functional response of a gregarious shorebird

    NARCIS (Netherlands)

    van Gils, Jan A; van der Geest, Matthijs; De Meulenaer, Brecht; Gillis, Hanneke; Piersma, Theunis; Folmer, Eelke O

    2015-01-01

    Models relating intake rate to food abundance and competitor density (generalized functional response models) can predict forager distributions and movements between patches, but we lack understanding of how distributions and small-scale movements by the foragers themselves affect intake rates. Usin

  15. Dry season mapping of savanna forage quality, using the hyperspectral Carnegie

    NARCIS (Netherlands)

    Knox, N.; Skidmore, A.K.; Prins, H.H.T.; Asner, P.; Werff, van der H.M.A.; Boer, de W.F.; Waal, van der C.; Knegt, de H.J.; Kohi, E.; Slotow, R.; Grant, R.C.

    2011-01-01

    Forage quality within an African savanna depends upon limiting nutrients (nitrogen and phosphorus) and nutrients that constrain the intake rates (non-digestible fibre) of herbivores. These forage quality nutrients are particularly crucial in the dry season when concentrations of limiting nutrients d

  16. The evolution of foraging rate across local and geographic gradients in predation risk and competition.

    Science.gov (United States)

    Urban, Mark C; Richardson, Jonathan L

    2015-07-01

    Multiple theories predict the evolution of foraging rates in response to environmental variation in predation risk, intraspecific competition, time constraints, and temperature. We tested six hypotheses for the evolution of foraging rate in 24 spotted salamander (Ambystoma maculatum) populations from three latitudinally divergent sites using structural equation models derived from theory and applied to our system. We raised salamander larvae in a common-garden experiment and then assayed foraging rate under controlled conditions. Gape-limited predation risk from marbled salamanders solely explained foraging rate variation among populations at the southern site, which was dominated by this form of selection. However, at the middle and northern sites, populations evolved different foraging rates depending on their unique responses to local intraspecific density. The coupling of gape-limited predation risk from marbled salamanders and high intraspecific density at the middle site jointly contributed to selection for rapid foraging rate. At the northernmost site, intraspecific density alone explained 97% of the interpopulation variation in foraging rate. These results suggest that foraging rate has evolved multiple times in response to varying contributions from predation risk and intraspecific competition. Predation risk often varies along environmental gradients, and, thus, organisms might often shift evolutionary responses from minimizing predation risk to maximizing intraspecific competitive performance.

  17. Patch densities determines movement patterns and foraging efficiency of large herbivores

    NARCIS (Netherlands)

    Knegt, de H.J.; Hengeveld, G.M.; Langevelde, van F.; Boer, de W.F.; Kirkman, K.P.

    2007-01-01

    Few experimental studies have tested theoretical predictions regarding the movement strategies of large herbivores and their consequences for foraging efficiency. We therefore analyze how the movement and foraging behavior of goats are related to patch density, with patches being trees and bushes. W

  18. Anaerobic co-digestion of forage radish and dairy manure in complete mix digesters

    Science.gov (United States)

    Farmers are increasingly using forage radish as a winter cover crop to achieve multiple soil and environmental benefits. In this study, pilot-scale mixed digesters were used to quantify methane (CH4) and hydrogen sulfide (H2S) production when using forage radish, a sulfur-rich cover crop, as a co-d...

  19. Snag Condition and Woodpecker Foraging Ecology in a Bottomland Hardwood Forest

    Science.gov (United States)

    Richard N. Conner; Stanley D. Jones; Gretchen D. Jones

    1994-01-01

    We studied woodpecker foraging behavior, snag quality, and surrounding habitat in a bottomland hardwood forest in the Stephen F. Austin Experimental Forest from December 1984 through November 1986. The amount and location of woodpecker foraging excavations indicated that woodpeckers excavated mainly at the well-decayed tops and bases of snags. Woodpeckers preferred to...

  20. Fermentation kinetics of two intercropped forages cut at different growth stage

    Directory of Open Access Journals (Sweden)

    F. Infascelli

    2010-01-01

    Full Text Available The mixture legume/grass determines agronomic advantages (i.e. lower N fertilization and more equilibrate energy/N ratio in the forage for ruminant (Betti et al., 1992. In South of Italy, the most utilized intercropped forages are barley-fava bean and vetch-oats due to the particular climatic conditions.

  1. Foraging recruitment by the Giant Tropical Ant Paraponera clavata (Hymenoptera, Formicidae)

    Science.gov (United States)

    Barrett, Bruce A.; Jorgenson, Clive D.; Looman, Sandra J.

    1985-01-01

    Increased foraging of an exceptionally abundant, but ephemeral, food source by ants can result from foraging excitement that does not include pheromone trails, tandem running, or from recruitment of other workers along pheromone trails (Carrol and Janzen, 1973). They also provided rationale for two types of short-lived pheromone trails resulting in mass or group recruitment. These both seem to fall into the Type II foraging strategy described by Oster and Wilson (1978). Neither of these discussions conveniently allow for pheromone recruitment by relatively small colonies of a primitive monomorphic species such as Paraponera clavata. Our observations suggest that recruitment to an abundant ephemeral food source does occur naturally and can be induced artificially in colonies of P. clavata.Paraponera clavata is considered primitive (Wilson, 1958), particularly in foraging habits (Young and Hermann, 1980; Young, 1977). Hermann (1973, 1975) reported the P. clavata, unlike more advanced species, forages independently; following shot periods of apparent group activity outside of the colony (Young and Hermann, 1980). It reportedly does not return to a food source when only part has been harvested. After returning to its colony with booty, a single worker resumes foraging independently, with no observable tendency to return to partially harvested booty or without recruiting additional workers to collect the remaining food (Hermann, 1973; Young and Hermann, 1980). Reports of independent foraging, lack of forager recruitment, and apparent lack of food source fidelity resulted in the assumption that P. clavata probably lacks an effective pheromone trail communication system (Young and Hermann, 1980).

  2. The rewards of restraint in the collective regulation of foraging by harvester ant colonies.

    Science.gov (United States)

    Gordon, Deborah M

    2013-06-06

    Collective behaviour, arising from local interactions, allows groups to respond to changing conditions. Long-term studies have shown that the traits of individual mammals and birds are associated with their reproductive success, but little is known about the evolutionary ecology of collective behaviour in natural populations. An ant colony operates without central control, regulating its activity through a network of local interactions. This work shows that variation among harvester ant (Pogonomyrmex barbatus) colonies in collective response to changing conditions is related to variation in colony lifetime reproductive success in the production of offspring colonies. Desiccation costs are high for harvester ants foraging in the desert. More successful colonies tend to forage less when conditions are dry, and show relatively stable foraging activity when conditions are more humid. Restraint from foraging does not compromise a colony's long-term survival; colonies that fail to forage at all on many days survive as long, over the colony's 20-30-year lifespan, as those that forage more regularly. Sensitivity to conditions in which to reduce foraging activity may be transmissible from parent to offspring colony. These results indicate that natural selection is shaping the collective behaviour that regulates foraging activity, and that the selection pressure, related to climate, may grow stronger if the current drought in their habitat persists.

  3. Foraging Activity Pattern Is Shaped by Water Loss Rates in a Diurnal Desert Rodent.

    Science.gov (United States)

    Levy, Ofir; Dayan, Tamar; Porter, Warren P; Kronfeld-Schor, Noga

    2016-08-01

    Although animals fine-tune their activity to avoid excess heat, we still lack a mechanistic understanding of such behaviors. As the global climate changes, such understanding is particularly important for projecting shifts in the activity patterns of populations and communities. We studied how foraging decisions vary with biotic and abiotic pressures. By tracking the foraging behavior of diurnal desert spiny mice in their natural habitat and estimating the energy and water costs and benefits of foraging, we asked how risk management and thermoregulatory requirements affect foraging decisions. We found that water requirements had the strongest effect on the observed foraging decisions. In their arid environment, mice often lose water while foraging for seeds and cease foraging even at high energetic returns when water loss is high. Mice also foraged more often when energy expenditure was high and for longer times under high seed densities and low predation risks. Gaining insight into both energy and water balance will be crucial to understanding the forces exerted by changing climatic conditions on animal energetics, behavior, and ecology.

  4. Small is profitable: No support for the optimal foraging theory in sea stars

    NARCIS (Netherlands)

    Hummel, C.; Honkoop, P.; van der Meer, J.

    2011-01-01

    Doubt has been shed recently on the most popular optimal foraging theory stating that predators should maximize prey profitability, i.e., select that prey item that contains the highest energy content per handling time. We hypothesized that sea stars do not forage on blue mussels according to the cl

  5. Foraging behavior and physiological changes in precocial quail chicks in response to low temperatures

    NARCIS (Netherlands)

    Krijgsveld, KL; Visser, GH; Daan, S

    2003-01-01

    We examined whether low ambient temperatures influence foraging behavior of precocial Japanese quail chicks and alter the balance between investment in growth and thermogenic function. To test this, one group of chicks was exposed to 7 degreesC and one group to 24 degreesC during foraging throughout

  6. Combined foraging strategies and soldier behaviour in Nasutitermes aff. coxipoensis (Blattodea: Termitoidea: Termitidae).

    Science.gov (United States)

    Almeida, Camilla S; Cristaldo, Paulo F; Florencio, Daniela F; Cruz, Nayara G; Santos, Abraão A; Oliveira, Alexandre P; Santana, Alisson S; Ribeiro, Efrem J M; Lima, Ana P S; Bacci, Leandro; Araújo, Ana P A

    2016-05-01

    A range of behavioural strategies and sensory abilities allows animals to minimize costs involved in food search. By building a network of tunnels and presenting a large number of soldiers (i.e., trophically dependent individuals), Nasutitermes spp. termites feature behaviours that imply additional costs during this process. Here we evaluated N. aff. coxipoensis foraging strategies focusing on the role of soldiers during foraging. Field experiments were carried out via nests transplantation to dune areas, and laboratory experiments evaluated termite responses to sternal gland chemical signals from workers and soldiers. N. aff. coxipoensis presented primarily nocturnal foraging. Soldiers typically initiated foraging; however, in established trails, the number of workers was always higher than that of soldiers. The number of trails remained constant over time, while the number of tunnels increased linearly over time. A higher proportion of tunnels originated in surrounding areas than directly from the nests. At observation points with tunnels, there were more stationary than walking soldiers; the opposite was true at observation points without tunnels. In mixed groups, the workers chose to follow soldier chemical signals, and in these groups, soldiers were the first to follow trails. Our results allowed us to identify a not common foraging strategy in termite species; which included the establishment of trails followed by construction of tunnels. Such foraging strategies occur predominantly at night and soldiers play a key role in the foraging process. This foraging strategy reported here seems to be employed to optimize energetic gain.

  7. Assessing herbivore foraging behavior with GPS collars in a semiarid grassland

    Science.gov (United States)

    Advances in global positioning system (GPS) technology have dramatically enhanced the ability to track and study distributions of free-ranging livestock. However, understanding factors controlling livestock foraging distribution requires the ability to assess when and where they are foraging. We col...

  8. Information from familiar and related conspecifics affects foraging in a solitary wolf spider.

    Science.gov (United States)

    Hoffman, Catherine R; Sitvarin, Michael I; Rypstra, Ann L

    2016-06-01

    As neighbours become familiar with one another, they can divert attention away from one another and focus on other activities. Since familiarity is a likely mechanism by which animals recognise relatives, both kinship and prior association with conspecifics should allow individuals to increase foraging. We attempted to determine if the interference observed among conspecific foragers could be mitigated by familiarity and/or kinship. Because Pardosa milvina wolf spiders are sensitive to chemotactile cues deposited on substrates by other spiders, we used cues to manipulate the information available to focal spiders. We first verified that animals could use these cues to differentiate relatives and familiar conspecifics. We then documented foraging in the presence of all combinations of related and familiar animal cues. Test spiders were slower foragers, less likely to capture prey, and consumed less of each prey item when on cues from unfamiliar kin, but were faster and more effective foragers on cues from familiar non-kin. Their reactions to familiar kin and unfamiliar non-kin were intermediate. High foraging intensity on familiar cues is consistent with the idea that animals pay less attention to neighbours after some prior association. Lower foraging effort in the presence of cues from relatives may be an attempt to reduce kin competition by shifting attention toward dispersal or to provide increased access to prey for hungry relatives nearby. These findings reveal that information from conspecifics mediates social interactions among individuals and affects foraging in ways that can influence their role in the food web.

  9. The foraging benefits of being fat in a highly migratory marine mammal.

    Science.gov (United States)

    Adachi, Taiki; Maresh, Jennifer L; Robinson, Patrick W; Peterson, Sarah H; Costa, Daniel P; Naito, Yasuhiko; Watanabe, Yuuki Y; Takahashi, Akinori

    2014-12-22

    Foraging theory predicts that breath-hold divers adjust the time spent foraging at depth relative to the energetic cost of swimming, which varies with buoyancy (body density). However, the buoyancy of diving animals varies as a function of their body condition, and the effects of these changes on swimming costs and foraging behaviour have been poorly examined. A novel animal-borne accelerometer was developed that recorded the number of flipper strokes, which allowed us to monitor the number of strokes per metre swam (hereafter, referred to as strokes-per-metre) by female northern elephant seals over their months-long, oceanic foraging migrations. As negatively buoyant seals increased their fat stores and buoyancy, the strokes-per-metre increased slightly in the buoyancy-aided direction (descending), but decreased significantly in the buoyancy-hindered direction (ascending), with associated changes in swim speed and gliding duration. Overall, the round-trip strokes-per-metre decreased and reached a minimum value when seals achieved neutral buoyancy. Consistent with foraging theory, seals stayed longer at foraging depths when their round-trip strokes-per-metre was less. Therefore, neutrally buoyant divers gained an energetic advantage via reduced swimming costs, which resulted in an increase in time spent foraging at depth, suggesting a foraging benefit of being fat.

  10. Behavioural responses of Eastern grey squirrels, Sciurus carolinensis, to cues of risk while foraging.

    Science.gov (United States)

    Jayne, Kimberley; Lea, Stephen E G; Leaver, Lisa A

    2015-07-01

    Previous studies have shown that Eastern grey squirrels modify their behaviour while foraging to offset risks of social and predatory costs, but none have simultaneously compared whether such modifications are performed at a cost to foraging. The present study directly compares how grey squirrels respond to cues of these risks while foraging. We simulated social risk and predatory risk using acoustic playbacks of stimuli that grey squirrels might be exposed to at a foraging patch: calls of conspecifics, heterospecifics (competitor and non-competitor) and predators. We found that grey squirrels responded to predator, heterospecific competitor and conspecific playbacks by altering their foraging and vigilance behaviours. Foraging was most disrupted by increased vigilance when we played calls of predators. Squirrels' response to calls of heterospecific competitors did not differ from their response to conspecific calls, and they resumed foraging more quickly after both compared to predator calls: whereas they showed little response to calls of non-competitor heterospecifics and a white noise control. We conclude that squirrels respond differentially to calls made by conspecifics, heterospecific competitors and predators, with the most pronounced response being to calls of predators. We suggest that squirrels may view conspecific and corvid vocalisations as cues of potential conflict while foraging, necessitating increased vigilance.

  11. Foraging innovation is inversely related to competitive ability in male but not in female guppies

    NARCIS (Netherlands)

    Laland, K.N.; Reader, S.M.

    1999-01-01

    Foraging success is likely to affect hunger level and motivation to locate and exploit novel food sources in animals. We explored the relationship between scramble competition for limited food and foraging innovation in the guppy (Poecilia reticulata), predicting that poor competitors would be more

  12. Quality of foraging material and the effect on hens feed intake, egg production and - quality

    DEFF Research Database (Denmark)

    Steenfeldt, Sanna; Hammershøj, Marianne

    2010-01-01

    In a project with organic egg laying hens, the effect of different kind of foraging material was studied on feed intake, egg-production and -quality. Udgivelsesdato: August......In a project with organic egg laying hens, the effect of different kind of foraging material was studied on feed intake, egg-production and -quality. Udgivelsesdato: August...

  13. Foraging innovation is inversely related to competitive ability in male but not in female guppies

    NARCIS (Netherlands)

    Laland, K.N.; Reader, S.M.

    1999-01-01

    Foraging success is likely to affect hunger level and motivation to locate and exploit novel food sources in animals. We explored the relationship between scramble competition for limited food and foraging innovation in the guppy (Poecilia reticulata), predicting that poor competitors would be more

  14. Foraging decisions in wild versus domestic Mus musculus: What does life in the lab select for?

    Science.gov (United States)

    Troxell-Smith, Sandra M; Tutka, Michal J; Albergo, Jessica M; Balu, Deebika; Brown, Joel S; Leonard, John P

    2016-01-01

    What does domestication select for in terms of foraging and anti-predator behaviors? We applied principles of patch use and foraging theory to test foraging strategies and fear responses of three strains of Mus musculus: wild-caught, control laboratory, and genetically modified strains. Foraging choices were quantified using giving-up densities (GUDs) under three foraging scenarios: (1) patches varying in microhabitat (covered versus open), and initial resource density (low versus high); (2) daily variation in auditory cues (aerial predators and control calls); (3) patches with varying seed aggregations. Overall, both domestic strains harvested significantly more food than wild mice. Each strain revealed a significant preference for foraging under cover compared to the open, and predator calls had no detectable effects on foraging. Both domestic strains biased their harvest toward high quality patches; wild mice did not. In terms of exploiting favorable and avoiding unfavorable distributions of seeds within patches, the lab strain performed best, the wild strain worst, and the mutant strain in between. Our study provides support for hypothesis that domestic animals have more energy-efficient foraging strategies than their wild counterparts, but retain residual fear responses. Furthermore, patch-use studies can reveal the aptitudes and priorities of both domestic and wild animals.

  15. Untying the knot: mechanistically understanding the interactions between social foragers and their prey

    NARCIS (Netherlands)

    Bijleveld, A.I.

    2015-01-01

    An entire flyway of shorebirds is dependent on the Dutch Wadden Sea. Here they find food to survive or fuel their flights towards the Arctic or Africa. Most shorebirds feed on worms and shellfish hiding in the mud. The work presented in this thesis concerns the foraging decisions of a socially forag

  16. Implications of Perennial Biomass Energy Cropping Systems for Pasture and Forage Lands

    Science.gov (United States)

    The lignocellulose in forage crops represents large source of biomass feedstock for conversion into energy-related end products. With new technologies and processes for biomass production and conversion approaching commercial reality forages could once again fuel agriculture. Some of the most extens...

  17. Improved forage strategies for high-yielding dairy cows in Vietnam : report of a workshop

    NARCIS (Netherlands)

    Wouters, A.P.; Lee, van der J.

    2013-01-01

    This report presents results of the workshop "Improved forage strategies for high-yielding dairy cows in Vietnam" which was held with Vietnamese stakeholders on January 17-18, 2013 in Ho Chi Minh City as part of the project "Forage and Grass Production for Dairy Development in Vietnam" funded by the

  18. N fertilization for improved forage yields has little impact on nutritive value

    Science.gov (United States)

    Applications of soil amendments or fertilizers containing nitrogen are a routine part of most grass forage management strategies, with the primary goal of improving forage yields. But an increase in yield is usually accompanied by a decrease in nutritive value. In order to better evaluate this trade...

  19. Effects of nitrogen fertilization on the nutritive value of oat forages

    Science.gov (United States)

    Nitrogen fertilization is a routine part of forage management strategies for grasses, but the effects on forage nutritive value have been inconsistent. Our objectives were to evaluate the effects of N fertilization on the nutritive value of fall-grown oat fertilized at planting with 20, 40, 60, 80, ...

  20. Southern Elephant Seals Replenish Their Lipid Reserves at Different Rates According to Foraging Habitat

    Science.gov (United States)

    Richard, Gaëtan; Cox, Samantha L.; Picard, Baptiste; Vacquié-Garcia, Jade; Guinet, Christophe

    2016-01-01

    Assessing energy gain and expenditure in free ranging marine predators is difficult. However, such measurements are critical if we are to understand how variation in foraging efficiency, and in turn individual body condition, is impacted by environmentally driven changes in prey abundance and/or accessibility. To investigate the influence of oceanographic habitat type on foraging efficiency, ten post-breeding female southern elephant seals Mirounga leonina (SES) were equipped and tracked with bio-loggers to give continuous information of prey catch attempts, body density and body activity. Variations in these indices of foraging efficiency were then compared between three different oceanographic habitats, delineated by the main frontal structures of the Southern Ocean. Results show that changes in body density are related not only to the number of previous prey catch attempts and to the body activity (at a 6 day lag), but also foraging habitat type. For example, despite a lower daily prey catch attempt rate, SESs foraging north of the sub-Antarctic front improve their body density at a higher rate than individuals foraging south of the sub-Antarctic and polar fronts, suggesting that they may forage on easier to catch and/or more energetically rich prey in this area. Our study highlights a need to understand the influence of habitat type on top predator foraging behaviour and efficiency when attempting a better comprehension of marine ecosystems. PMID:27902786