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Sample records for honeybeenet forage region

  1. Foraging

    NARCIS (Netherlands)

    Ydenberg, R.C.; Prins, H.H.T.

    2012-01-01

    This chapter describes the role played by behavioural adjustments to foraging behaviour in accommodating rapid environmental change. It looks into the adjustments of foraging behaviour to predation danger as a result of changes in the type and array of food available. It investigates the effects of

  2. 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.

  3. 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.

  4. Analysis of the potentiality haying of native forage species in semiarid region

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    Enoque de Sousa Leão

    2017-10-01

    Full Text Available The objective of this study was to evaluate the potential hay production from Spiny Amaranth (Amaranthus spinosus, Hairy Woodrose (Merremia aegyptia, Malva (Sida galheirensis, Mucuna (Mucuna pruriens and Ervanço (Froelichia humboldtiana, native forage species of the semiarid region of Brazil by observing morphological components of the plant, such as the dehydration curve, crude protein loss (CPL curve, chemical composition of plant and hay and hay degradability in situ. There were differences (P < 0.05 among species on leaf, stem and inflorescence quantification with Ervanço, Hairy Woodrose, and Mucuna having a greater number of leaves. There was a linearly increasing response for the dehydration curve of the five forage plants species. Mucuna forage had the greatest hay point at 800 g kg-1 dried matter (DM after 11.8 hours and Woodrose had a lower dehydration efficiency, which required 25 hours of sun exposure. There was no difference in CPL. Mucuna had the lowest crude protein (CP, neutral detergent fiber (NDF and acid detergent fiber (ADF content, 8.4, 67.7 and 73.8 g kg DM-1 in hay in relation to the plant, respectively. Ervanço, Spiny Amaranth, Hairy Woodrose and Malva hay had more of soluble fraction “a” of DM of 31.0, 26.2, 22.1 and 9.7 g kg-1 DM than Mucuna, respectively. Spiny Amaranth and Malva hay had values of 335.4 and 193.2 g kg-1 DM of fraction “b” more than Ervanço hay, respectively. For fraction “a’’ of CP, Spiny Amaranth and Hairy Woodrose hay obtained 312.6 and 227.4 g kg-1 CP more than that observed for Malva, respectively. Mucuna had better hay potential among the forage studied in the semiarid region of Brazil.

  5. 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.

  6. Identifying Hot Spots of Critical Forage Supply in Dryland Nomadic Pastoralist Areas: A Case Study for the Afar Region, Ethiopia

    NARCIS (Netherlands)

    Sonneveld, B.G.J.S.; Keyzer, M.A.; van Wesenbeeck, C.F.A.; Georgis, Kidane; Beyene, Fekadu; Urbano, Ferdinando; Meroni, Michele; Leo, Olivier; Yimer, Merkebu; Abdullatif, Mohammed

    2017-01-01

    This study develops a methodology to identify hot spots of critical forage supply in nomadic pastoralist areas, using the Afar Region, Ethiopia, as a special case. It addresses two main problems. First, it makes a spatially explicit assessment of fodder supply and demand extracted from a data poor

  7. Foraging on some nonfloral resources by stingless bees (Hymenoptera, Meliponini in a caatinga region

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    M. C. A. Lorenzon

    Full Text Available In a caatinga region the flowers and nonfloral resources visited by highly eusocial bees, stingless beess and Apis mellifera (Africanized honey bee were studied. During one year, monthly sampling took place in two sites at Serra da Capivara National Park (Piauí State, Brazil, one of them, including the local village, outside the park, and the other inside, using already existing park trails. With the help of entomological nets, all bees were caught while visiting floral and nonfloral resources. At the study sites we observed more stingless bees in nonfloral resources, made possible by human presence. Twelve stingless bee species used the nonfloral resources in different proportions, showing no preference for time of day, season of the year, or sites. During the rainy season, more water sources and abundant flowering plants were observed, which attract stingless bees, even though many worker bees were found foraging in the aqueous substrates while few were observed at water sources. This relationship was higher for stingless bee species than for Africanized honey bees. Paratrigona lineata was represented by few specimens in floral and nonfloral resources and is perhaps rare in this region. Frieseomelitta silvestrii could be considered rare in the floral resources, but they were abundant in nonfloral resources. The variety and intriguing abundance of bees in nonfloral resources suggests that these are an important part of the stingless bee niches, even if these resources are used for nest construction and defense.

  8. Composition of Mix Species Foraging Flocks of Birds in Riverstan of Montane Region, Sri Lanka

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    W.G.D.D.M. Shermila

    2013-04-01

    Full Text Available Montane zone mixed-species bird flock system is distinct from that of low-land wet zone of SriLanka, although some species are present in both systems. The present study identified the mixed speciesflocks of birds in Riverstan at Knuckles Region, Sri Lanka. Monthly transect counts and opportunisticobservations were made between January and May, 2012. A total of 78 flocks and 27 bird species wereencountered at Riverstan during the study period. The flock size varied between 2 to 13 species and 4 to58 individuals. The mean number of species per flock was 6.03 ± 2.25 and the mean number ofindividuals in a flock was 18.41±9.87. The flock size was positively correlated with the number of speciespresent (r = 0.756, P <0.05. Grey-headed Canary Flycatcher was the most abundant species (mean2.68±1.02 birds per flocks while Sri Lanka White-eye was the most frequent species (mean 5.69±3.92birds per flocks. Grey-headed Canary Flycatcher and Sri Lanka Scimitar-babbler were the nuclear speciesin Riverstan. The leading species were Sri Lanka white-eye and Sri Lanka Yellow-eared Bulbul. Differentbird species used different heights within flocks.Keywords: Mixed-species flock, Nuclear species, Abundance, Foraging flocks

  9. Spatio-temporal dynamics of ocean conditions and forage taxa reveal regional structuring of seabird–prey relationships.

    Science.gov (United States)

    Santora, Jarrod A; Schroeder, Isaac D; Field, John C; Wells, Brian K; Sydeman, William J

    Studies of predator–prey demographic responses and the physical drivers of such relationships are rare, yet essential for predicting future changes in the structure and dynamics of marine ecosystems. Here, we hypothesize that predator–prey relationships vary spatially in association with underlying physical ocean conditions, leading to observable changes in demographic rates, such as reproduction. To test this hypothesis, we quantified spatio-temporal variability in hydrographic conditions, krill, and forage fish to model predator (seabird) demographic responses over 18 years (1990–2007). We used principal component analysis and spatial correlation maps to assess coherence among ocean conditions, krill, and forage fish, and generalized additive models to quantify interannual variability in seabird breeding success relative to prey abundance. The first principal component of four hydrographic measurements yielded an index that partitioned “warm/weak upwelling” and “cool/strong upwelling” years. Partitioning of krill and forage fish time series among shelf and oceanic regions yielded spatially explicit indicators of prey availability. Krill abundance within the oceanic region was remarkably consistent between years, whereas krill over the shelf showed marked interannual fluctuations in relation to ocean conditions. Anchovy abundance varied on the shelf, and was greater in years of strong stratification, weak upwelling and warmer temperatures. Spatio-temporal variability of juvenile forage fish co-varied strongly with each other and with krill, but was weakly correlated with hydrographic conditions. Demographic responses between seabirds and prey availability revealed spatially variable associations indicative of the dynamic nature of “predator–habitat” relationships. Quantification of spatially explicit demographic responses, and their variability through time, demonstrate the possibility of delineating specific critical areas where the

  10. Simulated Optimum Sowing Date for Forage Pearl Millet Cultivars in Multilocation Trials in Brazilian Semi-Arid Region.

    Science.gov (United States)

    Santos, Rafael D; Boote, Kenneth J; Sollenberger, Lynn E; Neves, Andre L A; Pereira, Luiz G R; Scherer, Carolina B; Gonçalves, Lucio C

    2017-01-01

    Forage production is primarily limited by weather conditions under dryland production systems in Brazilian semi-arid regions, therefore sowing at the appropriate time is critical. The objectives of this study were to evaluate the CSM-CERES-Pearl Millet model from the DSSAT software suite for its ability to simulate growth, development, and forage accumulation of pearl millet [ Pennisetum glaucum (L.) R.] at three Brazilian semi-arid locations, and to use the model to study the impact of different sowing dates on pearl millet performance for forage. Four pearl millet cultivars were grown during the 2011 rainy season in field experiments conducted at three Brazilian semi-arid locations, under rainfed conditions. The genetic coefficients of the four pearl millet cultivars were calibrated for the model, and the model performance was evaluated with experimental data. The model was run for 14 sowing dates using long-term historical weather data from three locations, to determine the optimum sowing window. Results showed that performance of the model was satisfactory as indicated by accurate simulation of crop phenology and forage accumulation against measured data. The optimum sowing window varied among locations depending on rainfall patterns, although showing the same trend for cultivars within the site. The best sowing windows were from 15 April to 15 May for the Bom Conselho location; 12 April to 02 May for Nossa Senhora da Gloria; and 17 April to 25 May for Sao Bento do Una. The model can be used as a tool to evaluate the effect of sowing date on forage pearl millet performance in Brazilian semi-arid conditions.

  11. 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.

  12. Migratory geese foraging on grassland:Case study in the region of Flanders (Belgium)

    OpenAIRE

    Van Gils, Bert; De Vliegher, Alex; Huysentruyt, Frank; Casaer, Jim; Devos, Koen

    2012-01-01

    Every winter nearly 100 000 migratory geese visit Northwestern Flanders (Belgium), including several protected species such as the pink-footed goose (Anser brachyrhynchus). The geese mainly forage on agricultural grassland, where they remove all the green parts and leave substantial amounts of droppings. In 2009 several farmers’ concerns about this phenomenon were thoroughly investigated. The main findings revealed that grass production on grazed parcels is reduced by 450 kg DM/ha on average ...

  13. Effects of Plant Density and Nitrogen Fertilizer on Quantity and Quality of Forage Corn in Daregaz Region (Iran

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    N. Saadatzadeh

    2011-01-01

    Full Text Available In order to evaluate the effects of plant density and nitrogen on quantity and quality of forage corn an experiment was conducted in Daregaz region in cropping season 2008 – 2009. The experimental design was a split – plot based on randomized complete block with three replications. The main plots were four levels of nitrogen (0 , 75, 150 and 225 kg/ha and sub plots were three levels of plant density (75000, 100000 and 125000 plant/ha. The results showed that increasing nitrogen levels and plant density, plant height, percentage crude protein and total protein production (ton/ha were increased. By increasing plant density, stem diameter, leaf and ear weight decreased while they increased with increased nitrogen levels. The highest forage yield obtained at nitrogen level 150 kg/ha (46 ton/ha and 100000 plant per hectare (40.27 ton/ha. The highest total protein production (7 ton/ha obtained at nitrogen level of 150 kg/ha and plant density of 125000 plant/ha.

  14. Na and K Levels in forage species from the communal grazing lands during the dry season at some locations in the Northern Region of Ghana

    International Nuclear Information System (INIS)

    Gomda, Y.M.; Osae, E.K.; Akaho, E.H.K.; Fianu, F.K.; Karbo, N.

    1999-04-01

    Forage species were taken, during the dry season, from five districts in the Northern Region of Ghana and analysed for Na and K using the Neutron Activation Analysis (NAA) technique. The Na level varied in plants species as well as location. The level ranged between 0.049 g/kg DM and 1.14 g/kg DM. This was found to be inadequate for the animals and require supplementation during the dry season. Potassium level in the forage species was between 7.8 to 91.3g/kg DM and appeared to be adequate for the grazing animals. (author)

  15. 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.

  16. MACROZOOBENTHOS OF MOUNTAIN RIVERS OF THE TRANSCARPATHIAN REGION AS A FORAGE BASE OF BENTHOPHAGOUS FISHES AND SAPROBITY INDICATOR

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    S. Kruzhylina

    2014-12-01

    Full Text Available Purpose. To study qualitative and qualitative indices of macrozoobenthos as one of main components of the forage base of benthophagous fishes in mountain river reaches of the Transcarpathian region and determination of their saprobity level. Methodology. Thhj,9.e study was carried out in summer period of 2009 in mountain river reaches of the Tisa river catchment. Zoobenthos samples were collected by a Surber sampler (25 × 25 cm on the bottoms of different fractions with different water flow rate (riffle, run, pool. Collection, processing and interpretation of the obtained data was carried out according to generally accepted hydrobiological methods developed for mountain river studies. Saprobity was of the studied rivers was calculated by Pantle-Buck formula. The Zelinka-Marvan saprobity index was used for calculations. Findings. Qualitative and quantitative macrozoobenthos indices have been studied. The number of zoobenthos on the investigated river sections ranged from 416 to 7712 ind./m2 with biomasses from 2.96 to 83.84 g/m2. The major portion of the zoobenthic biomass in the majority of rivers was due to caddis fly larvae composing up to 93% of the total biomass. An important role in the total biomass of the zoobenthos also belonged to mayfly (up to 53% and stonefly (up to 55% larvae and in lower degree amphipods (up to 39%, chironomid larvae (up to 14% and aquatic coleopterans (up to 5%. According to the calculated potential fish productivity, the mountain rivers can be apparently separated into three groups: little productive (4.2–12.7 kg/ha, medium productive (13.2–21.6 kg/ha and high productive (25.3–85.3 kg/ha. Mountain river reaches of the Transcarpathian region were found to belong to pure χ-saprobic, and о- і β-mesosaprobic zones, the saprobity index in which ranged from 0.35 (Rika river to 1.7 (Shipot river. Originality. For further calculation and assessment of brown trout (Salmo trutta and European grayling (Thymallus

  17. 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.

  18. Na and K Levels in forage species from the communal grazing lands during the dry season at some locations in the Northern Region of Ghana

    Energy Technology Data Exchange (ETDEWEB)

    Gomda, Y M; Osae, E K; Akaho, E H.K. [Ghana Atomic Energy Commission, Accra (Ghana); Fianu, F K [University of Ghana, Legon, Accra, (Ghana); Karbo, N [Animal Research Institute, Nyankpala (Ghana)

    1999-09-01

    Forage species were taken, during the dry season, from five districts in the Northern Region of Ghana and analysed for Na and K using the Neutron Activation Analysis (NAA) technique. The Na level varied in plants species as well as location. The level ranged between 0.049 g/kg DM and 1.14 g/kg DM. This was found to be inadequate for the animals and require supplementation during the dry season. Potassium level in the forage species was between 7.8 to 91.3g/kg DM and appeared to be adequate for the grazing animals. (author) Technical report for year ending 1998. 2 tabs.; 18 refs.

  19. Perception of dimethyl sulfide (DMS) by loggerhead sea turtles: a possible mechanism for locating high-productivity oceanic regions for foraging.

    Science.gov (United States)

    Endres, Courtney S; Lohmann, Kenneth J

    2012-10-15

    During their long-distance migrations, sea turtles of several species feed on jellyfish and other invertebrates that are particularly abundant in ocean regions characterized by high productivity. An ability to distinguish productive oceanic regions from other areas, and to concentrate foraging activities in locations where prey density is highest, might therefore be adaptive. The volatile compound dimethyl sulfide (DMS) accumulates in the air above productive ocean areas such as upwelling and frontal zones. In principle, DMS might therefore serve as an indicator of high prey density for turtles. To determine whether turtles perceive DMS, juvenile loggerhead sea turtles (Caretta caretta) were placed into a water-filled arena in which DMS and other odorants could be introduced to the air above the water surface. Turtles exposed to air that had passed over a cup containing 10 nmol l(-1) DMS spent more time at the surface with their noses out of the water than control turtles, which were exposed to air that had passed over a cup containing distilled water. Odors that do not occur in the sea (cinnamon, jasmine and lemon) did not elicit increased surface time, implying that the response to DMS is unlikely to reflect a generalized response to any novel odor. The results demonstrate for the first time that sea turtles can detect DMS, an ability that might enable the identification of favorable foraging areas.

  20. Forage management to improve on-farm feed production, nitrogen fluxes and greenhouse gas emissions from dairy systems in a wet temperate region

    DEFF Research Database (Denmark)

    Doltra, J; Villar, A.; Moros, R

    2018-01-01

    characteristic forage systems according to field management based on grazing, zero-grazing, conserved forages and growth of maize. The semi-dynamic whole farm model FarmAC was used to characterize a model farm representing an average farm in each of the forage systems including field area and use, number of cows...

  1. Agronomic and forage characteristics of Guazuma ulmifolia Lam.

    OpenAIRE

    Manríquez-Mendoza, Leonor Yalid; López-Ortíz, Silvia; Pérez-Hernández, Ponciano; Ortega- Jiménez, Eusebio; López-Tecpoyotl, Zenón Gerardo; Villarruel-Fuentes, Manuel

    2011-01-01

    Native trees are an important source of forage for livestock, particularly in regions having prolonged dry periods. Some tree species have fast growth rates, good nutritional quality, and the ability to produce forage during dry periods when the need for forage is greater. Guazuma ulmifolia Lam. is a tree native to tropical America that has a high forage potential. This species is mentioned in a number of studies assessing the forage potential of trees in a diverse array of environments and v...

  2. Levels of trace elements, methylmercury and polybrominated diphenyl ethers in foraging green turtles in the South China region and their conservation implications.

    Science.gov (United States)

    Ng, Connie Ka Yan; Lam, James Chung Wah; Zhang, Xiao Hua; Gu, He Xiang; Li, Tsung Hsien; Ye, Min Bin; Xia, Zhong Rong; Zhang, Fei Yan; Duan, Jin Xia; Wang, Wen Xiong; Lam, Isaac Kam Sum; Balazs, George H; Lam, Paul K S; Murphy, Margaret B

    2018-03-01

    Sea turtles are globally endangered and face daily anthropogenic threats, including pollution. However, there is a lack of ecotoxicological information on sea turtles, especially in the Asia-Pacific region. This study aims to determine pollutant levels of foraging green turtles (Chelonia mydas) in South China, including Hong Kong, Guangdong and Taiwan, as a basis for their conservation. Scute, liver and muscle tissues of stranded green turtles were analysed for levels of 17 trace elements and methylmercury (MeHg) (n = 86 for scute and n = 14 for liver) and polybrominated diphenyl ethers (PBDEs) (n = 11 for muscle and n = 13 for liver). Ten-fold higher levels of Pb, Ba, V and Tl and 40-fold greater Cd levels were measured in green turtle livers in South China relative to other studies conducted over 10 years ago. Measured PBDE levels were also 27-fold and 50-fold greater than those reported in Australia and Japan. These results warrant further investigation of potential toxicological risks to green turtles in South China and their source rookeries in Malaysia, Micronesia, Indonesia, Marshall Islands, Japan and Taiwan. Research should target monitoring pollutant levels in sea turtles within the West Pacific/Southeast Asia regional management unit spanning East Asia to Southeast Asia to fill in knowledge gaps, in particular in areas such as Thailand, Vietnam, Indonesia, Malaysia and the Philippines where less or no data is available and where foraging grounds of sea turtles have been identified. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Heat Damaged Forages: Effects on Forage Quality

    Science.gov (United States)

    Traditionally, heat damage in forages has been associated with alterations in forage protein quality as a result of Maillard reactions, and most producers and nutritionists are familiar with this concept. However, this is not necessarily the most important negative consequence of spontaneous heating...

  4. Foraging plasticity in seabirds: A non-invasive study of the diet of greater crested terns breeding in the Benguela region

    Science.gov (United States)

    2018-01-01

    Marine predators, such as seabirds, are useful indicators of marine ecosystem functioning. In particular, seabird diet may reflect variability in food-web composition due to natural or human-induced environmental change. Diet monitoring programmes, which sample diet non-invasively, are valuable aids to conservation and management decision-making. We investigated the diet of an increasing population of greater crested terns Thalasseus bergii in the Western Cape, South Africa, during three successive breeding seasons (2013 to 2015), when populations of other seabirds feeding on small pelagic schooling fish in the region were decreasing. Breeding greater crested terns carry prey in their bills, so we used an intensive photo-sampling method to record their diet with little disturbance. We identified 24,607 prey items from at least 47 different families, with 34 new prey species recorded. Fish dominated the diet, constituting 94% of prey by number, followed by cephalopods (3%), crustaceans (2%) and insects (1%). The terns mainly targeted surface-schooling Clupeiformes, with anchovy Engraulis encrasicolus the most abundant prey in all three breeding seasons (65% overall). Prey composition differed significantly between breeding stages and years, with anchovy most abundant at the start of the breeding season, becoming less frequent as the season progressed. The proportion of anchovy in the diet also was influenced by environmental factors; anchovy occurred more frequently with increasing wind speeds and was scarce on foggy days, presumably because terns rely in part on social facilitation to locate anchovy schools. The application of this intensive and non-invasive photo-sampling method revealed an important degree of foraging plasticity for this seabird within a context of locally reduced food availability, suggesting that, unlike species that specialise on a few high-quality prey, opportunistic seabirds may be better able to cope with reductions in the abundance of

  5. Optimally frugal foraging

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    Bénichou, O.; Bhat, U.; Krapivsky, P. L.; Redner, S.

    2018-02-01

    We introduce the frugal foraging model in which a forager performs a discrete-time random walk on a lattice in which each site initially contains S food units. The forager metabolizes one unit of food at each step and starves to death when it last ate S steps in the past. Whenever the forager eats, it consumes all food at its current site and this site remains empty forever (no food replenishment). The crucial property of the forager is that it is frugal and eats only when encountering food within at most k steps of starvation. We compute the average lifetime analytically as a function of the frugality threshold and show that there exists an optimal strategy, namely, an optimal frugality threshold k* that maximizes the forager lifetime.

  6. Integrating Forage, Wildlife, Water, and Fish Projections with Timber Projections at the Regional Level: A Case Study in Southern United States

    Science.gov (United States)

    Linda A. Joyce; Curtis H. Flather; Patricia A. Flebbe; Thomas W. Hoekstra; Stan J. Ursic

    1990-01-01

    The impact of timber management and land-use change on forage production, turkey and deer abundance, red-cockaded woodpecker colonies, water yield, and trout abundance was projected as part of a policy study focusing on the southern United States. The multiresource modeling framework used in this study linked extant timber management and land-area policy models with...

  7. 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

  8. 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.

    Science.gov (United States)

    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 (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.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Neural Mechanisms of Foraging

    OpenAIRE

    Kolling, Nils; Behrens, Timothy EJ; Mars, Rogier B; Rushworth, Matthew FS

    2012-01-01

    Behavioural economic studies, involving limited numbers of choices, have provided key insights into neural decision-making mechanisms. By contrast, animals’ foraging choices arise in the context of sequences of encounters with prey/food. On each encounter the animal chooses to engage or whether the environment is sufficiently rich that searching elsewhere is merited. The cost of foraging is also critical. We demonstrate humans can alternate between two modes of choice, comparative decision-ma...

  11. Projected use of grazed forages in the United States: 2000 to 2050: A technical document supporting the 2000 USDA Forest Service RPA Assessment

    Science.gov (United States)

    Larry W. van Tassell; E. Tom Bartlett; John E. Mitchell

    2001-01-01

    Scenario analysis techniques were used to combine projections from 35 grazed forage experts to estimate future forage demand scenarios and examine factors that are anticipated to impact the use of grazed forages in the South, North, and West Regions of the United States. The amount of land available for forage production is projected to decrease in all regions while...

  12. Adaptive Bacterial Foraging Optimization

    Directory of Open Access Journals (Sweden)

    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.

  13. Forage quantity and quality

    Science.gov (United States)

    Jorgenson, Janet C.; Udevitz, Mark S.; Felix, Nancy A.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.

    2002-01-01

    The Porcupine caribou herd has traditionally used the coastal plain of the Arctic National Wildlife Refuge, Alaska, for calving. Availability of nutritious forage has been hypothesized as one of the reasons the Porcupine caribou herd migrates hundreds of kilometers to reach the coastal plain for calving (Kuropat and Bryant 1980, Russell et al. 1993).Forage quantity and quality and the chronology of snowmelt (which determines availability and phenological stages of forage) have been suggested as important habitat attributes that lead calving caribou to select one area over another (Lent 1980, White and Trudell 1980, Eastland et al. 1989). A major question when considering the impact of petroleum development is whether potential displacement of the caribou from the 1002 Area to alternate calving habitat will limit access to high quantity and quality forage.Our study had the following objectives: 1) quantify snowmelt patterns by area; 2) quantify relationships among phenology, biomass, and nutrient content of principal forage species by vegetation type; and 3) determine if traditional concentrated calving areas differ from adjacent areas with lower calving densities in terms of vegetation characteristics.

  14. Habitat-specific foraging strategies in Australasian gannets

    Directory of Open Access Journals (Sweden)

    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.

  15. Cooperative Bacterial Foraging Optimization

    Directory of Open Access Journals (Sweden)

    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.

  16. New Developments in Forage Varieties

    Science.gov (United States)

    Forage crops harvested for hay or haylage or grazed support dairy, beef, sheep and horse production. Additional livestock production from reduced forage acreage supports the need for forage variety improvement. The Consortium for Alfalfa Improvement is a partnership model of government, private no...

  17. Optimal Foraging in Semantic Memory

    Science.gov (United States)

    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…

  18. Seasonal Food Scarcity Prompts Long-Distance Foraging by a Wild Social Bee.

    Science.gov (United States)

    Pope, Nathaniel S; Jha, Shalene

    2018-01-01

    Foraging is an essential process for mobile animals, and its optimization serves as a foundational theory in ecology and evolution; however, drivers of foraging are rarely investigated across landscapes and seasons. Using a common bumblebee species from the western United States (Bombus vosnesenskii), we ask whether seasonal decreases in food resources prompt changes in foraging behavior and space use. We employ a unique integration of population genetic tools and spatially explicit foraging models to estimate foraging distances and rates of patch visitation for wild bumblebee colonies across three study regions and two seasons. By mapping the locations of 669 wild-caught individual foragers, we find substantial variation in colony-level foraging distances, often exhibiting a 60-fold difference within a study region. Our analysis of visitation rates indicates that foragers display a preference for destination patches with high floral cover and forage significantly farther for these patches, but only in the summer, when landscape-level resources are low. Overall, these results indicate that an increasing proportion of long-distance foraging bouts take place in the summer. Because wild bees are pollinators, their foraging dynamics are of urgent concern, given the potential impacts of global change on their movement and services. The behavioral shift toward long-distance foraging with seasonal declines in food resources suggests a novel, phenologically directed approach to landscape-level pollinator conservation and greater consideration of late-season floral resources in pollinator habitat management.

  19. Avaliação de gramíneas forrageiras na região sul de Minas Gerais Evaluation of forage grasses for the south region of Minas Gerais

    Directory of Open Access Journals (Sweden)

    Milton de Andrade Botrel

    1999-04-01

    Full Text Available Foram conduzidos dois experimentos na região do sul de Minas Gerais para avaliar o potencial de gramíneas forrageiras. No experimento 1 foram avaliadas as seguintes espécies, consideradas de baixa exigência nutricional: Andropogon gayanus, Kunt; Brachiaria brizantha, Stapf; Brachiaria decumbens, Stapf; Brachiaria ruziziensis, Germain Evrard; Brachiaria humidicola (Rendle Schweickt e Melinis minutiflora, Beauv. No experimento 2 foram avaliadas as gramíneas consideradas de média e alta exigência nutricional, a saber: Setaria sphacelata (Schum. Moss; Hemarthria altissima (Poir. Stapf; Chloris gayana, Kunt; Cynodon nlemfuensis, Vanderyst var. nlemfuensis; Hyparrhenia rufa, (Ness Stapf. e as cultivares de Panicum maximum, Jacq.: Tobiatã, Green Panic e Makueni. O delineamento experimental foi de blocos ao acaso com três repetições. Os níveis de calagem e de adubação para estabelecimento e manutenção foram diferenciados para os dois experimentos. Cada espécie foi avaliada nos seguintes aspectos: produção de forragem e teor de proteína bruta no período da seca e das chuvas e cobertura vegetal do solo. As gramíneas do experimento 1 que se destacaram na maioria dos aspectos avaliados foram: B. brizantha, B. decumbens, A. gayanus enquanto que no experimento 2 as espécies que apresentaram maior potencial forrageiro foram: S. sphacelata, P. maximum cv. Tobiatã.experiments were undertaken in the South region of Minas Gerais State, Brazil, to evaluate the yield potential of forage grasses. In experiment 1, the following species, considered as having low nutritional requirements, were evaluated: Andropogon gayanus, Kunt; Brachiaria brizantha, Stapf; Brachiaria decumbens, Stapf; Brachiaria ruziziensis, Germain Evrard; Brachiaria humidicola (Rendle Schweickt and Melinis minutiflora, Beauv. In experiment 2, the species considered as having medium and high nutritional requirements, that is: Setaria sphacelata (Schum.; Hemarthria altissima

  20. Effect of forage quality in faeces from different ruminant species fed high and low quality forage

    DEFF Research Database (Denmark)

    Jalali, A R; Nørgaard, P; Nielsen, M O

    2010-01-01

    Effect of forage quality in faeces from different ruminant species fed high and low quality forage......Effect of forage quality in faeces from different ruminant species fed high and low quality forage...

  1. forage systems mixed with forage legumes grazed by lactating cows

    Directory of Open Access Journals (Sweden)

    Clair Jorge Olivo

    2017-02-01

    Full Text Available Current research evaluates productivity, stocking and nutritional rates of three forage systems with Elephant Grass (EG + Italian Ryegrass (IR + Spontaneous Growth Species (SGS, without forage legumes; EG + IR + SGS + Forage Peanut (FP, mixed with FP; and EG + IR + SGS + Red Clover (RC, mixed with RC, in rotational grazing method by lactating cows. IR developed between rows of EG. FP was maintained, whilst RC was sow to respective forage systems. The experimental design was completely randomized, with three treatments and two replication, subdivided into parcels over time. Mean rate for forage yield and average stocking rate were 10.6, 11.6 and 14.4 t ha-1; 3.0, 2.8 and 3.1 animal unit ha-1 day-1, for the respective systems. Levels of crude protein and total digestible nutrients were 17.8, 18.7 and 17.5%; 66.5, 66.8 and 64.8%, for the respective forage systems. The presence of RC results in better and higher forage yield in the mixture, whilst FP results in greater control of SGS. The inclusion of forage legumes in pasture systems provides better nutritional rates.

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

    Directory of Open Access Journals (Sweden)

    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

  3. Forage evaluation by analysis after

    African Journals Online (AJOL)

    by forages, can be estimated by amino acid analysis of the products of fermentation in vitro. Typical results of such analyses are presented in Table 1. These results indicate that after fermentation the amino acid balance of forages is not optimal for either milk or meat production, with histidine usually being the first limiting.

  4. 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.

    Directory of Open Access Journals (Sweden)

    Angela R Lieverse

    Full Text Available 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.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Biomass production and forage quality of head-smut disease ...

    African Journals Online (AJOL)

    Napier grass, commonly known as “elephant grass”, is a major feed used for dairy production by smallholder farmers in eastern and central Africa. However, the productivity of the grass in the region is threatened by stunt and head-smut diseases. The objective of this study was to determine biomass yield and forage quality ...

  11. Attraction of Vespula germanica (Hymenoptera: Vespidae) foragers by conspecific heads.

    Science.gov (United States)

    d'Adamo, P; Corley, J C; Lozada, M

    2001-08-01

    The socialwasp Vespula germanica (F.) is a serious pest in many regions it has invaded. Control programs to reduce its populations are commonly based on the use of poison baits. These baits also attract nonpestiferous invertebrates and vertebrates. In this work we studied the attraction of V. germanica foragers by conspecific worker squashes, comparing the effect of head and abdomen squashes in wasps behavior. We found that head squashes attract V. germanica foragers, elicit landing and transportation to nests. Furthermore, the addition of squashed heads to a protein bait increased attraction. This could be an alternative to improve baiting programs.

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

    Directory of Open Access Journals (Sweden)

    Caroline L Poli

    Full Text Available 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

  13. 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

  14. Comparative Effect of Sole Forage and Mixed Concentrate-Forage ...

    African Journals Online (AJOL)

    There was no statistical (P>0.05) difference in average intake of forage between the two treatment groups. Economically, Treatment 1 proves to be better for the enhancement of body weight in growing rabbits than Treatment 2. Key words: Weaner rabbits,Poultry grower mesh, Tridax procumbens, Feed intake,Body weight ...

  15. 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

  16. 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...

  17. Triticale for dairy forage systems

    Science.gov (United States)

    Triticale forages have become increasingly important components of dairy-cropping systems. In part, this trend has occurred in response to environmental pressures, specifically a desire to capture N and other nutrients from land-applied manure, and/or to improve stewardship of the land by providing ...

  18. 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. ...

  19. Risso's dolphins plan foraging dives.

    Science.gov (United States)

    Arranz, Patricia; Benoit-Bird, Kelly J; Southall, Brandon L; Calambokidis, John; Friedlaender, Ari S; Tyack, Peter L

    2018-02-28

    Humans remember the past and use that information to plan future actions. Lab experiments that test memory for the location of food show that animals have a similar capability to act in anticipation of future needs, but less work has been done on animals foraging in the wild. We hypothesized that planning abilities are critical and common in breath-hold divers who adjust each dive to forage on prey varying in quality, location and predictability within constraints of limited oxygen availability. We equipped Risso's dolphins with sound-and-motion recording tags to reveal where they focus their attention through their externally observable echolocation and how they fine tune search strategies in response to expected and observed prey distribution. The information from the dolphins was integrated with synoptic prey data obtained from echosounders on an underwater vehicle. At the start of the dives, whales adjusted their echolocation inspection ranges in ways that suggest planning to forage at a particular depth. Once entering a productive prey layer, dolphins reduced their search range comparable to the scale of patches within the layer, suggesting that they were using echolocation to select prey within the patch. On ascent, their search range increased, indicating that they decided to stop foraging within that layer and started searching for prey in shallower layers. Information about prey, learned throughout the dive, was used to plan foraging in the next dive. Our results demonstrate that planning for future dives is modulated by spatial memory derived from multi-modal prey sampling (echoic, visual and capture) during earlier dives. © 2018. Published by The Company of Biologists Ltd.

  20. 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

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

    OpenAIRE

    Grajales-Conesa,Julieta; Meléndez Ramírez,Virginia; Cruz-López,Leopoldo; Sánchez Guillén,Daniel

    2012-01-01

    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 behavi...

  2. Maize stubble as foraging habitat for wintering geese and swans in northern Europe

    DEFF Research Database (Denmark)

    Clausen, Kevin Kuhlmann; Madsen, Jesper; Nolet, Bart, A.

    2018-01-01

    Agricultural crops have become increasingly important foraging habitats to geese and swans in northern Europe, and a recent climate-driven expansion in the area of maize fields has led to a rapid increase in the exploitation of this habitat. However, due to the novelty of maize foraging in this r......Agricultural crops have become increasingly important foraging habitats to geese and swans in northern Europe, and a recent climate-driven expansion in the area of maize fields has led to a rapid increase in the exploitation of this habitat. However, due to the novelty of maize foraging...... in this region, little is known about the abundance and energetic value of this resource to foraging birds. In this study we quantify food availability, intake rates and energetic profitability of the maize stubble habitat, and describe the value of this increasingly cultivated crop to wintering geese and swans...... of geese and swans wintering in northern Europe....

  3. 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

  4. Monitoring Forage Production of California Rangeland Using Remote Sensing Observations

    Science.gov (United States)

    Liu, H.; Jin, Y.; Dahlgren, R. A.; O'Geen, A. T.; Roche, L. M.; Smith, A. M.; Flavell, D.

    2016-12-01

    Pastures and rangeland cover more than 10 million hectares in California's coastal and inland foothill regions, providing feeds to livestock and important ecosystem services. Forage production in California has a large year-to-year variation due to large inter-annual and seasonal variabilities in precipitation and temperature. It also varies spatially due to the variability in climate and soils. Our goal is to develop a robust and cost-effective tool to map the near-real-time and historical forage productivity in California using remote sensing observations from Landsat and MODIS satellites. We used a Monteith's eco-physiological plant growth theory: the aboveground net primary production (ANPP) is determined by (i) the absorbed photosynthetically active radiation (APAR) and the (ii) light use efficiency (LUE): ANPP = APAR * LUEmax * f(T) * f(SM), where LUEmax is the maximum LUE, and f(T) and f(SM) are the temperature and soil moisture constrains on LUE. APAR was estimated with Landsat and MODIS vegetation index (VI), and LUE was calibrated with a statewide point dataset of peak forage production measurements at 75 annual rangeland sites. A non-linear optimization was performed to derive maximum LUE and the parameters for temperature and soil moisture regulation on LUE by minimizing the differences between the estimated and measured ANPP. Our results showed the satellite-derived annual forage production estimates correlated well withcontemporaneous in-situ forage measurements and captured both the spatial and temporal productivity patterns of forage productivity well. This remote sensing algorithm can be further improved as new field measurements become available. This tool will have a great importance in maintaining a sustainable range industry by providing key knowledge for ranchers and the stakeholders to make managerial decisions.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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. © 2016 by the Ecological Society of America.

  10. Extreme precipitation variability, forage quality and large herbivore diet selection in arid environments

    Science.gov (United States)

    Cain, James W.; Gedir, Jay V.; Marshal, Jason P.; Krausman, Paul R.; Allen, Jamison D.; Duff, Glenn C.; Jansen, Brian; Morgart, John R.

    2017-01-01

    Nutritional ecology forms the interface between environmental variability and large herbivore behaviour, life history characteristics, and population dynamics. Forage conditions in arid and semi-arid regions are driven by unpredictable spatial and temporal patterns in rainfall. Diet selection by herbivores should be directed towards overcoming the most pressing nutritional limitation (i.e. energy, protein [nitrogen, N], moisture) within the constraints imposed by temporal and spatial variability in forage conditions. We investigated the influence of precipitation-induced shifts in forage nutritional quality and subsequent large herbivore responses across widely varying precipitation conditions in an arid environment. Specifically, we assessed seasonal changes in diet breadth and forage selection of adult female desert bighorn sheep Ovis canadensis mexicana in relation to potential nutritional limitations in forage N, moisture and energy content (as proxied by dry matter digestibility, DMD). Succulents were consistently high in moisture but low in N and grasses were low in N and moisture until the wet period. Nitrogen and moisture content of shrubs and forbs varied among seasons and climatic periods, whereas trees had consistently high N and moderate moisture levels. Shrubs, trees and succulents composed most of the seasonal sheep diets but had little variation in DMD. Across all seasons during drought and during summer with average precipitation, forages selected by sheep were higher in N and moisture than that of available forage. Differences in DMD between sheep diets and available forage were minor. Diet breadth was lowest during drought and increased with precipitation, reflecting a reliance on few key forage species during drought. Overall, forage selection was more strongly associated with N and moisture content than energy content. Our study demonstrates that unlike north-temperate ungulates which are generally reported to be energy-limited, N and moisture

  11. 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

    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...... opportunities. We cut and cleared small swaths of dense bamboo growth for an unrelated study. Multiple insectivorous species were recruited to the cleared areas, foraging extensively in the disturbed earth, often within 1 m of us. These species included Tarsiger chrysaeus, Tarsiger indicus, Cettia brunnifrons...

  12. Visual Foraging With Fingers and Eye Gaze

    Directory of Open Access Journals (Sweden)

    Ómar I. Jóhannesson

    2016-03-01

    Full Text Available 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.

  13. Boa constrictor (Boa constrictor): foraging behavior

    Science.gov (United States)

    Sorrell, G.G.; Boback, M.S.; Reed, R.N.; Green, S.; Montgomery, Chad E.; DeSouza, L.S.; Chiaraviglio, M.

    2011-01-01

    Boa constrictor is often referred to as a sit-and-wait or ambush forager that chooses locations to maximize the likelihood of prey encounters (Greene 1983. In Janzen [ed.], Costa Rica Natural History, pp. 380-382. Univ. Chicago Press, Illinois). However, as more is learned about the natural history of snakes in general, the dichotomy between active versus ambush foraging is becoming blurred. Herein, we describe an instance of diurnal active foraging by a B. constrictor, illustrating that this species exhibits a range of foraging behaviors.

  14. 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,...

  15. 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,...

  16. Social Learning in Vespula Germanica Wasps: Do They Use Collective Foraging Strategies?

    OpenAIRE

    Lozada, Mariana; D? Adamo, Paola; Buteler, Micaela; Kuperman, Marcelo N.

    2016-01-01

    Vespula germanica is a social wasp that has become established outside its native range in many regions of the world, becoming a major pest in the invaded areas. In the present work we analyze social communication processes used by V. germanica when exploiting un-depleted food sources. For this purpose, we investigated the arrival pattern of wasps at a protein bait and evaluated whether a forager recruited conspecifics in three different situations: foragers were able to return to the nest (f...

  17. A global comparison of the nutritive values of forage plants grown in contrasting environments.

    Science.gov (United States)

    Lee, Mark A

    2018-03-17

    Forage plants are valuable because they maintain wild and domesticated herbivores, and sustain the delivery of meat, milk and other commodities. Forage plants contain different quantities of fibre, lignin, minerals and protein, and vary in the proportion of their tissue that can be digested by herbivores. These nutritive components are important determinants of consumer growth rates, reproductive success and behaviour. A dataset was compiled to quantify variation in forage plant nutritive values within- and between-plant species, and to assess variation between plant functional groups and bioclimatic zones. 1255 geo-located records containing 3774 measurements of nutritive values for 136 forage plant species grown in 30 countries were obtained from published articles. Spatial variability in forage nutritive values indicated that climate modified plant nutritive values. Forage plants grown in arid and equatorial regions generally contained less digestible material than those grown in temperate and tundra regions; containing more fibre and lignin, and less protein. These patterns may reveal why herbivore body sizes, digestion and migration strategies are different in warmer and drier regions. This dataset also revealed the capacity for variation in the nutrition provided by forage plants, which may drive consumer species coexistence. The proportion of the plant tissue that was digestible ranged between species from 2 to 91%. The amount of fibre contained within plant material ranged by 23-90%, protein by 2-36%, lignin by 1-21% and minerals by 2-22%. On average, grasses and tree foliage contained the most fibre, whilst herbaceous legumes contained the most protein and tree foliage contained the most lignin. However, there were individual species within each functional group that were highly nutritious. This dataset may be used to identify forage plant species or mixtures of species from different functional groups with useful nutritional traits which can be cultivated

  18. 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

  19. 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, paral...

  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. 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…

  2. BEE FORAGE MAPPING BASED ON MULTISPECTRAL IMAGES LANDSAT

    Directory of Open Access Journals (Sweden)

    A. Moskalenko

    2016-10-01

    Full Text Available Possibilities of bee forage identification and mapping based on multispectral images have been shown in the research. Spectral brightness of bee forage has been determined with the use of satellite images. The effectiveness of some methods of image classification for mapping of bee forage is shown. Keywords: bee forage, mapping, multispectral images, image classification.

  3. 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. 

  4. Avian predator buffers against variability in marine habitats with flexible foraging behavior

    Science.gov (United States)

    Schoen, Sarah K.; Piatt, John F.; Arimitsu, Mayumi L.; Heflin, Brielle; Madison, Erica N.; Drew, Gary S.; Renner, Martin; Rojek, Nora A.; Douglas, David C.; DeGange, Anthony R.

    2018-01-01

    How well seabirds compensate for variability in prey abundance and composition near their breeding colonies influences their distribution and reproductive success. We used tufted puffins (Fratercula cirrhata) as forage fish samplers to study marine food webs from the western Aleutian Islands (53°N, 173°E) to Kodiak Island (57°N, 153°W), Alaska, during August 2012–2014. Around each colony we obtained data on: environmental characteristics (sea surface temperature and salinity, seafloor depth and slope, tidal range, and chlorophyll-a), relative forage fish biomass (hydroacoustic backscatter), and seabird community composition and density at-sea. On colonies, we collected puffin chick-meals to characterize forage communities and determine meal energy density, and measured chicks to obtain a body condition index. There were distinct environmental gradients from west to east, and environmental variables differed by ecoregions: the (1) Western-Central Aleutians, (2) Eastern Aleutians, and, (3) Alaska Peninsula. Forage fish biomass, species richness, and community composition all differed markedly between ecoregions. Forage biomass was strongly correlated with environmental gradients, and environmental gradients and forage biomass accounted for ~ 50% of the variability in at-sea density of tufted puffins and all seabird taxa combined. Despite the local and regional variability in marine environments and forage, the mean biomass of prey delivered to puffin chicks did not differ significantly between ecoregions, nor did chick condition or puffin density at-sea. We conclude that puffins can adjust their foraging behavior to produce healthy chicks across a wide range of environmental conditions. This extraordinary flexibility enables their overall success and wide distribution across the North Pacific Ocean.

  5. 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.

  6. CHEMICAL COMPOSITION OF CAATINGA POTENTIAL FORAGES SPECIES

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    Dynara Layza de Souza da Silva

    2015-12-01

    Full Text Available Chemical composition of some potential forages species, natives from Caatinga region, were evaluated. Samples of Macroptilium heterophyllum, Stylosanthes humilis, Rhynchosia mínima, Desmodium tortuosum Sw. Dc, Merremia aegyptia, Mimosa tenuiflora Wild, Bauhinia cheilantha and as well Macroptilium lathyroides, Caesalpinia pyramidalis and Mimosa tenuiflora hays were collected in Rio Grande do Norte Stated, during 2011 rainy season. The analyses: dry matter (DM, crude protein (CP mineral matter (MM ether extract  (EE neutral detergent fiber (NDF, acid detergent fiber (ADF, lignin (LIG, insoluble neutral detergent nitrogen, (INDN insoluble acid detergent nitrogen, (ADIN, total phenol (TF and total tannin (TT were done at Embrapa Caprinos e Ovinos in Ceará State. Plants analyzed, as expected, for tropical species, exhibited high level of cell wall constituents, high lignifications rate and revealed substantial presence of anti nutritional compounds. However, regardless of this data, the main problem, for grazing animals, is due to its xerophytes characteristics. Most of the shrubs and trees are deciduous, losing its leaves during the dry season. In addition, herbaceous presents a very rapid lifetime cycle, germinating and senescing during the brief wet season.

  7. Group foraging increases foraging efficiency in a piscivorous diver, the African penguin

    Science.gov (United States)

    McGeorge, Cuan; Ginsberg, Samuel; Pichegru, Lorien; Pistorius, Pierre A.

    2017-01-01

    Marine piscivores have evolved a variety of morphological and behavioural adaptations, including group foraging, to optimize foraging efficiency when targeting shoaling fish. For penguins that are known to associate at sea and feed on these prey resources, there is nonetheless a lack of empirical evidence to support improved foraging efficiency when foraging with conspecifics. We examined the hunting strategies and foraging performance of breeding African penguins equipped with animal-borne video recorders. Individuals pursued both solitary as well as schooling pelagic fish, and demonstrated independent as well as group foraging behaviour. The most profitable foraging involved herding of fish schools upwards during the ascent phase of a dive where most catches constituted depolarized fish. Catch-per-unit-effort was significantly improved when targeting fish schools as opposed to single fish, especially when foraging in groups. In contrast to more generalist penguin species, African penguins appear to have evolved specialist hunting strategies closely linked to their primary reliance on schooling pelagic fish. The specialist nature of the observed hunting strategies further limits the survival potential of this species if Allee effects reduce group size-related foraging efficiency. This is likely to be exacerbated by diminishing fish stocks due to resource competition and environmental change. PMID:28989785

  8. Forage: a sensitive indicator of airborne radioactivity

    International Nuclear Information System (INIS)

    Jackson, W.M.; Noakes, J.E.; Spaulding, J.D.

    1981-01-01

    This paper presents the results of using Ge(Li) γ-ray spectroscopy to measure radioactivity concentration of forage in the vicinity of the Joseph M. Farley Nuclear Plant, Houston County, AL., over a 31/2 yr period. The report period includes 2 yr of pre-operational and 11/2 yr of operational sampling. Although the objective of forage sampling was the measurement of manmade airborne fallout radioactivity, several natural radioisotopes were also found to be present. A summary of natural radioactivity data for all samples measured during the period from August 1975 to December 1978 is given. Approximately 10 days after each of four Chinese atmospheric nuclear tests conducted during the sampling period fresh fission product fallout was measured on the forage. The information from these nuclear tests shows forage sampling to be a convenient and sensitive monitoring tool for airborne fallout radioactivity. (author)

  9. 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

  10. African Journal of Range and Forage Science

    African Journals Online (AJOL)

    The African Journal of Range & Forage Science is the leading rangeland and pastoral journal in Africa. The Journal is dedicated to publishing quality original material that advances rangeland ecology and pasture management in Africa. Read more abou the journal here.

  11. Annual forage cropping-systems for midwestern ruminant livestock production

    OpenAIRE

    McMillan, John Ernest

    2016-01-01

    Annual forage cropping systems are a vital aspect of livestock forage production. One area where this production system can be enhanced is the integration of novel annual forages into conventional cropping systems. Two separate projects were conducted to investigate alternative forage options in annual forage production. In the first discussed research trial, two sets of crops were sown following soft red winter wheat (Triticum aestivum L.) grain harvest, at two nitrogen application rates 56 ...

  12. Evidence of trapline foraging in honeybees.

    Science.gov (United States)

    Buatois, Alexis; Lihoreau, Mathieu

    2016-08-15

    Central-place foragers exploiting floral resources often use multi-destination routes (traplines) to maximise their foraging efficiency. Recent studies on bumblebees have showed how solitary foragers can learn traplines, minimising travel costs between multiple replenishing feeding locations. Here we demonstrate a similar routing strategy in the honeybee (Apis mellifera), a major pollinator known to recruit nestmates to discovered food resources. Individual honeybees trained to collect sucrose solution from four artificial flowers arranged within 10 m of the hive location developed repeatable visitation sequences both in the laboratory and in the field. A 10-fold increase of between-flower distances considerably intensified this routing behaviour, with bees establishing more stable and more efficient routes at larger spatial scales. In these advanced social insects, trapline foraging may complement cooperative foraging for exploiting food resources near the hive (where dance recruitment is not used) or when resources are not large enough to sustain multiple foragers at once. © 2016. Published by The Company of Biologists Ltd.

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

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    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. Relationship between chemical composition of native forage and nutrient digestibility by Tibetan sheep on the Qinghai-Tibetan Plateau.

    Science.gov (United States)

    Yang, Chuntao; Gao, Peng; Hou, Fujiang; Yan, Tianhai; Chang, Shenghua; Chen, Xianjiang; Wang, Zhaofeng

    2018-04-02

    To better utilize native pasture at the high altitude region, three-consecutive-year feeding experiments and a total of seven metabolism trials were conducted to evaluate the impact of three forage stages of maturity on the chemical composition, nutrient digestibility, and energy metabolism of native forage in Tibetan sheep on the Qinghai-Tibetan Plateau (QTP). Forages were harvested from June to July, August to October, and November to December of 2011 to 2013, corresponding to the vegetative, bloom, and senescent stages of the annual forages. Twenty male Tibetan sheep were selected for each study and fed native forage ad libitum. The digestibility of DM, OM, CP, NDF, ADF, DE, DE/GE, and ME/GE were greatest (P digestibility and energy parameters correlated positively (linear, 0.422 to 0.778; quadratic, 0.568 to 0.815; P digestibility. Contrary to previous studies, in this study, ADF content had a greater linear relationship (0.766 vs. 0.563 to 0.732) with OM digestibility than the other parameters of nutrient digestibility. The quadratic relationship between forage CP content and CP digestibility indicates that when forage CP content exceeds the peak point (9.7% DM in the present study), increasing forage CP content could decrease CP digestibility when Tibetan sheep were offered native forage alone on the QTP. Additionally, using the forage CP, EE, NDF, and ADF content to predict DMI (g/kg BW·d) yielded the best fit equation for Tibetan sheep living in the northeast portion of the QTP.

  15. Individual lifetime pollen and nectar foraging preferences in bumble bees

    Science.gov (United States)

    Hagbery, Jessica; Nieh, James C.

    2012-10-01

    Foraging specialization plays an important role in the ability of social insects to efficiently allocate labor. However, relatively little is known about the degree to which individual bumble bees specialize on collecting nectar or pollen, when such preferences manifest, and if individuals can alter their foraging preferences in response to changes in the colony workforce. Using Bombus impatiens, we monitored all foraging visits made by every bee in multiple colonies and showed that individual foragers exhibit consistent lifetime foraging preferences. Based upon the distribution of foraging preferences, we defined three forager types (pollen specialists, nectar specialists, and generalists). In unmanipulated colonies, 16-36 % of individuals specialized (≥90 % of visits) on nectar or pollen only. On its first day of foraging, an individual's foraging choices (nectar only, pollen only, or nectar and pollen) significantly predicted its lifetime foraging preferences. Foragers that only collected pollen on their first day of foraging made 1.61- to 1.67-fold more lifetime pollen foraging visits (as a proportion of total trips) than foragers that only collected nectar on their first foraging day. Foragers were significantly larger than bees that stayed only in the nest. We also determined the effect of removing pollen specialists at early (brood present) or later (brood absent) stages in colony life. These results suggest that generalists can alter their foraging preferences in response to the loss of a small subset of foragers. Thus, bumble bees exhibit individual lifetime foraging preferences that are established early in life, but generalists may be able to adapt to colony needs.

  16. A decision-making support system to select forages according to environmental conditions in Colombia

    Directory of Open Access Journals (Sweden)

    Blanca Aurora Arce Barboza

    2013-07-01

    Full Text Available Low food supply is a major problem affecting a large percentage of the livestock population in Colombia and is largely associated to inappropriate choice of forage species; and thus not well adapted to the environmental conditions of a specific region. To mitigate this problem, without incurring increasing costs associated to changing environmental conditions, it is possible to match the adaptive capacity of species to the environment in which they grow. A decision support system was developed to select suitable forage species for a given environment. The system is based on the use of existing information about requirements of the species rather than specific experimentation. From the information gathered, a database was generated and implemented on ASP.NET in C # and SQL Server database. This system allows users to search and select pastures and forage species for specific soil and climatic conditions of a particular farm or region, through a user-friendly web platform.

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

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    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.

  18. 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

  19. 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

    2017-03-01

    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. 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. Significant differences were found in the non-fiber carbohydrate (NFC) content among the forage species and the regions (pruminal fermentation of LPF between the two regions and interactions between regions and forage species were also significant (pruminal 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 Jeolla. Analysis of gas production profiles showed the rate of fermentation differed among forage species (p<0.05). The results of the present study showed that the nutritional values of some LPF (i.e., corn silage and Italian ryegrass) are comparable to those of imported forages widely used in Korea. This study also indicated that the nutritional value of LPF differs by origin, as well as by forage species. Detailed analyses of nutrient

  20. 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.

  1. Cognitive plasticity in foraging Vespula germanica wasps.

    Science.gov (United States)

    D'Adamo, Paola; Lozada, Mariana

    2011-01-01

    Vespula germanica (F.) (Hymenoptera: Vespidae) is a highly invasive social wasp that exhibits a rich behavioral repertoire in which learning and memory play a fundamental role in foraging. The learning abilities of these wasps were analyzed while relocating a food source and whether V. germanica foragers are capable of discriminating between different orientation patterns and generalizing their choice to a new pattern. Foraging wasps were trained to associate two different stripe orientation patterns with their respective food locations. Their response to a novel configuration that maintained the orientation of one of the learned patterns but differed in other aspects (e.g. width of stripes) was then evaluated. The results support the hypothesis that V. germanica wasps are able to associate a particular oriented pattern with the location of a feeder and to generalize their choice to a new pattern, which differed in quality, but presented the same orientation.

  2. Forage production in mixed grazing systems of elephant grass with arrowleaf clover or forage peanut

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    Daiane Cristine Seibt

    Full Text Available ABSTRACT Most dairy production systems are pasture-based, usually consisting of sole grass species. This system facilitates pasture management, but results in high production costs, mainly because of nitrogen fertilizers. An alternative to making forage systems more sustainable is to introduce legumes into the pasture. Mixed pastures allow better forage distribution over time and reduce fertilization costs. Thus, the objective of this study was to evaluate, throughout the year, three forage systems (FS: FS1 (control - elephant grass (EG, ryegrass (RG, and spontaneous species (SS; FS2 - EG + RG + SS + arrowleaf clover; and FS3 - EG + RG + SS + forage peanut. Elephant grass was planted in rows spaced 4 m apart. Ryegrass was sown between the EG lines, in the winter. Arrowleaf clover was sown according to the respective treatments and forage peanut was preserved. Evaluation was carried out using Holstein cows. The experiment was arranged in a completely randomized design, with three treatments (FS, and three repetitions (paddocks with repeated measurements (grazing cycles. Forage mass achieved 3.46, 3.80, and 3.91 t ha-1 for the treatments FS1, FS2 and FS3, respectively. The forage systems intercropped with legumes produced the best results.

  3. Dental evidence for wild tuber processing among Titicaca Basin foragers 7000 ybp.

    Science.gov (United States)

    Watson, James T; Haas, Randall

    2017-09-01

    The objective of this work is to characterize dental wear in a skeletal sample dating to the Middle/Late Archaic period transition (8,000-6,700 cal. B.P.) from the Lake Titicaca Basin, Peru to better define subsistence behaviors of foragers prior to incipient sedentism and food production. The dental sample consists of 251 teeth from 11 individuals recovered from the site of Soro Mik'aya Patjxa (SMP), the earliest securely dated burial assemblage in the Lake Titicaca Basin and the only burial assemblage in the region from an unequivocal forager context. Occlusal surface wear was quantified according to Smith (1984) and Scott (1979a) to characterize diversity within the site and to facilitate comparison with other foraging groups worldwide. General linear modeling was used to assess observation error and principal axis analysis was used to compare molar wear rates and angles. Teeth were also examined for caries and specialized wear. Occlusal surface attrition is generally heavy across the dental arcade and tends to be flat among posterior teeth. Only one carious lesion was observed. Five of the 11 individuals exhibit lingual surface attrition of the maxillary anterior teeth (LSAMAT). Tooth wear rates, molar wear plane, and caries rates are consistent with terrestrial foraging and a diverse diet. The presence of LSAMAT indicates tuber processing. The results therefore contribute critical new data toward our understanding of forager diet in the Altiplano prior to plant and animal domestication in the south-central Andes. © 2017 Wiley Periodicals, Inc.

  4. 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.

  5. 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.

  6. 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.

  7. Hooded seal Cystophora cristata foraging areas in the Northeast Atlantic Ocean-Investigated using three complementary methods.

    Directory of Open Access Journals (Sweden)

    Jade Vacquie-Garcia

    Full Text Available Identifying environmental characteristics that define the ecological niche of a species is essential to understanding how changes in physical conditions might affect its distribution and other aspects of its ecology. The present study used satellite relay data loggers (SRDLs to study habitat use by Northeast Atlantic hooded seals (N = 20; 9 adult females, 3 adult males, and 8 juveniles. Three different methods were used in combination to achieve maximum insight regarding key foraging areas for hooded seals in this region, which have decline by 85% in recent decades: 1 first passage time (FPT; 2 vertical transit rate and; 3 change in dive drift rate. Generalized additive mixed models (GAMM were applied to each method to determine whether specific habitat characteristics were associated with foraging. Separate models were run for the post-molting and the post-breeding seasons; sex and age classes were included in the GAMMs. All three methods highlighted a few common geographic areas as being important foraging zones; however, there were also some different areas identified by the different methods, which highlights the importance of using multiple indexes when analyzing tracking and diving data to study foraging behavior. Foraging occurred most commonly in relatively shallow areas with high Sea Surface Temperatures (SST, corresponding to continental shelf areas with Atlantic Water masses. All age and sex classes overlapped spatially to some extent, but the different age and sex groups showed differences in the bathymetry of their foraging areas as well as in their vertical use of the water column. When foraging, pups dove in the upper part of the water column in relatively deep areas. Adult females foraged relatively shallowly in deep water areas too, though in shallower areas than pups. Adult males foraged close to the bottom in shallower areas.

  8. 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.

  9. Information Foraging Theory: A Framework for Intelligence Analysis

    Science.gov (United States)

    2014-11-01

    oceanographic information, human intelligence (HUMINT), open-source intelligence ( OSINT ), and information provided by other governmental departments [1][5...Human Intelligence IFT Information Foraging Theory LSA Latent Semantic Similarity MVT Marginal Value Theorem OFT Optimal Foraging Theory OSINT

  10. 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....

  11. Social foraging by waterbirds in shallow coastal lagoons in Ghana

    NARCIS (Netherlands)

    Battley, PF; Poot, M; Wiersma, P; Gordon, C; Ntiamoa-Baidu, Y; Piersma, T; Battley, Phil F.

    Social foraging in waterbirds in Ghanaian coastal lagoons was studied during October and November 1994. Two types of foraging were social: directionally synchronized flocks (often involving distinctive feeding methods used in unison) and dense pecking aggregations. Social flocks were typically

  12. 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.

  13. Puffins reveal contrasting relationships between forage fish and ocean climate in the North Pacific

    Science.gov (United States)

    Sydeman, William J.; Piatt, John F.; Thompson, Sarah Ann; Garcia-Reyes, Marisol; Hatch, Scott A.; Arimitsu, Mayumi L.; Slater, Leslie; Williams, Jeffrey C.; Rojek, Nora A.; Zador, Stephani G.; Renner, Heather M.

    2017-01-01

    Long-term studies of predator food habits (i.e., ‘predator-based sampling’) are useful for identifying patterns of spatial and temporal variability of forage nekton in marine ecosystems. We investigated temporal changes in forage fish availability and relationships to ocean climate by analyzing diet composition of three puffin species (horned puffin Fratercula corniculata, tufted puffin Fratercula cirrhata, and rhinoceros auklet Cerorhinca monocerata) from five sites in the North Pacific from 1978–2012. Dominant forage species included squids and hexagrammids in the western Aleutians, gadids and Pacific sand lance (Ammodytes personatus) in the eastern Aleutians and western Gulf of Alaska (GoA), and sand lance and capelin (Mallotus villosus) in the northern and eastern GoA. Interannual fluctuations in forage availability dominated variability in the western Aleutians, whereas lower-frequency shifts in forage fish availability dominated elsewhere. We produced regional multivariate indicators of sand lance, capelin, and age-0 gadid availability by combining data across species and sites using Principal Component Analysis, and related these indices to environmental factors including sea level pressure (SPL), winds, and sea surface temperature (SST). There was coherence in the availability of sand lance and capelin across the study area. Sand lance availability increased linearly with environmental conditions leading to warmer ocean temperatures, whereas capelin availability increased in a non-linear manner when environmental changes led to lower ocean temperatures. Long-term studies of puffin diet composition appear to be a promising tool for understanding the availability of these difficult-to-survey forage nekton in remote regions of the North Pacific.

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

    Directory of Open Access Journals (Sweden)

    Massimiliano Drago

    Full Text Available 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 (δ(13C and δ(15N 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.

  15. 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...

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

    African Journals Online (AJOL)

    Novin

    2012-07-17

    Jul 17, 2012 ... and chemical composition of forage species was estimated. MATERIALS AND METHODS ... head per day at 8.00 a.m. and 6.00 p.m. Forage samples (2 g DM with 2 mm screen ) were weighed into nylon bags ..... methods to study the kinetics of degradation of forage species, instead of the in situ technique, ...

  17. 7 CFR 407.13 - Group risk plan for forage.

    Science.gov (United States)

    2010-01-01

    ... acres of hay in the county, as specified in the actuarial documents. The actuarial documents will... a period for forage regrowth. 2. Crop Insured The insured crop will be the forage types shown on the... the Group Risk Plan Common Policy, acreage seeded to forage after July 1 of the previous crop year...

  18. 7 CFR 457.117 - Forage production crop insurance provisions.

    Science.gov (United States)

    2010-01-01

    ... INSURANCE CORPORATION, DEPARTMENT OF AGRICULTURE COMMON CROP INSURANCE REGULATIONS § 457.117 Forage..., or a mixture thereof, or other species as shown in the Actuarial Documents. Harvest—Removal of forage... different price elections by type, in which case you may select one price election for each forage type...

  19. 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...

  20. Adaptive foraging and flexible food web topology

    Czech Academy of Sciences Publication Activity Database

    Křivan, Vlastimil; Schmitz, O.

    2003-01-01

    Roč. 5, - (2003), s. 623-652 ISSN 1522-0613 R&D Projects: GA ČR GA201/03/0091 Institutional research plan: CEZ:AV0Z5007907 Keywords : adaptive foraging * food chain * food web structure Subject RIV: EH - Ecology, Behaviour Impact factor: 1.587, year: 2003

  1. Skill ontogeny among Tsimane forager-horticulturalists.

    Science.gov (United States)

    Schniter, Eric; Gurven, Michael; Kaplan, Hillard S; Wilcox, Nathaniel T; Hooper, Paul L

    2015-09-01

    We investigate whether age profiles of Tsimane forager-horticulturalists' reported skill development are consistent with predictions derived from life history theory about the timing of productivity and reproduction. Previous studies of forager skill development have often focused on a few abilities (e.g. hunting), and neglected the broad range of skills and services typical of forager economies (e.g. childcare, craft production, music performance, story-telling). By systematically examining age patterns in reported acquisition, proficiency, and expertise across a broad range of activities including food production, childcare, and other services, we provide the most complete skill development study of a traditional subsistence society to date. Our results show that: (1) most essential skills are acquired prior to first reproduction, then developed further so that their productive returns meet the increasing demands of dependent offspring during adulthood; (2) as postreproductive adults age beyond earlier years of peak performance, they report developing additional conceptual and procedural proficiency, and despite greater physical frailty than younger adults, are consensually regarded as the most expert (especially in music and storytelling), consistent with their roles as providers and educators. We find that adults have accurate understandings of their skillsets and skill levels -an important awareness for social exchange, comparison, learning, and pedagogy. These findings extend our understanding of the evolved human life history by illustrating how changes in embodied capital and the needs of dependent offspring predict the development of complementary skills and services in a forager-horticulturalist economy. © 2015 Wiley Periodicals, Inc.

  2. Improving tree establishment with forage crops

    Science.gov (United States)

    Eric J. Holzmueller; Carl W. Mize

    2003-01-01

    Tree establishment in Iowa can be difficult without adequate weed control. Although herbicides are effective at controlling weeds, they may not be desirable in riparian settings and some landowners are opposed to using them. An alternative to herbicides is the use of forage crops to control weeds. A research project was established in 1998 to evaluate the influence of...

  3. Information Foraging in E-Voting

    DEFF Research Database (Denmark)

    Vatrapu, Ravi; Robertson, Scott

    2009-01-01

    with others. Interaction analysis of the case study data consisted of applying Information Foraging Theory to understand participant specific behaviors in searching and browsing. Case study results show skewed time allocation to activities, a tradeoff between enrichment vs. exploitation of search results...

  4. Foraging strategies of Antarctic Fulmarine petrels

    NARCIS (Netherlands)

    Creuwels, J.C.S.; Engelhard, G.A.; Franeker, van J.A.; Veer, van der W.; Hasperhoven, J.G.; Ruiterman, W.

    2010-01-01

    During breeding, procellariiform seabirds are typical central-place foragers, depending on distant pelagic resources. Especially in polar environments, where there is only a short time window to complete the breeding season, high chick provisioning rates are needed to allow chicks to fledge

  5. Optimal search behavior and classic foraging theory

    International Nuclear Information System (INIS)

    Bartumeus, F; Catalan, J

    2009-01-01

    Random walk methods and diffusion theory pervaded ecological sciences as methods to analyze and describe animal movement. Consequently, statistical physics was mostly seen as a toolbox rather than as a conceptual framework that could contribute to theory on evolutionary biology and ecology. However, the existence of mechanistic relationships and feedbacks between behavioral processes and statistical patterns of movement suggests that, beyond movement quantification, statistical physics may prove to be an adequate framework to understand animal behavior across scales from an ecological and evolutionary perspective. Recently developed random search theory has served to critically re-evaluate classic ecological questions on animal foraging. For instance, during the last few years, there has been a growing debate on whether search behavior can include traits that improve success by optimizing random (stochastic) searches. Here, we stress the need to bring together the general encounter problem within foraging theory, as a mean for making progress in the biological understanding of random searching. By sketching the assumptions of optimal foraging theory (OFT) and by summarizing recent results on random search strategies, we pinpoint ways to extend classic OFT, and integrate the study of search strategies and its main results into the more general theory of optimal foraging.

  6. Field and Forage Crop Pests. MEP 310.

    Science.gov (United States)

    Morgan, Omar, D.; And Others

    As part of a cooperative extension service series by the University of Maryland, this publication introduces the identification and control of common agricultural pests that can be found in field and forage crops. The first of the five sections defines "pest" and "weed" and generally introduces different kinds of pests in the…

  7. Alternatives for forage evaluation in ruminants

    NARCIS (Netherlands)

    Gosselink, J.M.J.

    2004-01-01

    The objective of this thesis was to validate and to compare in situ and in vitro techniques with in vivo data. These techniques were also evaluated for future and practical use in feed evaluation for ruminants. The techniques were compared using the digestion data of 98 forages and the energy

  8. Foraging behavior analysis of swarm robotics system

    Directory of Open Access Journals (Sweden)

    Sakthivelmurugan E.

    2018-01-01

    Full Text Available Swarm robotics is a number of small robots that are synchronically works together to accomplish a given task. Swarm robotics faces many problems in performing a given task. The problems are pattern formation, aggregation, Chain formation, self-assembly, coordinated movement, hole avoidance, foraging and self-deployment. Foraging is most essential part in swarm robotics. Foraging is the task to discover the item and get back into the shell. The researchers conducted foraging experiments with random-movement of robots and they have end up with unique solutions. Most of the researchers have conducted experiments using the circular arena. The shell is placed at the centre of the arena and environment boundary is well known. In this study, an attempt is made to different strategic movements like straight line approach, parallel line approach, divider approach, expanding square approach, and parallel sweep approach. All these approaches are to be simulated by using player/stage open-source simulation software based on C and C++ programming language in Linux operating system. Finally statistical comparison will be done with task completion time of all these strategies using ANOVA to identify the significant searching strategy.

  9. 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

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

    Directory of Open Access Journals (Sweden)

    Nobuo Kokubun

    Full Text Available 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

  11. Trapline foraging by bumble bees: VII. Adjustments for foraging success following competitor removal

    OpenAIRE

    Kazuharu Ohashi; Alison Leslie; James D. Thomson

    2013-01-01

    Animals collecting food from renewable resource patches scattered in space often establish small foraging areas to which they return faithfully. Such area fidelity offers foraging advantages through selection of profitable patches, route minimization, and regular circuit visits to these patches (“trapline foraging”). Resource distribution under field conditions may often vary in time, however, especially when competitors suddenly vanish and a number of patches become available for their neigh...

  12. Is there an endogenous tidal foraging rhythm in marine iguanas?

    Science.gov (United States)

    Wikelski, M; Hau, M

    1995-12-01

    As strictly herbivorous reptiles, Galápagos marine iguanas graze on algae in the intertidal areas during low tide. Daily foraging rhythms were observed on two islands during 3 years to determine the proximate factors underlying behavioral synchrony with the tides. Marine iguanas walked to their intertidal foraging grounds from far-off resting areas in anticipation of the time of low tide. Foraging activity was restricted to daytime, resulting in a complex bitidal rhythm including conspicuous switches from afternoon foraging to foraging during the subsequent morning when low tide occurred after dusk. The animals anticipated the daily low tide by a maximum of 4 h. The degree of anticipation depended on environmental parameters such as wave action and food supply. "Early foragers" survived in greater numbers than did animals arriving later at foraging sites, a result indicating selection pressure on the timing of anticipation. The timing of foraging trips was better predicted by the daily changes in tabulated low tide than it was by the daily changes in actual exposure of the intertidal foraging flats, suggesting an endogenous nature of the foraging rhythms. Endogenous rhythmicity would also explain why iguanas that had spontaneously fasted for several days nevertheless went foraging at the "right" time of day. A potential lunar component of the foraging rhythmicity of marine iguanas showed up in their assemblage on intertidal rocks during neap tide nights. This may indicate that iguanas possessed information on the semi-monthly rhythms in tide heights. Enclosure experiments showed that bitidal foraging rhythms of iguanas may free run in the absence of direct cues from the intertidal areas and operate independent of the light:dark cycle and social stimuli. Therefore, the existence of a circatidal oscillator in marine iguanas is proposed. The bitidal foraging pattern may result from an interaction of a circadian system with a circatidal system. Food intake or related

  13. 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

  14. 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.

  15. 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.

  16. Social Learning in Vespula Germanica Wasps: Do They Use Collective Foraging Strategies?

    Science.gov (United States)

    Lozada, Mariana; D' Adamo, Paola; Buteler, Micaela; Kuperman, Marcelo N

    2016-01-01

    Vespula germanica is a social wasp that has become established outside its native range in many regions of the world, becoming a major pest in the invaded areas. In the present work we analyze social communication processes used by V. germanica when exploiting un-depleted food sources. For this purpose, we investigated the arrival pattern of wasps at a protein bait and evaluated whether a forager recruited conspecifics in three different situations: foragers were able to return to the nest (full communication), foragers were removed on arrival (communication impeded), or only one forager was allowed to return to the nest (local enhancement restricted). Results demonstrated the existence of recruitment in V. germanica, given that very different patterns of wasp arrivals and a higher frequency of wasp visits to the resource were observed when communication flow between experienced and naive foragers was allowed. Our findings showed that recruitment takes place at a distance from the food source, in addition to local enhancement. When both local enhancement and distant recruitment were occurring simultaneously, the pattern of wasp arrival was exponential. When recruitment occurred only distant from the feeder, the arrival pattern was linear, but the number of wasps arriving was twice as many as when neither communication nor local enhancement was allowed. Moreover, when return to the nest was impeded, wasp arrival at the bait was regular and constant, indicating that naive wasps forage individually and are not spatially aggregated. In conclusion, this is the first study to demonstrate recruitment in V. germanica at a distance from the food source by modelling wasps' arrival to a protein-based resource. In addition, the existence of correlations when communication was allowed and reflected in tandem arrivals indicates that we were not in the presence of random processes.

  17. Social Learning in Vespula Germanica Wasps: Do They Use Collective Foraging Strategies?

    Directory of Open Access Journals (Sweden)

    Mariana Lozada

    Full Text Available Vespula germanica is a social wasp that has become established outside its native range in many regions of the world, becoming a major pest in the invaded areas. In the present work we analyze social communication processes used by V. germanica when exploiting un-depleted food sources. For this purpose, we investigated the arrival pattern of wasps at a protein bait and evaluated whether a forager recruited conspecifics in three different situations: foragers were able to return to the nest (full communication, foragers were removed on arrival (communication impeded, or only one forager was allowed to return to the nest (local enhancement restricted. Results demonstrated the existence of recruitment in V. germanica, given that very different patterns of wasp arrivals and a higher frequency of wasp visits to the resource were observed when communication flow between experienced and naive foragers was allowed. Our findings showed that recruitment takes place at a distance from the food source, in addition to local enhancement. When both local enhancement and distant recruitment were occurring simultaneously, the pattern of wasp arrival was exponential. When recruitment occurred only distant from the feeder, the arrival pattern was linear, but the number of wasps arriving was twice as many as when neither communication nor local enhancement was allowed. Moreover, when return to the nest was impeded, wasp arrival at the bait was regular and constant, indicating that naive wasps forage individually and are not spatially aggregated. In conclusion, this is the first study to demonstrate recruitment in V. germanica at a distance from the food source by modelling wasps' arrival to a protein-based resource. In addition, the existence of correlations when communication was allowed and reflected in tandem arrivals indicates that we were not in the presence of random processes.

  18. ASAS Centennial Paper: Future needs of research and extension in forage utilization.

    Science.gov (United States)

    Rouquette, F M; Redmon, L A; Aiken, G E; Hill, G M; Sollenberger, L E; Andrae, J

    2009-01-01

    Forage-animal production agriculture is implementing infrastructure changes and management strategies to adjust to increased energy-related costs of fuel, feed grains, fertilizers, and seeds. The primary objectives of this position paper are to assess future research and extension scientific needs in forage utilization, financial support for the discipline, and changing status and number of scientists. A survey questionnaire returned from 25 land-grant universities in the eastern half of the United States rated the top 4 research needs as 1) pasture systems and efficiency of production; 2) interfacing with energy concerns; 3) forage cultivar evaluations and persistence; and 4) environment impacts. Plant-animal future research needs at 11 USDA-ARS regional locations are targeted at sustainable management and improved livestock performance, ecophysiology and ecology of grasslands, environment impacts, and improved technologies for nutritive value assessments. Extension scientists from 17 southern and northeastern states listed the top 3 needs as forage persistence, soil fertility and nutrient management, and pasture systems and efficiency of production. Grant funds currently provide more than 40% of land-grant university research and extension efforts in forage utilization, and scientists estimate that this support base will increase to 55 to 60% of the funding total by 2013. Reduced allocation of state and federal funding has contributed to a reduction in the number of full-time equivalent (FTE) scientists engaged in forage utilization research and extension activities. The current 25 state FTE conducting research number about 2.8 per state. This includes 10 states with >3, 11 states with research Extension programming, and technology transfer methods will change to accommodate reduced funding but with increasing numbers of novice, recreation-oriented landowners.

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

    Directory of Open Access Journals (Sweden)

    Balaji Prabhakar

    Full Text Available 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.

  20. Volume and density of microglomeruli in the honey bee mushroom bodies do not predict performance on a foraging task.

    Science.gov (United States)

    Van Nest, Byron N; Wagner, Ashley E; Marrs, Glen S; Fahrbach, Susan E

    2017-09-01

    The mushroom bodies (MBs) are insect brain regions important for sensory integration, learning, and memory. In adult worker honey bees (Apis mellifera), the volume of neuropil associated with the MBs is larger in experienced foragers compared with hive bees and less experienced foragers. In addition, the characteristic synaptic structures of the calycal neuropils, the microglomeruli, are larger but present at lower density in 35-day-old foragers relative to 1-day-old workers. Age- and experience-based changes in plasticity of the MBs are assumed to support performance of challenging tasks, but the behavioral consequences of brain plasticity in insects are rarely examined. In this study, foragers were recruited from a field hive to a patch comprising two colors of otherwise identical artificial flowers. Flowers of one color contained a sucrose reward mimicking nectar; flowers of the second were empty. Task difficulty was adjusted by changing flower colors according to the principle of honey bee color vision space. Microglomerular volume and density in the lip (olfactory inputs) and collar (visual inputs) compartments of the MB calyces were analyzed using anti-synapsin I immunolabeling and laser scanning confocal microscopy. Foragers displayed significant variation in microglomerular volume and density, but no correlation was found between these synaptic attributes and foraging performance. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1057-1071, 2017. © 2017 Wiley Periodicals, Inc.

  1. Visual perception and social foraging in birds.

    Science.gov (United States)

    Fernández-Juricic, Esteban; Erichsen, Jonathan T; Kacelnik, Alex

    2004-01-01

    Birds gather information about their environment mainly through vision by scanning their surroundings. Many prevalent models of social foraging assume that foraging and scanning are mutually exclusive. Although this assumption is valid for birds with narrow visual fields, these models have also been applied to species with wide fields. In fact, available models do not make precise predictions for birds with large visual fields, in which the head-up, head-down dichotomy is not accurate and, moreover, do not consider the effects of detection distance and limited attention. Studies of how different types of visual information are acquired as a function of body posture and of how information flows within flocks offer new insights into the costs and benefits of living in groups.

  2. 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

  3. 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

  4. Utilization of 15N in the sequence of mineral fertilizer - forage - animal - slurry - forage

    International Nuclear Information System (INIS)

    Peschke, H.

    1981-01-01

    After systematic application of 15 N-ammonium nitrate, the change of the dinuclidic composition and 15 N quantity was studied by isotope analysis of several open systems in the sequence mineral fertilizer - (soil) - forage - (animal) - slurry - (soil) - forage. The relative 15 N isotope frequency of 50 atom% in the mineral fertilizer declined to 12.2 to 21.4 atom% in the forage (beet, oats, hay) and went down to 3.15 atom% in the slurry of a dairy cow fed on this forage. Silage maize manured with the slurry of the dairy cow only showed 1.98 atom %, green oats grown after the silage maize on the same area was found to have 0.45 atom%. The 15 N quantity of 104.5 g N in the fertilizer gradually decreased to 41.6 g N in the forage, 30.5 g N in the slurry and 22.6 g N in the silage maize. The causes discussed are 15 N isotope dilution as qualitative factor and productive and unproductive N losses as quantitative factors. (author)

  5. Hybrid value foraging: How the value of targets shapes human foraging behavior.

    Science.gov (United States)

    Wolfe, Jeremy M; Cain, Matthew S; Alaoui-Soce, Abla

    2018-04-01

    In hybrid foraging, observers search visual displays for multiple instances of multiple target types. In previous hybrid foraging experiments, although there were multiple types of target, all instances of all targets had the same value. Under such conditions, behavior was well described by the marginal value theorem (MVT). Foragers left the current "patch" for the next patch when the instantaneous rate of collection dropped below their average rate of collection. An observer's specific target selections were shaped by previous target selections. Observers were biased toward picking another instance of the same target. In the present work, observers forage for instances of four target types whose value and prevalence can vary. If value is kept constant and prevalence manipulated, participants consistently show a preference for the most common targets. Patch-leaving behavior follows MVT. When value is manipulated, observers favor more valuable targets, though individual foraging strategies become more diverse, with some observers favoring the most valuable target types very strongly, sometimes moving to the next patch without collecting any of the less valuable targets.

  6. Utilization of /sup 15/N in the sequence of mineral fertilizer - forage - animal - slurry - forage

    Energy Technology Data Exchange (ETDEWEB)

    Peschke, H [Humboldt-Universitaet, Berlin (German Democratic Republic). Sektion Pflanzenproduktion

    1981-12-01

    After systematic application of /sup 15/N-ammonium nitrate, the change of the dinuclidic composition and /sup 15/N quantity was studied by isotope analysis of several open systems in the sequence mineral fertilizer - (soil) - forage - (animal) - slurry - (soil) - forage. The relative /sup 15/N isotope frequency of 50 atom% in the mineral fertilizer declined to 12.2 to 21.4 atom% in the forage (beet, oats, hay) and went down to 3.15 atom% in the slurry of a dairy cow fed on this forage. Silage maize manured with the slurry of the dairy cow only showed 1.98 atom %, green oats grown after the silage maize on the same area was found to have 0.45 atom%. The /sup 15/N quantity of 104.5 g N in the fertilizer gradually decreased to 41.6 g N in the forage, 30.5 g N in the slurry and 22.6 g N in the silage maize. The causes discussed are /sup 15/N isotope dilution as qualitative factor and productive and unproductive N losses as quantitative factors.

  7. Protein Binding Capacity of Different Forages Tannin

    Science.gov (United States)

    Yusiati, L. M.; Kurniawati, A.; Hanim, C.; Anas, M. A.

    2018-02-01

    Eight forages of tannin sources(Leucaena leucocephala, Arachis hypogaea, Mimosa pudica, Morus alba L, Swietenia mahagoni, Manihot esculenta, Gliricidia sepium, and Bauhinia purpurea)were evaluated their tannin content and protein binding capacity. The protein binding capacity of tannin were determined using precipitation of bovine serum albumin (BSA). Swietenia mahagonihas higest total tannin level and condensed tannin (CT) compared with other forages (P<0.01). The Leucaena leucocephala has highest hydrolysable tannin (HT) level (P<0.01). The total and condensed tannin content of Swietenia mahagoni were 11.928±0.04 mg/100 mg and 9.241±0.02mg/100mg dry matter (DM) of leaves. The hydrolysable tannin content of Leucaena leucocephala was 5.338±0.03 mg/100 mg DM of leaves. Binding capacity was highest in Swietenia mahagoni and Leucaena leucocephala compared to the other forages (P<0.01). The optimum binding of BSA to tannin in Leucaena leucocephala and Swietenia mahagoniwere1.181±0.44 and 1.217±0.60mg/mg dry matter of leaves. The present study reports that Swietenia mahagoni has highest of tannin content and Leucaena leucocephala and Swietenia mahagoni capacity of protein binding.

  8. Mercury in San Francisco Bay forage fish

    Energy Technology Data Exchange (ETDEWEB)

    Greenfield, Ben K., E-mail: ben@sfei.or [San Francisco Estuary Institute, 7770 Pardee Lane, Oakland, CA 94621 (United States); Jahn, Andrew, E-mail: andyjahn@mac.co [1000 Riverside Drive, Ukiah, CA 95482 (United States)

    2010-08-15

    In the San Francisco Estuary, management actions including tidal marsh restoration could change fish mercury (Hg) concentrations. From 2005 to 2007, small forage fish were collected and analyzed to identify spatial and interannual variation in biotic methylmercury (MeHg) exposure. The average whole body total Hg concentration was 0.052 {mu}g g{sup -1} (wet-weight) for 457 composite samples representing 13 fish species. MeHg constituted 94% of total Hg. At a given length, Hg concentrations were higher in nearshore mudflat and wetland species (Clevelandia ios, Menidia audens, and Ilypnus gilberti), compared to species that move offshore (e.g., Atherinops affinis and Lepidogobius lepidus). Gut content analysis indicated similar diets between Atherinops affinis and Menidia audens, when sampled at the same locations. Hg concentrations were higher in sites closest to the Guadalupe River, which drains a watershed impacted by historic Hg mining. Results demonstrate that despite differences among years and fish species, nearshore forage fish exhibit consistent Hg spatial gradients. - Total mercury in estuarine forage fish varies with species, habitat, and proximity to a historic mercury mine.

  9. Nutritional characteristics of forages from Niger

    Directory of Open Access Journals (Sweden)

    F. Infascelli

    2010-04-01

    Full Text Available In the production systems of the semi-arid areas low quality forages are commonly used as the basal diet (Wilkins, 2000 and, as a consequence, the nutritional status of ruminants depends mainly on the ability of rumen fermentation to yield nutrients such as the short chain fatty acids and microbial biomass (Preston and Leng, 1987. The forages browsed by the livestock can be classified into two main groups: ephemeral annual plants, which germinate and remain green for only a few weeks after rain, perennial shrubs and tree fodders. Despite their potential as feeds, little research has determined their nutritive value. In vivo evaluation is the best estimation method of feed’s nutritional value, however it is very laborious and difficult to standardize with browsing animals. O the contrary, in vitro methods are less expensive, less time consuming and allow a better control of experimental conditions than in vivo experiments. The in vitro gas production technique (IVGPT appears to be the most suitable method for use in developing countries where resources may be limited (Makkar, 2004. Increased interest in use of non-conventional feed resources has led to an increase in use of this technique, since IVGPT can provide useful data on digestion kinetics of both the soluble and insoluble fractions of feedstuffs. The aim of the present research was to evaluate twelve forages from the arid zone of Niger using the IVGPT.

  10. Mercury in San Francisco Bay forage fish

    International Nuclear Information System (INIS)

    Greenfield, Ben K.; Jahn, Andrew

    2010-01-01

    In the San Francisco Estuary, management actions including tidal marsh restoration could change fish mercury (Hg) concentrations. From 2005 to 2007, small forage fish were collected and analyzed to identify spatial and interannual variation in biotic methylmercury (MeHg) exposure. The average whole body total Hg concentration was 0.052 μg g -1 (wet-weight) for 457 composite samples representing 13 fish species. MeHg constituted 94% of total Hg. At a given length, Hg concentrations were higher in nearshore mudflat and wetland species (Clevelandia ios, Menidia audens, and Ilypnus gilberti), compared to species that move offshore (e.g., Atherinops affinis and Lepidogobius lepidus). Gut content analysis indicated similar diets between Atherinops affinis and Menidia audens, when sampled at the same locations. Hg concentrations were higher in sites closest to the Guadalupe River, which drains a watershed impacted by historic Hg mining. Results demonstrate that despite differences among years and fish species, nearshore forage fish exhibit consistent Hg spatial gradients. - Total mercury in estuarine forage fish varies with species, habitat, and proximity to a historic mercury mine.

  11. The Effects of Forage Policy on Feed Costs in Korea

    Directory of Open Access Journals (Sweden)

    Jae Bong Chang

    2018-05-01

    Full Text Available Feeding operations are substantial on livestock farms, besides being potentially expensive. Feeding efficiency has been considered a major influence on profits in the livestock industry. Indeed, feed costs are shown to be the largest single item of production cost in Korea. To promote production and use of domestic forage, the Korean government has enforced the forage base expansion program that strengthens the competitiveness of the livestock industry by reducing the production cost. The forage base expansion program includes three main policies: subsidized forage production, support for processing and distribution, and expanding land for forage production. This paper investigates the influence of the government’s policies often conjectured to have pronounced effects on forage production. To evaluate the forage policies, this paper uses a path-analysis approach linking government spending on forage base expansion programs and feed costs. Results indicate that the Korean government’s spending on supporting domestic forage production results in a decrease in the ratio of forage expenses to total feed cost.

  12. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2003-01-01

    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

  14. 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

  15. 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.

  16. 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.

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

    International Nuclear Information System (INIS)

    Armelin, Maria Jose A.; Saiki, Mitiko; Primavesi, Odo; Primavesi, Ana C.

    2007-01-01

    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 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)

  18. Work or sleep? : honeybee foragers opportunistically nap during the day when forage is not available

    OpenAIRE

    Klein, Barrett; Seeley, Thomas D.

    2011-01-01

    Shifts in work schedules test humans’ capacity to be flexible in the timing of both work and sleep. Honeybee, Apis mellifera, foragers also shift their work schedules, but how flexible they are in the timing of sleep as they shift the timing of work is unknown, despite the importance of colony-level plasticity in the face of a changing environment. We hypothesized that sleep schedules of foragers are not fixed and instead vary depending on the time when food is available. We trained bees to v...

  19. Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

    Directory of Open Access Journals (Sweden)

    Raquel Santiago Barro

    2012-07-01

    Full Text Available The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum and a forage legume (Arachis pintoi under two shading levels compared with full sun. The experiment was conducted in the Campanha region, Bagé, state of Rio Grande do Sul, Brazil, during two evaluation cycles (2008/2009 and 2009/2010. Three shade cloth levels (0%, 50% and 80% of light restriction were applied to the forage genotypes in a split plot design, in which shading levels were the main plot and forage genotypes were the subplots, with three replications. P. regnellii showed the highest accumulated DMY (1500 and 1700 g m-2, respectively, for the first and second evaluation cycles at all shading levels and showed no DMY decreased under the heavy shade (80%. Average DMY over the four genotypes under the 50% shade level was higher or equal compared with full sun. Influence of rainfall was observed on the DMY performance of all genotypes: the positive effect of moderate shading (50% on P. dilatatum and P. notatum DMY was associated to a low soil water availability status. Increased shading level resulted in high nitrogen nutrition index values on grasses, in comparison with full sun. All genotypes performed well under the moderate shading level, but the DMY of both P. regnellii and P. dilatatum and the herbage N content in P. notatum and A. pintoi of all genotypes stood out, showing that those main genotypes are promising to grow in silvopastoral systems at the Campanha region in southern Brazil.

  20. Review: Feeding conserved forage to horses: recent advances and recommendations.

    Science.gov (United States)

    Harris, P A; Ellis, A D; Fradinho, M J; Jansson, A; Julliand, V; Luthersson, N; Santos, A S; Vervuert, I

    2017-06-01

    The horse is a non-ruminant herbivore adapted to eating plant-fibre or forage-based diets. Some horses are stabled for most or the majority of the day with limited or no access to fresh pasture and are fed preserved forage typically as hay or haylage and sometimes silage. This raises questions with respect to the quality and suitability of these preserved forages (considering production, nutritional content, digestibility as well as hygiene) and required quantities. Especially for performance horses, forage is often replaced with energy dense feedstuffs which can result in a reduction in the proportion of the diet that is forage based. This may adversely affect the health, welfare, behaviour and even performance of the horse. In the past 20 years a large body of research work has contributed to a better and deeper understanding of equine forage needs and the physiological and behavioural consequences if these are not met. Recent nutrient requirement systems have incorporated some, but not all, of this new knowledge into their recommendations. This review paper amalgamates recommendations based on the latest understanding in forage feeding for horses, defining forage types and preservation methods, hygienic quality, feed intake behaviour, typical nutrient composition, digestion and digestibility as well as health and performance implications. Based on this, consensual applied recommendations for feeding preserved forages are provided.

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. Comparison of sorghum classes for grain and forage yield and forage nutritive value

    Science.gov (United States)

    Sorghum represents a broad category of plants that includes those grown primarily for forage (FS) or grain. Sorghum sudan crosses (SS) are also considered sorghum. Each of these groups can be further classified as brown midrib (BMR), nonBMR, photoperiod sensitive (PS), and nonPS. In our study, sor...

  6. 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...

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 75 FR 68321 - Forage Genetics International; Supplemental Request for Partial Deregulation of Roundup Ready...

    Science.gov (United States)

    2010-11-05

    ...] Forage Genetics International; Supplemental Request for Partial Deregulation of Roundup Ready Alfalfa... Inspection Service has received a supplemental request for ``partial deregulation'' from Forage Genetics... affected persons of the availability of the documents submitted to the Agency from Forage Genetics...

  13. 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)

  14. Utilization of male sterility in forage crops

    International Nuclear Information System (INIS)

    Suginobu, Ken-ichi

    1982-01-01

    The genetic nature of male sterility in forage crops was reviewed. Many workers have suggested that hybrids in forage crops are quite promising. First, the selection of the most desirable parental genotype from a large original population is improtant in heterosis breeding programs. After the more promising inbreds or clones have been selected on the basis of good general combining ability, it is necessary to identify the particular single, three-way or double cross that will produce the highest yields. A high seed yield potential is also important in a new variety so that the seeds can be sold at lower prices than other varieties. A tentative scheme for hybrid seed production by using inbred lines of male sterile or normal parents is proposed. At a breeding station, the seeds for male sterile F 1 (AB), maintainer S 1 (C-S 1 ) and either maintainer or restorer S 1 s(D-S 1 , E-S 1 ) are produced from the parental clones. At a seed increase agency, the seeds for male sterile F 1 (ABC) and either maintainer or restorer S 2 (D-S 2 ) are produced. In the case that D-S 2 seed production is difficult, maintainer or restorer F 1 (DE) should be produced from D-S 1 x E-S 1 . These seeds are used for commercial seed production. Seeds of hybrid F 1 (ABCD) or hybrid F 1 (ABCDE) are for practical use. (Kaihara, S.)

  15. 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.

  16. Seed storage effects on germination for two forage kochia cultivars

    Science.gov (United States)

    The cultivar ‘Snowstorm’ forage kochia was released by the USDA-ARS in 2012. It is a synthetic cultivar selected for stature, forage production, and adaptation to semiarid environments. Similar to the earlier released (1984) ‘Immigrant’ cultivar it can increase rangeland productivity magnitudes when...

  17. Forage yield and quality of kenaf ( Hibiscus cannabinus L.) for ...

    African Journals Online (AJOL)

    This study was carried out to evaluate 40 kenaf accessions for forage yield and quality at Universiti Putra Malaysia in 2009. Forage yield and quality traits were measured at the initial flowering stage. The kenaf accessions showed highly significant variation for most of trait studied. Plant dry matter yield ranged from 5286 kg ...

  18. 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. PMID:24194958

  19. Morphological responses of forage sorghums to salinity and ...

    African Journals Online (AJOL)

    The response of forage sorghum [Sorghum bicolor (L.) Moench] varieties to salinity and irrigation frequency were studied from December 2007 to December 2009. Two forage sorghum varieties (Speedfeed and KFS4) were grown under salinity levels of 0, 5, 10 and 15 dS m-1 and irrigated when the leaf water potential ...

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Wenchao Yang

    Full Text Available 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.

  2. Effects of seasonal advancement on the forage availability, quality ...

    African Journals Online (AJOL)

    Effects of seasonal advancement on the forage availability, quality and acceptability by grazing gudali cattle in the humid zone of Nigeria. ... There were significant (p<0.05) differences in the dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) contents of all the forages. DM content ranged from 9.6% (Tridax ...

  3. 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

  4. Honeybee forage, bee visitation counts and the properties of honey ...

    African Journals Online (AJOL)

    The aim of the survey was to document honeybee forage plants and asses honeybee visitation counts on different forage plants and properties of honey from selected agro-ecological zones of Uganda. In order to achieve the objectives of the study, a survey of the apiaries and beekeepers was done by selecting fifteen bee ...

  5. Does supplemental feeding affect behaviour and foraging of ...

    African Journals Online (AJOL)

    In response to the provision of high-quality pods of Acacia albida, animals reduced foraging time in 2008 and allocated it to resting. This pattern corresponds to the animals' behaviour in captivity without foraging versus vigilance trade-offs and with predictable (in time and space) access to food. In 2009, supplemental ...

  6. Forage herbs improve mineral composition of grassland herbage

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

  7. 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…

  8. Testing Optimal Foraging Theory Using Bird Predation on Goldenrod Galls

    Science.gov (United States)

    Yahnke, Christopher J.

    2006-01-01

    All animals must make choices regarding what foods to eat, where to eat, and how much time to spend feeding. Optimal foraging theory explains these behaviors in terms of costs and benefits. This laboratory exercise focuses on optimal foraging theory by investigating the winter feeding behavior of birds on the goldenrod gall fly by comparing…

  9. Foraging behaviour and feeding ecology of the Black-cheeked ...

    African Journals Online (AJOL)

    Foraging behaviour and feeding ecology of the Black-cheeked Lovebird Agapornis nigrigenis were studied in Zambia. The birds fed on at least 39 species, and food items included seeds, leaves, flowers (especially nectar), fruit pulp, invertebrates, bark, lichen and resin. Terrestrial foraging was dominant, whereas arboreal ...

  10. 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.

  11. Boldness affects foraging decisions in barnacle geese: an experimental approach

    NARCIS (Netherlands)

    Kurvers, R.H.J.M.; Nolet, B.A.; Prins, H.H.T.; Ydenberg, R.C.; Oers, van K.

    2012-01-01

    Individuals foraging in groups constantly need to make decisions, such as when to leave a group, when to join a group, and when to move collectively to another feeding site. In recent years, it has become evident that personality may affect these foraging decisions, but studies where individuals are

  12. Scavenger: Transparent Development of Efficient Cyber Foraging Applications

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø

    2010-01-01

    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...

  13. Optimal Foraging for Multiple Resources in Several Food Species

    NARCIS (Netherlands)

    Hengeveld, G.M.; Langevelde, van F.; Groen, T.A.; Knegt, de H.J.

    2009-01-01

    The concentrations of resources in forage are not perfectly balanced to the needs of an animal, and food species differ in these concentrations. Under many circumstances, animals should thus forage on multiple food species to attain the maximum and most balanced intake of several resources. In this

  14. Optimal foraging for multiple resources in several food species

    NARCIS (Netherlands)

    Hengeveld, G.M.; van Langevelde, F.; Groen, T.A.; de Knegt, H.J.

    2009-01-01

    The concentrations of resources in forage are not perfectly balanced to the needs of an animal, and food species differ in these concentrations. Under many circumstances, animals should thus forage on multiple food species to attain the maximum and most balanced intake of several resources. In this

  15. 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.

  16. Improving the Yield and Nutritional Quality of Forage Crops

    Directory of Open Access Journals (Sweden)

    Nicola M. Capstaff

    2018-04-01

    Full Text Available Despite being some of the most important crops globally, there has been limited research on forages when compared with cereals, fruits, and vegetables. This review summarizes the literature highlighting the significance of forage crops, the current improvements and some of future directions for improving yield and nutritional quality. We make the point that the knowledge obtained from model plant and grain crops can be applied to forage crops. The timely development of genomics and bioinformatics together with genome editing techniques offer great scope to improve forage crops. Given the social, environmental and economic importance of forage across the globe and especially in poorer countries, this opportunity has enormous potential to improve food security and political stability.

  17. Spatial variation in foraging behaviour of a marine top predator (Phoca vitulina determined by a large-scale satellite tagging program.

    Directory of Open Access Journals (Sweden)

    Ruth J Sharples

    Full Text Available The harbour seal (Phoca vitulina is a widespread marine predator in Northern Hemisphere waters. British populations have been subject to rapid declines in recent years. Food supply or inter-specific competition may be implicated but basic ecological data are lacking and there are few studies of harbour seal foraging distribution and habits. In this study, satellite tagging conducted at the major seal haul outs around the British Isles showed both that seal movements were highly variable among individuals and that foraging strategy appears to be specialized within particular regions. We investigated whether these apparent differences could be explained by individual level factors: by modelling measures of trip duration and distance travelled as a function of size, sex and body condition. However, these were not found to be good predictors of foraging trip duration or distance, which instead was best predicted by tagging region, time of year and inter-trip duration. Therefore, we propose that local habitat conditions and the constraints they impose are the major determinants of foraging movements. Specifically the distance to profitable feeding grounds from suitable haul-out locations may dictate foraging strategy and behaviour. Accounting for proximity to productive foraging resources is likely to be an important component of understanding population processes. Despite more extensive offshore movements than expected, there was also marked fidelity to the local haul-out region with limited connectivity between study regions. These empirical observations of regional exchange at short time scales demonstrates the value of large scale electronic tagging programs for robust characterization of at-sea foraging behaviour at a wide spatial scale.

  18. Is Bumblebee Foraging Efficiency Mediated by Morphological Correspondence to Flowers?

    Directory of Open Access Journals (Sweden)

    Ikumi Dohzono

    2011-01-01

    Full Text Available Preference for certain types of flowers in bee species may be an adaptation for efficient foraging, and they often prefer flowers whose shape fits their mouthparts. However, it is unclear whether such flowers are truly beneficial for them. We address this issue by experimentally measuring foraging efficiency of bumblebees, the volume of sucrose solution consumed over handling time (μL/second, using long-tongued Bombus diversus Smith and short-tongued B. honshuensis Tkalcu that visit Clematis stans Siebold et Zuccarini. The corolla tube length of C. stans decreases during a flowering period, and male flowers are longer than female flowers. Long- and short-tongued bumblebees frequently visited longer and shorter flowers, respectively. Based on these preferences, we hypothesized that bumblebee foraging efficiency is higher when visiting flowers that show a good morphological fit between the proboscis and the corolla tube. Foraging efficiency of bumblebees was estimated using flowers for which nectar quality and quantity were controlled, in an experimental enclosure. We show that 1 the foraging efficiency of B. diversus was enhanced when visiting younger, longer flowers, and that 2 the foraging efficiency of B. honshuensis was higher when visiting shorter female flowers. This suggests that morphological correspondence between insects and flowers is important for insect foraging efficiency. However, in contradiction to our prediction, 3 short-tongued bumblebees B. honshuensis sucked nectar more efficiently when visiting younger, longer flowers, and 4 there was no significant difference in the foraging efficiency of B. diversus between flower sexes. These results suggest that morphological fit between the proboscis and the corolla tube is not a sole determinant of foraging efficiency. Bumblebees may adjust their sucking behavior in response to available rewards, and competition over rewards between bumblebee species might change visitation patterns

  19. Reproductive biology of the native forage grass Trichloris crinita (Poaceae, Chloridoideae).

    Science.gov (United States)

    Kozub, P C; Barboza, K; Galdeano, F; Quarin, C L; Cavagnaro, J B; Cavagnaro, P F

    2017-05-01

    Trichloris crinita is a perennial forage grass species native to arid regions of the American continent. Due to its extensive area of distribution, good forage quality and resistance to drought and grazing, this species is widely utilised as forage and for revegetation purposes in environments with low water availability. Despite its importance, genetic improvement of T. crinita has been very limited, partly as consequence of the lack of knowledge on its mode of reproduction. In the present work, we studied the reproductive biology of T. crinita by means of embryological analyses, flow cytometric seed screen (FCSS), self-compatibility tests and progeny testing with morphological and molecular markers. Cytological analyses revealed embryo sacs with eight nuclei and of Polygonum type for all T. crinita accessions analysed. FCSS histograms exhibited two clear peaks corresponding to 2C and 3C DNA content, indicating embryo sacs of sexual origin. Controlled pollination experiments designed to evaluate seed set (%) demonstrated that T. crinita is self-compatible, whereas results from morphological and simple sequence repeat (SSR) marker analysis of progeny revealed lack of outcrossing. Together, these results indicate that T. crinita reproduces sexually. It is a self-compatible and autogamous species. It is expected that these data will have a positive impact in the genetics and breeding of this species, and therefore contribute to its proper utilisation in arid regions. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

  20. 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

    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

  1. Subjective costs drive overly patient foraging strategies in rats on an intertemporal foraging task

    OpenAIRE

    Wikenheiser, Andrew M.; Stephens, David W.; Redish, A. David

    2013-01-01

    Laboratory studies of decision making often take the form of two-alternative, forced-choice paradigms. In natural settings, however, many decision problems arise as stay/go choices. We designed a foraging task to test intertemporal decision making in rats via stay/go decisions. Subjects did not follow the rate-maximizing strategy of choosing only food items associated with short delays. Instead, rats were often willing to wait for surprisingly long periods, and consequently earned a lower rat...

  2. Radionuclide transfer from forage plants into milk

    Energy Technology Data Exchange (ETDEWEB)

    Heeschen, W

    1987-06-09

    There is a lot of information regarding the transfer of radionuclides (iodine, caesium, strontium) which allows the transfer factor being calculated with high certainty. The transfer coefficients (forage-)plant/milk laid down in Paragraph 45 of the Radiation Protection Ordinance (Strahlenschutzverordnung) amount to 1.0x10/sup -2/ for iodine-131, 1.2x10/sup -2/ for caesium-137 and 2.0x10/sup -3/ for strontium-90. More recent calculated factors are markedly lower at the average. During milk processing, the greatest amount of radionuclides gets access to the whey or into the permeate after ultrafiltration of whey. In butter and cheese only minute amounts of caesium can be expected.

  3. 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.

  4. A neural coding scheme reproducing foraging trajectories

    Science.gov (United States)

    Gutiérrez, Esther D.; Cabrera, Juan Luis

    2015-12-01

    The movement of many animals may follow Lévy patterns. The underlying generating neuronal dynamics of such a behavior is unknown. In this paper we show that a novel discovery of multifractality in winnerless competition (WLC) systems reveals a potential encoding mechanism that is translatable into two dimensional superdiffusive Lévy movements. The validity of our approach is tested on a conductance based neuronal model showing WLC and through the extraction of Lévy flights inducing fractals from recordings of rat hippocampus during open field foraging. Further insights are gained analyzing mice motor cortex neurons and non motor cell signals. The proposed mechanism provides a plausible explanation for the neuro-dynamical fundamentals of spatial searching patterns observed in animals (including humans) and illustrates an until now unknown way to encode information in neuronal temporal series.

  5. Utilization of male sterility in forage crops

    Energy Technology Data Exchange (ETDEWEB)

    Suginobu, Ken-ichi [National Grassland Research Inst., Nishinasuno, Tochigi (Japan)

    1982-03-01

    The genetic nature of male sterility in forage crops was reviewed. Many workers have suggested that hybrids in forage crops are quite promising. First, the selection of the most desirable parental genotype from a large original population is improtant in heterosis breeding programs. After the more promising inbreds or clones have been selected on the basis of good general combining ability, it is necessary to identify the particular single, three-way or double cross that will produce the highest yields. A high seed yield potential is also important in a new variety so that the seeds can be sold at lower prices than other varieties. A tentative scheme for hybrid seed production by using inbred lines of male sterile or normal parents is proposed. At a breeding station, the seeds for male sterile F/sub 1/(AB), maintainer S/sub 1/(C-S/sub 1/) and either maintainer or restorer S/sub 1/s(D-S/sub 1/, E-S/sub 1/) are produced from the parental clones. At a seed increase agency, the seeds for male sterile F/sub 1/(ABC) and either maintainer or restorer S/sub 2/(D-S/sub 2/) are produced. In the case that D-S/sub 2/ seed production is difficult, maintainer or restorer F/sub 1/(DE) should be produced from D-S/sub 1/ x E-S/sub 1/. These seeds are used for commercial seed production. Seeds of hybrid F/sub 1/(ABCD) or hybrid F/sub 1/(ABCDE) are for practical use.

  6. Foraging niche segregation in Malaysian babblers (Family: Timaliidae)

    Science.gov (United States)

    Mansor, Mohammad Saiful; Ramli, Rosli

    2017-01-01

    Tropical rainforests are considered as hotspots for bird diversity, yet little is known about the system that upholds the coexistence of species. Differences in body size that are associated with foraging strategies and spatial distribution are believed to promote the coexistence of closely related species by reducing competition. However, the fact that many babbler species do not differ significantly in their morphology has challenged this view. We studied the foraging ecology of nine sympatric babbler species (i.e., Pellorneum capistratum, P. bicolor, P. malaccense, Malacopteron cinereum, M. magnum, Stachyris nigriceps, S. nigricollis, S. maculata, and Cyanoderma erythropterum) in the Krau Wildlife Reserve in Peninsular Malaysia. We investigated; i) how these babblers forage in the wild and use vegetation to obtain food, and ii) how these trophically similar species differ in spatial distribution and foraging tactics. Results indicated that most babblers foraged predominantly on aerial leaf litter and used gleaning manoeuvre in intermediate-density foliage but exhibited wide ranges of vertical strata usage, thus reducing interspecific competition. The principal component analysis indicated that two components, i.e., foraging height and substrate are important as mechanisms to allow the coexistence of sympatric babblers. The present findings revealed that these bird species have unique foraging niches that are distinct from each other, and this may apply to other insectivorous birds inhabiting tropical forests. This suggests that niche separation does occur among coexisting birds, thus following Gause’ law of competitive exclusion, which states two species occupying the same niche will not stably coexist. PMID:28253284

  7. Foraging niche segregation in Malaysian babblers (Family: Timaliidae.

    Directory of Open Access Journals (Sweden)

    Mohammad Saiful Mansor

    Full Text Available Tropical rainforests are considered as hotspots for bird diversity, yet little is known about the system that upholds the coexistence of species. Differences in body size that are associated with foraging strategies and spatial distribution are believed to promote the coexistence of closely related species by reducing competition. However, the fact that many babbler species do not differ significantly in their morphology has challenged this view. We studied the foraging ecology of nine sympatric babbler species (i.e., Pellorneum capistratum, P. bicolor, P. malaccense, Malacopteron cinereum, M. magnum, Stachyris nigriceps, S. nigricollis, S. maculata, and Cyanoderma erythropterum in the Krau Wildlife Reserve in Peninsular Malaysia. We investigated; i how these babblers forage in the wild and use vegetation to obtain food, and ii how these trophically similar species differ in spatial distribution and foraging tactics. Results indicated that most babblers foraged predominantly on aerial leaf litter and used gleaning manoeuvre in intermediate-density foliage but exhibited wide ranges of vertical strata usage, thus reducing interspecific competition. The principal component analysis indicated that two components, i.e., foraging height and substrate are important as mechanisms to allow the coexistence of sympatric babblers. The present findings revealed that these bird species have unique foraging niches that are distinct from each other, and this may apply to other insectivorous birds inhabiting tropical forests. This suggests that niche separation does occur among coexisting birds, thus following Gause' law of competitive exclusion, which states two species occupying the same niche will not stably coexist.

  8. Foraging niche segregation in Malaysian babblers (Family: Timaliidae).

    Science.gov (United States)

    Mansor, Mohammad Saiful; Ramli, Rosli

    2017-01-01

    Tropical rainforests are considered as hotspots for bird diversity, yet little is known about the system that upholds the coexistence of species. Differences in body size that are associated with foraging strategies and spatial distribution are believed to promote the coexistence of closely related species by reducing competition. However, the fact that many babbler species do not differ significantly in their morphology has challenged this view. We studied the foraging ecology of nine sympatric babbler species (i.e., Pellorneum capistratum, P. bicolor, P. malaccense, Malacopteron cinereum, M. magnum, Stachyris nigriceps, S. nigricollis, S. maculata, and Cyanoderma erythropterum) in the Krau Wildlife Reserve in Peninsular Malaysia. We investigated; i) how these babblers forage in the wild and use vegetation to obtain food, and ii) how these trophically similar species differ in spatial distribution and foraging tactics. Results indicated that most babblers foraged predominantly on aerial leaf litter and used gleaning manoeuvre in intermediate-density foliage but exhibited wide ranges of vertical strata usage, thus reducing interspecific competition. The principal component analysis indicated that two components, i.e., foraging height and substrate are important as mechanisms to allow the coexistence of sympatric babblers. The present findings revealed that these bird species have unique foraging niches that are distinct from each other, and this may apply to other insectivorous birds inhabiting tropical forests. This suggests that niche separation does occur among coexisting birds, thus following Gause' law of competitive exclusion, which states two species occupying the same niche will not stably coexist.

  9. Floral odor learning within the hive affects honeybees' foraging decisions

    Science.gov (United States)

    Arenas, Andrés; Fernández, Vanesa M.; Farina, Walter M.

    2007-03-01

    Honeybees learn odor cues quickly and efficiently when visiting rewarding flowers. Memorization of these cues facilitates the localization and recognition of food sources during foraging flights. Bees can also use information gained inside the hive during social interactions with successful foragers. An important information cue that can be learned during these interactions is food odor. However, little is known about how floral odors learned in the hive affect later decisions of foragers in the field. We studied the effect of food scent on foraging preferences when this learning is acquired directly inside the hive. By using in-hive feeders that were removed 24 h before the test, we showed that foragers use the odor information acquired during a 3-day stimulation period with a scented solution during a food-choice situation outside the nest. This bias in food preference is maintained even 24 h after the replacement of all the hive combs. Thus, without being previously collected outside by foragers, food odors learned within the hive can be used during short-range foraging flights. Moreover, correct landings at a dual-choice device after replacing the storing combs suggests that long-term memories formed within the colony can be retrieved while bees search for food in the field.

  10. SILAGE QUALITY OF CORN AND SORGHUM ADDED WITH FORAGE PEANUTS

    Directory of Open Access Journals (Sweden)

    WALKÍRIA GUIMARÃES CARVALHO

    2016-01-01

    Full Text Available Corn and sorghum are standard silage crops because of their fermentative characteristics. While corn and sorghum silages have lower crude protein (CP contents than other crops, intercropping with legumes can increase CP content. Furthermore, one way to increase CP content is the addition of legumes to silage. Consequently, the research objective was to evaluate the fermentative and bromatological characteristics of corn (Zea mays and sorghum (Sorghum bicolor silages added with forage peanuts (Arachis pintoi. The experimental design was completely randomized with four replicates. The treatments consisted of corn silage, sorghum silage, forage peanut silage, corn silage with 30% forage peanut, and sorghum silage with 30% forage peanut. The results showed that the corn and sorghum added with peanut helped to improve the silage fermentative and bromatological characteristics, proving to be an efficient technique for silage quality. The forage peanut silage had lower fermentative characteristics than the corn and sorghum silages. However, the forage peanut silage had a greater CP content, which increased the protein contents of the corn and sorghum silages when intercropped with forage peanuts.

  11. 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

    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...

  12. 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.

  13. 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.

  14. 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.

  15. The influence of reproductive condition and concurrent environmental factors on torpor and foraging patterns in female big brown bats (Eptesicus fuscus).

    Science.gov (United States)

    Rintoul, Jody L P; Brigham, R Mark

    2014-08-01

    Unlike many other mammals, bats in temperate regions employ short bouts of torpor throughout the reproductive period to maintain a positive energy balance. In addition to decreasing energy expenditure during the day, they typically alter foraging patterns as well. It is well known that various environmental conditions influence both torpor and foraging patterns, but studies of these factors often have focussed on one element in isolation thus it is not known how the two behaviours are collectively influencing temperate bats. The objective of our study was to assess how reproductive condition and environmental factors concurrently affect energy balance in female big brown bats (Eptesicus fuscus). We equipped pregnant and lactating bats in southwest Saskatchewan, Canada with temperature-sensitive radio-transmitters. While transmitters were active, skin temperature data were collected and foraging patterns were determined using triangulation. Of the various environmental and physiological parameters used to model torpor characteristics, roost type was the most important factor. Bats roosting in trees used deeper and longer torpor bouts than those roosting in buildings. Lactating bats had a tendency to forage for longer durations than pregnant bats, and often made more foraging trips. When taken together, we found that foraging duration and torpor duration were not directly related during pregnancy, but exhibited an inverse relationship during lactation. This provides support for the hypothesis that there are physiological trade-offs for reproductive bats and suggests that how bats compensate is not entirely predictable based on current environmental conditions.

  16. Effect of cutting intervals and heights in forage productivity of Moringa oleifera.

    Directory of Open Access Journals (Sweden)

    Ramos-Trejo O.

    2015-07-01

    Full Text Available The use of Moringa oleifera as fodder is due to its good nutritional characteristics and high yield of fresh biomass. Eastern Yucatan, Mexico has favorable soil and climatic conditions for its establishment. The aim of this work was to estimate forage productivity of Moringa oleifera in two cutting intervals and three different heights. The experiment was conducted at the Experimental Site of Tizimín fron the National Institute of Forest, Agricultural and lLvestock Researches (INIFAP. The experimental units were placed in a completely randomized design with a 2 x 3 factorial arrangement and four replications. Forage yield was quantified and foliage samples were taken for DM content. Significant differences (p0.05 were found. In conclusion, during the evaluation of Moringa oleifera, it was found that the best performance in this work is obtained when the cuts on the soles are made every 60 days at a height of 40 cm (1.9119 t ha-1 cut-1; however, more agronomic studies of this plant are recommended in the eastern Yucatan, such as: planting density, arrangement, partnerships with other shrub species in the region, rain and dry periods, in order to have a viable and profitable option forage productivity of this plant.

  17. Dry season forages for improving dairy production in smallholder systems in Uganda

    Directory of Open Access Journals (Sweden)

    Jolly Kabirizi

    2013-12-01

    Full Text Available Economically feasible strategies for year-round feed supply to dairy cattle are needed to improve feed resource availability, milk yield and household income for the smallholder dairy farming systems that predominate in the rural Eastern and Central African region. Currently, Napier grass (Pennisetum purpureum is the major forage in zero-grazing production systems, but dry-season production is often constrained. Our results from 24 farms show that sowing forage legumes, including Centrosema molle (formerly C. pubescens and Clitoria ternatea, with Napier grass and Brachiaria hybrid cv. Mulato improved both yield of forage and protein concentration. Sowing of 0.5 ha Napier-Centro plus 0.5 ha of Mulato-Clitoria increased milk yield by 80% and household income by 52% over 0.5 ha Napier grass monoculture. Possible income foregone from the crops which could have been grown on the additional 0.5 ha must be considered in assessing the economic viability of the system.

  18. 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

  19. Forage Production Technology Transfer in Kwale and Kilifi Districts of Coast Province

    International Nuclear Information System (INIS)

    Mwatate, C.D; Ramadhan, C.D.A; Njunie, M.N

    1999-01-01

    A forage production and utilisation programme was introduced in Kwale (AEZ CL2/CL3) and Kilifi (AEZ CL3/CL4) districts to combat major constraint in low quality and quantity feed at the coast. Dairy production had a great market potential stimulated by the high urban and rural population. Willing farmers were invited to PRC-Mtwapa to see how grasses, legumes and multipurpose trees would fit in their mixed maize cassava farming system. After explaining the forage characteristics to the farmers, they were allowed to select a maximum of three out of eight legumes (Vigna Unguiculata; Dolichos lablab; Clitoria tanatea; Stylosanthes guianennsis; Mucuna pruriens; Pueraria phaseloids; Macroptlium atropurpureum and Centrosema pubescens), tree out of five Napier grasses (Cultivar Mott, Clone 13, French Cameroon, Gold Coast and Bana). Giant panicum and and one of the two multipurpose trees (Gliricidia sepium and Leucaena leucocephala) to test in their farms. After planting in mid 1996 on-farm the research-extension team monitored ground cover and labor aplied monthly by gender, green leaf production, and survival over the drought in 1997. Along-side the planted forages, actual forage fed by dairy farmers was sampled, analysed for chemical composition and degradability to advise farmers on ration formulation. Ranking by farmers showed a preference for clitiria, Macuna and Dolichos in Kwale as the three best legumes. More than 70% of Napier grass variety had established while establishment rate of gliricidia was 33%. An extension leaflet developed during the study will be used to disseminate the information in the region

  20. 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.

  1. DYNAPHORE, INC., FORAGER SPONGE TECHNOLOGY - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    Science.gov (United States)

    The Forager Sponge is a volume reduction technology in which heavy metal contaminants from an aqueous medium are selectively concentrated into a smaller volume for facilitated disposal. he technology treats contaminated groundwater, surface voters and porous waters by absorbing d...

  2. SITE TECHNOLOGY CAPSULE: DYNAPHORE, INC., FORAGER SPONGE TECHNOLOGY

    Science.gov (United States)

    The Forager Sponge is a volume reduction technology in which heavy metal contaminants from an aqueous medium are selectively concentrated into a smaller volume for facilitated disposal. he technology treats contaminated groundwater, surface waters and porous waters by absorbing d...

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

    African Journals Online (AJOL)

    Mo

    documented on forage legumes and fodder trees in Uganda. However .... held to encourage interaction and collaborative learning between .... decision-making regarding income. ... the introduction of a milk-processing machine by Masaka.

  4. N-Nitroso Compound Precursors in some Nigerian Forage Crops ...

    African Journals Online (AJOL)

    N-Nitroso Compound Precursors in some Nigerian Forage Crops. ... were analyzed as their sulphonamides by gas chromatography interfaced with a chemiluminescence detector-Thermal Energy Analyzer modified for use in nitrogen mode.

  5. Foraging for brain stimulation: toward a neurobiology of computation.

    Science.gov (United States)

    Gallistel, C R

    1994-01-01

    The self-stimulating rat performs foraging tasks mediated by simple computations that use interreward intervals and subjective reward magnitudes to determine stay durations. This is a simplified preparation in which to study the neurobiology of the elementary computational operations that make cognition possible, because the neural signal specifying the value of a computationally relevant variable is produced by direct electrical stimulation of a neural pathway. Newly developed measurement methods yield functions relating the subjective reward magnitude to the parameters of the neural signal. These measurements also show that the decision process that governs foraging behavior divides the subjective reward magnitude by the most recent interreward interval to determine the preferability of an option (a foraging patch). The decision process sets the parameters that determine stay durations (durations of visits to foraging patches) so that the ratios of the stay durations match the ratios of the preferabilities.

  6. Physiology, phenology and behavioural strategies of forage fish

    DEFF Research Database (Denmark)

    Frisk, Christina

    Forage fish are small individuals, and are very abundant in numbers and can form dense schools. Forage fish are important within the food webs of the oceans, as they are at the lower trophic levels. Forage fish prey on zooplankton and they are themselves preyed on by piscivore fish. The individual...... forage fish and its growth dynamics are governed by an interplay between physiological rates, e.g. metabolism and consumption and the ambient environment as the rates are temperature dependent. The topic of this thesis is to describe the strong link between the individual and the environment through....... The model includes an additional structure pool; gonads, to which energy is transferred during the spawning season. During periods of poor feeding, energy to cover metabolic costs are firstly taken from the reserve pool and secondly, if the reserves are depleted, from the somatic tissue pool. The model...

  7. Emergence and seedling growth of five forage legume species at ...

    African Journals Online (AJOL)

    Jane

    2011-08-17

    Aug 17, 2011 ... A field study compared the seedling emergence and structure of five forage legumes .... mean seed mass (without seed coat) per species was used for W1 ...... Of light and length: regulation of hypocotyl growth in Arabidopsis.

  8. African Journal of Range and Forage Science - Vol 17 (2000)

    African Journals Online (AJOL)

    African Journal of Range and Forage Science. ... Estimation of the herbaceous standing crop of the grassy plains of 01 Choro Oiroua in the Masai ... truthing method for determination of rangeland biomass using canopy reflectance properties.

  9. A Novel Plant Root Foraging Algorithm for Image Segmentation Problems

    Directory of Open Access Journals (Sweden)

    Lianbo Ma

    2014-01-01

    Full Text Available This paper presents a new type of biologically-inspired global optimization methodology for image segmentation based on plant root foraging behavior, namely, artificial root foraging algorithm (ARFO. The essential motive of ARFO is to imitate the significant characteristics of plant root foraging behavior including branching, regrowing, and tropisms for constructing a heuristic algorithm for multidimensional and multimodal problems. A mathematical model is firstly designed to abstract various plant root foraging patterns. Then, the basic process of ARFO algorithm derived in the model is described in details. When tested against ten benchmark functions, ARFO shows the superiority to other state-of-the-art algorithms on several benchmark functions. Further, we employed the ARFO algorithm to deal with multilevel threshold image segmentation problem. Experimental results of the new algorithm on a variety of images demonstrated the suitability of the proposed method for solving such problem.

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

    Science.gov (United States)

    Scalise Sugiyama, Michelle

    2011-01-01

    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.

  11. 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...... 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...

  12. Foraging ecology and habitat association of black-winged lovebird ...

    African Journals Online (AJOL)

    26.4% of the lovebirds in Bole Sub-City were observed foraging on Zea mays and 16.5 % on Ricinus communis while in Entoto Natural Park, 50% of these lovebirds used the berries of Juniperus procera. Among the identified foraging plant parts, fruit had 60% in Bole Sub-City and 66.6% in Entoto Natural Park. The threat ...

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. Information Foraging in Nuclear Power Plant Control Rooms

    International Nuclear Information System (INIS)

    Boring, R.L.

    2011-01-01

    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.

  18. Visual field shape and foraging ecology in diurnal raptors.

    Science.gov (United States)

    Potier, Simon; Duriez, Olivier; Cunningham, Gregory B; Bonhomme, Vincent; O'Rourke, Colleen; Fernández-Juricic, Esteban; Bonadonna, Francesco

    2018-05-18

    Birds, particularly raptors, are believed to forage primarily using visual cues. However, raptor foraging tactics are highly diverse - from chasing mobile prey to scavenging - which may reflect adaptations of their visual systems. To investigate this, we studied the visual field configuration of 15 species of diurnal Accipitriformes that differ in such tactics, first focusing on the binocular field and blind area by using a single traits approach, and then exploring the shape of the binocular field with morphometric approaches. While the maximum binocular field width did not differ in species of different foraging tactics, the overall shape of their binocular fields did. In particular, raptors chasing terrestrial prey (ground predators) had a more protruding binocular field and a wider blind area above the head than did raptors chasing aerial or aquatic prey and obligate scavengers. Ground predators that forage on mammals from above have a wide but short bill - which increases ingestion rate - and large suborbital ridge to avoid sun glare. This may explain the protruding binocular field and the wide blind area above the head. By contrast, species from the two other groups have long but narrow bills used to pluck, flake or tear food and may need large visual coverage (and reduced suborbital ridges) to increase their foraging efficiency ( e.g. using large visual coverage to follow the escaping prey in three dimensions or detect conspecifics). We propose that binocular field shape is associated with bill and suborbital ridge shape and, ultimately, foraging strategies. © 2018. Published by The Company of Biologists Ltd.

  19. 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.

  20. Eye structure and amphibious foraging in albatrosses

    Science.gov (United States)

    Martin, G. R.

    1998-01-01

    Anterior eye structure and retinal visual fields were determined in grey-headed and black-browed albatrosses, Diomedea melanophris and D. chrysostoma (Procellariiformes, Diomedeidae), using keratometry and an ophthalmoscopic reflex technique. Results for the two species were very similar and indicate that the eyes are of an amphibious optical design suggesting that albatross vision is well suited to the visual pursuit of active prey both on and below the ocean surface. The corneas are relatively flat (radius ca. 14.5 mm) and hence of low absolute refractive power (ca. 23 dioptres). In air the binocular fields are relatively long (vertical extent ca. 70 degrees) and narrow (maximum width in the plane of the optic axes 26–32 degrees), a topography found in a range of bird species that employ visual guidance of bill position when foraging. The cyclopean fields measure approximately 270 degrees in the horizontal plane, but there is a 60 degrees blind sector above the head owing to the positioning of the eyes below the protruding supraorbital ridges. Upon immersion the monocular fields decrease in width such that the binocular fields are abolished. Anterior eye structure, and visual field topography in both air and water, show marked similarity with those of the Humboldt penguin.

  1. 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.

  2. 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.

  3. Simultaneous brightness contrast of foraging Papilio butterflies

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-01-01

    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. PMID:22179808

  4. A New Perspective on the Foraging Ecology of Apex Predators in the California Current: Results from a Fully Coupled Ecosystem Model

    Science.gov (United States)

    Fiechter, J.; Huckstadt, L. A.; Rose, K.; Costa, D. P.; Curchitser, E. N.; Hedstrom, K.; Edwards, C. A.; Moore, A. M.

    2016-02-01

    Results from a fully coupled end-to-end ecosystem model for the California Current Large Marine Ecosystem are used to describe the impact of environmental variability on the foraging ecology of its most abundant apex predator, California sea lions (Zalophus californianus). The ecosystem model consists of a biogeochemical submodel embedded in a regional ocean circulation submodel, and both coupled with a multi-species individual-based submodel for forage fish (sardine and anchovy) and California sea lions. For sea lions, bioenergetics and behavioral attributes are specified using available TOPP (Tagging Of Pacific Predators) data on their foraging patterns and diet in the California Current. Sardine and anchovy are explicitly included in the model as they represent important prey sources for California sea lions and exhibit significant interannual and decadal variability in population abundances. Output from a 20-year run (1989-2008) of the model demonstrates how different physical and biological processes control habitat utilization and foraging success of California sea lions on interannual time scales. A principal component analysis of sea lion foraging patterns indicates that the first mode of variability is alongshore and tied to sardine availability, while the second mode is cross-shore and associated with coastal upwelling intensity (a behavior consistent with male sea lion tracking data collected in 2004 vs. 2005). The results also illustrate how variability in environmental conditions and forage fish distribution affects sea lions feeding success. While specifically focusing on the foraging ecology of sea lions, our modeling framework has the ability to provide new and unique perspectives on trophic interactions in the California Current, or other regions where similar end-to-end ecosystem models may be implemented.

  5. 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. Copyright © 2015 Cognitive Science Society, Inc.

  6. 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.

  7. Subjective costs drive overly patient foraging strategies in rats on an intertemporal foraging task.

    Science.gov (United States)

    Wikenheiser, Andrew M; Stephens, David W; Redish, A David

    2013-05-14

    Laboratory studies of decision making often take the form of two-alternative, forced-choice paradigms. In natural settings, however, many decision problems arise as stay/go choices. We designed a foraging task to test intertemporal decision making in rats via stay/go decisions. Subjects did not follow the rate-maximizing strategy of choosing only food items associated with short delays. Instead, rats were often willing to wait for surprisingly long periods, and consequently earned a lower rate of food intake than they might have by ignoring long-delay options. We tested whether foraging theory or delay discounting models predicted the behavior we observed but found that these models could not account for the strategies subjects selected. Subjects' behavior was well accounted for by a model that incorporated a cost for rejecting potential food items. Interestingly, subjects' cost sensitivity was proportional to environmental richness. These findings are at odds with traditional normative accounts of decision making but are consistent with retrospective considerations having a deleterious influence on decisions (as in the "sunk-cost" effect). More broadly, these findings highlight the utility of complementing existing assays of decision making with tasks that mimic more natural decision topologies.

  8. Subalpine bumble bee foraging distances and densities in relation to flower availability.

    Science.gov (United States)

    Elliott, Susan E

    2009-06-01

    Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations, especially in high elevation areas. Foraging distances and relationships between forager densities and resource availability can provide insights into the potential for food limitation in mobile consumer populations. For example, if floral resources are limited, bee consumers should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated subalpine bumble bee foraging distances by calculating forager recapture probabilities at increasing distances from eight marking locations. I measured forager and flower densities over the flowering season in six half-hectare plots. Because subalpine bumble bees have little time to build their colonies, they may forage over short distances and forager density may not be constrained by flower density. However, late in the season, when floral resources dwindle, foraging distances may increase, and there may be stronger relationships between forager and flower densities. Throughout the flowering season, marked bees were primarily found within 100 m (and never >1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foraging queens increased with early-season flower density, the density of mid- and late-season workers and males did not vary with flower density. Short foraging distances and no relationships between mid- and late-season forager and flower densities suggest that high elevation bumble bees may have ample floral resources for colony growth reproduction.

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

    Directory of Open Access Journals (Sweden)

    Marianna Chimienti

    2014-09-01

    Full Text Available 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

  10. Evidence for foraging -site fidelity and individual foraging behavior of pelagic cormorants rearing chicks in the gulf of Alaska

    Science.gov (United States)

    Kotzerka, J.; Hatch, Shyla A.; Garthe, S.

    2011-01-01

    The Pelagic Cormorant (Phalacrocorax pelagicus) is the most widespread cormorant in the North Pacific, but little is known about its foraging and diving behavior. However, knowledge of seabirds' foraging behavior is important to understanding their function in the marine environment. In 2006, using GPS dataloggers, we studied the foraging behavior of 14 male Pelagic Cormorants rearing chicks on Middleton Island, Alaska. For foraging, the birds had high fidelity to a small area 8 km north of the colony. Within that area, the cormorants' diving activity was of two distinct kinds-near-surface dives (1-6 m) and benthic dives (28-33 m). Individuals were consistent in the depths of their dives, either mostly shallow or mostly deep. Few showed no depth preference. Dive duration, time at maximum depth, and pauses at the water surface between consecutive dives were shorter for shallow dives than for deep dives. The cormorants made dives of both types throughout the day, but the frequency of deep dives increased toward evening. Maximum foraging range was 9 km; maximum total distance traveled per trip was 43.4 km. Trip durations ranged from 0.3 to 7.7 hr. Maximum depth of a dive was 42.2 m, and duration of dives ranged from 4 to 120 sec. We found that Pelagic Cormorants at Middleton Island were faithful to one particular foraging area and individuals dived in distinct patterns. Distinct, specialized foraging behavior may be advantageous in reducing intra- and interspecific competition but may also render the species vulnerable to changing environmental conditions. Copyright ?? The Cooper Ornithological Society 2011.

  11. Foraging in corallivorous butterflyfish varies with wave exposure

    Science.gov (United States)

    Noble, Mae M.; Pratchett, Morgan S.; Coker, Darren J.; Cvitanovic, Christopher; Fulton, Christopher J.

    2014-06-01

    Understanding the foraging patterns of reef fishes is crucial for determining patterns of resource use and the sensitivity of species to environmental change. While changes in prey availability and interspecific competition have been linked to patterns of prey selection, body condition, and survival in coral reef fishes, rarely has the influence of abiotic environmental conditions on foraging been considered. We used underwater digital video to explore how prey availability and wave exposure influence the behavioural time budgets and prey selectivity of four species of obligate coral-feeding butterflyfishes. All four species displayed high selectivity towards live hard corals, both in terms of time invested and frequency of searching and feeding events. However, our novel analysis revealed that such selectivity was sensitive to wave exposure in some species, despite there being no significant differences in the availability of each prey category across exposures. In most cases, these obligate corallivores increased their selectivity towards their most favoured prey types at sites of high wave exposure. This suggests there are costs to foraging under different wave environments that can shape the foraging patterns of butterflyfishes in concert with other conditions such as prey availability, interspecific competition, and territoriality. Given that energy acquisition is crucial to the survival and fitness of fishes, we highlight how such environmental forcing of foraging behaviour may influence the ecological response of species to the ubiquitous and highly variable wave climates of shallow coral reefs.

  12. Corticosterone predicts foraging behavior and parental care in macaroni penguins.

    Science.gov (United States)

    Crossin, Glenn T; Trathan, Phil N; Phillips, Richard A; Gorman, Kristen B; Dawson, Alistair; Sakamoto, Kentaro Q; Williams, Tony D

    2012-07-01

    Corticosterone has received considerable attention as the principal hormonal mediator of allostasis or physiological stress in wild animals. More recently, it has also been implicated in the regulation of parental care in breeding birds, particularly with respect to individual variation in foraging behavior and provisioning effort. There is also evidence that prolactin can work either inversely or additively with corticosterone to achieve this. Here we test the hypothesis that endogenous corticosterone plays a key physiological role in the control of foraging behavior and parental care, using a combination of exogenous corticosterone treatment, time-depth telemetry, and physiological sampling of female macaroni penguins (Eudyptes chrysolophus) during the brood-guard period of chick rearing, while simultaneously monitoring patterns of prolactin secretion. Plasma corticosterone levels were significantly higher in females given exogenous implants relative to those receiving sham implants. Increased corticosterone levels were associated with significantly higher levels of foraging and diving activity and greater mass gain in implanted females. Elevated plasma corticosterone was also associated with an apparent fitness benefit in the form of increased chick mass. Plasma prolactin levels did not correlate with corticosterone levels at any time, nor was prolactin correlated with any measure of foraging behavior or parental care. Our results provide support for the corticosterone-adaptation hypothesis, which predicts that higher corticosterone levels support increased foraging activity and parental effort.

  13. 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

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

    Science.gov (United States)

    Threlfall, Caragh G; Law, Bradley; Banks, Peter B

    2012-01-01

    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 plandscapes. 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 foraging habitats.

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

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    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.

  16. 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.

  17. Vision and touch in relation to foraging and predator detection : insightful contrasts between a plover and a sandpiper

    NARCIS (Netherlands)

    Martin, Graham R.; Piersma, Theunis

    2009-01-01

    Visual fields were determined in two species of shorebirds (Charadriiformes) whose foraging is guided primarily by different sources of information: red knots (Calidris canutus, tactile foragers) and European golden plovers (Pluvialis apricaria, visual foragers). The visual fields of both species

  18. 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...... 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...... the animals’ ability to forage efficiently and to sustain their energy intake, is influenced by noise emitted from wind turbines and ships. The energy levels in turn affect their survival. The fine-scale movements of the simulated animals was governed by a spatial memory, which allowed the model to produce...

  19. 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

  20. Optimal foraging in marine ecosystem models: selectivity, profitability and switching

    DEFF Research Database (Denmark)

    Visser, Andre W.; Fiksen, Ø.

    2013-01-01

    ecological mechanics and evolutionary logic as a solution to diet selection in ecosystem models. When a predator can consume a range of prey items it has to choose which foraging mode to use, which prey to ignore and which ones to pursue, and animals are known to be particularly skilled in adapting...... to the preference functions commonly used in models today. Indeed, depending on prey class resolution, optimal foraging can yield feeding rates that are considerably different from the ‘switching functions’ often applied in marine ecosystem models. Dietary inclusion is dictated by two optimality choices: 1...... by letting predators maximize energy intake or more properly, some measure of fitness where predation risk and cost are also included. An optimal foraging or fitness maximizing approach will give marine ecosystem models a sound principle to determine trophic interactions...

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

    Science.gov (United States)

    Boyette, Adam H

    2016-05-01

    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 the contexts of most play research. Analysis of systematic observations of children's play among Aka forest foragers (n = 50, ages 4-16, M = 9.5) and Ngandu subsistence farmers (n = 48, ages 4-16, M = 9.1) collected in 2010 illustrates that while play and work trade off during development in both groups, and consistent patterns in sex-role development are evident, Aka children engage in significantly less rough-and-tumble play and competitive games than children among their socially stratified farming neighbors. © 2016 The Authors. Child Development © 2016 Society for Research in Child Development, Inc.

  2. Evaluation some Forage Legumes in Limited Irrigation Condition

    Directory of Open Access Journals (Sweden)

    Hassan Moniri Far

    2015-11-01

    Full Text Available Forage legumes respond differently to limited irrigation regimes. Their evaluation may, thus, help to select drought tolerant types for limited irrigation conditions. In this study four type of forage legume were studied for two years in Tikma-Dash Research Station of East Azarbaijan Agricultural and Natural Research Center, Tabriz, Iran, in a randomized complete block design using split-plot experiment in 2011-2013 years. Irrigation regimes (without irrigation, one irrigation and two irrigations were assigned to main plots and four forage types (hairy vetch, grass pea, Pannonica sativa and lathyrus were assigned to subplots. The results of analysis of variance showed that the effect of irrigation on plant height, number of shoots, leaf area and plant fresh and dry weights were not significant. Howere, legume types affected these traits significantly (P≤0.01. The effect of irrigation levels and legume types on protein content of hay were significant (P

  3. The Müller-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.

  4. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. 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

  6. 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. (c) 2009 Wiley-Liss, Inc.

  7. 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 fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

  8. Physiological effects of increased foraging effort in a small passerine.

    Science.gov (United States)

    Yap, Kang Nian; Kim, Oh Run; Harris, Karilyn C; Williams, Tony D

    2017-11-15

    Foraging to obtain food, either for self-maintenance or at presumably elevated rates to provide for offspring, is thought to be an energetically demanding activity but one that is essential for fitness (higher reproductive success and survival). Nevertheless, the physiological mechanisms that allow some individuals to support higher foraging performance, and the mechanisms underlying costs of high workload, remain poorly understood. We experimentally manipulated foraging behaviour in zebra finches ( Taeniopygia guttata ) using the technique described by Koetsier and Verhulst (2011) Birds in the 'high foraging effort' (HF) group had to obtain food either while flying/hovering or by making repeated hops or jumps from the ground up to the feeder, behaviour typical of the extremely energetically expensive foraging mode observed in many free-living small passerines. HF birds made significantly more trips to the feeder per 10 min, whereas control birds spent more time (perched) at the feeder. Despite this marked change in foraging behaviour, we documented few short- or long-term effects of 'training' (3 days and 90 days of 'training', respectively) and some of these effects were sex specific. There were no effects of treatment on basal metabolic rate, haematocrit, haemoglobin or plasma glycerol, triglyceride and glucose levels, and masses of kidney, crop, large intestine, small intestine, gizzard and liver. HF females had higher masses of flight muscle, leg muscle, heart and lung compared with controls. In contrast, HF males had lower heart mass than controls and there were no differences for other organs. When both sexes were pooled, there were no effects of treatment on body composition. Finally, birds in the HF treatment group had higher levels of reactive oxygen metabolites (dROMs) and, consequently, although treatment did not affect total anti-oxidant capacity, birds in the HF treatment group had higher oxidative stress. © 2017. Published by The Company of

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

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    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.

  10. The Occurrence, Biosynthesis, and Molecular Structure of Proanthocyanidins and Their Effects on Legume Forage Protein Precipitation, Digestion and Absorption in the Ruminant Digestive Tract

    Directory of Open Access Journals (Sweden)

    Arjan Jonker

    2017-05-01

    Full Text Available Forages grown in temperate regions, such as alfalfa (Medicago sativa L. and white clover (Trefolium repens L., typically have a high nutritional value when fed to ruminants. Their high protein content and degradation rate result, however, in poor utilization of protein from the forage resulting in excessive excretion of nitrogen into the environment by the animal. Proanthocyanindins (also known as condensed tannins found in some forage legumes such as birdsfoot trefoil (Lotus corniculatus L., bind to dietary protein and can improve protein utilization in the animal. This review will focus on (1 the occurrence of proanthocyanidins; (2 biosynthesis and structure of proanthocyanidins; (3 effects of proanthocyanidins on protein metabolism; (4 protein precipitating capacity of proanthocyanidins and their effects on true intestinal protein adsorption by ruminants; and (5 effect on animal health, animal performance and environmental emissions.

  11. A molecular phylogeny of Dorylus army ants provides evidence for multiple evolutionary transitions in foraging niche

    DEFF Research Database (Denmark)

    Kronauer, Daniel J C; Schöning, Caspar; Vilhelmsen, Lars

    2007-01-01

    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......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...

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

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    Katsunori Sunagawa

    2016-02-01

    Full Text Available 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

  13. Foraging strategies of the Galapagos Marine Iguana (Amblyrhynchus Cristatus): adapting behavioral rules to ontogenetic size change

    OpenAIRE

    Wikelski, Martin; Trillmich, Fritz

    1994-01-01

    Ontogenetic development in reptiles entails major changes in size-related foraging options. We studied the changes in foraging behavior of marine iguanas. In this species, size increases about twenty- to hundredfold from hatching to full adult size. The foraging strategy of marine iguanas was studied at Miedo on Santa Fe Island in the Galapagos archipelago During low tide, large marine iguanas (>250 mm snout vent length (SVL)) foraged more in the lower intertidal than small ones (

  14. Does foraging behaviour affect female mate preferences and pair formation in captive zebra finches?

    Directory of Open Access Journals (Sweden)

    Neeltje J Boogert

    Full Text Available BACKGROUND: Successful foraging is essential for survival and reproductive success. In many bird species, foraging is a learned behaviour. To cope with environmental change and survive periods in which regular foods are scarce, the ability to solve novel foraging problems by learning new foraging techniques can be crucial. Although females have been shown to prefer more efficient foragers, the effect of males' foraging techniques on female mate choice has never been studied. We tested whether females would prefer males showing the same learned foraging technique as they had been exposed to as juveniles, or whether females would prefer males that showed a complementary foraging technique. METHODOLOGY/PRINCIPAL FINDINGS: We first trained juvenile male and female zebra finches (Taeniopygia guttata to obtain a significant proportion of their food by one of two foraging techniques. We then tested whether females showed a preference for males with the same or the alternative technique. We found that neither a male's foraging technique nor his foraging performance affected the time females spent in his proximity in the mate-choice apparatus. We then released flocks of these finches into an aviary to investigate whether assortative pairing would be facilitated by birds taught the same technique exploiting the same habitat. Zebra finches trained as juveniles in a specific foraging technique maintained their foraging specialisation in the aviary as adults. However, pair formation and nest location were random with regard to foraging technique. CONCLUSIONS/SIGNIFICANCE: Our findings show that zebra finches can be successfully trained to be foraging specialists. However, the robust negative results of the conditions tested here suggest that learned foraging specializations do not affect mate choice or pair formation in our experimental context.

  15. Invited review: Sustainable forage and grain crop production for the US dairy industry.

    Science.gov (United States)

    Martin, N P; Russelle, M P; Powell, J M; Sniffen, C J; Smith, S I; Tricarico, J M; Grant, R J

    2017-12-01

    A resilient US dairy industry will be underpinned by forage and crop production systems that are economically, environmentally, and socially sustainable. Land use for production of perennial and annual forages and grains for dairy cattle must evolve in response to multiple food security and environmental sustainability issues. These include increasing global populations; higher incomes and demand for dairy and other animal products; climate change with associated temperature and moisture changes; necessary reductions in carbon and water footprints; maintenance of soil quality and soil nutrient concerns; and competition for land. Likewise, maintaining producer profitability and utilizing practices accepted by consumers and society generally must also be considered. Predicted changes in climate and water availability will likely challenge current feed and dairy production systems and their national spatial distribution, particularly the western migration of dairy production in the late 20th century. To maintain and stabilize profitability while reducing carbon footprint, particularly reductions in methane emission and enhancements in soil carbon sequestration, dairy production will need to capitalize on genetic and management innovations that enhance forage and grain production and nutritive value. Improved regional and on-farm integration of feed production and manure utilization is needed to reduce environmental nitrogen and phosphorus losses and mitigate greenhouse gas emissions. Resilient and flexible feed production strategies are needed to address each of these challenges and opportunities to ensure profitable feeding of dairy cattle and a sustainable dairy industry. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  16. Nutrient balance affects foraging behaviour of a trap-building predator

    DEFF Research Database (Denmark)

    Mayntz, David; Toft, Søren; Vollrath, Fritz

    2009-01-01

    Predator foraging may be affected by previous prey capture, but it is unknown how nutrient balance affects foraging behaviour. Here, we use a trap-building predator to test whether nutrients from previous prey captures affect foraging behaviour. We fed orb-weaving spiders (Zygiella x-notata) prey...

  17. 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...

  18. Systematic review of the influence of foraging habitat on red-cockaded woodpecker reproductive success

    Science.gov (United States)

    James E. Garabedian; Christopher E. Moorman; M. Nils Peterson; John C. Kilgo

    2014-01-01

    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...

  19. Effects of foraging mode and season on the energetics of the Marine Iguana, Amblyrhynchus cristatus

    NARCIS (Netherlands)

    Drent, J; Lichtenbelt, WDV; Wikelski, M

    1, Marine Iguanas (Amblyrhynchus cristatus) inhabiting the rocky shores of the Galapagos Islands apply two foraging strategies, intertidal and subtidal foraging, in a seasonal climate. Effects of both foraging strategy and seasonality on the daily energy expenditure (DEE) were measured using doubly

  20. Neutron activation analysis of zinc in forages used in intensive dairy cattle production systems

    International Nuclear Information System (INIS)

    Armelin, M.J.A.; Piasentin, R.M.; Primavesi, O.

    2002-01-01

    Instrumental neutron activation analysis (INAA) was applied for the determination of Zn concentration in the main tropical grass forages used in intensive dairy cattle production systems, in Brazil. Smaller Zn concentration could be verified in the rainy period. Comparison of results obtained in these analyses of forages dry matter with daily requirements pointed towards deficiency of Zn in the forages. (author)

  1. Application of a rising plate meter to estimate forage yield on dairy farms in Pennsylvania

    Science.gov (United States)

    Accurately assessing pasture forage yield is necessary for producers who want to budget feed expenses and make informed pasture management decisions. Clipping and weighing forage from a known area is a direct method to measure pasture forage yield, however it is time consuming. The rising plate mete...

  2. 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...

  3. Variation in predator foraging behavior changes predator-prey spatio-temporal dynamics

    Science.gov (United States)

    1. Foraging underlies the ability of all animals to acquire essential resources and, thus, provides a critical link to understanding population dynamics. A key issue is how variation in foraging behavior affects foraging efficiency and predator-prey interactions in spatially-heterogeneous environmen...

  4. Whose urban forest? The political ecology of foraging urban nontimber forest products

    Science.gov (United States)

    Patrick T. Hurley; Marla R. Emery; Rebecca McLain; Melissa Poe; Brian Grabbatin; Cari L. Goetcheus

    2015-01-01

    Drawing on case studies of foraging in Philadelphia, Pennsylvania and Mt. Pleasant, South Carolina, we point to foraging landscapes and practices within diverse urban forest spaces. We examine these spaces in relation to U.S. conservation and development processes and the effects of management and governance on species valued by foragers. These case studies reveal the...

  5. Foraging at wastewater treatment works increases the potential for ...

    African Journals Online (AJOL)

    Wastewater treatment works (WWTWs) are known to provide profitable foraging areas for insectivorous bats in Europe and the New World because of their association with high abundance of pollution-tolerant midges (Diptera). However, bats that feed on these insects may also accumulate metal pollutants such as cadmium ...

  6. Comparison of nectar foraging efficiency in the Cape honeybee ...

    African Journals Online (AJOL)

    1987-03-17

    Mar 17, 1987 ... Comparison of nectar foraging efficiency in the Cape honeybee, Apis mellifera capensis Escholtz, and the African honeybee, Apis mellifera adansonii Latreille,. , in the western Cape Province. P.V. W-Worswick*. Department of Zoology, University of Cape Town, Rondebosch 7700 Republic of South Africa.

  7. 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.

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

    Science.gov (United States)

    Steven F. Railsback; Bret C. Harvey

    2013-01-01

    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...

  9. 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.

  10. Forage seeding in rangelands increases production and prevents weed invasion

    Directory of Open Access Journals (Sweden)

    Josh Davy

    2017-07-01

    Full Text Available Increasing forage productivity in the Sierra foothill rangelands would help sustain the livestock industry as land availability shrinks and lease rates rise, but hardly any studies have been done on forage selections. From 2009 to 2014, in one of the first long-term and replicated studies of seeding Northern California's Mediterranean annual rangeland, we compared the cover of 22 diverse forages to determine their establishment and survivability over time. Among the annual herbs, forage brassica (Brassica napus L. and chicory (Cichorium intybus L. proved viable options. Among the annual grasses, soft brome (Bromus hordeaceus and annual ryegrass (Lolium multiflorum performed well. However, these species will likely require frequent reseeding to maintain dominance. Long-term goals of sustained dominant cover (> 3 years are best achieved with perennial grasses. Perennial grasses that persisted with greater than 50% cover were Berber orchardgrass (Dactylis glomerata, Flecha tall fescue (Lolium arundinaceum and several varieties of hardinggrass (Phalaris aquatica L., Perla koleagrass, Holdfast, Advanced AT. In 2014, these successful perennials produced over three times more dry matter (pounds per acre than the unseeded control and also suppressed annual grasses and yellow starthistle (Centaurea solstitialis L. cover.

  11. 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

  12. Intensification of grassland and forage use: driving forces and constraints

    NARCIS (Netherlands)

    Oenema, O.; Klein, de C.; Alfaro, M.

    2014-01-01

    The increasing demand for safe and nutritional dairy and beef products in a globalising world, together with the needs to increase resource use efficiency and to protect biodiversity, provide strong incentives for intensification of grassland and forage use. This paper addresses the question: 'Does

  13. Optimal foraging and predator-prey dynamics III

    Czech Academy of Sciences Publication Activity Database

    Křivan, Vlastimil; Eisner, Jan

    2003-01-01

    Roč. 63, - (2003), s. 269-279 ISSN 0040-5809 R&D Projects: GA ČR GA201/03/0091; GA MŠk LA 101 Institutional research plan: CEZ:AV0Z5007907 Keywords : Optimal foraging theory * adaptive behavior * predator-prec population dynamics Subject RIV: EH - Ecology, Behaviour Impact factor: 2.261, year: 2003

  14. Forage Potential of Photoperiod-Sensitive millet ( Pennisetum ...

    African Journals Online (AJOL)

    To determine its potential as an annual forage, 'Maiwa', which is a short-day photoperiod-sensitive millet (Pennisetum americanum (Linn.) ... Improvement in the level and seasonal distribution of 'maiwa' herbage production as well as quality can be realised through suitable agronomic practices as well as breeding.

  15. 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…

  16. The impact of grazing on forage quality of the herbaceous ...

    African Journals Online (AJOL)

    Reports on research conducted in the Mamoro cork oak forest of Morocco to describe the impacts of sheep grazing in March, April, May and June of 1987 and 1988 on seasonal changes in forage quality of the herbaceous vegetation. The study showed that trends in herbage quality were related mainly to plant maturity.

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

    African Journals Online (AJOL)

    Foraging activity of Acanthochitona gamoti was studied during spring and neap tides in three different habitats: an aeolian sandstone ... mm) during a spring tide new moon and least on a spring tide full moon (x = 4.0 h; x = 182 rnm). Chitons on the boulder ..... BECKLEY, L.E. 1994. Two Oceans: A guide to Marine Life of.

  18. Foraging and pollination behaviour of the African Honey bee ( Apis ...

    African Journals Online (AJOL)

    Foraging and pollination behaviour of the African Honey bee (Apis mellifera adansonii) on Callistemon rigidus flowers in Ngaoundere (Cameroon). F-N Tchuenguem Fohouo, J Messi, D Brüchner, B Bouba, G Mbofung, J Hentchoya Hemo. Abstract. No Abstract Available Journal of the Cameroon Academy of Sciences ...

  19. Search paths of swans foraging on spatially autocorrelated tubers

    NARCIS (Netherlands)

    Nolet, B.A.; Mooij, W.M.

    2002-01-01

    1. Tundra swans forage on below-ground pondweed tubers that are heterogeneously distributed in space. The swans have no visual cues to delineate patches. It was tested whether swans employ an area-restricted search tactic. Theory predicts that swans should alternate between an intensive (low-speed,

  20. biomass production and forage quality of head-smut disease ...

    African Journals Online (AJOL)

    ACSS

    The objective of this study was to determine biomass yield and forage quality of head- smut resistant/tolerant Napier grass .... demands deployment of suitable Napier grass cultivars, with resistance/tolerance to drought conditions .... diets need to be balanced to contain sufficient and effective NDF for healthy rumen function,.

  1. Variability in foraging behaviour and prey of the Common Fiscal ...

    African Journals Online (AJOL)

    Aspects of the foraging behaviour along an altitudinal gradient of four subpopulations Durban, Merrivale, Estcourt and Harrismith) of colour-banded Common Fiscals (Lanius collaris) were analysed in summer and winter in South Africa. ... items can be taken with little opportunity cost while waiting for better items to appear.

  2. 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...

  3. Resource ecology : spatial and temporal dynamics of foraging

    NARCIS (Netherlands)

    Prins, H.H.T.; Langevelde, van F.

    2008-01-01

    This multi-author book deals with 'resource ecology', which is the ecology of trophic interactions between consumers and their resources. Resource ecology is perhaps the most central part of ecology. In its linkage between foraging theory and spatial ecology, it shows how old and fundamental

  4. development of oscillating classifiers for forage chop length ...

    African Journals Online (AJOL)

    Dr Obe

    1987-09-01

    Sep 1, 1987 ... 6.Calculation of Forage Chop Size. Particle size distribution is characterised by the parameters that measure the central tendency of the distribution and the dispersion about the central tendency. Most fine particle systems obey the logarithmic normal distribution function [4]. This means that the distribution.

  5. 7 CFR 457.151 - Forage seeding crop insurance provisions.

    Science.gov (United States)

    2010-01-01

    ..., as shown in the actuarial documents. Good farming practices—The cultural practices generally in use.... Replanting—Performing the cultural practices necessary to prepare the land for replacing of the forage seed... accordance with good farming practices on or before the late harvest date. (d) Final adjustment of a loss on...

  6. Costs associated with tail autotomy in an ambush foraging lizard ...

    African Journals Online (AJOL)

    We induced tail autotomy in free ranging male Cordylus m. melanotus and measured potential shifts in behaviour (movements, foraging behaviour, time exposed and average distance to a potential refuge), and responses to an approaching human compared to marked individuals with complete tails. Tailed and tailless ...

  7. Use of biosolids to enhance rangeland forage quality.

    Science.gov (United States)

    McFarland, Michael J; Vasquez, Issaak Romero; Vutran, MaiAnh; Schmitz, Mark; Brobst, Robert B

    2010-05-01

    Biosolids land application was demonstrated to be a potentially cost-effective means for restoring forage productivity and enhancing soil-moisture-holding capacity on disturbed rangelands. By land-applying aerobically digested, anaerobically digested, composted, and lime-stabilized biosolids on rangeland test plots at rates of up to 20 times (20X) the estimated nitrogen-based agronomic rate, forage yields were found to increase from 132.8 kg/ha (118.2 lb/ac) (control plots) to 1182.3 kg/ha (1052.8 lb/ac). Despite the environmental benefits associated with increased forage yield (e.g., reduced soil erosion, improved drainage, and enhanced terrestrial carbon sequestration), the type of forage generated both before and after biosolids land application was found to be dominated by invasive weeds, all of which were characterized as having fair to poor nutritional value. Opportunistic and shallow rooting invasive weeds not only have marginal nutritional value, they also limit the establishment of native perennial grasses and thus biodiversity. Many of the identified invasive species (e.g., Cheatgrass) mature early, a characteristic that significantly increases the fuel loads that support the increased frequency and extent of western wildfires.

  8. Short Communication: Effect of forage sources and Saccharomyces ...

    African Journals Online (AJOL)

    Diets based on lucerne hay (462 g/kg DM) and maize silage (488 g/kg DM) were fed to determine the effects of 0 or 5 g SC 47 (8´109 cfu/g) on ruminal digestion, fermentation and protozoa population. Ruminal pH, acetate, propionate, degradation rate and effective degradability were significantly affected by the forage ...

  9. 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.

  10. Effects of growth stage on quality characteristics of triticale forages

    Science.gov (United States)

    The use of triticale (X Triticosecale Wittmack) in dairy-cropping systems has expanded greatly in recent years, partly to improve land stewardship by providing winter ground cover. Our objectives were to relate the nutritive value of triticale forages grown in central Wisconsin with plant growth sta...

  11. Cyber Foraging for Improving Survivability of Mobile Systems

    Science.gov (United States)

    2016-02-10

    Cyber-Foraging for Improving Survivability of Mobile Systems Sebastián Echeverría ( Universidad de los Andes) Grace A. Lewis James Root Ben...NUMBERS FA8721-05-C-0003 6. AUTHOR(S) Sebastián Echeverría ( Universidad de los Andes), Grace A. Lewis, James Root, & Ben Bradshaw 7. PERFORMING

  12. Systematics, diversity and forage value of indigenous legumes of ...

    African Journals Online (AJOL)

    A map representing the collection intensity for the study area showed that the majority of legumes species were collected in the Fynbos, Savanna and Grassland Biome. It is concluded that indigenous South African legumes are extremely diverse and this denotes the importance of further investigating their forage potential ...

  13. Forage yield of berseem (Trifolium alaxandrium) as affected by ...

    African Journals Online (AJOL)

    Jane

    2011-10-17

    Oct 17, 2011 ... wheat straw is traditionally fed during winter and spring. *Corresponding author. E-mail: ijaz132@yahoo.co.uk. In irrigated areas of Pakistan where although green. fodder is a traditional crop, only a few local fodder species and varieties are in widespread use. The ability of the given forage species to ...

  14. Are great tits (Parus major) really optimal foragers?

    Czech Academy of Sciences Publication Activity Database

    Berec, Michal; Křivan, Vlastimil; Berec, Luděk

    2003-01-01

    Roč. 81, - (2003), s. 780-788 ISSN 0008-4301 R&D Projects: GA AV ČR IAA6007303 Institutional research plan: CEZ:AV0Z5007907; CEZ:MSM 123100004 Keywords : Optimal foraging theory * optimal prey selection Subject RIV: EG - Zoology Impact factor: 1.115, year: 2003

  15. Emergence of forage legume seedlings influenced by water ...

    African Journals Online (AJOL)

    Emergence of forage legume seedlings influenced by water potential and soil strength. DMG Njarui, LM Bahnisch, B O'Hagan, B So. Abstract. No Abstract Available E. Afr. Agric. For. J. 2003 69(1), 29-38. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

  16. Specialist Osmia bees forage indiscriminately among hybridizing Balsamorhiza floral hosts

    Science.gov (United States)

    James H. Cane

    2011-01-01

    Pollinators, even floral generalists (=polyleges), typically specialize during individual foraging bouts, infrequently switching between floral hosts. Such transient floral constancy restricts pollen flow, and thereby gene flow, to conspecific flowers in mixed plant communities. Where incipient flowering species meet, however, weak cross-fertility and often similar...

  17. 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...

  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. Linking mesopelagic prey abundance and distribution to the foraging behavior of a deep-diving predator, the northern elephant seal

    Science.gov (United States)

    Saijo, Daisuke; Mitani, Yoko; Abe, Takuzo; Sasaki, Hiroko; Goetsch, Chandra; Costa, Daniel P.; Miyashita, Kazushi

    2017-06-01

    The Transition Zone in the eastern North Pacific is important foraging habitat for many marine predators. Further, the mesopelagic depths (200-1000 m) host an abundant prey resource known as the deep scattering layer that supports deep diving predators, such as northern elephant seals, beaked whales, and sperm whales. Female northern elephant seals (Mirounga angustirostris) undertake biannual foraging migrations to this region where they feed on mesopelagic fish and squid; however, in situ measurements of prey distribution and abundance, as well as the subsurface oceanographic features in the mesopelagic Transition Zone are limited. While concurrently tracking female elephant seals during their post-molt migration, we conducted a ship-based oceanographic and hydroacoustic survey and used mesopelagic mid-water trawls to sample the deep scattering layer. We found that the abundance of mesopelagic fish at 400-600 m depth zone was the highest in the 43 °N zone, the primary foraging area of female seals. We identified twenty-nine families of fishes from the mid-water trawls, with energy-rich myctophid fishes dominating by species number, individual number, and wet weight. Biomass of mesopelagic fishes is positively correlated to annual net primary productivity; however, at the temporal and spatial scale of our study, we found no relationship between satellite derived surface primary production and prey density. Instead, we found that the subsurface chlorophyll maximum correlated with the primary elephant seal foraging regions, indicating a stronger linkage between mesopelagic ecosystem dynamics and subsurface features rather than the surface features measured with satellites. Our study not only provides insights on prey distribution in a little-studied deep ocean ecosystem, but shows that northern elephant seals are targeting the dense, species-diverse mesopelagic ecosystem at the gyre-gyre boundary that was previously inferred from their diving behavior.

  20. Amygdala Signaling during Foraging in a Hazardous Environment.

    Science.gov (United States)

    Amir, Alon; Lee, Seung-Chan; Headley, Drew B; Herzallah, Mohammad M; Pare, Denis

    2015-09-23

    We recorded basolateral amygdala (BL) neurons in a seminaturalistic foraging task. Rats had to leave their nest to retrieve food in an elongated arena inhabited by a mechanical predator. There were marked trial-to-trial variations in behavior. After poking their head into the foraging arena and waiting there for a while, rats either retreated to their nest or initiated foraging. Before initiating foraging, rats waited longer on trials that followed failed than successful trials indicating that prior experience influenced behavior. Upon foraging initiation, most principal cells (Type-1) reduced their firing rate, while in a minority (Type-2) it increased. When rats aborted foraging, Type-1 cells increased their firing rates, whereas in Type-2 cells it did not change. Surprisingly, the opposite activity profiles of Type-1 and Type-2 units were also seen in control tasks devoid of explicit threats or rewards. The common correlate of BL activity across these tasks was movement velocity, although an influence of position was also observed. Thus depending on whether rats initiated movement or not, the activity of BL neurons decreased or increased, regardless of whether threat or rewards were present. Therefore, BL activity not only encodes threats or rewards, but is closely related to behavioral output. We propose that higher order cortical areas determine task-related changes in BL activity as a function of reward/threat expectations and internal states. Because Type-1 and Type-2 cells likely form differential connections with the central amygdala (controlling freezing), this process would determine whether movement aimed at attaining food or exploration is suppressed or facilitated. Significance statement: For decades, amygdala research has been dominated by pavlovian and operant conditioning paradigms. This work has led to the view that amygdala neurons signal threats or rewards, in turn causing defensive or approach behaviors. However, the artificial circumstances of

  1. Fine-scale foraging ecology of leatherback turtles

    Directory of Open Access Journals (Sweden)

    Bryan P Wallace

    2015-02-01

    Full Text Available Remote tracking of migratory species and statistical modeling of behaviors have enabled identification of areas that are of high ecological value to these widely distributed taxa. However, direct observations at fine spatio-temporal scales are often needed to correctly interpret behaviors. In this study, we combined GPS-derived locations and archival dive records (1 sec sampling rate with animal-borne video footage from foraging leatherback turtles (Dermochelys coriacea in Nova Scotia, Canada (Northwest Atlantic Ocean to generate the most highly detailed description of natural leatherback behavior presented to date. Turtles traveled shorter distances at slower rates and increased diving rates in areas of high prey abundance, which resulted in higher prey capture rates. Increased foraging effort (e.g., dive rate, dive duration, prey handling time, number of bites was not associated with increased time at the surface breathing to replenish oxygen stores. Instead, leatherbacks generally performed short, shallow dives in the photic zone to or above the thermocline, where they disproportionately captured prey at bottoms of dives and during ascents. This foraging strategy supports visual prey detection, allows leatherbacks to exploit physically structured prey at relatively shallow depths (typically <30m, and increases time turtles spend in warmer water temperatures, thus optimizing net energy acquisition. Our results demonstrate that leatherbacks appear to be continuously foraging during daylight hours while in continental shelf waters of Nova Scotia, and that leatherback foraging behavior is driven by prey availability, not by whether or not a turtle is in a resource patch characterized by a particular size or prey density. Our study demonstrates the fundamental importance of obtaining field-based, direct observations of true behaviors at fine spatial and temporal scales to enhance our efforts to both study and manage migratory species.

  2. Patch dynamics of a foraging assemblage of bees.

    Science.gov (United States)

    Wright, David Hamilton

    1985-03-01

    The composition and dynamics of foraging assemblages of bees were examined from the standpoint of species-level arrival and departure processes in patches of flowers. Experiments with bees visiting 4 different species of flowers in subalpine meadows in Colorado gave the following results: 1) In enriched patches the rates of departure of bees were reduced, resulting in increases in both the number of bees per species and the average number of species present. 2) The reduction in bee departure rates from enriched patches was due to mechanical factors-increased flower handling time, and to behavioral factors-an increase in the number of flowers visited per inflorescence and in the number of inflorescences visited per patch. Bees foraging in enriched patches could collect nectar 30-45% faster than those foraging in control patches. 3) The quantitative changes in foraging assemblages due to enrichment, in terms of means and variances of species population sizes, fraction of time a species was present in a patch, and in mean and variance of the number of species present, were in reasonable agreement with predictions drawn from queuing theory and studies in island biogeography. 4) Experiments performed with 2 species of flowers with different corolla tube lengths demonstrated that manipulation of resources of differing availability had unequal effects on particular subsets of the larger foraging community. The arrival-departure process of bees on flowers and the immigration-extinction process of species on islands are contrasted, and the value of the stochastic, species-level approach to community composition is briefly discussed.

  3. 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.

  4. 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.

  5. Performance and carcass traits of Santa Inês lambs finished with different sources of forage

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    Adriana Morato Menezes

    2013-06-01

    Full Text Available The objective of this study was to evaluate performance and biometrics of lambs fed different sources of forage. Twenty-four six-month-old Santa Inês female lambs were randomly allocated to four experimental diets and housed in individual stalls. They weighed on average 26.35±0.20 kg. The diets were coast cross hay (HAY, cassava hay (CAS, dehydrated by-product of pea crop (PEA and saccharin (SAC. The diets were formulated with the same amount of protein and energy with fixed levels of forage (60% and concentrate (40%. Adaptation to the diet took 7 days, with 45 days on experiment. Weights and biometric measurements were obtained every fortnight and feed intake three times a week. Rights half-carcasses were weighed and sectioned into retail cuts, rib, loin, shoulder, belly, neck and leg, which were weighed individually. Weight gain in lambs was significantly different between diets, with those fed saccharin gaining more. Overall, treatments did not significantly affect biometric measurements. There was a significant difference for feed intake and live weight at the end of the experiment. Animals fed PEA and SAC showed the best results. Average positive correlations were found between biometric measurements and live weight. Treatment PEA had heavier hot (14.36 kg and cold (14.01 kg carcass weights than the other groups. Hot carcass kill-out was higher for animals fed PEA as well as ham weight, belly, neck and heart girth. The weight of the abdominal viscera (% for lambs fed CAS was greater than those fed SAC and PEA. The weights of the thoracic viscera as well as the liver, for lambs fed PEA were higher. The by-product of pea yielded best results, followed by saccharin, and can replace traditional forage sources in the region, providing similar results in terms of cuts and body components. These could be an alternative for feeding sheep in the dry season. The substitution of forages using by-product of pea and saccharin led to improved

  6. Mercury bioaccumulation and risk to three waterbird foraging guilds is influenced by foraging ecology and breeding stage

    International Nuclear Information System (INIS)

    Eagles-Smith, Collin A.; Ackerman, Joshua T.; De La Cruz, Susan E.W.; Takekawa, John Y.

    2009-01-01

    We evaluated mercury (Hg) in five waterbird species representing three foraging guilds in San Francisco Bay, CA. Fish-eating birds (Forster's and Caspian terns) had the highest Hg concentrations in thier tissues, but concentrations in an invertebrate-foraging shorebird (black-necked stilt) were also elevated. Foraging habitat was important for Hg exposure as illustrated by within-guild differences, where species more associated with marshes and salt ponds had higher concentrations than those more associated with open-bay and tidal mudflats. Importantly, Hg concentrations increased with time spent in the estuary. Surf scoter concentrations tripled over six months, whereas Forster's terns showed an up to 5-fold increase between estuary arrival and breeding. Breeding waterbirds were at elevated risk of Hg-induced reproductive impairment, particularly Forster's terns, in which 48% of breeding birds were at high risk due to their Hg levels. Our results highlight the importance of habitat and exposure timing, in addition to trophic position, on waterbird Hg bioaccumulation and risk. - The influence of foraging habitat, trophic position, and exposure timing on mercury bioaccumulation and risk to reproduction is evaluated in three waterbird guilds.

  7. 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 0.05) when diets included alfalfa hay. Total protozoa numbers and holotricha proportion were greater and less (P 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.

  8. Dental calculus reveals Mesolithic foragers in the Balkans consumed domesticated plant foods.

    Science.gov (United States)

    Cristiani, Emanuela; Radini, Anita; Edinborough, Marija; Borić, Dušan

    2016-09-13

    Researchers agree that domesticated plants were introduced into southeast Europe from southwest Asia as a part of a Neolithic "package," which included domesticated animals and artifacts typical of farming communities. It is commonly believed that this package reached inland areas of the Balkans by ∼6200 calibrated (cal.) BC or later. Our analysis of the starch record entrapped in dental calculus of Mesolithic human teeth at the site of Vlasac in the Danube Gorges of the central Balkans provides direct evidence that already by ∼6600 cal. BC, if not earlier, Late Mesolithic foragers of this region consumed domestic cereals, such as Triticum monococcum, Triticum dicoccum, and Hordeum distichon, which were also the main crops found among Early Neolithic communities of southeast Europe. We infer that "exotic" Neolithic domesticated plants were introduced to southern Europe independently almost half a millennium earlier than previously thought, through networks that enabled exchanges between inland Mesolithic foragers and early farming groups found along the Aegean coast of Turkey.

  9. Towards Drylands Biorefineries: Valorisation of Forage Opuntia for the Production of Edible Coatings

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    Alba Iris Nájera-García

    2018-06-01

    Full Text Available Species of the genus Opuntia may be a well-suited feedstock for biorefineries located in drylands, where biomass is scarcer than in humid or temperate regions. This plant has numerous uses in Mexico and Central America, and its mucilage is a specialty material with many promising applications. We extracted the mucilage from a forage species, O. heliabravoana Scheinvar, and mixed it with a thermoplastic starch to produce an edible coating. The coating was applied to blackberries, which were then evaluated in terms of several physicochemical and microbiological variables. During a 10-day evaluation period, the physicochemical variables measured in the coated fruits were not significantly different from those of the control group. However, the microbiological load of the coated fruits was significantly lower than that of the uncoated fruits, which was attributed to a decreased water activity under the edible coating. Multivariate analysis of the physicochemical and microbial variables indicated that the storage time negatively affected the weight and size of the coated and uncoated blackberries. Although some sensory attributes have yet to be optimised, our results support the use of the mucilage of forage Opuntia for the formation of edible coatings, as well as their valorisation through a biorefinery approach.

  10. Evaluation of fox tail millet (Setaria italica forage quality in different growth stages

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    F. Izadi Yazdanabadi

    2016-05-01

    Full Text Available In order to evaluate the quantitative factors in fox tail millet (Setaria italica L. under three stages of growth, an experiment was conducted in Birjand during spring and summer of 2010. The preliminary objective was evaluation of fox tail physiological characteristics on animals that feed them. Planting of Foxtail millet was performed according to local practices and endemic acknowledge. Sampling was carried out at Vegetative, flowering and seeding stages, then samples transported to laboratory of animal nutrition. After Drying of sampling, dry matter, dry matter digestibility, crude protein, metabolically energy, Acid Detergent Fiber and Nitrogen Detergent Fiber, Ash and some mineral nutrients were measured. The results showed significant differences in measured characteristics in various phonological stages. Forage quality was higher in flowering and seeding stages than in vegetative stage. Dry matter digestibility and metabolically energy were high and NDF and ADF were less in vegetative stage. Because fox tail millet is leafy and palatable by animal at this stage, it’s optimum yield is important. Ability to produce Green fodder by this plant and the possibility of cultivation in different regions and its ability to produce forage for livestocks, its planting is recommended.

  11. 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

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    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

  12. 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.

  13. 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.

  14. PRODUCTIVE IMPACT OF THE GREEN FORAGE SUPPLY USAGE AT THE DAIRY FARMS

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    LAVINIA MOISE

    2007-05-01

    Full Text Available This paper presents the importance of the crop structure as a tool to maximize efficiency in the conceiving of the green forage supply scheme in a dairy farm. Several apects are necessary to consider for proper green forage utilization by the cattle, as follows: climatic conditions, proper field operations for each crop, optimal harvest date, and farm technical and economical resources. With a high degree of succulence, green forage and derived products (silage, haylage, present addvantages as compared to hay, having superior indices of nutritive value and palatability. A green forage supply scheme was applied on an area of 188 ha taking into account dairy cattle biological traits. Crop structure was as follows: forage maize, Sudan grass, Italian ryegrass, new lucern and old lucerne, and orchardgrass. Insuring the required superior green forage for the dairy cattle according to forage rations, represents one of the main techniques to maximize milk production and to minimize milk production cost.

  15. Multi-Robot Item Delivery and Foraging: Two Sides of a Coin

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    Somchaya Liemhetcharat

    2015-09-01

    Full Text Available Multi-robot foraging has been widely studied in the literature, and the general assumption is that the robots are simple, i.e., with limited processing and carrying capacity. We previously studied continuous foraging with slightly more capable robots, and in this article, we are interested in using similar robots for item delivery. Interestingly, item delivery and foraging are two sides of the same coin: foraging an item from a location is similar to satisfying a demand. We formally define the multi-robot item delivery problem and show that the continuous foraging problem is a special case of it. We contribute distributed multi-robot algorithms that solve the item delivery and foraging problems and describe how our shared world model is synchronized across the multi-robot team. We performed extensive experiments on simulated robots using a Java simulator, and we present our results to demonstrate that we outperform benchmark algorithms from multi-robot foraging.

  16. 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.

  17. Livestock forage and mineral relations on a shrub-steppe rangeland in northwestern United States of America

    International Nuclear Information System (INIS)

    Uresk, D.W.; Rickard, W.H.

    1976-01-01

    The study area is the Arid Lands Ecology (ALE) Reserve, a portion of the United States Energy Research and Development Administration's Hanford Reservation located in the semi-arid region of south-central Washington. Small experimental pastures were subjected to four consecutive years of moderate spring grazing by yearling steers. These pastures are unique in that they represent grazing stresses imposed upon previously ungrazed (by livestock) plant communities. These communities had been protected from grazing by livestock for more than 30 years under ERDA management. Bluebunch wheatgrass (Agropyron spicatum), the dominant species, was the major forage plant in the diet of the steers during the 1974 grazing season, followed by Cusick's bluegrass (Poa cusickii), Thurber's needlegrass (Stipa thurberiania) and hawksbeard (Crepis atrabarba). These four species made up approximately 93% of the total diet. The forage intake ranged from 9.9 kg/head daily to 10.9 kg/head daily during the grazing season. During this period, these steers gained a total of 21.6 kg/ha live weight. Fifteen kg of forage consumed produces 1 kg of live steer for a 6.7% conversion. The conversion rate for crude protein was 12.7%, 83.3% for phosphorus and 25.6% for calcium. (author)

  18. Relationship between legacy and emerging organic pollutants in Antarctic seabirds and their foraging ecology as shown by δ13C and δ15N.

    Science.gov (United States)

    Mello, Flávia V; Roscales, Jose L; Guida, Yago S; Menezes, Jorge F S; Vicente, Alba; Costa, Erli S; Jiménez, Begoña; Torres, João Paulo M

    2016-12-15

    Foraging ecology and the marine regions exploited by Antarctic seabirds outside of breeding strongly influence their exposure to persistent organic pollutants (POPs). However, relationships between them are largely unknown, an important knowledge gap given that many species are capital breeders and POPs may be deleterious to seabirds. This study investigates the relationship between Antarctic seabird foraging ecology (measured by δ 13 C and δ 15 N) and POPs accumulated in their eggs prior to breeding. Organochlorinated pesticides, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dechlorane plus (DP) were measured in eggs of chinstrap, Adélie, and gentoo penguins (Pygoscelis antarctica, P. adeliae, P. papua), as well as south polar skua (Catharacta maccormicki), sampled on King George Island. Total POP levels were as follows: skua (3210±3330ng/g lipid weight)>chinstrap (338±128ng/g)>Adélie (287±43.3ng/g)>gentoo (252±49.4ng/g). Trophic position and pre-breeding foraging sites were important in explaining POP accumulation patterns across species. The most recalcitrant compounds were preferentially accumulated in skuas, occupying one trophic level above penguins. In contrast, their Antarctic endemism, coupled with influence from cold condensation of pollutants, likely contributed to penguins exhibiting higher concentrations of more volatile compounds (e.g., hexachlorobenzene, PCB-28 and -52) than skuas. Regional differences in penguin pre-breeding foraging areas did not significantly affect their POP burdens, whereas the trans-equatorial migration and foraging sites of skuas were strongly reflected in their pollutant profiles, especially for PBDEs and DPs. Overall, our results provide new insights on migratory birds as biovectors of POPs, including non-globally regulated compounds such as DP, from northern regions to Antarctica. Copyright © 2016. Published by Elsevier B.V.

  19. The effect of prey density on foraging mode selection in juvenile lumpfish: balancing food intake with the metabolic cost of foraging.

    Science.gov (United States)

    Killen, Shaun S; Brown, Joseph A; Gamperl, A Kurt

    2007-07-01

    1. In many species, individuals will alter their foraging strategy in response to changes in prey density. However, previous work has shown that prey density has differing effects on the foraging mode decisions of ectotherms as compared with endotherms. This is likely due to differences in metabolic demand; however, the relationship between metabolism and foraging mode choice in ectotherms has not been thoroughly studied. 2. Juvenile lumpfish Cyclopterus lumpus forage using one of two modes: they can actively search for prey while swimming, or they can 'sit-and-wait' for prey while clinging to the substrate using a ventral adhesive disk. The presence of these easily distinguishable foraging modes makes juvenile lumpfish ideal for the study of foraging mode choice in ectotherms. 3. Behavioural observations conducted during laboratory experiments showed that juvenile lumpfish predominantly use the 'cling' foraging mode when prey is abundant, but resort to the more costly 'swim' mode to seek out food when prey is scarce. The metabolic cost of active foraging was also quantified for juvenile lumpfish using swim-tunnel respirometry, and a model was devised to predict the prey density at which lumpfish should switch between the swim and cling foraging modes to maximize energy intake. 4. The results of this model do not agree with previous observations of lumpfish behaviour, and thus it appears that juvenile lumpfish do not try to maximize their net energetic gain. Instead, our data suggest that juvenile lumpfish forage in a manner that reduces activity and conserves space in their limited aerobic scope. This behavioural flexibility is of great benefit to this species, as it allows young individuals to divert energy towards growth as opposed to activity. In a broader context, our results support previous speculation that ectotherms often forage in a manner that maintains a minimum prey encounter rate, but does not necessarily maximize net energy gain.

  20. Evaluation of the content of neutral detergent fiber and acid through different procedures applied to forage plants

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    Luiz Juliano Valério Geron

    2014-06-01

    Full Text Available This study aimed to evaluate the content of neutral detergent fiber (NDF and acid (FDA of Marandu, Humidicula; Massai; Mombaça grass obtained by three different procedures with the conventional method (CON, the Filter Bag Technique Ankom® (FBT and adapted by EMBRAPA (EMB. The forage plants were obtained in the Southwest region of Mato Grosso in the September; the samples were collected from pastures planted the three years. There were three batteries (runs for each procedure (method for the determination of NDF and ADF of different forages. There were realised three batteries (runs for each procedure (method for the determination of NDF and ADF of different forages. We used a completely randomized design with three replications for each methodology. Statistical analysis of the variables studied was performed by analysis of variance and the differences obtained were analyzed by Tukey test, considering 5% significance level. It was observed that the different procedures (CON, FBT and EMB to determine the content NDF did not differ between them for different forages plants, with average values of 78.61% and 74.96% for the Marandu and Humidicula grass, respectively and 76.78% and 73.08% for Massai and Mombaça grass, respectively. The ADF content obtained by different procedures (CON, FBT and EMB showed no difference between them, with average values of 50.95% and 44.86% for Marandu and Humidicula grass, respectively and 52.21% and 51.56% for Massai and Mombaça grass, respectively. Thus, it is concluded that the content of neutral detergent fiber and acid Marandu, Humidicula; Massai and Mombaça grass can be determined by the procedure adapted by EMBRAPA, since this was not different compared to conventional methodology and the Filter Bag Technique Ankom®, besides having a lower waste of reagents and consequently lower cost.

  1. Do bigger bats need more time to forage?

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    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.

  2. 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.

  3. Limestone doses affecting mineral contents in tropical grass forage

    International Nuclear Information System (INIS)

    Armelin, M.J.A.; Saiki, M.

    2005-01-01

    Field trial was performed at the experimental farm of Southeast Embrapa Cattle, Sao Carlos - SP, Brazil, on a 16 year old Brachiaria decumbens pasture, grown on a distrophic Hapludox (Oxisol), recovered by the use of limestone and fertilizer. The experiments were carried out in random blocks, with 6 replications and 5 treatments. The 100 m 2 blocks were established in the pasture. Each block received a sequence of limestone doses of 0, 1, 2, 4 and 8 t/ha. The forage samples were taken one year after limestone application on soil surface. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine mineral contents. The statistical analysis showed a negative linear correlation of Br, Co, Cr, Mn and Zn contents in forage with the limestone doses, while the uptake of Mg was affected in a positive way. (author)

  4. Artificial root foraging optimizer algorithm with hybrid strategies

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2017-02-01

    Full Text Available In this work, a new plant-inspired optimization algorithm namely the hybrid artificial root foraging optimizion (HARFO is proposed, which mimics the iterative root foraging behaviors for complex optimization. In HARFO model, two innovative strategies were developed: one is the root-to-root communication strategy, which enables the individual exchange information with each other in different efficient topologies that can essentially improve the exploration ability; the other is co-evolution strategy, which can structure the hierarchical spatial population driven by evolutionary pressure of multiple sub-populations that ensure the diversity of root population to be well maintained. The proposed algorithm is benchmarked against four classical evolutionary algorithms on well-designed test function suites including both classical and composition test functions. Through the rigorous performance analysis that of all these tests highlight the significant performance improvement, and the comparative results show the superiority of the proposed algorithm.

  5. Foraging dives by post-breeding northern pintails

    Science.gov (United States)

    Miller, Michael R.

    1983-01-01

    Dabbling ducks (Anatini), including Northern Pintails (Anas acuta), typically feed by “tipping-up” (Bellrose, Ducks, Geese, and Swans of North America, Stackpole Books, Harrisburg, Pennsylvania, 1976) in shallow water. Pintails are not as adapted for diving as members of Aythyini or Oxyurini (Catlett and Johnston, Comp. Biochem. Physiol. 47A:925-931, 1974); however, incidents of foraging dives by small numbers of pintails have been reported (Chapman et al., Br. Birds 52:60, 1959; Bourget and Chapdelaine, Wildfowl 26:55-57, 1975). This paper reports on forage diving by a flock of several hundred pintails. Ecological explanations are suggested to account for the behavior and comparisons with tip-up feeding are presented.

  6. Actions speak louder than words in socially foraging human groups.

    Science.gov (United States)

    Sumner, Seirian; King, Andrew J

    2011-11-01

    SOCIAL FORAGING IN HUMANS HAS A DEEP EVOLUTIONARY HISTORY: early hominids searched for dispersed food sources in a patchy, uncertain environment. A fundamental assumption is that social foragers benefit by exchanging information about food sources, in order to make collective decisions based on pooled information. We conducted the first experimental test of this assumption, and showed that, as predicted, communication significantly enhanced group performance. A further, unexpected result was that physical communication through gesturing, rather than verbal communication, appeared to play a crucial role in the early stages of group interaction, facilitating consensus decision making by groups.  The importance of gestures in human interactions may therefore be underestimated, and this has important implications for modern human societies, where communications are becoming increasingly dominated by virtual modes of communication that preclude the use of gestures. 

  7. 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.

  8. Quality and Quantity Evaluations of Shade Grown Forages

    Science.gov (United States)

    K. P. Ladyman; M. S. Kerley; R. L. Kallenbach; H. E. Garrett; J. W. Van Sambeek; N. E. Navarrete-Tindall

    2003-01-01

    Seven legumes were grown during the summer-fall of 2000, at the Horticulture and Agroforestry Research Center (39? 01 ' N, 92? 46' W) near New Franklin, MO. The forages were grown in 7.5L white pots placed on light-colored gravel either under full sunlight, 45% sunlight, or 20% sunlight created by a shade cloth over a rectangular frame. Drip irrigation was...

  9. Valuation of pollinator forage services provided by Eucalyptus Cladocalyx

    CSIR Research Space (South Africa)

    De Lange, Willem J

    2013-08-01

    Full Text Available legislation does not allow the importation of bees for pollination services from outside the province, the risk of unsecured forage is increased. Pollination replacement option All insect pollinators Managed pollinators Wild pollinators US$ millions...). Furthermore, colony collapse disorder outbreaks along with increases in sightings of predatory Vespula Germanica (German wasp or “yellow jackets”) in the Western Cape not only add to the pressure on the beekeeping industry, but also the wild pollinator...

  10. 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.

  11. Vision and foraging in cormorants: more like herons than hawks?

    Directory of Open Access Journals (Sweden)

    Craig R White

    Full Text Available BACKGROUND: Great cormorants (Phalacrocorax carbo L. show the highest known foraging yield for a marine predator and they are often perceived to be in conflict with human economic interests. They are generally regarded as visually-guided, pursuit-dive foragers, so it would be expected that cormorants have excellent vision much like aerial predators, such as hawks which detect and pursue prey from a distance. Indeed cormorant eyes appear to show some specific adaptations to the amphibious life style. They are reported to have a highly pliable lens and powerful intraocular muscles which are thought to accommodate for the loss of corneal refractive power that accompanies immersion and ensures a well focussed image on the retina. However, nothing is known of the visual performance of these birds and how this might influence their prey capture technique. METHODOLOGY/PRINCIPAL FINDINGS: We measured the aquatic visual acuity of great cormorants under a range of viewing conditions (illuminance, target contrast, viewing distance and found it to be unexpectedly poor. Cormorant visual acuity under a range of viewing conditions is in fact comparable to unaided humans under water, and very inferior to that of aerial predators. We present a prey detectability model based upon the known acuity of cormorants at different illuminances, target contrasts and viewing distances. This shows that cormorants are able to detect individual prey only at close range (less than 1 m. CONCLUSIONS/SIGNIFICANCE: We conclude that cormorants are not the aquatic equivalent of hawks. Their efficient hunting involves the use of specialised foraging techniques which employ brief short-distance pursuit and/or rapid neck extension to capture prey that is visually detected or flushed only at short range. This technique appears to be driven proximately by the cormorant's limited visual capacities, and is analogous to the foraging techniques employed by herons.

  12. Root foraging performance and life-history traits

    Czech Academy of Sciences Publication Activity Database

    Weiser, M.; Koubek, T.; Herben, Tomáš

    2016-01-01

    Roč. 7, JUN 9 (2016), s. 1-9, č. článku 779. ISSN 1664-462X R&D Projects: GA ČR GAP505/12/1007; GA ČR(CZ) GA16-19245S Institutional support: RVO:67985939 Keywords : root foraging * phenotypic plasticity * clonal plants Subject RIV: EF - Botanics Impact factor: 4.298, year: 2016

  13. Experimental Evidence that Social Relationships Determine Individual Foraging Behavior

    OpenAIRE

    Firth, Josh A.; Voelkl, Bernhard; Farine, Damien R.; Sheldon, Ben C.

    2015-01-01

    Social relationships are fundamental to animals living in complex societies [1-3]. The extent to which individuals base their decisions around their key social relationships, and the consequences this has on their behavior and broader population level processes, remains unknown. Using a novel experiment that controlled where individual wild birds (great tits, Parus major) could access food, we restricted mated pairs from being allowed to forage at the same locations. This introduced a conflic...

  14. Sexy birds are superior at solving a foraging problem.

    Science.gov (United States)

    Mateos-Gonzalez, Fernando; Quesada, Javier; Senar, Juan Carlos

    2011-10-23

    Yellow, red or orange carotenoid-based colorations in male birds are often a signal to prospecting females about body condition, health status and ability to find food. However, this general 'ability to find food' has never been defined. Here we show that more brightly ornamented individuals may also be more efficient when foraging in novel situations. The results highlight the fact that evolution may have provided females tools to evaluate cognitive abilities of the males.

  15. A Breath of Fresh Air in Foraging Theory: The Importance of Wind for Food Size Selection in a Central-Place Forager.

    Science.gov (United States)

    Alma, Andrea Marina; Farji-Brener, Alejandro G; Elizalde, Luciana

    2017-09-01

    Empirical data about food size carried by central-place foragers do not often fit with the optimum predicted by classical foraging theory. Traditionally, biotic constraints such as predation risk and competition have been proposed to explain this inconsistency, leaving aside the possible role of abiotic factors. Here we documented how wind affects the load size of a central-place forager (leaf-cutting ants) through a mathematical model including the whole foraging process. The model showed that as wind speed at ground level increased from 0 to 2 km/h, load size decreased from 91 to 30 mm 2 , a prediction that agreed with empirical data from windy zones, highlighting the relevance of considering abiotic factors to predict foraging behavior. Furthermore, wind reduced the range of load sizes that workers should select to maintain a similar rate of food intake and decreased the foraging rate by ∼70% when wind speed increased 1 km/h. These results suggest that wind could reduce the fitness of colonies and limit the geographic distribution of leaf-cutting ants. The developed model offers a complementary explanation for why load size in central-place foragers may not fit theoretical predictions and could serve as a basis to study the effects of other abiotic factors that influence foraging.

  16. 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.

  17. Beneficial Effects of Temperate Forage Legumes that Contain Condensed Tannins

    Directory of Open Access Journals (Sweden)

    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. Bust economics: foragers choose high quality habitats in lean times

    Directory of Open Access Journals (Sweden)

    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.

  20. Dietary variation and stress among prehistoric Jomon foragers from Japan.

    Science.gov (United States)

    Temple, Daniel H

    2007-08-01

    Current archaeological evidence indicates that greater dietary reliance on marine resources is recorded among the eastern Jomon, while plant dependence prevailed in western/inland Japan. The hypothesis that the dietary choices of the western/inland Jomon will be associated with greater systemic stress is tested by comparing carious tooth and enamel hypoplasia frequencies between the eastern and western/inland Jomon. Demographic collapse coincides with climate change during the Middle to Late Jomon period, suggesting dwindling resource availability. It is hypothesized that this change was associated with greater systemic stress and/or dietary change among the Middle to Late Jomon. This hypothesis is tested by comparing enamel hypoplasia and carious tooth frequencies between Middle to Late and Late to Final Jomon foragers. Enamel hypoplasia was significantly more prevalent among the western/inland Jomon. Such findings are consistent with archaeological studies that argue for greater plant consumption and stresses associated with seasonal resource depletion among the western/inland Jomon. Approximately equivalent enamel hypoplasia frequencies between Middle to Late and Late to Final Jomon foragers argues against a demographic collapse in association with diminished nutritional returns. Significant differences in carious tooth frequencies are, however, observed between Middle to Late and Late to Final Jomon foragers. These results suggest a subsistence shift during the Middle to Late Jomon period, perhaps in response to a changed climate. The overall patterns of stress documented by this study indicate wide-spread environmentally directed biological variation among the prehistoric Jomon. (c) 2007 Wiley-Liss, Inc.

  1. Nitrogen Transfer to Forage Crops from a Caragana Shelterbelt

    Directory of Open Access Journals (Sweden)

    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.

  2. 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.

  3. MACRO NUTRIENTS UPTAKE OF FORAGE GRASSES AT DIFFERENT SALINITY STRESSES

    Directory of Open Access Journals (Sweden)

    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.

  4. 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. PMID:25025334

  5. Inductive foraging: improving the diagnostic yield of primary care consultations.

    Science.gov (United States)

    Donner-Banzhoff, Norbert; Hertwig, Ralph

    2014-03-01

    Physicians attempting to make a diagnosis arrive at specific hypotheses early in their encounter with patients. Further data are collected in the light of these early hypotheses. While this hypothetico-deductive model has been accepted as both a description of physicians' data gathering and a norm, little attention has been paid to the preceding stage of the consultation. It is suggested that 'inductive foraging' is a relevant and appropriate mode of data acquisition for the first part of the patient encounter. Research evidence from cognitive psychology and medical reasoning research is discussed. With inductive foraging, 'pattern failure' rather than 'pattern recognition' is the mode of discovery. Largely, guidance should be left to the patient to lead the clinician into areas where departures from normality are to be found. This is in contrast to active and focused 'deductive inquiry,' which should be used only after most aetiologies, but a few have eliminated. Especially when the prevalence of serious disease is low, and a wide range of diagnoses must be evaluated, such as in General Practice, inductive foraging is a rational and efficient diagnostic strategy. Previously, too little attention has been paid to the initial stage of the consultation. Premature closure at this point may result in diagnostic error.

  6. Production of tropical forage grasses under different shading levels

    Directory of Open Access Journals (Sweden)

    Francisco Eduardo Torres

    2017-12-01

    Full Text Available This study aimed to evaluate the forage production of three tropical forage grasses under different shading levels. The experiment was conducted in a greenhouse at Universidade Estadual de Mato Grosso do Sul, University Unit of Aquidauana (UEMS/UUA, in a soil classified as Ultisol sandy loam texture. The treatments consisted of three grasses species combinations (B. brizantha cv. Marandu, B. decumbens cv. Basilisck and Panicum maximum cv. Tanzania, submitted to four shading levels (0, 30, 50 and 75%, arranged in a completely randomized blocks design in a factorial 3 x 4, with eight replications. After harvest, the plants were separated into shoot and roots for determination of shoot fresh mass (SFM, shoot dry mass (SDM and roots dry mass production. After analysis of variance, the qualitative factor was subjected to comparison of averages by Tukey’s test, and the quantitative factor to analysis of polynomial regression, being interactions appropriately unfolded. It was verified that B. decumbens, by its linearly increasing production of forage and less decrease of root formation, is the most recommended for shading conditions compared to grasses Tanzania and Marandu.

  7. Experimental Evidence that Social Relationships Determine Individual Foraging Behavior.

    Science.gov (United States)

    Firth, Josh A; Voelkl, Bernhard; Farine, Damien R; Sheldon, Ben C

    2015-12-07

    Social relationships are fundamental to animals living in complex societies. The extent to which individuals base their decisions around their key social relationships, and the consequences this has on their behavior and broader population level processes, remains unknown. Using a novel experiment that controlled where individual wild birds (great tits, Parus major) could access food, we restricted mated pairs from being allowed to forage at the same locations. This introduced a conflict for pair members between maintaining social relationships and accessing resources. We show that individuals reduce their own access to food in order to sustain their relationships and that individual foraging activity was strongly influenced by their key social counterparts. By affecting where individuals go, social relationships determined which conspecifics they encountered and consequently shaped their other social associations. Hence, while resource distribution can determine individuals' spatial and social environment, we illustrate how key social relationships themselves can govern broader social structure. Finally, social relationships also influenced the development of social foraging strategies. In response to forgoing access to resources, maintaining pair bonds led individuals to develop a flexible "scrounging" strategy, particularly by scrounging from their pair mate. This suggests that behavioral plasticity can develop to ameliorate conflicts between social relationships and other demands. Together, these results illustrate the importance of considering social relationships for explaining behavioral variation due to their significant impact on individual behavior and demonstrate the consequences of key relationships for wider processes. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Stochastic resonance and the evolution of Daphnia foraging strategy

    International Nuclear Information System (INIS)

    Dees, Nathan D; Bahar, Sonya; Moss, Frank

    2008-01-01

    Search strategies are currently of great interest, with reports on foraging ranging from albatrosses and spider monkeys to microzooplankton. Here, we investigate the role of noise in optimizing search strategies. We focus on the zooplankton Daphnia, which move in successive sequences consisting of a hop, a pause and a turn through an angle. Recent experiments have shown that their turning angle distributions (TADs) and underlying noise intensities are similar across species and age groups, suggesting an evolutionary origin of this internal noise. We explore this hypothesis further with a digital simulation (EVO) based solely on the three central Darwinian themes: inheritability, variability and survivability. Separate simulations utilizing stochastic resonance (SR) indicate that foraging success, and hence fitness, is maximized at an optimum TAD noise intensity, which is represented by the distribution's characteristic width, σ. In both the EVO and SR simulations, foraging success is the criterion, and the results are the predicted characteristic widths of the TADs that maximize success. Our results are twofold: (1) the evolving characteristic widths achieve stasis after many generations; (2) as a hop length parameter is changed, variations in the evolved widths generated by EVO parallel those predicted by SR. These findings provide support for the hypotheses that (1) σ is an evolved quantity and that (2) SR plays a role in evolution. (communication)

  9. Eye Size, Fovea, and Foraging Ecology in Accipitriform Raptors.

    Science.gov (United States)

    Potier, Simon; Mitkus, Mindaugas; Bonadonna, Francesco; Duriez, Olivier; Isard, Pierre-François; Dulaurent, Thomas; Mentek, Marielle; Kelber, Almut

    2017-01-01

    Birds with larger eyes are predicted to have higher spatial resolution because of their larger retinal image. Raptors are well known for their acute vision, mediated by their deep central fovea. Because foraging strategies may demand specific visual adaptations, eye size and fovea may differ between species with different foraging ecology. We tested whether predators (actively hunting mobile prey) and carrion eaters (eating dead prey) from the order Accipitriformes differ in eye size, foveal depth, and retinal thickness using spectral domain optical coherence tomography and comparative phylogenetic methods. We found that (1) all studied predators (except one) had a central and a temporal fovea, but all carrion eaters had only the central fovea; (2) eye size scaled with body mass both in predators and carrion eaters; (3) predators had larger eyes relative to body mass and a thicker retina at the edge of the fovea than carrion eaters, but there was no difference in the depth of the central fovea between the groups. Finally, we found that (4) larger eyes generally had a deeper central fovea. These results suggest that the visual system of raptors within the order Accipitriformes may be highly adapted to the foraging strategy, except for the foveal depth, which seems mostly dependent upon the eye size. © 2017 S. Karger AG, Basel.

  10. Resource heterogeneity and foraging behaviour of cattle across spatial scales

    Directory of Open Access Journals (Sweden)

    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.

  11. GPS tracking devices reveal foraging strategies of black-legged kittiwakes

    Science.gov (United States)

    Kotzerka, Jana; Garthe, Stefan; Hatch, Scott A.

    2010-01-01

    The Black-legged Kittiwake Rissa tridactyla is the most abundant gull species in the world, but some populations have declined in recent years, apparently due to food shortage. Kittiwakes are surface feeders and thus can compensate for low food availability only by increasing their foraging range and/or devoting more time to foraging. The species is widely studied in many respects, but long-distance foraging and the limitations of conventional radio telemetry have kept its foraging behavior largely out of view. The development of Global Positioning System (GPS) loggers is advancing rapidly. With devices as small as 8 g now available, it is possible to use this technology for tracking relatively small species of oceanic birds like kittiwakes. Here we present the first results of GPS telemetry applied to Black-legged Kittiwakes in 2007 in the North Pacific. All but one individual foraged in the neritic zone north of the island. Three birds performed foraging trips only close to the colony (within 13 km), while six birds had foraging ranges averaging about 40 km. The maximum foraging range was 59 km, and the maximum distance traveled was 165 km. Maximum trip duration was 17 h (mean 8 h). An apparently bimodal distribution of foraging ranges affords new insight on the variable foraging behaviour of Black-legged Kittiwakes. Our successful deployment of GPS loggers on kittiwakes holds much promise for telemetry studies on many other bird species of similar size and provides an incentive for applying this new approach in future studies.

  12. 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. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

  13. Behavioural environments and niche construction: the evolution of dim-light foraging in bees.

    Science.gov (United States)

    Wcislo, William T; Tierney, Simon M

    2009-02-01

    Most bees forage for floral resources during the day, but temporal patterns of foraging activity vary extensively, and foraging in dim-light environments has evolved repeatedly. Facultative dim-light foraging behaviour is known in five of nine families of bees, while obligate behaviour is known in four families and evolved independently at least 19 times. The light intensity under which bees forage varies by a factor of 10(8), and therefore the evolution of dim-light foraging represents the invasion of a new, extreme niche. The repeated evolution of dim-light foraging behaviour in bees allows tests of the hypothesis that behaviour acts as an evolutionary pacemaker. With the exception of one species of Apis, facultative dim-light foragers show no external structural traits that are thought to enable visually mediated flight behaviour in low-light environments. By contrast, most obligate dim-light foragers show a suite of convergent optical traits such as enlarged ocelli and compound eyes. In one intensively studied species (Megalopta genalis) these optical changes are associated with neurobiological changes to enhance photon capture. The available ecological evidence suggests that an escape from competition for pollen and nectar resources and avoidance of natural enemies are driving factors in the evolution of obligate dim-light foraging.

  14. Environmental variability drives shifts in the foraging behaviour and reproductive success of an inshore seabird.

    Science.gov (United States)

    Kowalczyk, Nicole D; Reina, Richard D; Preston, Tiana J; Chiaradia, André

    2015-08-01

    Marine animals forage in areas that aggregate prey to maximize their energy intake. However, these foraging 'hot spots' experience environmental variability, which can substantially alter prey availability. To survive and reproduce animals need to modify their foraging in response to these prey shifts. By monitoring their inter-annual foraging behaviours, we can understand which environmental variables affect their foraging efficiency, and can assess how they respond to environmental variability. Here, we monitored the foraging behaviour and isotopic niche of little penguins (Eudyptula minor), over 3 years (2008, 2011, and 2012) of climatic and prey variability within Port Phillip Bay, Australia. During drought (2008), penguins foraged in close proximity to the Yarra River outlet on a predominantly anchovy-based diet. In periods of heavy rainfall, when water depth in the largest tributary into the bay (Yarra River) was high, the total distance travelled, maximum distance travelled, distance to core-range, and size of core- and home-ranges of penguins increased significantly. This larger foraging range was associated with broad dietary diversity and high reproductive success. These results suggest the increased foraging range and dietary diversity of penguins were a means to maximize resource acquisition rather than a strategy to overcome local depletions in prey. Our results demonstrate the significance of the Yarra River in structuring predator-prey interactions in this enclosed bay, as well as the flexible foraging strategies of penguins in response to environmental variability. This plasticity is central to the survival of this small-ranging, resident seabird species.

  15. Hive Relocation Does Not Adversely Affect Honey Bee (Hymenoptera: Apidae Foraging

    Directory of Open Access Journals (Sweden)

    Fiona C. Riddell Pearce

    2013-01-01

    Full Text Available Honey bees, Apis mellifera, face major challenges including diseases and reduced food availability due to agricultural intensification. Additionally, migratory beekeeping may subject colonies to a moving stress, both during the move itself and after the move, from the bees having to forage in a novel environment where they have no knowledge of flower locations. This study investigated the latter. We moved three colonies housed in observation hives onto the campus from a site 26 km away and compared their foraging performance to three similarly sized colonies at the same location that had not been moved. We obtained data on (1 foraging performance by calculating distance by decoding waggle dances, (2 hive foraging rate by counting forager departure rate, (3 forage quality by assessing sugar content of nectar from returning foragers, and (4 forager success by calculating the proportion of bees returning to the nest entrance with nectar in their crop. We repeated this 3 times (August 2010, October 2010, and June 2011 to encompass any seasonal effects. The data show no consistent difference in foraging performance of moved versus resident hives. Overall the results suggest that moving to a new location does not adversely affect the foraging success of honey bees.

  16. Root foraging increases performance of the clonal plant Potentilla reptans in heterogeneous nutrient environments.

    Science.gov (United States)

    Wang, Zhengwen; van Kleunen, Mark; During, Heinjo J; Werger, Marinus J A

    2013-01-01

    Plastic root-foraging responses have been widely recognized as an important strategy for plants to explore heterogeneously distributed resources. However, the benefits and costs of root foraging have received little attention. In a greenhouse experiment, we grew pairs of connected ramets of 22 genotypes of the stoloniferous plant Potentilla reptans in paired pots, between which the contrast in nutrient availability was set as null, medium and high, but with the total nutrient amount kept the same. We calculated root-foraging intensity of each individual ramet pair as the difference in root mass between paired ramets divided by the total root mass. For each genotype, we then calculated root-foraging ability as the slope of the regression of root-foraging intensity against patch contrast. For all genotypes, root-foraging intensity increased with patch contrast and the total biomass and number of offspring ramets were lowest at high patch contrast. Among genotypes, root-foraging intensity was positively related to production of offspring ramets and biomass in the high patch-contrast treatment, which indicates an evolutionary benefit of root foraging in heterogeneous environments. However, we found no significant evidence that the ability of plastic foraging imposes costs under homogeneous conditions (i.e. when foraging is not needed). Our results show that plants of P. reptans adjust their root-foraging intensity according to patch contrast. Moreover, the results show that the root foraging has an evolutionary advantage in heterogeneous environments, while costs of having the ability of plastic root foraging were absent or very small.

  17. 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.

  18. 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 concentratio...... of plant growth and root activity, increasing the rate of nitrate uptake. Data presented in this article support a role for cyanogenic glucosides in mitigating oxidative stress....... of nitrate, also potentially toxic to ruminants, may accumulate during or shortly after periods of drought. Little is known about the degree and duration of drought-stress required to induce dhurrin accumulation, or how changes in dhurrin concentration are influenced by plant size or nitrate metabolism....... 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...

  19. 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

    additional data are necessary to understand the relationship among turbidity plumes, behavior of CLT prey fish , and CLT foraging behavior. KBC...activities. Fish actively seek out or avoid turbid waters for a number of reasons, including predator avoidance and food resources, and this...Birds 14:57-72. Atwood, J. L., and P. R. Kelly. 1984. Fish dropped on breeding colonies as indicators of Least Tern food habits. Wilson Bulletin 96: 34

  20. Autonomous gliders reveal features of the water column associated with foraging by adelie penguins.

    Science.gov (United States)

    Kahl, L Alex; Schofield, Oscar; Fraser, William R

    2010-12-01

    Despite their strong dependence on the pelagic environment, seabirds and other top predators in polar marine ecosystems are generally studied during their reproductive phases in terrestrial environments. As a result, a significant portion of their life history is understudied which in turn has led to limited understanding. Recent advances in autonomous underwater vehicle (AUV) technologies have allowed satellite-tagged Adélie penguins to guide AUV surveys of the marine environment at the Palmer Long-Term Ecological Research (LTER) site on the western Antarctic Peninsula. Near real-time data sent via Iridium satellites from the AUVs to a centralized control center thousands of miles away allowed scientists to adapt AUV sampling strategies to meet the changing conditions of the subsurface. Such AUV data revealed the water masses and fine-scale features associated with Adélie penguin foraging trips. During this study, the maximum concentration of chlorophyll was between 30 and 50 m deep. Encompassing this peak in the chlorophyll concentration, within the water-column, was a mixture of nutrient-laden Upper Circumpolar Deep (UCDW) and western Antarctic Peninsula winter water (WW). Together, data from the AUV survey and penguin dives reveal that 54% of foraging by Adélie penguins occurs immediately below the chlorophyll maximum. These data demonstrate how bringing together emerging technologies, such as AUVs, with established methods such as the radio-tagging of penguins can provide powerful tools for monitoring and hypothesis testing of previously inaccessible ecological processes. Ocean and atmosphere temperatures are expected to continue increasing along the western Antarctic Peninsula, which will undoubtedly affect regional marine ecosystems. New and emerging technologies such as unmanned underwater vehicles and individually mounted satellite tracking devices will provide the tools critical to documenting and understanding the widespread ecological change

  1. Increasing evidence that bats actively forage at wind turbines.

    Science.gov (United States)

    Foo, Cecily F; Bennett, Victoria J; Hale, Amanda M; Korstian, Jennifer M; Schildt, Alison J; Williams, Dean A

    2017-01-01

    Although the ultimate causes of high bat fatalities at wind farms are not well understood, several lines of evidence suggest that bats are attracted to wind turbines. One hypothesis is that bats would be attracted to turbines as a foraging resource if the insects that bats prey upon are commonly present on and around the turbine towers. To investigate the role that foraging activity may play in bat fatalities, we conducted a series of surveys at a wind farm in the southern Great Plains of the US from 2011-2016. From acoustic monitoring we recorded foraging activity, including feeding buzzes indicative of prey capture, in the immediate vicinity of turbine towers from all six bat species known to be present at this site. From insect surveys we found Lepidoptera, Coleoptera, and Orthoptera in consistently high proportions over several years suggesting that food resources for bats were consistently available at wind turbines. We used DNA barcoding techniques to assess bat diet composition of (1) stomach contents from 47 eastern red bat ( Lasiurus borealis ) and 24 hoary bat ( Lasiurus cinereus ) carcasses collected in fatality searches, and (2) fecal pellets from 23 eastern red bats that were found on turbine towers, transformers, and tower doors. We found that the majority of the eastern red bat and hoary bat stomachs, the two bat species most commonly found in fatality searches at this site, were full or partially full, indicating that the bats were likely killed while foraging. Although Lepidoptera and Orthoptera dominated the diets of these two bat species, both consumed a range of prey items with individual bats having from one to six insect species in their stomachs at the time of death. The prey items identified from eastern red bat fecal pellets showed similar results. A comparison of the turbine insect community to the diet analysis results revealed that the most abundant insects at wind turbines, including terrestrial insects such as crickets and several

  2. Nectar robbing, forager efficiency and seed set: Bumblebees foraging on the self incompatible plant Linaria vulgaris (Scrophulariaceae)

    Science.gov (United States)

    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.

  3. Effects of Grazing Management in Brachiaria grass-forage Peanut Pastures on Canopy Structure and Forage Intake.

    Science.gov (United States)

    Gomes, F K; Oliveira, M D B L; Homem, B G C; Boddey, R M; Bernardes, T F; Gionbelli, M P; Lara, M A S; Casagrande, D R

    2018-06-13

    Maintenance of mixed grass-legume pastures for stand longevity and improved animal utilization is a challenge in warm-season climates. The goal of this study was to assess grazing management on stand persistence, forage intake, and N balance of beef heifers grazing mixed pastures of Brachiaria brizantha and Arachis pintoi. A two-year experiment was carried out in Brazil, where four grazing management were assessed: rest period interrupted at 90%, 95%, and 100% of light interception (LI) and a fixed rest period of 42 days (90LI, 95LI, 100LI, and 42D, respectively). The LI were taken at 50 points at ground level and at five points above the canopy for each paddock using a canopy analyzer. For all treatments, the post-grazing stubble height was 15 cm. Botanical composition and canopy structure characteristics such as canopy height, forage mass, and vertical distribution of the morphological composition were evaluated pre-and post-grazing. Forage chemical composition, intake, and microbial synthesis were also determined. A randomized complete block design was used, considering the season of the year as a repeated measure over time. Grazing management and season were considered fixed, while block and year were considered random effects. In the summer, legume mass accounted for 19% of the canopy at 100LI, which was less than other treatments (a mean of 30%). The 100LI treatment had a greater grass stem mass compared with other treatments. In terms of vertical distribution for 100LI, 38.6% of the stem mass was above the stubble height, greater than the 5.7% for other treatments. The canopy structure limited neutral detergent fiber intake (P = 0.007) at 100LI (1.02% of BW/d), whereas 42D, 90LI, and 95LI treatments had NDF intake close to 1.2% of BW/d. The intake of digestible organic matter (OM; P = 0.007) and the ratio of crude protein/digestible OM (P < 0.001) were less at 100LI in relation to the other treatments. The production of microbial N (P < 0.001) and efficiency

  4. 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

  5. Correlated evolution of herbivory and food chemical discrimination in iguanian and ambush foraging lizards

    OpenAIRE

    William E. Cooper

    2003-01-01

    To efficiently locate and assess foods, animal sensory capacities and behavioral discriminations based on them must be appropriate for the diet and method of hunting. In lizards, actively foraging insectivores identify animal prey using lingually sampled chemical cues, but ambush foragers do not. Among plant eaters derived from active foragers, plant chemical discrimination is added to prey chemical discrimination, resulting in correlated evolution of plant diet and plant chemical discriminat...

  6. 90Sr and 137Cs migration in food chain: soil-forage-cattle

    International Nuclear Information System (INIS)

    Korneev, N.A.; Sirotkin, A.N.

    1982-01-01

    It is established that the coefficients of biological absorption (CBA) of radionuclides by osteal and muscle tissue change with the age of animals. The CBA of strontium-90 and cesium-137 of the grown animals is 3.0 and 2.8 times respectively higher, than of young animals in the migration chain soil-forage, and in the chain forage-bone, and forage-muscles-3.4 and 1.5 times lower

  7. 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.

    2016-01-01

    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. PMID:27069651

  8. A global comparison of the nutritive values of forage plants grown in contrasting environments

    OpenAIRE

    Lee, Mark

    2017-01-01

    Forage plants are valuable because they maintain wild and domesticated herbivores, and sustain the delivery of meat, milk and other commodities. Forage plants contain different quantities of fibre, lignin, minerals and protein, and vary in the proportion of their tissue that can be digested by herbivores. These nutritive components are important determinants of consumer growth rates, reproductive success and behaviour. A dataset was compiled to quantify variation in forage plant nutritive val...

  9. Comparison of Laboratory and Field Remote Sensing Methods to Measure Forage Quality

    OpenAIRE

    Guo, Xulin; Wilmshurst, John F.; Li, Zhaoqin

    2010-01-01

    Recent research in range ecology has emphasized the importance of forage quality as a key indicator of rangeland condition. However, we lack tools to evaluate forage quality at scales appropriate for management. Using canopy reflectance data to measure forage quality has been conducted at both laboratory and field levels separately, but little work has been conducted to evaluate these methods simultaneously. The objective of this study is to find a reliable way of assessing grassland quality ...

  10. 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

  11. Linking foraging behaviour to physical oceanographic structures: Southern elephant seals and mesoscale eddies east of Kerguelen Islands

    Science.gov (United States)

    Dragon, Anne-Cecile; Monestiez, P.; Bar-Hen, A.; Guinet, C.

    2010-10-01

    In the Southern Ocean, mesoscale features, such as fronts and eddies, have been shown to have a significant impact in structuring and enhancing primary productivity. They are therefore likely to influence the spatial structure of prey fields and play a key role in the creation of preferred foraging regions for oceanic top-predators. Optimal foraging theory predicts that predators should adjust their movement behaviour in relation to prey density. While crossing areas with sufficient prey density, we expect predators would change their behaviour by, for instance, decreasing their speed and increasing their turning frequency. Diving predators would as well increase the useful part of their dive i.e. increase bottom-time thereby increasing the fraction of time spent capturing prey. Southern elephant seals from the Kerguelen population have several foraging areas: in Antarctic waters, on the Kerguelen Plateau and in the interfrontal zone between the Subtropical and Polar Fronts. This study investigated how the movement and diving behaviour of 22 seals equipped with satellite-relayed data loggers changed in relation to mesoscale structures typical of the interfrontal zone. We studied the links between oceanographic variables including temperature and sea level anomalies, and diving and movement behaviour such as displacement speed, diving duration and bottom-time. Correlation coefficients between each of the time series were calculated and their significance tested with a parametric bootstrap. We focused on oceanographic changes, both temporal and spatial, occurring during behavioural transitions in order to clarify the connections between the behaviour and the marine environment of the animals. We showed that a majority of seals displayed a specific foraging behaviour related to the presence of both cyclonic and anticyclonic eddies. We characterized mesoscale oceanographic zones as either favourable or unfavourable based on the intensity of foraging activity as

  12. 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.

  13. 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.

  14. 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.

  15. Traplining in bumblebees (Bombus impatiens): a foraging strategy's ontogeny and the importance of spatial reference memory in short-range foraging.

    Science.gov (United States)

    Saleh, Nehal; Chittka, Lars

    2007-04-01

    To test the relative importance of long-term and working spatial memories in short-range foraging in bumblebees, we compared the performance of two groups of bees. One group foraged in a stable array of six flowers for 40 foraging bouts, thereby enabling it to establish a long-term memory of the array, and adjust its spatial movements accordingly. The other group was faced with an array that changed between (but not within) foraging bouts, and thus had only access to a working memory of the flowers that had been visited. Bees in the stable array started out sampling a variety of routes, but their tendency to visit flowers in a repeatable, stable order ("traplining") increased drastically with experience. These bees used shorter routes and converged on four popular paths. However, these routes were mainly formed through linking pairs of flowers by near-neighbour movements, rather than attempting to minimize overall travel distance. Individuals had variations to a primary sequence, where some bees used a major sequence most often, followed by a minor less used route, and others used two different routes with equal frequency. Even though bees foraging in the spatially randomized array had access to both spatial working memory and scent marks, this manipulation greatly disrupted foraging efficiency, mainly via an increase in revisitation to previously emptied flowers and substantially longer search times. Hence, a stable reference frame greatly improves foraging even for bees in relatively small arrays of flowers.

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

    Directory of Open Access Journals (Sweden)

    Vanessa Corby-Harris

    Full Text Available The honey bee is a key pollinator species in decline worldwide. As part of a commercial operation, bee colonies are exposed to a variety of agricultural ecosystems throughout the year and a multitude of environmental variables that may affect the microbial 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. Additionally, several studies hypothesize that the foregut (crop, a key interface between the pollination environment and hive food stores, contains a set of 13 lactic acid bacteria (LAB that inoculate collected pollen and act in synergy to preserve pollen stores. Here, we used a combination of 454 based 16S rRNA gene sequencing of the microbial communities of forager guts, crops, and corbicular pollen and crop plate counts to show that (1 despite a very different diet, forager guts contain a core microbiota similar to that found in younger bees, (2 corbicular pollen contains a diverse community dominated by hive-specific, environmental or phyllosphere bacteria that are not prevalent in the gut or crop, and (3 the 13 LAB found in culture-based studies are not specific to the crop but are a small subset of midgut or hindgut specific bacteria identified in many recent 454 amplicon-based studies. The crop is dominated by Lactobacillus kunkeei, and Alpha 2.2 (Acetobacteraceae, highly osmotolerant and acid resistant bacteria found in stored pollen and honey. Crop taxa at low abundance include core hindgut bacteria in transit to their primary niche, and potential pathogens or food spoilage organisms seemingly vectored from the pollination environment. We conclude that the crop microbial environment is influenced by worker task, and may function in both decontamination and inoculation.

  17. Insulinaemic and glycaemic responses to three forages in ponies.

    Science.gov (United States)

    Carslake, H B; Argo, C McG; Pinchbeck, G L; Dugdale, A H A; McGowan, C M

    2018-05-01

    Reduction of the hyperinsulinaemic response to feeding is central to the management of insulin dysregulation (ID). The aim of this study was to compare insulinaemic and glycaemic responses to soaked hay, dry hay and haylage in ponies. Twelve ponies of mixed breeds were maintained under identical management conditions. A randomised four-way crossover trial was conducted, in which fasted animals were fed a meal of 0.25% body weight as dry matter intake soaked hay, dry hay or haylage, or administered an oral glucose test (OGT). Blood glucose and serum insulin concentrations were measured before and at 2h following OGT, and regularly for 5h following forage meals. Median and interquartile range (IQR) area under the curve (AUC) for insulin (AUC i ) was greater for haylage (median 6495; IQR 17352) vs. dry hay (2932; IQR 5937; P=0.019) and soaked hay (1066; IQR 1753; P=0.002), and greater for dry hay vs. soaked hay (P=0.002). The AUC for glucose (AUC g ) was lower for soaked hay (1021; IQR 99) vs. dry hay (1075; IQR 105; P=0.002) and haylage (1107; IQR 221; P=0.003). Six ponies were classified as having ID based on the OGT. AUC i was greater in ID vs. non-ID ponies after all forages. In contrast, there was no detectable effect of ID status on AUC g . On an equivalent dry matter basis, soaked hay produced the lowest insulinaemic and glycaemic responses to feeding, while haylage produced the highest responses. The insulinaemic effects of all forages were greater in ponies with ID. These data support the practice of soaking hay with water to reduce postprandial insulinaemic responses in ponies. Copyright © 2018 The Authors. Published by 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. IMPLEMENTATION OF DNA MARKERS TO IMPROVE BREEDING OF FORAGE LEGUMES

    Directory of Open Access Journals (Sweden)

    S. Grljušić

    2008-09-01

    Full Text Available The low rates of estimated genetic gains in forage legumes breeding have emphasized the need for new breeding methods that would increase efficiency in forage selection and provide reliable improvement. Information on application of molecular methodologies and tools for the enhancement of the current empirical phenotype-based selection moved us toward implementation of DNA markers to our breeding activities. Firstly, attention was given to identification of genetic variability within the forage species involved in program and comparison of conventional and molecular marker efficiency in variability evaluation. RAPDs were used (i to estimate availability of alfalfa (Medicago sativa L. and Medicago falcata L. genetic variation and (ii to identify changes of red clover (Trifolium pratense L. variability after natural selection. SSRs were applied to evaluate diversity within and among field pea (Pisum sativum L. var. arvense and sativum groups/varieties. A total of 90 (alfalfa or 92 (red clover polymorphic bands was found by RAPDs. Total number of SSR alleles recorded was 118. The average Roger's distance per species/genus estimated was 0.29 (red clover, 0.33 (alfalfa and 0.51 (field pea. 2D PCo analysis of each species/genus separated materials into respective groups. A high degree of genetic variation within populations/varieties of each investigated species was found by AMOVA. The correspondence between pairs of matrices based on the morphological and molecular data was significant (p=0.95 only for red clover. RAPD and SSR data have given valuable information on genetic structure of materials and provided a description that determines heterogeneity. Further studies will be focused on identifying quantitative trait loci and marker assisted selection.

  20. 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.

  1. 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...

  2. Synergy in spreading processes: from exploitative to explorative foraging strategies.

    Science.gov (United States)

    Pérez-Reche, Francisco J; Ludlam, Jonathan J; Taraskin, Sergei N; Gilligan, Christopher A

    2011-05-27

    An epidemiological model which incorporates synergistic effects that allow the infectivity and/or susceptibility of hosts to be dependent on the number of infected neighbors is proposed. Constructive synergy induces an exploitative behavior which results in a rapid invasion that infects a large number of hosts. Interfering synergy leads to a slower and sparser explorative foraging strategy that traverses larger distances by infecting fewer hosts. The model can be mapped to a dynamical bond percolation with spatial correlations that affect the mechanism of spread but do not influence the critical behavior of epidemics. © 2011 American Physical Society

  3. Has eutrophication promoted forage fish production in the Baltic Sea?

    DEFF Research Database (Denmark)

    Eero, Margit; Andersson, Helén C; Almroth-Rosell, Elin

    2016-01-01

    Reducing anthropogenic nutrient inputs is a major policy goal for restoring good environmental status of coastal marine ecosystems. However, it is unclear to what extent reducing nutrients would also lower fish production and fisheries yields. Empirical examples of changes in nutrient loads...... and concurrent fish production can provide useful insights to this question. In this paper, we investigate to what extent a multi-fold increase in nutrient loads from the 1950s to 1980s enhanced forage fish production in the Baltic Sea. We use monitoring data on fish stock dynamics covering the period...

  4. 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.

  5. Characterization of the core rumen microbiome in cattle during transition from forage to concentrate as well as during and after an acidotic challenge.

    Science.gov (United States)

    Petri, Renee M; Schwaiger, Tyler; Penner, Greg B; Beauchemin, Karen A; Forster, Robert J; McKinnon, John J; McAllister, Tim A

    2013-01-01

    This study investigated the effect of diet and host on the rumen bacterial microbiome and the impact of an acidotic challenge on its composition. Using parallel pyrosequencing of the V3 hypervariable region of 16S rRNA gene, solid and liquid associated bacterial communities of 8 heifers were profiled. Heifers were exclusively fed forage, before being transitioned to a concentrate diet, subjected to an acidotic challenge and allowed to recover. Samples of rumen digesta were collected when heifers were fed forage, mixed forage, high grain, during challenge (4 h and 12 h) and recovery. A total of 560,994 high-quality bacterial sequences were obtained from the solid and liquid digesta. Using cluster analysis, prominent bacterial populations differed (P≤0.10) in solid and liquid fractions between forage and grain diets. Differences among hosts and diets were not revealed by DGGE, but real time qPCR showed that several bacteria taxon were impacted by changes in diet, with the exception of Streptococcus bovis. Analysis of the core rumen microbiome identified 32 OTU's representing 10 distinct bacterial taxa including Bacteroidetes (32.8%), Firmicutes (43.2%) and Proteobacteria (14.3%). Diversity of OTUs was highest with forage with 38 unique OTUs identified as compared to only 11 with the high grain diet. Comparison of the microbial profiles of clincial vs. subclinical acidotic heifers found a increases in the relative abundances of Acetitomaculum, Lactobacillus, Prevotella, and Streptococcus. Increases in Streptococcus and Lactobacillus likely reflect the tolerance of these species to low pH and their ability to proliferate on surplus fermentable carbohydrate. The acetogen, Acetitomaculum may thereforeplay a role in the conversion of lactate to acetate in acidotic animals. Further profiling of the bacterial populations associated with subclinical and clinical acidosis could establish a microbial fingerprint for these disorders and provide insight into whether there are

  6. Magnitude differences in agronomic, chemical, nutritional, and structural features among different varieties of forage corn grown on dry land and irrigated land.

    Science.gov (United States)

    Xin, Hangshu; Abeysekara, Samen; Zhang, Xuewei; Yu, Peiqiang

    2015-03-11

    In this study, eight varieties of corn forage grown in semiarid western Canada (including Pioneer P2501, Pioneer P39m26, Pioneer P7443, Hyland HL3085, Hyland HLBaxxos, Hyland HLR219, Hyland HLSR22, and Pickseed Silex BT) were selected to explore the effect of irrigation implementation in comparison with nonirrigation on (1) agronomic characteristics, (2) basic chemical profiles explored by using a near-infrared reflectance (NIR) system, and (3) protein and carbohydrate internal structural parameters revealed by using an attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) system. Also, principal component analysis (PCA) was performed on spectroscopic data for clarification of differences in molecular structural makeup among the varieties. The results showed that irrigation treatment significantly increased (P forages. Significant interactions of irrigation treatment and corn variety were observed on most agronomic characteristics (DM yield, T/ha, days to tasseling, days to silking) and crude fiber (CF) and ether extract (EE) contents as well as some spectral data such as cellulosic compounds (CELC) peak intensity, peak ratios of CHO third peak to CELC, α-helix to β-sheet, and CHO third peak to amide I. Additionally, the spectral ratios of chemical functional groups that related to structural and nonstructural carbohydrates and protein polymers in forages did not remain constant over corn varieties cultivated with and without water treatment. Moreover, different cultivars had different growth, structure, and nutrition performances in this study. Although significant differences could be found in peak intensities, PCA results indicated some structural similarities existed between two treated corn forages with the exception of HL3085 and HLBaxxos. In conclusion, irrigation and corn variety had interaction effects on agronomic, chemical, nutritional, and structural features. Further study on the optimum level of irrigation for corn forage

  7. Increase of forage dryness induces differentiated anatomical response in the sheep rumen compartments.

    Science.gov (United States)

    Scocco, Paola; Mercati, Francesca; Tardella, Federico Maria; Catorci, Andrea

    2016-08-01

    The aim of this study was to investigate how the Surface Enlargement Factor (SEF) and the epithelial keratinization degree of sheep rumen change in response to phytomass production, and to forage fiber and water content during the pasture vegetative cycle. The study used eighteen sheep nourished with dry hay and cereals during the winter season and with fresh hay during the pasture vegetative cycle. We collected samples from rumen indicative regions for two consecutive years characterized by different rainfall and pasture productivity values. We evaluated the densities (D) of rumen papillae to estimate the rumen SEF, and the keratinization percentage of the epithelial lining; these parameters showed differentiated modifications in the four ruminal analyzed compartments in response to pasture seasonal conditions. In addition, we performed Canonical Redundancy Analysis (RDA) on the "keratinization and SEF" matrix constrained by phytomass, water, and crude fiber contents of pasture at different time in the two considered years to highlight how rumen features answer to pasture conditions. Atrium (A) and ventral sac (VS) keratinization showed a strict positive correlation to crude fiber, while SEF of VS was positively related to phytomass and forage water content. The degree of keratinization of the rumen VS epithelium proved to be a useful parameter for evaluating anatomical variations in the short term period related to pasture features; in addition, its monitoring could be carried out through biopsy, thus avoiding the killing of animals. The study also leads to the application of the 3Rs (Replacement; Reduction; and Refinement). Microsc. Res. Tech. 79:738-743, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Climatic and hydrologic influences on wading bird foraging patterns in Everglades National Park

    Science.gov (United States)

    Kwon, H.; Lall, U.; Engel, V.

    2007-12-01

    A goal of the Everglades National Park (ENP) restoration project is to ensure that the ecological health of the ENP improves as a direct result of management activities. Achieving hydrologic targets through the proper timing and amount of releases from control structures is a first step in the management process. Significant climate and weather variations in the region influence the ability to make releases and also determine the ecological outcomes. An assessment of the relative impact of climate variations and water releases to ENP in determining ecological outcomes is consequently a key to the evaluation of the success or failure of any restoration plan. Seasonal water depths in ENP depend on managed surface water releases from control structures and on direct rainfall. Here we link wading bird foraging patterns - a fundamental aspect of Everglades' ecology - to hydrologic management and climate variability in the National Park. Our objective is multifold. First, we relate the water levels at P33 and Shark Slough to the synoptic hydrologic conditions. Second, we develop a statistical model relating water levels at a station in central Shark Slough (P33) to wading birds foraging patterns throughout ENP. We attempt to apply a Hierarchical Bayesian scheme to a time series of wading bird to provide an uncertainty distribution of the population over specified time periods given hydrologic condition. Third, we develop a set of hydrologic index derived by recorded water level at P33 for a use of the statistical model of wading birds as an input. Our study will focus on great egret and white ibis that are major species among wading birds in the ENP. The great egret and white ibis prediction predicted by the model using the proposed predictors exhibits strong correlation with the observed streamflow, with an correlation 0.8.

  9. Digestibility and performance of juvenile Nile tilapia fed with diets containing forage palm

    Directory of Open Access Journals (Sweden)

    Hannah Bandeira Thame Daniel

    2016-09-01

    Full Text Available Supplying the nutritional needs of animals in an economical way is essential to the success of any type of production. The forage palm is a cactaceae well-adapted to semiarid regions and commonly used in the feeding of ruminants. However, studies assessing its use in fishes are scarce. We aimed to evaluate the digestibility of bran from five different forage palm cultivars (Opuntia fícus in juvenile Nile tilapia and the development of juveniles when receiving increasing levels of the cultivar with the best apparent digestibility coefficient of crude protein (ADCCP (75.2%. We used 90 masculinized juvenile Nile tilapia (with an average weight of 6.02 ± 0.65 g in the digestibility experiment to determine the apparent digestibility coefficients of dry matter (ADCDM, crude energy (ADCCP, and crude protein of the cultivars (Orelha de onça, Miúda, Gigante, Comum, and IPA 20. The experimental design was completely randomized (CRD with five treatments and three repetitions. In the development experiment, 300 masculinized juvenile Nile tilapia (with average weight of 1.39 ± 0.12 g received feed with different inclusion levels (0, 72, 144, and 216 g Kg-1 of IPA 20 palm bran in a CRD with four treatments and five repetitions. We observed significant differences (P < 0.05 for ADCDM and ADCCP between the treatments. The cultivars that presented the highest ADCDM were IPA 20 (41.75%, Orelha de onça (36.41%, and Gigante (32.59%. For ADCCP, the best cultivar was IPA 20 with 75.2%, followed by Orelha de onça (61.5%, and Miúda (56.1%. As for the performance, the inclusion of IPA 20 palm bran at a rate of 113 g/kg-1 provided the best values in terms of weight gain and final weight in juvenile Nile tilapia.

  10. 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.

  11. 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

  12. Mapping Forage Resources Using Earth Observation Data: A Case Study to Assess the Relationship Between Herbaceous and Woody Cover Components as Determinants of Large Herbivore Distribution in Sub-Saharan Africa

    Science.gov (United States)

    Hanan, N. P.; Kahiu, M. N.

    2016-12-01

    Grazing systems are important for survival of humans, livestock and wildlife in Sub-Saharan Africa (SSA). They are mainly found in the arid and semi-arid regions and are characterized by naturally occurring tree-grass vegetation mixtures ("savannas"), low and erratic rainfall, low human populations, and scanty water resources. Due to the scarce population and perceived low resource base they have been marginalized for decades, if not centuries. However, their economic and environmental significance, particularly their role as foraging lands for livestock and wildlife cannot be underrated. SSA natural grazing systems comprise a significant source of livelihood, where millions of people depend on pastoralism as a source of food and income. Further, the African savannas support diverse flora and charismatic large herbivore and carnivore guilds. The above considerations motivate a more detailed study of the composition, temporal and spatial variability of foraging resources in SSA arid and semi-arid regions. We have therefore embarked on a research to map Africa foraging resources by partitioning MODIS total leaf area index (LAIA) time series into its woody (LAIW) and herbaceous (LAIH) constituents as proxies for grazing and browsing resources, respectively. Using the portioned LAI estimates we will develop a case study to assess how forage resources affect distribution and abundance of large herbivores in Africa. In our case study we explore two separate but related hypothesis: i) small and medium sized mammalian herbivore numbers will peak at intermediate biomass (LAIH for grazers and LAIW for browsers), since they optimize on forage quantity and quality. Conversely, large-body mammalian herbivores have the ability to process high quantity-low quality food, hence, we hypothesize that ii) larger herbivores will tend to be more common in high forage areas irrespective of forage quality. We will use LAIH and LAIW retrievals to compute annual average leaf area duration

  13. Vortex Formation and Foraging in Polyphenic Spadefoot Toad Tadpoles.

    Science.gov (United States)

    Bazazi, Sepideh; Pfennig, Karin S; Handegard, Nils Olav; Couzin, Iain D

    2012-06-01

    Animal aggregations are widespread in nature and can exhibit complex emergent properties not found at an individual level. We investigate one such example here, collective vortex formation by congeneric spadefoot toad tadpoles: Spea bombifrons and S. multiplicata. Tadpoles of these species develop into either an omnivorous or a carnivorous (cannibalistic) morph depending on diet. Previous studies show S. multiplicata are more likely to develop into omnivores and feed on suspended organic matter in the water body. The omnivorous morph is frequently social, forming aggregates that move and forage together, and form vortices in which they adopt a distinctive slowly-rotating circular formation. This behaviour has been speculated to act as a means to agitate the substratum in ponds and thus could be a collective foraging strategy. Here we perform a quantitative investigation of the behaviour of tadpoles within aggregates. We found that only S. multiplicata groups exhibited vortex formation, suggesting that social interactions differ between species. The probability of collectively forming a vortex, in response to introduced food particles, increased for higher tadpole densities and when tadpoles were hungry. Individuals inside a vortex moved faster and exhibited higher (by approximately 27%) tailbeat frequencies than those outside the vortex, thus incurring a personal energetic cost. The resulting environmental modification, however, suggests vortex behaviour may be an adaptation to actively create, and exploit, a resource patch within the environment.

  14. Testing optimal foraging theory in a penguin-krill system.

    Science.gov (United States)

    Watanabe, Yuuki Y; Ito, Motohiro; Takahashi, Akinori

    2014-03-22

    Food is heterogeneously distributed in nature, and understanding how animals search for and exploit food patches is a fundamental challenge in ecology. The classic marginal value theorem (MVT) formulates optimal patch residence time in response to patch quality. The MVT was generally proved in controlled animal experiments; however, owing to the technical difficulties in recording foraging behaviour in the wild, it has been inadequately examined in natural predator-prey systems, especially those in the three-dimensional marine environment. Using animal-borne accelerometers and video cameras, we collected a rare dataset in which the behaviour of a marine predator (penguin) was recorded simultaneously with the capture timings of mobile, patchily distributed prey (krill). We provide qualitative support for the MVT by showing that (i) krill capture rate diminished with time in each dive, as assumed in the MVT, and (ii) dive duration (or patch residence time, controlled for dive depth) increased with short-term, dive-scale krill capture rate, but decreased with long-term, bout-scale krill capture rate, as predicted from the MVT. Our results demonstrate that a single environmental factor (i.e. patch quality) can have opposite effects on animal behaviour depending on the time scale, emphasizing the importance of multi-scale approaches in understanding complex foraging strategies.

  15. Role of depletion on the dynamics of a diffusing forager

    International Nuclear Information System (INIS)

    Bénichou, O; Chupeau, M; Redner, S

    2016-01-01

    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. (paper)

  16. 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.

  17. 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.

  18. 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. PMID:26288228

  19. Forage Options for Dairy Farms with Reduced Water Availability in the Southern Murray Darling Basin of Australia

    Directory of Open Access Journals (Sweden)

    Mary-Jane Rogers

    2017-12-01

    Full Text Available The dairy industry in the southern Murray Darling Basin region of Australia is a major consumer of irrigation water because rainfall is low relative to evapotranspiration and the industrys relies heavily on irrigated temperate pastures and fodder crops. Water reforms, and potential climate change scenarios for this region suggest that there will be an overall decline in rainfall and water available for irrigation in the future. For the irrigated dairy industry to remain economically viable, there is a need for dairy farmers to improve the water productivity (WP of their forage systems and to be able to respond to year-to-year, and within year, variation in water availability. Researchers and dairy farmers are evaluating strategies to increase WP. These include: (i selecting better-adapted species for current and predicted climatic conditions; (ii using species that can survive and still be productive under reduced irrigation and then recover when full irrigation is restored; (iii modifying irrigation strategies to reduce water use whilst maintaining WP; and (iv grazing management strategies that facilitate the survival during, and recovery after, periods of moisture stress. This review will examine these strategies and discusses their potential to optimise forage production from irrigation water inputs so that the dairy industry in the southern Murray Darling Basin remains viable in the future.

  20. Effects of plant density on forage production in five populations of ...

    African Journals Online (AJOL)

    Kleingrass (Panicum coloratum L.) forage yield evaluation plots are often established at a density of 6.0 plants m-2 to accommodate mechanical transplanting and harvesting equipment. However, forage crops are usually established from seed at higher plant densities. Experiments were conducted to determine if ...

  1. 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.

  2. Resource diversity and landscape-level homogeneity drive native bee foraging.

    Science.gov (United States)

    Jha, Shalene; Kremen, Claire

    2013-01-08

    Given widespread declines in pollinator communities and increasing global reliance on pollinator-dependent crops, there is an acute need to develop a mechanistic understanding of native pollinator population and foraging biology. Using a population genetics approach, we determine the impact of habitat and floral resource distributions on nesting and foraging patterns of a critical native pollinator, Bombus vosnesenskii. Our findings demonstrate that native bee foraging is far more plastic and extensive than previously believed and does not follow a simple optimal foraging strategy. Rather, bumble bees forage further in pursuit of species-rich floral patches and in landscapes where patch-to-patch variation in floral resources is less, regardless of habitat composition. Thus, our results reveal extreme foraging plasticity and demonstrate that floral diversity, not density, drives bee foraging distance. Furthermore, we find a negative impact of paved habitat and a positive impact of natural woodland on bumble bee nesting densities. Overall, this study reveals that natural and human-altered landscapes can be managed for increased native bee nesting and extended foraging, dually enhancing biodiversity and the spatial extent of pollination services.

  3. 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...

  4. To walk or to fly? How birds choose among foraging modes

    NARCIS (Netherlands)

    Bautista, LM; Tinbergen, J; Kacelnik, A; Bautista, Luis M.; Southwood, Richard

    2001-01-01

    We test the predictive value of the main energetic currencies used in foraging theory using starlings that choose between two foraging modes (walking versus flying). Walking is low-cost, low-yield, whereas flying is the opposite. We fixed experimentally, at 11 different values, the amount of flight

  5. Winter active bumblebees (Bombus terrestris achieve high foraging rates in urban Britain.

    Directory of Open Access Journals (Sweden)

    Ralph J Stelzer

    2010-03-01

    Full Text Available Foraging bumblebees are normally associated with spring and summer in northern Europe. However, there have been sightings of the bumblebee Bombus terrestris during the warmer winters in recent years in southern England. But what floral resources are they relying upon during winter and how much winter forage can they collect?To test if urban areas in the UK provide a rich foraging niche for bees we set up colonies of B. terrestris in the field during two late winter periods (2005/6 & 2006/7 in London, UK, and measured their foraging performance. Fully automatic radio-frequency identification (RFID technology was used in 2006/7 to enable us to record the complete foraging activity of individually tagged bees. The number of bumblebees present during winter (October 2007 to March 2008 and the main plants they visited were also recorded during transect walks. Queens and workers were observed throughout the winter, suggesting a second generation of bee colonies active during the winter months. Mass flowering shrubs such as Mahonia spp. were identified as important food resources. The foraging experiments showed that bees active during the winter can attain nectar and pollen foraging rates that match, and even surpass, those recorded during summer.B. terrestris in the UK are now able to utilise a rich winter foraging resource in urban parks and gardens that might at present still be under-exploited, opening up the possibility of further changes in pollinator phenology.

  6. Winter active bumblebees (Bombus terrestris) achieve high foraging rates in urban Britain.

    Science.gov (United States)

    Stelzer, Ralph J; Chittka, Lars; Carlton, Marc; Ings, Thomas C

    2010-03-05

    Foraging bumblebees are normally associated with spring and summer in northern Europe. However, there have been sightings of the bumblebee Bombus terrestris during the warmer winters in recent years in southern England. But what floral resources are they relying upon during winter and how much winter forage can they collect? To test if urban areas in the UK provide a rich foraging niche for bees we set up colonies of B. terrestris in the field during two late winter periods (2005/6 & 2006/7) in London, UK, and measured their foraging performance. Fully automatic radio-frequency identification (RFID) technology was used in 2006/7 to enable us to record the complete foraging activity of individually tagged bees. The number of bumblebees present during winter (October 2007 to March 2008) and the main plants they visited were also recorded during transect walks. Queens and workers were observed throughout the winter, suggesting a second generation of bee colonies active during the winter months. Mass flowering shrubs such as Mahonia spp. were identified as important food resources. The foraging experiments showed that bees active during the winter can attain nectar and pollen foraging rates that match, and even surpass, those recorded during summer. B. terrestris in the UK are now able to utilise a rich winter foraging resource in urban parks and gardens that might at present still be under-exploited, opening up the possibility of further changes in pollinator phenology.

  7. Ovary activation does not correlate with pollen and nectar foraging specialization in the bumblebee Bombus impatiens

    Directory of Open Access Journals (Sweden)

    Meagan A. Simons

    2018-02-01

    Full Text Available Social insect foragers may specialize on certain resource types. Specialization on pollen or nectar among honeybee foragers is hypothesized to result from associations between reproductive physiology and sensory tuning that evolved in ancestral solitary bees (the Reproductive Ground-Plan Hypothesis; RGPH. However, the two non-honeybee species studied showed no association between specialization and ovary activation. Here we investigate the bumblebee B. impatiens because it has the most extensively studied pollen/nectar specialization of any bumblebee. We show that ovary size does not differ between pollen specialist, nectar specialist, and generalist foragers, contrary to the predictions of the RGPH. However, we also found mixed support for the second prediction of the RGPH, that sensory sensitivity, measured through proboscis extension response (PER, is greater among pollen foragers. We also found a correlation between foraging activity and ovary size, and foraging activity and relative nectar preference, but no correlation between ovary size and nectar preference. In one colony non-foragers had larger ovaries than foragers, supporting the reproductive conflict and work hypothesis, but in the other colony they did not.

  8. Gathering Baltimore's bounty: Characterizing behaviors, motivations, and barriers of foragers in an urban ecosystem

    Science.gov (United States)

    Colleen M. Synk; Brent F. Kim; Charles A. Davis; James Harding; Virginia Rogers; Patrick T. Hurley; Marla R. Emery; Keeve E. Nachman

    2017-01-01

    As a component of urban food systems, foraging—the collection of plant or fungal materials, such as berries and nuts, not deliberately cultivated for human use—may promote positive cultural, ecological, economic, and health outcomes. Foraging behaviors, motivations, and barriers in the urban context remain under-characterized despite emerging literature on the subject...

  9. Variability of indigestible NDF in C 3 and C 4 forages and ...

    African Journals Online (AJOL)

    The relationship between iNDF and acid detergent lignin (ADL) is more variable, across and within forage species. The purpose of our study was then to assess the variability of iNDF and respective implications on ration fine-tuning for dairy cattle. Sixty forages, including grasses, maize silages and lucerne hays, were ...

  10. 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

  11. To walk or to fly? How birds choose among foraging modes

    Science.gov (United States)

    Bautista, Luis M.; Tinbergen, Joost; Kacelnik, Alejandro

    2001-01-01

    We test the predictive value of the main energetic currencies used in foraging theory using starlings that choose between two foraging modes (walking versus flying). Walking is low-cost, low-yield, whereas flying is the opposite. We fixed experimentally, at 11 different values, the amount of flight required to get one food reward, and for each flight cost value, we titrated the amount of walking until the birds showed indifference between foraging modes. We then compared the indifference points to those predicted by gross rate of gain over time, net rate of gain over time, and the ratio of gain to expenditure (efficiency). The results for the choice between modes show strong qualitative and quantitative support for net rate of gain over time over the alternatives. However, the birds foraged for only a fraction of the available time, indicating that the choice between foraging and resting could not be explained by any of these currencies. We suggest that this discrepancy could be accounted for functionally because nonenergetic factors such as predation risk may differ between resting and foraging in any mode but may not differ much between foraging modes, hence releasing the choice between foraging modes from the influence of such factors. Alternatively, the discrepancy may be attributable to the use of predictable (rather than stochastic) ratios of effort per prey in our experiment, and it may thus be better understood with mechanistic rather than functional arguments. PMID:11158599

  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. FEEDING BROWN MIDRIB FORAGE SORGHUM SILAGE AND CORN GLUTEN FEED TO LACTATING DAIRY COWS

    Science.gov (United States)

    Brown midrib (BMR) forage sorghum contains less lignin , resulting in increased NDF digestibility compared to conventional sorghum . An experiment was conducted to evaluate the effects of BMR forage sorghum silage in diets containing wet corn gluten feed (WCGF). The objective was to determine the e...

  14. Effect of Grazing on Forage Quality and Quantity for Ungulates of ...

    African Journals Online (AJOL)

    This study examined the effect of grazing as simulated by clipping on forage quality and quantity in terms of above ground biomass, live, total production and nutrients content of forages utilized by ungulates of Kainji Lake National Park. Three 2.5m by 2.5m plots were constructed in the three main vegetation communities in ...

  15. Foraging site choice and diet selection of Meadow Pipits Anthus pratensis breeding on grazed salt marshes

    NARCIS (Netherlands)

    van Klink, Roel; Mandema, Freek S.; Bakker, Jan P.; Tinbergen, Joost M.

    2014-01-01

    Capsule Breeding Meadow Pipits foraged for caterpillars and large spiders in vegetation that was less heterogeneous than vegetation at random locations.Aims To gain a better understanding of the foraging ecology of breeding Meadow Pipits on grazed coastal salt marshes, we tested three hypotheses:

  16. 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...

  17. The influence of daily variation in foraging cost on the activity of small carnivores

    Science.gov (United States)

    William J. Zielinski

    1988-01-01

    The daily activity of some predators is correlated with the activity pattern of their prey. If capture efficiency varies as a function of prey activity, a predator that synchronizes its foraging activity with the time of day that prey are most vulnerable should capture more prey, and at lower cost, than a predator that initiates foraging at random. Mink, ...

  18. Seasonal nutrient yield and digestibility of deer forage from a young pine plantation

    Science.gov (United States)

    Robert M. Blair; Henry L. Short; E.A. Epps

    1977-01-01

    Six classes of current herbaceous and woody forage were collected seasonally from a 5-year-old mixed loblolly (Pinus taeda)-shortleaf pine (Pinus echinata) plantation (in Texas) and subjected to nutrient analyses and nylon bag dry-matter digestion trials. Forages were most nutritious and digestible in the spring when tissues were succulent and growing rapidly. Browse...

  19. Forage accumulation and nutritive value of reduced lignin and reference alfalfa cultivars

    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 ...

  20. Genetic diversity within honeybee colonies increases signal production by waggle-dancing foragers

    Science.gov (United States)

    Mattila, Heather R; Burke, Kelly M; Seeley, Thomas D

    2008-01-01

    Recent work has demonstrated considerable benefits of intracolonial genetic diversity for the productivity of honeybee colonies: single-patriline colonies have depressed foraging rates, smaller food stores and slower weight gain relative to multiple-patriline colonies. We explored whether differences in the use of foraging-related communication behaviour (waggle dances and shaking signals) underlie differences in foraging effort of genetically diverse and genetically uniform colonies. We created three pairs of colonies; each pair had one colony headed by a multiply mated queen (inseminated by 15 drones) and one colony headed by a singly mated queen. For each pair, we monitored the production of foraging-related signals over the course of 3 days. Foragers in genetically diverse colonies had substantially more information available to them about food resources than foragers in uniform colonies. On average, in genetically diverse colonies compared with genetically uniform colonies, 36% more waggle dances were identified daily, dancers performed 62% more waggle runs per dance, foragers reported food discoveries that were farther from the nest and 91% more shaking signals were exchanged among workers each morning prior to foraging. Extreme polyandry by honeybee queens enhances the production of worker–worker communication signals that facilitate the swift discovery and exploitation of food resources. PMID:18198143

  1. Depiction of Wild Food Foraging Practices in the Media: Impact of the Great Recession

    Science.gov (United States)

    Sonya Sachdeva; Marla R. Emery; Patrick T. Hurley

    2018-01-01

    The practice of gathering and harvesting wild foods has seen renewed interest in recent decades. In addition to contributing to food security and food sovereignty, foraging plays a role in promoting socioecological resilience and creating communities of belonging. However, foraging is generally prohibited by regulations governing public lands in the United States and...

  2. Urban foraging: a ubiquitous human practice overlooked by urban planners, policy, and research

    Science.gov (United States)

    Charlie Shackleton; Patrick Hurley; Annika Dahlberg; Marla Emery; Harini. Nagendra

    2017-01-01

    Although hardly noticed or formally recognised, urban foraging by humans probably occurs in all urban settings around the world. We draw from research in India, South Africa, Sweden, and the United States to demonstrate the ubiquity and varied nature of urban foraging in different contexts. Across these different contexts, we distil seven themes that characterise and...

  3. Changes in learning and foraging behaviour within developing bumble bee (Bombus terrestris colonies.

    Directory of Open Access Journals (Sweden)

    Lisa J Evans

    Full Text Available Organisation in eusocial insect colonies emerges from the decisions and actions of its individual members. In turn, these decisions and actions are influenced by the individual's behaviour (or temperament. Although there is variation in the behaviour of individuals within a colony, we know surprisingly little about how (or indeed if the types of behaviour present in a colony change over time. Here, for the first time, we assessed potential changes in the behavioural type of foragers during colony development. Using an ecologically relevant foraging task, we measured the decision speed and learning ability of bumble bees (Bombus terrestris at different stages of colony development. We determined whether individuals that forage early in the colony life cycle (the queen and early emerging workers behaved differently from workers that emerge and forage at the end of colony development. Whilst we found no overall change in the foraging behaviour of workers with colony development, there were strong differences in foraging behaviour between queens and their workers. Queens appeared to forage more cautiously than their workers and were also quicker to learn. These behaviours could allow queens to maximise their nectar collecting efficiency whilst avoiding predation. Because the foundress queen is crucial to the survival and success of a bumble bee colony, more efficient foraging behaviour in queens may have strong adaptive value.

  4. Do inter-colony differences in Cape fur seal foraging behaviour ...

    African Journals Online (AJOL)

    We investigated how such environmental variability may impact foraging behaviour of the Cape fur seal Arctocephalus pusillus pusillus, using satellite telemetry on animals in northern, central and southern Namibia. We expected that seal foraging behaviour would reflect a gradient of deteriorating feeding conditions from ...

  5. Nutritional composition of a full diallel-crossed forage pearl millet of ...

    African Journals Online (AJOL)

    The productivity of local cattle depends mainly on the quality of forage they consume, the search of which induces conflicts between herdsmen and farmers. The objective of this study was to evaluate the nutritional quality of 'maiwa' Pennisetum glaucum, for forage, in Ibadan, Nigeria. Three inbred lines, namely, 25-2, 28-1 ...

  6. The energetic importance of night foraging for waders wintering in a temperate estuary

    NARCIS (Netherlands)

    Lourenco, Pedro M.; Silva, Andreia; Santos, Carlos D.; Miranda, Ana C.; Granadeiro, Jose P.; Palmeirim, Jorge M.

    2008-01-01

    Many species of waders forage extensively at night, but there is very little information on the relevance of this behaviour for the energy budget of waders wintering in estuarine wetlands. Quantitative data on diurnal and nocturnal intake rates can indicate the extent to which birds need to forage

  7. Avoiding competition? Site use, diet and foraging behaviours in two similarly sized geese wintering in China

    DEFF Research Database (Denmark)

    Zhao, Meijuan; Cao, Lei; Klaassen, Marcel

    2015-01-01

    at Shengjin Lake, China. To examine the potential for coexistence and possible avoidance strategies, we studied (1) their habitat use, (2) foraging behaviours and (3) diets of birds foraging in mixed- and single-species flocks. Both species extensively exploited sedge meadows, where they showed considerable...

  8. Selection on feather pecking affects response to novelty and foraging behaviour in laying hens

    NARCIS (Netherlands)

    Haas, de E.N.; Nielsen, B.; Rodenburg, T.B.; Buitenhuis, A.J.

    2010-01-01

    Feather pecking (FP) is a major welfare problem in laying hens, influenced by multiple factors. FP is thought to be redirected foraging behaviour, however fearful birds are also known to be more sensitive to develop FP. The relationship between fear-responses, foraging and FP is not well understood,

  9. Maize stubble as foraging habitat to wintering geese and swans in northern Europe.

    NARCIS (Netherlands)

    Clausen, K.K.; Madsen, J.; Nolet, B.A.; Haugaard, L.

    2018-01-01

    Agricultural crops have become increasingly important foraging habitats to geese and swans in northern Europe, and a recent climate-driven expansion in the area of maize fields has led to a rapid increase in the exploitation of this habitat. However, due to the novelty of maize foraging in this

  10. Foraging behavior of stingless bee Heterotrigona itama (Cockerell, 1918) (Hymenoptera : Apidae : Meliponini)

    Science.gov (United States)

    Jaapar, Mohd Fahimee; Jajuli, Rosliza; Mispan, Muhamad Radzali; Ghani, Idris Abd

    2018-04-01

    A study to investigate the foraging behavior of Heterotrigona itama (Cockerell, 1918) was conducted on three colonies between January 2016 and June 2016. A digital single-lens reflex (DSLR) with macro lens attached, and action camera (SJCAM) was used to record foraging behavior of H. itama in its colonies for 5 min per hour between 0800 to 1700 h for a day per 6 months. In addition, three data loggers (Watchdog B100 2K) has been installed adjacent to the observation nest for collect temperature and humidity in the study areas. Result showed that the numbers of return foragers was significantly different from January to June also with outgoing forager. The returning forager between hours showed significant different from 8 am to 5 pm also for outgoing forager. The ideal temperature related to foraging behavior for H. itama was 29°C to 32 °C Our finding also, helps to guide researcher to expand the knowledge in foraging behavior by stingless bee as well as encouraging more small farmers to start rearing at least for their own consumption. In addition, these findings also guide the farmers to manage their chemical toxic inside the meliponiculture.

  11. Ovary activation does not correlate with pollen and nectar foraging specialization in the bumblebee Bombus impatiens.

    Science.gov (United States)

    Simons, Meagan A; Smith, Adam R

    2018-01-01

    Social insect foragers may specialize on certain resource types. Specialization on pollen or nectar among honeybee foragers is hypothesized to result from associations between reproductive physiology and sensory tuning that evolved in ancestral solitary bees (the Reproductive Ground-Plan Hypothesis; RGPH). However, the two non-honeybee species studied showed no association between specialization and ovary activation. Here we investigate the bumblebee B. impatiens because it has the most extensively studied pollen/nectar specialization of any bumblebee. We show that ovary size does not differ between pollen specialist, nectar specialist, and generalist foragers, contrary to the predictions of the RGPH. However, we also found mixed support for the second prediction of the RGPH, that sensory sensitivity, measured through proboscis extension response (PER), is greater among pollen foragers. We also found a correlation between foraging activity and ovary size, and foraging activity and relative nectar preference, but no correlation between ovary size and nectar preference. In one colony non-foragers had larger ovaries than foragers, supporting the reproductive conflict and work hypothesis, but in the other colony they did not.

  12. Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

    OpenAIRE

    Barro,Raquel Santiago; Varella,Alexandre Costa; Lemaire,Gilles; Medeiros,Renato Borges de; Saibro,João Carlos de; Nabinger,Carlos; Bangel,Felipe Villamil; Carassai,Igor Justin

    2012-01-01

    The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY) and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum) and a forage legume (Arachis pintoi) under two shading levels compared with...

  13. Persistence of forage fish ‘hot spots’ and its association with foraging Steller sea lions (Eumetopias jubatus) in southeast Alaska

    Science.gov (United States)

    Gende, Scott M.; Sigler, Michael F.

    2006-02-01

    Whereas primary and secondary productivity at oceanic 'hotspots' may be a function of upwelling and temperature fronts, the aggregation of higher-order vertebrates is a function of their ability to search for and locate these areas. Thus, understanding how predators aggregate at these productive foraging areas is germane to the study of oceanic hot spots. We examined the spatial distribution of forage fish in southeast Alaska for three years to better understand Steller sea lion ( Eumetopias jubatus) aggregations and foraging behavior. Energy densities (millions KJ/km 2) of forage fish were orders of magnitude greater during the winter months (November-February), due to the presence of schools of overwintering Pacific herring ( Clupea pallasi). Within the winter months, herring consistently aggregated at a few areas, and these areas persisted throughout the season and among years. Thus, our study area was characterized by seasonally variable, highly abundant but highly patchily distributed forage fish hot spots. More importantly, the persistence of these forage fish hot spots was an important characteristic in determining whether foraging sea lions utilized them. Over 40% of the variation in the distribution of sea lions on our surveys was explained by the persistence of forage fish hot spots. Using a simple spatial model, we demonstrate that when the density of these hot spots is low, effort necessary to locate these spots is minimized when those spots persist through time. In contrast, under similar prey densities but lower persistence, effort increases dramatically. Thus an important characteristic of pelagic hot spots is their persistence, allowing predators to predict their locations and concentrate search efforts accordingly.

  14. Individual foraging, activity level and longevity in the stingless bee Melipona beecheii in Costa Rica (Hymenoptera, Apidae, Meliponinae)

    NARCIS (Netherlands)

    Biesmeijer, J.C.; Tóth, E.

    1998-01-01

    Foraging behaviour of individually marked workers of Melipona beecheii (Meliponinae) was monitored in Costa Rica to investigate individual specialisation for different materials and how this influences foraging longevity. The majority of the individuals harvested one commodity (pollen, nectar or

  15. Ecology of selected marine communities in Glacier Bay: Zooplankton, forage fish, seabirds and marine mammals

    Science.gov (United States)

    Robards, Martin D.; Drew, Gary S.; Piatt, John F.; Anson, Jennifer Marie; Abookire, Alisa A.; Bodkin, James L.; Hooge, Philip N.; Speckman, Suzann G.

    2003-01-01

    We studied oceanography (including primary production), secondary production, small schooling fish (SSF), and marine bird and mammal predators in Glacier Bay during 1999 and 2000. Results from these field efforts were combined with a review of current literature relating to the Glacier Bay environment. Since the conceptual model developed by Hale and Wright (1979) ‘changes and cycles’ continue to be the underlying theme of the Glacier Bay ecosystem. We found marked seasonality in many of the parameters that we investigated over the two years of research, and here we provide a comprehensive description of the distribution and relative abundance of a wide array of marine biota. Glacier Bay is a tidally mixed estuary that leads into basins, which stratify in summer, with the upper arms behaving as traditional estuaries. The Bay is characterized by renewal and mixing events throughout the year, and markedly higher primary production than in many neighboring southeast Alaska fjords (Hooge and Hooge, 2002). Zooplankton diversity and abundance within the upper 50 meters of the water column in Glacier Bay is similar to communities seen throughout the Gulf of Alaska. Zooplankton in the lower regions of Glacier Bay peak in abundance in late May or early June, as observed at Auke Bay and in the Gulf of Alaska. The key distinction between the lower Bay and other estuaries in the Gulf of Alaska is that a second smaller peak in densities occurs in August. The upper Bay behaved uniformly in temporal trends, peaking in July. Densities had begun to decline in August, but were still more than twice those observed in that region in May. The highest density of zooplankton observed was 17,870 organisms/m3 in Tarr Inlet during July. Trends in zooplankton community abundance and diversity within the lower Bay were distinct from upper-Glacier Bay trends. Whereas the lower Bay is strongly influenced by Gulf of Alaska processes, local processes are the strongest influence in the upper

  16. Effects of habitat composition and landscape structure on worker foraging distances of five bumble bee species.

    Science.gov (United States)

    Redhead, John W; Dreier, Stephanie; Bourke, Andrew F G; Heard, Matthew S; Jordan, William C; Sumner, Seirian; Wang, Jinliang; Carvell, Claire

    2016-04-01

    Bumble bees (Bombus spp.) are important pollinators of both crops and wildflowers. Their contribution to this essential ecosystem service has been threatened over recent decades by changes in land use, which have led to declines in their populations. In order to design effective conservation measures, it is important to understand the effects of variation in landscape composition and structure on the foraging activities of worker bumble bees. This is because the viability of individual colonies is likely to be affected by the trade-off between the energetic costs of foraging over greater distances and the potential gains from access to additional resources. We used field surveys, molecular genetics, and fine resolution remote sensing to estimate the locations of wild bumble bee nests and to infer foraging distances across a 20-km² agricultural landscape in southern England, UK. We investigated five species, including the rare B. ruderatus and ecologically similar but widespread B. hortorum. We compared worker foraging distances between species and examined how variation in landscape composition and structure affected foraging distances at the colony level. Mean worker foraging distances differed significantly between species. Bombus terrestris, B. lapidarius, and B. ruderatus exhibited significantly greater mean foraging distances (551, 536, and 501 m, respectively) than B. hortorum and B. pascuorum (336 and 272 m, respectively). There was wide variation in worker foraging distances between colonies of the same species, which was in turn strongly influenced by the amount and spatial configuration of available foraging habitats. Shorter foraging distances were found for colonies where the local landscape had high coverage and low fragmentation of semi-natural vegetation, including managed agri-environmental field margins. The strength of relationships between different landscape variables and foraging distance varied between species, for example the strongest

  17. Rumen passage kinetics of forage and concentrate derived fiber in dairy cows

    DEFF Research Database (Denmark)

    Krämer, Monika; Lund, Peter; Weisbjerg, Martin Riis

    2013-01-01

    , were used in a completely randomized block experiment. Treatments differed in forage type (corn silage versus grass silage) and forage:concentrate ratio (50:50 versus 75:25 on organic matter basis). Fiber passage kinetics were studied based on rumen evacuations and on marker excretion profiles in feces....... The forage type itself (corn silage and grass silage) rather than ration composition seemed to determine the total tract retention time of forage fiber......Rumen passage kinetics of forage and concentrate fiber were analyzed to determine intrinsic feed effects and extrinsic ration effects on the retention time of fiber in the rumen. Sixteen Danish Holstein cows (557 + 37 kg body weight, 120 + 21 days in milk, mean + SD), 8 fitted with ruminal cannulas...

  18. Influence of forage inclusion in the diet on ileal and total tract digestibility

    DEFF Research Database (Denmark)

    Jørgensen, Henry; Carlson, Dorthe; Lærke, Helle Nygaard

    2012-01-01

    The present investigation aimed to study the ileal and total tract digestibility of 3 forages (clover–grass, clover–grass silage, and fi eld pea (Pisum sativum)–barley (Hordeum vulgare) silage) supplemented to a basal diet. A total of 24 pigs, adapted to eating forages by supplementing a basal feed...... throughout the whole experiment. The intake of forages was low and quite variable and on average accounted for only 10 to 12% of the DMI. Ileal digestibility of protein estimated by collection from the T-cannula was higher (P = 0.031) than the digestibility estimated by the slaughter technique indicating...... in the diet as forage reduced (P pea– barley silage. In organic slaughter pig production, the overall energy supply from these forages is limited, but they may play an important role in satiety...

  19. Temporal pattern of foraging and microhabitat use by Galápagos marine iguanas, Amblyrhynchus cristatus.

    Science.gov (United States)

    Buttemer, William A; Dawson, William R

    1993-10-01

    We observed a colony of marine iguanas (Amblyrhynchus cristatus) on Isla Fernandina, Galápagos, Ecuador, while measuring local micrometeorological and tidal conditions. We found size-related differences in foraging mode, with smaller iguanas feeding intertidally during daytime low tides and larger iguanas feeding subtidally. Despite having greater opportunity, subtidal foragers did not time their foraging bouts or exploit their environment in ways that optimized their period at high body temperature. Instead, the foraging schedule of these iguanas served to maximize their rate of rewarming following emergence from the cool sea. Intertidal feeders, by contrast, showed much greater behavioral flexibility in attempting to exploit their thermal environment. We suggest that size-ordered differences in marine iguana thermoregulatory behavior reflect underlying ontogenetic changes in costs and benefits of thermoregulation due to differences in predator pressure, quantity of food and electrolytes taken at each feeding, mode of foraging, and agonistic tendencies.

  20. Heat, sight and scent: multiple cues influence foraging site selection by an ambush-foraging snake Hoplocephalus bungaroides (Elapidae

    Directory of Open Access Journals (Sweden)

    Weiguo DU, Jonathan K. WEBB, Richard SHINE

    2009-08-01

    Full Text Available Most mobile organisms respond to multiple cues when selecting habitat types, and laboratory experiments that manipulate only single cues may fail to reveal the true complexity of habitat-selection behaviour. In south-eastern Australia, broad-headed snakes Hoplocephalus bungaroides (Elapidae lie in wait under sun-warmed rocks to ambush velvet geckos Oedura leseuerii (Gekkonidae. Previous laboratory work has shown that both the geckos and the snakes actively select hotter rather than colder rocks, and that the snakes actively select rocks scented by geckos. We manipulated rock temperature and the presence of two types of cues from geckos (chemical and visual information to clarify the causal basis for foraging site selection by the juveniles of this snake. When given a choice between cold lizard-scented rocks and hot unscented rocks, our captive snakes gave a higher priority to lizard scent than to temperature. The snakes also selected shelter-sites that provided visual as well as scent cues from lizards, rather than shelter-sites with scent cues alone. Thus, although broad-headed snakes show a direct preference for hotter rather than colder rocks in the laboratory, their choice of foraging site in the field may also be influenced by the presence of scent cues from prey. Our laboratory results suggest that habitat selection by broad-headed snakes may be more complex than has been suggested by previous single-factor laboratory trials[Current Zoology 55(4: 266–271, 2009].

  1. Modelling Pasture-based Automatic Milking System Herds: Grazeable Forage Options

    Directory of Open Access Journals (Sweden)

    M. R. Islam

    2015-05-01

    Full Text Available One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS is to grow forages within a 1-km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM model. Three different basic simulation scenarios (with irrigation were carried out using forage crops (namely maize, soybean and sorghum for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Niño years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.

  2. Corticosterone and foraging behavior in a diving seabird: the Adélie penguin, Pygoscelis adeliae.

    Science.gov (United States)

    Angelier, Frédéric; Bost, Charles-André; Giraudeau, Mathieu; Bouteloup, Guillaume; Dano, Stéphanie; Chastel, Olivier

    2008-03-01

    Because hormones mediate physiological or behavioral responses to intrinsic or extrinsic stimuli, they can help us understand how animals adapt their foraging decisions to energetic demands of reproduction. Thus, the hormone corticosterone deserves specific attention because of its influence on metabolism, food intake and locomotor activities. We examined the relationships between baseline corticosterone levels and foraging behavior or mass gain at sea in a diving seabird, the Adélie penguin, Pygoscelis adeliae. Data were obtained from free-ranging penguins during the brooding period (Adélie Land, Antarctica) by using satellite transmitters and time-depth-recorders. The birds were weighed and blood sampled before and after a foraging trip (pre-trip and post-trip corticosterone levels, respectively). Penguins with elevated pre-trip corticosterone levels spent less time at sea and stayed closer to the colony than penguins with low pre-trip corticosterone levels. These short trips were associated with a higher foraging effort in terms of diving activity and a lower mass gain at sea than long trips. According to previous studies conducted on seabird species, these results suggest that penguins with elevated pre-trip corticosterone levels might maximize the rate of energy delivery to the chicks at the expense of their body reserves. Moreover, in all birds, corticosterone levels were lower post-foraging than pre-foraging. This decrease could result from either the restoration of body reserves during the foraging trip or from a break in activity at the end of the foraging trip. This study demonstrates for the first time in a diving predator the close relationships linking foraging behavior and baseline corticosterone levels. We suggest that slight elevations in pre-trip corticosterone levels could play a major role in breeding effort by facilitating foraging activity in breeding seabirds.

  3. Modelling Pasture-based Automatic Milking System Herds: Grazeable Forage Options.

    Science.gov (United States)

    Islam, M R; Garcia, S C; Clark, C E F; Kerrisk, K L

    2015-05-01

    One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1-km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Niño years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.

  4. Feeding-Related Traits Are Affected by Dosage of the foraging Gene in Drosophila melanogaster.

    Science.gov (United States)

    Allen, Aaron M; Anreiter, Ina; Neville, Megan C; Sokolowski, Marla B

    2017-02-01

    Nutrient acquisition and energy storage are critical parts of achieving metabolic homeostasis. The foraging gene in Drosophila melanogaster has previously been implicated in multiple feeding-related and metabolic traits. Before foraging's functions can be further dissected, we need a precise genetic null mutant to definitively map its amorphic phenotypes. We used homologous recombination to precisely delete foraging, generating the for 0 null allele, and used recombineering to reintegrate a full copy of the gene, generating the {for BAC } rescue allele. We show that a total loss of foraging expression in larvae results in reduced larval path length and food intake behavior, while conversely showing an increase in triglyceride levels. Furthermore, varying foraging gene dosage demonstrates a linear dose-response on these phenotypes in relation to foraging gene expression levels. These experiments have unequivocally proven a causal, dose-dependent relationship between the foraging gene and its pleiotropic influence on these feeding-related traits. Our analysis of foraging's transcription start sites, termination sites, and splicing patterns using rapid amplification of cDNA ends (RACE) and full-length cDNA sequencing, revealed four independent promoters, pr1-4, that produce 21 transcripts with nine distinct open reading frames (ORFs). The use of alternative promoters and alternative splicing at the foraging locus creates diversity and flexibility in the regulation of gene expression, and ultimately function. Future studies will exploit these genetic tools to precisely dissect the isoform- and tissue-specific requirements of foraging's functions and shed light on the genetic control of feeding-related traits involved in energy homeostasis. Copyright © 2017 by the Genetics Society of America.

  5. Dynamics of foraging trails in the Neotropical termite Velocitermes heteropterus (Isoptera: Termitidae).

    Science.gov (United States)

    Haifig, Ives; Jost, Christian; Fourcassié, Vincent; Zana, Yossi; Costa-Leonardo, Ana Maria

    2015-09-01

    Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night. Our aim was to understand the processes involved in the formation of foraging trails, from the exploration of new unmarked areas to the recruitment of individuals to food and the stabilization of traffic on the trails, as well as the participation of the different castes during these processes. Foraging trails were videotaped in the laboratory and the videos were then analyzed both manually and automatically to assess the flow of individuals and the caste ratio on the trails as well as to examine the spatial organization of traffic over time. Foraging trails were composed of minor workers, major workers, and soldiers. The flow of individuals on the trails gradually increased from the beginning of the exploration of new areas up to the discovery of the food. The caste ratio remained constant throughout the foraging excursion: major workers, minor workers and soldiers forage in a ratio of 8:1:1, respectively. The speed of individuals was significantly different among castes, with major workers and soldiers being significantly faster than minor workers. Overall, our results show that foraging excursions in V. heteropterus may be divided in three different phases, characterized by individual speeds, differential flows and lane segregation. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. The foraging behavior of the Large-headed Flatbill, Ramphotrigon megacephalum and the Dusky-tailed Flatbill, Ramphotrigon fuscicauda (Aves: Tyrannidae

    Directory of Open Access Journals (Sweden)

    Tomaz Nascimento de Melo

    Full Text Available ABSTRACT Southwestern Amazonia has great bird diversity which includes birds specialized in bamboo forests. In this region, bamboo is considered a key element of the landscape. The objective of this study was to investigate and describe the foraging behavior of the Large-headed Flatbill, Ramphotrigon megacephalum (Swainson, 1835 and the Dusky-tailed Flatbill, Ramphotrigon fuscicauda Chapman, 1925, which occur sympatrically in the region and are considered bamboo specialists. This study was conducted between November 2013 and September 2014, within two fragments in the eastern portion of the state of Acre: Fazenda Experimental Catuaba, in the municipality of Senador Guiomard; and Reserva Florestal Humaitá, in Porto Acre. A total of 109 and 97 foraging events were registered, for the Large-headed Flatbill and the Dusky-tailed Flatbill, respectively. The two species frequently used bamboos for searching and capturing their prey. However, the large-headed Flatbill was more specialized in bamboo substrates. Both species use similar foraging techniques and the differences found between the two are minor, but when taken together, these differences may explain their ability to co-exist.

  7. Investigation of Yield and Yield Components of Canary Seed Forage (Phalaris canariensis L. in Response to Different Levels of Irrigation, Organic and Chemical Fertilizers and their integration

    Directory of Open Access Journals (Sweden)

    V Varnaseri Ghandali

    2016-12-01

    Full Text Available Introduction Canary seed (Phalaris canariensis L. is a forage plant from Poaceae family. This plant is drought tolerant. Canary seed is originally a native to Mediterranean region, which can be grown commercially in several parts of the word, especially in semi-arid conditions. Increasing growth of population and lack of ability of pastures to satisfy the food requirement of animal has led to more interest in cultivating forage plants. In this regard, Canary seed having properties such as high yield per unit area, high tillering power, very fast growth and appropriate nutritional value, is of considerable importance and its cultivation development especially in arid and semi-arid regions can be effective in providing part of the country forage needs. Optimum water requirement is considered as one the important factors to obtain a high growth and yield of the product. On the other hand, Iran is located in arid and semi-arid climate region of the world . Therefore, determination of appropriate amount of irrigation water can lead to the improvement of water use efficiency and preventing the water loss. In order to achieve a high yield and desirable quality in plants one of the important requirements in agricultural planning is the evaluation of different systems of plant feeding. By applying an appropriate method in soil productivity, in addition to protecting the environment, optimization of water usage, reduction of erosion and protection of biodiversity can be increased. Therefore, gradually replacing chemical fertilizers with biological and organic fertilizers will result in providing feed requirements of plants, improvement of physical, chemical and biological conditions of soil and reduction of adverse environmental effects resulting from application of chemical inputs. The aim of this research was to study the effects of deficit irrigation and fertilizer management based on sole chemical and organic fertilizers or their integrated

  8. Commensal foraging with Bewick’s Swans Cygnus bewickii doubles instantaneous intake rate of Common Pochards Aythya ferina

    NARCIS (Netherlands)

    Gyimesi, A.; van Lith, B.; Nolet, B.A.

    2012-01-01

    Aquatically foraging Bewick’s Swans Cygnus bewickii have been repeatedly reported to be accompanied by diving ducks, but the exact nature of this relationship is unclear. Based on field observations, we found a strong correlation between the number of foraging swans and the number of foraging Common

  9. Meeting reproductive demands in a dynamic upwelling system: foraging strategies of a pursuit-diving seabird, the marbled murrelet

    Science.gov (United States)

    M. Zachariah Peery; Scott H. Newman; Curt D. Storlazzi; Steven R. Beissinger

    2009-01-01

    Seabirds maintain plasticity in their foraging behavior to cope with energy demands and foraging constraints that vary over the reproductive cycle, but behavioral studies comparing breeding and nonbreeding individuals are rare. Here we characterize how Marbled Murrelets (Brachyramphus marmoratus) adjust their foraging effort in response to changes...

  10. Foraging plasticity by a keystone excavator, the white-headed woodpecker, in managed forests: Are there consequences for productivity?

    Science.gov (United States)

    Teresa J. Lorenz; Kerri T. Vierling; Jeffrey M. Kozma; Janet E. Millard

    2016-01-01

    Information on the foraging ecology of animals is important for conservation and management, particularly for keystone species whose presence affects ecosystem health. We examined foraging by an at-risk cavity excavator, the white-headed woodpecker (Picoides albolarvatus). The foraging needs of this species are used to inform management of...

  11. Antennal proteome comparison of sexually mature drone and forager honeybees.

    Science.gov (United States)

    Feng, Mao; Song, Feifei; Aleku, Dereje Woltedji; Han, Bin; Fang, Yu; Li, Jianke

    2011-07-01

    Honeybees have evolved an intricate system of chemical communication to regulate their complex social interactions. Specific proteins involved in odorant detection most likely supported this chemical communication. Odorant reception takes place mainly in the antennae within hairlike structures called olfactory sensilla. Antennal proteomes of sexually mature drone and forager worker bees (an age group of bees assigned to perform field tasks) were compared using two-dimensional electrophoresis, mass spectrometry, quantitative real-time polymerase chain reaction, and bioinformatics. Sixty-one differentially expressed proteins were identified in which 67% were highly upregulated in the drones' antennae whereas only 33% upregulated in the worker bees' antennae. The antennae of the worker bees strongly expressed carbohydrate and energy metabolism and molecular transporters signifying a strong demand for metabolic energy and odorant binding proteins for their foraging activities and other olfactory responses, while proteins related to fatty acid metabolism, antioxidation, and protein folding were strongly upregulated in the drones' antennae as an indication of the importance for the detection and degradation of sex pheromones during queen identification for mating. On the basis of both groups of altered antenna proteins, carbohydrate metabolism and energy production and molecular transporters comprised more than 80% of the functional enrichment analysis and 45% of the constructed biological interaction networks (BIN), respectively. This suggests these two protein families play crucial roles in the antennal olfactory function of sexually mature drone and forager worker bees. Several key node proteins in the BIN were validated at the transcript level. This first global proteomic comparative analysis of antennae reveals sex-biased protein expression in both bees, indicating that odorant response mechanisms are sex-specific because of natural selection for different olfactory

  12. Recent developments in forage evaluation with special reference to practical applications

    Directory of Open Access Journals (Sweden)

    P. HUHTANEN

    2008-12-01

    Full Text Available The present re-evaluation of a dataset of systematically collected laboratory analyses and in vivo digestibility information for several types of silages gives convincing evidence of the biological weaknesses of feed characterisation based on the proximate feed analysis. The problems include intrinsic failures of the analysis in describing cause-response relationships between forage composition and digestibility, and heavy dependency of the equations on forage specific and environmental factors. It is concluded that proximate analysis is not suitable for characterisation of neither forages nor concentrate feedstuffs. In vitro pepsin-cellulase solubility of organic matter (OMS and concentration of indigestible neutral detergent fibre (iNDF predicted forage organic matter digestibility (OMD with an acceptable accuracy for practical feed evaluation purposes provided that forage type dependent correction equations were employed. The revised detergent system dividing forage dry matter (DM into almost completely available neutral detergent solubles (NDS, and insoluble residue (neutral detergent fibre, NDF shows potential for future development. The combined use of long-term in situ ruminal incubation and NDF fractionation can be used to divide forage DM into three biologically meaningful fractions: NDS, iNDF and potentially digestible NDF (pdNDF. The summative models can then be used to predict forage D-value, i.e. apparently digestible organic matter in forage (g kg-1 DM. The models sum digestible NDS, which can be determined by Lucas equation, and digestible NDF (dNDF, which is the amount of pdNDF that is actually digested during any specific fermentation or retention time. Forage type specific summative models were as good as regression equations based on OMS or iNDF in predicting forage D-value and general summative models gave better results than general equations based on iNDF and especially OMS. If the goal is to reduce prediction error of D

  13. Constitutive and Operational Variation of Learning in Foraging Predatory Mites.

    Science.gov (United States)

    Seiter, Michael; Schausberger, Peter

    2016-01-01

    Learning is widely documented across animal taxa but studies stringently scrutinizing the causes of constitutive or operational variation of learning among populations and individuals are scarce. The ability to learn is genetically determined and subject to constitutive variation while the performance in learning depends on the immediate circumstances and is subject to operational variation. We assessed variation in learning ability and performance of plant-inhabiting predatory mites, Amblyseius swirskii, caused by population origin, rearing diet, and type of experience. Using an early learning foraging paradigm, we determined that homogeneous single prey environments did not select for reduced learning ability, as compared to natural prey-diverse environments, whereas a multi-generational pollen diet resulted in loss of learning, as compared to a diet of live prey. Associative learning produced stronger effects than non-associative learning but both types of experience produced persistent memory. Our study represents a key example of environmentally caused variation in learning ability and performance.

  14. Using gamma irradiation to improve sterile turf and forage bermudagrasses

    International Nuclear Information System (INIS)

    Burton, G.W.; Georgia Univ., Tifton

    1976-01-01

    The widely-used Tif-series of turf bermudagrasses - Tifgreen, Tifway, and Tifdwarf - are vegetatively propagated sterile triploids that cannot be improved by conventional breeding methods. Dormant stolons, washed free of soil and cut into one-or two-node sections were treated with varying dosages of EMS (ethyl methane sulfonate) and gamma irradiation ranging from 7 to 12 kR. EMS failed to produce noticeable variants but gamma irradiation from a Cobalt 60 source created 158 mutants. These mutants differed in many characters such as leaf size, hairiness, stem diameter, internode length, basic plant color, herbicide tolerance, spreading rate, and nematode resistance. Attempts to improve the winterhardiness of tetraploid sterile Coastcross-1 forage bermudagrass by exposing over 1,400,000 sprigs (vegetative stems) to 7 kR of gamma rays gave chlorophyll deficient mutants but progress in increasing winterhardiness has not been established. (author)

  15. Forage Quality Determined by Botanic Species’ Contribution on Permanent Pastures

    Directory of Open Access Journals (Sweden)

    Neculai Dragomir

    2011-10-01

    Full Text Available The chemical composition of the forage obtained from permanent pastures is determined, in its turn, by the floristic structure consisted of species belonging to various botanic families. Each botanic species presents a specific chemical content and a certain contribution to the balancing of forage’s nutritional value. The chemical analyses performed, at species level, revealed the importance of the “diverse” species, which, with their content in mineral elements, may influence animals’ capacity of production and reproduction. Some of the species, considered to be weeds within the permanent pastures’ floristic composition, presented high crude protein content values: Achillea millefolium with 24.22%, Taraxacum officinale 24.06%, Urtica dioica with 32.46%, Plantago major with 17.04%, etc.

  16. Benefits of collective intelligence: Swarm intelligent foraging, an ethnographic research

    Directory of Open Access Journals (Sweden)

    Sivave Mashingaidze

    2014-12-01

    Full Text Available Wisdom of crowds; bees, colonies of ants, schools of fish, flocks of birds, and fireflies flashing synchronously are all examples of highly coordinated behaviors that emerge from collective, decentralized intelligence. This article is an ethnographic study of swarm intelligence foraging of swarms and the benefits derived from collective decision making. The author used using secondary data analysis to look at the benefits of swarm intelligence in decision making to achieve intended goals. Concepts like combined decision making and consensus were discussed and four principles of swarm intelligence were also discussed viz; coordination, cooperation, deliberation and collaboration. The research found out that collective decision making in swarms is the touchstone of achieving their goals. The research further recommended corporate to adopt collective intelligence for business sustainability.

  17. Consumption and foraging behaviors for common stimulants (nicotine, caffeine).

    Science.gov (United States)

    Phillips, James G; Currie, Jonathan; Ogeil, Rowan P

    2016-01-01

    Models are needed to understand the emerging capability to track consumers' movements. Therefore, we examined the use of legal and readily available stimulants that vary in their addictive potential (nicotine, caffeine). One hundred sixty-six participants answered the Kessler Psychological Distress Scale (K10), the Severity of Dependence Scale for nicotine and caffeine, and reported the number of times and locations stimulants were purchased and used. On average, nicotine dependent individuals made their purchases from 2 locations, while caffeine dependent individuals consumed caffeine at 2 locations, but some people exhibited a greater range and intensity of use. Stimulant foraging behavior could be described by power laws, and is exacerbated by dependency. The finding has implications for attempts to control substance use.

  18. Quorum decision-making in foraging fish shoals.

    Directory of Open Access Journals (Sweden)

    Ashley J W Ward

    Full Text Available Quorum responses provide a means for group-living animals to integrate and filter disparate social information to produce accurate and coherent group decisions. A quorum response may be defined as a steep increase in the probability of group members performing a given behaviour once a threshold minimum number of their group mates already performing that behaviour is exceeded. In a previous study we reported the use of a quorum response in group decision-making of threespine sticklebacks (Gasterosteus aculeatus under a simulated predation threat. Here we examine the use of quorum responses by shoals of sticklebacks in first locating and then leaving a foraging patch. We show that a quorum rule explains movement decisions by threespine sticklebacks toward and then away from a food patch. Following both to and from a food patch occurred when a threshold number of initiators was exceeded, with the threshold being determined by the group size.

  19. Radiation and temperature influence on forage grasses yield

    International Nuclear Information System (INIS)

    Vadell, J.; Medrano, H.

    1986-01-01

    Biomass production has been studied in forage plants, as well as the temperature and radiation effects on plant growth. Four cultivars of grasses: Lolium multiflorum var westerwoldicum cv Promenade, Lolium perenne cvs Combi and Compas and Bromus inermis were growing as microswards in a growth chamber with constant temperature and outdoors. A field assay was done also with the same cultivars. L. multiflorum was the highest productive genotype anywhere showing also more active growth at low temperatures. Total production showed significant differences among genotypes. It was also a clear correspondence among microswards and field productions. Highest efficiency values (in % of PAR accumulated as dry matter) was obtained in 6th cut (April) achieving to 5.18 % in L. multiflorum. Biomass production variations through the growth period show a low correlation with <> and very high correlation with total irradiation received by the sward between consecutive cuts [es

  20. Influence of poisoned prey on foraging behavior of ferruginous hawks

    Science.gov (United States)

    Vyas, Nimish B.; Kuncir, Frank; Clinton, Criss C.

    2017-01-01

    We recorded 19 visits by ferruginous hawks (Buteo regalis) over 6 d at two black–tailed prairie dog (Cynomys ludovicianus) subcolonies poisoned with the rodenticide Rozol® Prairie Dog Bait (0.005% chlorophacinone active ingredient) and at an adjacent untreated subcolony. Before Rozol® application ferruginous hawks foraged in the untreated and treated subcolonies but after Rozol® application predation by ferruginous hawks was only observed in the treated subcolonies. We suggest that ferruginous hawks' preference for hunting in the treated subcolonies after Rozol® application was influenced by the availability of easy-to-capture prey, presumably due to Rozol® poisoning. The energetically beneficial behavior of favoring substandard prey may increase raptor encounters with rodenticide exposed animals if prey vulnerability has resulted from poisoning.

  1. Stochastic recruitment leads to symmetry breaking in foraging populations

    Science.gov (United States)

    Biancalani, Tommaso; Dyson, Louise; McKane, Alan

    2014-03-01

    When an ant colony is faced with two identical equidistant food sources, the foraging ants are found to concentrate more on one source than the other. Analogous symmetry-breaking behaviours have been reported in various population systems, (such as queueing or stock market trading) suggesting the existence of a simple universal mechanism. Past studies have neglected the effect of demographic noise and required rather complicated models to qualitatively reproduce this behaviour. I will show how including the effects of demographic noise leads to a radically different conclusion. The symmetry-breaking arises solely due to the process of recruitment and ceases to occur for large population sizes. The latter fact provides a testable prediction for a real system.

  2. Agonistic asymmetries and the foraging ecology of Bald Eagles

    Science.gov (United States)

    Knight, Richard L.; Skagen, Susan Knight

    1988-01-01

    We investigated the effects of both asymmetries and differing food levels on contest outcomes of wintering Bald Eagles (Haliaeetus leucocephalus) feeding on chum salmon (Oncorhynchus keta) carcasses. Large eagles, regardless of age, were more successful in pirating than smaller eagles. Small pirating eagles were usually unsuccessful unless they were adults attempting to supplant other small eagles. Feeding eagles were more successful in defeating pirating eagles according to (1) whether their heads were up to prior to a pirating attempt, (2) how long their heads had been up, and (3) whether they displayed. During periods of food scarcity pirating eagles were less successful, a fact attributed in a proximate sense to the increase incidence of retaliation by feeding birds. When food was scarce and eagles had a choice between scavenging the pirating, they chose to scavenge more often. Body size appears to be an important factor in determining social dominance and influencing differences in foraging modes of wintering Bald Eagles.

  3. Breeding short-tailed shearwaters buffer local environmental variability in south-eastern Australia by foraging in Antarctic waters.

    Science.gov (United States)

    Berlincourt, Maud; Arnould, John P Y

    2015-01-01

    Establishing patterns of movements of free-ranging animals in marine ecosystems is crucial for a better understanding of their feeding ecology, life history traits and conservation. As central place foragers, the habitat use of nesting seabirds is heavily influenced by the resources available within their foraging range. We tested the prediction that during years with lower resource availability, short-tailed shearwaters (Puffinus tenuirostris) provisioning chicks should increase their foraging effort, by extending their foraging range and/or duration, both when foraging in neritic (short trips) and distant oceanic waters (long trips). Using both GPS and geolocation data-loggers, at-sea movements and habitat use were investigated over three breeding seasons (2012-14) at two colonies in southeastern Australia. Most individuals performed daily short foraging trips over the study period and inter-annual variations observed in foraging parameters where mainly due to few individuals from Griffith Island, performing 2-day trips in 2014. When performing long foraging trips, this study showed that individuals from both colonies exploited similar zones in the Southern Ocean. The results of this study suggest that individuals could increase their foraging range while exploiting distant feeding zones, which could indicate that short-tailed shearwaters forage in Antarctic waters not only to maintain their body condition but may also do so to buffer against local environmental stochasticity. Lower breeding performances were associated with longer foraging trips to distant oceanic waters in 2013 and 2014 indicating they could mediate reductions in food availability around the breeding colonies by extending their foraging range in the Southern Ocean. This study highlights the importance of foraging flexibility as a fundamental aspect of life history in coastal/pelagic marine central place foragers living in highly variable environments and how these foraging strategies are use to

  4. Foraging in maize field areas: A risky business?

    Science.gov (United States)

    Boily, Monique; Aras, Philippe; Jumarie, Catherine

    2017-12-01

    In Quebec, Canada, the cultivation of maize dominates the agricultural territory. This crop requires a sustained supply of fertilizers from different sources: chemical, natural or from residual materials (sludge). These amendments contain metallic trace elements, which may lead to metal-contaminated maize pollen, a possible source of prooxidants for the foraging bees. Our objective was to determine whether maize fields environment influences the oxidation processes and the accumulation of metals in bees. A few days prior to pollen shedding, beehives were installed in maize fields: one organically grown (site A) and three conventionally grown (sites B, C and D). Soil, maize pollen and bees were analyzed for metal content. Every 15days, bees were collected and analyzed for peroxidation of lipids, metallothionein-like proteins (MTLPs), proteins, retinoids and lipophilic antioxidants (carotenoids and α-tocopherol). The compound β-carotene was the most abundant in bees from all sites, followed by α-carotene, β-cryptoxanthin, α-cryptoxanthin, zeaxanthin and lutein. Retinaldehyde and retinol varied according to times and sites without demonstrating clear trends. However, significant differences between sites were noted in 13-cis-retinoic acid and two retinoic acid metabolites measured in bees, suggesting alteration in the reduction-oxidation processes. In line with these results, the level of lipid peroxidation was globally higher in sites B, C and D compared with the organic site. Higher concentrations of metals were observed in soil and pollen from the field A, but bees metal contents were equal or less than those measured in bees from other sites. Higher bee MTLP levels were measured in sites B, C and D. For most sampling times, the discriminant analysis revealed that the conditions were distinguished by the oxidation processes in bees. Our data suggest that bees foraging in conventionally grown maize fields are at risk of increased oxidative damages which can

  5. Hidden Markov models: the best models for forager movements?

    Science.gov (United States)

    Joo, Rocio; Bertrand, Sophie; Tam, Jorge; Fablet, Ronan

    2013-01-01

    One major challenge in the emerging field of movement ecology is the inference of behavioural modes from movement patterns. This has been mainly addressed through Hidden Markov models (HMMs). We propose here to evaluate two sets of alternative and state-of-the-art modelling approaches. First, we consider hidden semi-Markov models (HSMMs). They may better represent the behavioural dynamics of foragers since they explicitly model the duration of the behavioural modes. Second, we consider discriminative models which state the inference of behavioural modes as a classification issue, and may take better advantage of multivariate and non linear combinations of movement pattern descriptors. For this work, we use a dataset of >200 trips from human foragers, Peruvian fishermen targeting anchovy. Their movements were recorded through a Vessel Monitoring System (∼1 record per hour), while their behavioural modes (fishing, searching and cruising) were reported by on-board observers. We compare the efficiency of hidden Markov, hidden semi-Markov, and three discriminative models (random forests, artificial neural networks and support vector machines) for inferring the fishermen behavioural modes, using a cross-validation procedure. HSMMs show the highest accuracy (80%), significantly outperforming HMMs and discriminative models. Simulations show that data with higher temporal resolution, HSMMs reach nearly 100% of accuracy. Our results demonstrate to what extent the sequential nature of movement is critical for accurately inferring behavioural modes from a trajectory and we strongly recommend the use of HSMMs for such purpose. In addition, this work opens perspectives on the use of hybrid HSMM-discriminative models, where a discriminative setting for the observation process of HSMMs could greatly improve inference performance.

  6. Adaptive intertemporal preferences in foraging-style environments

    Directory of Open Access Journals (Sweden)

    Michael T. Bixter

    2013-06-01

    Full Text Available Decision makers often face choices between smaller more immediate rewards and larger more delayed rewards. For example, when foraging for food, animals must choose between actions that have varying costs (e.g., effort, duration, energy expenditure and varying benefits (e.g., amount of food intake. The combination of these costs and benefits determine what optimal behavior is. In the present study, we employ a foraging-style task to study how humans make reward-based choices in response to the real-time constraints of a dynamic environment. On each trial participants were presented with two rewards that differed in magnitude and in the delay until their receipt. Because the experiment was of a fixed duration, maximizing earnings required decision makers to determine how to trade off the magnitude and the delay associated with the two rewards on each trial. To evaluate the extent to which participants could adapt to the decision environment, specific task characteristics were manipulated, including reward magnitudes (Experiment 1 and the delay between trials (Experiment 2. Each of these manipulations was designed to alter the pattern of choices made by an optimal decision maker. Several findings are of note. First, different choice strategies were observed with the manipulated environmental constraints. Second, despite contextually-appropriate shifts in behavior between conditions in each experiment, choice patterns deviated from theoretical optimality. In particular, the delays associated with the rewards did not exert a consistent influence on choices as required by exponential discounting. Third, decision makers nevertheless performed surprisingly well in all task environments with any deviations from strict optimality not having particularly deleterious effects on earnings. Taken together, these results suggest that human decision makers are capable of exhibiting intertemporal preferences that reflect a variety of environmental constraints.

  7. Hidden Markov models: the best models for forager movements?

    Directory of Open Access Journals (Sweden)

    Rocio Joo

    Full Text Available One major challenge in the emerging field of movement ecology is the inference of behavioural modes from movement patterns. This has been mainly addressed through Hidden Markov models (HMMs. We propose here to evaluate two sets of alternative and state-of-the-art modelling approaches. First, we consider hidden semi-Markov models (HSMMs. They may better represent the behavioural dynamics of foragers since they explicitly model the duration of the behavioural modes. Second, we consider discriminative models which state the inference of behavioural modes as a classification issue, and may take better advantage of multivariate and non linear combinations of movement pattern descriptors. For this work, we use a dataset of >200 trips from human foragers, Peruvian fishermen targeting anchovy. Their movements were recorded through a Vessel Monitoring System (∼1 record per hour, while their behavioural modes (fishing, searching and cruising were reported by on-board observers. We compare the efficiency of hidden Markov, hidden semi-Markov, and three discriminative models (random forests, artificial neural networks and support vector machines for inferring the fishermen behavioural modes, using a cross-validation procedure. HSMMs show the highest accuracy (80%, significantly outperforming HMMs and discriminative models. Simulations show that data with higher temporal resolution, HSMMs reach nearly 100% of accuracy. Our results demonstrate to what extent the sequential nature of movement is critical for accurately inferring behavioural modes from a trajectory and we strongly recommend the use of HSMMs for such purpose. In addition, this work opens perspectives on the use of hybrid HSMM-discriminative models, where a discriminative setting for the observation process of HSMMs could greatly improve inference performance.

  8. Evaluation of wild animals browsing preferences in forage resources

    Directory of Open Access Journals (Sweden)

    Giovanni Argenti

    2017-09-01

    Full Text Available Excessive presence of wild ungulates can produce negative effects on herbaceous crops or woody species, and to face this problem, habitat improvements are often performed to recreate suitable environments for a given animal species and to attract animals far from cultivated crops. A common example of these interventions is represented by grassland restoration and to evaluate the real animal preferences on restored forage resources a proper trial was established in a hilly area of Tuscany (central Italy, inside the historical Park of Pratolino, near Florence. The trial compared six different forage species or mixtures sown in plots: vegetal material was represented by two pure stands (Onobrychis viciifolia and Medicago sativa and four mixtures differing in number and kind of used species. Plots were utilised only by wild animals occurring in the area. Data collection consisted of botanical samples in each plot in different periods to obtain the percent presence of each species. At the same time, a visual estimation of animal intake on all occurring species was performed to obtain the browsing ratio of single species and overall defoliation rate for each species/mixture. Moreover, six camera traps were placed on the boundary of the experimental site to record videos of wild animals browsing in the area for identification of animals actually occurring on different plots and for comparison of these results with botanical data. Vegetation surveys permitted a proper evaluation of animals intake and of their feeding preferences. In general, sown species performed a major role in animal browsing, even if in some periods also a few native species (such as Plantago lanceolata or Cichorium intybus were utilised in a strong way, depending on vegetation context and existing biomass. Camera traps results permitted the identification of browsing animal species (mainly represented by roe deer and plots frequentation resulted to be highly related to animal

  9. Multiple model testing using Chernobyl fallout data of I-131 in forage and milk and Cs-137 in forage, milk, beef and grain. Pt. 1

    International Nuclear Information System (INIS)

    Koehler, H.; Peterson, S.R.; Owen Hoffman, F.

    1991-03-01

    Comprehensive measurements of I-131 and Cs-137 in the environment after the Chernobyl accident provided a unique opportunity for the collection of environmental transfer data sets. These come from 13 locations in the northern hemisphere which experienced levels of contamination that spanned approximately three orders of magnitude. Data have been compiled for radionuclide concentrations in air, rain, pasture vegetation, milk, beef and grain. In addition background information has been collated for factors such as prevailing meteorological conditions, location description, and local agricultural practices. Participants were asked to predict radionuclide concentrations in forage, milk, beef and grain from radionuclide concentrations in air, the daily amounts of precipitation and other pertinent information. This was a blind test in that the locations to which the input data referred were not revealed to the participants until after they had submitted their predictions. Twenty-three models were involved in the study. This report compares observations and predictions for deposition, time- integrated concentrations in forage, milk, beef and grain, to help assess understanding of individual processes, time-dependent concentrations in forage, milk and beef. In general, predictions of time-integrated concentration of I-131 and Cs-137 in forage, milk (normalized for forage) and beef are within a factor of 10 of the observations. About 50% of the predictions of I-131 and Cs-137 in forage and just over 30% of the predictions of those nuclides in milk (normalized for forage) fall within a factor of 2 of the observations. Documentation of the measurements, models, methods of analysis and model results is presented in the appendices. (au) (75 refs.)

  10. Contrasting Foraging Patterns: Testing Resource-Concentration and Dilution Effects with Pollinators and Seed Predators

    Directory of Open Access Journals (Sweden)

    Alexandria Wenninger

    2016-06-01

    Full Text Available Resource concentration effects occur when high resource density patches attract and support more foragers than low density patches. In contrast, resource dilution effects can occur if high density patches support fewer consumers. In this study, we examined the foraging rates of pollinators and seed predators on two perennial plant species (Rudbeckia triloba and Verbena stricta as functions of resource density. Specifically, we examined whether resource-dense patches (densities of flower and seeds on individual plants resulted in greater visitation and seed removal rates, respectively. We also examined whether foraging rates were context-dependent by conducting the study in two sites that varied in resource densities. For pollinators, we found negative relationships between the density of flowers per plant and visitation rates, suggesting dilution effects. For seed predators, we found positive relationships consistent with concentration effects. Saturation effects and differences in foraging behaviors might explain the opposite relationships; most of the seed predators were ants (recruitment-based foragers, and pollinators were mostly solitary foragers. We also found that foraging rates were site-dependent, possibly due to site-level differences in resource abundance and consumer densities. These results suggest that these two plant species may benefit from producing as many flowers as possible, given high levels of pollination and low seed predation.

  11. Evidence of Levy walk foraging patterns in human hunter-gatherers.

    Science.gov (United States)

    Raichlen, David A; Wood, Brian M; Gordon, Adam D; Mabulla, Audax Z P; Marlowe, Frank W; Pontzer, Herman

    2014-01-14

    When searching for food, many organisms adopt a superdiffusive, scale-free movement pattern called a Lévy walk, which is considered optimal when foraging for heterogeneously located resources with little prior knowledge of distribution patterns [Viswanathan GM, da Luz MGE, Raposo EP, Stanley HE (2011) The Physics of Foraging: An Introduction to Random Searches and Biological Encounters]. Although memory of food locations and higher cognition may limit the benefits of random walk strategies, no studies to date have fully explored search patterns in human foraging. Here, we show that human hunter-gatherers, the Hadza of northern Tanzania, perform Lévy walks in nearly one-half of all foraging bouts. Lévy walks occur when searching for a wide variety of foods from animal prey to underground tubers, suggesting that, even in the most cognitively complex forager on Earth, such patterns are essential to understanding elementary foraging mechanisms. This movement pattern may be fundamental to how humans experience and interact with the world across a wide range of ecological contexts, and it may be adaptive to food distribution patterns on the landscape, which previous studies suggested for organisms with more limited cognition. Additionally, Lévy walks may have become common early in our genus when hunting and gathering arose as a major foraging strategy, playing an important role in the evolution of human mobility.

  12. Food and foraging preferences of three pteropodid bats in southern India

    Directory of Open Access Journals (Sweden)

    M.R Sudhakaran

    2012-01-01

    Full Text Available A study on the food, foraging and flight height in three species of pteropodid bats, namely Cynopterus sphinx, Rousettus leschenaultii and Pteropus giganteus was conducted in Tirunelveli and Tuticorin districts of southern Tamil Nadu, India. A total of 37 species of plants were identified as potential food plants of the pteropodid bats. The preference for fruits by pteropodids varied according to the developmental stages of fruits namely, immature, unripe and ripe. There is a relationship between the foraging activities of bats and the moon phase. Bats exhibit a varied foraging pattern and flight height. A variation in the foraging flight height was observed in C. sphinx and R. leschenaultii. R. leschenaultii was observed to have a higher foraging echelon than that of the C. sphinx. In our study we found that the C. sphinx forages normally at canopy level (up to 3.5m, R. leschenaultii forages at upper canopy levels (up to 9m and P. giganteus at a height above the canopy area (>9m.

  13. Multidimensional differentiation in foraging resource use during breeding of two sympatric top predators

    Science.gov (United States)

    Friedemann, Guilad; Leshem, Yossi; Kerem, Lior; Shacham, Boaz; Bar-Massada, Avi; McClain, Krystaal M.; Bohrer, Gil; Izhaki, Ido

    2016-10-01

    Ecologically-similar species were found to develop specific strategies to partition their resources, leading to niche differentiation and divergence, in order to avoid interspecific competition. Our study determines multi-dimensional differentiation of two sympatric top-predators, long-legged buzzards (LLB) and short-toed eagles (STE), which recently became sympatric during their breeding season in the Judean Foothills, Israel. By combining information from comprehensive diet and movement analyses we found four dimensions of differentiation: (1) Geographic foraging area: LLB tended to forage relatively close to their nests (2.35 ± 0.62 km), while STE forage far from their nest (13.03 ± 2.20 km) (2) Foraging-habitat type: LLBs forage at low natural vegetation, avoiding cultivated fields, whereas STEs forage in cultivated fields, avoiding low natural vegetation; (3) Diurnal dynamics of foraging: LLBs are uniformly active during daytime, whereas STEs activity peaks in the early afternoon; and (4) Food-niche: while both species largely rely on reptiles (47.8% and 76.3% for LLB and STE, respectively), LLB had a more diverse diet and consumed significantly higher percentages of lizards, while STE consumed significantly higher percentages of snakes. Our results suggest that this multidimensional differentiation allows the spatial coexistence of these two dense populations in the study area.

  14. Foraging intention affects whether willow tits call to attract members of mixed-species flocks.

    Science.gov (United States)

    Suzuki, Toshitaka N; Kutsukake, Nobuyuki

    2017-06-01

    Understanding how individual behaviour influences the spatial and temporal distribution of other species is necessary to resolve the complex structure of species assemblages. Mixed-species bird flocks provide an ideal opportunity to investigate this issue, because members of the flocks are involved in a variety of behavioural interactions between species. Willow tits ( Poecile montanus ) often produce loud calls when visiting a new foraging patch to recruit other members of mixed-species flocks. The costs and benefits of flocking would differ with individual foraging behaviours (i.e. immediate consumption or caching); thus, willow tits may adjust the production of loud calls according to their foraging intention. In this study, we investigated the link between foraging decisions and calling behaviour in willow tits and tested its influence on the temporal cohesion with members of mixed-species flocks. Observations at experimental foraging patches showed that willow tits produced more calls when they consumed food items compared with when they cached them. Playback experiments revealed that these calls attracted flock members and helped to maintain their presence at foraging patches. Thus, willow tits adjusted calling behaviour according to their foraging intention, thereby coordinating the associations with members of mixed-species flocks. Our findings demonstrate the influence of individual decision-making on temporal cohesion with other species and highlight the importance of interspecific communication in mixed-species flocking dynamics.

  15. EXPLORATION UNDER SHADE PLANTS OF CASSAVA AND IT’S POTENTIAL AS FORAGE

    Directory of Open Access Journals (Sweden)

    Novia Qomariyah

    2014-01-01

    Full Text Available Utilization of forage plants growing among cassava (Manihot esculenta Crantz is not optimal. Potential for development of integration of both very large and mutually beneficial. Purpose of this study is to explore and identify types of forage that grows in shade of the cassava plant and potential for development as a source of forage. This study took place in March 2014 Month held at IPB Sinar Sari Complex Dramaga. This research method to define area of cassava plants as treatments that cassava plants were planted separately with another crop (monoculture and cassava crops are planted among crops and horticultural crops such as pariah plants, beans, squash and corn (polyculture. Furthermore, observed and forage samples taken were grown in both location and made herbarium and identified its kind. Results: forage crops are grown between cassava monoculture is more diverse than polyculture. Types of forage crops grown on cassava monoculture is Echinochloa colona, Setaria barbata, Family Juncaceae, Cyperus sp., Conjugatum paspalum, Cynodon dactylon, Stenotaphrum secundatum, Axonophus compressus (Swartz P. Beauv, Eleusine indica and Panicum maximum. Types of forage crops grown on cassava polyculture is colona Echinochloa, Setaria barbata, Family Juncaceae, Cyperus sp., Stenotaphrum secundatum, Eleusine indica and Leucaena leucephala.

  16. A systems approach for the evaluation of ethanol production based on forages

    Energy Technology Data Exchange (ETDEWEB)

    Alvo, P. [McGill Univ., Ste. Anne de Bellevue, PQ (Canada). Macdonald Coll.; Savoie, P. [Agriculture and Agri-Food Canada, Quebec, PQ (Canada). Saine-Foy Research Centre; Tremblay, D. [Laval Univ., Quebec, PQ (Canada). Dept. de Genie Rural; Emond, J.-P.; Turcotte, G. [Laval Univ., Quebec City, PQ (Canada). Dept. de Sciences et Technologie des Aliments

    1996-04-01

    A systems approach is proposed to simultaneously consider the agronomic aspects of forage production and the processing aspects related to the extraction of a glucose or xylose substrate, its fermentation into ethanol and the optimal utilization of co-products (protein meal, fibrous residue). The energy to produce and transport forage on the farm was estimated to be only 375 MJ/t dry matter (DM) when liquid manure was used and 1165 MJ/t DM when mineral fertilizer was used. An additional 126 MJ/t DM would be required to transport it to a processing plant. In contrast, whole-plant corn production using mineral fertilizer required about 3211 MJ/t DM, but it had a potential ethanol yield 3.2 times greater per unit area than perennial forage. A forage system with mechanical juice extraction resulted in 8-20% of the original forage dry matter available in a liquid substrate with subsequent protein meal separation and the fermentation of soluble sugars into ethanol. Another forage system with relatively complete conversion of cellulose and hemicellulose into simple sugars by thermal, acidic and enzymatic treatments was estimated to produce 12-28 times more ethanol per unit area than the mechanically extracted juice. Complete conversion of perennial forages would meet the petroleum industry`s needs more consistently than simple extraction of soluble components. (Author)

  17. Urban Foraging: A Ubiquitous Human Practice Overlooked by Urban Planners, Policy, and Research

    Directory of Open Access Journals (Sweden)

    Charlie M. Shackleton

    2017-10-01

    Full Text Available Although hardly noticed or formally recognised, urban foraging by humans probably occurs in all urban settings around the world. We draw from research in India, South Africa, Sweden, and the United States to demonstrate the ubiquity and varied nature of urban foraging in different contexts. Across these different contexts, we distil seven themes that characterise and thereby advance thinking about research and the understanding of urban foraging. We show that it is widespread and occurs across a variety of urban spaces and places. The species used and the local practices vary between contexts, and are in constant flux as urban ecological and social settings change. This requires that urban foragers are knowledgeable about diverse species, harvest locations, and rights of access, and that their practices are adaptable to changing contexts. Despite its ubiquity, most cities have some forms of regulations that prohibit or discourage urban foraging. We highlight a few important exceptions that can provide prototypes and lessons for other cities regarding supportive policy frameworks and initiatives. The formulation of dynamic policy, design, and management strategies in support of urban foraging will benefit from understanding the common characteristics of foraging in cities worldwide, but also will require comprehension of the specific and dynamic contexts in which they would be implemented.

  18. Comparison of laboratory and field remote sensing methods to measure forage quality.

    Science.gov (United States)

    Guo, Xulin; Wilmshurst, John F; Li, Zhaoqin

    2010-09-01

    Recent research in range ecology has emphasized the importance of forage quality as a key indicator of rangeland condition. However, we lack tools to evaluate forage quality at scales appropriate for management. Using canopy reflectance data to measure forage quality has been conducted at both laboratory and field levels separately, but little work has been conducted to evaluate these methods simultaneously. The objective of this study is to find a reliable way of assessing grassland quality through measuring forage chemistry with reflectance. We studied a mixed grass ecosystem in Grasslands National Park of Canada and surrounding pastures, located in southern Saskatchewan. Spectral reflectance was collected at both in-situ field level and in the laboratory. Vegetation samples were collected at each site, sorted into the green grass portion, and then sent to a chemical company for measuring forage quality variables, including protein, lignin, ash, moisture at 135 °C, Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Total Digestible, Digestible Energy, Net Energy for Lactation, Net Energy for Maintenance, and Net Energy for Gain. Reflectance data were processed with the first derivative transformation and continuum removal method. Correlation analysis was conducted on spectral and forage quality variables. A regression model was further built to investigate the possibility of using canopy spectral measurements to predict the grassland quality. Results indicated that field level prediction of protein of mixed grass species was possible (r² = 0.63). However, the relationship between canopy reflectance and the other forage quality variables was not strong.

  19. Comparison of Laboratory and Field Remote Sensing Methods to Measure Forage Quality

    Directory of Open Access Journals (Sweden)

    Zhaoqin Li

    2010-09-01

    Full Text Available Recent research in range ecology has emphasized the importance of forage quality as a key indicator of rangeland condition. However, we lack tools to evaluate forage quality at scales appropriate for management. Using canopy reflectance data to measure forage quality has been conducted at both laboratory and field levels separately, but little work has been conducted to evaluate these methods simultaneously. The objective of this study is to find a reliable way of assessing grassland quality through measuring forage chemistry with reflectance. We studied a mixed grass ecosystem in Grasslands National Park of Canada and surrounding pastures, located in southern Saskatchewan. Spectral reflectance was collected at both in-situ field level and in the laboratory. Vegetation samples were collected at each site, sorted into the green grass portion, and then sent to a chemical company for measuring forage quality variables, including protein, lignin, ash, moisture at 135 ºC, Neutral Detergent Fiber (NDF, Acid Detergent Fiber (ADF, Total Digestible, Digestible Energy, Net Energy for Lactation, Net Energy for Maintenance, and Net Energy for Gain. Reflectance data were processed with the first derivative transformation and continuum removal method. Correlation analysis was conducted on spectral and forage quality variables. A regression model was further built to investigate the possibility of using canopy spectral measurements to predict the grassland quality. Results indicated that field level prediction of protein of mixed grass species was possible (r2 = 0.63. However, the relationship between canopy reflectance and the other forage quality variables was not strong.

  20. Produção de forragem de gramíneas anuais semeadas no verão Forage yield of annual grasses seeded on the summer

    Directory of Open Access Journals (Sweden)

    Rafael Orth

    2012-09-01

    worsen by frosts. A 2-yr split-plot experiment on randomized complete block design with three replications compared yield, yield distribution, and nutritive value in three seeding dates (January, February, and March allocated on main plots, and five forage grasses cultivars (common pearl millet, teosinte, sudangrass, and BRS 800 and AG 2501C sorghum hybrids on subplots. The two first seeding dates had the highest forage yield, about 6.0Mg ha-1 of DM than March seeding date of high nutritive value forage (>150g kg-1 MS. Sorghum-hybrids genotypes yield more than teosinte and sudangrass. Pearl millet, sudangrass and teosinte had more tillering. Pearl millet had high CP (200g kg-1 DM, and lower FDA (350g kg-1 DM concentrations on leaf blades compared to sorghums and teosinte. It is possible minimize fall forage shortage seeding annual forage grasses until end of February in the Planalto region of RS state, and extend the productive period, an additional 30 to 60-d, during a time of year when warm-season perennial grasses have low forage allowance or low nutritive value, and annual winter forages are not established.