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Moose (Alces alces) and woodland caribou (Ranger tarandus caribou) are the 2 large prey species for wolves (Canis lupus) in the Nearctic boreal forest in North America. Caribou have declined, with widespread anthropogenic disturbance as the ultimate cause and wolf predation as the proximal cause. To conserve caribou the government of Alberta, Canada initiated a wolf control program to reduce predation rates on caribou populations and contribute to caribou population recovery. Predators play an important role in shaping the structure and function of ecosystems through top‐down forces. We hypothesized that the strongest factors influencing moose occurrences would reflect changes in predation risk before and after the onset of wolf control. We weighed evidence for competing hypothesis by deploying cameras across a highly industrialized landscape in Alberta for 3 years after wolf control (2017–2020), capitalizing on 3 years of existing data before the onset of wolf control (2011–2014). We created generalized linear models representing competing hypotheses about moose response to natural and anthropogenic landscape features before and after wolf control, examining support for each in an information‐theoretic framework. Prior to wolf control, the model containing landscape features providing security cover was best‐supported, but this was scale‐dependent. After wolf control, the model containing landscape features that offer increased forage opportunities was best‐supported. Unexpectedly, the direction of effect was often opposite to predictions, with moose avoiding some features thought to provide security and forage. We demonstrate that lethal predator control affects the spatial distribution of its primary prey species but in ways we do not fully comprehend, highlighting the need for a better understanding of community dynamics following wolf control. [ABSTRACT FROM AUTHOR]

In a natural context, many avian species exhibit the ability to assess and balance factors such as food availability, food quality, and energy expenditure when making foraging decisions. However, avian behaviours can also diverge from the predictions, influenced by a range of variables, including social behaviours, predation pressures, and individual personalities. Chilean flamingos, popular social birds native to South America, remain relatively underexplored in terms of their foraging ecology and the interplay between environmental conditions and foraging behaviours, especially within the context of conservation. To address this knowledge gap, we conducted a comprehensive study, collecting monthly physical and biological data from foraging flocks of Chilean flamingos at Lagoa do Peixe National Park, a vital contra-nuptial site located in southern Brazil, spanning from October 2021 to September 2022. We employed Generalized Linear Mixed Models to establish correlations between this dataset and the relative frequency and duration of four identified foraging behaviours: Pecking up, Head-dipping, Feet-trembling, and Dredging. Our findings substantiate that the foraging patterns exhibited by Chilean flamingos in this region are intricately linked to the trade-off between energy expenditure and the rewards obtained, primarily influenced by factors such as lagoon depth and the availability of food resources. Moreover, our results unveil a parabolic pattern in the distances maintained between individual flamingos in the flock, potentially attributed to facilitate foraging dynamics within larger groups, despite the concurrent increase in aggressive interactions. In summary, our study underscores the multifaceted variables that influence the foraging strategies of Chilean flamingos in a significant contra-nuptial area in southern Brazil. It sheds light on the behavioural adaptability of these birds and underscores the potential repercussions of this dynamic on individual and population performance and fitness. • Water depth, food type and food availability are the main variables influencing the foraging behaviors of Chilean flamingo in a natural environment; • There are a trade-off between energetic reward and energetic expenditure while performing different foraging behaviors; • The intra-flock distance also influence the foraging behaviors characteristics, with a balance between intraspecific competition and foraging facilitation; [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are threatened by the introduction of invasive species. Generalist invaders often compete with native species for shared resources, resulting in possible native species niche displacement. However, environmental heterogeneity may modulate the level of individual specialisation in invasive species, altering the outcome of interspecific competition between invasive and native species. The objectives of our study were to (1) evaluate the environmental context of dietary specialisation and trophic position of an invasive species according to the Environmental Matching Hypothesis (EMH), and (2) consider how the environmental context of invasive species dietary resource use may influence the dietary niche of native species competing for similar resources.Resource use, trophic position and dietary niche were determined using gut content and stable isotope analyses for the invasive round goby (Negobius melanostomus) and the native yellow perch (Perca flavescens), along environmental gradients in an invaded fluvial ecosystem.Our results were in support of EMH for the invader diet and resource specialisation, but not trophic position. Under environmental conditions of high water‐conductivity, round gobies were generalists feeding mostly on pelagic prey. Under more challenging environmental conditions of low water‐conductivity, the invader specialised on preferred high‐quality benthic prey. The ecological impact of the round goby was greatest at low water‐conductivity sites where the invader was a benthic specialist; there was a greater relative dietary niche overlap between the invader and the native species.Our study uniquely illustrates how invasive species' resource specialisation can be modulated by spatial environmental heterogeneity within ecosystems, and how this can subsequently alter the ecological impact of the invader on native species in aquatic food webs. [ABSTRACT FROM AUTHOR]

Baiting is widely used in wildlife management for various purposes, including lethal control, fertility control, disease and parasite control, and conditioned aversion programs for many invasive vertebrate species. The efficacy of baiting programs relies on the likelihood that target animals will encounter the bait, consume it and receive an appropriate dose of the active ingredient. However, there has been little focus on encounter rate of toxic baits combined with behavioural aversion, which are likely to be significant factors affecting efficacy.Following optimal foraging theory, the likelihood of an animal encountering and consuming a toxic grain bait should increase in proportion to its availability relative to background food quantity if it is neither more or less detectable or palatable. Furthermore, the probability of consuming toxic baits might also be influenced by bait aversion following ingestion of a non‐lethal dose of toxin.Using a model system of wild house mice (Mus musculus L.) in mouse‐proof enclosures in Australia, we manipulated background food, applied zinc phosphide (Zn3P2) baits and measured mouse mortality. When background food was scarce, mouse mortality was high, whereas an increasing abundance of background food led to reduced mortality. A scenario modelling random encounters and including bait aversion explained 78% of the variation in observed mortality outcomes and achieved a closer fit to the data than modelling random encounters alone. Mortality rates were predicted to be higher with a higher strength bait, which would overcome behavioural aversion.Ensuring that animals locate and consume a lethal dose of toxic bait is a critical factor for successful bait delivery and efficacy. This is particularly significant in toxic baiting programs, where sublethal doses can make animals feel sick, leading to a negative association with the bait, and the development of aversion.Synthesis and applications: Our findings explain why some toxic baiting programs might fail. To achieve successful control, efforts should be directed at reducing the availability of background food to increase the probability of encounter and uptake of toxic baits. It is important to measure and understand the role of background food on toxic baiting programs to explain variable outcomes and inform strategies for successful bait delivery. [ABSTRACT FROM AUTHOR]

Optimal foraging and individual specialization theories suggest that different properties of the interactions between prey and predators determine foraging strategies. However, none of these theories consider how the nutritional status of the predators and the risk of being attacked by other predators may affect prey foraging strategy. Shelter-building spiders, such as Metazygia laticeps (Araneidae), build webs as dynamic traps to capture prey and may optimize capture efficiency while adopting strategies to minimize their exposure to predators by building a shelter and staying inside it most of the time. Prey capture, however, involves leaving the shelter, which may contribute to an increased risk of predation. Individuals may be more likely to take risks when they are in poor nutritional status. In this study, we conducted field experiments to assess support for the hypotheses that M. laticeps spiders with poor nutritional status (i) expose themselves to greater risk of predation during foraging and (ii) invest more silk in different web structures to increase prey capture success. Nutritional state was unrelated to exposure to predation and did not restrict web investment in M. laticeps. However, spiders left the shelter more quickly at night than during the day, regardless of their nutritional state. We suggest that individual's nutritional state does not determine foraging, and predation risk can affect general activity of spiders depending on foraging period. [ABSTRACT FROM AUTHOR]

ABSTRACT Optimal foraging theory (OFT) and the energy maximization hypothesis (EMH) have long been essential when examining wildlife habitat selection. At high latitudes and altitudes, animals in winter face greater limitations in availability and accessibility of forage. Here we explore the foraging behavior of wood bison (Bison bison athabascae) during winter within the Ronald Lake bison herd in northeastern Alberta, Canada, and examine the trade‐offs they face due to limitations in forage abundance and availability (snow conditions), as well as the need to minimize predation risk. We used Global Positioning System (GPS) location data collected from 70 female wood bison to identify winter foraging sites and craters selected by bison to access forage beneath the snow. Within wetlands used by bison we selected 190 pairs of used (foraged) and random (available) sites to test eight a priori hypotheses explaining how bison traded‐off between forage availability, accessibility, and minimizing predation risk. We found with matched‐paired logistic regression that Carex atherodes was 1.21‐times more likely to be selected per unit increase in ground cover, compared to 1.17‐times per unit ground cover for C. aquatilis and C. utriculata. However, all Carex species showed an increase in selection when cover was > 50% cover within individual craters. While the importance of Carex was clear, forage site selection was still inversely related to snow depth. There is also a neutralizing combined effect of snow depth and Carex species ground cover which suggests that bison maximized their energy return by avoiding areas with deep snow (> 30 cm) that demanded intensive cratering, even when highly selected forage was accessible beneath. Avoidance of forage areas with deep snow demonstrates that wood bison employed a foraging strategy that considers both forage availability and environmental conditions, with snow depth being a limiting factor. We highlight the relationship between optimal foraging based on food availability and the trade‐offs within an energy restrictive winter season, furthering the understanding of how large herbivores forage strategically to maximize energy intake in northern environments.

Prevailing theories about animal foraging behaviours and the food webs they occupy offer divergent predictions about whether seasonally limited food availability promotes dietary diversification or specialization. Emphasis on how animals compete for food predominates in work on the foraging ecology of large mammalian herbivores, whereas emphasis on how the diversity of available foods generally constrains dietary opportunity predominates work on entire food webs. Reconciling predictions about what promotes dietary diversification is challenging because species’ different body sizes and mobilities modulate how they seek and compete for resources—the mechanistic bases of common predictions may not pertain to all species equally. We evaluated predictions about five large-herbivore species that differ in body size and mobility in Yellowstone National Park using GPS tracking and dietary DNA. The data illuminated remarkably strong and significant correlations between body size and five key indicators of diet seasonality (R 2 = 0.71–0.80). Compared to smaller species, bison and elk showed muted diet seasonality and maintained access to more unique foods when winter conditions constrained food availability. Evidence from GPS collars revealed size-based differences in species’ seasonal movements and habitat-use patterns, suggesting that better accounting for the allometry of foraging behaviours may help reconcile disparate ideas about the ecological drivers of seasonal diet switching.

Parasites are omnipresent, and their eco‐evolutionary significance has aroused much interest from scientists. Parasites may affect their hosts in many ways with changes in density, appearance, behaviour and energy content, likely to modify their value to predators (profitability) within the optimal foraging framework. Consequently, parasites could impact predators' diet and the trophic links through food webs. Here, we investigate the consequences of the infection by the iridovirus Daphnia iridescent virus 1 (DIV‐1) on the reproductive success, mortality, appearance, mobility, and biochemical composition of water fleas Daphnia magna, a widespread freshwater crustacean. We do predation tests and compare search time, handling time and feeding preference between infected and uninfected Daphnia when preyed upon by Notonecta sp., a common aquatic insect. Our findings show that infection does not change fecundity but reduces lifespan and thereby constrains fitness. Infected Daphnia show reduced mobility and increased color reflectance in the UV and visible domains, which potentially affects their appearance and thus vulnerability to predators. Infection increases body size and the amount of proteins but does not affect carbohydrate and lipid contents. Although infected Daphnia are longer to handle, they are preferred over uninfected individuals by aquatic insects. Taken together, our findings show that DIV‐1 infection could make Daphnia more profitable to predators (24% energy increase), a positive effect that should be balanced with a lower availability due to the higher mortality of infected specimens. We also highlight that exposure to infection in asymptomatic individuals leads to ecological characteristics that differ from both healthy and symptomatic infected individuals. [ABSTRACT FROM AUTHOR]

Hyperparasitoids are ubiquitous components of terrestrial food webs. They must find their inconspicuous parasitoid host in a complex environment to generate offspring, but their foraging behaviour is poorly understood. Herbivore-induced plant volatiles (HIPVs) induced by parasitized caterpillars have been found to be exploited by hyperparasitoids in the cabbage system. However, the naturally occurring presence of nonhost organisms can interfere in HIPV production. It is unknown how hyperparasitoids respond to this source of variation in their foraging behaviour. We studied how the presence of nonhost herbivores affected foraging decisions of the hyperparasitoid Lysibia nana. In Y-tube olfactometer bioassays, we compared the preference of hyperparasitoids for volatiles from cabbage plants induced by single herbivory (host or nonhost), dual herbivory (host + nonhost) or uninfested cabbage plants. Following this, we conducted a common-garden experiment to study whether preferences observed in the laboratory are also apparent in the field. We found that L. nana preferred plants that were induced by its host, Cotesia glomerata -parasitized Pieris brassicae caterpillars. However, the volatiles of nonhost-induced plants hampered the hyperparasitoids' ability to locate host-induced plants in the Y-tube olfactometer. In particular, HIPVs induced by the nonhost caterpillar Mamestra brassicae in both single and dual herbivory hampered the hyperparasitoids' ability to locate host-induced plants. The presence of other nonhost herbivores feeding simultaneously on the same plants as host-containing herbivores did not interfere in L. nana's preference. In the field, hyperparasitoids could locate their host despite nonhost presence. Overall, these results indicate that host location errors by hyperparasitoids may occur during HIPV-guided foraging steps, which can be corrected by using more reliable cues after landing on the plant. This demonstrates the ability of higher trophic level organisms to exploit the scarce amount of available information to locate their host. • Nonhost herbivores interfered in HIPV-based host location of Lysibia nana. • Trait similarity between host and nonhost explained reduced host location. • HIPV-based host location errors were compensated for in the field. • Hyperparasitoids adjust their foraging strategy based on the most reliable cues. [ABSTRACT FROM AUTHOR]

Optimal Foraging Theory (OFT) predicts that a population's trophic niche expansion should occur in periods of food scarcity as individuals begin to opportunistically exploit sub‐optimal food items. However, the Niche Variation Hypothesis (NVH) posits that niche widening may result from increased among‐individual differentiation due to food partitioning to avoid competition. We tested these hypotheses through a DNA metabarcoding study of the Sardinian Warbler (Curruca melanocephala) diet over a year. We used null models and the decomposition of beta diversity on among‐individual dietary differentiation to infer the mechanisms driving the population's niche variation. Warblers fed frequently on berries, with a peak in late summer and, to a lesser extent, in autumn. Their diet also included a wide range of arthropods, with their prevalence varying among seasons. Consistent with OFT, the population's niche width was narrower in spring/summer when the population was strongly specialized in berries. In winter, the population's niche expanded, possibly reflecting seasonal declines in food abundance. As predicted by NVH, among‐individual differentiation tended to be higher in winter, but this was mainly due to increased differences in dietary richness rather than to the partitioning of resources. Overall, our results suggest that within‐individual niche does not increase in lean periods, and instead, individuals adopt either a more opportunistic or more specialized foraging strategy. Increased competition in periods of scarcity may help explain such patterns, but instead of showing increased food partitioning as expected from NVH, it may reflect OFT mechanisms on individuals with differential competitive ability to access better food resources. [ABSTRACT FROM AUTHOR]

Though herbivore grass dependence has been shown to increase with body size across herbivore species, it is unclear whether this relationship holds at the community level. Here we evaluate whether grass consumption scales positively with body size within African large mammalian herbivore communities and how this relationship varies with environmental context. We used stable carbon isotope and community occurrence data to investigate how grass dependence scales with body size within 23 savanna herbivore communities throughout eastern and central Africa. We found that dietary grass fraction increased with body size for the majority of herbivore communities considered, especially when complete community data were available. However, the slope of this relationship varied, and rainfall seasonality and elephant presence were key drivers of the variation—grass dependence increased less strongly with body size where rainfall was more seasonal and where elephants were present. We found also that the dependence of the herbivore community as a whole on grass peaked at intermediate woody cover. Intraspecific diet variation contributed to these community‐level patterns: common hippopotamus (Hippopotamus amphibius) and giraffe (Giraffa camelopardalis) ate less grass where rainfall was more seasonal, whereas Cape buffalo (Syncerus caffer) and savanna elephant (Loxodonta africana) grass consumption were parabolically related to woody cover. Our results indicate that general rules appear to govern herbivore community assembly, though some aspects of herbivore foraging behavior depend upon local environmental context. [ABSTRACT FROM AUTHOR]

Plants store chemical defenses that act as toxins against herbivores, such as toxic isothiocyanates (ITCs) in Brassica plants, hydrolyzed from glucosinolate (GLS) precursors. The fitness of herbivorous larvae can be strongly affected by these toxins, causing immature death. We modeled this phenomenon using a set of ordinary differential equations and established a direct relationship between feeding, toxin exposure, and the net energy of a larva, where the fitness of an organism is proportional to its net energy according to optimal foraging theory. Optimal foraging theory is widely used in ecology to model the feeding and searching behavior of organisms. Although feeding provides energy gain, plant toxins and foraging cause energy loss for the larvae. Our equations explain that toxin exposure and foraging can sharply reduce larval net energy to zero at an instar. Since herbivory needs energy, the only choice left for a larva is to stop feeding at that time point. If that is significantly earlier than the end of the last instar stage, the larva dies without food. Thus, we show that plant toxins can cause immature death in larvae from the perspective of optimal foraging theory. [ABSTRACT FROM AUTHOR]

Seed production and dispersal are crucial ecological processes impacting plant demography, species distributions and community assembly. Plant–animal interactions commonly mediate both seed production and seed dispersal, but current research often examines pollination and seed dispersal separately, which hinders our understanding of how pollination services affect downstream dispersal services. To fill this gap, we propose a conceptual framework exploring how pollen limitation can impact the effectiveness of seed dispersal for endozoochorous and myrmecochorous plant species. We summarize the quantitative and qualitative effects of pollen limitation on plant reproduction and use Optimal Foraging Theory to predict its impact on the foraging behaviour of seed dispersers. In doing so, we offer a new framework that poses numerous hypotheses and empirical tests to investigate links between pollen limitation and seed dispersal effectiveness and, consequently, post‐dispersal ecological processes occurring at different levels of biological organization. Finally, considering the importance of pollination and seed dispersal outcomes to plant eco‐evolutionary dynamics, we discussed the implications of our framework for future studies exploring the demographic and evolutionary impacts of pollen limitation for animal‐dispersed plants. [ABSTRACT FROM AUTHOR]

Increasing impacts of wildfire on arid regions of the world fuelled by climate change highlight the need to better understand how natural communities respond to fire. We took advantage of a large (1660‐km2) wildfire that erupted in northern California during an in‐progress study of black‐tailed deer (Odocoileus hemionus columbianus) to investigate deer use of and diets within burned and unburned habitats before and after the fire. We compared deer diet breadth to predictions of optimal foraging theory, the niche variation hypothesis, and opportunistic (i.e., generalist) foraging expectations under the assumption that overall availability and diversity of forage in burned areas declined immediately after the fire and increased as the plant community recovered in the next 3 years after the fire. We used faecal pellet counts to document space use and metabarcoding to study diet during pre‐fire, post‐fire, and recovery periods. Pellet counts supported predictions that deer increased use of unburned sites and reduced use of burn sites after the fire and began to return to burned sites in subsequent sampling years. Diet diversity did not differ significantly between control and burn sites before the fire, but was lower in burn than control sites post‐fire (p <.001), when and where diet was dominated by oak (Quercus spp). In contrast, during subsequent years, diet diversity was higher (including more herbaceous plants) in burn than control sites (p <.05). In contrast to predictions of optimal foraging and niche variation hypotheses, individual deer foraged as generalists for which changes in dietary niche breadth paralleled fire‐induced changes in diversity of the plant community. [ABSTRACT FROM AUTHOR]

Generalist species are core components of ecological networks and crucial for the maintenance of biodiversity. Generalist species and networks are expected to be more resilient, and therefore understanding the dynamics of specialization and generalization in ecological networks is a key focus in a time of rapid global change. Whilst diet generalization is frequently studied, our understanding of how it changes over time is limited. Here we explore temporal variation in diet specificity in the honeybee (Apis mellifera), using pollen DNA metabarcoding of honey samples, through the foraging season, over two years. We find that, overall, honeybees are generalists that visit a wide range of plants, but there is temporal variation in the degree of specialization. Temporal specialization of honeybee colonies corresponds to periods of resource limitation, identified as a lack of honey stores. Honeybees experience a lack of preferred resources in June when switching from flowering trees in spring to shrubs and herbs in summer. Investigating temporal patterns in specialization can identify periods of resource limitation that may lead to species and network vulnerability. Diet specificity must therefore be explored at different temporal scales in order to fully understand species and network stability in the face of ecological change. [ABSTRACT FROM AUTHOR]

Animals' diets reflect the morpho-physiological and behavioral responses used to obtain nutrients and energy. While optimal foraging theory predicts them in terms of food availability, the obligatory heat model (OHM) predicts them based on ambient temperature, which affects the activity and/or size of the digestive organs, influencing food digestibility. In the highlands of central-west Argentina, rodent diversity is dominated by Phyllotis vaccarum, Abrothrix andina, Akodon oenos, and Euneomys sp. that coexist in different sections of their elevational ranges. Although these species' diets are relatively flexible, it is unclear how temperature and food availability influence their constitution. To unveil this, we explored their feeding strategies at different elevations (1700, 2300, and 3100 m a.s.l.) and seasons (winter and spring-summer). By examining fecal samples, we quantified the intake of vegetative parts of plants, seeds, and arthropods. Abrothrix andina was insectivorous at 2300 m and omnivorous at 3100 m a.s.l. in line with the OHM predictions, suggesting a higher plant consumption derived from an increased capacity of digestive organs, favored by lower temperatures at higher elevations. Phyllotis vaccarum was herbivorous at all elevations, independently of food supply or temperature conditions. However, the secondary food choice occurred in line with the OHM predictions, suggesting a certain degree of digestive adjustment to ambient temperature. Akodon oenos, which was only captured at 2300 m, was insectivorous, whereas Euneomys sp., which was only present at 3100 m, was a specialist herbivore. We detected no seasonal variation in the feeding strategies of the rodents examined. Intraspecifically, thermoregulatory demands would influence the variation in feeding strategies at the elevational gradient, whereas nutritional requirements would explain their consistency between seasons. Interspecifically, we found that diet dissimilarity was relatively high, mainly at high elevations and during winter, which could facilitate species coexistence. [ABSTRACT FROM AUTHOR]

Prey ranking of animal resources is critical to the evaluation of decision-making of past foragers. Previous work in Central Western Argentina (CWA) has used a ranking of resources on the basis of size and weight alone. Here we present the first CWA resource ranking that incorporates handling costs. Our ranking puts the guanaco (Lama guanicoe) in first place, followed by Rheidae eggs and armadillos (Dasypodidae), and highlights the importance of certain resources commonly assumed to be low-ranking. Following the optimal foraging theory, we develop the diet-breath model (DBM) for two of the most representative environments of North Patagonia: the Monte and Patagonian deserts. The higher encounter rates with the first-ranked prey, guanaco, in the Patagonia desert, discourages the incorporation of lower-ranking resources into the diet. In contrast, lower guanaco encounter rates in the Monte desert favors a wider optimal diet model, including the incorporation of fish (i.e., Percichthys trucha). The DBM was used to (re)interpret temporal trends in human subsistence and to support the idea of an expansion of the diet during the Late Holocene in CWA. In general terms, the DBM expectations are confirmed with the regional zooarchaeological record. [ABSTRACT FROM AUTHOR]

Natural selection favours animals that forage more efficiently, such as those finding food faster, choosing better patches or increasing their rate of energy gain. Indeed, foraging behaviour has an effect on fitness, with better foragers producing more offspring. However, the evolution of foraging behaviour and its consequences on reproductive success has usually been tested in one generation only and the quantitative effects on fitness are not always measured. Here we artificially selected Drosophila melanogaster adults for their ability to find food quickly in a simple maze and measured the effect of this selection on their fitness. We tested two treatments, with four selected and two control independent replicates: i) selected flies, which were the fastest to find a food source inside a maze, and ii) control flies, which were randomly selected regarding their location in the maze. Fitness was calculated measuring fecundity and offspring survivorship. Our results show that after five generations, flies selected for better foraging found food two times faster than control flies. Additionally, selected flies had higher fitness than control flies, mainly because of greater fecundity in females during the first generation. These results show that foraging behaviour has a strong response to selection in few generations and that selection on foraging ability can have a correlated positive effect on fitness, nevertheless, this response is diluted over generations possibly due to the negative effect associated with the selection process. Significant statement: Natural selection favours animals that forage more efficiently, such as those finding food faster. However, most of the literature measuring the relationship between foraging efficiency and fitness usually only measures the effects in the first generation. In an experiment, we artificially selected Drosophila adult flies that found food faster in a simple maze and we also measured the fecundity and offspring survivorships in selected and non-selected flies. After five generations, the selected flies found food 2.46 times faster than their F1 (founding population) and the control flies that were not selected. Fecundity was higher for selected flies only in the first generation, correlation that was lost as the generations passed. These results show that foraging behaviour has a strong response to selection in a few generations and that the possible correlated positive effects on fitness are diluted over generations. [ABSTRACT FROM AUTHOR]

Ant foragers provide food to the rest of the colony, often requiring transport over long distances. Foraging for liquid is challenging because it is difficult to transport and share. Many social insects store liquids inside the crop to transport them to the nest, and then regurgitate to distribute to nest-mates through a behaviour called trophallaxis. Some ants instead transport fluids with a riskier behaviour called pseudotrophallaxis—holding a drop of liquid between the mandibles through surface tension. Ants share this droplet with nest-mates without ingestion or regurgitation. We hypothesised that ants optimize their liquid-collection approach depending on viscosity. Using an ant that employs both trophallaxis and pseudotrophallaxis, we investigated the conditions where each liquid-collection behaviour is favoured by measuring biophysical properties, collection time and reaction to food quality for typical and viscosity-altered sucrose solutions. We found that ants collected more liquid per unit time by mandibular grabbing than by drinking. At high viscosities ants switched liquid collection method to mandibular grabbing in response to viscosity and not to sweetness. Our results demonstrate that ants change transport and sharing methods according to viscosity–a natural proxy for sugar concentration–thus increasing the mass of sugar returned to the nest per trip. [ABSTRACT FROM AUTHOR]

Pumas (Puma concolor) are solitary large carnivores that exhibit high energetic investments while hunting prey that often take multiple days to consume. Therefore, pumas should behave in a way to maximize their energetic gains, including using caching, which is a behavior used by many mammal species to preserve and store food or to conceal it from conspecifics and scavengers to limit their losses. Yet pumas do not always cache their kills. In order to understand caching behavior, we used variables associated with the kills such as prey mass, search time, climate, and habitat to test 20 ecological models (representing four a priori hypotheses: food perishability, resource pulse, consumption time, and kleptoparasitism deterrence) in an information-theoretic approach of model selection to explore factors related to the caching behavior. Models were run with information from tracked radio-collared pumas in California over a 2.5-year period and identified a total of 352 kills. Overall, we documented pumas caching 61.5% of their kills, including 71.6% of Black-tailed Deer (Odocoileus hemionus columbianus), their primary prey in the study area. The model with a quadratic effect of adjusted mass of prey on puma caching probability had all of the empirical support (w = 1.00). Specifically, pumas were most likely to cache intermediate-sized prey, such as yearling and adult female deer, and also fed from cached kills for longer periods of time. Larger prey may be too large to easily cache, making it less energetically efficient—while small prey can often be consumed quickly enough to not require caching. This suggests that intermediate-sized prey may be the optimal size for caching, allowing a puma to feed for multiple days while not greatly increasing energetic output. The hypotheses we tested were not mutually exclusive and pumas caching their prey may occur for several reasons; nevertheless, our study demonstrated that pumas use caching to extend their foraging time and maximize energetic gains when preying on intermediate-sized prey. [ABSTRACT FROM AUTHOR]

Abstract Within optimal foraging theory animals should maximize their net energy gain while minimizing energetic costs. Energetic expenditure in wild animals is therefore key to measure proxies of fitness. Accelerometers are an effective tool to study animal movement-based energetics, but retrieval of the device is usually required and often difficult. Accelerometers measure movement across three axes (x, y, and z) and can be calibrated to measures of oxygen consumption from captive animals, providing estimates of overall energy expenditure. Measuring energetic expenditures using a global positioning system (GPS) approach could provide an alternative method to study energetic ecology. This technique uses locomotor speeds across a range of slopes from successive GPS locations, which can be linked to the energy expenditure from captive individuals. We compared accelerometer and GPS methods of energetic expenditures in free-roaming brown bears (Ursus arctos) on the Kodiak Archipelago, Alaska, USA. We then applied the GPS method to examine how multiple factors influenced brown bear movement-based daily energetic expenditures (MDEE). We found that while the two energetic measurements differed (Wilcoxon signed rank test: V = 2116, p

Early‐life conditions can have long‐term fitness consequences. However, it is still unclear what optimal rearing conditions are, especially for long‐lived carnivores. A more diverse diet ('balanced diet') might optimize nutrient availability and allow young to make experiences with a larger diversity of prey, whereas a narrow diet breadth ('specialized diet') might result in overall higher energy net gain. A diet that is dominated by a specific prey type (i.e. fish, 'prey type hypothesis') might be beneficial or detrimental, depending for example, on its toxicity or contaminant load.Generalist predators such as the white‐tailed eagle Haliaeetus albicilla provide an interesting possibility to examine the relationship between early life diet and long‐term offspring survival. In the Åland Islands, an archipelago in the Baltic Sea, white‐tailed eagles live in various coastal habitats and feed on highly variable proportions of birds and fish.We use data from 21,116 prey individuals that were collected from 120 territories during the annual surveys, to examine how early‐life diet is associated with apparent annual survival of 574 ringed and molecular‐sexed eaglets. We supplement this analysis by assessing the relationships between diet, reproductive performance and nestling physical condition, to consider whether they are confounding with possible long‐term associations.We find that early‐life diet is associated with long‐term fitness: Nestlings that are fed a diverse diet are in lower physical condition but have higher survival rates. Eagles that are fed more fish as nestlings have lower survival as breeding‐age adults, but territories associated with fish‐rich diets have higher breeding success.Our results show that young carnivores benefit from a high diversity of prey in their natal territory, either through a nutritional or learning benefit, explaining the higher survival rates. The strong relationship between early‐life diet and adult survival suggests that early life shapes adult foraging decisions and that eating fish is associated with high costs. This could be due to high levels of contaminants or high competition for fish‐rich territories. Long‐lasting consequences of early‐life diet are likely not only limited to individual‐level consequences but have the potential to drive eco‐evolutionary dynamics in this population. [ABSTRACT FROM AUTHOR]

Research in primate nutritional ecology uses concepts of quality, preference, and energy content to explain food choice: a primate consumes high-quality, preferred, and/or high-energy foods when available, and moves to other foods when they are not. Many frugivorous primates are thought to maximize energy, suggesting that high-energy fruit is a quality/preferred resource. However, recent research suggests a more complicated picture, including nutrient balancing and state-dependent foraging decisions. This brings into question whether a food is inherently high- or low-quality or whether this depends on previous feeding choices of the consumer. We tested whether a frugivorous primate, Pongo pygmaeus wurmbii, selects nonfruit foods when fruit is available. To test selectivity, we looked for three behaviors: (1) orangutans leaving available fruit for nonfruit foods, (2) evidence of orangutans navigating to nonfruit foods, and (3) orangutans selecting nonfruit when fruit was available and nearby. We use data from 51 focal follows (611 feeding bouts, 15 animals) in Gunung Palung National Park, Indonesia. We found when orangutans leave available fruit, it often is for nonfruit foods. We found evidence of orangutans navigating for nonfruit foods. GPS data show that orangutans leave or pass by fruit to consume other foods. When orangutans consumed nonfruit resources, 26% of the time, there was at least one available fruit resource within a 50-m radius. These data suggest that orangutans select nonfruit foods, strengthening the argument that feeding choice is consumer state-dependent, and leading us to argue for a revision of the use of "quality" as a descriptor of primate foods. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the influence of the period of occurrence of the European beaver (Castor fiber L.) population on foraging strategies and on the diversity of the species of cutting trees and shrubs. Two beaver populations at different stages of development - a younger (42yr) population from the Kampinos National Park and an older (72 yr) population from the Wigry National Park were studied. Both populations foraged according to the Optimal Foraging Theory (OFT), according to which the distance to available food depends on its size and the distance to reach it. The dominant factors modifying the foraging behavior of beavers and their foraging ranges were the presence of a dam, the availability of preferred species. The greater diversity in the areas where beaver are found may be the result of both beaver activity and the selection of more attractive areas for dam construction. [ABSTRACT FROM AUTHOR]

The variation in niche breadth can affect how species respond to environmental and resource changes. However, there is still no clear understanding of how seasonal variability in food resources impacts the variation of individual dietary diversity, thereby affecting the dynamics of a population's dietary niche breadth. Optimal foraging theory (OFT) and the niche variation hypothesis (NVH) predict that when food resources are limited, the population niche breadth will widen or narrow due to increased within-individual dietary diversity and individual specialization or reduced within-individual dietary diversity, respectively. Here, we used DNA metabarcoding to examine the composition and seasonality of diets of the avivorous bat Ia io. Furthermore, we investigated how the dietary niches changed among seasons and how the population niche breadth changed when the availability of insect resources was reduced in autumn. We found that there was differentiation in dietary niches among seasons and a low degree of overlap, and the decrease of insect resource availability and the emergence of ecological opportunities of nocturnal migratory birds might drive dietary niche shifts toward birds in I. io. However, the population's dietary niche breadth did not broaden by increasing the within-individual dietary diversity or individual specialization, but rather became narrower by reducing dietary diversity via predation on bird resources that served as an ecological opportunity when insect resources were scarce in autumn. Our findings were consistent with the predictions of OFT, because birds as prey for bats provided extremely different resources from those of insects in size and nutritional value. Our work highlights the importance of size and quality of prey resources along with other factors (i.e., physiological, behavioral, and life-history traits) in dietary niche variation. [ABSTRACT FROM AUTHOR]

Exploratory behaviour is one of the best-investigated behavioural traits. However, little is known about the influence of personality on novel food preferences in the social context, i.e., whether knowledge and previous experience can influence individual preference or if the presence of conspecifics can alter their choice. In the present study, we examined in cinereous tit (Parus cinereus) whether individuals with different personality types in the social context will prefer their own previously chosen novel food or change their preference in the presence of conspecifics. Second, we studied how the presence and behaviour of conspecifics may mediate individual personality. We conducted a standardized personality assay (exploratory behaviour) to analyse the individual personality. Birds were trained and provided with three different types of novel human-derived materials in both asocial and social contexts (with a conspecific). We recorded the latency to feed, time spent at the feeder, and the number of visits by fast and slow explorers in the two contexts, i.e., asocial and social. After the analyses of experimental data, we found that fast-exploring cinereous tits preferred peanuts in an asocial context, while slow explorers consumed a greater amount of sunflower seeds. In the social context, individuals of both personality types preferred peanuts to sunflower seeds. Additionally, individuals took less latency to eat food, made more visits to the feeder, and spent more time at the feeder in the social context than in the asocial context. Our findings show that foraging success may be determined by personality and social context. However, personality traits may be subject to constraints arising from correlations with other behavioural traits, and it remains a major challenge to understand the functional significance of individual foraging strategies. [ABSTRACT FROM AUTHOR]

In order to explain how crimes are carried out, and why at a particular place and time and against a specific target, crime studies increasingly harness theory from behavioural ecology, in particular Optimal Foraging Theory (OFT). However, an overview of their main findings does not exist. Given the growing focus on OFT as a behavioural framework for structuring crime research, in this article we review the extant OFT-inspired empirical crime research. Systematic search in Google Scholar and Web of Science yielded 32 crime studies, which were grouped into four categories according to their research topic. Empirical results largely support predictions made by OFT. However, there remains much potential for future OFT applications to crime research, in particular regarding the theoretical foundation of OFT in criminology, and through the application of contemporary extensions to OFT using specific tools developed for the study of animal foraging decisions. [ABSTRACT FROM AUTHOR]

Individual animals should adjust diets according to food availability. We used DNA metabarcoding to construct individual-level dietary timeseries for elephants from two family groups in Kenya varying in habitat use, social position and reproductive status. We detected at least 367 dietary plant taxa, with up to 137 unique plant sequences in one fecal sample. Results matched well-established trends: elephants tended to eat more grass when it rained and other plants when dry. Nested within these switches from ‘grazing’ to ‘browsing’ strategies, dietary DNA revealed seasonal shifts in food richness, composition and overlap between individuals. Elephants of both families converged on relatively cohesive diets in dry seasons but varied in their maintenance of cohesion during wet seasons. Dietary cohesion throughout the timeseries of the subdominant ‘Artists’ family was stronger and more consistently positive compared to the dominant ‘Royals’ family. The greater degree of individuality within the dominant family's timeseries could reflect more divergent nutritional requirements associated with calf dependency and/or priority access to preferred habitats. Whereas theory predicts that individuals should specialize on different foods under resource scarcity, our data suggest family bonds may promote cohesion and foster the emergence of diverse feeding cultures reflecting links between social behaviour and nutrition.

Foraging and acquiring of food is a delicate balance between managing the costs (both energy and social) and individual preferences. Previous research on solitarily foraging free-ranging dogs showed that they prioritise the nutritionally highest valued food, but do not ignore other less valuable food either, displaying typical scavenger behaviour. We conducted a similar experiment on 136 groups of dogs with the same set-up to see the change in foraging strategies, if any, under the influence of social cost like intra-group competition. We found multiple differences between the strategies of dogs foraging alone versus in groups with competition playing an implicit role in the dogs’ decision making when foraging in groups. Dogs continually assessed and evaluated the available resources in a “patch,” transitioning from random foraging to systematic foraging with time and more information. Dogs in groups used an, “eat first, sample afterwards” strategy whereas individual dogs sampled thoroughly before eating. Additionally, dogs in groups were quicker and more likely to respond to the experimental set-up and eat from it. The dogs adjusted their behaviour in terms of effort and time allocated according to the quality of the “patch.” Foraging in groups also provided benefits of reduced individual vigilance. The various decisions and choices made lend support to the optimal foraging theory wherein the dogs harvested the nutritionally richest patch possible with the least risk and cost involved but were willing to compromise if that was not possible. This underscores the cognitive, quick decision-making abilities and adaptable behaviour of these dogs, which is likely to have influenced the process of dog domestication.

Within optimal foraging theory animals should maximize their net energy gain while minimizing energetic costs. Energetic expenditure in wild animals is therefore key to measure proxies of fitness. Accelerometers are an effective tool to study animal movement-based energetics, but retrieval of the device is usually required and often difficult. Accelerometers measure movement across three axes (x, y, and z) and can be calibrated to measures of oxygen consumption from captive animals, providing estimates of overall energy expenditure. Measuring energetic expenditures using a global positioning system (GPS) approach could provide an alternative method to study energetic ecology. This technique uses locomotor speeds across a range of slopes from successive GPS locations, which can be linked to the energy expenditure from captive individuals. We compared accelerometer and GPS methods of energetic expenditures in free-roaming brown bears (Ursus arctos) on the Kodiak Archipelago, Alaska, USA. We then applied the GPS method to examine how multiple factors influenced brown bear movement-based daily energetic expenditures (MDEE). We found that while the two energetic measurements differed (Wilcoxon signed rank test: V = 2116, p < 0.001), they were positively correlated (r = 0.82, p < 0.001). The GPS method on average provided 1.6 times greater energy estimates than the accelerometer method. Brown bears had lower MDEE during periods of high food abundance, supporting optimal foraging theory. Reproductive status and age did not influence MDEE, however movement rates had a positive linear relationship. Energetic ecology is important for understanding drivers of animal movements. Data from GPS collars can provide useful information on energetic expenditures, but should be validated for the specific taxa, ecosystem, and GPS sampling rate used. Additionally, while movement-based estimates of energy expenditure can elucidate the mechanisms driving habitat use decisions, they may not fully reflect an animal's overall energy demands. Brown bear movement-based energetic expenditure was influenced by food abundance and movement rates, which highlighted the importance of access to prime foraging sites to enhance energetic efficiency. [ABSTRACT FROM AUTHOR]

Size‐structured differences in resource use stabilize species coexistence in animal communities, but what behavioral mechanisms underpin these niche differences? Behavior is constrained by morphological and physiological traits that scale allometrically with body size, yet the degree to which behaviors exhibit allometric scaling remains unclear; empirical datasets often encompass broad variation in environmental context and phylogenetic history, which complicates the detection and interpretation of scaling relationships between size and behavior. We studied the movement and foraging behaviors of three sympatric, congeneric spiral‐horned antelope species (Tragelaphus spp.) that differ in body mass—bushbuck (26–40 kg), nyala (57–83 kg), and kudu (80–142 kg)—in an African savanna ecosystem where (i) food was patchily distributed due to ecosystem engineering by fungus‐farming termites and (ii) predation risk was low due to the extirpation of several large carnivores. Because foraging behavior is directly linked to traits that scale allometrically with size (e.g., metabolic rate, locomotion), we hypothesized that habitat use and diet selection would likewise exhibit nonlinear scaling relationships. All three antelope species selected habitat near termitaria, which are hotspots of abundant, high‐quality forage. Experimental removal of forage from termite mounds sharply reduced use of those mounds by bushbuck, confirming that habitat selection was resource driven. Strength of selection for termite mounds scaled negatively and nonlinearly with body mass, as did recursion (frequency with which individuals revisited locations), whereas home‐range area and mean step length scaled positively and nonlinearly with body mass. All species disproportionately ate mound‐associated plant taxa; nonetheless, forage selectivity and dietary composition, richness, and quality all differed among species, reflecting the partitioning of shared food resources. Dietary protein exhibited the theoretically predicted negative allometric relationship with body mass, whereas digestible‐energy content scaled positively. Our results demonstrate cryptic size‐based separation along spatial and dietary niche axes—despite superficial similarities among species—consistent with the idea that body‐size differentiation is driven by selection for divergent resource‐acquisition strategies, which in turn underpin coexistence. Foraging and space‐use behaviors were nonlinearly related to body mass, supporting the hypothesis that behavior scales allometrically with size. However, explaining the variable functional forms of these relationships is a challenge for future research. [ABSTRACT FROM AUTHOR]

Many populations of consumers consist of relatively specialized individuals that eat only a subset of the foods consumed by the population at large. Although the ecological significance of individual‐level diet variation is recognized, such variation is difficult to document, and its underlying mechanisms are poorly understood. Optimal foraging theory provides a useful framework for predicting how individuals might select different diets, positing that animals balance the "opportunity cost" of stopping to eat an available food item against the cost of searching for something more nutritious; diet composition should be contingent on the distribution of food, and individual foragers should be more selective when they have greater energy reserves to invest in searching for high‐quality foods. We tested these predicted mechanisms of individual niche differentiation by quantifying environmental (resource heterogeneity) and organismal (nutritional condition) determinants of diet in a widespread browsing antelope (bushbuck, Tragelaphus sylvaticus) in an African floodplain‐savanna ecosystem. We quantified individuals' realized dietary niches (taxonomic richness and composition) using DNA metabarcoding of fecal samples collected repeatedly from 15 GPS‐collared animals (range 6–14 samples per individual, median 12). Bushbuck diets were structured by spatial heterogeneity and constrained by individual condition. We observed significant individual‐level partitioning of food plants by bushbuck both within and between two adjacent habitat types (floodplain and woodland). Individuals with home ranges that were closer together and/or had similar vegetation structure (measured using LiDAR) ate more similar diets, supporting the prediction that heterogeneous resource distribution promotes individual differentiation. Individuals in good nutritional condition had significantly narrower diets (fewer plant taxa), searched their home ranges more intensively (intensity‐of‐use index), and had higher‐quality diets (percent digestible protein) than those in poor condition, supporting the prediction that animals with greater endogenous reserves have narrower realized niches because they can invest more time in searching for nutritious foods. Our results support predictions from optimal foraging theory about the energetic basis of individual‐level dietary variation and provide a potentially generalizable framework for understanding how individuals' realized niche width is governed by animal behavior and physiology in heterogeneous landscapes. [ABSTRACT FROM AUTHOR]

The associations between feeding activities and environmental variables inform animal feeding tactics that maximize energetic gains by minimizing energy costs while maximizing feeding success. Relevant studies in aquatic animals, particularly marine mammals, are scarce due to difficulties in the observation of feeding behaviors in aquatic environments. This data scarcity concurrently hinders ecosystem‐based fishery management in the context of small toothed‐cetacean conservation. In the present study, a passive acoustic monitoring station was deployed in an East Asian finless porpoise habitat in Laizhou Bay to investigate potential relationships between East Asian finless porpoises and their prey. The data revealed that porpoises were acoustically present nearly every day during the survey period. Porpoise detection rates differed between spring and autumn in concert with activities of fish choruses. During spring, fish choruses were present throughout the afternoon, and this was the time when porpoise vocalizations were the most frequently detected. During autumn, when fish choruses were absent, porpoise detection rates decreased, and diurnal patterns were not detected. The close association between fish choruses and finless porpoise activities implies an "eavesdropping" feeding strategy to maximize energetic gains, similar to other toothed cetaceans that are known to engage similar feeding strategies. Underwater noise pollution, particularly those masking fish choruses, could interrupt finless porpoises' feeding success. Fisheries competing soniferous fishes with finless porpoise could impact finless porpoise viability through ecosystem disruption, in addition to fishing gear entanglement. [ABSTRACT FROM AUTHOR]

With increasing levels of antimicrobial resistance impacting both human and animal health, novel means of treating resistant infections are urgently needed. Bacteriophages and predatory bacteria such as Bdellovibrio bacteriovorus have been proposed as suitable candidates for this role. Microbes also play a key environmental role as producers or recyclers of nutrients such as carbon and nitrogen, and predators have the capacity to be keystone species within microbial communities. To date, many studies have looked at the mechanisms of action of prokaryotic predators, their safety in in vivo models and their role and effectiveness under specific conditions. Mathematical models however allow researchers to investigate a wider range of scenarios, including aspects of predation that would be difficult, expensive, or time-consuming to investigate experimentally. We review here a history of modelling in prokaryote predation, from simple Lotka-Volterra models, through increasing levels of complexity, including multiple prey and predator species, and environmental and spatial factors. We consider how models have helped address questions around the mechanisms of action of predators and have allowed researchers to make predictions of the dynamics of predator-prey systems. We examine what models can tell us about qualitative and quantitative commonalities or differences between bacterial predators and bacteriophage or protists. We also highlight how models can address real-world situations such as the likely effectiveness of predators in removing prey species and their potential effects in shaping ecosystems. Finally, we look at research questions that are still to be addressed where models could be of benefit. [ABSTRACT FROM AUTHOR]

Traditional agroforestry landscapes play a critical role in conserving biodiversity and sustaining rural livelihoods through multiple products and services. However, an unprecedented rise in the unsustainable utilisation and management of provisioning ecosystem services from these landscapes contributes to forest biodiversity loss and impacts livelihood efforts. The objective was to evaluate the link between distance and socio-ecological determinants and the provisioning ecosystem services consumption behaviour. This study tested whether "rural people's preferences and extent of PESs harvesting decrease as the distance from the village to forest patches increase, regardless of the prevalent socio-ecological conditions'. Using a structured questionnaire survey, data were collected in 882 households in four villages of Thulamela Municipality, Limpopo Province in South Africa. The data were analysed using Chi-square, Fidelity level, Use-value, Friedman test, and Generalised linear model. Consistent with the hypothesis, the results showed that local people harvest most of the provisioning ecosystem services at an immediate (1st) level, followed by intermediate (2nd) and far distance (3rd) levels. This study further revealed the existence of 108 useful tree species in the study areas. This study also found that although socio-ecological determinants influence consumption behaviour, the influence of specific socio-ecological determinants was not consistent across the different regimes of distance from the forest resources. The fact that there is a preference to use and harvest provisioning ecosystem services from the distance regime closest to the household, shows a concerted effort to conserve and enhance the abundance of multipurpose tree species in homesteads and the immediate areas. [ABSTRACT FROM AUTHOR]

Abstract Background Human memory appears to prioritise locations of high-calorie foods, likely as an adaptation for foraging within fluctuating ancestral food environments. Importantly, this “high-calorie bias” in human spatial memory seems to yield consequences for individual eating behaviour in modern food-abundant settings. However, as studies have mainly been conducted in European (Dutch) populations to date, we investigated whether the existence of the cognitive bias can be reasonably generalised across countries that vary on culturally-relevant domains, such as that of the USA and Japan. Furthermore, we investigated whether sociodemographic factors moderate the expression of the high-calorie spatial memory bias in different populations. Methods In a cross-cultural online experiment, we measured the food location memory of diverse participants from the USA (N = 72; 44.4% Male; 54 ± 15.99 years) and Japan (N = 74; 56.8% Male; 50.85 ± 17.32 years), using a validated computer-based spatial memory task with standardised images of high-calorie and low-calorie foods. To directly compare the magnitude of the high-calorie spatial memory bias in a broader cultural scope, we also included data from a previous online experiment that identically tested the food spatial memory of a Dutch sample (N = 405; 56.7% Male; 47.57 ± 17.48 years). Results In the US sample, individuals more accurately recalled (i.e. had lower pointing errors for) locations of high-calorie foods versus that of low-calorie alternatives (Mean difference = -99.23 pixels, 95% CI = [-197.19, -1.28]) – regardless of one’s hedonic preferences, familiarity with foods, and encoding times. Likewise, individuals in the Japanese sample displayed an enhanced memory for locations of high-calorie (savoury-tasting) foods (Mean difference = -40.41 pixels, 95% CI = [-76.14, -4.68]), while controlling for the same set of potential confounders. The magnitude of the high-calorie bias in spatial memory was similar across populations (i.e. the USA, Japan, and the Netherlands), as well as across diverse sociodemographic groups within a population. Conclusions Our results demonstrate that the high-calorie bias in spatial memory transcends sociocultural boundaries. Since the cognitive bias may negatively impact on our dietary decisions, it would be wise to invest in strategies that intervene on our seemingly universal ability to efficiently locate calorie-rich foods.

Pallid Swifts (Apus pallidus), as other swifts, are birds extremely adapted to an aerial lifestyle, showing unique adaptations that allow them to fly almost continuously. The diet of these non-stopping high-altitudinal aerial birds has been mostly studied through techniques that fail to produce highly resolved prey identifications, and for that have been replaced by molecular techniques, such as DNA metabarcoding. Faecal samples of Pallid Swifts were monthly collected from a colony in the north of Portugal during the breeding season. DNA from the faecal samples was used to sex the birds and to identify the arthropods present in the diet through DNA metabarcoding. From the detected prey items, 74 families were identified belonging to 16 orders, with Hymenoptera and Hemiptera being the most frequently consumed. There were seasonal variations in diet richness, composition and prey size. Regarding the diet of males and females, although no differences were found between the diet of males and females in terms of composition and richness, there were differences in the size of arthropods preyed by the different sexes, with males feeding on larger arthropods. The large seasonal variation in Pallid Swifts' diet during the breeding season is probably a result of spatiotemporal variation in aerial prey, of which swifts likely predate opportunistically. Although no significant differences were detected in diet richness and composition between sexes, the fact that males consumed larger prey may suggest the existence of sexual dietary segregation in this group of birds. At last, several pest species were found in these swifts’ diet, which, if studied through DNA metabarcoding, can be used to monitor small arthropods, including airborne pests.

A theoretical and applied literature has suggested that foragers search using Lévy flights, since Lévy flights can maximize the efficiency of search in the absence of information on the location of randomly distributed prey. Foragers, however, often have available to them at least some information about the distribution of prey, gained either through evolved mechanisms, experience and memory, or social transmission of information. As such, we might expect selection for heuristics that make use of such information to further improve the efficiency of random search. Here we present a general model of random search behavior that includes as special cases: area-restricted search, correlated random walks, Brownian search, and Lévy flights. This generative model allows foragers to adjust search parameters based on encounter-conditional and other heuristics. Using a simulation model, we demonstrate the efficiency gains of these search heuristics, and illustrate the resulting differences in the distributions of step-size and heading angle change they imply, relative to Lévy flights. We conclude by presenting a statistical model that can be fit to empirical data and a set of testable, quantitative predictions that contrast our model of adaptive search with the Lévy flight foraging hypothesis.

Active search for prey is energetically costly, so understanding how foragers optimize search has been central to foraging theory. Some theoretical work has suggested that foragers of randomly distributed prey should search using Lévy flights, while work on area-restricted and intermittent search strategies has demonstrated that foragers can use the information provided by prey encounters to more effectively adapt search direction and velocity. Previous empirical comparisons of these search modes have tended to rely on distribution-level analyses, due to the difficulty of collecting event-level data on encounters linked to the GPS tracks of foragers. Here we use a preliminary event-level data-set (18.7 hours of encounter-annotated focal follows over 6 trips) to show that two Colombian blowgun hunters use adaptive encounter-conditional heuristics, not non-conditional Lévy flights, when searching for prey. Using a theoretically derived Bayesian model, we estimate changes in turning-angle and search velocity as a function of encounters with prey at lagged time-steps, and find that: 1) hunters increase average turning-angle in response to encounters, producing a more tortuous search of patches of higher prey density, but adopt more efficient uni-directional, inter-patch movement after failing to encounter prey over a sufficient period of time; and, 2) hunters reduce search velocity in response to encounters, causing them to spend more of their search time in patches with demonstrably higher prey density. These results illustrate the importance of using event-level data to contrast encounter-conditional, area-restricted search and Lévy flights in explaining the search behavior of humans and other organisms.

With increasing levels of antimicrobial resistance impacting both human and animal health, novel means of treating resistant infections are urgently needed. Bacteriophages and predatory bacteria such as Bdellovibrio bacteriovorus have been proposed as suitable candidates for this role. Microbes also play a key environmental role as producers or recyclers of nutrients such as carbon and nitrogen, and predators have the capacity to be keystone species within microbial communities. To date, many studies have looked at the mechanisms of action of prokaryotic predators, their safety in in vivo models and their role and effectiveness under specific conditions. Mathematical models however allow researchers to investigate a wider range of scenarios, including aspects of predation that would be difficult, expensive, or time-consuming to investigate experimentally. We review here a history of modelling in prokaryote predation, from simple Lotka-Volterra models, through increasing levels of complexity, including multiple prey and predator species, and environmental and spatial factors. We consider how models have helped address questions around the mechanisms of action of predators and have allowed researchers to make predictions of the dynamics of predator–prey systems. We examine what models can tell us about qualitative and quantitative commonalities or differences between bacterial predators and bacteriophage or protists. We also highlight how models can address real-world situations such as the likely effectiveness of predators in removing prey species and their potential effects in shaping ecosystems. Finally, we look at research questions that are still to be addressed where models could be of benefit.

Granivory by ants affects plant populations negatively, although the interaction may become beneficial if ants disperse some seeds. Ants prefer seeds depending on their availability, weight, and dispersal structures. Nevertheless, the factors determining the fraction of seeds that are dispersed rather than eaten have not been analyzed. It may be expected that the most preferred seeds are the least dispersed, so dispersal would depend on the same seed traits driving predation. We assess whether seed weight, wind-dispersal structures, plant species abundance, and seasonal seed availability determine the preferences for different seed species in two species of ants in the genus Pheidole in Mexico. We also examine whether seed dispersal by Pheidole was affected by seed preferences, seed weight, plant species abundance, and seasonal availability. We conducted a cafeteria experiment with 11 seed species in 2 months with contrasting seed availability, and measured preferences based on the removal rates of different seed species. To determine the fraction of seed dispersed, some seeds were painted with fluorescent ink and tracked with UV light. Ants preferred seeds without dispersal structures, perhaps because they hamper seed transport, increasing the foraging costs. No other variables affected preferences. 11% of the removed seeds were dispersed. The probability that a seed was dispersed decreased with its preference. Dispersal probability was larger for common species and in the season when seeds are abundant These results suggest that ants tend to disperse seeds when they have good chances to find their preferred resources easily or closer to their nest. [ABSTRACT FROM AUTHOR]

Salmon (Oncorhynchus spp.) are an important food source for Grizzly Bear (Ursus arctos), but many salmon populations are declining. While most research on Grizzly Bear-salmon interactions occurs in coastal ecosystems, declining salmon may also affect Grizzly Bears in inland ecosystems where salmon are also an important part of their diet. We document changes in the number and distribution of observations of Grizzly Bears and changing Kokanee (i.e., landlocked Sockeye Salmon, Oncorhynchus nerka) abundance at an inland river. We hypothesized that reduced abundance of Kokanee would limit the number of Grizzly Bear observations at the river. We compared Kokanee abundance and Grizzly Bear observations (n = 535) between 2012 and 2019 at the Lardeau River, British Columbia, Canada. We used a generalized linear mixed model to test if the number of bear observations changed as a function of Kokanee abundance among four river reaches during eight consecutive years of study. Kokanee abundance was a strong statistical predictor of Grizzly Bear observations (ß = 0.52, P = 0.001, CI = 0.12-0.87), and Kokanee abundance and reach explained 73% of the variance. Our results suggest that reduced Kokanee abundance also reduces Grizzly Bear presence, likely because bears seek out other, more available food sources, away from Kokanee spawning habitat. This pattern could limit ecosystem services provided by Grizzly Bears adjacent to spawning areas and it could have implications for bear management and conservation. [ABSTRACT FROM AUTHOR]

Optimal foraging theory (OFT) and the energy maximization hypothesis (EMH) have long been essential when examining wildlife habitat selection. At high latitudes and altitudes, animals in winter face greater limitations in availability and accessibility of forage. Here we explore the foraging behavior of wood bison ( Bison bison athabascae ) during winter within the Ronald Lake bison herd in northeastern Alberta, Canada, and examine the trade-offs they face due to limitations in forage abundance and availability (snow conditions), as well as the need to minimize predation risk. We used Global Positioning System (GPS) location data collected from 70 female wood bison to identify winter foraging sites and craters selected by bison to access forage beneath the snow. Within wetlands used by bison we selected 190 pairs of used (foraged) and random (available) sites to test eight a priori hypotheses explaining how bison traded-off between forage availability, accessibility, and minimizing predation risk. We found with matched-paired logistic regression that Carex atherodes was 1.21-times more likely to be selected per unit increase in ground cover, compared to 1.17-times per unit ground cover for C. aquatilis and C. utriculata . However, all Carex species showed an increase in selection when cover was > 50% cover within individual craters. While the importance of Carex was clear, forage site selection was still inversely related to snow depth. There is also a neutralizing combined effect of snow depth and Carex species ground cover which suggests that bison maximized their energy return by avoiding areas with deep snow (> 30 cm) that demanded intensive cratering, even when highly selected forage was accessible beneath. Avoidance of forage areas with deep snow demonstrates that wood bison employed a foraging strategy that considers both forage availability and environmental conditions, with snow depth being a limiting factor. We highlight the relationship between optimal foraging based on food availability and the trade-offs within an energy restrictive winter season, furthering the understanding of how large herbivores forage strategically to maximize energy intake in northern environments., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

At cold winter temperatures, juvenile salmonids typically spend much of their time sheltering from predators, which negatively impacts foraging for food. Previous work shows that inter-individual variation in mitochondrial efficiency explains variation in food intake, growth and metabolic rate. Here, we examine whether inter-individual variation in mitochondrial efficiency predicts sheltering as a proxy of foraging patterns for overwintering juvenile Atlantic salmon ( Salmo salar ). PIT-tagged salmon were housed individually under winter conditions, and their use of a custom-built shelter was recorded automatically. In line with the previous research and estimates of relative predation risk, fish showed a broad preference for sheltering during the day and emerging to feed at night. However, they exhibited marked among-individual variation in their use of shelter, which was unrelated to body size but was predicted by mitochondrial function: there was a positive relationship between muscle mitochondrial phosphorylation efficiency and proportion of time spent in the shelter during the night but not during the day. Individuals with the most efficient mitochondria at producing ATP were thus able to spend more time sheltering from predators. This suggests that individual heterogeneity in cellular function may drive variation in the trade-off between foraging and sheltering, which has implications for selection pressures acting on wild populations.

Prevailing theories about animal foraging behaviours and the food webs they occupy offer divergent predictions about whether seasonally limited food availability promotes dietary diversification or specialization. Emphasis on how animals compete for food predominates in work on the foraging ecology of large mammalian herbivores, whereas emphasis on how the diversity of available foods generally constrains dietary opportunity predominates work on entire food webs. Reconciling predictions about what promotes dietary diversification is challenging because species' different body sizes and mobilities modulate how they seek and compete for resources-the mechanistic bases of common predictions may not pertain to all species equally. We evaluated predictions about five large-herbivore species that differ in body size and mobility in Yellowstone National Park using GPS tracking and dietary DNA. The data illuminated remarkably strong and significant correlations between body size and five key indicators of diet seasonality ( R 2 = 0.71-0.80). Compared to smaller species, bison and elk showed muted diet seasonality and maintained access to more unique foods when winter conditions constrained food availability. Evidence from GPS collars revealed size-based differences in species' seasonal movements and habitat-use patterns, suggesting that better accounting for the allometry of foraging behaviours may help reconcile disparate ideas about the ecological drivers of seasonal diet switching., Competing Interests: We declare we have no competing interests., (© 2024 The Author(s).)