Foraging Activity in Plebeia remota, a Stingless Bees Species, Is Influenced by the Reproductive State of a Colony

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Patrícia Nunes-Silva

2010-01-01

Full Text Available Colonies of the Brazilian stingless bee Plebeia remota show a reproductive diapause in autumn and winter. Therefore, they present two distinct reproductive states, during which colony needs are putatively different. Consequently, foraging should be adapted to the different needs. We recorded the foraging activity of two colonies for 30 days in both phases. Indeed, it presented different patterns during the two phases. In the reproductive diapause, the resource predominantly collected by the foragers was nectar. The majority of the bees were nectar foragers, and the peak of collecting activity occurred around noon. Instead, in the reproductive phase, the predominantly collected resource was pollen, and the peak of activity occurred around 10:00 am. Although the majority of the foragers were not specialized in this phase, there were a larger number of pollen foragers compared to the phase of reproductive diapause. The temperature and relative humidity also influenced the foraging activity.

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

Science.gov (United States)

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

2014-01-14

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

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

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M. R. Islam

2015-05-01

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

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

Science.gov (United States)

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

2015-05-01

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

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

OpenAIRE

Wikelski, Martin; Trillmich, Fritz

1994-01-01

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

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

DEFF Research Database (Denmark)

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

2010-01-01

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

Does greed help a forager survive?

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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.

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

NARCIS (Netherlands)

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

2010-01-01

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

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

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Michael eRivera

2015-05-01

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

Forage selection by Royle's pika (Ochotona roylei) in the western Himalaya, India.

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Bhattacharyya, Sabuj; Adhikari, Bhupendra S; Rawat, Gopal S

2013-10-01

Forage selection decisions of herbivores are often complex and dynamic; they are modulated by multiple cues, such as quality, accessibility and abundance of forage plants. To advance the understanding of plant-herbivore interactions, we explored foraging behavior of the alpine lagomorph Royle's pika (Ochotona roylei) in Kedarnath Wildlife Sanctuary, India. Pika bite counts on food plants were recorded through focal sampling in three permanently marked plots. Food plant abundance was recorded by traditional quadrat procedures; forage selection was estimated with Jacob's selection index. Multiple food-choice experiments were conducted to determine whether forage selection criteria would change with variation in food plant composition. We also analyzed leaf morphology and nutrient content in both major food plants and abundantly available non-food plants. Linear regression models were used to test competing hypotheses in order to identify factors governing forage selection. Royle's pika fed primarily on 17 plant species and each forage selection decision was positively modulated by leaf area and negatively modulated by contents of avoided substances (neutral detergent fiber, acid detergent fiber, acid detergent lignin and tannin) in food plants. Furthermore, significance of the interaction term "leaf size × avoided substance" indicates that plants with large leaves were selected only when they had low avoided substance content. The forage selection criteria did not differ between field and laboratory experiments. The parameter estimates of best fit models indicate that the influence of leaf size or amount of avoided substance on pika forage selection was modulated by the magnitude of predation risk. Copyright © 2013 Elsevier GmbH. All rights reserved.

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

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

2018-04-01

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

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.

New Developments in Forage Varieties

Science.gov (United States)

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

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…

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

NARCIS (Netherlands)

Biesmeijer, J.C.; Tóth, E.

1998-01-01

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

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

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Daiane Cristine Seibt

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

Sympatric cattle grazing and desert bighorn sheep foraging

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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

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

OpenAIRE

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

2016-01-01

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

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

African Journals Online (AJOL)

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

Food of forage fishes in western Lake Erie, 1975-76

Science.gov (United States)

Muth, Kenneth M.; Busch, Wolf-Dieter N.

1989-01-01

In western Lake Erie in the summer and fall of 1975–1976, food eaten by seven forage fishes—emerald shiner (Notropis atherinoides), spottail shiner (Notropis hudsonius), trout-perch (Percopsis omiscomaycus), andyoung-of-the-year (YOY) of alewife (Alosa pseudoharengus), gizzard shad (Dorosoma cepedianum), white bass (Morone chrysops), and freshwater drum (Aplodi-notus grunniens)—was divided among six major taxa: Cladocera, Copepoda, Diptera, Ostracoda, Amphipoda, and Algae. In addition, fish were eaten by YOY white bass, and Rotifera were consumed by YOY gizzard shad. Interspecies diet overlap indices, calculated to compare the food of the different species and to evaluate diet similarities, were usually highest for YOY white bass and YOY freshwater drum when compared with the other species and usually lowest between emerald shiners and all other forage fishes. Understanding the feeding interactions among fishes that could influence production at the forage-food level of the food web could provide insight into how cascading trophic interactions influence the production of piscivorous predators.

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

International Nuclear Information System (INIS)

Peschke, H.

1981-01-01

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

Adaptive Bacterial Foraging Optimization

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Hanning Chen

2011-01-01

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

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

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Jean Jules Tewa

2014-01-01

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

Boa constrictor (Boa constrictor): foraging behavior

Science.gov (United States)

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

2011-01-01

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

Visual Foraging With Fingers and Eye Gaze

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Ómar I. Jóhannesson

2016-03-01

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

Habitat-specific foraging strategies in Australasian gannets

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Melanie R. Wells

2016-07-01

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

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.

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

African Journals Online (AJOL)

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

Interactions Increase Forager Availability and Activity in Harvester Ants.

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Evlyn Pless

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1981-12-01

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

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

Science.gov (United States)

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

2008-03-01

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

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.

Individual lifetime pollen and nectar foraging preferences in bumble bees

Science.gov (United States)

Hagbery, Jessica; Nieh, James C.

2012-10-01

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

The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage.

Science.gov (United States)

Lei, Yaogeng; Hannoufa, Abdelali; Yu, Peiqiang

2017-01-29

Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous degradation ratio of nitrogen to carbohydrate (N/CHO) in rumen. Genetic engineering approaches have been used to manipulate the expression of genes involved in important metabolic pathways for the purpose of improving the nutritive value, forage yield, and the ability to resist abiotic stress. Such gene modification could bring molecular structural changes in alfalfa that are detectable by advanced structural analytical techniques. These structural analyses have been employed in assessing alfalfa forage characteristics, allowing for rapid, convenient and cost-effective analysis of alfalfa forage quality. In this article, we review two major obstacles facing alfalfa utilization, namely poor protein utilization and relatively high lignin content, and highlight genetic studies that were performed to overcome these drawbacks, as well as to introduce other improvements to alfalfa quality. We also review the use of advanced molecular structural analysis in the assessment of alfalfa forage for its potential usage in quality selection in alfalfa breeding.

The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage

Energy Technology Data Exchange (ETDEWEB)

Lei, Yaogeng; Hannoufa, Abdelali; Yu, Peiqiang

2017-01-29

Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous degradation ratio of nitrogen to carbohydrate (N/CHO) in rumen. Genetic engineering approaches have been used to manipulate the expression of genes involved in important metabolic pathways for the purpose of improving the nutritive value, forage yield, and the ability to resist abiotic stress. Such gene modification could bring molecular structural changes in alfalfa that are detectable by advanced structural analytical techniques. These structural analyses have been employed in assessing alfalfa forage characteristics, allowing for rapid, convenient and cost-effective analysis of alfalfa forage quality. In this article, we review two major obstacles facing alfalfa utilization, namely poor protein utilization and relatively high lignin content, and highlight genetic studies that were performed to overcome these drawbacks, as well as to introduce other improvements to alfalfa quality. We also review the use of advanced molecular structural analysis in the assessment of alfalfa forage for its potential usage in quality selection in alfalfa breeding.

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

Science.gov (United States)

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

2016-09-01

Honey bees (Apis mellifera L.) show a large variation in foraging distances and use a broad range of plant species as pollen resources, even in regions with intensive agriculture. However, it is unknown how increasing areas of mass-flowering crops like oilseed rape (Brassica napus; OSR) or a decrease of seminatural habitats (SNH) change the temporal and spatial availability of pollen resources for honey bee colonies, and thus foraging distances and frequency in different habitat types. We studied pollen foraging of honey bee colonies in 16 agricultural landscapes with independent gradients of OSR and SNH area within 2 km and used waggle dances and digital geographic maps with major land cover types to reveal the distance and visited habitat type on a landscape level. Mean pollen foraging distance of 1347 decoded bee dances was 1015 m (± 26 m; SEM). In spring, increasing area of flowering OSR within 2 km reduced mean pollen foraging distances from 1324 m to only 435 m. In summer, increasing cover of SNH areas close to the colonies (within 200 m radius) reduced mean pollen foraging distances from 846 to 469 m. Frequency of pollen foragers per habitat type, measured as the number of dances per hour and hectare, was equally high for SNH, grassland, and OSR fields, but lower for other crops and forests. In landscapes with a small proportion of SNH a significantly higher density of pollen foragers on SNH was observed, indicating that pollen resources in such simple agricultural landscapes are more limited. Overall, we conclude that SNH and mass-flowering crops can reduce foraging distances of honey bee colonies at different scales and seasons with possible benefits for the performance of honey bee colonies. Further, mixed agricultural landscapes with a high proportion of SNH reduce foraging densities of honey bees in SNH and thus possible competition for pollen resources. © 2016 by the Ecological Society of America.

Agronomic and forage characteristics of Guazuma ulmifolia Lam.

OpenAIRE

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

2011-01-01

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

Foraging ecology of least terns and piping plovers nesting on Central Platte River sandpits and sandbars

Science.gov (United States)

Sherfy, Mark H.; Anteau, Michael J.; Shaffer, Terry L.; Sovada, Marsha A.; Stucker, Jennifer H.

2012-01-01

Federally listed least terns (Sternula antillarum) and piping plovers (Charadrius melodus) nest on riverine sandbars on many major midcontinent river systems. On the Central Platte River, availability of sandbar habitat is limited, and both species nest on excavated sandpits in the river's floodplain. However, the extent to which sandpit-nesting birds use riverine habitats for foraging is unknown. We evaluated use of foraging habitats by least terns and piping plovers by collecting data on movements, behavior, foraging habitat, and productivity. We radiomarked 16 piping plovers and 23 least terns in 2009-2010 and monitored their movements using a network of fixed telemetry dataloggers. Piping plovers were detected primarily by the datalogger located in their nesting sandpit, whereas least terns were more frequently detected on dataloggers outside of the nesting sandpit. Telemetry data and behavioral observations showed that least terns tended to concentrate at the Kearney Canal Diversion Gates, where forage fish were apparently readily available. Fish sampling data suggested that forage fish were more abundant in riverine than in sandpit habitats, and behavioral observations showed that least terns foraged more frequently in riverine than in sandpit habitats. Piping plovers tended to forage in wet substrates along sandpit shorelines, but also used dry substrates and sandpit interior habitats. The greater mobility of least terns makes a wider range of potential foraging habitats available during brood rearing, making them able to exploit concentrations of fish outside the nesting colony. Thus, our data suggest that different spatial scales should be considered in managing nesting and foraging habitat complexes for piping plovers and least terns.

Genetic Architecture of Natural Variation Underlying Adult Foraging Behavior That Is Essential for Survival of Drosophila melanogaster.

Science.gov (United States)

Lee, Yuh Chwen G; Yang, Qian; Chi, Wanhao; Turkson, Susie A; Du, Wei A; Kemkemer, Claus; Zeng, Zhao-Bang; Long, Manyuan; Zhuang, Xiaoxi

2017-05-01

Foraging behavior is critical for the fitness of individuals. However, the genetic basis of variation in foraging behavior and the evolutionary forces underlying such natural variation have rarely been investigated. We developed a systematic approach to assay the variation in survival rate in a foraging environment for adult flies derived from a wild Drosophila melanogaster population. Despite being such an essential trait, there is substantial variation of foraging behavior among D. melanogaster strains. Importantly, we provided the first evaluation of the potential caveats of using inbred Drosophila strains to perform genome-wide association studies on life-history traits, and concluded that inbreeding depression is unlikely a major contributor for the observed large variation in adult foraging behavior. We found that adult foraging behavior has a strong genetic component and, unlike larval foraging behavior, depends on multiple loci. Identified candidate genes are enriched in those with high expression in adult heads and, demonstrated by expression knock down assay, are involved in maintaining normal functions of the nervous system. Our study not only identified candidate genes for foraging behavior that is relevant to individual fitness, but also shed light on the initial stage underlying the evolution of the behavior. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

BEE FORAGE MAPPING BASED ON MULTISPECTRAL IMAGES LANDSAT

Directory of Open Access Journals (Sweden)

A. Moskalenko

2016-10-01

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

Best practices for assessing forage fish fisheries-seabird resource competition

Science.gov (United States)

Sydeman, William J.; Thompson, Sarah Ann; Anker-Nilssen, Tycho; Arimitsu, Mayumi L.; Bennison, Ashley; Bertrand, Sophie; Boersch-Supan, Philipp; Boyd, Charlotte; Bransome, Nicole C.; Crawford, Robert J.M.; Daunt, Francis; Furness, Robert W.; Gianuca, Dimas; Gladics, Amanda; Koehn, Laura; Lang, Jennifer W.; Loggerwell, Elizabeth; Morris, Taryn L.; Phillips, Elizabeth M.; Provencher, Jennifer; Punt, André E..; Saraux, Claire; Shannon, Lynne; Sherley, Richard B.; Simeone, Alejandro; Wanless, Ross M.; Wanless, Sarah; Zador, Stephani

2017-01-01

Worldwide, in recent years capture fisheries targeting lower-trophic level forage fish and euphausiid crustaceans have been substantial (∼20 million metric tons [MT] annually). Landings of forage species are projected to increase in the future, and this harvest may affect marine ecosystems and predator-prey interactions by removal or redistribution of biomass central to pelagic food webs. In particular, fisheries targeting forage fish and euphausiids may be in competition with seabirds, likely the most sensitive of marine vertebrates given limitations in their foraging abilities (ambit and gape size) and high metabolic rate, for food resources. Lately, apparent competition between fisheries and seabirds has led to numerous high-profile conflicts over interpretations, as well as the approaches that could and should be used to assess the magnitude and consequences of fisheries-seabird resource competition. In this paper, we review the methods used to date to study fisheries competition with seabirds, and present “best practices” for future resource competition assessments. Documenting current fisheries competition with seabirds generally involves addressing two major issues: 1) are fisheries causing localized prey depletion that is sufficient to affect the birds? (i.e., are fisheries limiting food resources?), and 2) how are fisheries-induced changes to forage stocks affecting seabird populations given the associated functional or numerical response relationships? Previous studies have been hampered by mismatches in the scale of fisheries, fish, and seabird data, and a lack of causal understanding due to confounding by climatic and other ecosystem factors (e.g., removal of predatory fish). Best practices for fisheries-seabird competition research should include i) clear articulation of hypotheses, ii) data collection (or summation) of fisheries, fish, and seabirds on matched spatio-temporal scales, and iii) integration of observational and experimental

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

Directory of Open Access Journals (Sweden)

Jolly Kabirizi

2013-12-01

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

Personality-dependent differences in problem-solving performance in a social context reflect foraging strategies.

Science.gov (United States)

Zandberg, Lies; Quinn, John L; Naguib, Marc; van Oers, Kees

2017-01-01

Individuals develop innovative behaviours to solve foraging challenges in the face of changing environmental conditions. Little is known about how individuals differ in their tendency to solve problems and in their subsequent use of this solving behaviour in social contexts. Here we investigated whether individual variation in problem-solving performance could be explained by differences in the likelihood of solving the task, or if they reflect differences in foraging strategy. We tested this by studying the use of a novel foraging skill in groups of great tits (Parus major), consisting of three naive individuals with different personality, and one knowledgeable tutor. We presented them with multiple, identical foraging devices over eight trials. Though birds of different personality type did not differ in solving latency; fast and slow explorers showed a steeper increase over time in their solving rate, compared to intermediate explorers. Despite equal solving potential, personality influenced the subsequent use of the skill, as well as the pay-off received from solving. Thus, variation in the tendency to solve the task reflected differences in foraging strategy among individuals linked to their personality. These results emphasize the importance of considering the social context to fully understand the implications of learning novel skills. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Directory of Open Access Journals (Sweden)

Marianna Chimienti

2014-09-01

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

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.

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

OpenAIRE

Kazuharu Ohashi; Alison Leslie; James D. Thomson

2013-01-01

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

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.

The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage

Directory of Open Access Journals (Sweden)

Yaogeng Lei

2017-01-01

Full Text Available Abstract: Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous degradation ratio of nitrogen to carbohydrate (N/CHO in rumen. Genetic engineering approaches have been used to manipulate the expression of genes involved in important metabolic pathways for the purpose of improving the nutritive value, forage yield, and the ability to resist abiotic stress. Such gene modification could bring molecular structural changes in alfalfa that are detectable by advanced structural analytical techniques. These structural analyses have been employed in assessing alfalfa forage characteristics, allowing for rapid, convenient and cost-effective analysis of alfalfa forage quality. In this article, we review two major obstacles facing alfalfa utilization, namely poor protein utilization and relatively high lignin content, and highlight genetic studies that were performed to overcome these drawbacks, as well as to introduce other improvements to alfalfa quality. We also review the use of advanced molecular structural analysis in the assessment of alfalfa forage for its potential usage in quality selection in alfalfa breeding.

Personality, foraging behavior and specialization: integrating behavioral and food web ecology at the individual level.

Science.gov (United States)

Toscano, Benjamin J; Gownaris, Natasha J; Heerhartz, Sarah M; Monaco, Cristián J

2016-09-01

Behavioral traits and diet were traditionally thought to be highly plastic within individuals. This view was espoused in the widespread use of optimality models, which broadly predict that individuals can modify behavioral traits and diet across ecological contexts to maximize fitness. Yet, research conducted over the past 15 years supports an alternative view; fundamental behavioral traits (e.g., activity level, exploration, sociability, boldness and aggressiveness) and diet often vary among individuals and this variation persists over time and across contexts. This phenomenon has been termed animal personality with regard to behavioral traits and individual specialization with regard to diet. While these aspects of individual-level phenotypic variation have been thus far studied in isolation, emerging evidence suggests that personality and individual specialization may covary, or even be causally related. Building on this work, we present the overarching hypothesis that animal personality can drive specialization through individual differences in various aspects of consumer foraging behavior. Specifically, we suggest pathways by which consumer personality traits influence foraging activity, risk-dependent foraging, roles in social foraging groups, spatial aspects of foraging and physiological drivers of foraging, which in turn can lead to consistent individual differences in food resource use. These pathways provide a basis for generating testable hypotheses directly linking animal personality to ecological dynamics, a major goal in contemporary behavioral ecology.

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

Science.gov (United States)

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

2007-07-01

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

Neural Mechanisms of Foraging

OpenAIRE

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

2012-01-01

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

Annual forage cropping-systems for midwestern ruminant livestock production

OpenAIRE

McMillan, John Ernest

2016-01-01

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

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

Directory of Open Access Journals (Sweden)

Katsunori Sunagawa

2016-02-01

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

Forage evaluation by analysis after

African Journals Online (AJOL)

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

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

Science.gov (United States)

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

2016-01-01

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

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

Directory of Open Access Journals (Sweden)

Mariana Lozada

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

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

Science.gov (United States)

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

2017-09-01

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

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…

Competition and facilitation between a native and a domestic herbivore: trade-offs between forage quantity and quality.

Science.gov (United States)

Augustine, David J; Springer, Tim L

2013-06-01

Potential competition between native and domestic herbivores is a major consideration influencing the management and conservation of native herbivores in rangeland ecosystems. In grasslands of the North American Great Plains, black-tailed prairie dogs (Cynomys ludovicianus) are widely viewed as competitors with cattle but are also important for biodiversity conservation due to their role in creating habitat for other native species. We examined spatiotemporal variation in prairie dog effects on growing-season forage quality and quantity using measurements from three colony complexes in Colorado and South Dakota and from a previous study of a fourth complex in Montana. At two complexes experiencing below-average precipitation, forage availability both on and off colonies was so low (12-54 g/m2) that daily forage intake rates of cattle were likely constrained by instantaneous intake rates and daily foraging time. Under these dry conditions, prairie dogs (1) substantially reduced forage availability, thus further limiting cattle daily intake rates, and (2) had either no or a small positive effect on forage digestibility. Under such conditions, prairie dogs are likely to compete with cattle in direct proportion to their abundance. For two complexes experiencing above-average precipitation, forage quantity on and off colonies (77-208 g/m2) was sufficient for daily forage intake of cattle to be limited by digestion rather than instantaneous forage intake. At one complex where prairie dogs enhanced forage digestibility and [N] while having no effect on forage quantity, prairie dogs are predicted to facilitate cattle mass gains regardless of prairie dog abundance. At the second complex where prairie dogs enhanced digestibility and [N] but reduced forage quantity, effects on cattle can vary from competition to facilitation depending on prairie dog abundance. Our findings show that the high spatiotemporal variation in vegetation dynamics characteristic of semiarid grasslands

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

Directory of Open Access Journals (Sweden)

Ruth J Sharples

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

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

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

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.

The regulation of ant colony foraging activity without spatial information.

Directory of Open Access Journals (Sweden)

Balaji Prabhakar

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

Is there an endogenous tidal foraging rhythm in marine iguanas?

Science.gov (United States)

Wikelski, M; Hau, M

1995-12-01

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

Experimental Evidence that Social Relationships Determine Individual Foraging Behavior

OpenAIRE

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

2015-01-01

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

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

NARCIS (Netherlands)

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

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

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

Science.gov (United States)

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

2011-01-01

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

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

Science.gov (United States)

Gende, Scott M.; Sigler, Michael F.

2006-02-01

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

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

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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.

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.

Risso's dolphins plan foraging dives.

Science.gov (United States)

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

2018-02-28

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

Intake and milk yield of Zebu cows fed Moringa forage ensiled with ...

African Journals Online (AJOL)

Poor nutrition of Zebu cattle grazing low quality native pastures is still a major constraint to milk production in Nigeria. High protein Moringa oleifera silage fed to these animals has potential to improve local milk production. In this study, moringa forage (MF) was ensiled with cassava peel (CSP) at 30, 50 and 70 % inclusion ...

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

Directory of Open Access Journals (Sweden)

Blanca Aurora Arce Barboza

2013-07-01

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

Increasing evidence that bats actively forage at wind turbines.

Science.gov (United States)

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

2017-01-01

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

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

Science.gov (United States)

Jha, Shalene; Kremen, Claire

2013-01-08

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

Information Foraging in Nuclear Power Plant Control Rooms

International Nuclear Information System (INIS)

Boring, R.L.

2011-01-01

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

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.

Improving the Yield and Nutritional Quality of Forage Crops

Directory of Open Access Journals (Sweden)

Nicola M. Capstaff

2018-04-01

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

Variation in daily flight activity and foraging patterns in colonies of uruçu - Melipona scutellaris Latreille (Apidae, Meliponini

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Leonardo Monteiro Pierrot

2003-12-01

Full Text Available The flight activities of five colonies of Melipona (Michmelia scutellaris Latreille, 1811 kept among mixed fruit crop plantations in within fragments of Atlantic Rainforest in Pernambuco, NE-Brazil was examined. The daily deployment of foragers to collect pollen, nectar, resin and mud was observed. The colonies performed between 2,640 and 14,250 flights per day. Variations in the number of total daily flights were similar between colonies on all observation days. Proportional allocation of foragers to the different resources also among colonies showed similar variation. More than 90% of the pollen collection flights were made early in the morning. Nectar was collected in similar proportional frequencies with a reduction in activity at noon. On a single day, was observed atypical intense pollen foraging during the afternoon by all colonies. This indicates a high plasticity in foraging behaviour and efficient recruitment to resources which are presented by mass flowering trees with synchronised big bang or multiple bang flowering. Resource availability of the surrounding vegetation, therefore, seems to be the major factor in defining the forager activities on a given day.

Utilization of Swamp Forages from South Kalimantan on Local Goat Performances

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T. Rostini

2014-04-01

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

The Conditions Favoring Between-Community Raiding in Chimpanzees, Bonobos, and Human Foragers.

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Pandit, Sagar A; Pradhan, Gauri R; Balashov, Hennadii; Van Schaik, Carel P

2016-06-01

Chimpanzees, bonobos, and human foragers share a fission-fusion social system and a mating system of joint male resource defense polygyny. Within-community skew in male strength varies among and within species. In this study, we extend a mathematical model of within-group male coalition formation among primates to derive the conditions for between-community conflicts in the form of raids. We show that the main factor affecting the presence of successful raiding is the likelihood of major discrepancies in party strength, which are set by party size distributions (and thus community size) and the skew in strength. This study confirms the functional similarities between the raiding of chimpanzees and human foragers, and it supports the "imbalance of power" hypothesis for raiding. However, it also proposes two amendments to this model. First, the absence of raiding in bonobos may be attributable more to potential female involvement in defense against raids, which increases the size of defensive coalitions. Second, the model attributes some of the raiding in humans to major contrasts in instantaneous fighting ability created by surprise raids on unarmed victims; it also draws attention to the distinction between minor raids and major raids that involve multiple bands of the same community.

Comparative Foraging Efficiency of Two Sympatric Jackals, Silver-Backed Jackals (Canis mesomelas and Golden Jackals (Canis aureus, in the Ngorongoro Crater, Tanzania

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S. E. Temu

2016-01-01

Full Text Available The foraging efficiency of two sympatric species of jackals, silver-backed jackals (Canis mesomelas and golden jackals (Canis aureus, was studied in the Ngorongoro crater from July 2014 through May 2015. The focal animal observation method was used and individuals of both species were followed as they foraged from morning to evening. Observations of individuals of both jackal species were made from a vehicle using binoculars and a spotting scope. Three major parameters were used for determination of foraging efficiency: distance travelled while foraging, time spent foraging, and amount of food secured in foraging period. The Mann–Whitney U test showed no significant difference (P>0.05 in distance travelled per unit time of foraging between the two species in the dry and wet seasons, respectively. Golden jackals secured a significantly higher amount of food than the silver-backed jackals in the wet season (Mann–Whitney U test, P<0.05, U=1035.4. Hunting of prey larger than Thomson’s gazelle (Eudorcas thomsonii fawns was not common. Both species mainly fed on smaller prey such as invertebrates and rodents and scavenged opportunistically. Efficient foraging is crucial for both jackal species especially during their breeding season when they are provisioning dependent pups.

Urban gardens promote bee foraging over natural habitats and plantations.

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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.

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

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Ken Tan

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

7 CFR 457.117 - Forage production crop insurance provisions.

Science.gov (United States)

2010-01-01

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

Genetic options for improving fodder yield and quality in forage sorghum

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C. Aruna

2015-01-01

Full Text Available Improving yield and quality of fodder from forage sorghum is important, especially in the semi-arid tropics, where sorghum is a major source of fodder. The aim of this work was to understand the genetic basis of fodder yield and quality traits, and character associations, and to estimate combining ability of the parents. The experiment was carried out during 2 successive rainy seasons using 10 parents crossed in a half-diallel design. Significant differences among the genotypes for fodder yield, quality and cell wall constituents were observed. Important quality traits, crude protein and digestibility (IVOMD, were not correlated with fodder yield, indicating the potential to improve yield and quality simultaneously in forage sorghum. General combining ability and specific combining ability variances showed that, for almost all characters, both additive and non-additive gene effects were important, with a predominance of non-additive effects. Parental lines SEVS4, HC308 and UPMC503 were good general combiners for yield and quality. The brown midrib lines, EC582508 and EC582510, were good general combiners for low lignin and high IVOMD. Strategies for improving forage sorghum to suit animal and biofuel industries are discussed.Keywords: Digestibility, crude protein, ADL, diallel analysis, gene effects.DOI: 10.17138/TGFT(349-58

GPS tracking devices reveal foraging strategies of black-legged kittiwakes

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

2010-01-01

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

Developing Cyber Foraging Applications for Portable Devices

DEFF Research Database (Denmark)

Kristensen, Mads Darø; Bouvin, Niels Olof

2008-01-01

This paper presents the Locusts cyber foraging framework. Cyber foraging is the opportunistic use of computing resources available in the nearby environment, and using such resources thus fall into the category of distributed computing. Furthermore, for the resources to be used efficiently, paral...

Forage: a sensitive indicator of airborne radioactivity

International Nuclear Information System (INIS)

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

1981-01-01

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

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

African Journals Online (AJOL)

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

Projected poleward shift of king penguins' (Aptenodytes patagonicus) foraging range at the Crozet Islands, southern Indian Ocean.

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Péron, Clara; Weimerskirch, Henri; Bost, Charles-André

2012-07-07

Seabird populations of the Southern Ocean have been responding to climate change for the last three decades and demographic models suggest that projected warming will cause dramatic population changes over the next century. Shift in species distribution is likely to be one of the major possible adaptations to changing environmental conditions. Habitat models based on a unique long-term tracking dataset of king penguin (Aptenodytes patagonicus) breeding on the Crozet Islands (southern Indian Ocean) revealed that despite a significant influence of primary productivity and mesoscale activity, sea surface temperature consistently drove penguins' foraging distribution. According to climate models of the Intergovernmental Panel on Climate Change (IPCC), the projected warming of surface waters would lead to a gradual southward shift of the more profitable foraging zones, ranging from 25 km per decade for the B1 IPCC scenario to 40 km per decade for the A1B and A2 scenarios. As a consequence, distances travelled by incubating and brooding birds to reach optimal foraging zones associated with the polar front would double by 2100. Such a shift is far beyond the usual foraging range of king penguins breeding and would negatively affect the Crozet population on the long term, unless penguins develop alternative foraging strategies.

7 CFR 407.13 - Group risk plan for forage.

Science.gov (United States)

2010-01-01

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

Foraging niche segregation in Malaysian babblers (Family: Timaliidae.

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Mohammad Saiful Mansor

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

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

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Mansor, Mohammad Saiful; Ramli, Rosli

2017-01-01

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

Foraging niche segregation in Malaysian babblers (Family: Timaliidae)

Science.gov (United States)

Mansor, Mohammad Saiful; Ramli, Rosli

2017-01-01

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

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

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

2017-03-01

The use of locally produced forage (LPF) in cattle production has economic and environmental advantages over imported forage. The objective of this study was to characterize the nutritional value of LPF commonly used in Korea. Differences in ruminal fermentation characteristics were also examined for the LPF species commonly produced from two major production regions: Chungcheong and Jeolla. Ten LPF (five from each of the two regions) and six of the most widely used imported forages originating from North America were obtained at least three times throughout a year. Each forage species was pooled and analyzed for nutrient content using detailed chemical analysis. Ruminal fermentation characteristics were also determined by in vitro anaerobic incubations using strained rumen fluid for 0, 3, 6, 12, 24, and 48 h. At each incubation time, total gas, pH, ammonia, volatile fatty acid (VFA) concentrations, and neutral detergent fiber digestibility were measured. By fitting an exponential model, gas production kinetics were obtained. Significant differences were found in the non-fiber carbohydrate (NFC) content among the forage species and the regions (pruminal fermentation of LPF between the two regions and interactions between regions and forage species were also significant (pruminal fermentation was lower in the forages from Chungcheong than from Jeolla (p<0.01), and total VFA concentration was higher in Chungcheong than in Jeolla (p = 0.05). This implies that fermentation was more active with the forages from Chungcheong than from Jeolla. Analysis of gas production profiles showed the rate of fermentation differed among forage species (p<0.05). The results of the present study showed that the nutritional values of some LPF (i.e., corn silage and Italian ryegrass) are comparable to those of imported forages widely used in Korea. This study also indicated that the nutritional value of LPF differs by origin, as well as by forage species. Detailed analyses of nutrient

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

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Elliott, Susan E

2009-06-01

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

SILAGE QUALITY OF CORN AND SORGHUM ADDED WITH FORAGE PEANUTS

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WALKÍRIA GUIMARÃES CARVALHO

2016-01-01

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

Predation risk and optimal foraging trade-off in the demography and spacing of the George River Herd, 1958 to 1993

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Arthur T. Bergerud

2003-04-01

Full Text Available The behavior options of feeding animals lie on a continuum between energy maximization and minimization of predation risk. We studied the distribution, mobility, and energy budgets of the George River herd, Ungava from 1974 to 1993. We arranged the annual cycle into 6 phases where we argue that the importance between the priorities of optimal foraging and predation risk change between periods. At calving, risk is more important than foraging for females but males take more risk to optimally forage. During the mosquito season, insect avoidance takes priority over risk and for¬aging. Optimal foraging takes precedent over risk in the late summer and fall and it is at this time that the herd expanded its range relative to numbers and forage abundance. In the winter (December to mid-March animals sought restricted localized ranges with low snow cover to reduce predation risk. The spring migration of females may have increased risk during the interval the females were moving back to the tundra to give birth to their neonates on the low risk calv¬ing ground. In May, females sought early greens near treeline, which may have increased risk in order to provide maximum nutrition to their fetuses in the last weeks of pregnancy. The ancestors of the George River Herd during the Pleistocene, 18 000 yr. BP may have reduced predation risk by spacing-out in the Appalachian Mountains, removed from the major specie of the megafauna in the lowlands. With global warming, it is argued the major problem for caribou will be increased wolf predation rather than changing forage and nutritional regimes. It is essential that First Nation residents of the North maintain their option to manage wolf numbers if excessive predation in the future adversely affects the migratory herds of the Northwest Territories and Ungava.

Assessing the Effects of Grassland Management on Forage Production and Environmental Quality to Identify Paths to Ecological Intensification in Mountain Grasslands.

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Loucougaray, Grégory; Dobremez, Laurent; Gos, Pierre; Pauthenet, Yves; Nettier, Baptiste; Lavorel, Sandra

2015-11-01

Ecological intensification in grasslands can be regarded as a process for increasing forage production while maintaining high levels of ecosystem functions and biodiversity. In the mountain Vercors massif, where dairy cattle farming is the main component of agriculture, how to achieve forage autonomy at farm level while sustaining environmental quality for tourism and local dairy products has recently stimulated local debate. As specific management is one of the main drivers of ecosystem functioning, we assessed the response of forage production and environmental quality at grassland scale across a wide range of management practices. We aimed to determine which components of management can be harnessed to better match forage production and environmental quality. We sampled the vegetation of 51 grasslands stratified across 13 grassland types. We assessed each grassland for agronomic and environmental properties, measuring forage production, forage quality, and indices based on the abundance of particular plant species such as timing flexibility, apiarian potential, and aromatic plants. Our results revealed an expected trade-off between forage production and environmental quality, notably by stressing the contrasts between sown and permanent grasslands. However, strong within-type variability in both production and environmental quality as well as in flexibility of timing of use suggests possible ways to improve this trade-off at grassland and farm scales. As achieving forage autonomy relies on increasing both forage production and grassland resilience, our results highlight the critical role of the ratio between sown and permanent grasslands as a major path for ecological intensification in mountain grasslands.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

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

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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.

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

Science.gov (United States)

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

2009-02-01

The effects of forage type and forage:concentrate ratio (F:C) on apparent nutrient digestibility, ruminal fermentation, and microbial growth were investigated in goats. A comparison between liquid (LAB) and solid (SAB)-associated bacteria to estimate microbial N flow (MNF) from urinary purine derivative excretion was also examined. Treatments were a 2 x 2 factorial arrangement of forage type (grass hay vs. alfalfa hay) and high vs. low F:C (70:30 and 30:70, respectively). Four ruminally cannulated goats were fed, at maintenance intake, 4 experimental diets according to a 4 x 4 Latin square design. High-concentrate diets resulted in greater (P 0.05) when diets included alfalfa hay. Total protozoa numbers and holotricha proportion were greater and less (P forage used. The MNF measured in goats fed different diets was influenced by the bacterial pellet (LAB or SAB). In addition, the purine bases:N ratio values found were different from those reported in the literature, which underlines the need for these variables to be analyzed directly in pellets isolated from specific animals and experimental conditions.

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

OpenAIRE

Klein, Barrett; Seeley, Thomas D.

2011-01-01

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

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

International Nuclear Information System (INIS)

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

1999-01-01

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

Experimental Evidence that Social Relationships Determine Individual Foraging Behavior.

Science.gov (United States)

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

2015-12-07

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

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...

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.

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

Directory of Open Access Journals (Sweden)

Wenchao Yang

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

Comparative Sucrose Responsiveness in Apis mellifera and A. cerana Foragers

Science.gov (United States)

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

2013-01-01

In the European honey bee, Apis mellifera, pollen foragers have a higher sucrose responsiveness than nectar foragers when tested using a proboscis extension response (PER) assay. In addition, Africanized honey bees have a higher sucrose responsiveness than European honey bees. Based on the biology of the Eastern honey bee, A. cerana, we hypothesized that A. cerana should also have a higher responsiveness to sucrose than A. mellifera. To test this hypothesis, we compared the sucrose thresholds of pollen foragers and nectar foragers in both A. cerana and A. mellifera in Fujian Province, China. Pollen foragers were more responsive to sucrose than nectar foragers in both species, consistent with previous studies. However, contrary to our hypothesis, A. mellifera was more responsive than A. cerana. We also demonstrated that this higher sucrose responsiveness in A. mellifera was not due to differences in the colony environment by co-fostering two species of bees in the same mixed-species colonies. Because A. mellifera foragers were more responsive to sucrose, we predicted that their nectar foragers should bring in less concentrated nectar compared to that of A. cerana. However, we found no differences between the two species. We conclude that A. cerana shows a different pattern in sucrose responsiveness from that of Africanized bees. There may be other mechanisms that enable A. cerana to perform well in areas with sparse nectar resources. PMID:24194958

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.

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

Science.gov (United States)

Pope, Nathaniel S; Jha, Shalene

2018-01-01

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

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

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.

Nutrient balance affects foraging behaviour of a trap-building predator

DEFF Research Database (Denmark)

Mayntz, David; Toft, Søren; Vollrath, Fritz

2009-01-01

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

Climate-driven Sympatry does not Lead to Foraging Competition Between Adélie and Gentoo Penguins

Science.gov (United States)

Cimino, M. A.; Moline, M. A.; Fraser, W.; Patterson-Fraser, D.; Oliver, M. J.

2016-02-01

Climate-driven sympatry may lead to competition for food resources between species, population shifts and changes in ecosystem structure. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. At Palmer Station, we tested for foraging competition between these species by comparing their prey, Antarctic krill, distributions and penguin foraging behaviors on fine scales. To study these predator-prey dynamics, we simultaneously deployed penguin satellite transmitters, and a REMUS autonomous underwater vehicle that acoustically detected krill aggregations and measured physical and biological properties of the water column. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguin. In the upper 100 m of the water column, the distribution of krill aggregations were mainly associated with CHL and light, suggesting that krill selected for habitats that balance the need to consume food and avoid predation. Adélie and gentoo penguins mainly had spatially segregated foraging areas but in areas of overlap, gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion. Contrary to a recent theory, which suggests that increased competition for krill is the major driver of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories.

Information Foraging Theory: A Framework for Intelligence Analysis

Science.gov (United States)

2014-11-01

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

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

Directory of Open Access Journals (Sweden)

Somchaya Liemhetcharat

2015-09-01

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

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.

Forage yield and nutritive value of Elephant grass, Italian ryegrass and spontaneous growing species mixed with forage peanut or red clover

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Michelle Schalemberg Diehl

2014-10-01

Full Text Available The objective of this research was to evaluate of three grazing systems (GS with elephant grass (EG, Italian ryegrass (IR + spontaneous growing species (SGS; EG + IR + SGS + forage peanut (FP; and EG + IR + SGS + red clover (RC, during the winter and summer periods in rotational grazing with dairy cattle. Experimental design was completely randomized with three treatments, two replicates with repeated measures. Lactating Holstein cows receiving 1% BW-daily feed supplement with concentrate were used in the evaluation. Eight grazing cycles were performed during the experimental period. The values of pre forage mass and stocking rate were 2.52, 2.60 and 2.99 t ha-1 and 2.64, 2.77 and 3.14 animal unit ha-1, respectively for GS. Samples of forage were collected by hand-plucking technique to analyze the crude protein (CP, neutral detergent fiber (NDF, in situ dry matter digestibility (ISDMD, in situ organic matter digestibility (ISOMD of forage present between rows of elephant grass, in the rows of elephant grass and the legumes. Higher value of CP, ISOMD and lower of NDF were observed for the grazing systems mixed with legumes forage.

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

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Michael Peters

2013-12-01

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

Trade-Off between Foraging Activity and Infestation by Nest Parasites in the Primitively Eusocial Bee Halictus scabiosae

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Andrea Lienhard

2010-01-01

Full Text Available Diurnal activities of Halictus scabiosae bees and their nest parasites (major bee-flies, cuckoo wasps, ichneumon wasps, Sphecodes bees, and velvet ants were investigated at a study site with 159 nests in Eastern Austria. Foraging activity correlated with ambient temperature only before midday and decreased in the afternoon. The activity of nest-infesting parasites increased during the day and correlated with ambient temperature. The match factor fm between the ratios of the foraging activities of H. scabiosae and the ratios of aspects of morning temperature was assessed on three consecutive days with different weather. The activity patterns of halictine bees and their nest parasites differed: the parasites exhibited only small time windows in which their activities were synchronised with those of their hosts. The bees exhibited an anticyclic behaviour and collected food in times of low parasite pressure and decreased foraging activity when parasite pressure increased.

Forage based animal production systems and sustainability, an invited keynote

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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

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...

Floral odor learning within the hive affects honeybees' foraging decisions

Science.gov (United States)

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

2007-03-01

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

Is Bumblebee Foraging Efficiency Mediated by Morphological Correspondence to Flowers?

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Ikumi Dohzono

2011-01-01

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

Corn in consortium with forages

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Cássia Maria de Paula Garcia

2013-12-01

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

Physiology, phenology and behavioural strategies of forage fish

DEFF Research Database (Denmark)

Frisk, Christina

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

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...

Food and foraging preferences of three pteropodid bats in southern India

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M.R Sudhakaran

2012-01-01

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

The ecological economics of kleptoparasitism: pay-offs from self-foraging versus kleptoparasitism.

Science.gov (United States)

Flower, Tom P; Child, Matthew F; Ridley, Amanda R

2013-01-01

Animals commonly steal food from other species, termed interspecific kleptoparasitism, but why animals engage in kleptoparasitism compared with alternate foraging tactics, and under what circumstances they do so, is not fully understood. Determining what specific benefits animals gain from kleptoparasitism could provide valuable insight into its evolution. Here, we investigate the benefits of kleptoparasitism for a population of individually recognizable and free-living fork-tailed drongos (Dicrurus adsimilis) in the southern Kalahari Desert. Drongos engaged in two foraging behaviours: self-foraging for small insects or following other species which they kleptoparasitized for larger terrestrial prey that they could not capture themselves. Kleptoparasitism consequently enabled drongos to exploit a new foraging niche. Kleptoparasitism benefitted drongos most in the morning and on colder days because at these times pay-offs from kleptoparasitism remained stable, while those from self-foraging declined. However, drongos engaged in kleptoparasitism less than expected given the overall high (but more variable) pay-offs from this behaviour, suggesting that kleptoparasitism is a risky foraging tactic and may incur additional foraging costs compared with self-foraging. This is the first study to comprehensively investigate the benefits of facultatively engaging in kleptoparasitism, demonstrating that animals may switch to kleptoparasitism to exploit a new foraging niche when pay-offs exceed those from alternate foraging behaviours. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

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

African Journals Online (AJOL)

Novin

2012-07-17

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

The forager oral tradition and the evolution of prolonged juvenility.

Science.gov (United States)

Scalise Sugiyama, Michelle

2011-01-01

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

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.

Scavenger: Transparent Development of Efficient Cyber Foraging Applications

DEFF Research Database (Denmark)

Kristensen, Mads Darø

2010-01-01

delivering efficient, mobile use of remote computing resources through the use of a custom built mobile code execution environment and a new dual-profiling scheduler. One of the main difficulties within cyber foraging is that it is very challenging for application programmers to develop cyber foraging...

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

Science.gov (United States)

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

Foraging behavior analysis of swarm robotics system

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Sakthivelmurugan E.

2018-01-01

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

The Synergistic Effects of Almond Protection Fungicides on Honey Bee (Hymenoptera: Apidae) Forager Survival.

Science.gov (United States)

Fisher, Adrian; Coleman, Chet; Hoffmann, Clint; Fritz, Brad; Rangel, Juliana

2017-06-01

The honey bee (Apis mellifera L.) contributes ∼$17 billion annually to the United States economy, primarily by pollinating major agricultural crops including almond, which is completely dependent on honey bee pollination for nut set. Almond growers face constant challenges to crop productivity owing to pests and pathogens, which are often controlled with a multitude of agrochemicals. For example, fungicides are often applied in combination with other products to control fungal pathogens during almond bloom. However, the effects of fungicides on honey bee health have been so far understudied. To assess the effects of some of the top fungicides used during the 2012 California almond bloom on honey bee forager mortality, we collected foragers from a local apiary and exposed them to fungicides (alone and in various combinations) at the label dose, or at doses ranging from 0.25 to 2 times the label dose rate. These fungicides were Iprodione 2SE Select, Pristine, and Quadris. We utilized a wind tunnel and atomizer set up with a wind speed of 2.9 m/s to simulate field-relevant exposure of honey bees to these agrochemicals during aerial application in almond fields. Groups of 40-50 foragers exposed to either untreated controls or fungicide-laden treatments were monitored daily over a 10-d period. Our results showed a significant decrease in forager survival resulting from exposure to simulated tank mixes of Iprodione 2SE Select, as well as synergistic detrimental effects of Iprodione 2SE Select in combination with Pristine and Quadris on forager survival. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Nutritional Characteristics of Forage Grown in South of Benin

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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.

Forage herbs improve mineral composition of grassland herbage

DEFF Research Database (Denmark)

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

2011-01-01

there is limited information about mineral concentrations in forage herbs. To determine whether herbs have greater macro- and micromineral concentrations than forage legumes and grasses, we conducted a 2-year experiment on a loamy-sand site in Denmark sown with a multi-species mixture comprised of three functional...

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

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Neeltje J Boogert

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

A new approach to study of seabird-fishery overlap: Connecting chick feeding with parental foraging and overlap with fishing vessels

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Junichi Sugishita

2015-07-01

Full Text Available Incidental fisheries bycatch is recognised as a major threat to albatross populations worldwide. However, fishery discards and offal produced in large quantities might benefit some scavenging seabirds. Here, we demonstrate an integrated approach to better understand the ecological ramifications of fine-scale overlap between seabirds and fisheries. As a case study, we examined whether foraging in association with a fishing vessel is advantageous for chick provisioning in terms of quantity of food delivered to chicks, in northern royal albatross (Diomedea sanfordi at Taiaroa Head, New Zealand. Fine-scale overlap between albatrosses and vessels was quantified by integrating GPS tracking and Vessel Monitoring Systems (VMS. Meal size delivered to chicks was measured using custom-designed nest balances, and monitoring of attendance of adults fitted with radio transmitters was used in conjunction with time-lapse photography at the nest allowed us to allocate each feeding event to a specific parent. The combination of these techniques enabled comparison of meal sizes delivered to chicks with parental foraging trip durations with or without fishing vessels association. A total of 45 foraging trips and associated chick feeding events were monitored during the chick-rearing period in 2012. Differences in the meal size and foraging trip duration relative to foraging overlap with fisheries were examined using a linear mixed-effect model, adjusted for chick age. Our results, based on three birds, suggest that foraging in association with vessels does not confer an advantage for chick feeding for this population that demonstrated low rates of overlap while foraging. The integrated research design presented can be applied to other seabird species that are susceptible to bycatch, and offers a valuable approach to evaluate habitat quality by linking habitat use and foraging success in terms of total amount of food delivered to offspring.

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

Directory of Open Access Journals (Sweden)

LAVINIA MOISE

2007-05-01

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

Comparative Foraging Efficiency of Two Sympatric Jackals, Silver-Backed Jackals (Canis mesomelas) and Golden Jackals (Canis aureus), in the Ngorongoro Crater, Tanzania

OpenAIRE

Temu, S. E.; Nahonyo, C. L.; Moehlman, P. D.

2016-01-01

The foraging efficiency of two sympatric species of jackals, silver-backed jackals (Canis mesomelas) and golden jackals (Canis aureus), was studied in the Ngorongoro crater from July 2014 through May 2015. The focal animal observation method was used and individuals of both species were followed as they foraged from morning to evening. Observations of individuals of both jackal species were made from a vehicle using binoculars and a spotting scope. Three major parameters were used for determi...

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

Science.gov (United States)

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

2018-04-01

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

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

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

Science.gov (United States)

Wcislo, William T; Tierney, Simon M

2009-02-01

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

Recent developments in forage evaluation with special reference to practical applications

Directory of Open Access Journals (Sweden)

P. HUHTANEN

2008-12-01

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

Has eutrophication promoted forage fish production in the Baltic Sea?

DEFF Research Database (Denmark)

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

2016-01-01

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

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.

Does supplemental feeding affect behaviour and foraging of ...

African Journals Online (AJOL)

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

Effects of forage source and forage particle size as a free-choice provision on growth performance, rumen fermentation, and behavior of dairy calves fed texturized starters.

Science.gov (United States)

Omidi-Mirzaei, H; Azarfar, A; Mirzaei, M; Kiani, A; Ghaffari, M H

2018-05-01

We investigated the interactive effects of forage source and forage particle size (PS) as a free-choice provision on growth performance, rumen fermentation, and behavior of dairy calves fed texturized starters. Forty-eight Holstein calves (42 ± 3 kg of body weight) were randomly assigned (n = 12 calves per treatment) in a 2 × 2 factorial arrangement of treatments with the factors of forage source [alfalfa hay (AH) and wheat straw (WS)] and forage PS [(AH: medium = 1.96 mm or long = 3.93 mm) and (WS: medium = 2.03 mm or long = 4.10 mm), as geometric mean diameters]. The treatments were (1) AH with medium PS (AH-MPS), (2) AH with long PS (AH-LPS), (3) WS with medium PS (WS-MPS), and (4) WS with long PS (WS-LPS). Regardless of forage PS, the preweaning starter intake, dry matter intake, metabolizable energy intake, weaning body weight, and forage intake were greater for AH calves than WS calves. Average daily gain, average daily gain/metabolizable energy intake, feed efficiency, and final body weight of the calves did not differ among groups. An interaction of forage source and forage PS influenced acetate, propionate, and acetate-to-propionate ratio in the rumen on d 35, with the greatest acetate proportion and acetate-to-propionate ratio, but the least propionate proportion for AH-MPS calves than the other calves. The total volatile fatty acid concentration and the rumen proportions of propionate (d 70), butyrate (d 35), and valerate (d 35) were greater in AH-MPS calves than in AH-LPS calves. Calves fed AH had greater total volatile fatty acid concentration (d 35 and 70) and propionate proportion (d 70), but lesser ruminal proportions of butyrate (d 35 and 70), valerate (d 35 and 70), and acetate-to-propionate ratio (d 70) compared with calves fed WS. The ruminal valerate proportion (d 70) was greatest in WS-MPS calves than the other calves. An interaction of forage source and forage PS influenced preweaning standing time and starter eating time, with the least

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).

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

Science.gov (United States)

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

2001-01-01

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

Dive characteristics can predict foraging success in Australian fur seals (Arctocephalus pusillus doriferus as validated by animal-borne video

Directory of Open Access Journals (Sweden)

Beth L. Volpov

2016-03-01

Full Text Available Dive characteristics and dive shape are often used to infer foraging success in pinnipeds. However, these inferences have not been directly validated in the field with video, and it remains unclear if this method can be applied to benthic foraging animals. This study assessed the ability of dive characteristics from time-depth recorders (TDR to predict attempted prey capture events (APC that were directly observed on animal-borne video in Australian fur seals (Arctocephalus pusillus doriferus, n=11. The most parsimonious model predicting the probability of a dive with ≥1 APC on video included only descent rate as a predictor variable. The majority (94% of the 389 total APC were successful, and the majority of the dives (68% contained at least one successful APC. The best model predicting these successful dives included descent rate as a predictor. Comparisons of the TDR model predictions to video yielded a maximum accuracy of 77.5% in classifying dives as either APC or non-APC or 77.1% in classifying dives as successful verses unsuccessful. Foraging intensity, measured as either total APC per dive or total successful APC per dive, was best predicted by bottom duration and ascent rate. The accuracy in predicting total APC per dive varied based on the number of APC per dive with maximum accuracy occurring at 1 APC for both total (54% and only successful APC (52%. Results from this study linking verified foraging dives to dive characteristics potentially opens the door to decades of historical TDR datasets across several otariid species.

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.

Optimal search behavior and classic foraging theory

International Nuclear Information System (INIS)

Bartumeus, F; Catalan, J

2009-01-01

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

Morphological responses of forage sorghums to salinity and ...

African Journals Online (AJOL)

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

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.

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

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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.

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

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

2008-01-01

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

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

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

2013-01-01

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

King eider foraging effort during the pre-breeding period in Alaska

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Oppel, Steffen; Powell, Abby N.; Butler, Malcolm G.

2011-01-01

For reproduction, many arctic-nesting migratory birds rely on nutrients obtained on the breeding grounds, so they devote sufficient time to foraging immediately prior to nesting. However, little is known about the increase in foraging effort necessary to meet the energetic requirements of reproduction. In early June 2006 and 2008, we quantified the proportion of time spent foraging before breeding by a large sea duck, the King Eider (Somateria spectabilis), on its breeding grounds in northern Alaska. During >235 hours of behavioral observations, both male and female King Eiders spent >50% of the day loafing (resting, sleeping, comfort behavior, or being alert). Females foraged on average 30% of the time (mean 7.2 hr day-1,95% CI 6.0-8.4 hr day-1), three times as much as males (9%; 2.3 hr day-1, 95% CI 1.5–2.8 hr day-1). The most common prey in ponds where the eiders foraged were chironomid larvae and worms ranging in length from 1 to 30 mm. If the King Eider's daily energy expenditure on its breeding grounds is similar to values published for related species, it would need to ingest only 0.2–0.6 g dry mass of invertebrates per minute of foraging to meet its energetic requirements. Males did not lose body mass before breeding, and we assume that their foraging effort was sufficient for energy balance. Therefore, female King Eiders appear to triple their foraging effort over maintenance requirements to meet the energetic challenges of egg formation.

Determination of Tropical Forage Preferences Using Two Offering Methods in Rabbits

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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.

Foraging for brain stimulation: toward a neurobiology of computation.

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Gallistel, C R

1994-01-01

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

Foraging in corallivorous butterflyfish varies with wave exposure

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

2014-06-01

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

Videography reveals in-water behavior of loggerhead turtles (Caretta caretta at a foraging ground

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Samir Harshad Patel

2016-12-01

Full Text Available Assessing sea turtle behavior at the foraging grounds has been primarily limited to the interpretation of remotely-sensed data. As a result, there is a general lack of detailed understanding regarding the habitat use of sea turtles during a phase that accounts for a majority of their lives. Thus, this study aimed to fill these data gaps by providing detailed information about the feeding habits, prey availability, buoyancy control and water column usage by 73 loggerhead turtles across 45.7 hours of video footage obtained from a remotely operated vehicle (ROV from 2008 – 2014. We developed an ethogram to account for 27 potential environmental and behavioral parameters. Turtles were filmed through the entire water column and we quantified the frequency of behaviors such as flipper beats, breaths, defecations, feedings and reactions to the ROV. We used the ROV’s depth sensor and visible cues (i.e. water surface or benthic zone in view to distinguish depth zones and assess the turtles’ use of the water column. We also quantified interactions with sympatric biota, including potential gelatinous and non-gelatinous prey species, fish (including sharks, marine mammals and other sea turtles. We discovered that turtles tended to remain within the near surface and surface zones of the water column through the majority of the footage. During benthic dives, turtles consistently exhibited negative buoyancy and some turtles exhibited a dichotomous foraging behavior, first foraging within the water column, then diving to the benthic environment. Videography allowed us to combine behavioral observations and habitat features that cannot be captured by traditional telemetry methods, resulting in a broader understanding of loggerheads’ ecological role in the U.S. Mid-Atlantic.

Skill ontogeny among Tsimane forager-horticulturalists.

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

2015-09-01

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

Visual field shape and foraging ecology in diurnal raptors.

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

2018-05-18

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

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

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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

Cognitive plasticity in foraging Vespula germanica wasps.

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D'Adamo, Paola; Lozada, Mariana

2011-01-01

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

The dynamics of foraging trails in the tropical arboreal ant Cephalotes goniodontus.

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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.

Parasitized honey bees are less likely to forage and carry less pollen.

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Lach, Lori; Kratz, Madlen; Baer, Boris

2015-09-01

Research into loss of pollination capacity has focused primarily on documenting pollinator declines and their causes with comparatively little attention paid to how stressors may affect pollinating behavior of surviving pollinators. The European honey bee, Apis mellifera is one of the world's most important generalist pollinators, and Nosema apis is a widespread microsporidian gut parasite of adult A. mellifera. We individually fed 960 newly eclosed A. mellifera workers either a sucrose solution or 400 N. apis spores in a sucrose solution and tagged them with a unique radio frequency identification (RFID) tag to monitor their foraging behavior. We found spore-fed bees were less likely to forage than those fed sugar only. Those that did forage started foraging when they were older and stopped foraging when they were younger than bees fed sugar only. However, inoculated and non-inoculated bees did not significantly differ in the number of foraging trips taken per day, the total hours foraged over their lifetime, or homing ability. Inoculated returning foragers were 4.3 times less likely to be carrying available pollen than non-inoculated returning foragers and the number of pollen grains carried was negatively correlated with the number of N. apis spores. In an arena of artificial flowers, inoculated bees had a tendency (p=0.061) to choose sugar flowers over pollen flowers, compared to non-inoculated bees which visited pollen and sugar flowers equally. These results demonstrate that even a relatively low dose of a widespread disease of A. mellifera may adversely affect bees' ability to pollinate. Copyright © 2015 Elsevier Inc. All rights reserved.

The dynamics of foraging trails in the tropical arboreal ant Cephalotes goniodontus.

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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.

Fine-scale foraging ecology of leatherback turtles

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Bryan P Wallace

2015-02-01

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

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

African Journals Online (AJOL)

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

Optimal Foraging for Multiple Resources in Several Food Species

NARCIS (Netherlands)

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

2009-01-01

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

Optimal foraging for multiple resources in several food species

NARCIS (Netherlands)

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

2009-01-01

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

A properly adjusted forage harvester can save time and money

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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....

Red-cockaded woodpecker male/female foraging differences in young forest stands.

Energy Technology Data Exchange (ETDEWEB)

Franzreb, Kathleen, E.

2010-07-01

ABSTRACT The Red-cockaded Woodpecker (Picoides borealis) is an endangered species endemic to pine (Pinus spp.) forests of the southeastern United States. I examined Red-cockaded Woodpecker foraging behavior to learn if there were male/female differences at the Savannah River Site, South Carolina. The study was conducted in largely young forest stands (,50 years of age) in contrast to earlier foraging behavior studies that focused on more mature forest. The Redcockaded Woodpecker at the Savannah River site is intensively managed including monitoring, translocation, and installation of artificial cavity inserts for roosting and nesting. Over a 3-year period, 6,407 foraging observations covering seven woodpecker family groups were recorded during all seasons of the year and all times of day. The most striking differences occurred in foraging method (males usually scaled [45% of observations] and females mostly probed [47%]),substrate used (females had a stronger preference [93%] for the trunk than males [79%]), and foraging height from the ground (mean 6 SE foraging height was higher for males [11.1 6 0.5 m] than females [9.8 6 0.5 m]). Niche overlap between males and females was lowest for substrate (85.6%) and foraging height (87.8%), and highest for tree species (99.0%), tree condition (98.3%), and tree height (96.4%). Both males and females preferred to forage in older, large pine trees. The habitat available at the Savannah River Site was considerably younger than at most other locations, but the pattern of male/female habitat partitioning observed was similar to that documented elsewhere within the range attesting to the species’ ability to adjust behaviorally.

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

OpenAIRE

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

2012-01-01

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

Impact of Different Forms of Environmental Enrichment on Foraging and Activity Levels in Gorillas (Gorilla gorilla gorilla

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Kristie Charmoy

2015-08-01

Full Text Available The maintenance of species-specific behaviors for animals in zoological institutions is of top priority, as this can help ensure high levels of animal welfare. Strict feeding schedules within institutions can often impact natural foraging behaviors of animals, as they are no longer required to seek out or manipulate food items. In the wild, western lowland gorillas would spend a majority of their time foraging. The goal of the current study was to examine the impact of different forms of environmental enrichment on activity and foraging levels in gorillas at the Brookfield Zoo. Results suggest that automatic belt feeders that can feed at randomized times, will have the largest impact on behavior of all enrichment tested. However, there were individual differences observed between animals and the level of impact on their behavior. Using enrichment to increase the amount of time that zoo-housed gorillas spend searching for, acquiring, and consuming food can increase their overall activity levels and shift their behavior towards a more naturalistic direction.

Use of biosolids to enhance rangeland forage quality.

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

2010-05-01

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

Moving evidence into practice: cost analysis and assessment of macaques' sustained behavioral engagement with videogames and foraging devices.

Science.gov (United States)

Bennett, Allyson J; Perkins, Chaney M; Tenpas, Parker D; Reinebach, Alma L; Pierre, Peter J

2016-12-01

Environmental enrichment plans for captive nonhuman primates often include provision of foraging devices. The rationale for using foraging devices is to promote species-typical activity patterns that encourage physical engagement and provide multi-sensory stimulation. However, these devices have been shown to be ineffective at sustaining manipulation over long periods of time, and often produce minimal cognitive engagement. Here we use an evidence-based approach to directly compare the amount of object-directed behavior with a foraging device and a computer-based videogame system. We recorded 11 adult male rhesus monkeys' interactions with a foraging device and two tasks within a joystick videogame cognitive test battery. Both techniques successfully produced high levels of engagement during the initial 20 min of observation. After 1 hr the monkeys manipulated the foraging device significantly less than the joystick, F(2,10) = 43.93, P videogame play for the majority of a 5 hr period, provided that they received a 94 mg chow pellet upon successful completion of trials. Using a model approach, we developed previously as a basis for standardized cost:benefit analysis to inform facility decisions, we calculated the comprehensive cost of incorporating a videogame system as an enrichment strategy. The videogame system has a higher initial cost compared to widely-used foraging devices, however, the ongoing labor and supply costs are relatively low. Our findings add to two decades of empirical studies by a number of laboratories that have demonstrated the successful use of videogame-based systems to promote sustained non-social cognitive engagement for macaques. The broader significance of the work lies in the application of a systematic approach to compare and contrast enrichment strategies and encourage evidence-based decision making when choosing an enrichment strategy in a manner that promotes meaningful cognitive enrichment to the animals. © 2016 Wiley

Moving Evidence into Practice: Cost Analysis and Assessment of Macaques’ Sustained Behavioral Engagement with Videogames and Foraging Devices

Science.gov (United States)

Bennett, Allyson J.; Perkins, Chaney M.; Tenpas, Parker D.; Reinebach, Alma L.; Pierre, Peter J.

2017-01-01

Environmental enrichment plans for captive nonhuman primates often include provision of foraging devices. The rationale for using foraging devices is to promote species-typical activity patterns that encourage physical engagement and provide multi-sensory stimulation. However, these devices have been shown to be ineffective at sustaining manipulation over long periods of time, and often produce minimal cognitive engagement. Here we use an evidence-based approach to directly compare the amount of object-directed behavior with a foraging device and a computer-based videogame system. We recorded 11adult male rhesus monkeys’ interactions with a foraging device and two tasks within a joystick videogame cognitive test battery. Both techniques successfully produced high levels of engagement during the initial 20-min of observation. After 1-hr the monkeys manipulated the foraging device significantly less than the joystick, F(2,10)= 43.93, p videogame play for the majority of a 5-hr period, provided that they received a 94mg chow pellet upon successful completion of trials. Using a model approach we developed previously as a basis for standardized cost:benefit analysis to inform facility decisions, we calculated the comprehensive cost of incorporating a videogame system as an enrichment strategy. The videogame system has a higher initial cost compared to widely-used foraging devices however, the ongoing labor and supply costs are relatively low. Our findings add to two decades of empirical studies by a number of laboratories that have demonstrated the successful use of videogame-based systems to promote sustained non-social cognitive engagement for macaques. The broader significance of the work lies in the application of a systematic approach to compare and contrast enrichment strategies and encourage evidence-based decision making when choosing an enrichment strategy in a manner that promotes meaningful cognitive enrichment to the animals. PMID:27404766

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

International Nuclear Information System (INIS)

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

1991-03-01

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

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

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Julieta Grajales-Conesa

2012-03-01

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

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

DEFF Research Database (Denmark)

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

2013-01-01

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

Analysis of Canadian and Irish forage, oats and commercially available equine concentrate feed for pathogenic fungi and mycotoxins

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Buckley Thomas

2007-04-01

Full Text Available Abstract Respiratory infections, recurrent airway obstruction (RAO and exercise induced pulmonary haemorrhage (EIPH are major causes of poor performance in horses. Fungi and mycotoxins are now recognised as a major cause of these conditions. The most notable fungi are Aspergillus and Fusarium. Fungal spores can originate from forage, bedding and feed and, in turn, these fungal spores can produce a series of mycotoxins as secondary metabolites. This study set out to ascertain the degree of fungal and mycotoxin contamination in feed and fodder used in Irish racing yards over a one-year period. Weather conditions in forage producing areas were sampled by Met Eireann and the Canadian Meteorological Service. Fifty per cent of Irish hay, 37% of haylage and 13% of Canadian hay contained pathogenic fungi. Of the mycotoxins, T2 and zearalenone were most prominent. Twenty-one per cent of Irish hay and 16% of pelleted feed contained zearalenone. Forty per cent of oats and 54% of pelleted feed contained T2 toxins.

Analysis of Canadian and Irish forage, oats and commercially available equine concentrate feed for pathogenic fungi and mycotoxins.

Science.gov (United States)

Buckley, Thomas; Creighton, Alan; Fogarty, Ursula

2007-04-01

Respiratory infections, recurrent airway obstruction (RAO) and exercise induced pulmonary haemorrhage (EIPH) are major causes of poor performance in horses. Fungi and mycotoxins are now recognised as a major cause of these conditions. The most notable fungi are Aspergillus and Fusarium. Fungal spores can originate from forage, bedding and feed and, in turn, these fungal spores can produce a series of mycotoxins as secondary metabolites.This study set out to ascertain the degree of fungal and mycotoxin contamination in feed and fodder used in Irish racing yards over a one-year period. Weather conditions in forage producing areas were sampled by Met Eireann and the Canadian Meteorological Service.Fifty per cent of Irish hay, 37% of haylage and 13% of Canadian hay contained pathogenic fungi. Of the mycotoxins, T2 and zearalenone were most prominent. Twenty-one per cent of Irish hay and 16% of pelleted feed contained zearalenone. Forty per cent of oats and 54% of pelleted feed contained T2 toxins.

Patch dynamics of a foraging assemblage of bees.

Science.gov (United States)

Wright, David Hamilton

1985-03-01

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

Contrafreeloading in grizzly bears: implications for captive foraging enrichment.

Science.gov (United States)

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

2010-01-01

Although traditional feeding regimens for captive animals were focused on meeting physiological needs to assure good health, more recently emphasis has also been placed on non-nutritive aspects of feeding. The provision of foraging materials to diversify feeding behavior is a common practice in zoos but selective consumption of foraging enrichment items over more balanced "chow" diets could lead to nutrient imbalance. One alternative is to provide balanced diets in a contrafreeloading paradigm. Contrafreeloading occurs when animals choose resources that require effort to exploit when identical resources are freely available. To investigate contrafreeloading and its potential as a theoretical foundation for foraging enrichment, we conducted two experiments with captive grizzly bears (Ursus arctos horribilis). In Experiment 1, bears were presented with five foraging choices simultaneously: apples, apples in ice, salmon, salmon in ice, and plain ice under two levels of food restriction. Two measures of contrafreeloading were considered: weight of earned food consumed and time spent working for earned food. More free than earned food was eaten, with only two bears consuming food extracted from ice, but all bears spent more time manipulating ice containing salmon or apples than plain ice regardless of level of food restriction. In Experiment 2, food-restricted bears were presented with three foraging choices simultaneously: apples, apples inside a box, and an empty box. Although they ate more free than earned food, five bears consumed food from boxes and all spent more time manipulating boxes containing apples than empty boxes. Our findings support the provision of contrafreeloading opportunities as a foraging enrichment strategy for captive wildlife. (c) 2009 Wiley-Liss, Inc.

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 2. Meat quality, fatty acid composition, and overall palatability.

Science.gov (United States)

Faucitano, L; Chouinard, P Y; Fortin, J; Mandell, I B; Lafrenière, C; Girard, C L; Berthiaume, R

2008-07-01

Five beef cattle management regimens were evaluated for their effect on meat quality, fatty acid composition, and overall palatability of the longis-simus dorsi (LD) muscle in Angus cross steers. A 98-d growing phase was conducted using grass silage with or without supplementation of growth promotants (Revalor G and Rumensin) or soybean meal. Dietary treatments in the finishing phase were developed with or without supplementation of growth promotants based on exclusive feeding of forages with no grain supplementation, or the feeding of grain:forage (70:30) diets. Growth promotants increased (P forages increased the proportion of cis-9, cis-12, cis-15 C18:3 as well as several other isomers of the n-3 family and decreased in the ratio of n-6 to n-3 fatty acids in the LD muscle as compared with supplementing grain (P forage-based diet increased (P Forage feeding also increased the proportion of cis-9, trans-11 C18:2 (P forage-finishing and growth promotants-free beef production system.

Sediment-induced turbidity impairs foraging performance and prey choice of planktivorous coral reef fishes.

Science.gov (United States)

Johansen, J L; Jones, G P

2013-09-01

Sedimentation is a substantial threat to aquatic ecosystems and a primary cause of habitat degradation on near-shore coral reefs. Although numerous studies have demonstrated major impacts of sedimentation and turbidity on corals, virtually nothing is known of the sensitivity of reef fishes. Planktivorous fishes are an important trophic group that funnels pelagic energy sources into reef ecosystems. These fishes are visual predators whose foraging is likely to be impaired by turbidity, but the threshold for such effects and their magnitude are unknown. This study examined the effect of sediment-induced turbidity on foraging in four species of planktivorous damselfishes (Pomacentridae) of the Great Barrier Reef, including inshore and offshore species that potentially differ in tolerance for turbidity. An experimental flow tunnel was used to quantify their ability to catch mobile and immobile planktonic prey under different levels of turbidity and velocity in the range encountered on natural and disturbed reefs. Turbidity of just 4 NTU (nephelometric turbidity units) reduced average attack success by up to 56%, with higher effect sizes for species with offshore distributions. Only the inshore species (Neopomacentrus bankieri), which frequently encounters this turbidity on coastal reefs, could maintain high prey capture success. At elevated turbidity similar to that found on disturbed reefs (8 NTU), attack success was reduced in all species examined by up to 69%. These reductions in attack success led to a 21-24% decrease in foraging rates for all mid to outer-shelf species, in spite of increasing attack rates at high turbidity. Although effects of turbidity varied among species, it always depended heavily on prey mobility and ambient velocity. Attack success was up to 14 times lower on mobile prey, leaving species relatively incapable of foraging on anything but immobile prey at high turbidity. Effects of turbidity were particularly prominent at higher velocities, as

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

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Ralph J Stelzer

2010-03-01

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

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

Science.gov (United States)

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

2010-03-05

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

Amygdala Signaling during Foraging in a Hazardous Environment.

Science.gov (United States)

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

2015-09-23

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

Wolf, Canis lupus, visits to white-tailed deer, Odocoileus virginianus, summer ranges: Optimal foraging?

Science.gov (United States)

Demma, D.J.; Mech, L.D.

2009-01-01

We tested whether Wolf (Canis lupus) visits to individual female White-tailed Deer (Odocoileus virginianus) summer ranges during 2003 and 2004 in northeastern Minnesota were in accord with optimal-foraging theory. Using GPS collars with 10- to 30-minute location attempts on four Wolves and five female deer, plus eleven VHF-collared female deer in the Wolves' territory, provided new insights into the frequency of Wolf visits to summer ranges of female deer. Wolves made a mean 0.055 visits/day to summer ranges of deer three years and older, significantly more than their 0.032 mean visits/day to ranges of two-year-old deer, which generally produce fewer fawns, and most Wolf visits to ranges of older deer were much longer than those to ranges of younger deer. Because fawns comprise the major part of the Wolf's summer diet, this Wolf behavior accords with optimal-foraging theory.

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

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Novia Qomariyah

2014-01-01

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

More milk from forage: Milk production, blood metabolites, and forage intake of dairy cows grazing pasture mixtures and spatially adjacent monocultures.

Science.gov (United States)

Pembleton, Keith G; Hills, James L; Freeman, Mark J; McLaren, David K; French, Marion; Rawnsley, Richard P

2016-05-01

There is interest in the reincorporation of legumes and forbs into pasture-based dairy production systems as a means of increasing milk production through addressing the nutritive value limitations of grass pastures. The experiments reported in this paper were undertaken to evaluate milk production, blood metabolite concentrations, and forage intake levels of cows grazing either pasture mixtures or spatially adjacent monocultures containing perennial ryegrass (Lolium perenne), white clover (Trifolium repens), and plantain (Plantago lanceolata) compared with cows grazing monocultures of perennial ryegrass. Four replicate herds, each containing 4 spring-calving, cross-bred dairy cows, grazed 4 different forage treatments over the periods of early, mid, and late lactation. Forage treatments were perennial ryegrass monoculture (PRG), a mixture of white clover and plantain (CPM), a mixture of perennial ryegrass, white clover, and plantain (RCPM), and spatially adjacent monocultures (SAM) of perennial ryegrass, white clover, and plantain. Milk volume, milk composition, blood fatty acids, blood β-hydroxybutyrate, blood urea N concentrations, live weight change, and estimated forage intake were monitored over a 5-d response period occurring after acclimation to each of the forage treatments. The acclimation period for the early, mid, and late lactation experiments were 13, 13, and 10 d, respectively. Milk yield (volume and milk protein) increased for cows grazing the RCPM and SAM in the early lactation experiment compared with cows grazing the PRG, whereas in the mid lactation experiment, milk fat increased for the cows grazing the RCPM and SAM when compared with the PRG treatments. Improvements in milk production from grazing the RCPM and SAM treatments are attributed to improved nutritive value (particularly lower neutral detergent fiber concentrations) and a potential increase in forage intake. Pasture mixtures or SAM containing plantain and white clover could be a

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.

RNAi-mediated silencing of vitellogenin gene function turns honeybee ( Apis mellifera) workers into extremely precocious foragers

Science.gov (United States)

Marco Antonio, David Santos; Guidugli-Lazzarini, Karina Rosa; Do Nascimento, Adriana Mendes; Simões, Zilá Luz Paulino; Hartfelder, Klaus

2008-10-01

The switch from within-hive activities to foraging behavior is a major transition in the life cycle of a honeybee ( Apis mellifera) worker. A prominent regulatory role in this switch has long been attributed to juvenile hormone (JH), but recent evidence also points to the yolk precursor protein vitellogenin as a major player in behavioral development. In the present study, we injected vitellogenin double-stranded RNA (dsVg) into newly emerged worker bees of Africanized genetic origin and introduced them together with controls into observation hives to record flight behavior. RNA interference-mediated silencing of vitellogenin gene function shifted the onset of long-duration flights (>10 min) to earlier in life (by 3 4 days) when compared with sham and untreated control bees. In fact, dsVg bees were observed conducting such flights extremely precociously, when only 3 days old. Short-duration flights (<10 min), which bees usually perform for orientation and cleaning, were not affected. Additionally, we found that the JH titer in dsVg bees collected after 7 days was not significantly different from the controls. The finding that depletion of the vitellogenin titer can drive young bees to become extremely precocious foragers could imply that vitellogenin is the primary switch signal. At this young age, downregulation of vitellogenin gene activity apparently had little effect on the JH titer. As this unexpected finding stands in contrast with previous results on the vitellogenin/JH interaction at a later age, when bees normally become foragers, we propose a three-step sequence in the constellation of physiological parameters underlying behavioral development.

Foraging behaviour of pink-footed geese (Anser brachyrhynchus) during spring migration

DEFF Research Database (Denmark)

Chudzińska, Magda Ewa

and their energetic consequences are therefore of great importance to these birds. In this thesis, I have aimed to address some aspects of the foraging decisions and behaviour of pink-footed geese during their spring migration to the Arctic breeding area. I combined field techniques with telemetry technology as well...... as modelling tools to address questions about how geese forage and fuel during their spring migration. The first three presented manuscripts focus on changes in goose foraging behaviour and energetics over the course of the day, a stopover season and the entire migration. They also focus on variety of factors...... the question: which foraging decision do geese make at the Mid-Norway stopover site....

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

DEFF Research Database (Denmark)

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

2014-01-01

exist, as in the North Sea. Sandeel appears to be the most important prey forage fish. Seabirds are most dependent on forage fish, due to specialized diet and distributional constraints (breeding colonies). Other than fisheries, key predators of forage fish are a few piscivorous fish species including...... saithe, whiting, mackerel, and horse-mackerel, exploited in turn by fisheries; seabirds and seals have a more modest impact. Size-based foodwebmodelling suggests that reducing fishing mortality may not necessarily lead to larger stocks of piscivorous fish, especially if their early life stages compete...

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.

The amino acid composition of rumen-undegradable protein: a comparison between forages.

Science.gov (United States)

Edmunds, B; Südekum, K-H; Bennett, R; Schröder, A; Spiekers, H; Schwarz, F J

2013-07-01

The objective of this study was to improve knowledge regarding the amino acid profile of the insoluble portion of ingested forage escaping rumen degradation. Six forage categories were analyzed. Categories varied in botanical composition and each contained 2 samples. Samples within categories were derived from the same parent material but differed in harvest, maturity, or conservation type. The rumen-undegradable protein of all forages was measured by incubation for 16h in the rumen of 3 nonlactating cows. All residues were corrected for microbial colonization. The AA profile of the residue was different to the original profile. Degradation trends of individual AA, in terms of increase or decrease relative to the original concentration, were similar between all forages. The AA profiles of forage residues, both within and between categories, were more similar to each other than to their respective original profile. This information may aid in improving the accuracy of estimating postruminal AA supply from forages while decreasing the number of samples required to be analyzed. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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

Science.gov (United States)

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

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,...

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,...

Social foraging by waterbirds in shallow coastal lagoons in Ghana

NARCIS (Netherlands)

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

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

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.

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

African Journals Online (AJOL)

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

Cost of living dictates what whales, dolphins and porpoises eat: the importance of prey quality on predator foraging strategies.

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Jérôme Spitz

Full Text Available Understanding the mechanisms that drive prey selection is a major challenge in foraging ecology. Most studies of foraging strategies have focused on behavioural costs, and have generally failed to recognize that differences in the quality of prey may be as important to predators as the costs of acquisition. Here, we tested whether there is a relationship between the quality of diets (kJ · g(-1 consumed by cetaceans in the North Atlantic and their metabolic costs of living as estimated by indicators of muscle performance (mitochondrial density, n = 60, and lipid content, n = 37. We found that the cost of living of 11 cetacean species is tightly coupled with the quality of prey they consume. This relationship between diet quality and cost of living appears to be independent of phylogeny and body size, and runs counter to predictions that stem from the well-known scaling relationships between mass and metabolic rates. Our finding suggests that the quality of prey rather than the sheer quantity of food is a major determinant of foraging strategies employed by predators to meet their specific energy requirements. This predator-specific dependence on food quality appears to reflect the evolution of ecological strategies at a species level, and has implications for risk assessment associated with the consequences of changing the quality and quantities of prey available to top predators in marine ecosystems.

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

Science.gov (United States)

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

2015-01-01

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

Foraging behavior of pileated woodpeckers in partial cut and uncut bottomland hardwood forest

Science.gov (United States)

Newell, P.; King, Sammy L.; Kaller, Michael D.

2009-01-01

In bottomland hardwood forests, partial cutting techniques are increasingly advocated and used to create habitat for priority wildlife like Louisiana black bear (Ursus americanus luteolus), white-tailed deer (Odocoileus virginianus), and Neotropical migrants. Although partial cutting may be beneficial to some species, those that use dead wood may be negatively affected since large diameter and poor quality trees (deformed, moribund, or dead) are rare, but normally targeted for removal. On the other hand, partial cutting can create dead wood if logging slash is left on-site. We studied foraging behavior of pileated woodpeckers (Dryocopus pileatus) in one- and two-year-old partial cuts designed to benefit priority species and in uncut forest during winter, spring, and summer of 2006 and 2007 in Louisiana. Males and females did not differ in their use of tree species, dbh class, decay class, foraging height, use of foraging tactics or substrate types; however, males foraged on larger substrates than females. In both partial cut and uncut forest, standing live trees were most frequently used (83% compared to 14% for standing dead trees and 3% for coarse woody debris); however, dead trees were selected (i.e. used out of proportion to availability). Overcup oak (Quercus lyrata) and bitter pecan (Carya aquatica) were also selected and sugarberry (Celtis laevigata) avoided. Pileated woodpeckers selected trees >= 50 cm dbh and avoided trees in smaller dbh classes (10-20 cm). Density of selected foraging substrates was the same in partial cut and uncut forest. Of the foraging substrates, woodpeckers spent 54% of foraging time on live branches and boles, 37% on dead branches and boles, and 9% on vines. Of the foraging tactics, the highest proportion of foraging time was spent excavating (58%), followed by pecking (14%), gleaning (14%), scaling (7%), berry-eating (4%), and probing (3%). Woodpecker use of foraging tactics and substrates, and foraging height and substrate

Considerations for Managing Agricultural Co-Existence between Transgenic and Non-Transgenic Cultivars of Outcrossing Perennial Forage Plants in Dairy Pastures

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Kevin F. Smith

2016-11-01

Full Text Available Many of the major forage species used in agriculture are outcrossing and rely on the exchange of pollen between individuals for reproduction; this includes the major species used for dairy production in grazing systems: perennial ryegrass (Lolium perenne L. and white clover (Trifolium repens L.. Cultivars of these species have been co-existing since contrasting cultivars were developed using plant breeding, but the consequences and need for strategies to manage co-existence have been made more prominent with the advent of genetic modification. Recent technological developments have seen the experimental evaluation of genetically modified (GM white clover and perennial ryegrass, although there is no current commercial growing of GM cultivars of these species. Co-existence frameworks already exist for two major cross-pollinated grain crops (canola and maize in Europe, and for alfalfa (Medicago sativa L. in the US, so many of the principles that the industry has developed for co-existence in these crops such as detection techniques, segregation, and agronomic management provide lessons and guidelines for outcrossing forage species, that are discussed in this paper.

The Müller-Lyer illusion in ant foraging.

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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.

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

Science.gov (United States)

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

2017-01-01

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

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

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

African Journals Online (AJOL)

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

A Novel Plant Root Foraging Algorithm for Image Segmentation Problems

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Lianbo Ma

2014-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1996-04-01

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

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

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Lisa J Evans

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

Seed storage effects on germination for two forage kochia cultivars

Science.gov (United States)

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

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

African Journals Online (AJOL)

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

Mercury in San Francisco Bay forage fish

Energy Technology Data Exchange (ETDEWEB)

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

2010-08-15

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

Mercury in San Francisco Bay forage fish

International Nuclear Information System (INIS)

Greenfield, Ben K.; Jahn, Andrew

2010-01-01

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

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

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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

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

Science.gov (United States)

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

2018-01-01

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

Loggerhead turtles (Caretta caretta use vision to forage on gelatinous prey in mid-water.

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Tomoko Narazaki

Full Text Available Identifying characteristics of foraging activity is fundamental to understanding an animals' lifestyle and foraging ecology. Despite its importance, monitoring the foraging activities of marine animals is difficult because direct observation is rarely possible. In this study, we use an animal-borne imaging system and three-dimensional data logger simultaneously to observe the foraging behaviour of large juvenile and adult sized loggerhead turtles (Caretta caretta in their natural environment. Video recordings showed that the turtles foraged on gelatinous prey while swimming in mid-water (i.e., defined as epipelagic water column deeper than 1 m in this study. By linking video and 3D data, we found that mid-water foraging events share the common feature of a marked deceleration phase associated with the capture and handling of the sluggish prey. Analysis of high-resolution 3D movements during mid-water foraging events, including presumptive events extracted from 3D data using deceleration in swim speed as a proxy for foraging (detection rate = 0.67, showed that turtles swam straight toward prey in 171 events (i.e., turning point absent but made a single turn toward the prey an average of 5.7±6.0 m before reaching the prey in 229 events (i.e., turning point present. Foraging events with a turning point tended to occur during the daytime, suggesting that turtles primarily used visual cues to locate prey. In addition, an incident of a turtle encountering a plastic bag while swimming in mid-water was recorded. The fact that the turtle's movements while approaching the plastic bag were analogous to those of a true foraging event, having a turning point and deceleration phase, also support the use of vision in mid-water foraging. Our study shows that integrated video and high-resolution 3D data analysis provides unique opportunities to understand foraging behaviours in the context of the sensory ecology involved in prey location.

Field margins, foraging distances and their impacts on nesting pollinator success.

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Sean A Rands

Full Text Available The areas of wild land around the edges of agricultural fields are a vital resource for many species. These include insect pollinators, to whom field margins provide both nest sites and important resources (especially when adjacent crops are not in flower. Nesting pollinators travel relatively short distances from the nest to forage: most species of bee are known to travel less than two kilometres away. In order to ensure that these pollinators have sufficient areas of wild land within reach of their nests, agricultural landscapes need to be designed to accommodate the limited travelling distances of nesting pollinators. We used a spatially-explicit modelling approach to consider whether increasing the width of wild strips of land within the agricultural landscape will enhance the amount of wild resources available to a nesting pollinator, and if it would impact differently on pollinators with differing foraging strategies. This was done both by creating field structures with a randomised geography, and by using landscape data based upon the British agricultural landscape. These models demonstrate that enhancing field margins should lead to an increase in the availability of forage to pollinators that nest within the landscape. With the exception of species that only forage within a very short range of their nest (less than 125 m, a given amount of field margin manipulation should enhance the proportion of land available to a pollinator for foraging regardless of the distance over which it normally travels to find food. A fixed amount of field edge manipulation should therefore be equally beneficial for both longer-distance nesting foragers such as honeybees, and short-distance foragers such as solitary bees.

Levy Foraging in a Dynamic Environment – Extending the Levy Search

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Vincenzo Fioriti

2015-07-01

Full Text Available A common task for robots is the patrolling of an unknown area with inadequate information about target locations. Under these circumstances it has been suggested that animal foraging could provide an optimal or at least sub-optimal search methodology, namely the Levy flight search. Although still in debate, it seems that predators somehow follow this search pattern when foraging, because it avoids being trapped in a local search if the food is beyond the sensory range. A Levy flight is a particular case of the random walk. Its displacements on a 2-D surface are drawn from the Pareto-Levy probability distribution, characterized by power law tails. The Levy flight search has many applications in optical material, ladars, optics, large database search, earthquake data analysis, location of DNA sites, human mobility, stock return analysis, online auctions, astronomy, ecology and biology. Almost all studies and simulations concerning the Levy flight foraging examine static or slowly moving (with respect to the forager uniformly distributed resources. Moreover, in recent works a small swarm of underwater autonomous vehicles has been used to test the standard Levy search in the underwater environment, with good results. In this paper we extend the classical Levy foraging framework taking into consideration a moving target allocated on a 2-D surface according to a radial probability distribution and comparing its performance with the random walk search. The metric used in the numerical simulations is the detection rate. Simulations include the sensor resolution, intended as the maximum detection distance of the forager from the target. Furthermore, contrarily to the usual Levy foraging framework, we use only one target. Results show that Levy flight outperforms the random walk if the sensor detection radius is not too small or too large. We also find the Levy flight in the velocity of the center of mass model of a fish school according the Kuramoto

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

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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.

Local Orientation and the Evolution of Foraging: Changes in Decision Making Can Eliminate Evolutionary Trade-offs

Science.gov (United States)

van der Post, Daniel J.; Semmann, Dirk

2011-01-01

Information processing is a major aspect of the evolution of animal behavior. In foraging, responsiveness to local feeding opportunities can generate patterns of behavior which reflect or “recognize patterns” in the environment beyond the perception of individuals. Theory on the evolution of behavior generally neglects such opportunity-based adaptation. Using a spatial individual-based model we study the role of opportunity-based adaptation in the evolution of foraging, and how it depends on local decision making. We compare two model variants which differ in the individual decision making that can evolve (restricted and extended model), and study the evolution of simple foraging behavior in environments where food is distributed either uniformly or in patches. We find that opportunity-based adaptation and the pattern recognition it generates, plays an important role in foraging success, particularly in patchy environments where one of the main challenges is “staying in patches”. In the restricted model this is achieved by genetic adaptation of move and search behavior, in light of a trade-off on within- and between-patch behavior. In the extended model this trade-off does not arise because decision making capabilities allow for differentiated behavioral patterns. As a consequence, it becomes possible for properties of movement to be specialized for detection of patches with more food, a larger scale information processing not present in the restricted model. Our results show that changes in decision making abilities can alter what kinds of pattern recognition are possible, eliminate an evolutionary trade-off and change the adaptive landscape. PMID:21998571

Foraging strategy of little auks during chick rearing in northwest Greenland

DEFF Research Database (Denmark)

Mosbech, Anders; Møller, Eva Friis; Johansen, Kasper Lambert

of the ongoing warming of the Arctic. Here we present the first results from GPS tracking of breeding little auks in northwest Greenland, involving data from four different breeding colonies. We examine time budgets, foraging trip patterns and habitat preferences at foraging areas, including comparison......Foraging strategy of little auks during chick rearing in northwest Greenland Anders Mosbech, Kasper Johansen, Eva Friis Møller & Peter Lyngs Department of Biology and Arctic Center, Aarhus University, Denmark An estimated 80 % of the global little auk population breeds in the coastal landscape...... bordering the north water polynya in high Arctic northwest Greenland, and from this main breeding area very little is known on foraging behavior. Little auks are feeding on lipid-rich copepods associated with cold artic waters, and are potentially important for monitoring and assessing the impact...

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

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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.

Habitat and forage associations of a naturally colonising insect pollinator, the Tree Bumblebee Bombus hypnorum

OpenAIRE

Crowther, Liam P.; Hein, Pierre-Louis; Bourke, Andrew F. G.

2014-01-01

Bumblebees (Bombus species) are major pollinators of commercial crops and wildflowers but factors affecting their abundance, including causes of recent population declines, remain unclear. Investigating the ecology of species with expanding ranges provides a potentially powerful means of elucidating these factors. Such species may also bring novel pollination services to their new ranges. We therefore investigated landscape-scale habitat use and foraging preferences of the Tree Bumblebee, B. ...

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…

Boldness affects foraging decisions in barnacle geese: an experimental approach

NARCIS (Netherlands)

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

2012-01-01

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

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

Science.gov (United States)

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

2017-02-01

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

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

DEFF Research Database (Denmark)

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

2007-01-01

in the leaf-litter and some as conspicuous swarm raiders on the forest floor and in the lower vegetation (the infamous driver ants). Here we use a combination of nuclear and mitochondrial DNA sequences to reconstruct the phylogeny of the Dorylus s.l. army ants and to infer the evolutionary transitions...... in foraging niche and associated morphological adaptations. RESULTS: Underground foraging is basal and gave rise to leaf-litter foraging. Leaf-litter foraging in turn gave rise to two derived conditions: true surface foraging (the driver ants) and a reversal to subterranean foraging (a clade with most......BACKGROUND: Army ants are the prime arthropod predators in tropical forests, with huge colonies and an evolutionary derived nomadic life style. Five of the six recognized subgenera of Old World Dorylus army ants forage in the soil, whereas some species of the sixth subgenus (Anomma) forage...

Food availability and foraging near human developments by black bears

Science.gov (United States)

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

2013-01-01

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

Information Foraging in E-Voting

DEFF Research Database (Denmark)

Vatrapu, Ravi; Robertson, Scott

2009-01-01

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

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

Science.gov (United States)

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

2016-10-01

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

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

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Charlie M. Shackleton

2017-10-01

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

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

Science.gov (United States)

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

2018-06-13

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

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

International Nuclear Information System (INIS)

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

1982-01-01

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

Ruminal fermentation of Anti-methanogenic Nitrate- and Nitro-Containing Forages In Vitro

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Robin C. Anderson

2016-08-01

Full Text Available Nitrate, 3-nitro-1-propionic acid (NPA and 3-nitro-1-propanol (NPOH can accumulate in forages and be poisonous to animals if consumed in high enough amounts. These chemicals are also recognized as potent anti-methanogenic compounds, but plants naturally containing these chemicals have been studied little in this regard. Presently, we found that nitrate-, NPA- or NPOH-containing forages effectively decreased methane production, by 35 to 87%, during in vitro fermentation by mixed cultures of ruminal microbes compared to fermentation by cultures incubated similarly with alfalfa. Methane production was further decreased during incubation of mixed cultures also inoculated with Denitrobacterium detoxificans, a ruminal bacterium known to metabolize nitrate, NPA and NPOH. Inhibition of methanogens within the mixed cultures was greatest with the NPA- and NPOH-containing forages. Hydrogen accumulated in all the mixed cultures incubated with forages containing nitrate, NPA or NPOH but was dramatically higher, exceeding 40 µmol hydrogen/mL, in mixed cultures incubated with NPA-containing forage but not inoculated with D. detoxificans. This possibly reflects the inhibition of hydrogenase-catalyzed uptake of hydrogen produced via conversion of 50 µmol added formate per mL to hydrogen. Accumulations of volatile fatty acids revealed compensatory changes in fermentation in mixed cultures incubated with the nitrate-, NPA- and NPOH-containing forages as evidenced by lower accumulations of acetate, and in some cases higher accumulations of butyrate and lower accumulations of ammonia, iso-buytrate and iso-valerate compared to cultures incubated with alfalfa. Results reveal that nitrate, NPA and NPOH that accumulate naturally in forages can be made available within ruminal incubations to inhibit methanogenesis. Further research is warranted to determine if diets can be formulated with nitrate-, NPA- and NPOH-containing forages to achieve efficacious mitigation in

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

DEFF Research Database (Denmark)

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

2012-01-01

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

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

Science.gov (United States)

2010-11-05

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

Seasonal Variation in Parental Care Drives Sex-Specific Foraging by a Monomorphic Seabird.

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Burke, Chantelle M; Montevecchi, William A; Regular, Paul M

2015-01-01

Evidence of sex-specific foraging in monomorphic seabirds is increasing though the underlying mechanisms remain poorly understood. We investigate differential parental care as a mechanism for sex-specific foraging in monomorphic Common Murres (Uria aalge), where the male parent alone provisions the chick after colony departure. Using a combination of geolocation-immersion loggers and stable isotopes, we assess two hypotheses: the reproductive role specialization hypothesis and the energetic constraint hypothesis. We compare the foraging behavior of females (n = 15) and males (n = 9) during bi-parental at the colony, post-fledging male-only parental care and winter when parental care is absent. As predicted by the reproductive role specialization hypothesis, we found evidence of sex-specific foraging during post-fledging only, the stage with the greatest divergence in parental care roles. Single-parenting males spent almost twice as much time diving per day and foraged at lower quality prey patches relative to independent females. This implies a potential energetic constraint for males during the estimated 62.8 ± 8.9 days of offspring dependence at sea. Contrary to the predictions of the energetic constraint hypothesis, we found no evidence of sex-specific foraging during biparental care, suggesting that male parents did not forage for their own benefit before colony departure in anticipation of post-fledging energy constraints. We hypothesize that unpredictable prey conditions at Newfoundland colonies in recent years may limit male parental ability to allocate additional time and energy to self-feeding during biparental care, without compromising chick survival. Our findings support differential parental care as a mechanism for sex-specific foraging in monomorphic murres, and highlight the need to consider ecological context in the interpretation of sex-specific foraging behavior.

Seasonal Variation in Parental Care Drives Sex-Specific Foraging by a Monomorphic Seabird.

Directory of Open Access Journals (Sweden)

Chantelle M Burke

Full Text Available Evidence of sex-specific foraging in monomorphic seabirds is increasing though the underlying mechanisms remain poorly understood. We investigate differential parental care as a mechanism for sex-specific foraging in monomorphic Common Murres (Uria aalge, where the male parent alone provisions the chick after colony departure. Using a combination of geolocation-immersion loggers and stable isotopes, we assess two hypotheses: the reproductive role specialization hypothesis and the energetic constraint hypothesis. We compare the foraging behavior of females (n = 15 and males (n = 9 during bi-parental at the colony, post-fledging male-only parental care and winter when parental care is absent. As predicted by the reproductive role specialization hypothesis, we found evidence of sex-specific foraging during post-fledging only, the stage with the greatest divergence in parental care roles. Single-parenting males spent almost twice as much time diving per day and foraged at lower quality prey patches relative to independent females. This implies a potential energetic constraint for males during the estimated 62.8 ± 8.9 days of offspring dependence at sea. Contrary to the predictions of the energetic constraint hypothesis, we found no evidence of sex-specific foraging during biparental care, suggesting that male parents did not forage for their own benefit before colony departure in anticipation of post-fledging energy constraints. We hypothesize that unpredictable prey conditions at Newfoundland colonies in recent years may limit male parental ability to allocate additional time and energy to self-feeding during biparental care, without compromising chick survival. Our findings support differential parental care as a mechanism for sex-specific foraging in monomorphic murres, and highlight the need to consider ecological context in the interpretation of sex-specific foraging behavior.

Foraging strategy switch of a top marine predator according to seasonal resource differences

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Malcolm Daniel O'Toole

2015-04-01

Full Text Available The spatio-temporal variability in marine resources influences the foraging behaviour and success of top marine predators. However, little is known about the links between these animals and ocean productivity, specifically, how plankton density influences their foraging behaviour. Southern elephant seals (Mirounga leonina have two annual at-sea foraging trips: a two month post-breeding foraging trip (Nov – Jan that coincides with elevated summer productivity; and an eight month post-moulting foraging trip (Feb – Oct over winter, when productivity is low. Physical parameters are often used to describe seal habitat, whereas information about important biological parameters is lacking. We used electronic tags deployed on elephant seals during both trips to determine their movement and foraging behaviour. The tags also recorded light, which measured the bio-optical properties of the water column, the bulk of which is presumably influenced by phytoplankton. We investigated the relationship between plankton density and seal foraging behaviour; comparing trends between summer and winter trips. We found a positive relationship between plankton density and foraging behaviour, which did not vary seasonally. We propose that profitable concentrations of seal prey are more likely to coincide with planktonic aggregations, but we also acknowledge that trophic dynamics may shift in response to seasonal trends in productivity. Seal prey (mid-trophic level and plankton (lower-trophic level are expected to overlap in space and time during summer trips when peak phytoplankton blooms occur. In contrast, aggregated patches of lower trophic levels are likely to be more dispersed during winter trips when plankton density is considerably lower and heterogeneous. These results show that southern elephant seals are able to exploit prey resources in different ways throughout the year as demonstrated by the variation observed between seal foraging behaviour and trophic

Improved forage digestibility of tall fescue (Festuca arundinacea) by transgenic down-regulation of cinnamyl alcohol dehydrogenase.

Science.gov (United States)

Chen, Lei; Auh, Chung-Kyoon; Dowling, Paul; Bell, Jeremey; Chen, Fang; Hopkins, Andrew; Dixon, Richard A; Wang, Zeng-Yu

2003-11-01

Lignification of cell walls during plant development has been identified as the major factor limiting forage digestibility and concomitantly animal productivity. cDNA sequences encoding a key lignin biosynthetic enzyme, cinnamyl alcohol dehydrogenase (CAD), were cloned from the widely grown monocotyledonous forage species tall fescue (Festuca arundinacea Schreb.). Recombinant tall fescue CAD expressed in E. coli exhibited the highest V(max)/K(m) values when coniferaldehyde and sinapaldehyde were used as substrates. Transgenic tall fescue plants carrying either sense or antisense CAD gene constructs were obtained by microprojectile bombardment of single genotype-derived embryogenic suspension cells. Severely reduced levels of mRNA transcripts and significantly reduced CAD enzymatic activities were found in two transgenic plants carrying sense and antisense CAD transgenes, respectively. These CAD down-regulated transgenic lines had significantly decreased lignin content and altered ratios of syringyl (S) to guaiacyl (G), G to p-hydroxyphenyl (H) and S to H units. No significant changes in cellulose, hemicellulose, neutral sugar composition, p-coumaric acid and ferulic acid levels were observed in the transgenic plants. Increases of in vitro dry matter digestibility of 7.2-9.5% were achieved in the CAD down-regulated lines, thus providing a novel germplasm to be used for the development of grass cultivars with improved forage quality.

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

International Nuclear Information System (INIS)

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

1976-01-01

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

Corticosterone predicts foraging behavior and parental care in macaroni penguins.

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

2012-07-01

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

Evaluation some Forage Legumes in Limited Irrigation Condition

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Hassan Moniri Far

2015-11-01

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

SOCIAL COMPLEXITY AND LEARNING FORAGING TASKS IN BEES

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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

Honeybees learn floral odors while receiving nectar from foragers within the hive

Science.gov (United States)

Farina, Walter M.; Grüter, Christoph; Acosta, Luis; Mc Cabe, Sofía

2007-01-01

Recent studies showed that nectar odors brought back by honeybee foragers can be learned associatively inside the hive. In the present study, we focused on the learning abilities of bees, which directly interact via trophallaxis with the incoming nectar foragers: the workers that perform nectar-receiving tasks inside the hive. Workers that have received food directly from foragers coming back from a feeder offering either unscented or scented sugar solution [phenylacetaldehyde (PHE) or nonanal diluted] were captured from two observational hives, and their olfactory memories were tested using the proboscis extension response paradigm. Bees that have received scented solution from incoming foragers showed significantly increased response frequencies for the corresponding solution odor in comparison with those that have received unscented solution. No differences in the response frequencies were found between food odors and colonies. The results indicate that first-order receivers learn via trophallaxis the association between the scent and the sugar solution transferred by incoming foragers. The implications of these results should be considered at three levels: the operational cohesion of bees involved in foraging-related tasks, the information propagation inside the hive related to the floral type exploited, and the putative effect of these memories on future preferences for resources.

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...

Triticale for dairy forage systems

Science.gov (United States)

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

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. ...

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

Science.gov (United States)

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

2010-09-01

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

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

Directory of Open Access Journals (Sweden)

Zhaoqin Li

2010-09-01

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

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

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

Science.gov (United States)

Berlincourt, Maud; Arnould, John P Y

2015-01-01

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

Protein Binding Capacity of Different Forages Tannin

Science.gov (United States)

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

2018-02-01

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

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...

Monitoring Forage Production of California Rangeland Using Remote Sensing Observations

Science.gov (United States)

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

2016-12-01

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

Physiological effects of increased foraging effort in a small passerine.

Science.gov (United States)

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

2017-11-15

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

Testing Optimal Foraging Theory Using Bird Predation on Goldenrod Galls

Science.gov (United States)

Yahnke, Christopher J.

2006-01-01

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

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

African Journals Online (AJOL)

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

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

African Journals Online (AJOL)

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

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

Science.gov (United States)

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

2015-08-01

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

Food limitation of sea lion pups and the decline of forage off central and southern California

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McClatchie, Sam; Field, John; Thompson, Andrew R.; Gerrodette, Tim; Lowry, Mark; Fiedler, Paul C.; Watson, William; Nieto, Karen M.; Vetter, Russell D.

2016-01-01

California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5–38° N) for a decade, suggesting that trends in forage are environmentally driven. PMID:27069651

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...

Adélie penguin foraging location predicted by tidal regime switching.

Science.gov (United States)

Oliver, Matthew J; Irwin, Andrew; Moline, Mark A; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh

2013-01-01

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.

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

OpenAIRE

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

2010-01-01

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

Dynamics of sward condition and botanical composition in mixed pastures of marandugrass, forage peanut and tropical kudzu

Directory of Open Access Journals (Sweden)

Carlos Mauricio Soares de Andrade

2012-03-01

Full Text Available This study was carried out to evaluate the dynamics of sward condition and botanical composition of a mixed pasture of marandugrass (Brachiaria brizantha cv. Marandu, forage peanut (Arachis pintoi cv. Mandobi and tropical kudzu (Pueraria phaseoloides, rotationally stocked at four daily forage allowance levels (6.6, 10.3, 14.3 and 17.9% of live weight. Sward condition was characterized in each stocking cycle by measuring pre- and post-grazing sward height, forage mass and percentage of bare ground. Botanical composition (grass, forage peanut, tropical kudzu and weeds was evaluated before each stocking period. Swards under smaller forage allowances presented lower height, forage mass and ground cover. This condition favored the growth of forage peanut, which constituted 21.1, 15.2, 8.4 and 3.8% of forage mass in the last quarter of the experimental period, from the lowest to the highest forage allowance, respectively. Tropical kudzu was sensitive to all forage allowance levels and its percentage in the botanical composition was strongly reduced along the experimental period, especially during the dry season (July to September. Forage peanut cv. Mandobi and marandugrass form a more balanced mixture when pre-grazing sward height is maintained shorter than 45 cm. Tropical kudzu is intolerant to intensive grazing management systems when associated to marandugrass.

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

Science.gov (United States)

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

2012-01-01

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

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

Directory of Open Access Journals (Sweden)

Caragh G Threlfall

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

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

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Nuru Adgaba

2017-07-01

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

Diet variability of forage fishes in the Northern California Current System

Science.gov (United States)

Hill, Andrew D.; Daly, Elizabeth A.; Brodeur, Richard D.

2015-06-01

As fisheries management shifts to an ecosystem-based approach, understanding energy pathways and trophic relationships in the Northern California Current (NCC) will become increasingly important for predictive modeling and understanding ecosystem response to changing ocean conditions. In the NCC, pelagic forage fishes are a critical link between seasonal and interannual variation in primary production and upper trophic groups. We compared diets among dominant forage fish (sardines, anchovies, herring, and smelts) in the NCC collected in May and June of 2011 and June 2012, and found high diet variability between and within species on seasonal and annual time scales, and also on decadal scales when compared to results of past studies conducted in the early 2000s. Copepoda were a large proportion by weight of several forage fish diets in 2011 and 2012, which differed from a preponderance of Euphausiidae found in previous studies, even though all years exhibited cool ocean conditions. We also examined diet overlap among these species and with co-occurring subyearling Chinook salmon and found that surf smelt diets overlapped more with subyearling Chinook diets than any other forage fish. Herring and sardine diets overlapped the most with each other in our interdecadal comparisons and some prey items were common to all forage fish diets. Forage fish that show plasticity in diet may be more adapted to ocean conditions of low productivity or anomalous prey fields. These findings highlight the variable and not well-understood connections between ocean conditions and energy pathways within the NCC.

Turbidity interferes with foraging success of visual but not chemosensory predators.

Science.gov (United States)

Lunt, Jessica; Smee, Delbert L

2015-01-01

Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator-prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs.

Pronounced Seasonal Changes in the Movement Ecology of a Highly Gregarious Central-Place Forager, the African Straw-Coloured Fruit Bat (Eidolon helvum.

Directory of Open Access Journals (Sweden)

Jakob Fahr

Full Text Available Straw-coloured fruit bats (Eidolon helvum migrate over vast distances across the African continent, probably following seasonal bursts of resource availability. This causes enormous fluctuations in population size, which in turn may influence the bats' impact on local ecosystems. We studied the movement ecology of this central-place forager with state-of-the-art GPS/acceleration loggers and concurrently monitored the seasonal fluctuation of the colony in Accra, Ghana. Habitat use on the landscape scale was assessed with remote sensing data as well as ground-truthing of foraging areas.During the wet season population low (~ 4000 individuals, bats foraged locally (3.5-36.7 km in urban areas with low tree cover. Major food sources during this period were fruits of introduced trees. Foraging distances almost tripled (24.1-87.9 km during the dry season population peak (~ 150,000 individuals, but this was not compensated for by reduced resting periods. Dry season foraging areas were random with regard to urban footprint and tree cover, and food consisted almost exclusively of nectar and pollen of native trees.Our study suggests that straw-coloured fruit bats disperse seeds in the range of hundreds of meters up to dozens of kilometres, and pollinate trees for up to 88 km. Straw-coloured fruit bats forage over much larger distances compared to most other Old World fruit bats, thus providing vital ecosystem services across extensive landscapes. We recommend increased efforts aimed at maintaining E. helvum populations throughout Africa since their keystone role in various ecosystems is likely to increase due to the escalating loss of other seed dispersers as well as continued urbanization and habitat fragmentation.

Pronounced Seasonal Changes in the Movement Ecology of a Highly Gregarious Central-Place Forager, the African Straw-Coloured Fruit Bat (Eidolon helvum).

Science.gov (United States)

Fahr, Jakob; Abedi-Lartey, Michael; Esch, Thomas; Machwitz, Miriam; Suu-Ire, Richard; Wikelski, Martin; Dechmann, Dina K N

2015-01-01

Straw-coloured fruit bats (Eidolon helvum) migrate over vast distances across the African continent, probably following seasonal bursts of resource availability. This causes enormous fluctuations in population size, which in turn may influence the bats' impact on local ecosystems. We studied the movement ecology of this central-place forager with state-of-the-art GPS/acceleration loggers and concurrently monitored the seasonal fluctuation of the colony in Accra, Ghana. Habitat use on the landscape scale was assessed with remote sensing data as well as ground-truthing of foraging areas. During the wet season population low (~ 4000 individuals), bats foraged locally (3.5-36.7 km) in urban areas with low tree cover. Major food sources during this period were fruits of introduced trees. Foraging distances almost tripled (24.1-87.9 km) during the dry season population peak (~ 150,000 individuals), but this was not compensated for by reduced resting periods. Dry season foraging areas were random with regard to urban footprint and tree cover, and food consisted almost exclusively of nectar and pollen of native trees. Our study suggests that straw-coloured fruit bats disperse seeds in the range of hundreds of meters up to dozens of kilometres, and pollinate trees for up to 88 km. Straw-coloured fruit bats forage over much larger distances compared to most other Old World fruit bats, thus providing vital ecosystem services across extensive landscapes. We recommend increased efforts aimed at maintaining E. helvum populations throughout Africa since their keystone role in various ecosystems is likely to increase due to the escalating loss of other seed dispersers as well as continued urbanization and habitat fragmentation.

Linking animal population dynamics to alterations in foraging behaviour

DEFF Research Database (Denmark)

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

Background/Question/Methods The survival of animal populations is strongly influenced by the individuals’ ability to forage efficiently, yet there are few studies of how populations respond when disturbances cause animals to deviate from their natural foraging behavior. Animals that respond...... that are increasingly exposed to noise from ships, wind turbines, etc. In the present study we investigate how the dynamics of the harbor porpoise population (Phocoena phocoena) in the inner Danish waters is influenced by disturbances using an agent- based simulation model. In the model animal movement, and hence...... the animals’ ability to forage efficiently and to sustain their energy intake, is influenced by noise emitted from wind turbines and ships. The energy levels in turn affect their survival. The fine-scale movements of the simulated animals was governed by a spatial memory, which allowed the model to produce...

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

Science.gov (United States)

Railsback, Steven F; Harvey, Bret C

2013-02-01

Many ecologists believe that there is a lack of foraging theory that works in community contexts, for populations of unique individuals each making trade-offs between food and risk that are subject to feedbacks from behavior of others. Such theory is necessary to reproduce the trait-mediated trophic interactions now recognized as widespread and strong. Game theory can address feedbacks but does not provide foraging theory for unique individuals in variable environments. 'State- and prediction-based theory' (SPT) is a new approach that combines existing trade-off methods with routine updating: individuals regularly predict future food availability and risk from current conditions to optimize a fitness measure. SPT can reproduce a variety of realistic foraging behaviors and trait-mediated trophic interactions with feedbacks, even when the environment is unpredictable. Copyright © 2012 Elsevier Ltd. All rights reserved.

Central-place foraging and ecological effects of an invasive predator across multiple habitats.

Science.gov (United States)

Benkwitt, Cassandra E

2016-10-01

Cross-habitat foraging movements of predators can have widespread implications for predator and prey populations, community structure, nutrient transfer, and ecosystem function. Although central-place foraging models and other aspects of optimal foraging theory focus on individual predator behavior, they also provide useful frameworks for understanding the effects of predators on prey populations across multiple habitats. However, few studies have examined both the foraging behavior and ecological effects of nonnative predators across multiple habitats, and none has tested whether nonnative predators deplete prey in a manner predicted by these foraging models. I conducted behavioral observations of invasive lionfish (Pterois volitans) to determine whether they exhibit foraging movements similar to other central-place consumers. Then, I used a manipulative field experiment to test whether their effects on prey populations are consistent with three qualitative predictions from optimal foraging models. Specifically, I predicted that the effects of invasive lionfish on native prey will (1) occur at central sites first and then in surrounding habitats, (2) decrease with increasing distance away from their shelter site, and (3) extend to greater distances when prey patches are spaced closer together. Approximately 40% of lionfish exhibited short-term crepuscular foraging movements into surrounding habitats from the coral patch reefs where they shelter during daylight hours. Over the course of 7 weeks, lionfish depleted native fish populations on the coral patch reefs where they reside, and subsequently on small structures in the surrounding habitat. However, their effects did not decrease with increasing distance from the central shelter site and the influence of patch spacing was opposite the prediction. Instead, lionfish always had the greatest effects in areas with the highest prey densities. The differences between the predicted and observed effects of lionfish

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

Directory of Open Access Journals (Sweden)

S. Asokan

2010-02-01

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

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

Science.gov (United States)

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

2014-01-01

Relationships between foraging habitat and reproductive success provide compelling evidence of the contribution of specific vegetative features to foraging habitat quality, a potentially limiting factor for many animal populations. For example, foraging habitat quality likely will gain importance in the recovery of the threatened red-cockaded woodpecker Picoides...

On-Farm Research on the Nutritive Value of Forages and the Status of Mineral Soils, Forages and Blood Sera of Cattle in Small-Holder of Kenya

International Nuclear Information System (INIS)

Kiragu, J.W.; Lokwaleput, I.; Mitaru, B.N; Taminga, S

1999-01-01

An on-farm survey was carried out to evaluate the nutritive value of the locally grown forages, the status of minerals in soils, forages and blood serum of cows and calves fed or grazed on these forages. The survey involves 55 smallholder farms practising zero- and grazing semi zero grazing dairy production systems in Bahati and Naivasha Divisions of Nakuru District. The samples of forage and crop residues and other feeds available at the farm level were analysed for dry matter (DM), crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF), total lash and minerals-Ca, P, Mg, Na and Cu. Soil samples were analysed for pH, organic matter, Ca, P, Mg, Na and Cu. Samples of blood serum collected from the cows and calves utilising these forages were analysed for macro-elements-Ca, P, Mg, Na and trace elements such as Cu. Growth and production performance of the animals on these farms was studied. The results indicated a wide variation in the concentration of minerals in soils on different farms. Available feeds in these farms consisted of pasture, Napier grass and crop residues such as maize stovers. Pasture grasses and other established forages were deficient in protein ( - 1s), Na (316-339 ppm) and Cu (65- 120ppm) indicating the importance of mineral supplementation. The effect of age of the animal was significant for Cu (P 12.5%) and low milk production (< 10 kg per day) and low fertility suggesting the importance of protein, energy and mineral supplementation on the smallholder dairy farms of Bahati and Naivasha, possibly with concentrates and legumes which are rich in protein energy and minerals

Chemical composition and ruminal nutrient degradability of fresh and ensiled amaranth forage.

Science.gov (United States)

Seguin, Philippe; Mustafa, Arif F; Donnelly, Danielle J; Gélinas, Bruce

2013-12-01

Amaranth is a crop with potential as a source of forage for ruminants that has not been well characterized. A study was conducted to determine the impact of ensiling on the nutritional quality and ruminal degradability of forage from two amaranth cultivars adapted to North America (i.e. Plainsman and D136). In particular, quantification and some microscopic characterization of oxalate found in amaranth were performed as it is an antiquality compound of concern. There were limited interactions between cultivars and ensiling for most variables. Differences in chemical composition between amaranth cultivars were also limited. Ensiling reduced non-structural carbohydrate and true protein contents. The proportion of acid detergent protein was high in fresh and ensiled forages of both cultivars (average of 177 g kg(-1) crude protein). Total oxalate content averaged 30 and 25 g kg(-1) in fresh and ensiled forages respectively. Ensiling reduced soluble oxalate content. Crystals observed in amaranth were calcium oxalate druses found mostly in idioblast cells in leaf mesophyll and parenchyma of primary and secondary veins. In situ ruminal degradability data indicated that both fresh and ensiled amaranth are highly degradable in the rumen. This study confirms that amaranth is a suitable forage for ruminant animals. Its chemical composition is comparable, for most variables, to that of other commonly used forage species. © 2013 Society of Chemical Industry.

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

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Meagan A. Simons

2018-02-01

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

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

Science.gov (United States)

Simons, Meagan A; Smith, Adam R

2018-01-01

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

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.

The Main Suppressing Factors of Dry Forage Intake in Large-type Goats

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Tran Van Thang

2012-03-01

Full Text Available In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to determine whether or not marked decreases in dry forage intake after 40 min of feeding are mainly caused by the two factors, that is, ruminal distension and increased plasma osmolality induced thirst produced by dry forage feeding. Six large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 2 to 6 years, weighing 85.1±4.89 kg were used in two experiments. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 am during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, saliva lost via the esophageal fistula was replenished by an intraruminal infusion of artificial parotid saliva (RIAPS in sham feeding conditions (SFC control, and the treatment was maintained under normal feeding conditions (NFC. In experiment 2, a RIAPS and non-insertion of a balloon (RIAPS-NB control was conducted in the same manner as the SFC control of experiment 1. The intraruminal infusion of hypertonic solution and insertion of a balloon (RIHS-IB treatment was carried out simultaneously to reproduce the effects of changing salt content and ruminal distension due to feed entering the rumen. The results of experiment 1 showed that due to the effects of multiple dry forage suppressing factors when feed boluses entered the rumen, eating rates in the NFC treatment decreased (p<0.05 after 40 min of feeding and cumulative dry forage intake for the 2 h feeding period reduced to 43.8% of the SFC control (p<0.01. The results of experiment 2 indicated that due to the two suppressing factors of ruminal distension and increased plasma osmolality induced thirst, eating rates in the RIHS-IB treatment were

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

African Journals Online (AJOL)

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

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

NARCIS (Netherlands)

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

2001-01-01

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

Foraging behavior, environmental parameters and nests development of Melipona colimana Ayala (Hymenoptera: Meliponini) in temperate climate of Jalisco, México.

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Macías-Macías, J O; Tapia-Gonzalez, J M; Contreras-Escareño, F

2017-01-01

Melipona colimana Ayala is an endemic species inhabiting temperate forests of pine and oak of south of Jalisco in Mexico. During a year, it was recorded every 15 days foraging activity, environmental parameters and the development of colonies of M. colimana in its wild habitat. For five minutes every hour from 7:00 to 21:00, the bees that entered and left the hive and bringing pollen and resin were registered. Every hour the relative humidity, temperature, wind speed and light intensity was recorded and related to foraging activity. Additionally, the weight of the colonies recently transferred to wooden boxes, the number of brood combs, honey pots and pollen were registered. The time of beginning and ending of the foraging activity differs from the reports of stingless bees of tropical weather and the same happens with the pollen collection. The environmental parameters that affect other tropical stingless bees in the foraging activity also affect M. colimana in temperate climate. It was determined that the major activity season and the presence of more pollen pots in the colony is from November through February, for what it could be the best time of the year for the division and obtainance of new colonies, while the critical period of minor activity and pollen flow was during rainy season. These data may be useful for the future sustainable use of this species in temperate climate.

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

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Alexandria Wenninger

2016-06-01

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

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

Science.gov (United States)

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

2016-04-01

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

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

DEFF Research Database (Denmark)

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

2018-01-01

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

Quantifying the effect of colony size and food distribution on harvester ant foraging.

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Tatiana P Flanagan

Full Text Available Desert seed-harvester ants, genus Pogonomyrmex, are central place foragers that search for resources collectively. We quantify how seed harvesters exploit the spatial distribution of seeds to improve their rate of seed collection. We find that foraging rates are significantly influenced by the clumpiness of experimental seed baits. Colonies collected seeds from larger piles faster than randomly distributed seeds. We developed a method to compare foraging rates on clumped versus random seeds across three Pogonomyrmex species that differ substantially in forager population size. The increase in foraging rate when food was clumped in larger piles was indistinguishable across the three species, suggesting that species with larger colonies are no better than species with smaller colonies at collecting clumped seeds. These findings contradict the theoretical expectation that larger groups are more efficient at exploiting clumped resources, thus contributing to our understanding of the importance of the spatial distribution of food sources and colony size for communication and organization in social insects.

Foraging dives by post-breeding northern pintails

Science.gov (United States)

Miller, Michael R.

1983-01-01

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

The role of foraging behaviour in the sexual segregation of the African elephant.

Science.gov (United States)

Shannon, Graeme; Page, Bruce R; Duffy, Kevin J; Slotow, Rob

2006-11-01

Elephants (Loxodonta africana) exhibit pronounced sexual dimorphism, and in this study we test the prediction that the differences in body size and sociality are significant enough to drive divergent foraging strategies and ultimately sexual segregation. Body size influences the foraging behaviour of herbivores through the differential scaling coefficients of metabolism and gut size, with larger bodied individuals being able to tolerate greater quantities of low-quality, fibrous vegetation, whilst having lower mass-specific energy requirements. We test two distinct theories: the scramble competition hypothesis (SCH) and the forage selection hypothesis (FSH). Comprehensive behavioural data were collected from the Pongola Game Reserve and the Phinda Private Game Reserve in South Africa over a 2.5-year period. The data were analysed using sex as the independent variable. Adult females targeted a wider range of species, adopted a more selective foraging approach and exhibited greater bite rates as predicted by the body size hypothesis and the increased demands of reproductive investment (lactation and pregnancy). Males had longer feeding bouts, displayed significantly more destructive behaviour (31% of observations, 11% for females) and ingested greater quantities of forage during each feeding bout. The independent ranging behaviour of adult males enables them to have longer foraging bouts as they experience fewer social constraints than females. The SCH was rejected as a cause of sexual segregation due to the relative abundance of low quality forage, and the fact that feeding heights were similar for both males and females. However, we conclude that the differences in the foraging strategies of the sexes are sufficient to cause spatial segregation as postulated by the FSH. Sexual dimorphism and the associated behavioural differences have important implications for the management and conservation of elephant and other dimorphic species, with the sexes effectively

Nutritional characteristics of forages from Niger

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F. Infascelli

2010-04-01

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

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

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Elaine S Leung

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

Effects of forage provision to dairy calves on growth performance and rumen fermentation: A meta-analysis and meta-regression.

Science.gov (United States)

Imani, M; Mirzaei, M; Baghbanzadeh-Nobari, B; Ghaffari, M H

2017-02-01

A meta-analysis of the potential effect of forage provision on growth performance and rumen fermentation of dairy calves was conducted using published data from the literature (1998-2016). Meta-regression was used to evaluate the effects of different forage levels, forage sources, forage offering methods, physical forms of starter, and grain sources on the heterogeneity of the results. We considered 27 studies that reported the effects of forage provision to dairy calves. Estimated effect sizes of forage were calculated on starter feed intake, average daily gain (ADG), feed efficiency (FE), body weight (BW), and rumen fermentation parameters. Intake of starter feed, ADG, BW, ruminal pH, and rumen molar proportion of acetate increased when supplementing forage but FE decreased. Heterogeneity (the amount of variation among studies) was significant for intake of starter feed, ADG, FE, final BW, and rumen fermentation parameters. Improving overall starter feed intake was greater in calves offered alfalfa hay compared with those offered other types of forages. During the milk feeding and overall periods, improving ADG was greater for calves fed a high level of forage (>10% in dry matter) compared with those fed a low level of forage (≤10% in dry matter) diets. The advantages reported in weight gain at a high level of forage could be due to increased gut fill. Improving overall ADG was lower for calves offered forages with textured starter feed compared with ground starter feed. The meta-regression analysis revealed that changes associated with forage provision affect FE differently for various forage sources and forage offering methods during the milk-feeding period. Forage sources also modulated the effect of feeding forage on ruminal pH during the milk-feeding period. In conclusion, forage has the potential to affect starter feed intake and performance of dairy calves, but its effects depend on source, level, and method of forage feeding and physical form of starter

Stable Isotopic Insights into the Foraging Ecology of an Endangered Marine Predator, the Hawaiian Petrel

Science.gov (United States)

Wiley, A. E.; Ostrom, P. H.; James, H. F.

2010-12-01

Seabirds play vital roles in their ecosystems, both as predators in their oceanic foraging grounds and conduits of marine nutrients to island nesting sites. Despite growing evidence that food availability limits seabird populations, characterization of the diet and even foraging locations of some seabird species remains elusive. Here, we use stable carbon (δ13C) and nitrogen (δ15N) isotopes to study the foraging ecology of an endangered and poorly known seabird, the Hawaiian petrel (Pterodroma sandwichensis). This species nests solely on the main Hawaiian Islands but forages widely across the NE Pacific, sometimes traveling over 10,000km on single foraging trips. δ13C and δ15N values vary with trophic level and at the base of food webs throughout the marine range of the Hawaiian petrel. Thus, we are able to use isotope signatures in modern and ancient petrel tissues to track spatial and temporal variation in foraging location and diet. We find strong evidence of foraging segregation between populations, with hatch-year birds from the island of Hawaii exhibiting feather δ15N and δ13C values over 3‰ and 1 ‰ higher, respectively, than those found in Maui and Kauai hatch-year birds. There is also significant variation in δ15N values between feathers from Kauai, Hawaii, and Maui adults, indicating additional foraging segregation during the winter molt. To distinguish between the effects of trophic level and foraging location, we relate our data to those from seabirds with known diet and foraging location, as well as to previous characterizations of isoscapes in the NE Pacific and at-sea observations of our study species. Finally, we track Hawaiian petrel foraging ecology back in time through examination of stable isotope values in historical feathers and ancient bone collagen. We find that, despite a species-wide decline in δ15N values (consistent with trophic level decline), populations have maintained divergent isotopic niches through at least the past 1

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

NARCIS (Netherlands)

Drent, J; Lichtenbelt, WDV; Wikelski, M

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

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

Forage seeding in rangelands increases production and prevents weed invasion

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Josh Davy

2017-07-01

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

A quantification of predation rates, indirect positive effects on plants, and foraging variation of the giant tropical ant, Paraponera clavata

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Lee A. Dyer

2002-09-01

Full Text Available While a clear consensus is emerging that predators can play a major role in shaping terrestrial communities, basic natural history observations and simple quantifications of predation rates in complex terrestrial systems are lacking. The potential indirect effect of a large predatory ant, Paraponera clavata Fabricius (Formicidae: Ponerinae, on herbivores was determined on rainforest trees at La Selva Biological Station in Costa Rica and Barro Colorado Island in Panama. Prey and other food brought back to nests by 75 colonies of P. clavata were quantified, taking into account temporal, seasonal, and microhabitat variation for both foraging activity and composition of foraging booty. The dispersion and density of ant colonies and combined density with the mean amounts of prey retrieval were used to calculate rates of predation per hectare in the two forests. In addition, herbivory was measured on trees containing P. clavata and on trees where the ants were not foraging. Colonies at La Selva brought back significantly more nectar plus prey than those at Barro Colorado Island, but foraging patterns were similar in the two forests. At both forests, the ants were more active at night, and there was no significant seasonal or colonial variation in consumption of nectar, composition of foraging booty, and overall activity of the colonies. At La Selva, trees containing P. clavata colonies had the same levels of folivory as nearest neighbor trees without P. clavata but had significantly lower folivory than randomly selected trees. Predation by this ant was high in both forests, despite its omnivorous diet. This insect predator is part of potentially important top-down controls in these wet and moist forests.

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

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Caroline L Poli

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

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

Science.gov (United States)

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

2017-01-01

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

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.

Maize forage aptitude: Combining ability of inbred lines and stability of hybrids

Directory of Open Access Journals (Sweden)

Luis Máximo Bertoia

2014-12-01

Full Text Available Breeding of forage maize should combine improvement achieved for grain with the specific needs of forage hybrids. Production stability is important when maize is used for silage if the planting area is not in the ideal agronomic environment. The objectives of the present research were: (i to quantify environmental and genetic and their interaction effects on maize silage traits; (ii to identify possible heterotic groups for forage aptitude and suggest the formation of potential heterotic patterns, and (iii to identify suitable inbred line combinations for producing hybrids with forage aptitude. Forty-five hybrids derived from diallelic crosses (without reciprocals among ten inbred lines of maize were evaluated in this study. Combined ANOVA over environments showed differences between genotypes (G, environments (E, and their interactions (GEI. Heritability (H2, and genotypic and phenotypic correlations were estimated to evaluate the variation in and relationships between forage traits. Postdictive and predictive AMMI models were fitted to determine the importance of each source of variation, G, E, and GEI, and to select genotypes simultaneously on yield, quality and stability. A predominance of additive effects was found in the evaluated traits. The heterotic pattern Reid-BSSS × Argentine flint was confirmed for ear yield (EY and harvest index (HI. High and broad genetic variation was found for stover and whole plant traits. Some inbred lines had genes with differential breeding aptitude for ear and stover. Stover and ear yield should be the main breeding objectives in maize forage breeding.

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

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.

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

Science.gov (United States)

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

2000-07-01

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

Foraging behavior of three passerines in mature bottomland hardwood forests during summer.

Energy Technology Data Exchange (ETDEWEB)

Buffington, J., Matthew; Kilgo, John, C.; Sargent, Robert, A.; Miller, Karl, V.; Chapman, Brian, R.

2001-08-01

Attention has focused on forest management practices and the interactions between birds and their habitat, as a result of apparent declines in populations of many forest birds. Although avian diversity and abundance have been studied in various forest habitats, avian foraging behavior is less well known. Although there are published descriptions of avian foraging behaviors in the western United States descriptions from the southeastern United States are less common. This article reports on the foraging behavior of the White-eyed Vireo, Northern Parula, and Hooded Warbler in mature bottomland hardwood forests in South Carolina.

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

Science.gov (United States)

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

2010-10-01

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

Effect of phenotypic residual feed intake and dietary forage content on the rumen microbial community of beef cattle.

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Carberry, Ciara A; Kenny, David A; Han, Sukkyan; McCabe, Matthew S; Waters, Sinead M

2012-07-01

Feed-efficient animals have lower production costs and reduced environmental impact. Given that rumen microbial fermentation plays a pivotal role in host nutrition, the premise that rumen microbiota may contribute to host feed efficiency is gaining momentum. Since diet is a major factor in determining rumen community structure and fermentation patterns, we investigated the effect of divergence in phenotypic residual feed intake (RFI) on ruminal community structure of beef cattle across two contrasting diets. PCR-denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) were performed to profile the rumen bacterial population and to quantify the ruminal populations of Entodinium spp., protozoa, Fibrobacter succinogenes, Ruminococcus flavefaciens, Ruminococcus albus, Prevotella brevis, the genus Prevotella, and fungi in 14 low (efficient)- and 14 high (inefficient)-RFI animals offered a low-energy, high-forage diet, followed by a high-energy, low-forage diet. Canonical correspondence and Spearman correlation analyses were used to investigate associations between physiological variables and rumen microbial structure and specific microbial populations, respectively. The effect of RFI on bacterial profiles was influenced by diet, with the association between RFI group and PCR-DGGE profiles stronger for the higher forage diet. qPCR showed that Prevotella abundance was higher (P < 0.0001) in inefficient animals. A higher (P < 0.0001) abundance of Entodinium and Prevotella spp. and a lower (P < 0.0001) abundance of Fibrobacter succinogenes were observed when animals were offered the low-forage diet. Thus, differences in the ruminal microflora may contribute to host feed efficiency, although this effect may also be modulated by the diet offered.

Microbial release of ferulic and p-coumaric acids from forages and their digestibility in lactating cows fed total mixed rations with different forage combinations.

Science.gov (United States)

Cao, Bin-Bin; Jin, Xin; Yang, Hong-Jian; Li, Sheng-Li; Jiang, Lin-Shu

2016-01-30

Ferulic acid (FA) and p-coumaric acid (PCA) are widely distributed in graminaceous plant cell walls. This study investigated the in vitro and in vivo digestibility of ester-linked FA (FAest) and PCA (PCAest) in lactating dairy cows. Regarding corn stover, ensiled corn stover, whole corn silage, Chinese wild ryegrass and alfalfa hay with different phenolic acid profiles, the in vitro rumen digestibility of forage FAest and PCAest was negatively correlated with the ether-linked FA content and original PCA/FA ratio in the forages. The concentration of both phenolic acids in culture fluids was low after a 72 h incubation, and the mixed rumen microorganisms metabolized nearly all phenolic acids released into the culture fluids. FAest digestibility in the whole digestive tract was negatively correlated with dietary PCA/FA ratio, but a converse result occurred with dietary PCAest digestibility. The digestibility in either the rumen or the whole digestive tract was greater for FAest than for PCAest. Forage PCAest in comparison with FAest is not easily digested in either the rumen or the whole digestive tract, and they were negatively affected by forage FAeth content and lignification extent indicated by the original dietary PCA/FA ratio. © 2015 Society of Chemical Industry.

Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants

International Nuclear Information System (INIS)

Peterson, Sarah H.; Peterson, Michael G.; Debier, Cathy; Covaci, Adrian; Dirtu, Alin C.; Malarvannan, Govindan; Crocker, Daniel E.; Schwarz, Lisa K.; Costa, Daniel P.

2015-01-01

As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N = 24), we satellite tracked and sampled the same seals before and after their approximately seven month long foraging trip. For males, we sampled different adults and sub-adults before (N = 14) and after (N = 15) the same foraging trip. For females, we calculated blubber burdens for all compounds. The highest POP concentrations in males and females were found for ∑ DDTs and ∑ PCBs. In blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females, ∑ DDT and ∑ PBDEs were highly correlated in blubber and serum. While ∑ PCBs were highly correlated with ∑ DDTs and ∑ PBDEs in blubber and serum for males, ∑ PCBs showed weaker correlations with both compounds in females. As females gained mass while foraging, concentrations of nearly all POPs in inner and outer blubber significantly decreased; however, the absolute burden in blubber significantly increased, indicating ingestion of contaminants while foraging. Additionally, we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences in ∑ DDTs, ∑ PBDEs, MeO-BDE 47, as well as the ratio of ∑ DDTs to ∑ PCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations of ∑ DDTs and ∑ PBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in 13 C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep

Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants

Energy Technology Data Exchange (ETDEWEB)

Peterson, Sarah H., E-mail: sarahpeterson23@gmail.com [Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060 (United States); Peterson, Michael G. [Department of Environmental Science, Policy and Management, University of California, Berkeley, 130 Mulford Hall, Berkeley, CA 94720 (United States); Debier, Cathy [Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 2/L7.05.08, 1348 Louvain-la-Neuve (Belgium); Covaci, Adrian [Toxicological Center, Campus Drie Eiken, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk (Belgium); Dirtu, Alin C. [Toxicological Center, Campus Drie Eiken, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk (Belgium); Department of Chemistry, “Al. I. Cuza” University of Iasi, 700506 Iasi (Romania); Malarvannan, Govindan [Toxicological Center, Campus Drie Eiken, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk (Belgium); Crocker, Daniel E. [Department of Biology, Sonoma State University, 1801 East Cotati Ave, Rohnert Park, CA 94928 (United States); Schwarz, Lisa K. [Institute of Marine Sciences, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060 (United States); Costa, Daniel P. [Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060 (United States)

2015-11-15

As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N = 24), we satellite tracked and sampled the same seals before and after their approximately seven month long foraging trip. For males, we sampled different adults and sub-adults before (N = 14) and after (N = 15) the same foraging trip. For females, we calculated blubber burdens for all compounds. The highest POP concentrations in males and females were found for ∑ DDTs and ∑ PCBs. In blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females, ∑ DDT and ∑ PBDEs were highly correlated in blubber and serum. While ∑ PCBs were highly correlated with ∑ DDTs and ∑ PBDEs in blubber and serum for males, ∑ PCBs showed weaker correlations with both compounds in females. As females gained mass while foraging, concentrations of nearly all POPs in inner and outer blubber significantly decreased; however, the absolute burden in blubber significantly increased, indicating ingestion of contaminants while foraging. Additionally, we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences in ∑ DDTs, ∑ PBDEs, MeO-BDE 47, as well as the ratio of ∑ DDTs to ∑ PCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations of ∑ DDTs and ∑ PBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in {sup 13}C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in

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

Science.gov (United States)

Suzuki, Toshitaka N; Kutsukake, Nobuyuki

2017-06-01

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

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...

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

African Journals Online (AJOL)

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

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

Science.gov (United States)

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

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

International Nuclear Information System (INIS)

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

2002-01-01

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

Cross-Cultural Consumer Acceptability and Purchase Intent of Forage-Finished Rib-Eye Steaks.

Science.gov (United States)

Torrico, Damir Dennis; Wardy, Wisdom; Pujols, Kairy Dharali; Carabante, Kennet Mariano; Jirangrat, Wannita; Scaglia, Guillermo; Janes, Marlene E; Prinyawiwatkul, Witoon

2015-10-01

Rib-eye steaks, from 3 forage-finished systems (S1, S2, and S3) and 1 commercial steak (C), either cooked by 1-sided-grilling or 2-sided-grilling, were evaluated for sensory acceptability [overall appearance (ORA) and overall appearance of fat (OAF) for raw steaks; overall appearance (OCA), overall beef aroma (OBA), overall beef flavor (OBF), juiciness, tenderness and overall liking (OL) for cooked steaks] and purchase intent by Hispanic, Asian and U.S. consumers. They also indicated preferred degree of doneness and cooking methods. Cross-cultural differences in preferences and consumer acceptability of rib-eye steaks were observed. Grilling was the most preferred cooking method. Hispanics and Asians preferred medium and/or medium well, while U.S. consumers preferred medium and/or medium rare. For cooked steaks, the population effect was significant for all sensory attributes; Asians generally scored lower than did Hispanics and U.S. consumers. C and S3 generally had higher scores for all sensory attributes across 3 populations. Purchase intent for all forage-finished steaks was higher for Hispanics and U.S. consumers compared to Asians (50.0% to 77.8% compared with 43.2% to 65.9%). Attributes influencing purchase intent of forage-finished steaks differed among populations: tenderness (odds ratio = 1.4) for Hispanics, OCA (odds ratio = 1.5) for Asians, and OBF (odds ratio = 1.3) for U.S. consumers. Overall, this study demonstrated that the type of forage-finished system and ethnic differences influenced sensory acceptability and purchase intent of forage-finished rib-eye steaks. Demand for forage-finished beef has increased worldwide due to its potential health benefits. Little is known regarding the cross-cultural effects on the consumer acceptance of forage-finished beef. We evaluated sensory acceptance and purchase intent of raw and cooked forage-finished rib-eye steaks using Hispanic, Asian, and U.S. (White and African American) populations. This study

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

Directory of Open Access Journals (Sweden)

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.

Boldness predicts an individual's position along an exploration-exploitation foraging trade-off.

Science.gov (United States)

Patrick, Samantha C; Pinaud, David; Weimerskirch, Henri

2017-09-01

Individuals do not have complete information about the environment and therefore they face a trade-off between gathering information (exploration) and gathering resources (exploitation). Studies have shown individual differences in components of this trade-off but how stable these strategies are in a population and the intrinsic drivers of these differences is not well understood. Top marine predators are expected to experience a particularly strong trade-off as many species have large foraging ranges and their prey often have a patchy distribution. This environment leads these species to exhibit pronounced exploration and exploitation phases but differences between individuals are poorly resolved. Personality differences are known to be important in foraging behaviour but also in the trade-off between exploration and exploitation. Here we test whether personality predicts an individual exploration-exploitation strategy using wide ranging wandering albatrosses (Diomedea exulans) as a model system. Using GPS tracking data from 276 wandering albatrosses, we extract foraging parameters indicative of exploration (searching) and exploitation (foraging) and show that foraging effort, time in patch and size of patch are strongly correlated, demonstrating these are indicative of an exploration-exploitation (EE) strategy. Furthermore, we show these are consistent within individuals and appear stable in the population, with no reproductive advantage. The searching and foraging behaviour of bolder birds placed them towards the exploration end of the trade-off, whereas shy birds showed greater exploitation. This result provides a mechanism through which individual foraging strategies may emerge. Age and sex affected components of the trade-off, but not the trade-off itself, suggesting these factors may drive behavioural compensation to maintain resource acquisition and this was supported by the evidence that there were no fitness consequence of any EE trait nor the trade

Nitrogen removal and nitrate leaching for forage systems receiving dairy effluent.

Science.gov (United States)

Woodard, Kenneth R; French, Edwin C; Sweat, Lewin A; Graetz, Donald A; Sollenberger, Lynn E; Macoon, Bisoondat; Portier, Kenneth M; Wade, Brett L; Rymph, Stuart J; Prine, Gordon M; Van Horn, Harold H

2002-01-01

Florida dairies need year-round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentrations in soil water below the rooting zone for two forage systems during four 12-mo cycles (1996-2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha(-1) per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha(-1) per cycle for the low loading rate, 528 kg ha(-1) for the medium rate, and 585 kg ha(-1) for the high. For the corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye system (CSR), N removals were 320 kg ha(-1) per cycle for the low rate, 327 kg ha(-1) for the medium, and 378 kg ha(-1) for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1-24.2 g kg(-1)) than in corn and forage sorghum (10.3-14.7 g kg(-1)). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO3(-)-N leaching. For CSR, NO3(-)-N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy dosure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO3(-)-N concentrations below the rooting zone.

Visual perception and social foraging in birds.

Science.gov (United States)

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

2004-01-01

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

Foraging strategies of Antarctic Fulmarine petrels

NARCIS (Netherlands)

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

2010-01-01

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

Primary versus secondary drivers of foraging activity in sandeel schools (Ammodytes tobianus)

DEFF Research Database (Denmark)

Deurs, Mikael van; Behrens, Jane; Warnar, Thomas

2011-01-01

to fishery biologists and has consequences for a wide range of predators ranging from birds and mammals to commercially important species. However, experimental studies that shed light on the primary drivers of foraging activity in fish are rare. In the present study, whole schools of sandeel (A. tobianus......The commercially and ecologically valuable sandeel (Ammodytes ssp.) make distinct vertical shifts between an inactive stage, during which they seek refuge in the sand, and a pelagic schooling stage, during which they forage. This characteristic discontinuous foraging pattern constitutes a challenge......) were caught in August in east Denmark (65A degrees 02'30N; 12A degrees 37'00E) and kept in large tanks in the laboratory. It was found that the amount of food ingested and memory of past days feeding history are primary drivers of foraging activity at the level of the entire school, whereas external...

Effects of natural and synthetic alarm pheromone and individual pheromone components on foraging behavior of the giant Asian honey bee, Apis dorsata.

Science.gov (United States)

Li, Jianjun; Wang, Zhengwei; Tan, Ken; Qu, Yufeng; Nieh, James C

2014-10-01

Social pollinators such as honey bees face attacks from predators not only at the nest, but also during foraging. Pollinating honey bees can therefore release alarm pheromones that deter conspecifics from visiting dangerous inflorescences. However, the effect of alarm pheromone and its chemical components upon bee avoidance of dangerous food sources remains unclear. We tested the responses of giant honey bee foragers, Apis dorsata, presented with alarm pheromone at a floral array. Foragers investigated the inflorescence with natural alarm pheromone, but 3.3-fold more foragers preferred to land on the 'safe' inflorescence without alarm pheromone. Using gas chromatography-mass spectrometry analysis, we identified eight chemical components in the alarm pheromone, of which three components (1-octanol, decanal and gamma-octanoic lactone) have not previously been reported in this species. We bioassayed six major compounds and found that a synthetic mixture of these compounds elicited behaviors statistically indistinguishable from responses to natural alarm pheromone. By testing each compound separately, we show that gamma-octanoic lactone, isopentyl acetate and (E)-2-decen-1-yl acetate are active compounds that elicit significant alarm responses. Gamma-octanoic lactone elicited the strongest response to a single compound and has not been previously reported in honey bee alarm pheromone. Isopentyl acetate is widely found in the alarm pheromones of sympatric Asian honey bee species, and thus alarmed A. dorsata foragers may produce information useful for conspecifics and heterospecifics, thereby broadening the effects of alarm information on plant pollination. © 2014. Published by The Company of Biologists Ltd.

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

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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.

Soil preparation and forage sowing time for crop-livestock integration in corn culture

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Luiz Fernando de Andrade Fritsch

2012-01-01

Full Text Available This work was carried out during the 2008/2009 crop season, in an Oxisol. It was used a split-plot arrangement design, with each plot corresponding to a different soil preparation system and each split-plot corresponding to a different sowing time of the forage Brachiaria brizantha Stapf. The soil preparation systems were: heavy harrowing (HH, disk plough (DP, chisel plough (CP and no-till (NT, and the forage sowing times were: 0, 8, 16 and 25 days after sowing (DAS of corn, arranged in 16 treatments with 3 replicates. The productive and vegetative characteristics of the corn were evaluated. Soil preparations have influenced plant height and the first ear height, with the highest value found for the heavy harrow treatment. Forage sowing time had no influence on vegetative characteristics of the corn and productive characteristics were not influenced by the soil preparations. The forage sowing time had influence on corn productivity, causing decrease in competition with corn forage from 5 DAS. The productivity was highly correlated with the number of grains per ear.

Forage Quality Determined by Botanic Species’ Contribution on Permanent Pastures

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Neculai Dragomir

2011-10-01

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

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

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

2013-05-14

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

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

African Journals Online (AJOL)

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

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

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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 ...

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.

Increased Foraging in Outdoor Organic Pig Production—Modeling Environmental Consequences

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Malene Jakobsen

2015-11-01

Full Text Available Consumers’ motivations for buying organic products include a wish of acquiring healthy, environmentally friendly products from production systems that also ensure a high level of animal welfare. However, the current Danish organic pig production faces important challenges regarding environmental impact of the system. High ammonia emissions arise from outdoor concrete areas with growing pigs and sows on pasture possess an increased risk of nitrogen (N leaching. Direct foraging in the range area is suggested as a way to improve the nutrient efficiency at farm level and to support a more natural behavior of the pig. Thus, by modeling, we investigated the environmental consequences of two alternative scenarios with growing pigs foraging in the range area and different levels of crops available for foraging—grass–clover or a combination of Jerusalem artichokes and lucerne. It was possible to have growing pigs on free-range without increasing N leaching compared to the current practice. The alternative system with Jerusalem artichokes and lucerne (high integration of forage showed the lowest carbon foot print with 3.12 CO2 eq kg−1 live weight pig compared to the current Danish pasture based system with 3.69 kg CO2 eq kg−1 live weight pig. Due to positive impact on soil carbon sequestration, the second alternative system based on grass-clover (low integration of forage showed a similar carbon foot print compared to current practice with 3.68 kg CO2 eq kg−1 live weight pig. It is concluded that in practice there is room for development of organic farming systems where direct foraging plays a central role.

Foraging flight distances of wintering ducks and geese: a review

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William P. Johnson

2014-12-01

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

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

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Raquel Santiago Barro

2012-07-01

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

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

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

2015-01-01

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

Does foraging performance change with age in female little penguins (Eudyptula minor?

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Ilka Zimmer

Full Text Available Age-related changes in breeding performance are likely to be mediated through changes in parental foraging performance. We investigated the relationship of foraging performance with age in female little penguins at Phillip Island, Australia, during the guard phase of the 2005 breeding season. Foraging parameters were recorded with accelerometers for birds grouped into three age-classes: (1 young, (2 middle age and (3 old females. We found the diving behaviour of middle-aged birds differed from young and old birds. The dive duration of middle age females was shorter than that of young and old birds while their dive effort (measure for dive and post-dive duration relation was lower than that of young ones, suggesting middle-aged birds were in better physical condition than other ones. There was no difference in prey pursuit frequency or duration between age classes, but in the hunting tactic. Females pursued more prey around and after reaching the maximum depth of dives the more experienced they were (old > middle age > young, an energy saving hunting tactic by probably taking advantage of up-thrust momentum. We suggest middle age penguins forage better than young or old ones because good physical condition and foraging experience could act simultaneously.

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

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

2011-08-23

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

Foraging behavior, environmental parameters and nests development of Melipona colimana Ayala (Hymenoptera: Meliponini in temperate climate of Jalisco, México

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J. O. Macías-Macías

Full Text Available Abstract Melipona colimana Ayala is an endemic species inhabiting temperate forests of pine and oak of south of Jalisco in Mexico. During a year, it was recorded every 15 days foraging activity, environmental parameters and the development of colonies of M. colimana in its wild habitat. For five minutes every hour from 7:00 to 21:00, the bees that entered and left the hive and bringing pollen and resin were registered. Every hour the relative humidity, temperature, wind speed and light intensity was recorded and related to foraging activity. Additionally, the weight of the colonies recently transferred to wooden boxes, the number of brood combs, honey pots and pollen were registered. The time of beginning and ending of the foraging activity differs from the reports of stingless bees of tropical weather and the same happens with the pollen collection. The environmental parameters that affect other tropical stingless bees in the foraging activity also affect M. colimana in temperate climate. It was determined that the major activity season and the presence of more pollen pots in the colony is from November through February, for what it could be the best time of the year for the division and obtainance of new colonies, while the critical period of minor activity and pollen flow was during rainy season. These data may be useful for the future sustainable use of this species in temperate climate.

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

DEFF Research Database (Denmark)

Visser, Andre W.; Fiksen, Ø.

2013-01-01

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

Stable isotopes (δ13C, δ15N combined with conventional dietary approaches reveal plasticity in central-place foraging behaviour of little penguins (Eudyptula minor

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Andre eChiaradia

2016-01-01

Full Text Available Marine top and meso predators like seabirds are limited by the need to breed on land but forage on limited or patchily distributed resources at sea. Constraints imposed by such central-place foraging behaviour change during breeding or even disappear outside the breeding period when there is no immediate pressure to return to a central place. However, central place foraging is usually factored as an unchanging condition in life history studies. Here we used little penguin Eudyptula minor, a resident bird with one of the smallest foraging range among seabirds, to examine the different degree of pressure/constraints of being a central-place forager. We combined data on isotopic composition (δ13C and δ15N, conventional stomach contents and body mass of little penguins breeding at Phillip Island, Australia over nine years (2003-11. We explored relationships between diet and body mass in each stage of the breeding season (pre-laying, incubation, guard, and post-guard in years of high and low reproductive success. Values of δ13C and δ15N as well as isotopic niche width had similar patterns among years, with less variability later in the season when little penguins shorten their foraging range at the expected peak of their central-place foraging limitation. Body mass peaked before laying and hatching in preparation for the energetically demanding periods of egg production and chick provisioning. An increase of anchovy and barracouta in the diet, two major prey for little penguins, occurred at the critical stage of chick rearing. These intra-annual trends could be a response to imposed foraging constraints as reproduction progresses, while inter-annual trends could reflect their ability to match or mismatch the high energy demanding chick rearing period with the peak in availability of high-quality prey such as anchovy. Our findings underline the key advantages of using a stable isotope approach combined with conventional dietary reconstruction to

Estimating Rangeland Forage Production Using Remote Sensing Data from a Small Unmanned Aerial System (sUAS)

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Liu, H.; Jin, Y.; Devine, S.; Dahlgren, R. A.; Covello, S.; Larsen, R.; O'Geen, A. T.

2017-12-01

California rangelands cover 23 million hectares and support a $3.4 billion annual cattle industry. Rangeland forage production varies appreciably from year-to-year and across short distances on the landscape. Spatially explicit and near real-time information on forage production at a high resolution is critical for effective rangeland management, especially during an era of climatic extremes. We here integrated a multispectral MicaSense RedEdge camera with a 3DR solo quad-copter and acquired time-series images during the 2017 growing season over a topographically complex 10-hectare rangeland in San Luis Obispo County, CA. Soil moisture and temperature sensors were installed at 16 landscape positions, and vegetation clippings were collected at 36 plots to quantify forage dry biomass. We built four centimeter-level models for forage production mapping using time series of sUAS images and ground measurements of forage biomass and soil temperature and moisture. The biophysical model based on Monteith's eco-physiological plant growth theory estimated forage production reasonably well with a coefficient of determination (R2) of 0.86 and a root-mean-square error (RMSE) of 424 kg/ha when the soil parameters were included, and a R2 of 0.79 and a RMSE of 510 kg/ha when only remote sensing and topographical variables were included. We built two empirical models of forage production using a stepwise variable selection technique, one with soil variables. Results showed that cumulative absorbed photosynthetically active radiation (APAR) and elevation were the most important variables in both models, explaining more than 40% of the spatio-temporal variance in forage production. Soil moisture accounted for an additional 29% of the variance. Illumination condition was selected as a proxy for soil moisture in the model without soil variables, and accounted for 18% of the variance. We applied the remote sensing-based models to map daily forage production at 30-cm resolution for the

Host Plants Affect the Foraging Success of Two Parasitoids that Attack Light Brown Apple Moth Epiphyas postvittana (Walker (Lepidoptera: Tortricidae.

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Yi Feng

Full Text Available The light brown apple moth, Epiphyas postvittana is a key pest of wine grapes in Australia. Two parasitoids, Dolichogenidea tasmanica and Therophilus unimaculatus, attack the larval stage of this pest. D. tasmanica is dominant in vineyards, whereas T. unimaculatus is mainly active in native vegetation. We sought to understand why they differ in their use of habitats. Plants are a major component of habitats of parasitoids, and herbivore-infested plants influence parasitoid foraging efficiency by their architecture and emission of volatile chemicals. We investigated how different plant species infested by E. postvittana could affect the foraging success of the two parasitoid species in both laboratory and field experiments. Four common host-plant species were selected for this study. In paired-choice experiments to determine the innate foraging preferences for plants, both parasitoid species showed differences in innate search preferences among plant species. The plant preference of D. tasmanica was altered by oviposition experience with hosts that were feeding on other plant species. In a behavioral assay, the two parasitoid species allocated their times engaged in various types of behavior differently when foraging on different plant species. For both parasitoids, parasitism on Hardenbergia violacea was the highest of the four plant species. Significantly more larvae dropped from Myoporum insulare when attacked than from the other three host-plant species, which indicates that parasitism is also affected by interactions between plants and host insects. In vineyards, parasitism by D. tasmanica was significantly lower on M. insulare than on the other three host-plant species, but the parasitism rates were similar among the other three plant species. Our results indicate that plants play a role in the habitat preferences of these two parasitoid species by influencing their foraging behavior, and are likely to contribute to their distributions

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

OpenAIRE

William E. Cooper

2003-01-01

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

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

Science.gov (United States)

Lee, Mark A

2018-03-17

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

Towards an assessment of on-farm niches for improved forages in Sud-Kivu, DR Congo

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Birthe K. Paul

2016-10-01

Full Text Available Inadequate quantity and quality of livestock feed is a persistent constraint to productivity for mixed crop-livestock farming in eastern Democratic Republic of Congo. To assess on-farm niches of improved forages, demonstration trials and participatory on-farm research were conducted in four different sites. Forage legumes included Canavalia brasiliensis (CIAT 17009, Stylosanthes guianensis (CIAT 11995 and Desmodium uncinatum (cv. Silverleaf, while grasses were Guatemala grass (Tripsacum andersonii, Napier grass (Pennisetum purpureum French Cameroon, and a local Napier line. Within the first six months, forage legumes adapted differently to the four sites with little differences among varieties, while forage grasses displayed higher variability in biomass production among varieties than among sites. Farmers’ ranking largely corresponded to herbage yield from the first cut, preferring Canavalia, Silverleaf desmodium and Napier French Cameroon. Choice of forages and integration into farming systems depended on land availability, soil erosion prevalence and livestock husbandry system. In erosion prone sites, 55–60%of farmers planted grasses on field edges and 16–30% as hedgerows for erosion control. 43% of farmers grew forages as intercrop with food crops such as maize and cassava, pointing to land scarcity. Only in the site with lower land pressure, 71% of farmers grew legumes as pure stand. When land tenure was not secured and livestock freely roaming, 75% of farmers preferred to grow annual forage legumes instead of perennial grasses. Future research should develop robust decision support for spatial and temporal integration of forage technologies into diverse smallholder cropping systems and agro-ecologies.

Shifts in North Sea forage fish productivity and potential fisheries yield

DEFF Research Database (Denmark)

Worsøe Clausen, Lotte; Rindorf, Anna; van Deurs, Mikael

2018-01-01

productivity. Furthermore, from an ecosystem-based fisheries management perspective, a link between functional complementarity and productivity, indicates that ecosystem resilience may decline with productivity. Based on this, we advise that system productivity, perhaps monitored as forage fish growth, becomes......1. Forage fish populations support large scale fisheries and are key components of marine ecosystems across the world, linking secondary production to higher trophic levels. While climate-induced changes in the North Sea zooplankton community are described and documented in literature......, the associated bottom-up effects and consequences for fisheries remain largely unidentified. 2. We investigated the temporal development in forage fish productivity and the associated influence on fisheries yield of herring, sprat, Norway pout and sandeel in the North Sea. Using principal component analysis, we...

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

Science.gov (United States)

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

2009-01-01

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

Colony Diet Influences Ant Worker Foraging and Attendance of Myrmecophilous Lycaenid Caterpillars

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Sebastian Pohl

2016-09-01

Full Text Available Foraging animals regulate their intake of macronutrients such as carbohydrates and proteins. However, regulating the intake of these two macronutrients can be constrained by the nutrient content of available food sources. Compensatory foraging is a method to adjust nutrient intake under restricted nutrient availability by preferentially exploiting food sources that contain limiting nutrients. Here we studied the potential for compensatory foraging in the dolichoderine ant Iridomyrmex mayri, which is commonly found in associations with caterpillars of the obligatorily ant-associated lycaenid butterfly Jalmenus evagoras. The caterpillars receive protection against predators and parasites, and reward the ants with nutritional secretions from specialized exocrine glands. These secretions contain a mixture of sugars and free amino acids, particularly serine. We tested the influence of nutrient-deficient diets on foraging patterns in I. mayri by recording the intake of test solutions containing single types of macronutrients during food preference tests. We also investigated the level of ant attendance on fifth instar J. evagoras caterpillars to evaluate how changes in diet influenced ant tending of caterpillars and foraging on their secretions. Foragers on a protein diet compensated for the nutritional deficit by increasing the intake of test solutions that contained sucrose, compared to their counterparts on a non-restricted diet. Ants on a sugar diet, however, did not show a corresponding increased consumption of test solutions containing the amino acid serine. Additionally, compared with their counterparts on a mixed diet, ants on limited nutrient diets showed an increase in the number of caterpillar-tending workers, suggesting that the caterpillars’ secretions are suitable to compensate for the ants’ nutritional deficit.

Roosting and foraging social structure of the endangered Indiana bat (Myotis sodalis.

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Alexander Silvis

Full Text Available Social dynamics are an important but poorly understood aspect of bat ecology. Herein we use a combination of graph theoretic and spatial approaches to describe the roost and social network characteristics and foraging associations of an Indiana bat (Myotis sodalis maternity colony in an agricultural landscape in Ohio, USA. We tracked 46 bats to 50 roosts (423 total relocations and collected 2,306 foraging locations for 40 bats during the summers of 2009 and 2010. We found the colony roosting network was highly centralized in both years and that roost and social networks differed significantly from random networks. Roost and social network structure also differed substantially between years. Social network structure appeared to be unrelated to segregation of roosts between age classes. For bats whose individual foraging ranges were calculated, many shared foraging space with at least one other bat. Compared across all possible bat dyads, 47% and 43% of the dyads showed more than expected overlap of foraging areas in 2009 and 2010 respectively. Colony roosting area differed between years, but the roosting area centroid shifted only 332 m. In contrast, whole colony foraging area use was similar between years. Random roost removal simulations suggest that Indiana bat colonies may be robust to loss of a limited number of roosts but may respond differently from year to year. Our study emphasizes the utility of graphic theoretic and spatial approaches for examining the sociality and roosting behavior of bats. Detailed knowledge of the relationships between social and spatial aspects of bat ecology could greatly increase conservation effectiveness by allowing more structured approaches to roost and habitat retention for tree-roosting, socially-aggregating bat species.

Comparison of in vitro and in situ methods in evaluation of forage digestibility in ruminants.

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Krizsan, S J; Nyholm, L; Nousiainen, J; Südekum, K-H; Huhtanen, P

2012-09-01

The objective of this study was to compare the application of different in vitro and in situ methods in empirical and mechanistic predictions of in vivo OM digestibility (OMD) and their associations to near-infrared reflectance spectroscopy spectra for a variety of forages. Apparent in vivo OMD of silages made from alfalfa (n = 2), corn (n = 9), corn stover (n = 2), grass (n = 11), whole crops of wheat and barley (n = 8) and red clover (n = 7), and fresh alfalfa (n = 1), grass hays (n = 5), and wheat straws (n = 5) had previously been determined in sheep. Concentrations of indigestible NDF (iNDF) in all forage samples were determined by a 288-h ruminal in situ incubation. Gas production of isolated forage NDF was measured by in vitro incubations for 72 h. In vitro pepsin-cellulase OM solubility (OMS) of the forages was determined by a 2-step gravimetric digestion method. Samples were also subjected to a 2-step determination of in vitro OMD based on buffered rumen fluid and pepsin. Further, rumen fluid digestible OM was determined from a single 96-h incubation at 38°C. Digestibility of OM from the in situ and the in vitro incubations was calculated according to published empirical equations, which were either forage specific or general (1 equation for all forages) within method. Indigestible NDF was also used in a mechanistic model to predict OMD. Predictions of OMD were evaluated by residual analysis using the GLM procedure in SAS. In vitro OMS in a general prediction equation of OMD did not display a significant forage-type effect on the residuals (observed - predicted OMD; P = 0.10). Predictions of OMD within forage types were consistent between iNDF and the 2-step in vitro method based on rumen fluid. Root mean square error of OMD was least (0.032) when the prediction was based on a general forage equation of OMS. However, regenerating a simple regression for iNDF by omitting alfalfa and wheat straw reduced the root mean square error of OMD to 0

Evaluation of new hybrid brachiaria lines in Thailand. 1. Forage production and quality

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Michael D. Hare

2015-05-01

Full Text Available Forty-three new hybrid bracharia lines were evaluated for forage accumulation and nutritive value in Northeast Thailand from 2006 to 2011 in experiments at 2 sites, using Mulato II hybrid brachiaria as a standard for comparison. The parameters evaluated were wet and dry season dry matter (DM accumulation, leaf:stem ratio, crude protein (CP concentration and fiber level [acid detergent fiber (ADF and neutral detergent fiber (NDF]. No lines consistently displayed superior dry season forage accumulation and leaf:stem ratio over Mulato II. In the wet seasons, 14 lines produced more DM than Mulato II but in only one wet season each. Mulato II produced forage with high leaf:stem ratio in all seasons. Many lines did have significantly higher CP concentrations and lower levels of ADF and NDF than Mulato II, but their forage accumulation and leaf:stem ratio were inferior. Four lines (BR02/1718, BR02/1752, BR02/1794 and BR02/0465 were granted Plant Variety Rights in 2011.Keywords: Cayman, Cobra, crude protein, dry matter yields, forage regrowth,  Mulato II.DOI: 10.17138/TGFT(383-93 

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

OpenAIRE

Lee, Mark

2017-01-01

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

Dynamic optimal foraging theory explains vertical migrations of bigeye tuna

DEFF Research Database (Denmark)

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

2016-01-01

Bigeye tuna are known for remarkable daytime vertical migrations between deep water, where food is abundant but the water is cold, and the surface, where water is warm but food is relatively scarce. Here we investigate if these dive patterns can be explained by dynamic optimal foraging theory...... behaves such as to maximize its energy gains. The model therefore provides insight into the processes underlying observed behavioral patterns and allows generating predictions of foraging behavior in unobserved environments...

Diallel analysis of maize hybrids for agronomic and bromatological forage traits

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Matheus Henrique Silveira Mendes

2015-05-01

Full Text Available The aim of this study was to evaluate a diallel of maize hybrids for traits related to forage production and nutritional value. Six commercial hybrids were used as parents. The crosses were made according to a complete diallel design, obtaining the F1 and reciprocal crosses. The evaluations were performed in the main and second crop seasons in the 2010/2011 crop year at the Center for Technological Development in Agriculture of the Federal University of Lavras, located in Lavras, Minas Gerais State, Brazil. The experimental precision indicated by the coefficient of variation was good for all the traits measured. Significant differences were not observed among the crosses for traits related to the nutritional value of the forage. For fresh matter yield and dehusked ear yield, the general combining ability (GCA and specific combining ability (SCA effects were significant. Sowing in the second crop season reduced the yield and nutritional value of the forage. The interaction among the crosses and sowing seasons was not significant. For the beginning of an intrapopulational breeding program, the parent BM 3061 stands out by showing high estimates of GCA for the grain and forage yields.

Methane Production of Different Forages in Ruminal Fermentation

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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.

Optimal resource allocation to survival and reproduction in parasitic wasps foraging in fragmented habitats.

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Eric Wajnberg

Full Text Available Expansion and intensification of human land use represents the major cause of habitat fragmentation. Such fragmentation can have dramatic consequences on species richness and trophic interactions within food webs. Although the associated ecological consequences have been studied by several authors, the evolutionary effects on interacting species have received little research attention. Using a genetic algorithm, we quantified how habitat fragmentation and environmental variability affect the optimal reproductive strategies of parasitic wasps foraging for hosts. As observed in real animal species, the model is based on the existence of a negative trade-off between survival and reproduction resulting from competitive allocation of resources to either somatic maintenance or egg production. We also asked to what degree plasticity along this trade-off would be optimal, when plasticity is costly. We found that habitat fragmentation can indeed have strong effects on the reproductive strategies adopted by parasitoids. With increasing habitat fragmentation animals should invest in greater longevity with lower fecundity; yet, especially in unpredictable environments, some level of phenotypic plasticity should be selected for. Other consequences in terms of learning ability of foraging animals were also observed. The evolutionary consequences of these results are discussed.

Fermentation of six different forages in the semi-continuous fermentation technique Caesitec.

Science.gov (United States)

Vosmer, J; Liesegang, A; Wanner, M; Zeyner, A; Suter, D; Hoelzle, L; Wichert, B

2012-10-01

The aim of the present study was to compare carbohydrate degradation of forages which store carbohydrates either predominantly as fructan or starch, in horses' hindgut. The effects of an abrupt change from hay-based feeding to green fodder-based feeding on the caecal flora were tested with the in vitro hindgut simulation technique 'Caesitec'. Six trials with different forages (English ryegrass, tall fescue, grass mixture-horses, grass mixture-cows, lucerne, white clover) were conducted. During a 4-day stabilisation period, samples were taken once a day before loading the fermenters with hay. After diet-change to forage-based feeding, samples were taken four times a day. Ammonia and pH-value were measured before and 1, 2 and 6 h after loading the 'Caesitec'. Gas formation was measured daily. Bacterial numbers, lactate and short chain fatty acids were detected at four time-points of each trial. The grass mixtures contained the highest amounts of fructan. The pH-values were in the physiological range from pH 6 up to 7 (6.58-6.83) by feeding all forages. Gas formation, anaerobic and aerobic bacterial numbers increased after diet change from hay to any forage. The maximum amount of fructan (3.75 g/kg) in swiss pasture did not cause a permanent pathological change in the hindgut-flora. © 2012 Blackwell Verlag GmbH.

Cumulative Effects of Foraging Behavior and Social Dominance on Brain Development in a Facultatively Social Bee (Ceratina australensis).

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Rehan, Sandra M; Bulova, Susan J; O'Donnell, Sean

2015-01-01

In social insects, both task performance (foraging) and dominance are associated with increased brain investment, particularly in the mushroom bodies. Whether and how these factors interact is unknown. Here we present data on a system where task performance and social behavior can be analyzed simultaneously: the small carpenter bee Ceratina australensis. We show that foraging and dominance have separate and combined cumulative effects on mushroom body calyx investment. Female C. australensis nest solitarily and socially in the same populations at the same time. Social colonies comprise two sisters: the social primary, which monopolizes foraging and reproduction, and the social secondary, which is neither a forager nor reproductive but rather remains at the nest as a guard. We compare the brains of solitary females that forage and reproduce but do not engage in social interactions with those of social individuals while controlling for age, reproductive status, and foraging experience. Mushroom body calyx volume was positively correlated with wing wear, a proxy for foraging experience. We also found that, although total brain volume did not vary among reproductive strategies (solitary vs. social nesters), socially dominant primaries had larger mushroom body calyx volumes (corrected for both brain and body size variation) than solitary females; socially subordinate secondaries (that are neither dominant nor foragers) had the least-developed mushroom body calyces. These data demonstrate that sociality itself does not explain mushroom body volume; however, achieving and maintaining dominance status in a group was associated with mushroom body calyx enlargement. Dominance and foraging effects were cumulative; dominant social primary foragers had larger mushroom body volumes than solitary foragers, and solitary foragers had larger mushroom body volumes than nonforaging social secondary guards. This is the first evidence for cumulative effects on brain development by

Evaluation des fluides de forage HP/HT pour forages profonds Evaluation of Hp/Ht Drilling Fluid Formulations for Deep Drilling

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Argillier J. F.

2006-11-01

nombre de boues à base d'eau. Les résultats font apparaître que la nature des composants de la formulation exerce une forte influence sur le comportement de la boue dans des conditions difficiles. Le choix approprié d'additifs, tels que viscosifiants et réducteurs de filtrat, peut limiter les risques inhérents aux conditions de forage difficiles. Deep well drilling require the development of drilling fluid formulations adapted to high formation temperatures : a major cause of problems is the thermal degradation of chemical additives used in water based formulations that often occurs while drilling high temperature wells. Such a degradation can lead to strong variations in rheological and filtration characteristics and loss of properties. Moreover, even if no degradation of components occurs, the viscosity of hydrosoluble polymer solutions commonly used in fluid formulations strongly decreases as temperature increases above 60°C (150°F. Another cause of problems that arise at high temperature when using water based muds is the gelation of clays used in the formulation. This induces a deep increase in formulation viscosity and pressure drop, in particular when setting back in operation. Different methodologies have been developed for studying the behaviour of water based muds under high pressure/high temperature conditions. They include:(1 laboratory scale experiments such as anaerobic stability of polymer solutions, rheological behaviour of clay suspensions under high pressure/high temperature conditions thus simulating gelification properties of clays at high temperature;studying drilling fluids under realistic bottom hole conditions that are temperatures up to 180°C (380°F, pressures up to 500 bar and shear rates up to 10,000 s to the power of (-1. Using this methodology different water based muds have been tested. The results show that the nature of the constituents used in the water based formulation strongly influences the mud behaviour under harsh

Foraging plasticity of breeding Northern Rockhopper Penguins, Eudyptes moseleyi, in response to changing energy requirements

KAUST Repository

Booth, Jenny Marie

2018-04-02

During the breeding season, seabirds must balance the changing demands of self- and off-spring provisioning with the constraints imposed by central-place foraging. Recently, it was shown that Northern Rockhopper Penguins at Tristan da Cunha in the South Atlantic Ocean switch diet from lower to higher trophic level prey throughout their breeding cycle. Here, we investigated if this switch is reflected in their foraging behaviour, using time-depth recorders to study the diving behaviour of 27 guard and 10 crèche birds during the breeding season 2010 at Tristan da Cunha and obtaining complementary stomach contents of 20 birds. While no significant effects of breeding stage were detected on any foraging trip or dive parameters, stage/prey had a significant effect on feeding dive parameters, with dive duration, bottom time, and maximum depth explaining the majority of the dissimilarity amongst categories. We verified the previously shown dietary shift from zooplankton and cephalopods during the guard stage to a higher-energy fish-based diet during the crèche stage, which was reflected in a change in dive behaviour from shorter, shallower to longer, deeper dives. This prey switching behaviour may reflect preferential selection to account for the increased physiological needs of chicks or simply mirror changes in local prey abundance. Nonetheless, we show that Northern Rockhopper Penguins demonstrate behavioural plasticity as a response to their changing energy requirements, which is a critical trait when living in a spatio-temporally heterogeneous environment. This ability is likely to be particularly important under extrinsic constraints such as long-term environmental change.

Plant Functional Traits Associated with Mycorrhizal Root Foraging in Arbuscular Mycorrhizal and Ectomycorrhizal Trees

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Eissenstat, D. M.; Chen, W.; Cheng, L.; Liu, B.; Koide, R. T.; Guo, D.

2016-12-01

Root foraging for nutrient "hot spots" is a key strategy by which some plants maximize nutrient gain from their carbon investment in root and mycorrhizal hyphae. Foraging strategies may depend on costs of root construction, with thick roots generally costing more per unit length than thin roots. Investment in mycorrhizal hyphae, which are considerably thinner than roots, may represent an alternative strategy for cost-effective nutrient foraging, especially for thick-root species. Type of mycorrhiza may matter, as ectomycorrhizal (EM) fungi are more associated with longer hyphae and ability to mineralize organic matter than arbuscular mycorrhizal (AM) fungi. Among AM trees in both subtropical forests in SE China and in temperate forests in central Pennsylvania, USA, we found that tree species with thin roots proliferated their roots in soil patches enriched with mineral nutrients to a greater extent than species with thick roots. In addition, thick-root species were consistently colonized more heavily with mycorrhizal fungi than thin root species, although nutrient addition tended to diminish colonization. In a common garden in central Pennsylvania of both AM and EM tree species, we found that nutrient patches enriched with organic materials resulted in greater root and mycorrhizal fungal proliferation compared to those enriched with inorganic nutrients and that thick-root species proliferated more with their mycorrhizal fungi whereas thin-root species proliferated more with their roots. We further examined with many more species, patterns of root and mycorrhizal fungal proliferation in organic-nutrient-enriched patches. Foraging precision, or the extent that roots or mycorrhizal hyphae grew in the enriched patch relative to the unenriched patch, was related to both root thickness and type of mycorrhiza. In both AM and EM trees, thick-root species were not selective foragers of either their roots or hyphae. In thin-root species, there was strong selectivity in

Deep diving odontocetes foraging strategies and their prey field as determined by acoustic techniques

Science.gov (United States)

Giorli, Giacomo

Deep diving odontocetes, like sperm whales, beaked whales, Risso's dolphins, and pilot whales are known to forage at deep depths in the ocean on squid and fish. These marine mammal species are top predators and for this reason are very important for the ecosystems they live in, since they can affect prey populations and control food web dynamics through top-down effects. The studies presented in this thesis investigate deep diving odontocetes. foraging strategies, and the density and size of their potential prey in the deep ocean using passive and active acoustic techniques. Ecological Acoustic Recorders (EAR) were used to monitor the foraging activity of deep diving odontocetes at three locations around the world: the Josephine Seamount High Sea Marine Protected Area (JHSMPA), the Ligurian Sea, and along the Kona coast of the island of Hawaii. In the JHSMPA, sperm whales. and beaked whales. foraging rates do not differ between night-time and day-time. However, in the Ligurian Sea, sperm whales switch to night-time foraging as the winter approaches, while beaked whales alternate between hunting mainly at night, and both at night and at day. Spatial differences were found in deep diving odontocetes. foraging activity in Hawaii where they forage most in areas with higher chlorophyll concentrations. Pilot whales (and false killer whales, clustered together in the category "blackfishes") and Risso's dolphins forage mainly at night at all locations. These two species adjust their foraging activity with the length of the night. The density and size of animals living in deep sea scattering layers was studied using a DIDSON imaging sonar at multiple stations along the Kona coast of Hawaii. The density of animals was affected by location, depth, month, and the time of day. The size of animals was influenced by station and month. The DIDSON proved to be a successful, non-invasive technique to study density and size of animals in the deep sea. Densities were found to be an

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

African Journals Online (AJOL)

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

Harvest-related edge effects on prey availability and foraging of hooded warblers in a bottomland hardwood forest.

Energy Technology Data Exchange (ETDEWEB)

John Kilgo

2005-04-20

The effects of harvest-created canopy gaps in bottomland hardwood forests on arthropod abundance and, hence, the foraging ecology of birds are poorly understood. I predicted that arthropod abundance would be high near edges of group-selection harvest gaps and lower in the surrounding forest, and that male Hooded Warblers (Wilsonia citrina) foraging near gaps would find more prey per unit time than those foraging in the surrounding forest. In fact, arthropod abundance was greater >100 m from a gap edge than at 0-30 m or 30-100 m from an edge, due to their abundance on switchcane (Arundinaria gigantea); arthropods did not differ in abundance among distances from gaps on oaks (Quercus spp.) or red maple (Acer rubrum). Similarly, Hooded Warbler foraging attack rates were not higher near gap edges: when foraging for fledglings, attack rate did not differ among distances from gaps, but when foraging for themselves, attack rates actually were lower 0-30 m from gap edges than 30-100 m or >100 m from a gap edge. Foraging attack rate was positively associated with arthropod abundance. Hooded Warblers apparently encountered fewer prey and presumably foraged less efficiently where arthropods were least abundant, i.e., near gaps. That attack rates among birds foraging for fledglings were not affected by distance from gap (and hence arthropod abundance) suggests that prey availability may not be limiting at any location across the forest, despite the depressing effects of gaps on arthropod abundance.

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

Science.gov (United States)

Buttemer, William A; Dawson, William R

1993-10-01

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

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

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Dowell Anthony C

2011-08-01

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

Alternatives for forage evaluation in ruminants

NARCIS (Netherlands)

Gosselink, J.M.J.

2004-01-01

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

Hidden Markov models: the best models for forager movements?

Science.gov (United States)

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

2013-01-01

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

Hidden Markov models: the best models for forager movements?

Directory of Open Access Journals (Sweden)

Rocio Joo

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

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 1. Feedlot performance, carcass quality, and production costs.

Science.gov (United States)

Berthiaume, R; Mandell, I; Faucitano, L; Lafrenière, C

2006-08-01

Forty Angus-cross steers were used to evaluate 5 beef cattle management regimens for their effect on growth performance, carcass characteristics, and cost of production. A 98-d growing phase was incorporated using grass silage with or without growth promotants (trenbolone acetate + estradiol implants, and monensin in the feed) or soybean meal. Dietary treatments in the finishing phase were developed, with or without addition of the same growth promotants, based on exclusive feeding of forages with minimal supplementation or the feeding of barley-based diets. Overall, ADG for animals treated with growth promotants or fed supplemented diets (soybean meal and barley) was increased (P forage produced a heavier HCW (P forage-fed, nonimplanted beef market would need to garner a 16% premium to be economically competitive with cattle finished conventionally.

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

Science.gov (United States)

Boyette, Adam H

2016-05-01

Few systematic studies of play in foragers exist despite their significance for understanding the breadth of contexts for human development and the ontogeny of cultural learning. Forager societies lack complex social hierarchies, avenues for prestige or wealth accumulation, and formal educational institutions, and thereby represent a contrast to the contexts of most play research. Analysis of systematic observations of children's play among Aka forest foragers (n = 50, ages 4-16, M = 9.5) and Ngandu subsistence farmers (n = 48, ages 4-16, M = 9.1) collected in 2010 illustrates that while play and work trade off during development in both groups, and consistent patterns in sex-role development are evident, Aka children engage in significantly less rough-and-tumble play and competitive games than children among their socially stratified farming neighbors. © 2016 The Authors. Child Development © 2016 Society for Research in Child Development, Inc.

Factors influencing local ecological knowledge of forage resources: Ethnobotanical evidence from West Africa's savannas.

Science.gov (United States)

Naah, John-Baptist S N; Guuroh, Reginald T

2017-03-01

Recording local ecological knowledge (LEK) is a useful approach to understanding interactions of the complex social-ecological systems. In spite of the recent growing interest in LEK studies on the effects of climate and land use changes, livestock mobility decisions and other aspects of agro-pastoral systems, LEK on forage plants has still been vastly under-documented in the West African savannas. Using a study area ranging from northern Ghana to central Burkina Faso, we thus aimed at exploring how aridity and socio-demographic factors drive the distributional patterns of forage-related LEK among its holders. With stratified random sampling, we elicited LEK among 450 informants in 15 villages (seven in Ghana and eight in Burkina Faso) via free list tasks coupled with ethnobotanical walks and direct field observations. We performed generalized linear mixed-effects models (aridity- and ethnicity-based models) and robust model selection procedures. Our findings revealed that LEK for woody and herbaceous forage plants was strongly influenced by the ethnicity-based model, while aridity-based model performed better for LEK on overall forage resources and crop-related forage plants. We also found that climatic aridity had negative effect on the forage-related LEK across gender and age groups, while agro- and floristic diversity had positive effect on the body of LEK. About 135 species belonging to 95 genera and 52 families were cited. Our findings shed more light on how ethnicity and environmental harshness can markedly shape the body of LEK in the face of global climate change. Better understanding of such a place-based knowledge system is relevant for sustainable forage plants utilization and livestock production. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

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Jade Vacquie-Garcia

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

Bat guilds, a concept to classify the highly diverse foraging and echolocation behaviors of microchiropteran bats

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Annette eDenzinger

2013-07-01

Full Text Available Throughout evolution the foraging and echolocation behaviors as well as the motor systems of bats have been adapted to the tasks they have to perform while searching and acquiring food. When bats exploit the same class of environmental resources in a similar way, they perform comparable tasks and thus share similar adaptations independent of their phylogeny. Species with similar adaptations are assigned to guilds or functional groups. Habitat type and foraging mode mainly determine the foraging tasks and thus the adaptations of bats. Therefore we use habitat type and foraging mode to define seven guilds. The habitat types open, edge and narrow space are defined according to the bats’ echolocation behavior in relation to the distance between bat and background or food item and background. Bats foraging in the aerial, trawling, flutter detecting, or active gleaning mode use only echolocation to acquire their food. When foraging in the passive gleaning mode bats do not use echolocation but rely on sensory cues from the food item to find it. Bat communities often comprise large numbers of species with a high diversity in foraging areas, foraging modes, and diets. The assignment of species living under similar constraints into guilds identifies pattern of community structure and helps to understand the factors that underlie the organization of highly diverse bat communities. Bat species from different guilds do not compete for food as they differ in their foraging behavior and in the environmental resources they use. However, sympatric living species belonging to the same guild often exploit the same class of resources. To avoid competition they should differ in their niche dimensions. The fine grain structure of bat communities below the rather coarse classification into guilds is determined by mechanisms that result in niche partitioning.

Foraging patch selection in winter: a balance between predation risk and thermoregulation benefit.

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Sara Villén-Pérez

Full Text Available In winter, foraging activity is intended to optimize food search while minimizing both thermoregulation costs and predation risk. Here we quantify the relative importance of thermoregulation and predation in foraging patch selection of woodland birds wintering in a Mediterranean montane forest. Specifically, we account for thermoregulation benefits related to temperature, and predation risk associated with both illumination of the feeding patch and distance to the nearest refuge provided by vegetation. We measured the amount of time that 38 marked individual birds belonging to five small passerine species spent foraging at artificial feeders. Feeders were located in forest patches that vary in distance to protective cover and exposure to sun radiation; temperature and illumination were registered locally by data loggers. Our results support the influence of both thermoregulation benefits and predation costs on feeding patch choice. The influence of distance to refuge (negative relationship was nearly three times higher than that of temperature (positive relationship in determining total foraging time spent at a patch. Light intensity had a negligible and no significant effect. This pattern was generalizable among species and individuals within species, and highlights the preponderance of latent predation risk over thermoregulation benefits on foraging decisions of birds wintering in temperate Mediterranean forests.

African Journal of Range and Forage Science

African Journals Online (AJOL)

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

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

Science.gov (United States)

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

2016-10-01

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

A new way of assessing foraging behaviour at the individual level using faeces marking and satellite telemetry.

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Marie-Andrée Giroux

Full Text Available Heterogeneity in foraging behaviour can profoundly influence ecological processes shaping populations. To scale-up from individual foraging behaviour to processes occurring at the population scale, one needs to sample foraging behaviour at the individual level, and over large temporal scales or during critical seasons known to influence life-history traits. We developed an innovative technique to monitor foraging behaviour at the individual level in secretive species, a technique that can be ultimately used to investigate the links between foraging behaviour and life-history traits. First, the technique used a novel approach, namely the combination of telemetry tracking and biomarking of faeces with food dyes to locate fresh signs of presence left by individuals equipped with GPS collars. Second, the technique is based on the simultaneous or successive sampling of life-history traits and individual foraging behaviour, using tracks with high probabilities of recovery of dyed faeces. We first describe our methodological approach, using a case study of a large herbivore, and then provide recommendations and guidelines for its use. Sampling single snow tracks of individuals equipped with a GPS collar was a reliable way to assess individual winter foraging behaviour in a white-tailed deer (Odocoileus virginianus Zimmermann population. During that period, the probability of recovery of dyed faeces within the range of the collar precision was very high for single snow tracks of equipped deer (97%. Our approach is well suited to study individual foraging behaviour, and could ultimately be used to investigate the interplay between intra-population heterogeneity in foraging behaviour, life-history traits, and demographic processes.

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

Science.gov (United States)

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

2018-04-02

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

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...

Forage Food of Timor Deer (Cervus timorensis in Manokwari, West Papua

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AYS Arobaya

2010-05-01

Full Text Available Traditionally, back yard deer husbandry is well developed in some parts in Papua, though information on deer husbandry has not been provided yet. Therefore, this study was aimed at highlighting the diet provided to the deer in back yard husbandry model in Manokwari. Survey method was approached by visiting eight deer back yard farmer respondents. Direct observation to the feeding site and semi-structured interview were carried out to learn about the deer management system, and identify the forage diet species consumed and served to the animals. The results indicated five most common forage species consumed in the study; they were field grass, Imperata (Imperata cylindrica, elephant grass (Penisetum purpureum, king grass (Penisetum purpureopoidhes and Melinis minutiflora depending on the location of farmed deer. Drinking water was offered and feed supplement such as various leafs, food and vegetable left over and banana peel was provided by 62.5% of the respondents. Food supplement was given two times per day (morning, evening and (afternoon, evening. Forage food species consumed in the study sites were relatively more similar to the food in the natural habitat. (Animal Production 12(2: 91-95 (2010Key Words: forage, food, Timor deer, Manokwari

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

Science.gov (United States)

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

2015-01-01

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

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

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Nobuo Kokubun

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

Do bigger bats need more time to forage?

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CEL. Esbérard

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

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

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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.

Testing forage legume technologies with smallholder dairy farmers ...

African Journals Online (AJOL)

Mo

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

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

NARCIS (Netherlands)

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

2012-01-01

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

Nitrogen Transfer to Forage Crops from a Caragana Shelterbelt

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Gazali Issah

2015-05-01

Full Text Available Caragana shelterbelts are a common feature of farms in the Northern Great Plains of North America. We investigated if nitrogen (N from this leguminous shrub contributed to the N nutrition of triticale and oat forage crops growing adjacent to the shelterbelt row. Nitrogen transfer was measured using 15N isotope dilution at distances of 2 m, 4 m, 6 m, 15 m and 20 m from the shelterbelt. At 2 m caragana negatively impacted the growth of triticale and oat. At 4 m from the shelterbelt productivity was maximum for both forage crops and corresponded to the highest amount of N originating from caragana. The amount of N transferred from caragana decreased linearly with distance away from the shelterbelt, but even at 20 m from the shelterbelt row measureable amounts of N originating from caragana were detectable in the forage biomass. At 4 m from the shelterbelt approximately 40% of the N in both oat and triticale was from caragana, and at 20 m from the shelterbelt approximately 20% of the N in oat and 8% of the N in triticale was from caragana.

Production of tropical forage grasses under different shading levels

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Francisco Eduardo Torres

2017-12-01

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

Effects of the juvenile hormone analogue methoprene on rate of behavioural development, foraging performance and navigation in honey bees (Apis mellifera).

Science.gov (United States)

Chang, Lun-Hsien; Barron, Andrew B; Cheng, Ken

2015-06-01

Worker honey bees change roles as they age as part of a hormonally regulated process of behavioural development that ends with a specialised foraging phase. The rate of behavioural development is highly plastic and responsive to changes in colony condition such that forager losses, disease or nutritional stresses accelerate behavioural development and cause an early onset of foraging in workers. It is not clear to what degree the behavioural development of workers can be accelerated without there being a cost in terms of reduced foraging performance. Here, we compared the foraging performance of bees induced to accelerate their behavioural development by treatment with the juvenile hormone analogue methoprene with that of controls that developed at a normal rate. Methoprene treatment accelerated the onset of both flight and foraging behaviour in workers, but it also reduced foraging span, the total time spent foraging and the number of completed foraging trips. Methoprene treatment did not alter performance in a short-range navigation task, however. These data indicate a limitation to the physiological plasticity of bees, and a trade off between forager performance and the speed at which bees begin foraging. Chronic stressors will be expected to reduce the mean age of the foraging force, and therefore also reduce the efficiency of the foraging force. This interaction may explain why honey bee colonies react to sustained stressors with non-linear population decline. © 2015. Published by The Company of Biologists Ltd.

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

NARCIS (Netherlands)

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

2008-01-01

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

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

NARCIS (Netherlands)

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

2018-01-01

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

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

OpenAIRE

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

2013-01-01

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

Performance and goats behavior in pasture of Andropogon grass under different forage allowances

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Daniel Louçana da Costa Araújo

2015-07-01

Full Text Available This study was accomplished to evaluate the behavior and performance of goats in to grazing on grass Andropogon gayanus Kunth var. Bisquamulatus (Hochst Hack. cv. Planaltina submitted to three forage allowances: 11, 15 and 19% BW/day, under continuous grazing. The experimental design to assess the grazing behaviour was randomized blocks in a split-plot with five replicates within the block. In the plots, we evaluated the effect of forage allowances and in the subplots, the months May and June. While for evaluation of animal performance was in complete block design with five replicates within the block. The different forage allowance did not cause structural changes in the pasture, except in height. However, there was an increase of dead material, leaf/stem ratio and reducing of height during the grazing period. The behavioral variables were not affected by forage allowance, except for the time of displacement, whereby goats spent more time in pastures with offer of 11% BW. The goats remained most part of the time in grazing and idle, corresponding to 89% and 5% of the evaluation time, respectively. Higher bit rate was observed in June, among the offerings, and 15 and 19% BW. The ingestive and grazing behaviour in goats is changed by the accumulation of dead material and stem in pasture from Andropogon grass during at rainy season. The forage supply 11% of BW increases the time of displacement of goats grazing on Andropogon grass. The management of grazing Andropogon grass with forage allowance being 11 and 19% of BW provides low weight gains in goats during the rainy season.

Effects of milk intake on forage intake and performance of suckling range calves.

Science.gov (United States)

Ansotegui, R P; Havstad, K M; Wallace, J D; Hallford, D M

1991-03-01

A study to examine the relationships between milk intake, forage intake, and performance of Hereford-Angus suckling range calves was conducted during July, August, and September of 1984 and 1985. Twenty calves were used each year. The study was conducted at the Red Bluff Research Ranch located 56 km west of Bozeman, Montana. Average daily gain, milk intake (MI), forage digestibility, and fecal output (FO) were measured at 28-d intervals, beginning when the average calf age was 66 +/- 4 d. Milk intake was estimated using weigh-suckle-weigh techniques. Total fecal collections were used to measure FO. Forage digestibility and rates of passage were determined using nylon bag in situ techniques and external markers in ruminally cannulated calves of the same age. Fecal output by calves increased as body weight and age increased. Milk intake was higher (P less than .05) in 1985 than in 1984, but FO was higher (P less than .01) in 1984 than in 1985. Fecal output by calves was negatively correlated to MI in July (r = -.62; P less than .05) and August (r = -.56; P less than .05). No significant correlations were detected between MI and ADG (P greater than .10). Forage intake estimates were derived from FO, rate of passage, and in situ digestibility values. During July, calves consumed .3 kg more forage for each kilogram of reduction in fluid MI (P less than .05). In both August and September, calves consumed .6 kg more forage for each kilogram of reduction in fluid MI (P less than .10). Calves maintained similar digestible energy (DE) intake both years, although the source of DE varied.

Movements and foraging effort of Steller's Eiders and Harlequin Ducks wintering near Dutch Harbor, Alaska

Science.gov (United States)

Reed, J.A.; Flint, Paul L.

2007-01-01

We studied the movements and foraging effort of radio-marked Steller's Eiders (Polysticta stelleri) and Harlequin Ducks (Histrionicus histrionicus) to evaluate habitat quality in an area impacted by industrial activity near Dutch Harbor, Alaska. Foraging effort was relatively low, with Steller's Eiders foraging only 2.7 ± 0.6 (SE) hours per day and Harlequin Ducks 4.1 ± 0.5 hours per day. Low-foraging effort during periods of high-energetic demand generally suggests high food availability, and high food availability frequently corresponds with reductions in home range size. However, the winter ranges of Harlequin Ducks did not appear to be smaller than usual, with the mean range size in our study (5.5 ± 1.1 km2) similar to that reported by previous investigators. The mean size of the winter ranges of Steller's Eiders was similar (5.1 ± 1.3 km2), but no comparable estimates are available. Eutrophication of the waters near Dutch Harbor caused by seafood processing and municipal sewage effluent may have increased populations of the invertebrate prey of these sea ducks and contributed to their low-foraging effort. The threat of predation by Bald Eagles (Haliaeetus leucocephalus) that winter near Dutch Harbor may cause Steller's Eiders and Harlequin Ducks to move further offshore when not foraging, contributing to an increase in range sizes. Thus, the movement patterns and foraging behavior of these ducks likely represent a balance between the cost and benefits of wintering in a human-influenced environment.

Foraging behaviour, nutrient intake from pasture and performance of free-range growing pigs in relation to feed CP level in two organic cropping systems

DEFF Research Database (Denmark)

Jakobsen, Malene; Kongsted, Anne Grete; Hermansen, John Erik

2015-01-01

In organic pig production one of the major challenges is to be able to fulfil amino acid requirements based on organic and locally grown protein feed crops. The pig is an opportunistic omnivore with a unique capacity for foraging above and below the soil surface. It is hypothesized that direct fo...

Environmental conditions and intraspecific interference: unexpected effects of turbidity on pike (Esox lucius) foraging

DEFF Research Database (Denmark)

Nilsson, P.A.; Jacobsen, Lene; Berg, Søren

2009-01-01

on pike foraging alone or among conspecifics in different levels of water turbidity, we expected high turbidity to decrease the perceived risk of intraspecific interactions among pike, and thereby decrease the strength of interference, as turbidity would decrease the visual contact between individuals...... and act as a refuge from behavioural interactions. The results show that this is not the case, but suggest that interference is induced instead of reduced in high turbidity. Per capita foraging rates do not differ between pike foraging alone or in groups in our clear and moderately turbid treatments......, indicating no effect of interference. As high turbidity enhances prey consumption for pike individuals foraging alone, but does not have this effect for pike in groups, high turbidity induces the relative interference effect. We suggest that future evaluations of the stabilizing effects of interference...

Improving tree establishment with forage crops

Science.gov (United States)

Eric J. Holzmueller; Carl W. Mize

2003-01-01

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

High precision during food recruitment of experienced (reactivated) foragers in the stingless bee Scaptotrigona mexicana (Apidae, Meliponini)

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Sánchez, Daniel; Nieh, James C.; Hénaut, Yann; Cruz, Leopoldo; Vandame, Rémy

Several studies have examined the existence of recruitment communication mechanisms in stingless bees. However, the spatial accuracy of location-specific recruitment has not been examined. Moreover, the location-specific recruitment of reactivated foragers, i.e., foragers that have previously experienced the same food source at a different location and time, has not been explicitly examined. However, such foragers may also play a significant role in colony foraging, particularly in small colonies. Here we report that reactivated Scaptotrigona mexicana foragers can recruit with high precision to a specific food location. The recruitment precision of reactivated foragers was evaluated by placing control feeders to the left and the right of the training feeder (direction-precision tests) and between the nest and the training feeder and beyond it (distance-precision tests). Reactivated foragers arrived at the correct location with high precision: 98.44% arrived at the training feeder in the direction trials (five-feeder fan-shaped array, accuracy of at least +/-6° of azimuth at 50 m from the nest), and 88.62% arrived at the training feeder in the distance trials (five-feeder linear array, accuracy of at least +/-5 m or +/-10% at 50 m from the nest). Thus, S. mexicana reactivated foragers can find the indicated food source at a specific distance and direction with high precision, higher than that shown by honeybees, Apis mellifera, which do not communicate food location at such close distances to the nest.

Retrospective analysis of bottlenose dolphin foraging: a legacy of anthropogenic ecosystem disturbance

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Rossman, Sam; Barros, Nélio B.; Ostrom, Peggy H.; Stricker, Craig A.; Hohn, Aleta A.; Gandhi, Hasand; Wells, Randall S.

2013-01-01

We used stable isotope analysis to investigate the foraging ecology of coastal bottlenose dolphins (Tursiops truncatus) in relation to a series of anthropogenic disturbances. We first demonstrated that stable isotopes are a faithful indicator of habitat use by comparing muscle isotope values to behavioral foraging data from the same individuals. δ13C values increased, while δ34S and δ15N values decreased with the percentage of feeding observations in seagrass habitat. We then utilized stable isotope values of muscle to assess temporal variation in foraging habitat from 1991 to 2010 and collagen from tooth crown tips to assess the time period 1944 to 2007. From 1991 to 2010, δ13C values of muscle decreased while δ34S values increased indicating reduced utilization of seagrass habitat. From 1944 to 1989 δ13C values of the crown tip declined significantly, likely due to a reduction in the coverage of seagrass habitat and δ15N values significantly increased, a trend we attribute to nutrient loading from a rapidly increasing human population. Our results demonstrate the utility of using marine mammal foraging habits to retrospectively assess the extent to which anthropogenic disturbance impacts coastal food webs.

How birds direct impulse to minimize the energetic cost of foraging flight

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Chin, Diana; Lentink, David

2017-11-01

Foraging arboreal birds frequently hop and fly between branches by extending long-jumps with a few wingbeats. Their legs transfer impulse to the branch during takeoff and landing, and their wings transfer impulse to the air to support their bodyweight during flight. To determine the mechanical energy tradeoffs of this bimodal locomotion, we studied how Pacific parrotlets transfer impulse during voluntary perch-to-perch flights. We tested five foraging flight variations by varying the inclination and distance between instrumented perches inside a novel aerodynamic force platform. This setup enables direct, time-resolved in vivo measurements of both leg and wing forces, which we combined with high-speed kinematics to develop a new bimodal long-jump and flight model. The model demonstrates how parrotlets direct their leg impulse to minimize the mechanical energy needed for each flight, and further shows how even a single proto-wingbeat would have significantly lengthened the long-jump of foraging arboreal dinosaurs. By directing jumps and flapping their wings, both extant and ancestral birds could thus improve foraging effectiveness. Similarly, bimodal robots could also employ these locomotion strategies to traverse cluttered environments more effectively.

Effect of season on the quality of forages selected by sheep in citrus plantations in Ghana

Directory of Open Access Journals (Sweden)

Leonard K. Adjorlolo

2014-09-01

Full Text Available The study aimed at assessing the effects of season on chemical composition of forages selected by sheep grazing in a citrus plantation. Forage species growing in a sweet orange (Citrus sinensis plantation were identified and sampled monthly for 2 years. Samples were bulked on monthly basis for chemical analysis. The average dry matter content of the forages increased from the rainy to the dry season but effects of season on the chemical components were inconsistent. Some species, such as Asystasia gangetica, had a higher crude protein concentration in the dry season, whereas for others, such as Panicum repens, the reverse occurred. However, average concentrations of crude protein, detergent fiber and components of fiber for all species for the rainy season were not significantly different from the dry season values. It was concluded that there were differences among forage species in their responses to changing seasons, such that grazing ruminants may select a diet to enable them to meet their nutritional requirements, provided forage biomass is adequate.Keywords: Crop-livestock integration, tree plantations, chemical composition, seasonal effects, forage quality.DOI: 10.17138/TGFT(2271-277

Metabolism and hindgut ecosystem in forage fed sedentary and athletic horses

OpenAIRE

Muhonen, Sara

2008-01-01

The objective of this thesis was to study the effects of forage crude protein content and forage conservation method on metabolism and hindgut ecosystem, abrupt feed changes and exercise response. In total 22 horses, both sedentary and athletic, were used. The sedentary horses were fistulated in right ventral colon and the athletic horses were in Standardbred race training. In the sedentary horses bacterial counts, volatile fatty acid (VFA), pH and dry matter (DM) in colon content and faeces ...

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

NARCIS (Netherlands)

Martin, Graham R.; Piersma, Theunis

2009-01-01

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

LivestockPlus: Forages, sustainable intensification, and food security in the tropics.

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Rudel, Thomas K; Paul, Birthe; White, Douglas; Rao, I M; Van Der Hoek, Rein; Castro, Aracely; Boval, Maryline; Lerner, Amy; Schneider, Laura; Peters, Michael

2015-11-01

The increased use of grain-based feed for livestock during the last two decades has contributed, along with other factors, to a rise in grain prices that has reduced human food security. This circumstance argues for feeding more forages to livestock, particularly in the tropics where many livestock are reared on small farms. Efforts to accomplish this end, referred to as the 'LivestockPlus' approach, intensify in sustainable ways the management of grasses, shrubs, trees, and animals. By decoupling the human food and livestock feed systems, these efforts would increase the resilience of the global food system. Effective LivestockPlus approaches take one of two forms: (1) simple improvements such as new forage varieties and animal management practices that spread from farmer to farmer by word of mouth, or (2) complex sets of new practices that integrate forage production more closely into farms' other agricultural activities and agro-ecologies.

The Effects of the Insect Growth Regulators Methoxyfenozide and Pyriproxyfen and the Acaricide Bifenazate on Honey Bee (Hymenoptera: Apidae) Forager Survival.

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Fisher, Adrian; Colman, Chet; Hoffmann, Clint; Fritz, Brad; Rangel, Juliana

2018-04-02

The honey bee (Apis mellifera L. (Hymenoptera: Apidae)) contributes an essential role in the U.S. economy by pollinating major agricultural crops including almond, which depends entirely on honey bee pollination for successful nut set. Almond orchards are often treated with pesticides to control a variety of pests and pathogens, particularly during bloom. While the effects to honey bee health of some insecticides, particularly neonicotinoids, have received attention recently, the impact of other types of insecticides on honey bee health is less clear. In this study, we examined the effects to honey bee forager survival of three non-neonicotinoid pesticides widely used during the 2014 California almond bloom. We collected foragers from a local apiary and exposed them to three pesticides at the label dose, or at doses ranging from 0.5 to 3 times the label dose rate. The selected pesticides included the insect growth regulators methoxyfenozide and pyriproxyfen, and the acaricide bifenazate. We simulated field exposure of honey bees to these pesticides during aerial application in almond orchards by using a wind tunnel and atomizer set up with a wind speed of 2.9 m/s. Experimental groups consisting of 30-40 foragers each were exposed to either untreated controls or pesticide-laden treatments and were monitored every 24 hr over a 10-d period. Our results revealed a significant negative effect of all pesticides tested on forager survival. Therefore, we suggest increased caution in the application of these pesticides in almond orchards or any agricultural crop during bloom to avoid colony health problems.

Examining short-term nutritional status among BaAka foragers in transitional economies.

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Remis, Melissa J; Jost Robinson, Carolyn A

2014-07-01

Foragers in transitioning economies are at an increased risk of negative health outcomes as they undergo changes in subsistence patterns and diet. Here, we provide anthropometric data and examine the nutrition and health of adult BaAka foragers in relationship to declining wildlife and economic change in the Dzanga Sangha Protected Areas (APDS), Central African Republic. From June to August 2012, we collected biological data and dietary recall surveys from individuals in Mossapoula (MS) and Yandoumbé (YDBE) villages using standard anthropometric techniques and a single capillary blood finger prick. In our analysis, we identified variation in anthropometric measurements and hemoglobin levels by village (MS = 66, YDBE = 75) and gender (64 men, 77 women). Immigration, increased gun hunting and wildlife trades have reduced forager reliance on forest resources. These changes are evidenced in the marginal health of contemporary BaAka foragers of APDS. Although anthropometric measures of nutritional status do not significantly differ between communities, hemoglobin data highlight inequities in access to forest products between villages with different proximity to community hunting zones. Further, poor dietary diversity and low frequency of purchased foods in the diet indicate that the transition to a market economy has not been fully realized and diets are impoverished. Economic changes appear to have had the most impact at MS village, where forest use is most restricted and consumption of meat and forest products was reduced. This work highlights the nutritional and health needs of foragers in rapidly transitioning economies; especially those impacted by conservation management and zoning policies. © 2014 Wiley Periodicals, Inc.

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

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Watson, James T; Haas, Randall

2017-09-01

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