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Sample records for sandsage-bluestem forage growth

  1. Effects of forage:concentrate ratio and forage type on apparent digestibility, ruminal fermentation, and microbial growth in goats.

    Science.gov (United States)

    Cantalapiedra-Hijar, G; Yáñez-Ruiz, D R; Martín-García, A I; Molina-Alcaide, E

    2009-02-01

    The effects of forage type and forage:concentrate ratio (F:C) on apparent nutrient digestibility, ruminal fermentation, and microbial growth were investigated in goats. A comparison between liquid (LAB) and solid (SAB)-associated bacteria to estimate microbial N flow (MNF) from urinary purine derivative excretion was also examined. Treatments were a 2 x 2 factorial arrangement of forage type (grass hay vs. alfalfa hay) and high vs. low F:C (70:30 and 30:70, respectively). Four ruminally cannulated goats were fed, at maintenance intake, 4 experimental diets according to a 4 x 4 Latin square design. High-concentrate diets resulted in greater (P diets including grass hay. Likewise, N retention, ruminal NH(3)-N concentration, and urinary excretion of purine derivatives increased (P diets based on grass hay (0.23 vs. 0.13 g of retained N/g of digested N, 30.1 vs. 12.9 mg of NH(3)-N/100 mL, and 11.5 vs. 8.40 mmol/d, respectively), but not (P > 0.05) when diets included alfalfa hay. Total protozoa numbers and holotricha proportion were greater and less (P diets. The F:C affected (P diets. Estimated MNF was strongly influenced by using either the purine bases:N ratio obtained in our experimental conditions or values reported in the literature for small ruminants. There was a F:C effect (P = 0.006) on MNF estimated from LAB but not from SAB. The effect of F:C shifting from 70:30 to 30:70 in goat diets depends on the type of forage used. The MNF measured in goats fed different diets was influenced by the bacterial pellet (LAB or SAB). In addition, the purine bases:N ratio values found were different from those reported in the literature, which underlines the need for these variables to be analyzed directly in pellets isolated from specific animals and experimental conditions.

  2. Assessment of reclaimed water irrigation on growth, yield, and water-use efficiency of forage crops

    Science.gov (United States)

    Alkhamisi, S. A.; Abdelrahman, H. A.; Ahmed, M.; Goosen, M. F. A.

    2011-09-01

    Field experiments were conducted to determine the effect of water quality (reclaimed and fresh water), water quantity, and their interactions on the growth, yield, and water use efficiency of forage maize during two winter seasons in the Arabian Gulf. The plants irrigated with the reclaimed water had higher plant height than those irrigated with the fresh water. The leaf length and leaf area (cm2) did not show any significant differences among the interaction. Reclaimed water had shorter time for 50% male and female flowering of forage maize plants, indicating earlier maturity. Plants irrigated with reclaimed water had higher chlorophyll content for all levels of water applications. A significant difference in green forage yield was found among the interactions. Reclaimed water gave the highest green forage yield of 72.12 and 59.40 t/ha at 1.4ETo and 1.0ETo, respectively. Plants irrigated with the reclaimed water used water more efficiently [3.65 kg/m3 of DM (dry matter)] than those irrigated with the fresh water [2.91 kg/m3 of DM (dry matter)] for all water quantities. The enhanced growth in wastewater-irrigated crops, compared with fresh water-irrigated crops, was attributed primarily to higher nutrient content (e.g., nitrogen) and lower salinity of the reclaimed water. The study concluded that treated wastewater irrigation increased yields of forage crops and their water use efficiency. Cost-benefit analysis, studies on the use these forage crops as animal feed, and more in depth evaluation of possible crop and soil contamination were recommended.

  3. Foraging and growth potential of juvenile Chinook Salmon after tidal restoration of a large river delta

    Science.gov (United States)

    David, Aaron T.; Ellings, Christopher; Woo, Isa; Simenstad, Charles A.; Takekawa, John Y.; Turner, Kelley L.; Smith, Ashley L.; Takekawa, Jean E.

    2014-01-01

    We evaluated whether restoring tidal flow to previously diked estuarine wetlands also restores foraging and growth opportunities for juvenile Chinook Salmon Oncorhynchus tshawytscha. Several studies have assessed the value of restored tidal wetlands for juvenile Pacific salmon Oncorhynchus spp., but few have used integrative measures of salmon performance, such as habitat-specific growth potential, to evaluate restoration. Our study took place in the Nisqually River delta, Washington, where recent dike removals restored tidal flow to 364 ha of marsh—the largest tidal marsh restoration project in the northwestern contiguous United States. We sampled fish assemblages, water temperatures, and juvenile Chinook Salmon diet composition and consumption rates in two restored and two reference tidal channels during a 3-year period after restoration; these data were used as inputs to a bioenergetics model to compare Chinook Salmon foraging performance and growth potential between the restored and reference channels. We found that foraging performance and growth potential of juvenile Chinook Salmon were similar between restored and reference tidal channels. However, Chinook Salmon densities were significantly lower in the restored channels than in the reference channels, and growth potential was more variable in the restored channels due to their more variable and warmer (2°C) water temperatures. These results indicate that some—but not all—ecosystem attributes that are important for juvenile Pacific salmon can recover rapidly after large-scale tidal marsh restoration.

  4. Effect of protein supplementation and forage allowance on the growth and reproduction of beef heifers grazing stockpiled tall fescue.

    Science.gov (United States)

    Lyons, S E; Shaeffer, A D; Drewnoski, M E; Poore, M H; Poole, D H

    2016-04-01

    Stockpiled tall fescue can provide adequate winter forage for beef cattle, although unsupplemented replacement heifers may display marginal performance before breeding. The objective of this study was to determine if protein supplementation and/or additional forage improves growth and reproductive performance of replacement heifers grazing stockpiled fescue. Cattle averaging 272 ± 1.59 kg were stratified by BW and then randomly assigned to 1 of 4 plots within a pasture replication. Treatment combinations were assigned in a 2 × 2 factorial arrangement and included 1) a conservative forage allocation ("normal," targeting 85% forage use) and mineral supplement (normal forage allocation with mineral supplement [FM]), 2) normal forage allocation with protein tub (FT), 3) more liberal forage allocation ("extra," targeting 70% forage use) and mineral supplement (extra forage allocation with mineral supplement [EM]), and 4) "extra forage allocation with protein tub (ET). Treatments were administered for 8 wk from early November to early January. Heifers were fed fescue hay for 1 wk before breeding in late January. Heifers were synchronized with the 7-d CO-Synch + controlled internal drug release device protocol and inseminated in late January. Heifers were checked for pregnancy by ultrasonography at 35 and 90 d after AI. Main and interaction effects between the 2 treatments were determined. Total supplement intake was greater for protein tub than mineral supplement (0.36 vs. 0.11 kg·heifer·d, respectively; Reproductive tract scores, pelvic area, and AI pregnancy rates were not different between treatments ( > 0.05). Overall, feeding a protein supplement or providing extra forage increased gain and interacted to increase BCS but did not have an effect on reproductive performance. Supplementing with protein and providing extra forage are strategies that can increase gain in heifers, which could aid heifers in reaching puberty before estrous synchronization.

  5. Effects of protein and energy supplementation on growth, forage intake, forage digestion and nitrogen balance in meat goat kids.

    Science.gov (United States)

    Patterson, J M; Lambert, B D; Muir, J P; Foote, A P

    2009-08-01

    The objective of this study was to further the understanding of the effects of dietary protein and energy supplements on growth, performance, feed intake and grass forage digestibility in growing meat goat wethers. In Experiment 1, an 18% CP complete goat pellet was offered alone (control diet, C) or added (+), or not, as supplement to three grass hays (coastal bermudagrass, CB; Tifton 85 bermudagrass, T; and sorghum-Sudan grass hay, SS), to Boer-cross wethers (n = 72). The resulting seven diets were offered ad libitum. In Experiment 2, four wether goats in metabolism crates were used in a 4 × 4 Latin square design and fed a SS basal diet ad libitum with treatments consisting of no supplement, supplemental urea (200 mg/kg BW daily), supplemental dextrose (0.2% BW daily), or urea + dextrose (200 mg/kg BW daily and 0.2% BW daily, respectively). In Experiment 1, average daily gain (ADG) were -3.8, -5.0 and -6.6 g/day for goats consuming CB, T and SS, respectively, and 69.2, 61.6 and 58.1 g/day for supplemented CB (CB+), T (T+) and SS (SS+), respectively, as compared to 245.8 g/day for ad libitum access to C. Supplementation in Experiment 1 increased (P diets. In Experiment 2, protein and energy supplementation increased (P diet digestibility. The beneficial effects of supplements in Experiment 1 and the increase in nitrogen retention in Experiment 2 cannot be explained by improvements in ruminal fiber utilization, but could be due to post-ruminal nutrient supply and/or increased ruminal microbial protein synthesis.

  6. Effect of Plant Growth-Promoting Bacteria on Quantitative and Qualitative Yield of Forage Maize

    Directory of Open Access Journals (Sweden)

    R. Abasi

    2016-12-01

    Full Text Available This research was conducted to investigate the effect of growth-promoting bacteria on yield and some traits of maize. This experiment was performed as a factorial randomized complete block design with three replications at research farm of Islamic Azad University, Izeh branch, Iran. The experimental factors included four strains of plant growth-promoting bacteria: Pseudomonas fluorescent 169 (B1, Pseudomonas fluorescent 79 (B2, Pseudomonas putida 108 (B3, Pseudomonas putida 159 (B4 and without bacteria (control, B5 and two corn varieties namely sc 704 (A1 and Bolson (A2. Before planting corn seeds were soaked with liquid inoculation. Plant height, number of leaves per plant and ear, forage yield, dry matter and dry matter digestibility of leaf, stem and ear, crude protein and cell wall without hemicellulose in the leaf, stem and ear were evaluated. Analysis of variances showed that the effects of varieties, bacteria and their interaction on all traits were significant. Plant height, number of leaves per plant and ear, forage yield, dry matter and stem dry matter digestibility were higher in Bolson. Moreover, dry matter digestibility of leaf and ear, crude protein and cell wall without hemicellulose in the leaf, stem and ear of sc 704 were greater, compared to hybrid Bolson. Plant height, number of leaves per plant and ear, forage yield, dry matter and dry matter digestibility of stem and ear were greater in at the presence of fluorescent strains than those of putida strains. The results revealed that bacterial inoculation enhances the grain yield, yield components and quality of forage maize. Bolson seemed potent to outperform sc 704, though this proposition needs further examination in future field trials.

  7. A day in the life of fish larvae: modeling foraging and growth using quirks.

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    Klaus B Huebert

    Full Text Available This article introduces "Quirks," a generic, individual-based model synthesizing over 40 years of empirical and theoretical insights into the foraging behavior and growth physiology of marine fish larvae. In Quirks, different types of larvae are defined by a short list of their biological traits, and all foraging and growth processes (including the effects of key environmental factors are modeled following one unified set of mechanistic rules. This approach facilitates ecologically meaningful comparisons between different species and environments. We applied Quirks to model young exogenously feeding larvae of four species: 5.5-mm European anchovy (Engraulis encrasicolus, 7-mm Atlantic cod (Gadus morhua, 13-mm Atlantic herring (Clupea harengus, and 7-mm European sprat (Sprattus sprattus. Modeled growth estimates explained the majority of variability among 53 published empirical growth estimates, and displayed very little bias: 0.65% ± 1.2% d(-1 (mean ± standard error. Prey organisms of ∼ 67% the maximum ingestible prey length were optimal for all larval types, in terms of the expected ingestion per encounter. Nevertheless, the foraging rate integrated over all favorable prey sizes was highest when smaller organisms made up >95% of the prey biomass under the assumption of constant normalized size spectrum slopes. The overall effect of turbulence was consistently negative, because its detrimental influence on prey pursuit success exceeded its beneficial influence on prey encounter rate. Model sensitivity to endogenous traits and exogenous environmental factors was measured and is discussed in depth. Quirks is free software and open source code is provided.

  8. Nutritive value of three tropical forage legumes and their influence on growth performance, carcass traits and organ weights of pigs.

    Science.gov (United States)

    Kambashi, Bienvenu; Kalala, Gaetan; Dochain, Denis; Mafwila, Jacques; Rollin, Xavier; Boudry, Christelle; Picron, Pascale; Bindelle, Jérôme

    2016-08-01

    The effects of tropical forage legumes on feed intake, growth performance and carcass traits were investigated in 16 groups of two Large White × Duroc pigs. The diets consisted of a commercial corn-soybean meal diet as the basal diet and three forage-supplemented diets. Four groups of control pigs received daily 4 % of body weight of the basal diet, and 12 groups of experimental pigs were fed the basal diet at 3.2 % of body weight completed with fresh leaves of one of the three forage legumes (Psophocarpus scandens, Stylosanthes guianensis and Vigna unguiculata) ad libitum. The study lasted 90 days. The in vitro digestion and fermentation of the forage legumes were also determined. The in vitro digestible energy content of the legumes was between 0.72 and 0.77 that of the basal diet (14.4 MJ/kg dry matter (DM)). V . unguiculata was the most digestible forage legume expected for crude protein digestibility. Feeding forage legumes lowered the dry matter intake by 4.5 to 9.6 % (P < 0.05), final body weight (P = 0.013), slaughter weight, average daily gain and hot carcass weight (P < 0.05) without affecting the feed conversion ratio (FCR), dressing percentage and back fat thickness. In conclusion, using forage to feed pig could be interesting in pig smallholder production with limited access to concentrate, as FCR was not significantly affected.

  9. Postnatal growth, age estimation and development of foraging behaviour in the fulvous fruit bat Rousettus leschenaulti

    Indian Academy of Sciences (India)

    V Elangovan; H Raghuram; E Yuvana Satya Priya; G Marimuthu

    2002-12-01

    This study documents the postnatal growth, age estimation and development of the foraging behaviour of the fulvous fruit bat Rousettus leschenaulti under captive conditions. At birth, the young were naked and pink with closed eyes and folded pinnae. By day four of age, their eyes had opened and the pups began to move. The mean length of forearm in 5-day-old pups was 24.9 mm and body mass was 10.8 g, equivalent to 32.3% and 14.2% of the values from postpartum females. The length of forearm and body mass increased linearly until 45 and 50 days, respectively, and thereafter maintained an apparent stability. The epiphyseal gap of the fourth metacarpalphalangeal joint increased until 15 days, then decreased linearly until 75 days and thereafter closed. Age was estimated quantitatively, based on linear changes observed in the length of the forearm and epiphyseal gap. Pups began to roost separately, but adjacent to their mothers when 30 days old and flew clumsily when they were about 40 days old. After attaining clumsy flight, the young bats made independent foraging attempts feebly by biting and licking small fruit pieces. Young bats were engaged in suckling as well as ingesting fruits when they were about 50 days old. Between 55 and 65 days, they flew well and fed on fruits. At the age of 75 days, the young bats were completely weaned and at two months, their foraging behaviour was similar to that of their mothers. There was no significant difference in the growth pattern of the young maintained in captivity compared with those under natural conditions.

  10. Effect of Nitrogen Application from Selected Manures on Growth, Nitrogen Uptake and Biomass Production of Cultivated Forage Rice

    Directory of Open Access Journals (Sweden)

    Gusmini Gusmini

    2015-04-01

    Full Text Available Cultivation of forage rice (Oryza sativa L. in paddy field is considered as a promising way to enhanced livestock feed supply. Pot experiment was conducted to evaluate the effects of fermented cattle and poultry manures in different levels of N application on the growth, N uptake and biomass production of forage rice. Rice cv. Tachisuzuka, Kusanohoshi and Hinohikari were grown and treated with five levels of N: 0,7,14,21, and 28 g N m-2.  The results showed that the effects of manures on plant significantly with all levels of N application. The findings indicated that in forage rice cultivation, Tachisuzuka prospects as whole crop silage (WCS because of its highest straw biomass production and suitable feed with WCS quality compared with Kusanohoshi and Hinohikari.  Application of 14 g N m-2 was considered effective for high production of Tachisuzuka forage rice and useful for the reduction of N loading of the environment.

  11. Growth of forage legumes and grasses in acidic soil amended with flue gas desulfurization products

    Energy Technology Data Exchange (ETDEWEB)

    Clark, R.B.; Baligar, V.C. [USDA ARS, Beltsville, MD (USA)

    2003-07-01

    Large amounts of flue gas desulfurization products (FGDs) are produced when SO{sub 2} emissions are trapped in the coal burning process for generation of electricity. FGDs are normally discarded instead of being reused, and reuse on soils could be important in overall management of these products. Glasshouse experiments were conducted to determine effects of various levels of three FGDs (a FGD gypsum, an oxidized FGD + Mg, and a stabilized FGD) and the control compounds CaCO{sub 3}, CaSO{sub 3}, and CaSO{sub 4} on growth of alfalfa (Medicago sativa), white clover (Trifolium repens), orchardgrass (Dactylis glomerata), tall fescue (Festuca arundinacea), switchgrass (Panicum virgatum), and eastern gamagrass (Tripsacum dactyloides) in acidic (pH 4) soil (Typic Hapludult). The FGDs enhanced growth of each plant species, with alfalfa, white clover, and tall fescue receiving greater increases than the other species, especially when grown in soil amended with FGD + Mg. FGD gypsum did not often enhance growth unless high amounts were added. FGDs containing high B and low levels of CaSO{sub 3} were detrimental to growth. Overall, FGDs improved growth responses of these forage plants grown in an infertile low pH soil.

  12. Azospirillum spp. from native forage grasses in Brazilian Pantanal floodplain: biodiversity and plant growth promotion potential.

    Science.gov (United States)

    Souza, Mayara S T; de Baura, Valter A; Santos, Sandra A; Fernandes-Júnior, Paulo Ivan; Reis Junior, Fábio B; Marques, Maria Rita; Paggi, Gecele Matos; da Silva Brasil, Marivaine

    2017-04-01

    A sustainable alternative to improve yield and the nutritive value of forage is the use of plant growth-promoting bacteria (PGPB) that release nutrients, synthesize plant hormones and protect against phytopathogens (among other mechanisms). Azospirillum genus is considered an important PGPB, due to the beneficial effects observed when inoculated in several plants. The aim of this study was to evaluate the diversity of new Azospirillum isolates and select bacteria according to the plant growth promotion ability in three forage species from the Brazilian Pantanal floodplain: Axonopus purpusii, Hymenachne amplexicaulis and Mesosetum chaseae. The identification of bacterial isolates was performed using specific primers for Azospirillum in PCR reactions and partial sequencing of the 16S rRNA and nifH genes. The isolates were evaluated in vitro considering biological nitrogen fixation (BNF) and indole-3-acetic acid (IAA) production. Based on the results of BNF and IAA, selected isolates and two reference strains were tested by inoculation. At 31 days after planting the plant height, shoot dry matter, shoot protein content and root volume were evaluated. All isolates were able to fix nitrogen and produce IAA, with values ranging from 25.86 to 51.26 mg N mL(-1) and 107-1038 µmol L(-1), respectively. The inoculation of H. amplexicaulis and A. purpusii increased root volume and shoot dry matter. There were positive effects of Azospirillum inoculation on Mesosetum chaseae regarding plant height, shoot dry matter and root volume. Isolates MAY1, MAY3 and MAY12 were considered promising for subsequent inoculation studies in field conditions.

  13. Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites.

    Science.gov (United States)

    DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Zazueta, Victor; Chambers, Mona; Hidalgo, Geoffrey; deJong, Emily Watkins

    2016-05-01

    Varroa mites are a serious pest of honey bees and the leading cause of colony losses. Varroa have relatively low reproductive rates, so populations should not increase rapidly, but often they do. Other factors might contribute to the growth of varroa populations including mite migration into colonies on foragers from other hives. We measured the proportion of foragers carrying mites on their bodies while entering and leaving hives, and determined its relationship to the growth of varroa populations in those hives at two apiary sites. We also compared the estimates of mite population growth with predictions from a varroa population dynamics model that generates estimates of mite population growth based on mite reproduction. Samples of capped brood and adult bees indicated that the proportion of brood cells infested with mites and adult bees with phoretic mites was low through the summer but increased sharply in the fall especially at site 1. The frequency of capturing foragers with mites on their bodies while entering or leaving hives also increased in the fall. The growth of varroa populations at both sites was not significantly related to our colony estimates of successful mite reproduction, but instead to the total number of foragers with mites (entering and leaving the colony). There were more foragers with mites at site 1 than site 2, and mite populations at site 1 were larger especially in the fall. The model accurately estimated phoretic mite populations and infested brood cells until November when predictions were much lower than those measured in colonies. The rapid growth of mite populations particularly in the fall being a product of mite migration rather than mite reproduction only is discussed.

  14. Growth and nutritional evaluation of napier grass hybrids as forage for ruminants

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    Brian Turano

    2016-09-01

    Full Text Available Napier grass is a perennial, tropical C-4 grass that can produce large amounts of forage. However, low temperatures and drought stress limit its productivity and nutritive value as a forage. To overcome these limitations, pearl millet × napier grass hybrids (PMN were developed. It was hypothesized that PMN hybrids were more drought-tolerant, produced higher yields, and had higher nutritive value than napier grass varieties. The yield and nutritive value of 4 napier grass varieties (Bana grass, Mott, MB4 and N51 and 4 PMN hybrids (PMN2, PMN3, 5344 and 4604 were determined with or without irrigation in a strip plot design in Hawaii. Hybrid PMN3 outperformed napier grass varieties and the other hybrids for yield, while 5344 showed higher nutritional content and digestibility than most other grasses. Dry matter yields during the 110-day study period ranged from 10.3 to 32.1 t/ha without irrigation and 19.6 to 55.8 t/ha with irrigation, indicating that moisture stress was limiting performance in raingrown pastures. Only hybrids PMN3 and PMN2 and variety MB4 showed significant growth responses to irrigation. Further work is needed to evaluate the hybrids in a range of environments over much longer periods to determine if these preliminary results can be reproduced over the long term. Similarly, feeding studies with animals are needed to determine if the in vitro data for digestibility are reflected in superior performance for the promising hybrids.Keywords: Biomass, cattle, in vitro digestion, nutrient content, Pennisetum, tropical grasses.DOI: 10.17138/TGFT(4168-178

  15. Alley cropping of legumes with grasses as forages : Effect of different grass species and row spacing of gliricidia on the growth and biomass production of forages

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    Siti Yuhaeni

    1998-12-01

    Full Text Available A study to evaluate the effect of different grass species and row spacing of gliricidia (Gliricidia sepium on the growth and biomass production of forages in an alley cropping system was conducted in two different agroclimatical zones i.e. Bogor, located at 500 m a .s .l . with an average annual rainfall of 3,112 nun/year and Sukabumi located at 900 m a .s .l . with an average annual rainfall of 1,402 mm/year . Both locations have low N, P, and K content and the soil is classified as acidic. The experimental design used was a split plot design with 3 replicates . The main plots were different grass species i.e. king grass (Pennisetum purpureum x P. typhoides and elephant grass (P. purpureum. The sub plots were the row spacing of gliricidia at 2, 3, 4, 6 m (1 hedgerows and 4 m (2 hedgerows. The results indicated that the growth and biomass production of grasses were significantly affected (P<0 .05 by the treatments in Bogor. The highest biomass productions was obtained from the 2 m row spacing which gave the highest dry matter production of grasses (1 .65 kg/hill and gliricidia (0 .086 kg/tree . In Sukabumi the growth and biomass production of grasses and gliricidia were also significantly affected by the treatments . The highest dry matter production was obtained with 2 m row spacing (dry matter of grasses and gliricidia were 1 .12 kg/hill and 0 .026 kg/tree, respectively . The result further indicated that biomass production of forages increased with the increase in gliricidia population. The alley cropping system wich is suitable for Bogor was the 2 m row spacing of gliricidia intercropped with either king or elephant grass and for Sukabumi 2 and 4 m (2 rows of gliricidia row spacing intercropped with king or elephant grass .

  16. Free-range pigs foraging on Jerusalem artichokes (Helianthus tuberosus L.) – Effect of feeding strategy on growth, feed conversion and animal behaviour

    DEFF Research Database (Denmark)

    Kongsted, Anne Grete; Horsted, Klaus; Hermansen, John Erik

    2013-01-01

    The nutritional contributions from free-range foraging, growth, feed conversion and behaviour were investigated in 36 growing pigs foraging on Jerusalem artichokes (JA) and fed concentrates restrictedly (30% of energy recommendations) or ad libitum. Compared to the ad libitum fed pigs, the pigs fed...

  17. Fermentation kinetics of two intercropped forages cut at different growth stage

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    F. Infascelli

    2010-01-01

    Full Text Available The mixture legume/grass determines agronomic advantages (i.e. lower N fertilization and more equilibrate energy/N ratio in the forage for ruminant (Betti et al., 1992. In South of Italy, the most utilized intercropped forages are barley-fava bean and vetch-oats due to the particular climatic conditions.

  18. GROWTH PERFORMANCE EVALUATION OF JUVENILES OF Archachatina marginata OVUM AND Archachatina marginata saturalis SNAIL SUBSPECIES FED FORAGES AND THEIR NUTRIENT COMPOSITION IN CROSS RIVER RAINFOREST ZONE, NIGERIA

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    J. A. UBUA

    2013-11-01

    Full Text Available The growth performance characteristics of juveniles of Archachatina marginata ovum and Archachatina marginata saturalis snail subspecies were evaluated using a feeding regime of forages. The forages of choice utilized were: Sweet potato (T1, Cocoyam (T2, Banana (T3, pawpaw (T4 and Okra (T5 respectively. The nutrient composition of these forages was equally determined. Results from this study revealed that juveniles of Archachatina marginata ovum recorded better feed intake than those of Archachatina marginata saturalis. The weight gain showed significant difference (P0.05 in Ether extract among the forages. Result of CF showed relative increase across the five forages. Banana leaves had the highest value and was significantly different (P<0.05 from those of sweet Potato and pawpaw leaves. The highest NFE content was recorded in sweet potato leaves. There was significant difference (P<0.05 in the Ash content among all the forages except sweet potato. Results from this study were within the normal proximate values of these forages and confirmed that these leaves (plant protein sources are good forages for farm animals especially micro-livestock like snails and can enhanced optimum growth characteristics.

  19. Ramet population ecology of Panicum virgatum in the field - Competitively random growth of ramets and foraging behavior of ramet populations

    Institute of Scientific and Technical Information of China (English)

    Xinguo Yang; Tianlong Wu; Xu Cheng

    2008-01-01

    The authors investigated the heterogeneous size patterns and dynamic growth of the ramet population of Panicum virgatum, a clonal caespitose plant, limited to the space occupied by a ramet bunch and the time of the ramet yearly life cycle, to understand the ecology of clonal caespitose plants in the field, where the ramet bunch generally consisted of more than one genet. Dynamic life tables for ramet populations were established by the replacement of living ramets at the present time with "dead" ones in past time. These tables revealed stable coexisting patterns of isometric and allometric growing processes of ramets in mass and height respectively, which approximately followed the historic trajectory of a density-independent population. The ecology of clonal caespitose plants is further discussed based on the competitively random growth of ramet individuals, including the scale of foraging behavior. In the field, the ramet population ecol-ogy of switchgrass may be a statistical result of competitively random growth of ramet individuals. The foraging behavior of a ramet population could then be presented as a process in which ramet individuals competed with each other for light and grew randomly, whileat the same time a relatively stable dynamic growth pattern was apparent at the level of the ramet population, and the functional leaves were placed properly in time and space.

  20. Forage growth, yield and quality responses of Napier hybrid grass cultivars to three cutting intervals in the Himalayan foothills

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    Kesang Wangchuk

    2015-09-01

    Full Text Available A 3 x 3 factorial study was conducted in the southern foothills of Bhutan to compare 3 cultivars of Napier hybrid grass (Pennisetum purpureum x P. glaucum: Pakchong-1, CO-3 and Giant Napier, at 3 cutting intervals (40, 60 and 80 days, in terms of forage growth, dry matter (DM yield and crude protein (CP concentration. The effects of cultivar x cutting interval were significant only on tiller number per plant and leaf:stem ratio (LSR. CO-3 consistently produced the highest tiller number per plant, leaves per plant and LSR, while Pakchong-1 produced the lowest. Pakchong-1 plants were taller, had bigger tillers and basal circumference and higher stem DM production than CO-3 and Giant. Leaf CP for all cultivars was about 17%, while stem CP concentration was lower for Pakchong-1 than for the other cultivars (3.6 vs. 5.3%, P<0.05. While 40-day cutting intervals produced high quality forage, yields suffered marked-ly and the best compromise between yield and quality of forage seemed to occur with 60-day cutting intervals. Pakchong-1 seems to have no marked advantages over CO-3 and Giant for livestock feed, and feeding studies would verify this. Its higher stem DM yields may be advantageous for biogas production and this aspect should be investigated.Keywords: Bhutan, CO-3, crude protein , dry matter, Giant Napier, Pakchong-1.DOI: 10.17138/TGFT(3142-150

  1. Forage growth, yield and quality responses of Napier hybrid grass cultivars to three cutting intervals in the Himalayan foothills

    Directory of Open Access Journals (Sweden)

    Kesang Wangchuk

    2015-09-01

    Full Text Available A 3 x 3 factorial study was conducted in the southern foothills of Bhutan to compare 3 cultivars of Napier hybrid grass (Pennisetum purpureum x P. glaucum: Pakchong-1, CO-3 and Giant Napier, at 3 cutting intervals (40, 60 and 80 days, in terms of forage growth, dry matter (DM yield and crude protein (CP concentration. The effects of cultivar x cutting interval were significant only on tiller number per plant and leaf:stem ratio (LSR. CO-3 consistently produced the highest tiller number per plant, leaves per plant and LSR, while Pakchong-1 produced the lowest. Pakchong-1 plants were taller, had bigger tillers and basal circumference and higher stem DM production than CO-3 and Giant. Leaf CP for all cultivars was about 17%, while stem CP concentration was lower for Pakchong-1 than for the other cultivars (3.6 vs. 5.3%, P<0.05. While 40-day cutting intervals produced high quality forage, yields suffered marked-ly and the best compromise between yield and quality of forage seemed to occur with 60-day cutting intervals. Pakchong-1 seems to have no marked advantages over CO-3 and Giant for livestock feed, and feeding studies would verify this. Its higher stem DM yields may be advantageous for biogas production and this aspect should be investigated.Keywords: Bhutan, CO-3, crude protein , dry matter, Giant Napier, Pakchong-1.DOI: 10.17138/TGFT(3142-150

  2. Effects of feeding green forage of sulla (Hedysarum coronarium L.) on lamb growth and carcass and meat quality.

    Science.gov (United States)

    Bonanno, A; Di Miceli, G; Di Grigoli, A; Frenda, A S; Tornambè, G; Giambalvo, D; Amato, G

    2011-01-01

    The nutritional effects of sulla (Hedysarum coronarium L.) forage containing condensed tannins (CT) on growth of lambs, and carcass and meat quality were investigated. Thirty-two male Comisana lambs aged 100 ± 8 days weighing 19.0 ± 2.8 kg were fed fresh forage of sulla or CT-free annual ryegrass (Lolium multiflorum Lam. subsp. Wersterwoldicum) for 49 days until slaughter; in addition, each lamb was supplied with 200 g/days of concentrate. Eight lambs per diet had been previously treated with anthelmintic drugs to remove nematode parasites. Measurements of BW and feed intake, and counts of faecal nematode eggs were made. Carcass parameters were recorded after slaughter, and tissue components of the hind leg were determined. Longissimus dorsi meat was evaluated for pH, colour, thawing and cooking losses, Warner-Bratzler shear force, chemical composition and sensory properties based on triangle tests. Relative to ryegrass-fed lambs, sulla-fed lambs had significantly greater dry matter (DM) and protein intake, a more favourable feed conversion ratio, and superior growth rate, final BW at 150 days of age, carcass weight, yield and fatness. These results were attributed to the high protein and non-structural carbohydrate content of sulla, and also to the moderate CT content of sulla (16.7 and 20.3 g/kg of DM in offered and consumed sulla forage, respectively). Anthelmintic treatment did not affect lamb growth, as the level of parasitic infection (initial and final) was low. The physical, chemical and sensory properties of the lamb meat were not influenced by diet.

  3. Forage growth, yield and quality responses of Napier hybrid grass cultivars to three cutting intervals in the Himalayan foothills

    OpenAIRE

    2015-01-01

    A 3 x 3 factorial study was conducted in the southern foothills of Bhutan to compare 3 cultivars of Napier hybrid grass (Pennisetum purpureum x P. glaucum: Pakchong-1, CO-3 and Giant Napier), at 3 cutting intervals (40, 60 and 80 days), in terms of forage growth, dry matter (DM) yield and crude protein (CP) concentration. The effects of cultivar x cutting interval were significant only on tiller number per plant and leaf:stem ratio (LSR). CO-3 consistently produced the highest tiller number p...

  4. Growth performance, feeding behavior, and selected blood metabolites of Holstein dairy calves fed restricted amounts of milk: No interactions between sources of finely ground grain and forage provision.

    Science.gov (United States)

    Mirzaei, M; Khorvash, M; Ghorbani, G R; Kazemi-Bonchenari, M; Ghaffari, M H

    2017-02-01

    The objective of this study was to investigate the effects of grain sources and forage provision on growth performance, blood metabolites, and feeding behaviors of dairy calves. Sixty 3-d-old Holstein dairy calves (42.2 ± 2.5 kg of body weight) were used in a 2 × 3 factorial arrangement with the factors being grain sources (barley and corn) and forage provision (no forage, alfalfa hay, and corn silage). Individually housed calves were randomly assigned (n = 10 calves per treatment: 5 males and 5 females) to 6 treatments: (1) barley grain (BG) without forage supplement, (2) BG with alfalfa hay (AH) supplementation, (3) BG with corn silage (CS) supplementation, (4) corn grain (CG) without forage supplement, (5) CG with AH supplementation, and (6) CG with CS supplementation. All calves had ad libitum access to water and starter feed throughout the experiment. All calves were weaned on d 49 and remained in the study until d 63. Starter feed intake and average daily gain (ADG) was greater for calves fed barley than those fed corn during the preweaning and overall periods. Calves supplemented with CS had greater final body weight and postweaning as well as overall starter feed intake than AH and non-forage-supplemented calves. During the preweaning and overall periods, feeding of CS was found to increase ADG compared with feeding AH and nonforage diets. However, feed efficiency was not affected by dietary treatments. Calves supplemented with CS spent more time ruminating compared with AH and control groups; nonnutritive oral behaviors were the greatest in non-forage-supplemented calves. Regardless of the grain sources, the rumen pH value was greater for AH calves compared with CS and non-forage-supplemented calves. Blood concentration of BHB was greater for CS-supplemented calves compared with AH and non-forage-supplemented calves. Furthermore, body length and heart girth were greater for calves fed barley compared with those fed corn, and also in forage

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

    Directory of Open Access Journals (Sweden)

    Patrícia Carneiro Souto

    2010-06-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  7. Effects of grass forage species and long-term period of low quality forage diet feeding on growth performance, nutrient utilization and microbial nitrogen yield in growing wether lambs.

    Science.gov (United States)

    Kim, Da-Hye; Choi, Ki-Choon; Song, Sang-Houn; Ichinohe, Toshiyoshi

    2016-02-01

    Six growing lambs were used to evaluate the feeding value of two forage-based diets in a long-term feeding period by measuring body weight (BW) gain, digestibility, nitrogen (N) retention and microbial N (MBN) yield. The animals were fed imported low-quality timothy hay (TH) with concentrate diet (THD) or imported low-quality Italian ryegrass straw (IR) with concentrate diet (IRD) for 9 months. The forages were offered at 2% BW, and concentrate was fed at 40% of forage intake. The BW gain averaged 82.6 and 66.2 g/day for THD and IRD, respectively, without showing significant difference. Average forage intake (% BW) was significantly greater for IR than for TH, although it was not affected by feeding periods. The digestibility did not differ between diets or periods. The numerically greater (P = 0.06) ratio of retained N to absorbed N for IRD than that for THD was prominent. Neither diet nor period had significant effect on MBN supply and efficiency of MBN synthesis. The results suggest that the IR-based diet can be also used for long-term periods of feeding to growing ruminant animals as a grass hay-based diet without any detrimental effects on nutrient utilization and growth performance.

  8. Dietary forage concentration and particle size affect sorting, feeding behaviour, intake and growth of Chinese Holstein male calves.

    Science.gov (United States)

    Muhammad, A U R; Xia, C Q; Cao, B H

    2016-04-01

    The objective of study was to evaluate the effect of forage concentration (F:C) and forage particle length (FPL) on sorting, feeding behaviour, intake, growth and body measurements of growing calves. Twenty-eight weaned calves of body weight 156.79 ± 33.44 (mean ± SD) were used in 2 × 2 factorial arrangements with the factors FPL of hay grass (full and short) and hay grass concentrations (low, 50% and high, 65%). The treatments were as follows: full length (FL) with low F:C (50:50), FL with high F:C(65:35), short length (SL) with low F:C (50:50) and SL with high F:C (65:35). Increasing F:C and decreasing FPL enhanced sorting for short and fine particle and sorting against long particle (p behaviour, interaction for eating time and eating time per kilogram DM was present. Increasing the F:C increased the eating time in both FL and SL (p behaviour (p behaviour.

  9. Genome-Wide association mapping of loci associated with plant growth and forage production under salt stress in alfalfa (Medicago sativa L.)

    Science.gov (United States)

    Salinity tolerance is highly desirable to sustain alfalfa production in marginal lands that have been rendered saline. In this study, we used a diverse panel of alfalfa accessions for mapping loci associated with plant growth and forage production under salt stress using genome-wide association stud...

  10. Growth performance and total tract nutrient digestion for Holstein heifers limit-fed diets high in distillers grains with different forage particle size

    Science.gov (United States)

    This study evaluated dairy heifer growth performance and total tract nutrient digestion when fed diets high in dried distillers grains with solubles (DDGS) with different forage particle size. An 8-wk randomized complete block design study was conducted utilizing twenty-two Holstein heifers (123 ±...

  11. Risky business for a juvenile marine predator? Testing the influence of foraging strategies on size and growth rate under natural conditions.

    Science.gov (United States)

    Hussey, Nigel E; DiBattista, Joseph D; Moore, Jonathan W; Ward, Eric J; Fisk, Aaron T; Kessel, Steven; Guttridge, Tristan L; Feldheim, Kevin A; Franks, Bryan R; Gruber, Samuel H; Weideli, Ornella C; Chapman, Demian D

    2017-04-12

    Mechanisms driving selection of body size and growth rate in wild marine vertebrates are poorly understood, thus limiting knowledge of their fitness costs at ecological, physiological and genetic scales. Here, we indirectly tested whether selection for size-related traits of juvenile sharks that inhabit a nursery hosting two dichotomous habitats, protected mangroves (low predation risk) and exposed seagrass beds (high predation risk), is influenced by their foraging behaviour. Juvenile sharks displayed a continuum of foraging strategies between mangrove and seagrass areas, with some individuals preferentially feeding in one habitat over another. Foraging habitat was correlated with growth rate, whereby slower growing, smaller individuals fed predominantly in sheltered mangroves, whereas larger, faster growing animals fed over exposed seagrass. Concomitantly, tracked juveniles undertook variable movement behaviours across both the low and high predation risk habitat. These data provide supporting evidence for the hypothesis that directional selection favouring smaller size and slower growth rate, both heritable traits in this shark population, may be driven by variability in foraging behaviour and predation risk. Such evolutionary pathways may be critical to adaptation within predator-driven marine ecosystems. © 2017 The Author(s).

  12. EFFECT OF MULCH AND MIXED CROPPING GRASS - LEGUME AT SALINE SOIL ON GROWTH, FORAGE YIELD AND NUTRITIONAL QUALITY OF GUINEA GRASS

    Directory of Open Access Journals (Sweden)

    F. Kusmiyati

    2014-10-01

    Full Text Available The research was conducted to evaluate the effect of mulch and mixed cropping grass – legume atsaline soil on growth, forage yield and nutritional quality of guinea grass. Saline soil used in thisresearch was classified into strongly saline soil with low soil fertility. The research was arrranged inrandomized complete block design with 3 blocks. The treatments were : M1 = guinea grassmonoculture, without mulch; M2 = guinea grass monoculture, 3 ton/ha mulch; M3 = guinea grassmonoculture, 6 ton/ha mulch, M4 = mixed cropping grass with Sesbania grandiflora, without mulch;M5 = mixed cropping grass with Sesbania grandiflora, 3 ton/ha mulch; M6 = mixed cropping grass withSesbania grandiflora, 6 ton/ha mulch. Data were analyzed using analysis of variance, then followed byDuncan's Multiple Range Test. The highest soil moisture content was achieved at mixed cropping grasslegumewith 6 ton/ha of mulch. The effect of mulch at saline soil significantly increased plant growth,forage yield and nutritional quality of guinea grass. Application of 3 ton/ha mulch increased plantgrowth, forage yield and nutritional quality of guinea grass. Plant growth, forage yield and nutritionalquality of guinea grass were not affected by monoculture or mixed cropping with Sesbania at saline soil.

  13. EFFECT OF GROWTH STAGES AND RANGE SYSTEMS ON VEGETATION ATTRIBUTES, CARRYING CAPACITY, STOCKING RATE AND FORAGE PRODUCTIVITY, NORTH KORDOFAN, SUDAN

    Directory of Open Access Journals (Sweden)

    Abdel Moniem M.A. El hag

    2012-03-01

    Full Text Available The range vegetation attributes, carrying capacity, stocking rates and forage productivity were studied in close and open range systems at the flowering and seed setting stages during the September and November 2010, respectively, in El Rosa (El-khuwei locality. Sampling was done by locating 2Km2 in close and open range systems in a radiating manner from the centre of each site. Completely Randomized Design (CRD was used to analyses treatments. Biomass production of plants and plant cover at the flowering stage in the close range system were significantly (P<0.0001 higher than that at the seed setting stage in the open range system. The plant density was significant (P<0.05 higher in the close rang system at the flowering stage and lower at the seed setting stage in the open range system. Bare soil and litter was significantly higher (P<0.0001 in the open range system during the seed setting stage and lower in the close range system during the flowering stage. Forage productivity of plants and shrubs browse kg/ha on rangeland was significantly higher (P<0.05 in the close range system during the flowering stage and lower in open range system at the seed setting stage. Carrying capacity was significantly higher (P<0.0001 in the close range system at the seed setting stage and lower in the open range at the flowering stage. Stoking rates in open range system during the seed setting stage was significantly higher (P<0.0001 and lower in the close range system during the seed setting stage. The frequencies of Huskneet (Cenchrus biflorus, Bano, (Eragrostis tremula, Difra (Echinocloa colonum, leflef Luffa aegyptiaca, Gaw (Aristida sp, Shuleny Zornia glochidiata and Aborakhus Andropogon gayanus were higher in close system during the two stages of growth. Plants such as Abodaib Ceraotheca sesamoid, Bigual Blepharis linarifolia, Tmrfar (Oldenlandia senegalensis, Rabaa (Zalea sp, Himeira Hymerocardia, Diresa (Tribulus terrestris and Huntot Merremia pinnata

  14. Magnesium Fertilizer-Induced Increase of Symbiotic Microorganisms Improves Forage Growth and Quality.

    Science.gov (United States)

    Chen, Jihui; Li, Yanpeng; Wen, Shilin; Rosanoff, Andrea; Yang, Gaowen; Sun, Xiao

    2017-04-26

    Magnesium (Mg) plays important roles in photosynthesis and protein synthesis; however, latent Mg deficiencies are common phenomena that can influence food quality. Nevertheless, the effects of Mg fertilizer additions on plant carbon (C):nitrogen (N):phosphorus (P) stoichiometry, an important index of food quality, are unclear and the underlying mechanisms unexplored. We conducted a greenhouse experiment using low-Mg in situ soil without and with a gradient of Mg additions to investigate the effect of Mg fertilizer on growth and stoichiometry of maize and soybean and also measure these plants' main symbiotic microorganisms: arbuscular mycorrhizal fungi (AMF) and rhizobium, respectively. Our results showed that Mg addition significantly improved both plant species' growth and also increased N and P concentrations in soybean and maize, respectively, resulting in low C:N ratio and high N:P ratio in soybean and low C:P and N:P ratios in maize. These results presumably stemmed from the increase of nutrients supplied by activation-enhanced plant symbiotic microorganisms, an explanation supported by statistically significant positive correlations between plant stoichiometry and plants' symbiotic microorganisms' increased growth with Mg addition. We conclude that Mg supply can improve plant growth and alter plant stoichiometry via enhanced activity of plant symbiotic microorganisms. Possible mechanisms underlying this positive plant-soil feedback include an enhanced photosynthetic product flow to roots caused by adequate Mg supply.

  15. Investigating the impacts of field-realistic exposure to a neonicotinoid pesticide on bumblebee foraging, homing ability and colony growth.

    Science.gov (United States)

    Stanley, Dara A; Russell, Avery L; Morrison, Sarah J; Rogers, Catherine; Raine, Nigel E

    2016-10-01

    The ability to forage and return home is essential to the success of bees as both foragers and pollinators. Pesticide exposure may cause behavioural changes that interfere with these processes, with consequences for colony persistence and delivery of pollination services.We investigated the impact of chronic exposure (5-43 days) to field-realistic levels of a neonicotinoid insecticide (2·4 ppb thiamethoxam) on foraging ability, homing success and colony size using radio frequency identification (RFID) technology in free-flying bumblebee colonies.Individual foragers from pesticide-exposed colonies carried out longer foraging bouts than untreated controls (68 vs. 55 min). Pesticide-exposed bees also brought back pollen less frequently than controls indicating reduced foraging performance.A higher proportion of bees from pesticide-exposed colonies returned when released 1 km from their nests; this is potentially related to increased orientation experience during longer foraging bouts. We measured no impact of pesticide exposure on homing ability for bees released from 2 km, or when data were analysed overall.Despite a trend for control colonies to produce more new workers earlier, we found no overall impacts of pesticide exposure on whole colony size. Synthesis and applications. This study shows that field-realistic neonicotinoid exposure can have impacts on both foraging ability and homing success of bumblebees, with implications for the success of bumblebee colonies in agricultural landscapes and their ability to deliver crucial pollination services. Pesticide risk assessments should include bee species other than honeybees and assess a range of behaviours to elucidate the impact of sublethal effects. This has relevance for reviews of neonicotinoid risk assessment and usage policy world-wide.

  16. Fall growth, nutritive value, and estimation of total digestible nutrients for cereal-grain forages in the north-central United States.

    Science.gov (United States)

    Coblentz, W K; Walgenbach, R P

    2010-01-01

    Throughout the Southern Great Plains, wheat is managed frequently as a dual-purpose crop, but this production paradigm is not necessarily applicable throughout other regions of the United States, and a wider array of management options can be considered for forage-only uses of cereal grains. Our objectives were to assess the fall-growth potential of wheat (Triticum aestivum L.), triticale (X Triticosecale Wittmack), and oat (Avena sativa L.) cultivars in Wisconsin, and then to further evaluate and compare the fiber composition and TDN of these fall-grown forages. For 2006, yields of DM for all cultivars increased quadratically (P or = 0.072), including forage-type oat. Although TDN estimates generally were relatively static across harvest dates, the concentrations of truly digestible components constituting the total TDN pool were quite fluid. Generally, reductions of truly digestible CP were offset by increases in truly digestible nonfiber carbohydrate, truly digestible fiber, or both. The relatively stable energy densities for cereal-grain cultivars observed across harvest dates suggest that a broad window of opportunity exists for usage, including a single harvest as silage.

  17. Changes in feed intake, growth, feed efficiency, and body composition of beef cattle fed forage then concentrate diets

    Science.gov (United States)

    The objective of this experiment was to determine changes in production traits and body composition of beef steers and heifers when fed a forage-based ration followed by a concentrate-based ration. Cattle were progeny of composite breed cows bred to Charolais, Simmental, and Red Angus bulls. Appro...

  18. Population Growth of Varroa destructor (Acari: Varroidae) in Colonies of Russian and Unselected Honey Bee (Hymenoptera: Apidae) Stocks as Related to Numbers of Foragers With Mites.

    Science.gov (United States)

    DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Danka, Robert; Chambers, Mona; DeJong, Emily Watkins; Hidalgo, Geoff

    2017-06-01

    Varroa (Varroa destructor Anderson and Trueman) is an external parasite of honey bees (Apis mellifera L.) and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite-resistant stocks such as the Russian honey bee (RHB) also are available. Russian honey bee and other mite-resistant stocks limit Varroa population growth by affecting factors that contribute to mite reproduction. However, mite population growth is not entirely due to reproduction. Numbers of foragers with mites (FWM) entering and leaving hives also affect the growth of mite populations. If FWM significantly contribute to Varroa population growth, mite numbers in RHB colonies might not differ from unselected lines (USL). Foragers with mites were monitored at the entrances of RHB and USL hives from August to November, 2015, at two apiary sites. At site 1, RHB colonies had fewer FWM than USL and smaller phoretic mite populations. Russian honey bee also had fewer infested brood cells and lower percentages with Varroa offspring than USL. At site 2, FWM did not differ between RHB and USL, and phoretic mite populations were not significantly different. At both sites, there were sharp increases in phoretic mite populations from September to November that corresponded with increasing numbers of FWM. Under conditions where FWM populations are similar between RHB and USL, attributes that contribute to mite resistance in RHB may not keep Varroa population levels below that of USL. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

  19. Substitution of corn and soybean with green banana fruits and Gliricidia sepium forage in sheep fed hay-based diets: effects on intake, digestion and growth.

    Science.gov (United States)

    Archimède, H; González-García, E; Despois, P; Etienne, T; Alexandre, G

    2010-02-01

    This study aimed to evaluate the substitution of imported corn and soybean by local feed resources from tropical production settings such as entire green banana and Gliricidia sepium forage as energy and protein sources, respectively, in sheep diets. Two experiments were conducted: first, a 'growth trial' and second, an in vivo digestion study. In the 'growth trial', 40 Martinik lambs [body weight (BW): 29.4 +/- 3.6 kg; 6 months old) were used and distributed into four groups of 10 lambs each according to treatment: HBGl (banana + gliricidia at low level; 1500 g/day; 119 g/kg BW(0.75)), HBGh (banana + gliricidia at high level; 3000 g/day; 238 g/kg BW(0.75)), HBS (banana + soybean cake) and Control (corn + soybean cake). In digestion trial, four Martinik rams (BW: 57.2 +/- 3.45 kg) fitted with ruminal and duodenal cannulae were used; treatments (HBG, HBS and Control) were similar but adjusted to metabolic body weight (MW) and just one level of gliricidia was used. Intake, average daily gain (ADG), feed intake to gain index (F:G), apparent total and ruminal digestibilities as well as nitrogen balance, microbial efficiency and volatile fatty acid (VFA) profile were monitored. Lambs fed HBGh had greater dry matter (DM) intake based on MW and ADG (173 g/day vs. 141 g/day; p banana or corn + soybean cake (687 g/kg DM and 658 g/kg DM, respectively). Ruminal DM and OM digestibilities did not differ among treatments. Total or individual VFA concentrations were also not influenced by the diet. Higher (p = 0.006) ruminal fluid pH values were recorded for diets combining banana and gliricidia (6.54) or banana and soybean (6.39) until 3 h after a meal. As all animals on gliricidia- and banana-supplemented diets gained weight and maintained a positive N balance, it is concluded that green banana and gliricidia forage may be a viable alternative to replace conventional energy and protein supplements in sheep diets.

  20. Effects of high-sulfur water and clinoptilolite on health and growth performance of steers fed forage-based diets.

    Science.gov (United States)

    Cammack, K M; Wright, C L; Austin, K J; Johnson, P S; Cockrum, R R; Kessler, K L; Olson, K C

    2010-05-01

    Sulfur-induced polioencephalomalacia (sPEM), a neurological disorder affecting ruminants, is associated with consumption of diets with increased S (high-S). High-S water is commonly found in many western states and is a major source of dietary S for grazing cattle. Consumption of high-S water has been associated with sPEM and decreased performance. Identification of a feed supplement that would counteract the negative effects of high-S water would decrease the incidence of sPEM and prevent performance reductions in regions with problematic water sources. The objectives of this study were to 1) determine the effects of administering high-S drinking water to forage-fed feedlot steers on health and performance, and 2) determine the effectiveness of clinoptilolite, a clay mineral with increased cation-exchange capacity, in negating the effects of high-S drinking water. Yearling steers (n = 96; 318.2 +/- 2.1 kg of BW) were randomly assigned to 1 of 4 treatments for a 77-d trial period: control with low-S water (566 mg of SO(4)/L), high-S water (3,651 mg of SO(4)/L), or high-S water plus clinoptilolite supplemented at 2.5 or 5.0% of the diet DM. Feed and water consumption were measured daily, and all steers were weighed on d -2, -1, 29, 53, 76, and 77. Plasma samples were collected on d 0, 58, and 77, and liver samples on d 0 and 77. There was a greater (P treatment groups. In total, 12 cases of sPEM were confirmed by the presence of cortical lesions in steers consuming high-S water. Daily DMI (P = 0.002) and daily water intake (P = 0.001) were less in high-S water steers than control steers. No differences (P >or= 0.546) in ADG or G:F were observed. Plasma Cu decreased (P = 0.029) to a greater magnitude in high-S water steers than the control steers over the 77-d trial period. Mineral analyses of hepatic tissue from randomly selected healthy steers from each treatment group (n = 10 per treatment) showed an interaction (P treatment for Cu, Se, and Zn concentrations

  1. Genome-Wide Association Mapping of Loci Associated with Plant Growth and Forage Production under Salt Stress in Alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Liu, Xiang-Ping; Yu, Long-Xi

    2017-01-01

    Salinity tolerance is highly desirable to sustain alfalfa production in marginal lands that have been rendered saline. In this study, we used a diverse panel of 198 alfalfa accessions for mapping loci associated with plant growth and forage production under salt stress using genome-wide association studies (GWAS). The plants were genotyped using genotyping-by-sequencing (GBS). A greenhouse procedure was used for phenotyping four agronomic and physiological traits affected by salt stress, including dry weight (DW), plant height (PH), leaf chlorophyll content (LCC), and stomatal conductance (SC). For each trait, a stress susceptibility index (SSI) was used to evaluate plant performance under stressed and non-stressed conditions. Marker-trait association identified a total of 42 markers significantly associated with salt tolerance. They were located on all chromosomes except chromosome 2 based on the alignment of their flanking sequences to the reference genome (Medicago truncatula). Of those identified, 13 were associated with multiple traits. Several loci identified in the present study were also identified in previous reports. BLAST search revealed that 19 putative candidate genes linked to 24 significant markers. Among them, B3 DNA-binding protein, Thiaminepyrophosphokinase and IQ calmodulin-binding motif protein were identified among multiple traits in the present and previous studies. With further investigation, these markers and candidates would be useful for developing markers for marker-assisted selection in breeding programs to improve alfalfa cultivars with enhanced tolerance to salt stress.

  2. Genome-Wide Association Mapping of Loci Associated with Plant Growth and Forage Production under Salt Stress in Alfalfa (Medicago sativa L.

    Directory of Open Access Journals (Sweden)

    Xiang-Ping Liu

    2017-05-01

    Full Text Available Salinity tolerance is highly desirable to sustain alfalfa production in marginal lands that have been rendered saline. In this study, we used a diverse panel of 198 alfalfa accessions for mapping loci associated with plant growth and forage production under salt stress using genome-wide association studies (GWAS. The plants were genotyped using genotyping-by-sequencing (GBS. A greenhouse procedure was used for phenotyping four agronomic and physiological traits affected by salt stress, including dry weight (DW, plant height (PH, leaf chlorophyll content (LCC, and stomatal conductance (SC. For each trait, a stress susceptibility index (SSI was used to evaluate plant performance under stressed and non-stressed conditions. Marker-trait association identified a total of 42 markers significantly associated with salt tolerance. They were located on all chromosomes except chromosome 2 based on the alignment of their flanking sequences to the reference genome (Medicago truncatula. Of those identified, 13 were associated with multiple traits. Several loci identified in the present study were also identified in previous reports. BLAST search revealed that 19 putative candidate genes linked to 24 significant markers. Among them, B3 DNA-binding protein, Thiaminepyrophosphokinase and IQ calmodulin-binding motif protein were identified among multiple traits in the present and previous studies. With further investigation, these markers and candidates would be useful for developing markers for marker-assisted selection in breeding programs to improve alfalfa cultivars with enhanced tolerance to salt stress.

  3. Partial or total replacement of commercial concentrate with on-farm-grown mulberry forage: effects on lamb growth and feeding costs.

    Science.gov (United States)

    Alpízar-Naranjo, A; Arece-García, J; Esperance, M; López, Y; Molina, M; González-García, E

    2017-03-01

    Replacing commercial concentrate with mulberry foliage was evaluated in a feeding trial lasting 126 days. Forty-eight weaned male Pelibuey lambs (20.6 ± 0.80 kg of BW) were randomly allocated to four groups: (1) supplementing the basal diet with mulberry at 1% (DM basis; M-1), (2) mulberry at 0.75% plus 0.1 kg concentrate fresh matter basis (M-0.75), (3) mulberry at 0.50% plus 0.2 kg concentrate (M-0.50) and (4) basal diet plus 0.3 kg concentrate (control; M-0). During the first 90 days, the basal diet was Pennisetum purpureum forage which was substituted by a mixture of guinea grass and sugarcane from 90 days. Average daily gain (ADG, g/day), dry matter intake (DMI) and feed conversion rate (FCR; DMI/ADG) were determined. The ADG was affected (P < 0.01) by the diet, with the lowest obtained in M-1 lambs (71 ± 6.4 g/day), whereas no differences among the other groups were observed (94 ± 6.4 g DM/lamb). The DMI was higher (P < 0.01) in M-0 (937 g DM/lamb) which concomitantly affected differences in FCR (11.9, 9.9, 10.5 and 9.7 kg DMI/kg BW gain for M-1, M-0.75, M-0.50 and M-0 lambs, respectively). Final BW at slaughtering and hot or cold carcass yields were coherent with growth rate findings. Biological yield (cold carcass weight/empty BW) was higher (P < 0.01) in M-0.75. Without compromising animal productivity, replacing imported concentrate with mulberry reduced the feeding cost. Optimum results were obtained with M-75 diet. Further studies must be conducted for optimizing energy/protein ratios with different ingredients while increasing DMI and lamb growth rates in this tropical genotype.

  4. Simulation of water-limited growth of the forage shrub saltbush (Atriplex nummularia Lindl.) in a low-rainfall environment of southern Australia

    NARCIS (Netherlands)

    Descheemaeker, K.K.E.; Smith, A.P.; Robertson, M.J.; Whitbread, A.; Huth, N.I.; Davoren, W.; Emms, J.; Llewellyn, R.

    2014-01-01

    Old man saltbush (Atriplex nummularia Lindl.) is a useful forage shrub for livestock in the low-rainfall areas of the world, and particularly in Australia. In these semi-arid and arid environments, saltbush is valuable for increasing the production from otherwise marginal areas of the farm and durin

  5. Corn in consortium with forages

    Directory of Open Access Journals (Sweden)

    Cássia Maria de Paula Garcia

    2013-12-01

    and Urochloa, there were no differences between treatments, even with higher averages in the consortium when compared with single corn. Regarding the dry mass production (DMP of forages, the consortium CMD had the highest average yield; however, it did not differ significantly of consortiums CBD and CRD. Already the consortium CTD submitted the lowest DMP, but also did not differ significantly from consortia CBD and CRD. The corn intercropped with forages of the genus Panicum and Urochloa did not influence growth and grain yield of irrigated corn no-tillage system in the savannah.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-01-01

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

  7. Crescimento e produtividade do sorgo forrageiro BR 601 sob adubação verde Growth and yield of forage sorghum cv. BR 601 under green manure

    Directory of Open Access Journals (Sweden)

    Romeu C. Andrade Neto

    2010-02-01

    Full Text Available O efeito da adubação verde sobre o crescimento e a produtividade do sorgo forrageiro BR 601, foi estudado em experimento desenvolvido na UFERSA, em Mossoró, RN, no qual o delineamento utilizado foi em blocos casualizados completos, em esquema de parcelas subdivididas no tempo com três repetições. Testaram-se sete espécies de leguminosas, Mucuna aterrima, Canavalia ensiformis, Cajanus cajan, Dolichos lab-lab, Crotalaria juncea, Crotalaria spectabilis e Vigna unguiculata, uma mistura das leguminosas mais milho, sorgo e girassol, e a vegetação espontânea, como testemunha. Determinaram-se, para cada tratamento, a quantidade de massa verde, massa seca e teores de N, P, K, Na, Ca e Mg da parte aérea, a partir dos quais foi calculada a quantidade de nutrientes acumulada por hectare. As quantidades de matéria fresca e seca da parte aérea, altura de plantas e número de folhas do sorgo semeado após a incorporação dos adubos verdes, foram avaliadas aos 20, 40, 60, 80 e 100 dias após o plantio. A Mucuna aterrima mostrou-se a melhor opção como adubo verde em virtude de proporcionar os maiores valores das características avaliadas ao final do ciclo do sorgo podendo-se, também, recomendar a Crotalaria juncea e o Dolichos lab-lab, o qual apresentou a maior massa seca e quantidade de nutrientes na parte aérea.The effect of green manure on growth and yield of forage sorghum BR 601 was studied in a trial carried out at the UFERSA, Mossoró, RN, Brazil. The experimental design was completely randomized blocks in a scheme of split plots in time, with three replications. Treatments tested were seven legume species, Mucuna aterrima, Canavalia ensiformis, Cajanus cajan, Dolichos lab-lab, Crotalaria juncea, Crotalaria spectabilis, and Vigna unguiculata, a mixture of the legumes plus corn, sorghum and sunflower, and spontaneous vegetation as a control. For each treatment the amount of fresh mass, dry mass and contents of N, P, K, Na, Ca and Mg in

  8. Foraging Experiences with Children

    Science.gov (United States)

    Russell, Helen Ross

    1976-01-01

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

  9. 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.

  10. 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.

  11. 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.

  12. Redesigning forages with condensed tannins

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2016-08-01

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

  14. 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…

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

    Science.gov (United States)

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

    2014-03-01

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

  16. Effect of forage type, harvesting time and exogenous enzyme application on degradation characteristics measured using in vitro technique

    DEFF Research Database (Denmark)

    Moharrery, Ali; Hvelplund, Torben; Weisbjerg, Martin Riis

    2009-01-01

    /kg for aNDFom. For aNDFom, legumes generally had lower potential degradability and longer lag times than grasses. The effective degradability of aNDFom for forage harvested in spring growth was considerably higher than for the same forage harvested in second re-growth. Addition of the E1 and E2 to forage......Five forage species cut at different harvest times were studied for their degradation characteristics using in vitro digestibility technique. The forage species were two grasses and three legumes growing in two seasons (spring growth and second re-growth). Grass and legume forages were harvested...... at three harvesting times being early (E), middle (M) and late (L), both during the spring growth and the second re-growth. The grasses included perennial ryegrass (Lolium perenne), and festulolium (XFestulolium), and the legumes included white clover (Trifolium repens), red clover (Trifolium pratense...

  17. The Dynamics of Foraging Ants

    Science.gov (United States)

    Baxter, G. William

    2009-03-01

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

  18. Collective foraging in heterogeneous landscapes

    CERN Document Server

    Bhattacharya, Kunal

    2013-01-01

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

  19. 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.

  20. Population growth of Varroa destructor (Acari: Varroidae) in colonies of Russian and unselected honey bee (Hymenoptera: Apidae) stock as related to numbers of foragers with mites

    Science.gov (United States)

    Varroa mites are an external parasite of honey bees and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite resistant stocks such as the Russian honey bee (RHB) also are available. RHB and other mite resistant stock limit Varroa population growth...

  1. Breeding tropical forages

    Directory of Open Access Journals (Sweden)

    L Jank

    2011-01-01

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

  2. 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.

  3. Spatial memory in foraging games.

    Science.gov (United States)

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

    2016-03-01

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

  4. Root Foraging Performance and Life-History Traits.

    Science.gov (United States)

    Weiser, Martin; Koubek, Tomáš; Herben, Tomáš

    2016-01-01

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

  5. Flooding tolerance of forage legumes.

    Science.gov (United States)

    Striker, Gustavo G; Colmer, Timothy D

    2016-06-20

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

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

    Directory of Open Access Journals (Sweden)

    Michael E. Ruckle

    2017-02-01

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

  7. Foraging behavior and physiological changes in precocial quail chicks in response to low temperatures

    NARCIS (Netherlands)

    Krijgsveld, KL; Visser, GH; Daan, S

    2003-01-01

    We examined whether low ambient temperatures influence foraging behavior of precocial Japanese quail chicks and alter the balance between investment in growth and thermogenic function. To test this, one group of chicks was exposed to 7 degreesC and one group to 24 degreesC during foraging throughout

  8. 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

  9. 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

  10. Effects of using biofertilizer on forage maize growth and soil microbial number%施用生物菌肥对饲用玉米生长和土壤微生物数量的影响

    Institute of Scientific and Technical Information of China (English)

    段淇斌; 赵冬青; 姚拓; 韩华雯; 刘婷

    2015-01-01

    对饲用玉米进行随机区组试验,测定了生物菌肥对玉米生长指标(株高、干鲜比和地上生物量)、土壤有效养分(有效氮、有效磷和有效钾)以及土壤微生物(细菌、真菌和放线菌)的影响。结果表明,施用生物菌肥对玉米生长有着促进作用,玉米株高和地上植物量较对照分别提高6.3%和10.1%,且与对照差异显著(P <0.05);土壤有效氮、有效磷和有效钾显著增加(P <0.05),分别较对照增加7.7%,27.9%和7.5%,其中,有效磷增加明显;土壤细菌和放线菌数量显著增加(P <0.05),分别较对照增加322.0%和101.6%,而真菌的数量显著低于对照(P <0.05),与对照相比,施用生物菌肥后,土壤真菌数量减少了67.9%。%By randomized block design of experiment tested on the forage maize,the paper determined the biofertilizer's effects on the growth index (plant height,dry-fresh ratio and aboveground biomass),available soil nutrention (available nitrogen,available phosphorus and available potassium)and soil microorganism(bacteria, fungi and actinomycetes).The results showed that using the biofertilizer have promoted forage maize's growth, which increased the plant height (6.3%)and aboveground biomass (10.1%)compared with the contorl (P <0.05).There were a significant difference (P <0.05)on the available nitrogen,available phosphorus and availa-ble potassium in the soil,which increased,7.7%,27.9% and 7.5% respectively compared with the control.A-mong them,the increase of available phosphorus was obvious.The edaphic bacteria and actinomycetes observ-ably increased compared to the control (P <0.05),which respectively improved 322.0% and 101.6%.But,the quantity of fungi was lower than that of the contrast (P <0.05),which reduced about 67.9% after using the biofertilizer.

  11. The Inhibitory Effects of Cu^2+ Stress on Seed Germination, Seedling Growth and Root Elongation for Forage Grasses%Cu^2+胁迫对牧草种子发芽、幼苗生长及根伸长的影响

    Institute of Scientific and Technical Information of China (English)

    俞哲辉; 李海飞; 朱维琴

    2011-01-01

    This inhibitory effects of Cu^2+ stress on seed germination, seedling growth and root elongation for different forage grasses were investigated by hydroponics in designed experimental study. The study suggests that seed germination and seedling growth of Coronilla varia and Astragalus adsurgens Pall all tend to decline with the growing level of Cu^2+. The growth of the forage grass seed and the seeding root were prohibited with the rising level of the Cu^2+ , while the effects for complete growth inhabitation differs widely with Cu^2+ level. With the increasing concentration for Cu^2+ , the probability for growth inhibition of the forage grass seed roots are likely to go up as well. On average, the inbitory effects from Cu^2+ stress for Sorghum bicolor and rye of Dongmu No. 70 were lesser than those for Coronilla varia and Astragalus adsurgens Pall.%选择水培法进行了Cu^2+胁迫对牧草种子发芽、幼苗生长及根伸长的影响试验。结果表明,小冠花和沙打旺种子的发芽率和发芽势随Cu^2+浓度的升高呈抑制趋势;各牧草种子的根长和苗长随Cu^2+浓度的增加而降低,但各牧草种子根系被完全抑制的浓度则各不相同,随着Cu^2+浓度的增大各牧草种子的根系抑制率增大。总体看,高丹草和冬牧70黑麦对Cu^2+胁迫的耐受程度大于小冠花和沙打旺。

  12. Factors affecting forage stand establishment

    Directory of Open Access Journals (Sweden)

    Sulc R.M.

    1998-01-01

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

  13. Study on the Average Temperature of Forage Growth Period Interpolation Method%天然牧草生育期平均气温插值方法研究

    Institute of Scientific and Technical Information of China (English)

    于士凯; 姚艳敏; 王德营; 唐鹏钦; 陈仲新; 王道龙

    2012-01-01

    天然牧草生育期平均气温是牧草生长、生态环境保护等模型的重要参数.为了找出适宜天然牧草生育期平均气温的差值方法,以内蒙古自治区为研究区域,根据气温的垂直变化规律,将不同经纬度和海拔高度上的气象站点牧草生育期平均气温数据根据海拔高程投影到虚拟0海平面上,利用反距离插值(IDW)、样条函数(Spline)插值、克里金(Kriging)插值3种插值方法进行研究区域牧草生育期平均气温的空间分布推算,再运用DEM数据进行校正,比较分析最适宜的牧草生育期平均气温空间插值方法.3种插值方法平均误差为:IDW插值(-1.34%)>Spline插值(1.11%)>Kriging插值(0.36%);RMSE值:Kriging插值<IDW插值<Spline插值,其值分别为0.36<0.69<0.74.MAE值:Kriging插值<Spline插值<IDW插值,其值分别为0.14<0.33<0.35.研究结果表明,克里金(Kriging)插值为牧草生育期平均气温最优插值方法.%The average temperature of forage growth period was an important parameter for the model of grass crop growth and eco-environmental protection. In order to find out the optimum method for the average temperature interpolation of grass growth period, this paper took the Inner Mongolia Autonomous Region as the study areas. Firstly, according to the temperature vertical changing regularities, the average temperature data in pasture growth period of all climate sites were projected in different longitude and latitude to the virtual 0 sea level based on the latitude. Spline, IDW, Kriging interpolation methods were used to carry on the data interpolation. And then DEM data was used to conduct the temperature correction. The average errors of three interpolation methods were: IDW interpolation (-1.34%) > Spline Interpolation (1.11%) > the Kriging Interpolation (0.36%). The RMSE value: Kriging interpolation < IDW interpolation < Spline interpolation and the values were 0.36 < 0.69 < 0.74. The MAE value

  14. 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.

  15. Genotypic Differences of Forage Crop Tolerance to Acid Soils

    Institute of Scientific and Technical Information of China (English)

    YANGYUAI; CHUXIANGYUN; 等

    1998-01-01

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

  16. Balancing selection shapes density-dependent foraging behaviour.

    Science.gov (United States)

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

    2016-11-10

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

  17. Fatty acid profile of meat, diurnal changes in volatile fatty acids, rumen fluid parameters, and growth performance in Korean native (Hanwoo steers fed high- and low-forage diets supplemented with chromium-methionine

    Directory of Open Access Journals (Sweden)

    Bae-Hun Lee

    Full Text Available ABSTRACT The objective of this study was to determine the effects of forage level in diets supplemented with chromium-methionine (Cr-Met on rumen fluid parameters, meat fatty acid composition, and performance of Korean beef (Hanwoo steers. Twenty-three Hanwoo steers were used in this experiment. A completely randomized design and repeated measurements were used to analyze the data set. Beef steers were fed diets containing high (10 head; average body weight (BW = 525.1±27.5; forage:concentrate (F:C = 60:40 (60F and low (13 head; average BW = 531.8±32.4; F:C = 40:60 ratio (40F forage diets supplemented with Cr-Met for 60 d. Dry matter intake, BW, and feed efficiency were not different between the two treatment groups. Fatty acid composition of meat including myristate, stearate, and gamma linoleate was not different between the two groups; however, palmitate, palimtoleate, and linoleate were higher in 60F group than 40F group. Ammonia-N showed a higher trend in 40F group, whereas pH demonstrated higher values in 60F group. Ruminal acetate was higher in 60F group than 40F group and maintained a high trend throughout the sampling time, whereas no differences were found in ruminal propionate, butyrate, and valerate between two groups. A high-forage diet (60% improves meat quality and has no adverse effects on performance of Hanwoo steers.

  18. Geographic structure of adelie penguin populations: overlap in colony-specific foraging areas

    Science.gov (United States)

    Ainley, D.G.; Ribic, C.A.; Ballard, G.; Heath, S.; Gaffney, I.; Karl, B.J.; Barton, K.J.; Wilson, P.R.; Webb, S.

    2004-01-01

    In an investigation of the factors leading to geographic structuring among Ade??lie Penguin (Pygoscelis adeliae) populations, we studied the size and overlap of colony-specific foraging areas within an isolated cluster of colonies. The study area, in the southwestern Ross Sea, included one large and three smaller colonies, ranging in size from 3900 to 135000 nesting pairs, clustered on Ross and Beaufort Islands. We used triangulation of radio signals from transmitters attached to breeding penguins to determine foraging locations and to define colony-specific foraging areas during the chick-provisioning period of four breeding seasons, 1997-2000. Colony populations (nesting pairs) were determined using aerial photography just after egg-laying; reproductive success was estimated by comparing ground counts of chicks fledged to the number of breeding pairs apparent in aerial photos. Foraging-trip duration, meal size, and adult body mass were estimated using RFID (radio frequency identification) tags and an automated reader and weighbridge. Chick growth was assessed by weekly weighing. We related the following variables to colony size: foraging distance, area, and duration; reproductive success; chick meal size and growth rate; and seasonal variation in adult body mass. We found that penguins foraged closest to their respective colonies, particularly at the smaller colonies. However, as the season progressed, foraging distance, duration, and area increased noticeably, especially at the largest colony. The foraging areas of the smaller colonies overlapped broadly, but very little foraging area overlap existed between the large colony and the smaller colonies, even though the foraging area of the large colony was well within range of the smaller colonies. Instead, the foraging areas of the smaller colonies shifted as that of the large colony grew. Colony size was not related to chick meal size, chick growth, or parental body mass. This differed from the year previous to

  19. Effects of Plant Density on Forage Nutritive Value of Whole Plant Corn

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-wang; HU Chang-hao; WANG Kong-jun; DONG Shu-ting; LIU Peng

    2004-01-01

    In the field experiment, the effects of plant densities (75000, 112 500 and 150 000 plants ha-1) on forage nutritive value of whole plant corn (WPC) were studied from 1999 to 2001.The results demonstrated that with the increasing of plant density, the forage matter yield per plant corn decreased significantly, while the fresh matter and dry matter per hectare corn increased significantly, and a higher grains yield was gotten at higher plant densities. Forage nutritive quality of whole plant corn was changed as plant density increased, the crude protein (CP), ether extract (EE), crude fiber (CF),nitrogen free extract (NFE) and general energy (GE) yields increased obviously. Increasing plant density reasonably with the application of plant growth regulators could improve plant properties, harvest more forage matter, and enhance forage nutritive value of WPC.

  20. When Michaelis and Menten met Holling: towards a mechanistic theory of plant nutrient foraging behaviour.

    Science.gov (United States)

    McNickle, Gordon G; Brown, Joel S

    2014-10-22

    Plants are adept at assessing and responding to nutrients in soil, and generally proliferate roots into nutrient-rich patches. An analogy between this growth response and animal foraging movement is often drawn, but because of differences between plants and animals it has not always been clear how to directly apply existing foraging theory to plants. Here we suggest one way to unite pre-existing ideas in plant nutrient uptake with foraging theory. First, we show that the Michaelis-Menten equation used by botanists and the Holling disc equation used by zoologists are actually just rearrangements of the same functional response. This mathematical unity permits the translation of existing knowledge about the nutrient uptake physiology of plants into the language of foraging behaviour, and as a result gives botanists direct access to foraging theory. Second, we developed a model of root foraging precision based on the Holling disc equation and the marginal value theorem, and parameterize it from the literature. The model predicts (i) generally plants should invest in higher quality patches compared to lower quality patches, and as patch background-contrast increases; (ii) low encounter rates between roots and nutrients result in high root foraging precision; and (iii) low handling times for nutrients should result in high root foraging precision. The available data qualitatively support these predictions. Third, to parameterize the model above we undertook a review of the literature. From that review we obtained parameter estimates for nitrate and/or ammonium uptake for 45 plant species from 38 studies. We observe that the parameters ranged over six orders of magnitude, there was no trade-off in foraging ability for nitrate versus ammonium: plants that were efficient foragers for one form of nitrogen were efficient foragers for the other, and there was also no phylogenetic signal in the parameter estimates. Published by Oxford University Press on behalf of the Annals

  1. 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

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

    NARCIS (Netherlands)

    Hofstede, Frouke Elisabeth

    2006-01-01

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

  3. Variations in plant forage quality in the range of the Porcupine caribou herd

    Directory of Open Access Journals (Sweden)

    Jill Johnstone

    2002-06-01

    Full Text Available Understanding potential impacts of vegetation change on caribou energetics requires information on variations in forage quality among different plant types and over time. We synthesized data on forage quality (nitrogen, neutral detergent fiber and dry matter digestibility for 10 plant growth forms from existing scientific literature and from field research in the Arctic National Wildlife Refuge, Alaska. These data describe forage quality of plant species in habitats found within the summer and winter range of the Porcupine caribou herd in northwestern Canada and northern Alaska, U.S.A. We compared mean levels of summer forage quality among growth forms and, where possible, estimated seasonal changes in forage quality. Preferred forage groups (deciduous shrubs, forbs, and cottongrass flowers had higher nitrogen and digestibility, and lower fiber content, than other growth forms. Nitrogen concentration in green biomass peaked at the onset of the growing season in forbs and deciduous shrubs, whereas graminoids reached peak nitrogen concentrations approximately 15-30 days after growth initiation. In vitro dry matter digestibility (IVDMD and concentration of neutral detergent fiber (NDF of green biomass differed among growth forms, but did not show strong seasonal changes. IVDMD and NDF concentrations were correlated with nitrogen concentrations in studies that had paired sampling.

  4. 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. ...

  5. 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.

  6. Phylogenetic meta-analysis of the functional traits of clonal plants foraging in changing environments.

    Science.gov (United States)

    Xie, Xiu-Fang; Song, Yao-Bin; Zhang, Ya-Lin; Pan, Xu; Dong, Ming

    2014-01-01

    Foraging behavior, one of the adaptive strategies of clonal plants, has stimulated a tremendous amount of research. However, it is a matter of debate whether there is any general pattern in the foraging traits (functional traits related to foraging behavior) of clonal plants in response to diverse environments. We collected data from 97 published papers concerning the relationships between foraging traits (e.g., spacer length, specific spacer length, branch intensity and branch angle) of clonal plants and essential resources (e.g., light, nutrients and water) for plant growth and reproduction. We incorporated the phylogenetic information of 85 plant species to examine the universality of foraging hypotheses using phylogenetic meta-analysis. The trends toward forming longer spacers and fewer branches in shaded environments were detected in clonal plants, but no evidence for a relation between foraging traits and nutrient availability was detected, except that there was a positive correlation between branch intensity and nutrient availability in stoloniferous plants. The response of the foraging traits of clonal plants to water availability was also not obvious. Additionally, our results indicated that the foraging traits of stoloniferous plants were more sensitive to resource availability than those of rhizomatous plants. In consideration of plant phylogeny, these results implied that the foraging traits of clonal plants (notably stoloniferous plants) only responded to light intensity in a general pattern but did not respond to nutrient or water availability. In conclusion, our findings on the effects of the environment on the foraging traits of clonal plants avoided the confounding effects of phylogeny because we incorporated phylogeny into the meta-analysis.

  7. Autumn Maize Intercropped with Tropical Forages: Crop Residues, Nutrient Cycling, Subsequent Soybean and Soil Quality

    Directory of Open Access Journals (Sweden)

    Francisco Cézar Belchor Lages Pereira

    2016-01-01

    Full Text Available ABSTRACT Autumn maize intercropped with tropical forages can raise the amount of crop residues and improve nutrient cycling, favoring subsequent soybean crop. The objective of this study was to evaluate the effect of forms of implementation of intercropping of irrigated autumn maize with tropical forages on yield, decomposition, nutrient accumulation and release, and on the ratio of lignin/total N of forage residues, yield components, and grain yield of subsequent soybean, and on soil physical and chemical properties, under no-tillage in lowland Cerrado. The experiment was arranged in randomized blocks in a factorial (4 × 3 + 1 design with one control and four replications. The treatments consisted of four forages: Palisade grass, Congo grass, and two Guinea grass cultivars (Tanzânia and Áries; and three methods of sowing intercrops of forage-autumn maize: forage sown simultaneously with maize in the sowing furrow, mixed with fertilizer; forage sown by broadcasting on the day of maize sowing; and forage seeds mixed with fertilizer broadcast on maize in growth stage V4; plus a control (maize monoculture. The decomposition and nutrient release rate of the forage residues were evaluated by the litter bag method, 30, 60, 90, and 120 days after desiccation. Sowing the forages in the furrow and by broadcasting raise the total amount of maize residues compared to method V4. Regardless of the forage type and sowing methods, intercropping increases the amount of residues compared to maize monoculture. The forages and sowing methods had no influence on nutrient accumulation in the residues at the time of desiccation and at the lowest lignin/total N ratio in Congo grass residues, and a logarithmic decay was observed. Forage and sowing methods did not influence the macronutrient release rate from crop residues for 120 days after desiccation; the release of N, P, K and Mg is logarithmic and the release of Ca and S exponential. Forage and sowing methods do

  8. 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.

  9. Invasive clonal plant species have a greater root-foraging plasticity than non-invasive ones.

    Science.gov (United States)

    Keser, Lidewij H; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2014-03-01

    Clonality is frequently positively correlated with plant invasiveness, but which aspects of clonality make some clonal species more invasive than others is not known. Due to their spreading growth form, clonal plants are likely to experience spatial heterogeneity in nutrient availability. Plasticity in allocation of biomass to clonal growth organs and roots may allow these plants to forage for high-nutrient patches. We investigated whether this foraging response is stronger in species that have become invasive than in species that have not. We used six confamilial pairs of native European clonal plant species differing in invasion success in the USA. We grew all species in large pots under homogeneous or heterogeneous nutrient conditions in a greenhouse, and compared their nutrient-foraging response and performance. Neither invasive nor non-invasive species showed significant foraging responses to heterogeneity in clonal growth organ biomass or in aboveground biomass of clonal offspring. Invasive species had, however, a greater positive foraging response in terms of root and belowground biomass than non-invasive species. Invasive species also produced more total biomass. Our results suggest that the ability for strong root foraging is among the characteristics promoting invasiveness in clonal plants.

  10. Availability and toxicity of cadmium to forage grasses grown in contaminated soil.

    Science.gov (United States)

    Silva, Enilson B; Fonseca, Felipe G; Alleoni, Luís R F; Nascimento, Sandra S; Grazziotti, Paulo H; Nardis, Bárbara O

    2016-09-01

    It is important to know the mechanisms for forage development, especially those related to the tolerance of potentially toxic elements, when considering their use in phytoremediation in heavy metal contaminated areas. In this study, we evaluated plant growth, concentration, and the availability of cadmium (Cd) for forage grasses (Panicum maximum Jacq. cv. Aruana and cv. Tanzânia; Brachiaria decumbens cv. Basilisk; Brachiaria brizantha cv. Xaraés and cv. Marandu) cultivated in Cd contaminated soils. The experiments were performed under greenhouse conditions over a 90-day evaluation period, and the Cd rates were 2, 4, and 12 mg/kg of soil. The relative growth rate of the forage grasses decreased as Cd rates increased, and the following descending order of susceptibility was observed: Marandu > Xaraés > Aruana > Tanzânia > Basilisk, with regard to phytotoxicity in these plants. The forage Cd concentration increased in line with increases in the Cd rates. Cd contents extracted by Mehlich-1 and by diethylenetriaminepentaacetic acid presented high positive correlation with forage relative growth. The forage plants did not block Cd entry into the food chain because they were not capable of limiting Cd absorption.

  11. 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.

  12. Foraging currencies, metabolism and behavioural routines.

    Science.gov (United States)

    Houston, Alasdair I; McNamara, John M

    2014-01-01

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

  13. 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.

  14. Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary.

    Science.gov (United States)

    Rossman, Sam; Ostrom, Peggy H; Stolen, Megan; Barros, Nélio B; Gandhi, Hasand; Stricker, Craig A; Wells, Randall S

    2015-06-01

    We examine individual specialization in foraging habits (foraging habitat and trophic level) of female bottlenose dolphins (Tursiops truncatus) resident in Sarasota Bay, Florida, USA, by analyzing time series of stable isotope (δ(15)N and δ(13)C) values in sequential growth layer groups within teeth. The isotope data provide a chronology of foraging habits over the lifetime of the individual and allowed us to show that female bottlenose dolphins exhibit a high degree of individual specialization in both foraging habitat and trophic level. The foraging habits used by adult females are similar to those they used as calves and may be passed down from mother to calf through social learning. We also characterized the foraging habits and home range of each individual by constructing standard ellipses from isotope values and dolphin sightings data (latitude and longitude), respectively. These data show that Sarasota Bay bottlenose dolphins forage within a subset of the habitats in which they are observed. Moreover, females with similar observational standard ellipses often possessed different foraging specializations. Female bottlenose dolphins may demonstrate individual specialization in foraging habits because it reduces some of the cost of living in groups, such as competition for prey.

  15. Developing Cyber Foraging Applications for Portable Devices

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø; Bouvin, Niels Olof

    2008-01-01

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

  16. Visual Foraging With Fingers and Eye Gaze.

    Science.gov (United States)

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

    2016-03-01

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

  17. 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,...

  18. 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,...

  19. Improving the scale and precision of hypotheses to explain root foraging ability.

    Science.gov (United States)

    Kembel, Steven W; De Kroon, Hans; Cahill, James F; Mommer, Liesje

    2008-06-01

    Numerous hypotheses have been proposed to explain the wide variation in the ability of plants to forage for resources by proliferating roots in soil nutrient patches. Comparative analyses have found little evidence to support many of these hypotheses, raising the question of what role resource-foraging ability plays in determining plant fitness and community structure. In the present viewpoint, we respond to Grime's (2007; Annals of Botany 99: 1017-1021) suggestion that we misinterpreted the scope of the scale-precision trade-off hypothesis, which states that there is a trade-off between the spatial scale over which plant species forage and the precision with which they are able to proliferate roots in resource patches. We use a meta-analysis of published foraging scale-precision correlations to demonstrate that there is no empirical support for the scale-precision trade-off hypothesis. Based on correlations between foraging precision and various plant morphological and ecophysiological traits, we found that foraging precision forms part of the 'fast' suite of plant traits related to rapid growth rates and resource uptake rates. We suggest there is a need not only to examine correlations between foraging precision and other plant traits, but to expand our notion of what traits might be important in determining the resource-foraging ability of plants. By placing foraging ability in the broader context of plant traits and resource economy strategies, it will be possible to develop a new and empirically supported framework to understand how plasticity in resource uptake and allocation affect plant fitness and community structure.

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

    NARCIS (Netherlands)

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

    2001-01-01

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

  1. Foraging behaviour by parasitoids in multiherbivore communities

    NARCIS (Netherlands)

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

    2013-01-01

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

  2. Increased carrying capacity with perennial forage kochia

    Science.gov (United States)

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

  3. Optimal forager against ideal free distributed prey.

    Science.gov (United States)

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

    2015-07-01

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

  4. Universality classes of foraging with resource renewal

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

    Carthey, Alexandra J R; Banks, Peter B

    2015-07-01

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

  6. Effects of liming on forage availability and nutrient content in a forest impacted by acid rain.

    Directory of Open Access Journals (Sweden)

    Sarah E Pabian

    Full Text Available Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus and other forest herbivores. Liming is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before liming and up to 5 years post-liming on 2 treated and 2 untreated 100-ha sites. Before liming, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of liming on forb biomass, with a 2.7 fold increase on limed sites, but no biomass response in other vegetation groups. We observed positive effects of liming on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to liming by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer.

  7. The FGLamide-allatostatins influence foraging behavior in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Christine Wang

    Full Text Available Allatostatins (ASTs are multifunctional neuropeptides that generally act in an inhibitory fashion. ASTs were identified as inhibitors of juvenile hormone biosynthesis. Juvenile hormone regulates insect metamorphosis, reproduction, food intake, growth, and development. Drosophila melanogaster RNAi lines of PheGlyLeu-amide-ASTs (FGLa/ASTs and their cognate receptor, Dar-1, were used to characterize roles these neuropeptides and their respective receptor may play in behavior and physiology. Dar-1 and FGLa/AST RNAi lines showed a significant reduction in larval foraging in the presence of food. The larval foraging defect is not observed in the absence of food. These RNAi lines have decreased for transcript levels which encodes cGMP- dependent protein kinase. A reduction in the for transcript is known to be associated with a naturally occurring allelic variation that creates a sitter phenotype in contrast to the rover phenotype which is caused by a for allele associated with increased for activity. The sitting phenotype of FGLa/AST and Dar-1 RNAi lines is similar to the phenotype of a deletion mutant of an AST/galanin-like receptor (NPR-9 in Caenorhabditis elegans. Associated with the foraging defect in C. elegans npr-9 mutants is accumulation of intestinal lipid. Lipid accumulation was not a phenotype associated with the FGLa/AST and Dar-1 RNAi lines.

  8. 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.

  9. Determination of Tropical Forage Preferences Using Two Offering Methods in Rabbits

    Directory of Open Access Journals (Sweden)

    A. M. Safwat

    2014-04-01

    Full Text Available Two methods of feed preference trials were compared to evaluate the acceptability of 5 fresh foliages: Leucaena leucocephala, Moringa oleifera, Portulaca oleracea, Guazuma ulmifolia, and Brosimum alicastrum that was included as control. The evaluation included chemical analyses and forage intake by rabbits. The first method was a cafeteria trial; 12 California growing rabbits aged 8 wk, allocated in individual cages, were offered the five forage plants at the same time inside the cage, while in the second trial 60 California growing rabbits aged 8 wk, allocated individually, were randomly distributed into 5 experimental groups (n = 12/group; for each group just one forage species was offered at a time. The testing period for each method lasted for 7 d, preceded by one week of adaptation. The results showed that B. alicastrum and L. lecocephala were the most preferred forages while on the contrary G. ulmifolia was the least preferred one by rabbits. The results also revealed that the CV% value for the 2nd method (16.32%, which the tested forages were presented separately to rabbits, was lower and methodologically more acceptable than such value for the 1st method (34.28%, which all forages were presented together at the same time. It can be concluded that a range of tropical forages were consumed in acceptable quantities by rabbits, suggesting that diets based on such forages with a concentrate supplement could be used successfully for rabbit production. However, growth performance studies are still needed before recommendations could be made on appropriate ration formulations for commercial use.

  10. Determination of tropical forage preferences using two offering methods in rabbits.

    Science.gov (United States)

    Safwat, A M; Sarmiento-Franco, L; Santos-Ricalde, R H; Nieves, D

    2014-04-01

    Two methods of feed preference trials were compared to evaluate the acceptability of 5 fresh foliages: Leucaena leucocephala, Moringa oleifera, Portulaca oleracea, Guazuma ulmifolia, and Brosimum alicastrum that was included as control. The evaluation included chemical analyses and forage intake by rabbits. The first method was a cafeteria trial; 12 California growing rabbits aged 8 wk, allocated in individual cages, were offered the five forage plants at the same time inside the cage, while in the second trial 60 California growing rabbits aged 8 wk, allocated individually, were randomly distributed into 5 experimental groups (n = 12/group); for each group just one forage species was offered at a time. The testing period for each method lasted for 7 d, preceded by one week of adaptation. The results showed that B. alicastrum and L. lecocephala were the most preferred forages while on the contrary G. ulmifolia was the least preferred one by rabbits. The results also revealed that the CV% value for the 2nd method (16.32%), which the tested forages were presented separately to rabbits, was lower and methodologically more acceptable than such value for the 1(st) method (34.28%), which all forages were presented together at the same time. It can be concluded that a range of tropical forages were consumed in acceptable quantities by rabbits, suggesting that diets based on such forages with a concentrate supplement could be used successfully for rabbit production. However, growth performance studies are still needed before recommendations could be made on appropriate ration formulations for commercial use.

  11. Sowing date for forage maize hybrids harvested at different growth stages = Época de semeadura de híbridos de milho forrageiro colhidos em diferentes estádios de maturação

    Directory of Open Access Journals (Sweden)

    Marcelo Cruz Mendes

    2015-06-01

    Full Text Available The sowing dates and harvesting times of forage maize are important factors in high-yield forage production. The objective of this study was to evaluate the participation of plant components for different sowing dates and harvest stages, in commercial maize hybrids recommended for the production of forage. The experimental design was of randomised blocks, three replications, in a 4 x 2 factorial scheme, being four maize hybrids (P30B39H, DKB245, 2B688H and DKB330Y and two sowing dates (October and November. The experiment was carried out in Guarapuava, in the state of Paraná, Brazil (PR. Evaluations were done at stages R4 and R5, when the percentage of dry matter was evaluated by means of fractionation for the leaves (PPFOL, stem (PPCOL, grain (PPGR, and bracts and cob (PPSAB. The hybrid DKB245 displayed less participation of the leaves, stem, bracts and cob, and a higher participation of grain at the farinaceous and hard farinaceous grain reproductive stages, irrespective of sowing time. With the advancement of the farinaceous grain reproductive stage to hard farinaceous grain, there was an increase in the percentage of grain in the hybrids under evaluation and a reduction in the participation of the leaves, stem, bracts and cob for the two sowing dates (October and November. At the hard farinaceous grain stage, the genotypes under evaluation were less influenced by the effect of sowing time, there being a greater participation of the grain for all genotypes; with the hard farinaceous grain stage being indicated for harvesting the forage. = Época de semeadura e ponto de corte de plantas de milho forrageiro são fatores importantes na produção de forragem de alto rendimento. O objetivo deste trabalho foi avaliar a participação dos componentes da planta em diferentes épocas de semeadura e estádios de colheita, em híbridos comerciais de milho recomendados para produção de forragem. O delineamento foi em blocos casualizados, com tr

  12. Sexual segregation in foraging giraffe

    Science.gov (United States)

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

    2017-02-01

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

  13. 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

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

    Science.gov (United States)

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

    2013-07-01

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

  15. 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…

  16. A review on studies in forage in China

    Institute of Scientific and Technical Information of China (English)

    LONG Wenxing; YANG Xiaobo; QI Meiying

    2007-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Andrew D. Higginson

    2011-01-01

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

  18. Worker honey bee pheromone regulation of foraging ontogeny

    Science.gov (United States)

    Pankiw, Tanya

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

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

    OpenAIRE

    Michael eRivera; Matina eDonaldson-Matasci; Anna eDornhaus

    2015-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Evlyn Pless

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

  3. Fishing amplifies forage fish population collapses.

    Science.gov (United States)

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

    2015-05-26

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

  4. Foraging behavior of larval cod ( Gadus morhua ) influenced by prey density and hunger

    DEFF Research Database (Denmark)

    Munk, Peter

    1995-01-01

    Fish larvae meet diverse environmental conditions at sea, and larval growth and chance of survival depend on a flexible response to environmental variability. The present study focuses on the flexibility of the foraging behaviour of larval cod in a series of laboratory experiments on larval search...

  5. Enhancing forage yields and soil conservation by interseeding alfalfa into silage corn

    Science.gov (United States)

    Recent field studies have identified prohexadione-calcium (PHD) as an effective plant growth regulator for enhancing the establishment of alfalfa interseeded into corn as a dual-purpose cover and forage crop. Foliar applications of PHD on seedlings doubled or tripled stand survival of interseeded al...

  6. Ambient Air Temperature Does Not Predict whether Small or Large Workers Forage in Bumble Bees (Bombus impatiens

    Directory of Open Access Journals (Sweden)

    Margaret J. Couvillon

    2010-01-01

    Full Text Available Bumble bees are important pollinators of crops and other plants. However, many aspects of their basic biology remain relatively unexplored. For example, one important and unusual natural history feature in bumble bees is the massive size variation seen between workers of the same nest. This size polymorphism may be an adaptation for division of labor, colony economics, or be nonadaptive. It was also suggested that perhaps this variation allows for niche specialization in workers foraging at different temperatures: larger bees might be better suited to forage at cooler temperatures and smaller bees might be better suited to forage at warmer temperatures. This we tested here using a large, enclosed growth chamber, where we were able to regulate the ambient temperature. We found no significant effect of ambient or nest temperature on the average size of bees flying to and foraging from a suspended feeder. Instead, bees of all sizes successfully flew and foraged between 16∘C and 36∘C. Thus, large bees foraged even at very hot temperatures, which we thought might cause overheating. Size variation therefore could not be explained in terms of niche specialization for foragers at different temperatures.

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

    Directory of Open Access Journals (Sweden)

    Michael eRivera

    2015-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Thrine Moen Heggberget

    2002-06-01

    climate may cause an altitudinal upward shift in the production of mat-forming lichens in alpine, sub-arctic regions. This is due to an increased potential for lichen growth at high altitudes, combined with increased competition from taller-growing vascular plants at lower altitudes, where the biomass of Betula nana in particular will increase. Matforming lichens dominant on dry, windblown ridges are easily overgrazed at high reindeer densities. This has longterm effects due to lichens’ slow regeneration rate, but may also reduce competition from vascular plants in a long time perspective. Fires may act in a similar way in some forested areas. Accessibility of winter forage depends on plant biomass, snow depth and hardness; ice crusts or exceptionally deep snow may result in starvation and increased animal mortality. Calf recruitment appears to be low and/or highly variable where winter ranges are overgrazed and hard or deep snow is common. Population decline in several Rangifer tarandus spp. has been associated with snow-rich winters. Effects tend to be delayed and cumulative, particularly on calves. This is mainly ascribed to feeding conditions for young animals which later affect age at maturation. Global warming may increase the frequency of deep or hard snow on reindeer ranges in Norway, due to increased precipitation and more frequent mild periods in winter. We hypothesise that potential benefits from increased plant productivity due to global warming will be counteracted by shifts in the distribution of preferred lichen forage, reduction of the areas of suitable winter ranges, and generally reduced forage accessibility in winter.

  9. Forage and seed production of Puero (Pueraria javanica in a Different Light intensity level

    Directory of Open Access Journals (Sweden)

    Fanindi A

    2016-06-01

    Full Text Available Puero (Pueraria javanica is forage that can serve as a cover crop in plantations. The limiting factor for plant growth in the plantation is the light intensity, therefore the influence of light intensity on forage and seed production of Puero needs to be examined. Research was conducted at Kaum Pandak Research station of Indonesian Research Institute for Animal Production Bogor and Laboratory of Agrostology Faculty of Animal Husbandry, Bogor Agricultural University, for 16 months. Four levels of light intensity,i.e 100, 80,60 and 40% were applied, leguminosainous species Puero (Pueraria javanica, was used. The treatments were arangged in Randomized Complete Block Design with 3 replications. Data collected were analyzed by ANOVA and Duncan’s Multiple Range Test. Forage production was evaluated in one year. The forage quality and digestibility (invitro were assessed. Seed production was recorded accumulatively from seasonal seed production during one year. Results show that light intensity affected (P 0.05 quality and digestibility of Puero. The highest forage and seed production of Puero were obtained from full light intensity (100%. and seed production of Puero was affected (P < 0.05 by light intensity. The seed quality of Puero was also affected by light intensity. The best seed quality of Puero was achieved by from 80% light intensity.

  10. Feed intake and activity level of two broiler genotypes foraging different types of vegetation in the finishing period

    DEFF Research Database (Denmark)

    Almeida, Gustavo Fonseca; Hinrichsen, Lena Karina; Horsted, Klaus;

    2012-01-01

    were included in a 2 × 2 factorial design with groups of 25 birds replicated 3 times. The use of outdoor areas, performance, and forage intake were investigated. To identify possible differences in foraging activity, the use of the range was monitored one day per week at 4 different times of the day......A study was performed with 2 broiler genotypes (slow and medium growth) restricted in supplementary feed and foraging 2 different mixed vegetations (grass/clover or chicory) to identify possible benefits of herbage on nutrition during the finishing period (80 to 113 d of age). Three hundred birds....... Feed intake from foraging was estimated by killing 4 birds per plot (2 males and 2 females) in the morning and in the evening on 3 d during the experiment and measuring crop content. Vegetation type did not influence broiler use of the free-range area, feed intake, or performance. Differences...

  11. Evolution of foraging behavior in Drosophilid larvae

    Science.gov (United States)

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

    2015-03-01

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

  12. Spatiotemporal chemotactic model for ant foraging

    Science.gov (United States)

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

    2014-12-01

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

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

    Institute of Scientific and Technical Information of China (English)

    阎萍

    2005-01-01

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

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

    African Journals Online (AJOL)

    Hilaire

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

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

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Birgit Ehmer

    1995-01-01

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

  17. Insect-foraging in captive owl monkeys (Aotus nancymaae).

    Science.gov (United States)

    Wolovich, Christy K; Rivera, Jeanette; Evans, Sian

    2010-08-01

    Whereas the diets of diurnal primate species vary greatly, almost all nocturnal primate species consume insects. Insect-foraging has been described in nocturnal prosimians but has not been investigated in owl monkeys (Aotus spp.). We studied 35 captive owl monkeys (Aotus nancymaae) in order to describe their foraging behavior and to determine if there were any age or sex differences in their ability to capture insect prey. Because owl monkeys cooperate in parental care and in food-sharing, we expected social interactions involving insect prey. We found that owl monkeys most often snatched flying insects from the air and immobilized crawling insects against a substrate using their hands. Immatures and adult female owl monkeys attempted to capture prey significantly more often than did adult males; however, there was no difference in the proportion of attempts that resulted in capture. Social interactions involving prey appeared similar to those with provisioned food, but possessors of prey resisted begging attempts more so than did possessors of other food. Owl monkeys attempted to capture prey often (mean = 9.5 +/- 5.8 attempts/h), and we speculate that the protein and lipid content of captured prey is important for meeting the metabolic demands for growth and reproduction.

  18. Relationship between channel morphology and foraging habitat for stream salmonids: Effects of body size

    Science.gov (United States)

    Cienciala, P.; Hassan, M. A.

    2014-12-01

    Channel morphology and dynamics strongly influence fish populations in running waters by defining habitat template for movement, spawning, incubation, and foraging. In this research we adopted a modeling approach to investigate how body size controls the relationship between salmonid fish and their foraging habitat in streams. Body size is a fundamental ecological parameter which affects resource acquisition, locomotory costs, metabolic rates, and competitive abilities. We focus on two specific questions. First, we examined how distinct types of channel morphology and associated flow fields shape specific growth potential for different body size classes of trout. Second, we modeled these fish-habitat relationships in a size-structured population in the presence of intraspecific competition. In the latter scenario, fish may not be able to occupy energetically optimal foraging habitat and the predicted specific growth potential may differ from the intrinsic habitat quality. To address the research questions, we linked a 2D hydrodynamic model with a bioenergetic foraging model for drift-feeding trout. Net energy intake, simulated for four study reaches with different channel morphology, was converted into maps of specific growth rate potential. We extended this model by including a component that enabled us to estimate territory size for fish of a given body size and account for the effects of competition on spatial distribution of fish. The predictions that emerge from our simulations highlight that fish body size is an important factor that determines the relationship between channel morphology and the quality of foraging habitat. The results also indicate that distinct types of channel morphology may give rise to different energetic conditions for different body size classes of drift-feeding salmonids.

  19. Nitrogen transfer between herbivores and their forage species

    NARCIS (Netherlands)

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

    2010-01-01

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

  20. 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...

  1. 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...

  2. Cell Wall Diversity in Forage Maize

    NARCIS (Netherlands)

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

    2015-01-01

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

  3. Investigating Optimal Foraging Theory in the Laboratory

    Science.gov (United States)

    Harden, Siegfried; Grilliot, Matthew E.

    2014-01-01

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

  4. The Dynamics of Infant Visual Foraging

    Science.gov (United States)

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

    2004-01-01

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

  5. Balancing organization and flexibility in foraging dynamics.

    Science.gov (United States)

    Tabone, Michaelangelo; Ermentrout, Bard; Doiron, Brent

    2010-10-07

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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

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

    2015-01-01

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

  8. Breeding success of a marine central place forager in the context of climate change: A modeling approach.

    Science.gov (United States)

    Massardier-Galatà, Lauriane; Morinay, Jennifer; Bailleul, Frédéric; Wajnberg, Eric; Guinet, Christophe; Coquillard, Patrick

    2017-01-01

    In response to climate warming, a southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in Subantarctic areas. Central place foragers, such as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. Understanding how central place foragers should modify their foraging behavior in response to changes in prey accessibility appears crucial. A spatially explicit individual-based simulation model (Marine Central Place Forager Simulator (MarCPFS)), including bio-energetic components, was built to evaluate effects of possible changes in prey resources accessibility on individual performances and breeding success. The study was calibrated on a particular example: the Antarctic fur seal (Arctocephalus gazella), which alternates between oceanic areas in which females feed and the land-based colony in which they suckle their young over a 120 days rearing period. Our model shows the importance of the distance covered to feed and prey aggregation which appeared to be key factors to which animals are highly sensitive. Memorization and learning abilities also appear to be essential breeding success traits. Females were found to be most successful for intermediate levels of prey aggregation and short distance to the resource, resulting in optimal female body length. Increased distance to resources due to climate warming should hinder pups' growth and survival while female body length should increase.

  9. Animal production and canopy attributes of Cynodon pasture managed under continuous stocking with wethers at three levels of forage allowance

    Directory of Open Access Journals (Sweden)

    Márcia Vendrúsculo dos Santos

    2012-01-01

    Full Text Available The objective of the present experiment was to evaluate the effect of forage allowance (3, 6 or 9 kg of green leaves dry matter (DM/100 kg of body weight (BW on both animal performance and attributes of Cynodon dactylon var.dactylon canopy managed under continuous stocking by wethers. The study was carried out with 27 Polwarth wethers throughout five 28-day periods, in a completely randomized experiment, which included three paddocks per treatment and three tester animals per paddock. Forage mass varied from 2878 to 6580 kg of DM/ha and was directly related to forage allowance. Leaves proportion (mean of 23% and leaves growth rate (mean of 25 kg of DM/ha/day varied between experimental periods in a similar rate for all treatments. Stocking rate varied from 652 to 2428 kg of LW/ha/day and was higher for the lowest forage allowance treatment. Individual BW gain (mean of 9.7 g/day or gain per area (mean of 406 g/ha/day were only affected by experimental periods. Forage intake was neither affected by treatments nor by periods (mean of 1042 g of DM/day. Cynodon dactylon var. dactylon pasture may be managed under continuous stocking by grazing wethers at forage allowances varying from 3 to 9 kg of green leaves dry matter/100 kg of BW without effects on canopy attributes or animal production.

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

    Science.gov (United States)

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

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

    Institute of Scientific and Technical Information of China (English)

    Thomas T.HILLS; Stephen BUTTERFILL

    2015-01-01

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

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

    Science.gov (United States)

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

    2014-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Luan D. Lima

    2013-12-01

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

  14. Scavenger: Transparent Development of Efficient Cyber Foraging Applications

    DEFF Research Database (Denmark)

    Kristensen, Mads Darø

    2010-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  17. Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees.

    Science.gov (United States)

    Chen, Weile; Koide, Roger T; Adams, Thomas S; DeForest, Jared L; Cheng, Lei; Eissenstat, David M

    2016-08-01

    Photosynthesis by leaves and acquisition of water and minerals by roots are required for plant growth, which is a key component of many ecosystem functions. Although the role of leaf functional traits in photosynthesis is generally well understood, the relationship of root functional traits to nutrient uptake is not. In particular, predictions of nutrient acquisition strategies from specific root traits are often vague. Roots of nearly all plants cooperate with mycorrhizal fungi in nutrient acquisition. Most tree species form symbioses with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi. Nutrients are distributed heterogeneously in the soil, and nutrient-rich "hotspots" can be a key source for plants. Thus, predicting the foraging strategies that enable mycorrhizal root systems to exploit these hotspots can be critical to the understanding of plant nutrition and ecosystem carbon and nutrient cycling. Here, we show that in 13 sympatric temperate tree species, when nutrient availability is patchy, thinner root species alter their foraging to exploit patches, whereas thicker root species do not. Moreover, there appear to be two distinct pathways by which thinner root tree species enhance foraging in nutrient-rich patches: AM trees produce more roots, whereas EM trees produce more mycorrhizal fungal hyphae. Our results indicate that strategies of nutrient foraging are complementary among tree species with contrasting mycorrhiza types and root morphologies, and that predictable relationships between below-ground traits and nutrient acquisition emerge only when both roots and mycorrhizal fungi are considered together.

  18. Does it pay to integrate irrigated forages in a beef cattle breeding operation in north Queensland?

    OpenAIRE

    2014-01-01

    The northern Australian beef industry accounts for approximately half of the national beef herd. It is currently challenged by a range of factors including decline in beef prices, limited live export trade, large farm debt levels, and low return on assets managed. Access to irrigation has been identified as one factor with potential to contribute to growth of the northern Australian beef industry. The development of irrigation for growing pasture and forage crops could extend the ability to s...

  19. Uncovering the complexity of ant foraging trails.

    Science.gov (United States)

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

    2012-01-01

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

  20. Adaptive Levy walks in foraging fallow deer.

    Directory of Open Access Journals (Sweden)

    Stefano Focardi

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

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

    Science.gov (United States)

    Lanan, Michele

    2014-01-01

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

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

    Science.gov (United States)

    Lanan, Michele

    2014-01-01

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

  3. Effect of interactions between harvester ants on forager decisions

    Directory of Open Access Journals (Sweden)

    Jacob D Davidson

    2016-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Andrew J Hoskins

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  7. Salt preferences of honey bee water foragers.

    Science.gov (United States)

    Lau, Pierre W; Nieh, James C

    2016-03-01

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

  8. BIOACCUMULATION OF HEAVY METALS IN FORAGE GRASSES

    Directory of Open Access Journals (Sweden)

    Adam Łukowski

    2017-02-01

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

  9. Polydomy enhances foraging performance in ant colonies.

    Science.gov (United States)

    Stroeymeyt, N; Joye, P; Keller, L

    2017-04-26

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

  10. Evaluating the use of plant hormones and biostimulators in forage pastures to enhance shoot dry biomass production by perennial ryegrass (Lolium perenne L.).

    Science.gov (United States)

    Zaman, Mohammad; Kurepin, Leonid V; Catto, Warwick; Pharis, Richard P

    2016-02-01

    Fertilisation of established perennial ryegrass forage pastures with nitrogen (N)-based fertilisers is currently the most common practice used on farms to increase pasture forage biomass yield. However, over-fertilisation can lead to undesired environmental impacts, including nitrate leaching into waterways and increased gaseous emissions of ammonia and nitrous oxide to the atmosphere. Additionally, there is growing interest from pastoral farmers to adopt methods for increasing pasture dry matter yield which use 'natural', environmentally safe plant growth stimulators, together with N-based fertilisers. Such plant growth stimulators include plant hormones and plant growth promotive microorganisms such as bacteria and fungi ('biostimulators', which may produce plant growth-inducing hormones), as well as extracts of seaweed (marine algae). This review presents examples and discusses current uses of plant hormones and biostimulators, applied alone or together with N-based fertilisers, to enhance shoot dry matter yield of forage pasture species, with an emphasis on perennial ryegrass.

  11. How past and present influence the foraging of clonal plants?

    Science.gov (United States)

    Louâpre, Philipe; Bittebière, Anne-Kristel; Clément, Bernard; Pierre, Jean-Sébastien; Mony, Cendrine

    2012-01-01

    Clonal plants spreading horizontally and forming a network structure of ramets exhibit complex growth patterns to maximize resource uptake from the environment. They respond to spatial heterogeneity by changing their internode length or branching frequency. Ramets definitively root in the soil but stay interconnected for a varying period of time thus allowing an exchange of spatial and temporal information. We quantified the foraging response of clonal plants depending on the local soil quality sampled by the rooting ramet (i.e. the present information) and the resource variability sampled by the older ramets (i.e. the past information). We demonstrated that two related species, Potentilla reptans and P. anserina, responded similarly to the local quality of their environment by decreasing their internode length in response to nutrient-rich soil. Only P. reptans responded to resource variability by decreasing its internode length. In both species, the experience acquired by older ramets influenced the plastic response of new rooted ramets: the internode length between ramets depended not only on the soil quality locally sampled but also on the soil quality previously sampled by older ramets. We quantified the effect of the information perceived at different time and space on the foraging behavior of clonal plants by showing a non-linear response of the ramet rooting in the soil of a given quality. These data suggest that the decision to grow a stolon or to root a ramet at a given distance from the older ramet results from the integration of the past and present information about the richness and the variability of the environment.

  12. Thermodynamic properties of water desorption of forage turnip seeds

    OpenAIRE

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

    2014-01-01

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

  13. Thermodynamic properties of water desorption of forage turnip seeds

    OpenAIRE

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

    2015-01-01

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

  14. Information Foraging Theory: A Framework for Intelligence Analysis

    Science.gov (United States)

    2014-11-01

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

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

    OpenAIRE

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

    2001-01-01

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

  16. 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.

  17. 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...

  18. Adaptive collective foraging in groups with conflicting nutritional needs

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  20. Habitat-specific foraging strategies in Australasian gannets.

    Science.gov (United States)

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

    2016-07-15

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

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

    Science.gov (United States)

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

    2015-10-01

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

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

    OpenAIRE

    Ludynia, Katrin

    2007-01-01

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

  3. 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.

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    James K. Wetterer

    1995-01-01

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

  6. 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.

  7. Impacts of Different Stages of Nitrogen Dressing on Feeding Value of Forage Summer Maize

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-wang; WANG Kong-jun; HU Chang-hao; DONG Shu-ting; LIU Peng

    2002-01-01

    A trial of investigating impacts of nitrogen dressing at different stage on feeding value and physiological characteristics of forage summer maize (Ludan50) has been conducted by means of potted planting. The results suggested that biomass yield, grains yield and feeding value of all treatments were significantly raised compared CK without nitrogen dressing. Nitrogen dressing at the jointing stage for one time could raise the dry matter yield in terms of biomass, thus improving feeding value. Separating total dose of dressing nitrogen into two or three times at the jointing, male tetrad (or flowering) stage were beneficial to the dual purpose of maize, i.e. both kernel and forage. The effects on physiological characters were reflected as the improvement of leaf area index (LAI), activity of nitrate reductase (NR), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD)and soluble protein content in leave above ear. Such impacts were more obvious at the late stage of maize growth.

  8. 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...

  9. Forage polyphenol oxidase and ruminant livestock nutrition.

    Science.gov (United States)

    Lee, Michael R F

    2014-01-01

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

  10. 75 FR 68321 - Forage Genetics International; Supplemental Request for Partial Deregulation of Roundup Ready...

    Science.gov (United States)

    2010-11-05

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

  11. Valorisation of compost from cattle manure in forage plant cultures

    Directory of Open Access Journals (Sweden)

    Benoni Lixandru

    2014-05-01

    Full Text Available Two successive agricultural years was investigated the effect of fertilizer on forage production of compost from cattle manure aerobic fermentation. For this, were experienced two types of compost with cellulosic support coming from: the stalks chopped sunflower and triticale straw. The type of compost from the two studied recipes did not affect the production of green mass. The fertilizer effect was influenced by the dose of compost administered per unit area, production growth being of 14 t green mass·ha-1 at a dose of 50 t compost·ha-1 and 10 t green mass·ha-1 at a dose of 30 t compost·ha-1. Following the fertilization repeated in the second year, production growth was low, being higher by just 1.7 – 3 % on plots fertilized with 30 t compost·ha-1, respectively, 1.1 – 1.3 % on plots fertilized with 50 t compost·ha-1.

  12. 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.

  13. Arctic warming: nonlinear impacts of sea-ice and glacier melt on seabird foraging.

    Science.gov (United States)

    Grémillet, David; Fort, Jérôme; Amélineau, Françoise; Zakharova, Elena; Le Bot, Tangi; Sala, Enric; Gavrilo, Maria

    2015-03-01

    Arctic climate change has profound impacts on the cryosphere, notably via shrinking sea-ice cover and retreating glaciers, and it is essential to evaluate and forecast the ecological consequences of such changes. We studied zooplankton-feeding little auks (Alle alle), a key sentinel species of the Arctic, at their northernmost breeding site in Franz-Josef Land (80°N), Russian Arctic. We tested the hypothesis that little auks still benefit from pristine arctic environmental conditions in this remote area. To this end, we analysed remote sensing data on sea-ice and coastal glacier dynamics collected in our study area across 1979-2013. Further, we recorded little auk foraging behaviour using miniature electronic tags attached to the birds in the summer of 2013, and compared it with similar data collected at three localities across the Atlantic Arctic. We also compared current and historical data on Franz-Josef Land little auk diet, morphometrics and chick growth curves. Our analyses reveal that summer sea-ice retreated markedly during the last decade, leaving the Franz-Josef Land archipelago virtually sea-ice free each summer since 2005. This had a profound impact on little auk foraging, which lost their sea-ice-associated prey. Concomitantly, large coastal glaciers retreated rapidly, releasing large volumes of melt water. Zooplankton is stunned by cold and osmotic shock at the boundary between glacier melt and coastal waters, creating new foraging hotspots for little auks. Birds therefore switched from foraging at distant ice-edge localities, to highly profitable feeding at glacier melt-water fronts within <5 km of their breeding site. Through this behavioural plasticity, little auks maintained their chick growth rates, but showed a 4% decrease in adult body mass. Our study demonstrates that arctic cryosphere changes may have antagonistic ecological consequences on coastal trophic flow. Such nonlinear responses complicate modelling exercises of current and future

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

    Science.gov (United States)

    Kumar, Anjali; O'Donnell, Sean

    2009-01-01

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

  15. Modeling ventilation time in forage tower silos.

    Science.gov (United States)

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

    2012-10-01

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

  16. Threshold foraging behavior of baleen whales

    Science.gov (United States)

    Piatt, John F.; Methven, David A.

    1992-01-01

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

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

    Science.gov (United States)

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

  18. Yield and forage nutritive value of reduced lignin alfalfa

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    1992-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-08-01

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

  2. 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…

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

    DEFF Research Database (Denmark)

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2005-12-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  9. FORAGE AND GRAIN YIELD PERFORMANCES OF SOYBEAN LINES

    Directory of Open Access Journals (Sweden)

    Ugur BILGILI

    2006-05-01

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

  10. Linking foraging decisions to residential yard bird composition.

    Directory of Open Access Journals (Sweden)

    Susannah B Lerman

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

  11. Linking foraging decisions to residential yard bird composition.

    Science.gov (United States)

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

    2012-01-01

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

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  13. Forage mass and stocking rate of elephant grass pastures managed under agroecological and conventional systems

    Directory of Open Access Journals (Sweden)

    Clair Jorge Olivo

    2014-06-01

    Full Text Available The objective was to evaluate elephant grass (Pennisetum purpureum Schum. pastures, under the agroecological and conventional systems, as forage mass and stocking rate. In the agroecological system, the elephant grass was established in rows spaced by 3.0 m from each other. During the cool season ryegrass (Lolium multiflorum Lam. was established between these rows, which allowed the development of spontaneous growth species during the warm season. In the conventional system the elephant grass was established singularly in rows spaced 1.4 m from each other. Organic and chemical fertilizers were applied at 150 kg of N/ha/year with in the pastures under agroecological and conventional systems, respectively. Lactating Holstein cows which received 5.0 kg/day supplementary concentrate feed were used for evaluation. The experimental design was completely randomized, with two treatments (agroecological and conventional systems two replications (paddocks and independent evaluations (grazing cycles. The pastures were used during the whole year for the agroecological system and for 195 days in the conventional year. The average values of forage mass were 3.5 and 4.2 t/ha and the stocking rates were 2.08 and 3.23 AU/ha for the respective systems. The results suggest that the use of the elephant grass under the agroecological system allows for best distribution of forage and stocking rate to be more uniform throughout the year than the use of elephant grass in conventional system.

  14. 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.

  15. Improving the lipid nutritive value of poultry meat through the incorporation of a dehydrated leguminous-based forage in the diet for broiler chicks.

    Science.gov (United States)

    Ponte, P I P; Prates, J A M; Crespo, J P; Crespo, D G; Mourão, J L; Alves, S P; Bessa, R J B; Chaveiro-Soares, M A; Ferreira, L M A; Fontes, C M G A

    2008-08-01

    Dehydrated forages are assumed to be good sources of alpha-linolenic acid (ALA) and lipid-soluble antioxidant compounds (vitamin E homologs and beta-carotene). The effects of including a dehydrated leguminous-based forage in a typical diet for broiler chicken, on performance, meat quality, and fatty acid composition were evaluated. One hundred sixty 1-d-old male commercial broiler chicks (Ross 308) were housed in 20 battery brooders. During the 28-d growth period, the animals were fed ad libitum with a typical maize-soybean high-energy feed having access or not to a dehydrated leguminous-based forage provided in a separate feeder. The results revealed that dehydrated forage intake (which was 11.1% of the total intake) had no impact in broiler performance (P > 0.05). The capacity of ingested forage to modulate broiler meat fatty acid profile and the meat content in total cholesterol, tocopherols, tocotrienols, and beta-carotene was investigated in broiler chicks slaughtered at d 28. Dehydrated forage consumption had no effect on the lipid-soluble antioxidant compounds and cholesterol contents of broiler meat but had a significant effect on meat fatty acid profile. Although forage intake did not affect the linoleic acid and ALA contents in poultry meat, the levels of n-3 long-chain polyunsaturated fatty acids [eicosapentaenoic (P = 0.004), docosapentaenoic (P = 0.010), and docosahexaenoic (P = 0.007)] in breast meat were significantly higher in animals consuming leguminous biomass, which suggest a higher conversion of ALA into its derivatives in these birds. Overall, the data confirms that incorporation of a dehydrated leguminous-based forage in the diet for broiler chicks results in more favorable polyunsaturated fatty acids/saturated fatty acids and n-6/n-3 nutritional ratios for animals slaughtered at earlier stages of grow.

  16. 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.

  17. Stature in Holocene foragers of North India.

    Science.gov (United States)

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

    2014-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Samantha C Patrick

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

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

    Science.gov (United States)

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

    2015-05-01

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

  20. Growing tropical forage legumes in full sun and silvopastoral systems

    Directory of Open Access Journals (Sweden)

    Saulo Alberto do Carmo Araújo

    2017-02-01

    Full Text Available Growth was evaluated three tropical forage legumes in two cropping systems: silvopastoral system (SSP and full sun. A completely randomized design was adopted in factorial three legumes (estilosanthes cv. Campo Grande (Stylozanthes macrocephala x Stylozanthes capitata, tropical kudzu (Pueraria phaseoloides (Roxb. Benth and macrotiloma (Macrotyloma axillare cv. Java x two farming systems, with 4 repetitions. A eucalyptus SSP already deployed, with spatial arrangement of 12 x 2 m between trees was used. Legumes were planted in January 2014 a uniform cut being made in May 2014. The court assessment was carried out 125 days after the uniformity cut. There was difference for mass production of dry legumes (PMMSL between cultivation systems, evidencing increased productivity in the farming full sun. The macrotiloma showed higher PMSL (5.29 kg DM ha-1 cut-1, while the kudzu obtained the lowest yield (3.42 kg DM ha-1 cut-1 in the sun growing full. The cultivation of legumes in SSP increased the levels of mineral matter, crude protein and neutral detergent fiber. The shade provided by the SSP caused a reduction in the mass of dry matter production, but also altered the chemical composition of the studied legumes.

  1. Departure time influences foraging associations in little penguins.

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2001-01-01

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

  3. 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

  4. Experimental Study of the Dynamics of Foraging Ants

    Science.gov (United States)

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

    2006-03-01

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

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

    Science.gov (United States)

    Tschinkel, Walter R

    2011-01-01

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

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

    NARCIS (Netherlands)

    Drescher, M.F.

    2003-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Science.gov (United States)

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

  9. Where to Forage in the Absence of Sea Ice? Bathymetry As a Key Factor for an Arctic Seabird.

    Directory of Open Access Journals (Sweden)

    Françoise Amélineau

    Full Text Available The earth is warming at an alarming rate, especially in the Arctic, where a marked decline in sea ice cover may have far-ranging consequences for endemic species. Little auks, endemic Arctic seabirds, are key bioindicators as they forage in the marginal ice zone and feed preferentially on lipid-rich Arctic copepods and ice-associated amphipods sensitive to the consequences of global warming. We tested how little auks cope with an ice-free foraging environment during the breeding season. To this end, we took advantage of natural variation in sea ice concentration along the east coast of Greenland. We compared foraging and diving behaviour, chick diet and growth and adult body condition between two years, in the presence versus nearby absence of sea ice in the vicinity of their breeding site. Moreover, we sampled zooplankton at sea when sea ice was absent to evaluate prey location and little auk dietary preferences. Little auks foraged in the same areas both years, irrespective of sea ice presence/concentration, and targeted the shelf break and the continental shelf. We confirmed that breeding little auks showed a clear preference for larger copepod species to feed their chick, but caught smaller copepods and nearly no ice-associated amphipod when sea ice was absent. Nevertheless, these dietary changes had no impact on chick growth and adult body condition. Our findings demonstrate the importance of bathymetry for profitable little auk foraging, whatever the sea-ice conditions. Our investigations, along with recent studies, also confirm more flexibility than previously predicted for this key species in a warming Arctic.

  10. Where to Forage in the Absence of Sea Ice? Bathymetry As a Key Factor for an Arctic Seabird

    Science.gov (United States)

    Amélineau, Françoise; Grémillet, David; Bonnet, Delphine; Le Bot, Tangi; Fort, Jérôme

    2016-01-01

    The earth is warming at an alarming rate, especially in the Arctic, where a marked decline in sea ice cover may have far-ranging consequences for endemic species. Little auks, endemic Arctic seabirds, are key bioindicators as they forage in the marginal ice zone and feed preferentially on lipid-rich Arctic copepods and ice-associated amphipods sensitive to the consequences of global warming. We tested how little auks cope with an ice-free foraging environment during the breeding season. To this end, we took advantage of natural variation in sea ice concentration along the east coast of Greenland. We compared foraging and diving behaviour, chick diet and growth and adult body condition between two years, in the presence versus nearby absence of sea ice in the vicinity of their breeding site. Moreover, we sampled zooplankton at sea when sea ice was absent to evaluate prey location and little auk dietary preferences. Little auks foraged in the same areas both years, irrespective of sea ice presence/concentration, and targeted the shelf break and the continental shelf. We confirmed that breeding little auks showed a clear preference for larger copepod species to feed their chick, but caught smaller copepods and nearly no ice-associated amphipod when sea ice was absent. Nevertheless, these dietary changes had no impact on chick growth and adult body condition. Our findings demonstrate the importance of bathymetry for profitable little auk foraging, whatever the sea-ice conditions. Our investigations, along with recent studies, also confirm more flexibility than previously predicted for this key species in a warming Arctic. PMID:27438790

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

    Science.gov (United States)

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

    2014-12-01

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

  12. Dynamics of forage accumulation in Elephant grass subjected to rotational grazing intensities

    Directory of Open Access Journals (Sweden)

    Braulio Maia de Lana Sousa

    2013-09-01

    Full Text Available We assessed the accumulation dynamics of forage and its components in Elephant grass cv. Napier (Pennisetum purpureum Schum. that were subjected to three post-grazing height treatments (30, 50, and 70 cm from February through May 2009 (experiment one and December 2009 through May 2010 (experiment two. In experiment one, the grazing events started when the light interception by the canopy reached 95%. The same was adopted for experiment two, except for the first grazing event, which was based on the height of the apical meristems of basal tillers. The experimental design for both experiments was a randomized complete block with three replications. The pastures that were managed at a post-grazing height of 30 cm exhibited lower rates of leaf and stem growth, total growth and forage accumulation than those that were managed at 50 or 70 cm, indicating that post-grazing height affects Elephant grass. The pastures that were managed at 50 cm exhibited relatively stable accumulation rates and less stem accumulation. Pastures managed at 70 cm of pos-grazing height presented more leaf and stem accumulation. Most apical meristems of Elephant grass should be removed in the first grazing when they reach the post-grazing target height of 50 cm. The elevation in the residual post-grazing height, especially in the summer, raises the regrowth vigor in the Elephant grass cv. Napier pasture. The post-grazing height of 30 cm reduces the growth of the Elephant grass cv. Napier.

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

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    Matthew J Oliver

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

  14. Traffic noise reduces foraging efficiency in wild owls

    Science.gov (United States)

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

    2016-08-01

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

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

    National Research Council Canada - National Science Library

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

    2017-01-01

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

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

    African Journals Online (AJOL)

    NORBERT OPIYO AKECH

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

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

    African Journals Online (AJOL)

    Novin

    2012-07-17

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

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

    African Journals Online (AJOL)

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

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

    African Journals Online (AJOL)

    Mo

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

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

    Directory of Open Access Journals (Sweden)

    Sajimin

    2011-06-01

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

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

    African Journals Online (AJOL)

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

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

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

    CERN Document Server

    Tejera, F

    2015-01-01

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

  4. Experimental cultivation of a new forage species - Silphium perfoliatum L. - in the Agrobotanical Garden from Cluj-Napoca

    OpenAIRE

    1985-01-01

    Based on results of Niqueux (1981) Silphium perfoliatum (Asteroideae, Heliantheae) germplasm preserved in our garden was used for the introduction of this newly emerging forage species in experimental cultivation. As generative reproduction proved to be allowed, plants were reproduced by rhizomes. The influence of bud number per rhizome, fertilization and the inclination of the plot on the growth dynamics and production were studied. Plots were harvested in 1983 and 1984 for silage and seed. ...

  5. The influence of arbuscular mycorrhizae on root precision nutrient foraging of two pioneer plant species during early reclamation

    Science.gov (United States)

    Boldt-Burisch, Katja; Naeth, M. Anne

    2017-04-01

    On many post mining sites in the Lusatian Mining District (East Germany) soil heterogeneity consists of sandy soil with embedded clay-silt fragments. Those clays silt fragments might act as nutrient hotspots. Arbuscular mycorrhizal fungi in an infertile ecosystem could enhance a plant's ability to selectively forage for those nutrients and thus to improve plants nutrient supply. In our study we investigated whether silt-clay fragments within a sandy soil matrix induced preferential root growth of Lotus corniculatus and Calamagrostis epigeios, whether arbuscular mycorrhizae influenced root foraging patterns, and to what extent selective rooting in clay silt fragments influenced plant growth were addressed in this research. Soil types were sterile and non-sterile sandy soil and clay-silt fragments. Treatments were with and without arbuscular mycorrhizae, with and without soil solution, and soil solution and mycorrhizal inoculum combined. Root biomass, root density and intraradical fungal alkaline phosphatase activity and frequency were determined in fragments relative to sandy soil. Furthermore, temporal relationship of number of roots in fragments and plant height was assessed. Lotus corniculatus showed strong selective rooting into fragments especially with those plants treated with commercial cultivated arbuscular mycorrhizae; Calamagrostis epigeios did not. Without arbuscular mycorrhizae, L. corniculatus growth was significantly reduced and selective rooting did not occur. Selective rooting induced significant growth spurts of L. corniculatus. Roots in fragments had higher fungal alkaline phosphatase activity suggesting that mycorrhizal efficiency and related plants phosphorus supply is enhanced in roots in fragments. The application of cultivated arbuscular mycorrhizal fungi significantly and quickly influenced root foraging patterns, especially those of L. corniculatus, suggesting mycorrhizae may also enhance the ability of other plants to selectively forage

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

    Science.gov (United States)

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

    2010-02-10

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

  7. 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.

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

    Science.gov (United States)

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

    2013-01-01

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

  9. Flexible Foraging of Ants under Unsteadily Varying Environment

    Science.gov (United States)

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

    2004-08-01

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

  10. On methodology of foraging behavior of pollinating insects

    OpenAIRE

    Yanbing Gong; Shuangquan Huang

    2007-01-01

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

  11. 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.

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

    Directory of Open Access Journals (Sweden)

    Alejandro Moreno-Reséndez

    2017-01-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  14. 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.

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

    Science.gov (United States)

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

    2014-06-10

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

  16. Chaos–order transition in foraging behavior of ants

    Science.gov (United States)

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

    2014-01-01

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

  17. 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).

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

    2014-01-01

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

  20. 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.

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

    Science.gov (United States)

    Guénard, Benoit; Silverman, Jules

    2011-08-01

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

  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. 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.

  4. Leaf Length Variation in Perennial Forage Grasses

    Directory of Open Access Journals (Sweden)

    Philippe Barre

    2015-08-01

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

  5. Color and polarization vision in foraging Papilio.

    Science.gov (United States)

    Kinoshita, Michiyo; Arikawa, Kentaro

    2014-06-01

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

  6. Simultaneous brightness contrast of foraging Papilio butterflies.

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-05-22

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

  7. Combining near infrared spectra of feces and geostatistics to generate forage nutritional quality maps across landscapes.

    Science.gov (United States)

    Pierre-Olivier, Jean; Bradley, Robert L; Tremblay, Jean-Pierre; Côté, Steeve D

    2015-09-01

    An important asset for the management of wild ungulates is recognizing the spatial distribution of forage quality across heterogeneous landscapes. To do so typically requires knowledge of which plant species are eaten, in what abundance they are eaten, and what their nutritional quality might be. Acquiring such data, however, may be difficult and time consuming. Here, we are proposing a rapid and cost-effective forage quality monitoring tool that combines near infrared (NIR) spectra of fecal samples and easily obtained data on plant community composition. Our approach rests on the premise that NIR spectra of fecal samples collected within low population density exclosures reflect the optimal forage quality of a given landscape. Forage quality can thus be based on the Mahalanobis distance of fecal spectral scans across the landscape relative to fecal spectral scans inside exclosures (referred to as DISTEX). The Gi* spatial autocorrelation statistic can then be applied among neighboring DISTEX values to detect and map "hot spots" and "cold spots" of nutritional quality over the landscape. We tested our approach in a heterogeneous boreal landscape on Anticosti Island (Québec, Canada), where white-tailed deer (Odocoileus virginianus) populations over the landscape have ranged from 20 to 50 individuals/km2 for at least 80 years, resulting in a loss of most palatable and nutritious plant species. Our results suggest that hot spots of forage quality occur when old-growth balsam fir stands comprise >39.8% of 300 ha neighborhoods, whereas cold spots occur in laggs (i.e., transition zones from forest to peatland). In terms of ground-level indicator plant species, the presence of Canada bunchberry (Cornus canadensis) was highly correlated with hot spots, whereas tamarack (Larix laricina) was highly correlated with cold spots. Mean DISTEX values were positively and significantly correlated with the neutral detergent fiber and acid detergent lignin contents of feces. While our

  8. The effects of food presentation and microhabitat upon resource monopoly in a ground-foraging ant (Hymenoptera: Formicidae) community.

    Science.gov (United States)

    McGlynn, T P; Kirksey, S E

    2000-01-01

    In Neotropical wet forests several species of omnivorous, resource-defending ants, live and forage in close proximity to one another. Although the forest floor is heterogeneous in microhabitat and food quantity, little is known about the impact of microhabitat and food variation upon resource monopoly among ants. We investigated how food type and microhabitat influence food monopoly in resource-defending ants in old-growth tropical wet forest in the Caribbean lowlands of Costa Rica. We measured several microhabitat characteristics at 66 points in a 0.5 hectare plot, and baited each point with two categories of tuna bait. These baits were presented in "split" and "clumped" arrangements. We measured the frequency of bait monopoly by a single species, as well as the number of recruited ant foragers at a bait. Out of five common species, two (Wasmannia auropunctata and Pheidole simonsi) more frequently monopolized one bait type over the other, and one (P. simonsi) recruited more ants to the split baits. We then considered the recruitment response by all ant species in the community. We found that the frequency of monopoly, sharing, and the absence of ants at a given point in the rainforest differed with bait type. The frequency of monopoly was associated with microhabitat type in two out of eight microhabitat variables (leaf litter depth and palms); variation in two other types (canopy tree distance and leafcutter ant trails) was associated with changes in forager number. In at least two ant species, food presentation affected monopoly at baits; among all resource-defending ants, the microhabitats where ants foraged for food and the type of food located determined in part the frequency of monopoly and the number of foragers at the food item. These results suggest that the location and presentation of food items determines in part which ant species will utilize the resource.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Deborah M Gordon

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

  11. Hybrid Artificial Root Foraging Optimizer Based Multilevel Threshold for Image Segmentation

    Science.gov (United States)

    Liu, Yang; Liu, Junfei

    2016-01-01

    This paper proposes a new plant-inspired optimization algorithm for multilevel threshold image segmentation, namely, hybrid artificial root foraging optimizer (HARFO), which essentially mimics the iterative root foraging behaviors. In this algorithm the new growth operators of branching, regrowing, and shrinkage are initially designed to optimize continuous space search by combining root-to-root communication and coevolution mechanism. With the auxin-regulated scheme, various root growth operators are guided systematically. With root-to-root communication, individuals exchange information in different efficient topologies, which essentially improve the exploration ability. With coevolution mechanism, the hierarchical spatial population driven by evolutionary pressure of multiple subpopulations is structured, which ensure that the diversity of root population is well maintained. The comparative results on a suit of benchmarks show the superiority of the proposed algorithm. Finally, the proposed HARFO algorithm is applied to handle the complex image segmentation problem based on multilevel threshold. Computational results of this approach on a set of tested images show the outperformance of the proposed algorithm in terms of optimization accuracy computation efficiency. PMID:27725826

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Science.gov (United States)

    Deluycker, Anneke M

    2012-05-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2009-12-01

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

  16. Nonlinear relationships can lead to bias in biomass calculations and drift-foraging models when using summaries of invertebrate drift data

    Science.gov (United States)

    Dodrill, Michael J.; Yackulic, Charles B.

    2016-01-01

    Drift-foraging models offer a mechanistic description of how fish feed in flowing water and the application of drift-foraging bioenergetics models to answer both applied and theoretical questions in aquatic ecology is growing. These models typically include nonlinear descriptions of ecological processes and as a result may be sensitive to how model inputs are summarized because of a mathematical property of nonlinear equations known as Jensen’s inequality. In particular, we show that the way in which continuous size distributions of invertebrate prey are represented within foraging models can lead to biases within the modeling process. We begin by illustrating how different equations common to drift-foraging models are sensitive to invertebrate inputs. We then use two case studies to show how different representations of invertebrate prey can influence predictions of energy intake and lifetime growth. Greater emphasis should be placed on accurate characterizations of invertebrate drift, acknowledging that inferences from drift-foraging models may be influenced by how invertebrate prey are represented.

  17. Neutron activation analysis application for determining iron concentration in forage grasses used in intensive cattle production system; Aplicacao da analise por ativacao com neutrons para determinacao de ferro em forrageiras usadas no sistema intensivo de producao de bovinos de leite

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria Jose A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Primavesi, Odo [Empresa Brasileira de Pesquisa Agropecuaria, Sao Carlos, SP (Brazil). Centro de Pesquisa de Pecuaria do Sudeste

    2002-07-01

    Iron is an essential element to the life. It is an important hemoglobin component and it is involved in the transport of oxygen to cells. A deficiency of iron results in an unsuitable synthesis of hemoglobin and a delay in the growth. Iron contents above the tolerable level in animal feed can cause serious damages to the health and the death in extreme cases. The forages are the main source of feed to cattle in grazing. It is known from the literature, that the growth and the nutritious value of the forage are influenced by specie and physiologic age of the plant, soil fertility and environmental conditions. Therefore, an agronomical evaluations of the forages are necessary before to introduce in an intensive cattle production systems to program adequate grazing management. Neutron activation analysis was applied to evaluate the Fe concentration in the main tropical forage grasses used in intensive dairy cattle production systems in Sao Carlos, SP, Brazil. Iron concentrations were smaller in the rain season than in the dry one. Comparison of results obtained in the analyses of forages with daily requirements of iron in dry matter, showed that the Fe concentration in forages was adequate. (author)

  18. Honey bee foraging ecology: Season but not landscape diversity shapes the amount and diversity of collected pollen.

    Science.gov (United States)

    Danner, Nadja; Keller, Alexander; Härtel, Stephan; Steffan-Dewenter, Ingolf

    2017-01-01

    The availability of pollen in agricultural landscapes is essential for the successful growth and reproduction of honey bee colonies (Apis mellifera L.). The quantity and diversity of collected pollen can influence the growth and health of honey bee colonies, but little is known about the influence of landscape structure on pollen diet. In a field experiment, we rotated 16 honey bee colonies across 16 agricultural landscapes, used traps to collect samples of collected pollen and observed intra-colonial dance communication to gain information about foraging distances. DNA metabarcoding was applied to analyze mixed pollen samples. Neither the amount of collected pollen nor pollen diversity was related to landscape diversity. However, we found a strong seasonal variation in the amount and diversity of collected pollen in all sites independent of landscape diversity. The observed increase in foraging distances with decreasing landscape diversity suggests that honey bees compensated for lower landscape diversity by increasing their pollen foraging range in order to maintain pollen amount and diversity. Our results underscore the importance of a diverse pollen diet for honey bee colonies. Agri-environmental schemes aiming to support pollinators should focus on possible spatial and temporal gaps in pollen availability and diversity in agricultural landscapes.

  19. Nitrogen and carbohydrate fractions on Tifton-85 pastures overseeded with annual winter and summer forage species in different seasons

    Directory of Open Access Journals (Sweden)

    Andréia Luciane Moreira

    2012-09-01

    Full Text Available An experiment was conducted during the 2001-2002 winter-spring-summer to determine the nitrogen and carbohydrate fractions in Tifton-85 pastures exclusively or overseeded with oats, millet and sorghum-sudangrass hybrids. The treatments were Tifton-85 overseeded with millet + bristle oat; sorghum-sudangrass + bristle oat, on 06/19/2002 and 07/02/2002, respectively; and Tifton-85 (Control. The experiment was conducted in a randomized block design with three replications. Nitrogen and carbohydrate fractions were affected by the nitrogen and total carbohydrate contents observed in the pasture overseeded at different seeding times, and by the different growth periods. The highest nitrogen fractions (A + B1 were observed in the early growth periods. Overseeding affected the forage nitrogen and carbohydrate fraction contents positively. The high solubility of both carbohydrate and protein from millet + bristle oat and bristle oat + sorghum-sudangrass mixtures indicates the quality of these forages and their potential use as an important supplement in forage systems based on tropical pastures.

  20. Using NDVI and EVI to Map Spatiotemporal Variation in the Biomass and Quality of Forage for Migratory Elk in the Greater Yellowstone Ecosystem

    Directory of Open Access Journals (Sweden)

    Erica L. Garroutte

    2016-05-01

    Full Text Available The Normalized Difference Vegetation Index (NDVI and the Enhanced Vegetation Index (EVI have gained considerable attention in ecological research and management as proxies for landscape-scale vegetation quantity and quality. In the Greater Yellowstone Ecosystem (GYE, these indices are especially important for mapping spatiotemporal variation in the forage available to migratory elk (Cervus elaphus. Here, we examined how the accuracy of using MODIS-derived NDVI and EVI as proxies for forage biomass and quality differed across elevation-related phenology and land use gradients, determined if polynomial NDVI/EVI, site, and season effects improved these models, and then mapped spatiotemporal variation in the abundance of high quality forage available to elk across the Upper Yellowstone River Basin (UYRB of the GYE. Models with a polynomial NDVI effect explained 19%–55% more variation in biomass than the linear NDVI and EVI models. Models with linear season effect explained 14%–20% more variation in chlorophyll, 37%–69% more variation in crude protein, and 26%–50% more variation in in vitro dry matter digestibility (IVDMD than the linear NDVI and EVI models. Linear NDVI models explained more variation in biomass and quality across the UYRB than the linear EVI models. The accuracy of these models was lowest in grasslands with late onset of growth, in irrigated agriculture, and after the peak in biomass. Forage biomass and quality varied across the elevation-related phenology and land use gradients in the UYRB throughout the season. At their seasonal peak, the abundance of high quality forage for elk was 50% greater in grasslands with late onset of growth and 200% greater in irrigated agriculture than in all other grasslands, suggesting that these grasslands play an especially important role in the movement and fitness of migratory elk. These results provide novel information on the utility of NDVI and EVI for mapping spatiotemporal patterns of

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

    Science.gov (United States)

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

    2015-12-21

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

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

    Science.gov (United States)

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

    2016-09-25

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

  3. Analysis of adaptive foraging in an intraguild predation system

    Directory of Open Access Journals (Sweden)

    T. Okuyama

    2003-09-01

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

  4. Experimental cultivation of a new forage species - Silphium perfoliatum L. - in the Agrobotanical Garden from Cluj-Napoca

    Directory of Open Access Journals (Sweden)

    Ioan PUIA

    1985-08-01

    Full Text Available Based on results of Niqueux (1981 Silphium perfoliatum (Asteroideae, Heliantheae germplasm preserved in our garden was used for the introduction of this newly emerging forage species in experimental cultivation. As generative reproduction proved to be allowed, plants were reproduced by rhizomes. The influence of bud number per rhizome, fertilization and the inclination of the plot on the growth dynamics and production were studied. Plots were harvested in 1983 and 1984 for silage and seed. The average production of hay in one cut was 6,7 t/ha in 1983 and 6,3 t/ha in 1984. The best plot yiealded 15,7 (1983 and 10,8 t/ha hay. Average seed yield was in 1984: 587 kg/ha, the highest yield was 1265 kg/ha. In so far as we know, this is the first introduction of the species in cultivation for economic purposes (forage or biomass in Romania.

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

    Science.gov (United States)

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

    2013-01-01

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

  6. Monitoring digestibility of forages for herbivores: a new application for an old approach

    Science.gov (United States)

    VanSomeren, LIndsey L.; Barboza, Perry S.; Thompson, Daniel P.; Gustine, David D.

    2015-01-01

    Ruminant populations are often limited by how well individuals are able to acquire nutrients for growth, maintenance, and reproduction. Nutrient supply to the animal is dictated by the concentration of nutrients in feeds and the efficiency of digesting those nutrients (i.e., digestibility). Many different methods have been used to measure digestibility of forages for wild herbivores, all of which rely on collecting rumen fluid from animals or incubation within animals. Animal-based methods can provide useful estimates, but the approach is limited by the expense of fistulated animals, wide variation in digestibility among animals, and contamination from endogenous and microbial sources that impairs the estimation of nutrient digestibility. We tested an in vitro method using a two-stage procedure using purified enzymes. The first stage, a 6 h acid–pepsin treatment, was followed by a combined 72 h amylase–cellulase or amylase–Viscozyme treatment. We then validated our estimates using in sacco and in vivo methods to digest samples of the same forages. In vitro estimates of dry matter (DM) digestibility were correlated with estimates of in sacco and in vivo DM digestibility (both P < 0.01). The in vitro procedure using Viscozyme (r2 = 0.77) was more precise than the in vitro procedure using cellulase (r2 = 0.59). Both procedures can be used to predict in sacco digestibility after correcting for the biases of each method. We used the in vitro method to measure digestibility of nitrogen (N; 0.07–0.95 g/g), which declined to zero as total N content declined below 0.03–0.06 g/g of DM. The in vitro method is well suited to monitoring forage quality over multiple years because it is reproducible, can be used with minimal investment by other laboratories without animal facilities, and can measure digestibility of individual nutrients such as N.

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

    Science.gov (United States)

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

    2010-11-01

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

  8. Natal foraging philopatry in eastern Pacific hawksbill turtles.

    Science.gov (United States)

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

    2017-08-01

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

  9. 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

  10. 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.

  11. Forage herbs improve mineral composition of grassland herbage

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  12. The Müller-Lyer illusion in ant foraging.

    Science.gov (United States)

    Sakiyama, Tomoko; Gunji, Yukio-Pegio

    2013-01-01

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

  13. The Muller-Lyer illusion in ant foraging.

    Directory of Open Access Journals (Sweden)

    Tomoko Sakiyama

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  15. Evolution of Optimum Foraging Distributions in Two Dimensions

    Science.gov (United States)

    Dees, Nathan; Bahar, Sonya; Moss, Frank

    2008-03-01

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

  16. 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.

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

    Science.gov (United States)

    Bird, Douglas W; Bliege Bird, Rebecca

    2002-06-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

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

    NARCIS (Netherlands)

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

    1998-01-01

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

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

    African Journals Online (AJOL)

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

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

    National Research Council Canada - National Science Library

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2012-08-07

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

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

    Science.gov (United States)

    Gil, Mariana; Farina, Walter Marcelo

    2002-05-01

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

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

    Science.gov (United States)

    Sunagawa, Katsunori; Nagamine, Itsuki

    2016-02-01

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

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

    Science.gov (United States)

    2015-09-30

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

  6. Devclopment of the Forage Riees WithHigh Protein Gontent in Hunan

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The meaning of the high protein forage rices Rices may be classified by itsuses as human'sfood.animal's on poultry's feed,or the raw materials of various industries.For ricesused as people's food.its breeding objectives are focused on the varietal characters such as medium amylose content .high rale of head rice.hyaline smoothmilled grains and delicious taste:for those used in making rice meal.beer,gourmet powder,etc.specially on high amylose content:while in wine making,it should be focused on big white belly and white beart,but low protein content in particular.As for the rices used as feed,the most important is its high rate of pre -protein in the brown rice ,leaving its grain appearance out of consideration.Thcrefore,the so called forage rice (FR)sgiykd be a kind of paddy rice with high pre-protein content of brown rice(≥8.25%)and high grain yicld (≥8.25t/ha),to be used as the composition of the animal feed by applying cultivation management oplimized under the suitable growth duration and strong pest resistance.

  7. Contrasting strategies to cope with drought conditions by two tropical forage C4 grasses

    Science.gov (United States)

    Cardoso, Juan Andrés; Pineda, Marcela; Jiménez, Juan de la Cruz; Vergara, Manuel Fernando; Rao, Idupulapati M.

    2015-01-01

    Drought severely limits forage productivity of C4 grasses across the tropics. The avoidance of water deficit by increasing the capacity for water uptake or by controlling water loss are common responses in forage C4 grasses. Napier grass (Pennisetum purpureum) and Brachiaria hybrid cv. Mulato II are tropical C4 grasses used for livestock production due to their reputed resistance to drought conditions. However, there is scant information on the mechanisms used by these grasses to overcome water-limited conditions. Therefore, assessments of cumulative transpired water, shoot growth, leaf rolling, leaf gas exchange, dry mass production and a number of morpho-physiological traits were recorded over a period of 21 days under well-watered or drought conditions. Drought reduced shoot dry mass of both grasses by 35 %, yet each grass exhibited contrasting strategies to cope with water shortage. Napier grass transpired most available water by the end of the drought treatment, whereas a significant amount of water was still available for Mulato II. Napier grass maintained carbon assimilation until the soil was fairly dry, whereas Mulato II restricted water loss by early stomatal closure at relatively wet soil conditions. Our results suggest that Napier grass exhibits a ‘water-spending’ behaviour that might be targeted to areas with intermittent drought stress, whereas Mulato II displays a ‘water-saving’ nature that could be directed to areas with longer dry periods. PMID:26333827

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

    Directory of Open Access Journals (Sweden)

    Juanita Joseph

    2016-04-01

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

  9. To survive or to slay: Resource-foraging role of metabolites implicated in allelopathy.

    Science.gov (United States)

    Tharayil, Nishanth

    2009-07-01

    The ecological relevance of allelopathy is highly debated due to the lack of phytotoxic concentrations of allelochemical in natural field conditions. Most of the putative allelochemicals are exuded at low concentrations, and subsequently undergo rapid chemical and biological degradation in soil matrices. At sub-toxic concentrations, due to hormesis effect, these compounds could possibly have a stimulatory effect on plant growth. Many of the suggested allelopathic compounds are chelants and can complex-with and mobilize metal ions in soil. These complexation reactions will detoxify the compound, but will increase the chemical-nutrient-foraging ability of the donor plant. The concentration in which these compounds are exuded matches with other similar secondary metabolites facilitating plant nutrient acquisition. Irrespective of whether the implicated PSMs facilitate donor plant in chemical nutrient-foraging or in poisoning the neighbors, the conferred advantage translates in terms of resource availability-in first case the donor enjoys uncontested nutrient uptake efficiency, where as in the latter the donor gain an uncontested access to resources. This further reaffirms the notion that resource competition and allelopathy are inextricable. Since most of the secondary metabolites could mobilize nutrients from soil, along with its phytotoxic effect, complementary self-facilitation roles of these compounds should be investigated.

  10. 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...

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

    Science.gov (United States)

    Burton, Glenn W.

    1973-01-01

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

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

    NARCIS (Netherlands)

    Honing, van der Y.

    1975-01-01

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

  13. 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...

  14. Bacterial inoculants of forage grasses that enhance degradation of 2-chlorobenzoic acid in soil

    Energy Technology Data Exchange (ETDEWEB)

    Siciliano, S.D.; Germida, J.J. [Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada)

    1997-06-01

    Biological remediation of contaminated soil is an effective method of reducing risk to human and ecosystem health. Bacteria and plants might be used to enhance remediation of soil pollutants in situ. This study assessed the potential of bacteria, plants, and plant-bacteria associations to remediate 2-chlorobenzoic acid (2CBA) contaminated soil. Initially, grass viability was assessed in 2CBA-contaminated soil. Soil was contaminated with 2CBA, forage grasses were grown under growth chamber conditions for 42 or 60 d, and the 2CBA concentration in soil was determined by gas chromatography. Only five of 16 forage grasses grew in 2CBA-treated soil. Growth of Bromus inermis had no effect on 2CBA concentration, whereas Agropyron intermedium, B. biebersteinii, A. riparum, and Elymus dauricus decreased 2CBA relative to nonplanted control soil by 32 to 42%. The 12 bacteria isolates were screened for their ability to promote the germination of the five grasses in 2CBA-contaminated soil. Inoculation of A. riparum with Pseudomonas aeruginosa strain R75, a proven plant growth-promoting rhizobacterium, increased seed germination by 80% and disappearance of 2CBA by 20% relative to noninoculated plants. Inoculation of E. dauricus with a mixture of P. savastanoi strain CB35, a 2CBA-degrading bacterium, and P. aeruginosa strain R75 increased disappearance of 2CBA by 112% relative to noninoculated plants. No clear relationship between enhanced 2CBA disappearance and increased plant biomass was found. These results suggest that specific plant-microbial systems can be developed to enhance remediation of pollutants in soil.

  15. Development of foraging skills in two orangutan populations: needing to learn or needing to grow?

    Science.gov (United States)

    Schuppli, Caroline; Forss, Sofia I F; Meulman, Ellen J M; Zweifel, Nicole; Lee, Kevin C; Rukmana, Evasari; Vogel, Erin R; van Noordwijk, Maria A; van Schaik, Carel P

    2016-01-01

    Orangutans have one of the slowest-paced life histories of all mammals. Whereas life-history theory suggests that the time to reach adulthood is constrained by the time needed to reach adult body size, the needing-to-learn hypothesis instead suggests that it is limited by the time needed to acquire adult-level skills. To test between these two hypotheses, we compared the development of foraging skills and growth trajectories of immature wild orangutans in two populations: at Tuanan (Pongo pygmaeus wurmbii), Borneo, and Suaq Balimbing (Pongo abelii), Sumatra. We collected behavioral data on diet repertoire, feeding rates and ranging competence during focal follows, and estimated growth through non-invasive laser photogrammetry. We found that adult-like diet repertoires are attained around the age of weaning and that female immatures increase their repertoire size faster than their male peers. Adult-level feeding rates of easy techniques are reached just after weaning, but several years later for more difficult techniques, albeit always before adulthood (i.e. age at first reproduction). Independent immatures had faster feeding rates for easy to process items than their mothers, with male immatures achieving faster feeding rates earlier in development relative to females. Sumatran immatures reach adult-level feeding rates 2-3 years later than their Bornean peers, in line with their higher dietary complexity and later weaning. The range-use competence of independently ranging and weaned immatures is similar to that of adult females. Body size measurements showed, immatures grow until female age of first reproduction. In conclusion, unlike in humans, orangutan foraging skills are in place prior to reproduction. Growth trajectories suggest that energetic constraints, rather than skills, best explain the length of immaturity. However, skill competence for dietary independence is reached later where the adult niche is more complex, which is consistent with the relatively

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

    Science.gov (United States)

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

    2011-09-01

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

  17. 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.

  18. Selection of foraging habitat and diet of the Hoopoe Upupa epops in the mosaic-like cultural landscape of Goričko (NE Slovenia

    Directory of Open Access Journals (Sweden)

    Podletnik Mojca

    2015-12-01

    Full Text Available In 2012 and 2013, the selection of foraging habitats and the diet of the Hoopoe Upupa epops were studied in the Goričko area, where a significant population decline of the species has been recorded in the past 15 years. Goričko is an area with a well-preserved traditional mosaic-like agricultural landscape very rich in biodiversity which, however, is disappearing. The diet was determined using automatic camera recordings of prey brought to chicks by parents. Mole crickets Gryllotalpa gryllotalpa were the most dominant prey (35.4% frequency and 81.3% biomass of prey, followed by Scarab beetles larvae Scarabaeidae, caterpillars Lepidoptera larvae and True flies Diptera. Feeding frequency was highest in the period of most intensive chick growth (between 8 and 21 days of age. Selection of foraging habitat was researched by observation of birds during foraging. Hoopoes foraged mostly in mown meadows and grassy courtyards and, to a lesser extent, on sandy cart tracks and road edges. These habitats were characterized by low vegetation and patches of bare ground that enabled Hoopoes to forage efficiently. Home range size was determined using minimum convex polygons. The maximum home range size was between 42.9 and 57.7 ha, while the percentage of foraging habitats within the home range did not exceed 18%. Based on our results, we propose the following measures for effective Hoopoe conservation in the area: maintaining the present range of existing unimproved meadows, stopping the conversion of meadows into fields, restoring fields to meadows, prohibiting the use of pesticides targeting Mole crickets.

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

    Science.gov (United States)

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

    2017-01-01

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

  20. Pollen collection and honey bee forager distribution in cantaloupe

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Pavlína Hloucalová

    2016-07-01

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

  2. Cervid forage utilization in noncommercially thinned ponderosa pine forests

    Science.gov (United States)

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

    2004-01-01

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

  3. Thermodynamic properties of water desorption of forage turnip seeds

    Directory of Open Access Journals (Sweden)

    Kelly Aparecida Sousa

    2014-11-01

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

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

    DEFF Research Database (Denmark)

    Ahrenfeldt, Erica Juel

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

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

    Science.gov (United States)

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

    2016-09-01

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

  6. Use of Urban Marine Habitats by Foraging Wading Birds

    Science.gov (United States)

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

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

    Science.gov (United States)

    Toyokawa, Wataru

    2017-03-01

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

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

    NARCIS (Netherlands)

    Verboom, B.

    1998-01-01

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

  9. At-sea associations in foraging little penguins.

    Science.gov (United States)

    Berlincourt, Maud; Arnould, John P Y

    2014-01-01

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

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  11. Predation risk and elk-aspen foraging patterns

    Science.gov (United States)

    Clifford A. White; Michael C. Feller

    2001-01-01

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

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

    NARCIS (Netherlands)

    Verboom, B.

    1998-01-01

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

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

    African Journals Online (AJOL)

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

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

    Science.gov (United States)

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

    2010-10-01

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

  15. Improving Pervasive Positioning through Three-tier Cyber Foraging

    DEFF Research Database (Denmark)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

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

    Science.gov (United States)

    Whalley, W. Brian

    2016-01-01

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

  18. The Role of Semantic Clustering in Optimal Memory Foraging

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

  20. Foraging behavior and virulence of some entomopathogenic nematodes

    Directory of Open Access Journals (Sweden)

    Manana A. Lortkipanidze

    2016-06-01

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

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

    Science.gov (United States)

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

    2013-03-01

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

  2. At-Sea Associations in Foraging Little Penguins

    Science.gov (United States)

    Berlincourt, Maud; Arnould, John P. Y.

    2014-01-01

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

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

    Science.gov (United States)

    Pérez-Ortega, María; İsfendiyaroğlu, Süreyya

    2017-07-01

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

  4. At-sea associations in foraging little penguins.

    Directory of Open Access Journals (Sweden)

    Maud Berlincourt

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

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

    National Research Council Canada - National Science Library

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

    2014-01-01

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

  6. Urban foraging and the relational ecologies of belonging

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Stabentheiner, Anton; Kovac, Helmut

    2016-06-20

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

  8. Nitrogen fertilization effects on sorghum forage yield and quality

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    1999-01-01

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

  10. Black hole foraging: feedback drives feeding

    CERN Document Server

    Dehnen, Walter

    2013-01-01

    We suggest a new picture of supermassive black hole (SMBH) growth in galaxy centers. Momentum-driven feedback from an accreting hole gives significant orbital energy but little angular momentum to the surrounding gas. Once central accretion drops, the feedback weakens and swept-up gas falls back towards the SMBH on near-parabolic orbits. These intersect near the black hole with partially opposed specific angular momenta, causing further infall and ultimately the formation of a small-scale accretion disk. The feeding rates into the disk typically exceed Eddington by factors of a few, growing the hole on the Salpeter timescale and stimulating further feedback. Natural consequences of this picture include (i) the formation and maintenance of a roughly toroidal distribution of obscuring matter near the hole; (ii) random orientations of successive accretion disk episodes; (iii) the possibility of rapid SMBH growth; (iv) tidal disruption of stars and close binaries formed from infalling gas, resulting in visible fl...

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

    Directory of Open Access Journals (Sweden)

    Jie Zhang

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

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

    Science.gov (United States)

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

    2015-01-01

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

  13. Changes in Rumen Microbial Community Composition during Adaption to an In Vitro System and the Impact of Different Forages.

    Directory of Open Access Journals (Sweden)

    Melanie B Lengowski

    Full Text Available This study examined ruminal microbial community composition alterations during initial adaption to and following incubation in a rumen simulation system (Rusitec using grass or corn silage as substrates. Samples were collected from fermenter liquids at 0, 2, 4, 12, 24, and 48 h and from feed residues at 0, 24, and 48 h after initiation of incubation (period 1 and on day 13 (period 2. Microbial DNA was extracted and real-time qPCR was used to quantify differences in the abundance of protozoa, methanogens, total bacteria, Fibrobacter succinogenes, Ruminococcus albus, Ruminobacter amylophilus, Prevotella bryantii, Selenomonas ruminantium, and Clostridium aminophilum. We found that forage source and sampling time significantly influenced the ruminal microbial community. The gene copy numbers of most microbial species (except C. aminophilum decreased in period 1; however, adaption continued through period 2 for several species. The addition of fresh substrate in period 2 led to increasing copy numbers of all microbial species during the first 2-4 h in the fermenter liquid except protozoa, which showed a postprandial decrease. Corn silage enhanced the growth of R. amylophilus and F. succinogenes, and grass silage enhanced R. albus, P. bryantii, and C. aminophilum. No effect of forage source was detected on total bacteria, protozoa, S. ruminantium, or methanogens or on total gas production, although grass silage enhanced methane production. This study showed that the Rusitec provides a stable system after an adaption phase that should last longer than 48 h, and that the forage source influenced several microbial species.

  14. Tasco-Forage: I. Influence of a seaweed extract on antioxidant activity in tall fescue and in ruminants.

    Science.gov (United States)

    Fike, J H; Allen, V G; Schmidt, R E; Zhang, X; Fontenot, J P; Bagley, C P; Ivy, R L; Evans, R R; Coelho, R W; Wester, D B

    2001-04-01

    Seaweed (Ascophyllum nodosum) is a known source of plant growth regulators, and application to turfgrasses has increased activity of the antioxidant superoxide dismutase (SOD) and specific vitamin precursors. Increased antioxidant activity in both plants and animals diminishes oxidative stress. Two pasture experiments investigated effects of Tasco-Forage (a proprietary seaweed-based product) applied to tall fescue (Festuca arundinacea) on antioxidant activity in plants and in ruminants that grazed the forage. In Exp. 1, fescue was 70 to 100% infected with the endophyte fungus Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Twenty-four wether lambs (initial BW 41 kg; SD = 5) grazed fescue treated with 0, 1.7, or 3.4 kg Tasco/ha applied in April and July, 1994, with four replications per treatment. Grazing occurred for 26 d beginning April 21 and for 22 d beginning July 19. In July, there was a linear increase in daily gains (P Prairie, MS, where 1/4 Brahman x 3/4 Angus steers were used. Forty-eight steers were included at each location in each year (n = 192 total steers for 1996 and 1997). Steers that grazed infected tall fescue in Mississippi had lower (P antioxidant activity in grazing steers, whereas Tasco seemed to increase antioxidant activity in both the forage and the grazing ruminant. Tasco may provide opportunities to reduce oxidative stress in plants and animals.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    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.

  17. BLACK HOLE FORAGING: FEEDBACK DRIVES FEEDING

    Energy Technology Data Exchange (ETDEWEB)

    Dehnen, Walter; King, Andrew, E-mail: wd11@leicester.ac.uk, E-mail: ark@astro.le.ac.uk [Theoretical Astrophysics Group, University of Leicester, Leicester LE1 7RH (United Kingdom)

    2013-11-10

    We suggest a new picture of supermassive black hole (SMBH) growth in galaxy centers. Momentum-driven feedback from an accreting hole gives significant orbital energy, but little angular momentum to the surrounding gas. Once central accretion drops, the feedback weakens and swept-up gas falls back toward the SMBH on near-parabolic orbits. These intersect near the black hole with partially opposed specific angular momenta, causing further infall and ultimately the formation of a small-scale accretion disk. The feeding rates into the disk typically exceed Eddington by factors of a few, growing the hole on the Salpeter timescale and stimulating further feedback. Natural consequences of this picture include (1) the formation and maintenance of a roughly toroidal distribution of obscuring matter near the hole; (2) random orientations of successive accretion disk episodes; (3) the possibility of rapid SMBH growth; (4) tidal disruption of stars and close binaries formed from infalling gas, resulting in visible flares and ejection of hypervelocity stars; (5) super-solar abundances of the matter accreting on to the SMBH; and (6) a lower central dark-matter density, and hence annihilation signal, than adiabatic SMBH growth implies. We also suggest a simple subgrid recipe for implementing this process in numerical simulations.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

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

    2013-08-15

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

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

    Directory of Open Access Journals (Sweden)

    Matthieu Authier

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

  1. Phenology and cover of plant growth forms predict herbivore habitat selection in a high latitude ecosystem.

    Science.gov (United States)

    Iversen, Marianne; Fauchald, Per; Langeland, Knut; Ims, Rolf A; Yoccoz, Nigel G; Bråthen, Kari Anne

    2014-01-01

    The spatial and temporal distribution of forage quality is among the most central factors affecting herbivore habitat selection. Yet, for high latitude areas, forage quantity has been found to be more important than quality. Studies on large ungulate foraging patterns are faced with methodological challenges in both assessing animal movements at the scale of forage distribution, and in assessing forage quality with relevant metrics. Here we use first-passage time analyses to assess how reindeer movements relate to forage quality and quantity measured as the phenology and cover of growth forms along reindeer tracks. The study was conducted in a high latitude ecosystem dominated by low-palatable growth forms. We found that the scale of reindeer movement was season dependent, with more extensive area use as the summer season advanced. Small-scale movement in the early season was related to selection for younger stages of phenology and for higher abundances of generally phenologically advanced palatable growth forms (grasses and deciduous shrubs). Also there was a clear selection for later phenological stages of the most dominant, yet generally phenologically slow and low-palatable growth form (evergreen shrubs). As the summer season advanced only quantity was important, with selection for higher quantities of one palatable growth form and avoidance of a low palatable growth form. We conclude that both forage quality and quantity are significant predictors to habitat selection by a large herbivore at high latitude. The early season selectivity reflected that among dominating low palatability growth forms there were palatable phenological stages and palatable growth forms available, causing herbivores to be selective in their habitat use. The diminishing selectivity and the increasing scale of movement as the season developed suggest a response by reindeer to homogenized forage availability of low quality.

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

    Science.gov (United States)

    Doblas-Miranda, Enrique; Reyes-López, Joaquín

    2008-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Maximilian Drakeley

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

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

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

    2011-03-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Tan, Ken; Hu, Zongwen; Chen, Weiwen; Wang, Zhengwei; Wang, Yuchong; Nieh, James C

    2013-01-01

    Fear can have strong ecosystem effects by giving predators a role disproportionate to their actual kill rates. In bees, fear is shown through foragers avoiding dangerous food sites, thereby reducing the fitness of pollinated plants. However, it remains unclear how fear affects pollinators in a complex natural scenario involving multiple predator species and different patch qualities. We studied hornets, Vespa velutina (smaller) and V. tropica (bigger) preying upon the Asian honey bee, Apis cerana in China. Hornets hunted bees on flowers and were attacked by bee colonies. Bees treated the bigger hornet species (which is 4 fold more massive) as more dangerous. It received 4.5 fold more attackers than the smaller hornet species. We tested bee responses to a three-feeder array with different hornet species and varying resource qualities. When all feeders offered 30% sucrose solution (w/w), colony foraging allocation, individual visits, and individual patch residence times were reduced according to the degree of danger. Predator presence reduced foraging visits by 55-79% and residence times by 17-33%. When feeders offered different reward levels (15%, 30%, or 45% sucrose), colony and individual foraging favored higher sugar concentrations. However, when balancing food quality against multiple threats (sweeter food corresponding to higher danger), colonies exhibited greater fear than individuals. Colonies decreased foraging at low and high danger patches. Individuals exhibited less fear and only decreased visits to the high danger patch. Contrasting individual with emergent colony-level effects of fear can thus illuminate how predators shape pollination by social bees.

  11. Estimation of indigestible NDF in forages and concentrates from cell wall composition

    DEFF Research Database (Denmark)

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

    2012-01-01

    This study examined the potential of plant cell wall fractions as predictors of indigestible neutral detergent fibre (INDF) in forages with respect to species within plant type, cut number and stage of maturity (harvest time) within primary growth, and for concentrates with respect to species...... within plant type, where INDF is defined as the portion of plant cell walls not digested after 288 h rumen incubation in Dacron bags with 12 μm pore size. INDF is one of the more important parameters determining the net energy (NE) value of a diet in some recently developed ruminant feed evaluation...... to develop regression equations for INDF intended for use in practice based on a total of 321 samples. Plant type and species within plant type affected (Pcell wall fractions. The INDF/lignin(sa) ratio varied substantially from the 2.4 factor used in the Cornell Net Carbohydrate and Protein...

  12. A foraging cost of migration for a partially migratory cyprinid fish

    DEFF Research Database (Denmark)

    Chapman, Ben B; Eriksen, Anders; Baktoft, Henrik

    2013-01-01

    Rutilus rutilus, which migrates from shallow lakes to streams during winter. By sampling fish from stream and lake habitats in the autumn and spring and measuring their stomach fullness and diet composition, we tested if migrating roach pay a cost of reduced foraging when migrating. Resident fish had......Migration has evolved as a strategy to maximise individual fitness in response to seasonally changing ecological and environmental conditions. However, migration can also incur costs, and quantifying these costs can provide important clues to the ultimate ecological forces that underpin migratory...... behaviour. A key emerging model to explain migration in many systems posits that migration is driven by seasonal changes to a predation/growth potential (p/g) trade-off that a wide range of animals face. In this study we assess a key assumption of this model for a common cyprinid partial migrant, the roach...

  13. Influence of management regime and harvest date on the forage quality of rangelands plants: the importance of dry matter content.

    Science.gov (United States)

    Bumb, Iris; Garnier, Eric; Bastianelli, Denis; Richarte, Jean; Bonnal, Laurent; Kazakou, Elena

    2016-01-01

    In spite of their recognized ecological value, relatively little is known about the nutritional value of species-rich rangelands for herbivores. We investigated the sources of variation in dry matter digestibility (DMD), neutral detergent fibre content (NDF) and nitrogen concentration (NC) in plants from species-rich Mediterranean rangelands in southern France, and tested whether the dry matter content (DMC) was a good predictor of the forage quality of different plant parts. Sixteen plant species with contrasting growth forms (rosette, tussock, extensive and stemmed-herb) were studied, representative of two management regimes imposed in these rangelands: (i) fertilization and intensive grazing and (ii) non-fertilization and moderate grazing. Among the 16 plant species, four species were found in both treatments, allowing us to assess the intraspecific variability in forage quality and DMC across the treatments. The components of nutritional value (DMD, NDF and NC) as well as the DMC of leaves, stems and reproductive plant parts, were assessed at the beginning of the growing season and at peak standing biomass. All components of nutritional value and DMC were affected by species growth form: rosettes had higher DMD and NC than tussocks; the reverse being found for NDF and DMC. As the season progressed, DMD and NC of the different plant parts decreased while NDF and DMC increased for all species. DMC was negatively related to DMD and NC and positively to NDF, regardless of the source of variation (species, harvest date, management regime or plant part). Path analysis indicated that NDF was the main determinant of DMD. Better assessment of forage quality in species-rich systems requires consideration of their growth form composition. DMC of all plant parts, which is closely related to NDF, emerged as a good predictor and easily measured trait to estimate DMD in these species-rich systems. Published by Oxford University Press on behalf of the Annals of Botany Company.

  14. Relationship of red and photographic infrared spectral radiances to alfalfa biomass, forage water content, percentage canopy cover, and severity of drought stress

    Science.gov (United States)

    Tucker, C. J.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

    1979-01-01

    Red and photographic infrared spectral data were collected using a handheld radiometer for two cuttings of alfalfa. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover for the earlier alfalfa cutting. The alfalfa of later cutting experienced a period of severe drought stress which limited growth. The spectral variables were found to be highly correlated with the estimated drought scores for this alfalfa cutting.

  15. Division of foraging labor in the bumble bee, Bombus impatiens : effect of removing pollen specialists and colony adoption

    OpenAIRE

    Hagbery, Jessica

    2011-01-01

    Foraging specialization plays an important role in the ability of social Hymenoptera to efficiently allocate labor and adapt to environmental changes. However, relatively little is known about whether bumble bees, important social pollinators, can flexibly allocate their foraging. I removed pollen specialists at different stages in the life of a Bombus impatiens colony and recorded the pollen and nectar foraging of every forager on each foraging trip over the lifetimes of five established col...

  16. 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.

  17. Forage as a primary source of mycotoxins in animal diets.

    Science.gov (United States)

    Skládanka, Jiří; Nedělník, Jan; Adam, Vojtěch; Doležal, Petr; Moravcová, Hana; Dohnal, Vlastimil

    2011-01-01

    The issue of moulds and, thus, contamination with mycotoxins is very topical, particularly in connexion with forages from grass stands used at the end of the growing season. Deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUM) and aflatoxins (AFL) are among the most common mycotoxins. The aim of the paper was to determine concentrations of mycotoxins in selected grasses (Lolium perenne, Festulolium pabulare, Festulolium braunii) and their mixtures with Festuca rubra an/or Poa pratensis during the growing season as a marker of grass safety, which was assessed according to content of the aforementioned mycotoxins. During the growing season grass forage was contaminated with mycotoxins, most of all by DON and ZEA. The contents of AFL and FUM were zero or below the limit of quantification. Moreover, the level of the occurrence of mould was quantified as ergosterol content, which was higher at the specific date of cut. All results were statistically processed and significant changes were discussed.

  18. Do bigger bats need more time to forage?

    Directory of Open Access Journals (Sweden)

    CEL. Esbérard

    Full Text Available We test the hypothesis is that bats using the same area and at the same time would be using similar preys, but they would have different foraging times due to specific differences in biomass. A total of 730 captures was analyzed 13 species of Vespertilionidae and Molossidae bats netted over a small dam in southeastern Brazil from 1993 and 1999. The relationship between the average time of captures and the biomass of the species of Vespertilinidae and Molossidae most frequent (captures > 4 was positive and significant (r = 0.83, p = 0.022, N = 7. Two lines are discussed to answer the longer foraging time for bigger bats: 1 larger insectivorous bats don't consume proportionally larger preys and 2 larger insects are less available.

  19. PCNN document segmentation method based on bacterial foraging optimization algorithm

    Science.gov (United States)

    Liao, Yanping; Zhang, Peng; Guo, Qiang; Wan, Jian

    2014-04-01

    Pulse Coupled Neural Network(PCNN) is widely used in the field of image processing, but it is a difficult task to define the relative parameters properly in the research of the applications of PCNN. So far the determination of parameters of its model needs a lot of experiments. To deal with the above problem, a document segmentation based on the improved PCNN is proposed. It uses the maximum entropy function as the fitness function of bacterial foraging optimization algorithm, adopts bacterial foraging optimization algorithm to search the optimal parameters, and eliminates the trouble of manually set the experiment parameters. Experimental results show that the proposed algorithm can effectively complete document segmentation. And result of the segmentation is better than the contrast algorithms.

  20. Evolution of sustained foraging in 3D environments with physics

    CERN Document Server

    Chaumont, Nicolas

    2011-01-01

    Artificially evolving foraging behavior in simulated legged animals has proved to be a notoriously difficult task. Here, we co-evolve the morphology and controller for virtual organisms in a three-dimensional physically realistic environment to produce goal-directed legged locomotion. We show that following and reaching multiple food sources can evolve de novo, by evaluating each organism on multiple food sources placed on a basic pattern that is gradually randomized across generations. We devised a strategy of evolutionary "staging", where the best organism from a set of evolutionary experiments using a particular fitness function is used to seed a new set, with a fitness function that is progressively altered to better challenge organisms as evolution improves them. We find that an organism's efficiency at reaching the first food source does not predict its ability at finding subsequent ones because foraging efficiency crucially depends on the position of the last food source reached, an effect illustrated ...

  1. Linking animal population dynamics to alterations in foraging behaviour

    DEFF Research Database (Denmark)

    Nabe-Nielsen, Jacob; Sibly, Richard; Tougaard, Jakob

    Background/Question/Methods The survival of animal populations is strongly influenced by the individuals’ ability to forage efficiently, yet there are few studies of how populations respond when disturbances cause animals to deviate from their natural foraging behavior. Animals that respond...... was not jeopardized even when disturbances were simulated to have a relatively large and persistent effect on the behavior of individual animals. Porpoises were simulated to move away from noisy objects, preventing them from returning to the known food patches in that area. This resulted in decreasing energy reserves...... that are increasingly exposed to noise from ships, wind turbines, etc. In the present study we investigate how the dynamics of the harbor porpoise population (Phocoena phocoena) in the inner Danish waters is influenced by disturbances using an agent- based simulation model. In the model animal movement, and hence...

  2. Extrafloral nectar content alters foraging preferences of a predatory ant.

    Science.gov (United States)

    Wilder, Shawn M; Eubanks, Micky D

    2010-04-23

    We tested whether the carbohydrate and amino acid content of extrafloral nectar affected prey choice by a predatory ant. Fire ants, Solenopsis invicta, were provided with artificial nectar that varied in the presence of carbohydrates and amino acids and were then provided with two prey items that differed in nutritional content, female and male crickets. Colonies of fire ants provided with carbohydrate supplements consumed less of the female crickets and frequently did not consume the high-lipid ovaries of female crickets. Colonies of fire ants provided with amino acid supplements consumed less of the male crickets. While a number of studies have shown that the presence of extrafloral nectar or honeydew can affect ant foraging activity, these results suggest that the nutritional composition of extrafloral nectar is also important and can affect subsequent prey choice by predatory ants. Our results suggest that, by altering the composition of extrafloral nectar, plants could manipulate the prey preferences of ants foraging on them.

  3. A mathematical and experimental study of ant foraging trail dynamics.

    Science.gov (United States)

    Johnson, Katie; Rossi, Louis F

    2006-07-21

    In this article, we present a mathematical model coupled to an experimental study of ant foraging trails. Our laboratory experiments on Tetramorium caespitum do not find a strong relationship between ant densities and velocities, a common assumption in traffic modeling. Rather, we find that higher order effects play a major role in observed behavior, and our model reflects this by including inertial terms in the evolution equation. A linearization of the resulting system yields left- and right-moving waves, in agreement with laboratory measurements. The linearized system depends upon Froude numbers reflecting a ratio of the energy stored in the foraging trail to the kinetic energy of the ants. The model predicts and the measurements support the existence of two distinct phase velocities.

  4. Protecting rain forests and forager's rights using LANDSAT imagery

    Science.gov (United States)

    Wilkie, David S.

    1991-01-01

    Creating rain forest reserves is vital given the global decline in biodiversity. Yet, the plants and animals that will be protected from untrammeled commercial exploitation within such reserves constitute essential resources for indigenous foragers and farmers. Balancing the needs of local subsistence level populations with the goals of national and international conservation agencies requires a thorough understanding of the mutual impacts that arise from the interaction of park and people. In the Ituri forest of Zaire, LANDSAT TM image analysis and GPS ground truth data were used to locate human settlements so that boundaries of the proposed Okapi Reserve could be chosen to minimize its impact on the subsistence practices of the local foragers and farmers. Using satellite imagery in conjunction with cultural information should help to ensure traditional resource exploitation rights of indigenous peoples whilst simultaneously protecting the largest contiguous area of undisturbed forest.

  5. Protecting rain forests and forager's rights using LANDSAT imagery

    Science.gov (United States)

    Wilkie, David S.

    1991-01-01

    Creating rain forest reserves is vital given the global decline in biodiversity. Yet, the plants and animals that will be protected from untrammeled commercial exploitation within such reserves constitute essential resources for indigenous foragers and farmers. Balancing the needs of local subsistence level populations with the goals of national and international conservation agencies requires a thorough understanding of the mutual impacts that arise from the interaction of park and people. In the Ituri forest of Zaire, LANDSAT TM image analysis and GPS ground truth data were used to locate human settlements so that boundaries of the proposed Okapi Reserve could be chosen to minimize its impact on the subsistence practices of the local foragers and farmers. Using satellite imagery in conjunction with cultural information should help to ensure traditional resource exploitation rights of indigenous peoples whilst simultaneously protecting the largest contiguous area of undisturbed forest.

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

    DEFF Research Database (Denmark)

    Ahrenfeldt, Erica Juel

    Denmark and under widespread cultivation in the rest of the world. A review study (IV) of the literature on wild bees and their pollination services in flowering crops make up the final part of the thesis. The review study aimed to assess how wild bees may respond to landscape parameters based......The agricultural value of wild bees is their contribution to crop pollination and studies have shown that abundance, species richness and functional diversity of bees can increase yield and quality of flowering crops. Wild bee pollination services thus carry great value regardless of the presence...... to a landscape with fragmented resources may already have taken place in the areas sampled. Paper I and III showed that limitations on foraging ability and different foraging needs can drive different visitation patterns in a flowering crop. The review study (IV) found variation in results from different studies...

  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. 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.

  9. Artificial Plant Root System Growth for Distributed Optimization: Models and Emergent Behaviors

    Directory of Open Access Journals (Sweden)

    Su Weixing

    2016-01-01

    Full Text Available Plant root foraging exhibits complex behaviors analogous to those of animals, including the adaptability to continuous changes in soil environments. In this work, we adapt the optimality principles in the study of plant root foraging behavior to create one possible bio-inspired optimization framework for solving complex engineering problems. This provides us with novel models of plant root foraging behavior and with new methods for global optimization. This framework is instantiated as a new search paradigm, which combines the root tip growth, branching, random walk, and death. We perform a comprehensive simulation to demonstrate that the proposed model accurately reflects the characteristics of natural plant root systems. In order to be able to climb the noise-filled gradients of nutrients in soil, the foraging behaviors of root systems are social and cooperative, and analogous to animal foraging behaviors.

  10. Forage yield and growth of “Panicum maximum” cvs. Mombaça and Tanzania-1 and Mulato hybrid Brachiaria under phosphorus application Teores críticos de fósforo no solo e características morfogênicas de "Panicum maximum" cultivares Mombaça e Tanzânia-1 e Brachiaria híbrida Mulato sob aplicação de fósforo

    Directory of Open Access Journals (Sweden)

    Felipe Schneider

    2010-06-01

    Full Text Available The experiment was carried out in west of Paraná state, in Red Eutroferric Latosoil. The objective was to verify, in the establishment, the available P concentration in soil and critical doses of P to yield of dry matter (DM and tillering and, in the 2° year, the growth of Panicum maximum cvs. Mombaça and Tanzânia-1 and Brachiaria sp. hibrid Mulato. The treatments were three forages and five P2O5 rates (0, 40, 80, 120 e 240 kg/ha randomized in three complete blocks in factorial arrange. The phosphorus rates linearly increased the P available in soil extracted by Mehlich-1 method (ŷ =-4,5136 + 1,0241X, R2=0,96, ŷ, in mg/dm3. The P application increased, up to maximum, the DM yield of forages Mombaça (ŷ=6.472 + 74,41X – 0,241X2 R2=0,97, Tanzânia-1 (ŷ =6.923 + 70,95X – 0,249X2, R2=0,88 and Mulato (ŷ =7.393 + 94,42X – 0,341X2, R2=0,72 and the tiller density (TD. The critical phosphorus rates of 54, 44 e 48kg/ha of P2O5, respectively, to Mombaça, Tanzânia-1 and Mulato and P critical concentrations in soil of 51, 41 and 44mg/dm3. In the establishment, the mulato-grass presented highers DM yield and TD (11.169kg/ha and 69 tillers/0,25m2. The DM yield and TD in the mombaça-grass (9.787kg/ha and 54 perfilhos/0,25m2 and the tanzania-grass (9.563kg/ha and 52 perfilhos/0,25m2 were equal. In the 2° year, there were no variations in DM yield. The highest leaf elogantion ratio (LER and leaf appearance ratio (LAR were obtained in mombaça-grass and mulato-grass, respectively. The mulato-grass presented lower phylocron.O experimento foi conduzido na região Oeste do Paraná, em Latossolo Vermelho Eutroférrico de textura argilosa. O objetivo foi determinar, no estabelecimento, os teores críticos de P disponível e as doses críticas para produção de matéria seca (PMS e perfilhamento e, no 2° ano, o crescimento de Panicum maximum cvs. Mombaça e Tanzânia-1 e Brachiaria sp. híbrida Mulato. Os tratamentos foram: três forrageiras e cinco

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

    Science.gov (United States)

    Hall, M B; Chase, L E

    2014-05-01

    In response to drought-induced forage shortages along with increased corn and soy prices, this study was conducted to evaluate lactation responses of dairy cows to lower-forage diets supplemented with forage substitutes. By-product feeds were used to completely replace corn grain and soybean feeds. Forty-eight late-lactation cows were assigned to 1 of 4 diets using a randomized complete block design with a 2-wk covariate period followed by a 4-wk experimental period. The covariate diet contained corn grain, soybean meal, and 61% forage. Experimental diets contained chopped wheat straw (WS)/sugar beet pulp at 0/12, 3/9, 6/6, or 9/3 percentages of diet dry matter (DM). Corn silage (20%), alfalfa silage (20%), pelleted corn gluten feed (25.5%), distillers grains (8%), whole cottonseed (5%), cane molasses/whey blend (7%), and vitamin and mineral mix with monensin (2.5%) comprised the rest of diet DM. The WS/sugar beet pulp diets averaged 16.5% crude protein, 35% neutral detergent fiber, and 11% starch (DM basis). Cows consuming the experimental diets maintained a 3.5% fat- and protein-corrected milk production (35.2 kg; standard deviation=5.6 kg) that was numerically similar to that measured in the covariate period (35.3 kg; standard deviation=5.0 kg). Intakes of DM and crude protein declined linearly as WS increased, whereas neutral detergent fiber intake increased linearly. Linear increases in time spent ruminating (from 409 to 502 min/d) and eating (from 156 to 223 min/d) were noted as WS inclusion increased. Yields of milk fat and 3.5% fat-and protein-corrected milk did not change as WS increased, but those of protein and lactose declined linearly. Phosphorous intakes were in excess of recommended levels and decreased linearly with increasing WS inclusion. Nutritional model predictions for multiparous cows were closest to actual performance for the National Research Council 2001 model when a metabolizable protein basis was used; primiparous cow performance was

  12. Effects of forage type, forage to concentrate ratio, and crushed linseed supplementation on milk fatty acid profile in lactating dairy cows

    NARCIS (Netherlands)

    Sterk, A.R.; Johansson, B.E.O.; Taweel, H.Z.H.; Murphy, M.; Vuuren, van A.M.; Hendriks, W.H.; Dijkstra, J.

    2011-01-01

    The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. S

  13. Low forager fertility: demographic characteristic or methodological artifact?

    Science.gov (United States)

    Early, J D

    1985-09-01

    Anthropological literature has long held that traditional foraging populations have low fertility levels. This research examines the number of live births per woman for 9 non-western forager groups who have been investigated in the last 20 years. Data are derived from 1) birth registration systems, 2) surveys conducted during short stays with the group, and 3) surveys conducted as part of longer ethnographic studies. Fertility rates for the groups are 1) 3.5 for the Kiunga area of Papula, New Guinea, 2) 4.2 for Northern Territory Australian aborigines, 3) 5.0 for Cayapo groups in Brazil, 4) 5.3 for Hiowe people of New Guinea, 5) 5.7 for 3 Xavante groups in Brazil, 6) 6.0 for West Alaskan Eskimos, 7) 6.9 for Nunamiut Eskimos of Alaska, 8) 7.6 for the Bisman-Asmat group of Indonesian New Guinea, and 9) 8.4 for the Winikina Warao of Venezuela. Since fertility rates are highest when ethnographic studies, which allow for question clarification, memory recall, and cross-checking, are used, the author believes that high fertility rates most accurately represent forager societies. Research on the Dobe ]Kung (fertility rate - 4.7), may contradict these findings, but the author believes that the ]Kung fertility rates are higher than reported because of infanticide practices, sexual abstinence during lactation, and disease related fertility problems. In summary, the study finds high fertility (7-9 births) in traditional foraging societies. Although the study examines small populations, correlation strength and overall consistency help verify the results.

  14. Potential of Caatinga forage plants in ruminant feeding

    OpenAIRE

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

    2010-01-01

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

  15. Fine-scale variability in harbor seal foraging behavior.

    Directory of Open Access Journals (Sweden)

    Kenady Wilson

    Full Text Available Understanding the variability of foraging behavior within a population of predators is important for determining their role in the ecosystem and how they may respond to future ecosystem changes. However, such variability has seldom been studied in harbor seals on a fine spatial scale (<30 km. We used a combination of standard and Bayesian generalized linear mixed models to explore how environmental variables influenced the dive behavior of harbor seals. Time-depth recorders were deployed on harbor seals from two haul-out sites in the Salish Sea in 2007 (n = 18 and 2008 (n = 11. Three behavioral bout types were classified from six dive types within each bout; however, one of these bout types was related to haul-out activity and was excluded from analyses. Deep foraging bouts (Type I were the predominant type used throughout the study; however, variation in the use of bout types was observed relative to haul-out site, season, sex, and light (day/night. The proportional use of Type I and Type II (shallow foraging/traveling bouts differed dramatically between haul-out sites, seasons, sexes, and whether it was day or night; individual variability between seals also contributed to the observed differences. We hypothesize that this variation in dive behavior was related to habitat or prey specialization by seals from different haul-out sites, or individual variability between seals in the study area. The results highlight the potential influence of habitat and specialization on the foraging behavior of harbor seals, and may help explain the variability in diet that is observed between different haul-out site groups in this population.

  16. 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.

  17. Intersexual and temporal variation in foraging ecology of prothonotary warblers during the breeding season

    Science.gov (United States)

    Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J.

    1990-01-01

    We studied foraging ecology of Prothonotary Warblers (Protonotaria citrea) over four breeding seasons to determine if this species exhibited sex-specific or temporal variation in foraging behavior. Significant differences between sexes during the prenestling period were found for foraging height and substrate height (foraging method, plant species/substrate, perch diameter, horizontal location from trunk, and prey location were not significantly different). During the nestling period, this divergence between sexes was evident for foraging height, substrate height, substrate / tree species, and prey location. Additionally, male warblers significantly altered their behavior for all seven foraging variables between the two periods, whereas females exhibited changes similar to those of males for five of the foraging variables. This parallel shift suggests a strong behavioral response by both sexes to proximate factors (such as vegetation structure, and prey abundance and distribution) that varied throughout the breeding season. Sex-specific foraging behavior during the prenestling period was best explained by differences in reproductive responsibilities rather than by the theory of intersexual competition for limited resources. During the nestling period, neither hypothesis by itself explained foraging divergences adequately. However, when integrated with the temporal responses of the warblers to changes in prey availability, reproductive responsibilities seemed to be of primary importance in explaining intersexual niche partitioning during the nestling period. We emphasize the importance of considering both intersexual and intraseasonal variation when quantifying a species' foraging ecology.

  18. How phylogeny and foraging ecology drive the level of chemosensory exploration in lizards and snakes.

    Science.gov (United States)

    Baeckens, S; Van Damme, R; Cooper, W E

    2017-03-01

    The chemical senses are crucial for squamates (lizards and snakes). The extent to which squamates utilize their chemosensory system, however, varies greatly among taxa and species' foraging strategies, and played an influential role in squamate evolution. In lizards, 'Scleroglossa' evolved a state where species use chemical cues to search for food (active foragers), whereas 'Iguania' retained the use of vision to hunt prey (ambush foragers). However, such strict dichotomy is flawed as shifts in foraging modes have occurred in all clades. Here, we attempted to disentangle effects of foraging ecology from phylogenetic trait conservatism as leading cause of the disparity in chemosensory investment among squamates. To do so, we used species' tongue-flick rate (TFR) in the absence of ecological relevant chemical stimuli as a proxy for its fundamental level of chemosensory investigation, that is baseline TFR. Based on literature data of nearly 100 species and using phylogenetic comparative methods, we tested whether and how foraging mode and diet affect baseline TFR. Our results show that baseline TFR is higher in active than ambush foragers. Although baseline TFRs appear phylogenetically stable in some lizard taxa, that is a consequence of concordant stability of foraging mode: when foraging mode shifts within taxa, so does baseline TFR. Also, baseline TFR is a good predictor of prey chemical discriminatory ability, as we established a strong positive relationship between baseline TFR and TFR in response to prey. Baseline TFR is unrelated to diet. Essentially, foraging mode, not phylogenetic relatedness, drives convergent evolution of similar levels of squamate chemosensory investigation.

  19. Effects of predator chemical cues and behavioral biorhythms on foraging activity of terrestrial salamanders.

    Science.gov (United States)

    Maerz, J C; Panebianco, N L; Madison, D M

    2001-07-01

    Red-backed salamanders, Plethodon cinereus, show a variety of alarm responses to chemical cues from eastern garter snakes, Thamnophis sirtalis. We measured the foraging activity of red-backed salamanders exposed to water soiled by a garter snake (fed P. cinereus) or to unsoiled water. Salamanders exposed to snake-soiled water showed less foraging activity than salamanders exposed to unsoiled water; therefore, predators could have nonlethal effects on salamander populations. Our results also show additional factors influenced salamander foraging activity. Salamander foraging activity and responsiveness to chemical cues do not appear to have been affected by sex or food deprivation. Salamander foraging activity does appear to have been influenced by activity biorhythms. Foraging activity of animals in both treatments showed a bimodal periodicity that is consistent with natural activity patterns controlled by internal biorhythms. Exposure to snake-soiled water significantly reduced foraging activity during periods of peak foraging activity, but had a subtler effect on foraging activity during natural lulls in activity. We suggest that both activity biorhythms and exposure to chemical cues are important factors affecting salamander foraging behavior.

  20. 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.

  1. 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.

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

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    Jennifer W. MacAdam

    2015-07-01

    Full Text Available The two temperate forage legumes containing condensed tannins (CT that promote ruminant production are birdsfoot trefoil (Lotus corniculatus L.; BFT and sainfoin (Onobrychis viciifolia Scop.; SF. Both are well-adapted to the cool-temperate climate and alkaline soils of the Mountain West USA. Condensed tannins comprise a diverse family of bioactive chemicals with multiple beneficial functions for ruminants, including suppression of internal parasites and enteric methane. Birdsfoot trefoil contains 10 to 40 g·CT·kg−1 dry matter (DM, while SF contains 30 to 80 g·CT·kg−1 DM. Our studies have focused on these two plant species and have demonstrated consistently elevated rates of gain for beef calves grazing both BFT and SF. Novel results from our BFT research include carcass dressing percentages and consumer sensory evaluations equivalent to feedlot-finished steers and significantly greater than grass-finished steers, but with omega-3 fatty acid concentrations equal to grass-finished beef. We have further demonstrated that ruminants fed BFT or SF will consume more endophyte-infected tall fescue (Schedonorus arundinaceus (Schreb. Dumort. forage or seed than ruminants fed a non-CT forage legume. There is great potential value for sustainable livestock production in the use of highly digestible, nitrogen-fixing legumes containing tannins demonstrated to improve ruminant productivity.

  3. 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.

  4. 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.

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

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    Demment Montague W

    2009-04-01

    Full Text Available Abstract Background Understanding the mechanisms that influence grazing selectivity in patchy environments is vital to promote sustainable production and conservation of cultivated and natural grasslands. To better understand how patch size and spatial dynamics influence selectivity in cattle, we examined grazing selectivity under 9 different treatments by offering alfalfa and fescue in patches of 3 sizes spaced with 1, 4, and 8 m between patches along an alley. We hypothesized that (1 selectivity is driven by preference for the forage species that maximizes forage intake over feeding scales ranging from single bites to patches along grazing paths, (2 that increasing patch size enhances selectivity for the preferred species, and that (3 increasing distances between patches restricts selectivity because of the aggregation of scale-specific behaviours across foraging scales. Results Cows preferred and selected alfalfa, the species that yielded greater short-term intake rates (P Conclusion We conclude that patch size and spacing affect components of intake rate and, to a lesser extent, the selectivity of livestock at lower hierarchies of the grazing process, particularly by enticing livestock to make more even use of the available species as patches are spaced further apart. Thus, modifications in the spatial pattern of plant patches along with reductions in the temporal and spatial allocation of grazing may offer opportunities to improve uniformity of grazing by livestock and help sustain biodiversity and stability of plant communities.

  6. Evidence for acoustic communication among bottom foraging humpback whales.

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    Parks, Susan E; Cusano, Dana A; Stimpert, Alison K; Weinrich, Mason T; Friedlaender, Ari S; Wiley, David N

    2014-12-16

    Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a 'paired burst' sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species.

  7. Co-evolution of learning complexity and social foraging strategies.

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    Arbilly, Michal; Motro, Uzi; Feldman, Marcus W; Lotem, Arnon

    2010-12-21

    Variation in learning abilities within populations suggests that complex learning may not necessarily be more adaptive than simple learning. Yet, the high cost of complex learning cannot fully explain this variation without some understanding of why complex learning is too costly for some individuals but not for others. Here we propose that different social foraging strategies can favor different learning strategies (that learn the environment with high or low resolution), thereby maintaining variable learning abilities within populations. Using a genetic algorithm in an agent-based evolutionary simulation of a social foraging game (the producer-scrounger game) we demonstrate how an association evolves between a strategy based on independent search for food (playing a producer) and a complex (high resolution) learning rule, while a strategy that combines independent search and following others (playing a scrounger) evolves an association with a simple (low resolution) learning rule. The reason for these associations is that for complex learning to have an advantage, a large number of learning steps, normally not achieved by scroungers, are necessary. These results offer a general explanation for persistent variation in cognitive abilities that is based on co-evolution of learning rules and social foraging strategies.

  8. Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi

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    Narendra, Ajay; Gourmaud, Sarah; Zeil, Jochen

    2013-01-01

    Ants are efficient navigators, guided by path integration and visual landmarks. Path integration is the primary strategy in landmark-poor habitats, but landmarks are readily used when available. The landmark panorama provides reliable information about heading direction, routes and specific location. Visual memories for guidance are often acquired along routes or near to significant places. Over what area can such locally acquired memories provide information for reaching a place? This question is unusually approachable in the solitary foraging Australian jack jumper ant, since individual foragers typically travel to one or two nest-specific foraging trees. We find that within 10 m from the nest, ants both with and without home vector information available from path integration return directly to the nest from all compass directions, after briefly scanning the panorama. By reconstructing panoramic views within the successful homing range, we show that in the open woodland habitat of these ants, snapshot memories acquired close to the nest provide sufficient navigational information to determine nest-directed heading direction over a surprisingly large area, including areas that animals may have not visited previously. PMID:23804615

  9. Therapeutic Potential of Temperate Forage Legumes: A Review.

    Science.gov (United States)

    Cornara, Laura; Xiao, Jianbo; Burlando, Bruno

    2016-07-29

    The discovery of bioactive molecules from botanical sources is an expanding field, preferentially oriented to plants having a tradition of use in medicine and providing high yields and availability. Temperate forage legumes are Fabaceae species that include worldwide-important crops. These plants possess therapeutic virtues that have not only been used in veterinary and folk medicine, but have also attracted the interest of official medicine. We have examined here Medicago sativa (alfalfa), Trifolium pratense and T. repens (clovers), Melilotus albus and M. officinalis (sweet clovers), Lotus corniculatus (birdsfoot trefoil), Onobrychis viciifolia (sainfoin), Lespedeza capitata (roundhead lespedeza), and Galega officinalis (goat's rue). The phytochemical complexes of these species contain secondary metabolites whose pharmacological potentials deserve investigation. Major classes of compounds include alkaloids and amines, cyanogenic glycosides, flavonoids, coumarins, condensed tannins, and saponins. Some of these phytochemicals have been related to antihypercholesterolemia, antidiabetic, antimenopause, anti-inflammatory, antiedema, anthelmintic, and kidney protective effects. Two widely prescribed drugs have been developed starting from temperate forage legumes, namely, the antithrombotic warfarin, inspired from sweet clover's coumarin, and the antidiabetic metformin, a derivative of sainfoin's guanidine. Available evidence suggests that temperate forage legumes are a potentially important resource for the extraction of active principles to be used as nutraceuticals and pharmaceuticals.

  10. 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.

  11. New Inoculants Containing Lactic Bacteria Applied in Forage Ensiling

    Directory of Open Access Journals (Sweden)

    Teodor Vintila

    2010-05-01

    Full Text Available In a first study, the capacity of lactic bacteria to accumulate biomass in different culture media and temperatures was tested and the biosynthesis parameters were established. In the second study, the strains producing the highest quantity of biomass and determining the most rapid pH drop in culture medium were conditioned in solid supports. The obtained solid products containing lactic bacteria were used to inoculate different types of forages. Ensilage was carried out in laboratory silos made from O2-impermeable plastic flasks, vacuumed using a vacuum pump. The experiment was 2 x 2 factorial with two types of forage (alfalfa and sorghum, each of them inoculated and not inoculated with lactic bacteria. The evolution of lactic bacteria, pH value, and the concentration in volatile acids was verified. In the third experiment, lactic bacteria were used to inoculate silages in farm conditions. The obtained results recommend the tested strain for the improvement of preserving conditions and nutritive value in ensiled forages.

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

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    Sonny S. Bleicher

    2016-01-01

    Full Text Available In environments where food resources are spatially variable and temporarily impoverished, consumers that encounter habitat patches with different food density should focus their foraging initially where food density is highest before they move to patches where food density is lower. Increasing missed opportunity costs should drive individuals progressively to patches with lower food density as resources in the initially high food density patches deplete. To test these expectations, we assessed the foraging decisions of two species of dasyurid marsupials (dunnarts: Sminthopsis hirtipes and S. youngsoni during a deep drought, or bust period, in the Simpson Desert of central Australia. Dunnarts were allowed access to three patches containing different food densities using an interview chamber experiment. Both species exhibited clear preference for the high density over the lower food density patches as measured in total harvested resources. Similarly, when measuring the proportion of resources harvested within the patches, we observed a marginal preference for patches with initially high densities. Models analyzing behavioral choices at the population level found no differences in behavior between the two species, but models analyzing choices at the individual level uncovered some variation. We conclude that dunnarts can distinguish between habitat patches with different densities of food and preferentially exploit the most valuable. As our observations were made during bust conditions, experiments should be repeated during boom times to assess the foraging economics of dunnarts when environmental resources are high.

  13. Optimal foraging or predator avoidance: why does the Amazon spider Hingstepeira folisecens (Araneae: Araneidae adopt alternative foraging behaviors?

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    Kátia F. Rito

    Full Text Available ABSTRACT Strategies that increase foraging efficiency may also increase predation risk. We investigated how individuals of Hingstepeira folisecens Hingston, 1932, which build shelters at the orb hub, modulate their foraging behaviors in response to the trade-off between capturing prey and becoming exposed by leaving their shelters. We evaluated whether the position of the prey on the web alters the frequency at which spiders leave their shelters. Hingstepeira folisecens spiders were more likely to capture prey positioned below than above the entrance of the shelter. Moreover, when the prey was near the entrance of the shelter, the spider pulled the threads with the entangled prey without leaving the shelter. Conversely, when the prey was distant from the entrance of the shelter, an "attack" behavior (leaving the shelter was favored. We argue that the "pulling behavior" may be an adaptation to reduce exposure to predators.

  14. California Least Tern Foraging Ecology in Southern California: A Review of Foraging Behavior Relative to Proposed Dredging Locations

    Science.gov (United States)

    2016-05-01

    freshwater species, including killifish (Fundulus parvipinnis) and mosquito fish (Gambusia affinis) (Atwood and ERDC/EL CR-16-3 2 Kelly 1984...event of oil spill. Three portable pools with mosquito fish provided near Pier 400 nesting site. Included surveys at 3 preferred foraging areas...review summarized available information on CLT biology , ecology, and predators in the first four sections; Section 5 is entitled “Known Effects of

  15. Evaluation of yield and forage quality in main and ratoon crops of different sorghum lines

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    K.S. Vinutha

    2017-01-01

    Full Text Available Improving the yield and quality of sorghum (Sorghum bicolor forage for livestock feeding is a major breeding objective, because of sorghum’s inherently high biomass accumulation, high productivity per unit water utilized and its ability to produce a ratoon crop after harvesting of the plant crop. Newly bred sorghum lines, including 36 lines falling in 5 different categories, i.e. 12 experimental dual-purpose lines, 6 germplasm accessions from the ICRISAT collection, 11 commercial varieties and hybrids, 6 forage varieties and 1 bmr mutant line, were evaluated in terms of fodder yield, quality and ratooning ability. The main crop produced more dry biomass (P<0.05 at 80 days after planting (mean 22.87 t DM/ha; range 17.32‒33.82 t DM/ha than the ratoon crop (mean 8.47 t DM/ha; range 3.2‒17.42 t DM/ha after a further 80 days of growth. Mean nitrogen concentration in forage did not differ greatly between main and ratoon crops (2.56 vs. 2.40%, respectively but there was wide variation between lines (2.06‒2.89%. The line N 610 recorded highest N percentage of 2.89%, followed by SSG 59 3 (2.86% and SX 17 (2.81%. Highest acid detergent fiber % was recorded by ICSV 12008 (42.1%, closely followed by CO 31 and IS 34638 (40.0%. The least acid detergent lignin % was observed in MLSH-296 Gold (3.59%, ICSV 700 (3.75% and ICSSH 28 (3.83%. Metabolizable energy concentration was highest in N 610, Phule Yashodha and SX 17 (mean 8.34 MJ/kg DM, while in vitro organic matter digestibility ranged from 52.5 to 62.6%. The main crop contained much higher mean concentrations of the cyanogenic glycoside, dhurrin, than the ratoon (639 vs. 233 ppm, respectively with ranges of 38 to 2,298 ppm and 7 to 767 ppm, respectively. There was no significant correlation between dhurrin concentration and dry biomass yield so breeding and selection for low dhurrin concentrations should not jeopardize yields. Hence, breeding for sorghum can target simultaneously both quality and

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

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    Stout, Jane C.; Allen, John A.; Goulson, Dave

    2000-07-01

    In southern England, Linaria vulgaris (common yellow toadflax) suffers from high rates of nectar robbery by bumblebees. In a wild population of L. vulgaris we found that 96 % of open flowers were robbed. Five species of bumblebee were observed foraging on these flowers, although short-tongued species ( Bombus lapidarius, B. lucorum and B. terrestris) robbed nectar whilst longer-tongued ones behaved as legitimate pollinators ( B. hortorum and B. pascuorum). Nectar rewards were highly variable; on average there was less nectar in robbed than in unrobbed flowers, but this difference was not statistically significant. The proportion of flowers containing no nectar was significantly higher for robbed flowers compared with unrobbed flowers. Secondary robbers and legitimate pollinators had similar handling times on flowers and, assuming they select flowers at random to forage on, received approximately the same nectar profit per minute, largely because most flowers had been robbed. There was no significant difference in the number of seeds in pods of robbed flowers and in pods of flowers that were artificially protected against robbing. However, more of the robbed flowers set at least some seed than the unrobbed flowers, possibly as a consequence of the experimental manipulation. We suggest that nectar robbing has little effect on plant fecundity because legitimate foragers are present in the population, and that seed predation and seed abortion after fertilization may be more important factors in limiting seed production in this species.

  17. Nocturnal activity and foraging of prairie raccoons (Procyon lotor) in North Dakota

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    Greenwood, R.J.

    1982-01-01

    Nocturnal activity and foraging of 39 radio-equipped raccoons (Procyon lotor) in eastern North Dakota were studied from April-July in 1974-1976. Sixteen of the raccoons were collected after foraging bouts for stomach content analysis. Raccoon activity consisted of running (13%), walking (49%) and local movement in confined areas (38%). Local movement was foraging on large or locally abundant food items. Adult males traveled farther in a night, ran twice as often, and moved locally only half as often as adult females and yearlings. Differences in activity patterns between adult females and yearlings were not detected. There was no difference among age-sex groups in use of foraging habitats. All raccoons foraged extensively in farmyards and wetlands. Stomach content analysis substantiated foraging determinations obtained by radiotelemetry. Principal foods were grain, aquatic animals, rodents, birds and bird eggs.

  18. Effects of forage level and chromium-methionine chelate supplementation on performance, carcass characteristics and blood metabolites in Korean native (Hanwoo) steers.

    Science.gov (United States)

    Sung, Kyung-Il; Ghassemi Nejad, Jalil; Hong, Seok-Man; Ohh, Sang-Jip; Lee, Bae-Hun; Peng, Jing-Lun; Ji, Do-Hyeon; Kim, Byong-Wan

    2015-01-01

    A feeding trial was carried out to determine the effects of chromium methionine (Cr-Met) chelate and forage level over two years, 1(st) fattening and 2(nd) fattening period on growth parameters, carcass characteristics and blood metabolites of 46 Korean native (Hanwoo, Bos Taurus, BW = 183 ± 44 kg) steers. Treatments were: 1) Steers in the low forage (LF) group were fed diets that consisted of 60% concentrate and 40% forage; 2) Steers in the high forage (HF) group were fed diets that consisted of 40% concentrate and 60% forage. Following the 1(st) fattening period, steers (BW = 480 ± 37.6 kg) were randomly assigned to four treatment groups: LF (40 F plus no Cr-Met supplementation in the 2(nd) fattening period), LFCM (40LF plus added 400 ppb of Cr-Met during the 2(nd) fattening period), HF (60 F plus no added Cr-Met during the 2(nd) fattening period) and HFCM (60 F plus added 400 ppb of Cr-Met in the 2(nd) fattening period). Dry matter intake of the treatment diets did not differ during the raising and 1(th) fattening period (P > 0.05). The ADG in the raising period showed no difference between the 40 F and 60 F groups (P > 0.05). Carcass characteristics including rib-eye area and meat yield index were higher in HF than the other treatment groups (P 0.05). The Insulin concentration in the blood was significantly higher for the HFCM group than for the LF, LFCM and HF groups (P chelate could improve meat quality in beef steers.

  19. Trifolium isthmocarpum Brot, a salt-tolerant wild leguminous forage crop in salt-affected soils

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    Kawtar Bennani

    2013-08-01

    Full Text Available Plant scientists are investigating the potential of previously unexploited legume species where environmental and biological stresses constrain the use of more conventional forage crops or where these species are better suited to the needs of sustainable agriculture. Trifolium isthmocarpum Brot., Moroccan clover, occurs as a weed in different habitats in Morocco. It grows in moderately saline areas, where traditional forage legumes cannot be cultivated; however, it has not been widely studied despite its good palatability. The salt tolerance was studied between natural field conditions and glasshouse. The extensive field studies have recorded the species in many different habitats ranging from healthy agricultural lands to abandoned saline areas. The plants maintained high nodulation capacity (ranging between 60% and 97% and nitrogenase activities (average 2.04 µmol C2H4 plant-1 h-1 in different habitats. Shoot systems of plants collected from salt-affected soils exhibited higher concentrations of Na+ and Cl- than those collected from healthy soils. Greenhouse experiments showed that germination percentage and vigor value of the studied species was not significantly (P > 0.05 affected at 160 mM NaCl, and that 25% of the germination ability was maintained when growing on substrats containing 240 mM NaCl. The growth rate of seedlings was not signicantly affected by 160 mM NaCl but was reduced by 38% under 240 mM NaCl. Leaf succulence and indices of leaf water status did not differ among the salt treatments, whereas relative water content was reduced by only 8% and water content at saturation increased by about 12% at high salt concentrations in the growing medium. This study suggest recommending the cultivation of T. isthmocarpum in salt-affected soils, which are widespread and pose a problem for the farmers of Morocco and other countries in the world’s arid belt.

  20. Impacts of experimentally increased foraging effort on the family: offspring sex matters

    Science.gov (United States)

    Harding, A.M.A.; Kitaysky, A.S.; Hamer, K.C.; Hall, M.E.; Welcker, J.; Talbot, S.L.; Karnovsky, N.J.; Gabrielsen, G.W.; Gremillet, D.

    2009-01-01

    We examined how short-term impacts of experimentally increased foraging effort by one parent reverberate around the family in a monomorphic seabird (little auk, Alle alle), and whether these effects depend on offspring sex. In many species, more effort is required to rear sons successfully than daughters. However, undernourishment may have stronger adverse consequences for male offspring, which could result in a lower fitness benefit of additional parental effort when rearing a son. We tested two alternative hypotheses concerning the responses of partners to handicapping parents via feather clipping: partners rearing a son are (1) more willing or able to compensate for the reduced contribution of their mate, or (2) less willing or able to compensate, compared to those rearing a daughter. Hypothesis 1 predicts that sons will be no more adversely affected than daughters, and the impact on parents will be greater when rearing a son. Hypothesis 2 predicts that sons will be more adversely affected than daughters, and parents raising a son less affected. Although experimental chicks of both sexes fledged in poorer condition than controls, sons attained higher mass and more rapid growth than daughters in both groups. Clipped parents lost a similar proportion of their initial mass regardless of chick sex, whereas partners of clipped birds lost more mass when rearing a son. These results support hypothesis 1: impacts of increased foraging effort by one parent were felt by offspring, regardless of their sex, and by the partners of manipulated birds, particularly when the offspring was male. ?? 2009 The Association for the Study of Animal Behaviour.

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

    Science.gov (United States)

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

    2015-02-21

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

  2. Food limitation of sea lion pups and the decline of forage off central and southern California.

    Science.gov (United States)

    McClatchie, Sam; Field, John; Thompson, Andrew R; Gerrodette, Tim; Lowry, Mark; Fiedler, Paul C; Watson, William; Nieto, Karen M; Vetter, Russell D

    2016-03-01

    California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5-38° N) for a decade, suggesting that trends in forage are environmentally driven.

  3. Multiple-stage decisions in a marine central-place forager

    Science.gov (United States)

    Friedlaender, Ari S.; Johnston, David W.; Tyson, Reny B.; Kaltenberg, Amanda; Goldbogen, Jeremy A.; Stimpert, Alison K.; Curtice, Corrie; Hazen, Elliott L.; Halpin, Patrick N.; Read, Andrew J.; Nowacek, Douglas P.

    2016-01-01

    Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator–prey interactions and underscores the need to simultaneously measure prey distribution in marine central place

  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. Harvester Ant Colony Variation in Foraging Activity and Response to Humidity

    OpenAIRE

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

    2013-01-01

    Collective behavior is produced by interactions among individuals. Differences among groups in individual response to interactions can lead to ecologically important variation among groups in collective behavior. Here we examine variation among colonies in the foraging behavior of the harvester ant, Pogonomyrmex barbatus. Previous work shows how colonies regulate foraging in response to food availability and desiccation costs: the rate at which outgoing foragers leave the nest depends on the ...

  6. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies

    OpenAIRE

    Ellis, Samuel; Robinson, Elva J. H.

    2015-01-01

    A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non...

  7. A Hybrid Bacterial Foraging Algorithm For Solving Job Shop Scheduling Problems

    OpenAIRE

    Narendhar, S.; T Amudha

    2012-01-01

    Bio-Inspired computing is the subset of Nature-Inspired computing. Job Shop Scheduling Problem is categorized under popular scheduling problems. In this research work, Bacterial Foraging Optimization was hybridized with Ant Colony Optimization and a new technique Hybrid Bacterial Foraging Optimization for solving Job Shop Scheduling Problem was proposed. The optimal solutions obtained by proposed Hybrid Bacterial Foraging Optimization algorithms are much better when compared with the solution...

  8. Opportunities to enhance performance and efficiency through nutrient synchrony in forage-fed ruminants.

    Science.gov (United States)

    Hersom, M J

    2008-04-01

    Increasingly, the need for optimized nutrient utilization to address increasing production costs and environmental considerations will necessitate opportunities to improve nutrient synchrony. Historically, attempts at synchronizing nutrient supply in ruminants, particularly in cattle consuming high-forage diets, have met with variable results. The success of nutrient synchrony has been measured primarily in ruminants by increases in microbial yield, microbial efficiency, nutrient utilization, and to a lesser extent, animal performance. Successful synchrony of nutrient supply to cattle consuming forage-based diets faces several challenges. From a feed supply aspect, the challenges to nutrient synchrony include accurately measuring forage intake and consumed forage chemical composition. The issue of forage intake and chemical composition is perhaps the most daunting for producers grazing cattle. Indeed, for forage-fed cattle, the availability of forage protein and carbohydrate can be the most asynchronous aspect of the diet. In most grazed forages, digestion rates of the carbohydrate fractions are much slower than that of the corresponding protein fractions. Additionally, the forage-supplement interaction exerts a large impact on the synchrony of nutrients. The supplemental feedstuffs compose the component of the nutrient synchrony scenario that is most often manipulated to influence synchrony. The supplement type (e.g., starch vs. fiber, dry vs. liquid), nutrient profile, and degradation rates are often prime considerations associated with nutrient synchrony on high forage diets. Other considerations that warrant attention include temporal intake patterns of the forage and supplement, increased use and types of coproduct supplements, and an assessment of the success of nutrient synchrony. Synchronization of nutrient utilization by forage-fed ruminants has and will continue to encounter challenges for successful outcomes. Ultimately it is the improvement in animal

  9. Does foraging mode affect metabolic responses to feeding? A study of pygopodid lizards

    Directory of Open Access Journals (Sweden)

    Michael WALL, Michael B. THOMPSON, Richard SHINE

    2013-10-01

    Full Text Available Foraging mode (ambush vs. active profoundly affects many aspects of organismal biology, including metabolic rates and their relationship with food intake. Previous studies on snakes suggest that ambushers tend to have lower standard metabolic rates (SMR and higher energetic costs of digestion and assimilation of prey (specific dynamic action, or SDA than do active foragers. However, phylogenetic considerations may be at least partly responsible for such patterns, as foraging mode is strongly conserved evolutionarily and most SDA studies have focused on species from only two lineages of ambush foragers (pythonid and viperid snakes and one lineage of active foragers (colubrid snakes. We sought to deconfound the effects of phylogeny and foraging mode, investigating SMR and SDA in two closely related pygopodid lizards, the common scaly-foot Pygopus lepidopodus (active forager and Burton’s legless lizard Lialis burtonis (ambush forager. Consistent with the pattern seen in snakes, L. burtonis exhibits a significantly lower SMR and a higher SDA than does P. lepidopodus. The magnitude of SDA in L. burtonis is comparable to that of some pythons and vipers, providing yet more evidence for the remarkable convergence between this species and ambush-foraging snakes [Current Zoology 59 (5: 618–625, 2013]. 

  10. Diet Overlap and Foraging Activity between Feral Pigs and Native Peccaries in the Pantanal.

    Science.gov (United States)

    Galetti, Mauro; Camargo, Hiléia; Siqueira, Tadeu; Keuroghlian, Alexine; Donatti, Camila I; Jorge, Maria Luisa S P; Pedrosa, Felipe; Kanda, Claudia Z; Ribeiro, Milton C

    2015-01-01

    Inter-specific competition is considered one of the main selective pressures affecting species distribution and coexistence. Different species vary in the way they forage in order to minimize encounters with their competitors and with their predators. However, it is still poorly known whether and how native species change their foraging behavior in the presence of exotic species, particularly in South America. Here we compare diet overlap of fruits and foraging activity period of two sympatric native ungulates (the white-lipped peccary, Tayassu pecari, and the collared peccary, Pecari tajacu) with the invasive feral pig (Sus scrofa) in the Brazilian Pantanal. We found high diet overlap between white-lipped peccaries and feral pigs, but low overlap between collared peccaries and feral pigs. Furthermore, we found that feral pigs may influence the foraging period of both native peccaries, but in different ways. In the absence of feral pigs, collared peccary activity peaks in the early evening, possibly allowing them to avoid white-lipped peccary activity peaks, which occur in the morning. In the presence of feral pigs, collared peccaries forage mostly in early morning, while white-lipped peccaries forage throughout the day. Our results indicate that collared peccaries may avoid foraging at the same time as white-lipped peccaries. However, they forage during the same periods as feral pigs, with whom they have lower diet overlap. Our study highlights how an exotic species may alter interactions between native species by interfering in their foraging periods.

  11. 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.

  12. 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.

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

    Science.gov (United States)

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

    2015-07-07

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

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

    National Research Council Canada - National Science Library

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

    2015-01-01

    .... We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines...

  15. Foraging enrichment modulates open field response to monosodium glutamate in mice

    National Research Council Canada - National Science Library

    Onaolapo, Olakunle J; Onaolapo, Adejoke Y; Akanmu, Moses A; Olayiwola, Gbola

    2015-01-01

    Environmental enrichment can enhance expression of species-specific behaviour. While foraging enrichment is encouraged in laboratory animals, its impact on novelty induced behaviour remain largely unknown...

  16. Simulating secondary succession of elk forage values in a managed forest landscape, western Washington

    Science.gov (United States)

    Jenkins, Kurt J.; Starkey, Edward E.

    1996-01-01

    Modern timber management practices often influence forage production for elk (Cervus elaphus) on broad temporal and spatial scales in forested landscapes. We incorporated site-specific information on postharvesting forest succession and forage characteristics in a simulation model to evaluate past and future influences of forest management practices on forage values for elk in a commercially managed Douglas fir (Pseudotsuga menziesii, PSME)-western hemlock (Tsuga heterophylla, TSHE) forest in western Washington. We evaluated future effects of: (1) clear-cut logging 0, 20, and 40% of harvestable stands every five years; (2) thinning 20-year-old Douglas fir forests; and (3) reducing the harvesting cycle from 60 to 45 years. Reconstruction of historical patterns of vegetation succession indicated that forage values peaked in the 1960s and declined from the 1970s to the present, but recent values still were higher than may have existed in the unmanaged landscape in 1945. Increased forest harvesting rates had little short-term influence on forage trends because harvestable stands were scarce. Simulations of forest thinning also produced negligible benefits because thinning did not improve forage productivity appreciably at the stand level. Simulations of reduced harvesting cycles shortened the duration of declining forage values from approximately 30 to 15 years. We concluded that simulation models are useful tools for examining landscape responses of forage production to forest management strategies, but the options examined provided little potential for improving elk forages in the immediate future.

  17. Diet Overlap and Foraging Activity between Feral Pigs and Native Peccaries in the Pantanal.

    Directory of Open Access Journals (Sweden)

    Mauro Galetti

    Full Text Available Inter-specific competition is considered one of the main selective pressures affecting species distribution and coexistence. Different species vary in the way they forage in order to minimize encounters with their competitors and with their predators. However, it is still poorly known whether and how native species change their foraging behavior in the presence of exotic species, particularly in South America. Here we compare diet overlap of fruits and foraging activity period of two sympatric native ungulates (the white-lipped peccary, Tayassu pecari, and the collared peccary, Pecari tajacu with the invasive feral pig (Sus scrofa in the Brazilian Pantanal. We found high diet overlap between white-lipped peccaries and feral pigs, but low overlap between collared peccaries and feral pigs. Furthermore, we found that feral pigs may influence the foraging period of both native peccaries, but in different ways. In the absence of feral pigs, collared peccary activity peaks in the early evening, possibly allowing them to avoid white-lipped peccary activity peaks, which occur in the morning. In the presence of feral pigs, collared peccaries forage mostly in early morning, while white-lipped peccaries forage throughout the day. Our results indicate that collared peccaries may avoid foraging at the same time as white-lipped peccaries. However, they forage during the same periods as feral pigs, with whom they have lower diet overlap. Our study highlights how an exotic species may alter interactions between native species by interfering in their foraging periods.

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

    Science.gov (United States)

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

    2015-01-01

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

  19. 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.

  20. Life history, cognition and the evolution of complex foraging niches.

    Science.gov (United States)

    Schuppli, Caroline; Graber, Sereina M; Isler, Karin; van Schaik, Carel P

    2016-03-01

    Animal species that live in complex foraging niches have, in general, improved access to energy-rich and seasonally stable food sources. Because human food procurement is uniquely complex, we ask here which conditions may have allowed species to evolve into such complex foraging niches, and also how niche complexity is related to relative brain size. To do so, we divided niche complexity into a knowledge-learning and a motor-learning dimension. Using a sample of 78 primate and 65 carnivoran species, we found that two life-history features are consistently correlated with complex niches: slow, conservative development or provisioning of offspring over extended periods of time. Both act to buffer low energy yields during periods of learning, and may thus act as limiting factors for the evolution of complex niches. Our results further showed that the knowledge and motor dimensions of niche complexity were correlated with pace of development in primates only, and with the length of provisioning in only carnivorans. Accordingly, in primates, but not carnivorans, living in a complex foraging niche requires enhanced cognitive abilities, i.e., a large brain. The patterns in these two groups of mammals show that selection favors evolution into complex niches (in either the knowledge or motor dimension) in species that either develop more slowly or provision their young for an extended period of time. These findings help to explain how humans constructed by far the most complex niche: our ancestors managed to combine slow development (as in other primates) with systematic provisioning of immatures and even adults (as in carnivorans). This study also provides strong support for the importance of ecological factors in brain size evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. 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.

  2. Can video playback provide social information for foraging blue tits?

    Science.gov (United States)

    Hämäläinen, Liisa; Rowland, Hannah M; Mappes, Johanna; Thorogood, Rose

    2017-01-01

    Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits (Cyanistes caeruleus) videos of demonstrators discovering palatable or aversive prey (injected with bitter-tasting Bitrex) from coloured feeding cups. First we quantify variation in demonstrators' responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show that focal blue tits respond differently to the presence of a demonstrator on a video screen, depending on whether demonstrators discover palatable or aversive prey. Focal birds faced the video screen more during aversive prey presentations, and made more head turns. Regardless of prey type, focal birds also hopped more frequently during the presence of a demonstrator (compared to a control video of a different coloured feeding cup in an empty cage). Finally, we tested if demonstrators' behaviour affected focal birds' food preferences by giving individuals a choice to forage from the same cup as a demonstrator, or from the cup in the control video. We found that only half of the individuals made their choice in accordance to social information in the videos, i.e., their foraging choices were not different from random. Individuals that chose in accordance with a demonstrator, however, made their choice faster than individuals that chose an alternative cup. Together, our results suggest that video playback can provide social cues to blue tits, but individuals vary greatly in how they use this information in their foraging decisions.

  3. Can video playback provide social information for foraging blue tits?

    Directory of Open Access Journals (Sweden)

    Liisa Hämäläinen

    2017-03-01

    Full Text Available Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits (Cyanistes caeruleus videos of demonstrators discovering palatable or aversive prey (injected with bitter-tasting Bitrex from coloured feeding cups. First we quantify variation in demonstrators’ responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show that focal blue tits respond differently to the presence of a demonstrator on a video screen, depending on whether demonstrators discover palatable or aversive prey. Focal birds faced the video screen more during aversive prey presentations, and made more head turns. Regardless of prey type, focal birds also hopped more frequently during the presence of a demonstrator (compared to a control video of a different coloured feeding cup in an empty cage. Finally, we tested if demonstrators’ behaviour affected focal birds’ food preferences by giving individuals a choice to forage from the same cup as a demonstrator, or from the cup in the control video. We found that only half of the individuals made their choice in accordance to social information in the videos, i.e., their foraging choices were not different from random. Individuals that chose in accordance with a demonstrator, however, made their choice faster than individuals that chose an alternative cup. Together, our results suggest that video playback can provide social cues to blue tits, but individuals vary greatly in how they use this information in their foraging decisions.

  4. 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.

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

    Science.gov (United States)

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

    2010-01-01

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

  6. 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.

  7. Mucin glycan foraging in the human gut microbiome

    OpenAIRE

    Tailford, Louise E; Crost, Emmanuelle H.; Kavanaugh, Devon; Juge, Nathalie

    2015-01-01

    The availability of host and dietary carbohydrates in the gastrointestinal (GI) tract plays a key role in shaping the structure-function of the microbiota. In particular, some gut bacteria have the ability to forage on glycans provided by the mucus layer covering the GI tract. The O-glycan structures present in mucin are diverse and complex, consisting predominantly of core 1-4 mucin-type O-glycans containing α- and β- linked N-acetyl-galactosamine, galactose and N-acetyl-glucosamine. These c...

  8. Leucaena forage production trials based at Ciawi, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Petheram, R.J.; Pandjaitan, M.; Liano, J.

    1982-01-01

    Results from two village studies showed that dry matter yield of Leucaena leucocephala cultivar Cunningham was greater at a cutting height of 50 cm than at 10 cm and on weeded than on unweeded plots. Leucaena could be established in villages using seedlings raised in a seedbed, pulled at age 5 months and stored under wet sacks for 3-15 days before transplanting. This is cheaper than using seedlings in plastic pots. A brief description is given of an agroforestry system in West Timor that uses Leucaena as forage.

  9. Characterizing Variation of Isotopic Markers in Northern Alaskan Caribou Forages

    Science.gov (United States)

    VanSomeren, L.; Barboza, P. S.; Gustine, D. D.; Parrett, L. S.; Stricker, C. A.

    2013-12-01

    Isotopic markers in feces and tissues are a potential tool for monitoring the importance of feeding areas for migratory herbivores such as caribou (Rangifer tarandus). Many of these techniques are currently limited by gaps in our knowledge of how these isotopic signatures vary over the landscape. We collected seven species of preferred caribou forages along a latitudinal gradient in the summer ranges of the Central Arctic (9 sites) and Teshekpuk Lake (4 sites) caribou herds during 2011 and 2012. We analyzed forages at peak protein content and at the end of the season to characterize temporal, species-specific, and spatial variation in isotopic markers. The availability of C and N was measured by digestion in vitro. Isotopic signatures of digested samples were used to calculate fractionation that would bias the isotopic signature of feces. The range of values for isotopes (all values ‰) of nitrogen (δ15N -9.5 - +4.3), and sulfur (δ34S -3.6 - +15.5) were greater than those for carbon (δ13C -30.5 - -24.9). Small declines in forage δ13C with latitude (Carex aquatilis, Eriophorum vaginatum, Salix pulchra, and S. richardsonii [all P Sedges (Carex and Eriophorum) were significantly higher in δ15N than Salix spp. and other dicots (2.0 × 1.1 vs. -2.9 × 2.2; P < 0.01). For Salix spp., δ15N was consistent over the season and between years. Fractionation of δ15N in early season forages was 0.2 × 1.8 and not related to N availability (60% × 17%). For S. pulchra, δ34S may indicate usage of coastal habitats over foothills because δ34S was higher on the coastal plain than in the foothills (11.1 × 3.3 and 3.1 × 2.6; P < 0.01). Isotopic ratios in N and S show the greatest promise for tracking diet and location of migratory caribou whereas the narrow range in δ13C is affected by species, season and location.

  10. Collective Energy Foraging of Robot Swarms and Robot Organisms

    CERN Document Server

    Kernbach, Serge

    2011-01-01

    Cooperation and competition among stand-alone swarm agents increase collective fitness of the whole system. A principally new kind of collective systems is demonstrated by some bacteria and fungi, when they build symbiotic organisms. Symbiotic life forms emerge new functional and self-developmental capabilities, which allow better survival of swarm agents in different environments. In this paper we consider energy foraging scenario for two robotic species, swarm robots and symbiotic robot organism. It is indicated that aggregation of microrobots into a robot organism can provide better functional fitness for the whole group. A prototype of microrobots capable of autonomous aggregation and disaggregation are shown.

  11. Activity time budget during foraging trips of emperor penguins.

    Science.gov (United States)

    Watanabe, Shinichi; Sato, Katsufumi; Ponganis, Paul J

    2012-01-01

    We developed an automated method using depth and one axis of body acceleration data recorded by animal-borne data loggers to identify activities of penguins over long-term deployments. Using this technique, we evaluated the activity time budget of emperor penguins (n = 10) both in water and on sea ice during foraging trips in chick-rearing season. During the foraging trips, emperor penguins alternated dive bouts (4.8 ± 4.5 h) and rest periods on sea ice (2.5 ± 2.3 h). After recorder deployment and release near the colony, the birds spent 17.9 ± 8.4% of their time traveling until they reached the ice edge. Once at the ice edge, they stayed there more than 4 hours before the first dive. After the first dive, the mean proportions of time spent on the ice and in water were 30.8 ± 7.4% and 69.2 ± 7.4%, respectively. When in the water, they spent 67.9 ± 3.1% of time making dives deeper than 5 m. Dive activity had no typical diurnal pattern for individual birds. While in the water between dives, the birds had short resting periods (1.2 ± 1.7 min) and periods of swimming at depths shallower than 5 m (0.25 ± 0.38 min). When the birds were on the ice, they primarily used time for resting (90.3 ± 4.1% of time) and spent only 9.7 ± 4.1% of time traveling. Thus, it appears that, during foraging trips at sea, emperor penguins traveled during dives >5 m depth, and that sea ice was primarily used for resting. Sea ice probably provides refuge from natural predators such as leopard seals. We also suggest that 24 hours of sunlight and the cycling of dive bouts with short rest periods on sea ice allow emperor penguins to dive continuously throughout the day during foraging trips to sea.

  12. 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...

  13. Soil water dynamics and evapotranspiration of forage cactus clones under rainfed conditions

    Directory of Open Access Journals (Sweden)

    Thieres George Freire da Silva

    2015-07-01

    Full Text Available Abstract: The objective of this work was to evaluate soil water dynamics in areas cultivated with forage cactus clones and to determine how environmental conditions and crop growth affect evapotranspiration. The study was conducted in the municipality of Serra Talhada, in the state of Pernambuco, Brazil. Crop growth was monitored through changes in the cladode area index (CAI and through the soil cover fraction, calculated at the end of the cycle. Real evapotranspiration (ET of the three evaluated clones was obtained as the residual term in the soil water balance method. No difference was observed between soil water balance components, even though the evaluated clones were of different genus and had different CAI increments. Accumulated ET was of 1,173 mm during the 499 days of the experiment, resulting in daily average of 2.35 mm. The CAI increases the water consumption of the Orelha de Elefante Mexicana clone. In dry conditions, the water consumption of the Miúda clone responds more slowly to variation in soil water availability. The lower evolution of the CAI of the IPA Sertânia clone, during the rainy season, leads to a higher contribution of the evaporation component in ET. The atmospheric demand controls the ET of clones only when there is higher soil water availability; in this condition, the water consumption of the Miúda clone decreases more rapidly with the increase of atmospheric demand.

  14. Simulating mechanisms for dispersal, production and stranding of small forage fish in temporary wetland habitats

    Science.gov (United States)

    Yurek, Simeon; DeAngelis, Donald L.; Trexler, Joel C.; Jopp, Fred; Donalson, Douglas D.

    2013-01-01

    Movement strategies of small forage fish (stranded fish in accessible depths. Expansion and contraction of seasonal wetlands induce a sequential alternation between rapid biomass growth and concentration, creating the conditions for local stranding of small fish as they move in response to varying water levels. To better understand how landscape topography, hydrology, and fish behavior interact to create high densities of stranded fish, we first simulated population dynamics of small fish, within a dynamic food web, with different traits for movement strategy and growth rate, across an artificial, spatially explicit, heterogeneous, two-dimensional marsh slough landscape, using hydrologic variability as the driver for movement. Model output showed that fish with the highest tendency to invade newly flooded marsh areas built up the largest populations over long time periods with stable hydrologic patterns. A higher probability to become stranded had negative effects on long-term population size, and offset the contribution of that species to stranded biomass. The model was next applied to the topography of a 10 km × 10 km area of Everglades landscape. The details of the topography were highly important in channeling fish movements and creating spatiotemporal patterns of fish movement and stranding. This output provides data that can be compared in the future with observed locations of fish biomass concentrations, or such surrogates as phosphorus ‘hotspots’ in the marsh.

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

    Science.gov (United States)

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

    2011-08-10

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

  16. 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

  17. 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.

  18. Foraging activity rhythms of Dinoponera quadriceps (Hymenoptera: Formicidae) in its natural environment.

    Science.gov (United States)

    Medeiros, Jeniffer; Azevedo, Dina L O; Santana, Melquisedec A D; Lopes, Talita R P; Araújo, Arrilton

    2014-01-01

    This study characterizes the foraging activity of the queenless ant Dinoponera quadriceps (Kempf) (Hymenoptera: Formicidae) in its natural environment by testing the hypotheses that foraging activity presents both daily and seasonal rhythmic variations, and that these rhythms are related to environmental variables. Four colonies of D. quadriceps were observed in an area of secondary Atlantic forest in northeastern Brazil. Data collection was performed over 72 h every three months during an annual cycle. Both daily and seasonal foraging activity rhythms of D. quadriceps colonies were related to environmental factors, but colony differences also explained part of foraging variations. Foraging activity of D. quadriceps colonies was predominantly diurnal independently of season. In the early dry season, the colonies had two activity peaks, one in the morning and another in the afternoon, with a decrease in foraging at midday; however, during the rest of the year, foraging activity was distributed more evenly throughout the daylight hours. The daily rhythm of foraging activity was likely determined by an endogenous circadian rhythm year-round, but in the dry season, temperature and relative humidity also influenced daily foraging activity, with a negative effect of temperature and a positive effect of relative humidity. On a seasonal scale, foraging activity peaked in the early dry season and suddenly declined at the end of this season, increasing again at the late rainy season. The seasonal rhythm of foraging was negatively related to relative humidity and positively related to prey availability. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  19. Behavioral suites mediate group-level foraging dynamics in communities of tropical stingless bees.

    Science.gov (United States)

    Lichtenberg, E M; Imperatriz-Fonseca, V L; Nieh, J C

    2010-02-01

    Competition for floral resources is a key force shaping pollinator communities, particularly among social bees. The ability of social bees to recruit nestmates for group foraging is hypothesized to be a major factor in their ability to dominate rich resources such as mass-flowering trees. We tested the role of group foraging in attaining dominance by stingless bees, eusocial tropical pollinators that exhibit high diversity in foraging strategies. We provide the first experimental evidence that meliponine group foraging strategies, large colony sizes and aggressive behavior form a suite of traits that enable colonies to improve dominance of rich resources. Using a diverse assemblage of Brazilian stingless bee species and an array of artificial "flowers" that provided a sucrose reward, we compared species' dominance and visitation under unrestricted foraging conditions and with experimental removal of group-foraging species. Dominance does not vary with individual body size, but rather with foraging group size. Species that recruit larger numbers of nestmates (Scaptotrigona aff. depilis, Trigona hyalinata, Trigona spinipes) dominated both numerically (high local abundance) and behaviorally (controlling feeders). Removal of group-foraging species increased feeding opportunities for solitary foragers (Frieseomelitta varia, Melipona quadrifasciata and Nannotrigona testaceicornis). Trigona hyalinata always dominated under unrestricted conditions. When this species was removed, T. spinipes or S. aff. depilis controlled feeders and limited visitation by solitary-foraging species. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00040-009-0055-8) contains supplementary material, which is available to authorized

  20. 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

  1. Estimating yields of salt- and water-stressed forages with remote sensing in the visible and near infrared.

    Science.gov (United States)

    Poss, J A; Russell, W B; Grieve, C M

    2006-01-01

    In arid irrigated regions, the proportion of crop production under deficit irrigation with poorer quality water is increasing as demand for fresh water soars and efforts to prevent saline water table development occur. Remote sensing technology to quantify salinity and water stress effects on forage yield can be an important tool to address yield loss potential when deficit irrigating with poor water quality. Two important forages, alfalfa (Medicago sativa L.) and tall wheatgrass (Agropyron elongatum L.), were grown in a volumetric lysimeter facility where rootzone salinity and water content were varied and monitored. Ground-based hyperspectral canopy reflectance in the visible and near infrared (NIR) were related to forage yields from a broad range of salinity and water stress conditions. Canopy reflectance spectra were obtained in the 350- to 1000-nm region from two viewing angles (nadir view, 45 degrees from nadir). Nadir view vegetation indices (VI) were not as strongly correlated with leaf area index changes attributed to water and salinity stress treatments for both alfalfa and wheatgrass. From a list of 71 VIs, two were selected for a multiple linear-regression model that estimated yield under varying salinity and water stress conditions. With data obtained during the second harvest of a three-harvest 100-d growing period, regression coefficients for each crop were developed and then used with the model to estimate fresh weights for preceding and succeeding harvests during the same 100-d interval. The model accounted for 72% of the variation in yields in wheatgrass and 94% in yields of alfalfa within the same salinity and water stress treatment period. The model successfully predicted yield in three out of four cases when applied to the first and third harvest yields. Correlations between indices and yield increased as canopy development progressed. Growth reductions attributed to simultaneous salinity and water stress were well characterized, but the

  2. FORAGES AND PASTURES SYMPOSIUM: Improving efficiency of production in pasture- and range-based beef and dairy systems.

    Science.gov (United States)

    Mulliniks, J T; Rius, A G; Edwards, M A; Edwards, S R; Hobbs, J D; Nave, R L G

    2015-06-01

    Despite overall increased production in the last century, it is critical that grazing production systems focus on improving beef and dairy efficiency to meet current and future global food demands. For livestock producers, production efficiency is essential to maintain long-term profitability and sustainability. This continued viability of production systems using pasture- and range-based grazing systems requires more rapid adoption of innovative management practices and selection tools that increase profitability by optimizing grazing management and increasing reproductive performance. Understanding the genetic variation in cow herds will provide the ability to select cows that require less energy for maintenance, which can potentially reduce total energy utilization or energy required for production, consequently improving production efficiency and profitability. In the United States, pasture- and range-based grazing systems vary tremendously across various unique environments that differ in climate, topography, and forage production. This variation in environmental conditions contributes to the challenges of developing or targeting specific genetic components and grazing systems that lead to increased production efficiency. However, across these various environments and grazing management systems, grazable forage remains the least expensive nutrient source to maintain productivity of the cow herd. Beef and dairy cattle can capitalize on their ability to utilize these feed resources that are not usable for other production industries. Therefore, lower-cost alternatives to feeding harvested and stored feedstuffs have the opportunity to provide to livestock producers a sustainable and efficient forage production system. However, increasing production efficiency within a given production environment would vary according to genetic potential (i.e., growth and milk potential), how that genetic potential fits the respective production environment, and how the grazing

  3. Germinative potential of encrusted seed of tropical forage species

    Directory of Open Access Journals (Sweden)

    José Rafael de Souza

    Full Text Available ABSTRACT: Brazil is the largest producer, consumer and exporter of seeds of forage species, thus the adoption of new technologies for expansion and maintenance of this market is of great importance. The aim of this work was to evaluate encrustation effect on germination potential in seeds of Brachiaria sp. species. The experiment was carried out in Biofabrica laboratory from June to August 2014, in Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista-BA. The experimental design was completely randomized, in a factorial scheme 6x2, with two treatments (with and without coating and four replications. For germination quality of seeds were evaluated germination and vigor (emergence, emergence speed index, total length of seedling, shoot and root. The encrustation affected positively the germination of seeds in all species tested and encrustation did not affect the total length, shoot and root of the seedlings. Coating after chemical scarification is an alternative to improve germination of the seeds of tropical forage species.

  4. Foraging Path-length Protocol for Drosophila melanogaster Larvae.

    Science.gov (United States)

    Anreiter, Ina; Vasquez, Oscar E; Allen, Aaron M; Sokolowski, Marla B

    2016-04-23

    The Drosophila melanogaster larval path-length phenotype is an established measure used to study the genetic and environmental contributions to behavioral variation. The larval path-length assay was developed to measure individual differences in foraging behavior that were later linked to the foraging gene. Larval path-length is an easily scored trait that facilitates the collection of large sample sizes, at minimal cost, for genetic screens. Here we provide a detailed description of the current protocol for the larval path-length assay first used by Sokolowski. The protocol details how to reproducibly handle test animals, perform the behavioral assay and analyze the data. An example of how the assay can be used to measure behavioral plasticity in response to environmental change, by manipulating feeding environment prior to performing the assay, is also provided. Finally, appropriate test design as well as environmental factors that can modify larval path-length such as food quality, developmental age and day effects are discussed.

  5. Nitrogen use efficiency in forage yield of tropical maize populations

    Directory of Open Access Journals (Sweden)

    Leandro Lopes Cancellier

    2014-06-01

    Full Text Available The development of adapted cultivars to nitrogen stress conditions is shown as an ecologically sustainable option to ensure higher yields in low input agricultural systems. This study aimed to evaluate the NUE in tropical maize (Zea mays L. populations to forage production in the south of the State of Tocantins. Two experiments were done corresponding to low and high N availability sown on November 21, 2009. Twenty four maize populations and a commercial cultivar BR 106 were used in the experiments. The experimental design was a randomized block with two replicates. Plant height, ear height, ear participation in plant total green mass, ear green mass; plant green mass without ear, total green mass and NUE in forage production were evaluated. Through Moll methodology differences among populations for nitrogen use efficiency were found, however these differences weren’t found on Fischer methodology. Populations 12-4, 1-3, 12-6, 12-5, 26-1, 15-2, 25-2 and 1-5 are considered efficient in nitrogen use. The populations 12-6, 12-5, 12-4, 1-3, 1-4, 1-5 and 15-2 are the best populations to use in high and low N environment, combining great production of green mass and being efficient in N use.

  6. Error in the honeybee waggle dance improves foraging flexibility.

    Science.gov (United States)

    Okada, Ryuichi; Ikeno, Hidetoshi; Kimura, Toshifumi; Ohashi, Mizue; Aonuma, Hitoshi; Ito, Etsuro

    2014-02-26

    The honeybee waggle dance communicates the location of profitable food sources, usually with a certain degree of error in the directional information ranging from 10-15° at the lower margin. We simulated one-day colonial foraging to address the biological significance of information error in the waggle dance. When the error was 30° or larger, the waggle dance was not beneficial. If the error was 15°, the waggle dance was beneficial when the food sources were scarce. When the error was 10° or smaller, the waggle dance was beneficial under all the conditions tested. Our simulation also showed that precise information (0-5° error) yielded great success in finding feeders, but also caused failures at finding new feeders, i.e., a high-risk high-return strategy. The observation that actual bees perform the waggle dance with an error of 10-15° might reflect, at least in part, the maintenance of a successful yet risky foraging trade-off.

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

    Science.gov (United States)

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

    2016-09-01

    We study the dynamics of a starving random walk in general spatial dimension d. This model represents an idealized description for the fate of an unaware forager whose motion is not affected by the presence or absence of resources. The forager depletes its environment by consuming resources and dies if it wanders too long without finding food. In the exactly solvable case of one dimension, we explicitly derive the average lifetime of the walk and the distribution for the number of distinct sites visited by the walk at the instant of starvation. We also give a heuristic derivation for the averages of these two quantities. We tackle the complex but ecologically relevant case of two dimensions by an approximation in which the depleted zone is assumed to always be circular and which grows incrementally each time the walk reaches the edge of this zone. Within this framework, we derive a lower bound for the scaling of the average lifetime and number of distinct sites visited at starvation. We also determine the asymptotic distribution of the number of distinct sites visited at starvation. Finally, we solve the case of high spatial dimensions within a mean-field approach.

  8. Energetics of foraging and locomotion in the platypus Ornithorhynchus anatinus.

    Science.gov (United States)

    Bethge, P; Munks, S; Nicol, S

    2001-08-01

    We measured the energy requirements of platypuses foraging, diving and resting in a swim tank using flow-through respirometry. Also, walking metabolic rates were obtained from platypuses walking on a conventional treadmill. Energy requirements while foraging were found to depend on water temperature, body weight and dive duration and averaged 8.48 W kg(-1). Rates for subsurface swimming averaged 6.71 W kg(-1). Minimal cost of transport for subsurface swimming platypuses was 1.85 J N(-1)m(-1) at a speed of 0.4 m s(-1). Aerobic dive limit of the platypus amounted to 59 s. Metabolic rate of platypuses resting on the water surface was minimal with 3.91 W kg(-1) while minimal RMR on land was 2.08 W kg(-1). The metabolic rate for walking was 8.80 W kg(-1) and 10.56 W kg(-1) at speeds of 0.2 m s(-1) and 0.3 m s(-1), respectively. A formula was derived, which allows prediction of power requirements of platypuses in the wild from measurements of body weight, dive duration and water temperature. Platypuses were found to expend energy at only half the rate of semiaquatic eutherians of comparable body sizes during both walking and diving. However, costs of transport at optimal speed were in line with findings for eutherians. These patterns suggest that underwater locomotion of semiaquatic mammals have converged on very similar efficiencies despite differences in phylogeny and locomotor mode.

  9. 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.

  10. MORPHOLOGICAL AND PRODUCTIVE CHARACTERIZATION OF FORAGE CACTUS VARIETIES

    Directory of Open Access Journals (Sweden)

    PHILIPE LIMA DE AMORIM

    2015-01-01

    Full Text Available Cultivars of the genus Nopalea are known in Brazil for being tolerant to cochineal carmine attacks, thus making the cultivation of this genus a promising alternative for mitigating the negative effects of this insect on the production of biomass. With the objectives of characterizing morphologically spineless forage cactus varieties and identify morphological characteristics that may be the focus in spineless forage cactus breeding programs, an experiment was conducted in a completely randomized block design with 11 treatments and four replications. The variety Alagoas showed the highest values of weight, area and volume of cladodes. The varieties Negro Michoacan F7 and V7, Tamazunchale V12 showed the highest values of the cladode area index, the total volume of cladodes and total fresh mass production. The varieties Negro Michoacan V7 and F7 presented the highest water use efficiency and dry mass yield. Cladode volume showed the highest correlation coefficients with the fresh weight of cladodes. Aiming the release of varieties for biomass production, varieties Negro Michoacan F7, V7 and Tamazunchale V12 may substitute the Miúda variety. The number and cladode area index may be used as criteria for selection of superior varieties in breeding programs.

  11. Memory Effects on Movement Behavior in Animal Foraging.

    Directory of Open Access Journals (Sweden)

    Chloe Bracis

    Full Text Available An individual's choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk. We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.

  12. 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.

  13. Identifying Winter Forage Triticale (X Triticosecale Wittmack) Strains for the Central Great Plains

    Science.gov (United States)

    Triticale (X Triticosecale Wittmack), a human-made crop, is mainly used as a forage crop in the central Great Plains. A successful triticale cultivar should have high forage yield with good quality, and also high grain yield so the seed can be economically produced. Hence, the purpose of this study...

  14. 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.

  15. Effect of species and harvest maturity on the fatty acids profile of tropical forages

    NARCIS (Netherlands)

    Khan, N.A.; Farooq, M.W.; Ali, M.; Suleman, M.; Ahmad, N.; Sulaiman, S.M.; Cone, J.W.; Hendriks, W.H.

    2015-01-01

    The aim of this study was to quantify the fatty acid (FA) content and composition of forages commonly fed to dairy animals in the tropics. Twelve forage species, namely, Trifolium alexandrinum, Cichorium intybus, Hordeum vulgare L., Medicago sativa, Avena sativa, Pennisetum purpureum Setaria anceps,

  16. Annual variation in foraging ecology of prothonotary warblers during the breeding season

    Science.gov (United States)

    Petit, L.J.; Petit, D.R.; Petit, K.E.; Fleming, W.J.

    1990-01-01

    We studied foraging ecology of Prothonotary Warblers (Protonotaria citrea) along the Tennessee River in west-central Tennessee during the breeding seasons of 1984-1987. We analyzed seven foraging variables to determine if this population exhibited annual variation in foraging behavior. Based on nearly 3,000 foraging maneuvers, most variables showed significant interyear variation during the four prenestling and three nestling periods we studied. This interyear variation probably was due -to proximate, environmental cues--such as distribution and abundance of arthropods--which, in turn, were influenced by local weather conditions. Researchers should consider the consequences of combining foraging behavior data collected in different years, because resolution of ecological trends may be sacrificed by considering only general patterns of foraging ecology and not the dynamics of those activities. In addition, because of annual variability, foraging data collected in only one year, regardless of the number of observations gathered, may not provide an accurate concept of the foraging ecology in insectivorous birds.

  17. Linkage between fishes'foraging, market and fish stocks density: Examples from some North Sea fisheries

    NARCIS (Netherlands)

    Marchal, P.; Poos, J.J.; Quirijns, F.J.

    2007-01-01

    This study has investigated some properties of fishermen's foraging, using Levy flights theory. The case studies examined were a selection of North Sea Dutch and French vessels, for which catch and effort data were collected on a haul-by-haul basis. Foraging behavior could reasonably be represented

  18. 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...

  19. Untying the knot: mechanistically understanding the interactions between social foragers and their prey

    NARCIS (Netherlands)

    Bijleveld, A.I.

    2015-01-01

    An entire flyway of shorebirds is dependent on the Dutch Wadden Sea. Here they find food to survive or fuel their flights towards the Arctic or Africa. Most shorebirds feed on worms and shellfish hiding in the mud. The work presented in this thesis concerns the foraging decisions of a socially forag

  20. Moving on with foraging theory: incorporating movement decisions into the functional response of a gregarious shorebird

    NARCIS (Netherlands)

    van Gils, J.A.; van der Geest, M.; De Meulenaer, B.; Gillis, H.; Piersma, T.; Folmer, E.O.

    2015-01-01

    1.Models relating intake rate to food abundance and competitor density (generalized functional response models) can predict forager distributions and movements between patches, but we lack understanding of how distributions and small-scale movements by the foragers themselves affect intake rates.2.U

  1. Moving on with foraging theory : Incorporating movement decisions into the functional response of a gregarious shorebird

    NARCIS (Netherlands)

    van Gils, Jan A; van der Geest, Matthijs; De Meulenaer, Brecht; Gillis, Hanneke; Piersma, Theunis; Folmer, Eelke O

    2015-01-01

    Models relating intake rate to food abundance and competitor density (generalized functional response models) can predict forager distributions and movements between patches, but we lack understanding of how distributions and small-scale movements by the foragers themselves affect intake rates. Usin

  2. Dry season mapping of savanna forage quality, using the hyperspectral Carnegie

    NARCIS (Netherlands)

    Knox, N.; Skidmore, A.K.; Prins, H.H.T.; Asner, P.; Werff, van der H.M.A.; Boer, de W.F.; Waal, van der C.; Knegt, de H.J.; Kohi, E.; Slotow, R.; Grant, R.C.

    2011-01-01

    Forage quality within an African savanna depends upon limiting nutrients (nitrogen and phosphorus) and nutrients that constrain the intake rates (non-digestible fibre) of herbivores. These forage quality nutrients are particularly crucial in the dry season when concentrations of limiting nutrients d

  3. The evolution of foraging rate across local and geographic gradients in predation risk and competition.

    Science.gov (United States)

    Urban, Mark C; Richardson, Jonathan L

    2015-07-01

    Multiple theories predict the evolution of foraging rates in response to environmental variation in predation risk, intraspecific competition, time constraints, and temperature. We tested six hypotheses for the evolution of foraging rate in 24 spotted salamander (Ambystoma maculatum) populations from three latitudinally divergent sites using structural equation models derived from theory and applied to our system. We raised salamander larvae in a common-garden experiment and then assayed foraging rate under controlled conditions. Gape-limited predation risk from marbled salamanders solely explained foraging rate variation among populations at the southern site, which was dominated by this form of selection. However, at the middle and northern sites, populations evolved different foraging rates depending on their unique responses to local intraspecific density. The coupling of gape-limited predation risk from marbled salamanders and high intraspecific density at the middle site jointly contributed to selection for rapid foraging rate. At the northernmost site, intraspecific density alone explained 97% of the interpopulation variation in foraging rate. These results suggest that foraging rate has evolved multiple times in response to varying contributions from predation risk and intraspecific competition. Predation risk often varies along environmental gradients, and, thus, organisms might often shift evolutionary responses from minimizing predation risk to maximizing intraspecific competitive performance.

  4. Patch densities determines movement patterns and foraging efficiency of large herbivores

    NARCIS (Netherlands)

    Knegt, de H.J.; Hengeveld, G.M.; Langevelde, van F.; Boer, de W.F.; Kirkman, K.P.

    2007-01-01

    Few experimental studies have tested theoretical predictions regarding the movement strategies of large herbivores and their consequences for foraging efficiency. We therefore analyze how the movement and foraging behavior of goats are related to patch density, with patches being trees and bushes. W

  5. Anaerobic co-digestion of forage radish and dairy manure in complete mix digesters

    Science.gov (United States)

    Farmers are increasingly using forage radish as a winter cover crop to achieve multiple soil and environmental benefits. In this study, pilot-scale mixed digesters were used to quantify methane (CH4) and hydrogen sulfide (H2S) production when using forage radish, a sulfur-rich cover crop, as a co-d...

  6. 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...

  7. Foraging recruitment by the Giant Tropical Ant Paraponera clavata (Hymenoptera, Formicidae)

    Science.gov (United States)

    Barrett, Bruce A.; Jorgenson, Clive D.; Looman, Sandra J.

    1985-01-01

    Increased foraging of an exceptionally abundant, but ephemeral, food source by ants can result from foraging excitement that does not include pheromone trails, tandem running, or from recruitment of other workers along pheromone trails (Carrol and Janzen, 1973). They also provided rationale for two types of short-lived pheromone trails resulting in mass or group recruitment. These both seem to fall into the Type II foraging strategy described by Oster and Wilson (1978). Neither of these discussions conveniently allow for pheromone recruitment by relatively small colonies of a primitive monomorphic species such as Paraponera clavata. Our observations suggest that recruitment to an abundant ephemeral food source does occur naturally and can be induced artificially in colonies of P. clavata.Paraponera clavata is considered primitive (Wilson, 1958), particularly in foraging habits (Young and Hermann, 1980; Young, 1977). Hermann (1973, 1975) reported the P. clavata, unlike more advanced species, forages independently; following shot periods of apparent group activity outside of the colony (Young and Hermann, 1980). It reportedly does not return to a food source when only part has been harvested. After returning to its colony with booty, a single worker resumes foraging independently, with no observable tendency to return to partially harvested booty or without recruiting additional workers to collect the remaining food (Hermann, 1973; Young and Hermann, 1980). Reports of independent foraging, lack of forager recruitment, and apparent lack of food source fidelity resulted in the assumption that P. clavata probably lacks an effective pheromone trail communication system (Young and Hermann, 1980).

  8. The rewards of restraint in the collective regulation of foraging by harvester ant colonies.

    Science.gov (United States)

    Gordon, Deborah M

    2013-06-06

    Collective behaviour, arising from local interactions, allows groups to respond to changing conditions. Long-term studies have shown that the traits of individual mammals and birds are associated with their reproductive success, but little is known about the evolutionary ecology of collective behaviour in natural populations. An ant colony operates without central control, regulating its activity through a network of local interactions. This work shows that variation among harvester ant (Pogonomyrmex barbatus) colonies in collective response to changing conditions is related to variation in colony lifetime reproductive success in the production of offspring colonies. Desiccation costs are high for harvester ants foraging in the desert. More successful colonies tend to forage less when conditions are dry, and show relatively stable foraging activity when conditions are more humid. Restraint from foraging does not compromise a colony's long-term survival; colonies that fail to forage at all on many days survive as long, over the colony's 20-30-year lifespan, as those that forage more regularly. Sensitivity to conditions in which to reduce foraging activity may be transmissible from parent to offspring colony. These results indicate that natural selection is shaping the collective behaviour that regulates foraging activity, and that the selection pressure, related to climate, may grow stronger if the current drought in their habitat persists.

  9. 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.

  10. Small is profitable: No support for the optimal foraging theory in sea stars

    NARCIS (Netherlands)

    Hummel, C.; Honkoop, P.; van der Meer, J.

    2011-01-01

    Doubt has been shed recently on the most popular optimal foraging theory stating that predators should maximize prey profitability, i.e., select that prey item that contains the highest energy content per handling time. We hypothesized that sea stars do not forage on blue mussels according to the cl

  11. Combined foraging strategies and soldier behaviour in Nasutitermes aff. coxipoensis (Blattodea: Termitoidea: Termitidae).

    Science.gov (United States)

    Almeida, Camilla S; Cristaldo, Paulo F; Florencio, Daniela F; Cruz, Nayara G; Santos, Abraão A; Oliveira, Alexandre P; Santana, Alisson S; Ribeiro, Efrem J M; Lima, Ana P S; Bacci, Leandro; Araújo, Ana P A

    2016-05-01

    A range of behavioural strategies and sensory abilities allows animals to minimize costs involved in food search. By building a network of tunnels and presenting a large number of soldiers (i.e., trophically dependent individuals), Nasutitermes spp. termites feature behaviours that imply additional costs during this process. Here we evaluated N. aff. coxipoensis foraging strategies focusing on the role of soldiers during foraging. Field experiments were carried out via nests transplantation to dune areas, and laboratory experiments evaluated termite responses to sternal gland chemical signals from workers and soldiers. N. aff. coxipoensis presented primarily nocturnal foraging. Soldiers typically initiated foraging; however, in established trails, the number of workers was always higher than that of soldiers. The number of trails remained constant over time, while the number of tunnels increased linearly over time. A higher proportion of tunnels originated in surrounding areas than directly from the nests. At observation points with tunnels, there were more stationary than walking soldiers; the opposite was true at observation points without tunnels. In mixed groups, the workers chose to follow soldier chemical signals, and in these groups, soldiers were the first to follow trails. Our results allowed us to identify a not common foraging strategy in termite species; which included the establishment of trails followed by construction of tunnels. Such foraging strategies occur predominantly at night and soldiers play a key role in the foraging process. This foraging strategy reported here seems to be employed to optimize energetic gain.

  12. Assessing herbivore foraging behavior with GPS collars in a semiarid grassland

    Science.gov (United States)

    Advances in global positioning system (GPS) technology have dramatically enhanced the ability to track and study distributions of free-ranging livestock. However, understanding factors controlling livestock foraging distribution requires the ability to assess when and where they are foraging. We col...

  13. Information from familiar and related conspecifics affects foraging in a solitary wolf spider.

    Science.gov (United States)

    Hoffman, Catherine R; Sitvarin, Michael I; Rypstra, Ann L

    2016-06-01

    As neighbours become familiar with one another, they can divert attention away from one another and focus on other activities. Since familiarity is a likely mechanism by which animals recognise relatives, both kinship and prior association with conspecifics should allow individuals to increase foraging. We attempted to determine if the interference observed among conspecific foragers could be mitigated by familiarity and/or kinship. Because Pardosa milvina wolf spiders are sensitive to chemotactile cues deposited on substrates by other spiders, we used cues to manipulate the information available to focal spiders. We first verified that animals could use these cues to differentiate relatives and familiar conspecifics. We then documented foraging in the presence of all combinations of related and familiar animal cues. Test spiders were slower foragers, less likely to capture prey, and consumed less of each prey item when on cues from unfamiliar kin, but were faster and more effective foragers on cues from familiar non-kin. Their reactions to familiar kin and unfamiliar non-kin were intermediate. High foraging intensity on familiar cues is consistent with the idea that animals pay less attention to neighbours after some prior association. Lower foraging effort in the presence of cues from relatives may be an attempt to reduce kin competition by shifting attention toward dispersal or to provide increased access to prey for hungry relatives nearby. These findings reveal that information from conspecifics mediates social interactions among individuals and affects foraging in ways that can influence their role in the food web.

  14. The foraging benefits of being fat in a highly migratory marine mammal.

    Science.gov (United States)

    Adachi, Taiki; Maresh, Jennifer L; Robinson, Patrick W; Peterson, Sarah H; Costa, Daniel P; Naito, Yasuhiko; Watanabe, Yuuki Y; Takahashi, Akinori

    2014-12-22

    Foraging theory predicts that breath-hold divers adjust the time spent foraging at depth relative to the energetic cost of swimming, which varies with buoyancy (body density). However, the buoyancy of diving animals varies as a function of their body condition, and the effects of these changes on swimming costs and foraging behaviour have been poorly examined. A novel animal-borne accelerometer was developed that recorded the number of flipper strokes, which allowed us to monitor the number of strokes per metre swam (hereafter, referred to as strokes-per-metre) by female northern elephant seals over their months-long, oceanic foraging migrations. As negatively buoyant seals increased their fat stores and buoyancy, the strokes-per-metre increased slightly in the buoyancy-aided direction (descending), but decreased significantly in the buoyancy-hindered direction (ascending), with associated changes in swim speed and gliding duration. Overall, the round-trip strokes-per-metre decreased and reached a minimum value when seals achieved neutral buoyancy. Consistent with foraging theory, seals stayed longer at foraging depths when their round-trip strokes-per-metre was less. Therefore, neutrally buoyant divers gained an energetic advantage via reduced swimming costs, which resulted in an increase in time spent foraging at depth, suggesting a foraging benefit of being fat.

  15. Behavioural responses of Eastern grey squirrels, Sciurus carolinensis, to cues of risk while foraging.

    Science.gov (United States)

    Jayne, Kimberley; Lea, Stephen E G; Leaver, Lisa A

    2015-07-01

    Previous studies have shown that Eastern grey squirrels modify their behaviour while foraging to offset risks of social and predatory costs, but none have simultaneously compared whether such modifications are performed at a cost to foraging. The present study directly compares how grey squirrels respond to cues of these risks while foraging. We simulated social risk and predatory risk using acoustic playbacks of stimuli that grey squirrels might be exposed to at a foraging patch: calls of conspecifics, heterospecifics (competitor and non-competitor) and predators. We found that grey squirrels responded to predator, heterospecific competitor and conspecific playbacks by altering their foraging and vigilance behaviours. Foraging was most disrupted by increased vigilance when we played calls of predators. Squirrels' response to calls of heterospecific competitors did not differ from their response to conspecific calls, and they resumed foraging more quickly after both compared to predator calls: whereas they showed little response to calls of non-competitor heterospecifics and a white noise control. We conclude that squirrels respond differentially to calls made by conspecifics, heterospecific competitors and predators, with the most pronounced response being to calls of predators. We suggest that squirrels may view conspecific and corvid vocalisations as cues of potential conflict while foraging, necessitating increased vigilance.

  16. Foraging innovation is inversely related to competitive ability in male but not in female guppies

    NARCIS (Netherlands)

    Laland, K.N.; Reader, S.M.

    1999-01-01

    Foraging success is likely to affect hunger level and motivation to locate and exploit novel food sources in animals. We explored the relationship between scramble competition for limited food and foraging innovation in the guppy (Poecilia reticulata), predicting that poor competitors would be more

  17. 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...

  18. Foraging innovation is inversely related to competitive ability in male but not in female guppies

    NARCIS (Netherlands)

    Laland, K.N.; Reader, S.M.

    1999-01-01

    Foraging success is likely to affect hunger level and motivation to locate and exploit novel food sources in animals. We explored the relationship between scramble competition for limited food and foraging innovation in the guppy (Poecilia reticulata), predicting that poor competitors would be more

  19. Foraging decisions in wild versus domestic Mus musculus: What does life in the lab select for?

    Science.gov (United States)

    Troxell-Smith, Sandra M; Tutka, Michal J; Albergo, Jessica M; Balu, Deebika; Brown, Joel S; Leonard, John P

    2016-01-01

    What does domestication select for in terms of foraging and anti-predator behaviors? We applied principles of patch use and foraging theory to test foraging strategies and fear responses of three strains of Mus musculus: wild-caught, control laboratory, and genetically modified strains. Foraging choices were quantified using giving-up densities (GUDs) under three foraging scenarios: (1) patches varying in microhabitat (covered versus open), and initial resource density (low versus high); (2) daily variation in auditory cues (aerial predators and control calls); (3) patches with varying seed aggregations. Overall, both domestic strains harvested significantly more food than wild mice. Each strain revealed a significant preference for foraging under cover compared to the open, and predator calls had no detectable effects on foraging. Both domestic strains biased their harvest toward high quality patches; wild mice did not. In terms of exploiting favorable and avoiding unfavorable distributions of seeds within patches, the lab strain performed best, the wild strain worst, and the mutant strain in between. Our study provides support for hypothesis that domestic animals have more energy-efficient foraging strategies than their wild counterparts, but retain residual fear responses. Furthermore, patch-use studies can reveal the aptitudes and priorities of both domestic and wild animals.

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

    Science.gov (United States)

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