Foraging Behavior Research Articles

Elucidating dietary secrets of the Blue‐headed Macaw, Primolius couloni (Sclater, 1876), through citizen‐sourced photographs

AbstractDietary data are vital for understanding species' resource requirements and ecological roles and supporting conservation efforts. The Blue‐headed Macaw, Primolius couloni, is a vulnerable and endemic species in the Amazon. Due to their rarity, elusive nature, complex forest canopy habitat, and occurrence in remote areas, we minimally know their dietary habits. To address this gap, we analysed photographs of Blue‐headed Macaws posted on wildlife‐focused social media platforms, specifically targeting images that capture foraging behaviour on plants. Photographs depicting the same foraging were included only once, and those where the plants were not identified were discarded. By doing so, we identified 36 distinct foraging events (or photos), primarily taken between July and October, concentrated in specific locations in Peru and Brazil, a potential seasonality in foraging. We documented 27 food plant species and items such as nectar (n = 9 photos), pulp (8), seeds (7), buds, bark (5 each), aril, and leaves (n = 1 photo each). Notably, floral resources, including nectar, are a potentially important food in the driest months. Using Levin's Index (Ba), we identified a broad dietary niche, indicating a generalist feeding strategy with a wide variety of plant species (Ba = 0.69) and food items (Ba = 0.88). Additionally, the study revealed interactions such as florivory, seed predation, bark consumption, and potential mutualistic roles like pollination and seed dispersal. Our photo‐centric approach here expanded the known dietary spectrum of the Blue‐headed Macaw from four to 31 plant species, offering new insights for conservation strategies. We recommend the preservation of identified food plants and suggest using these data to inform habitat restoration efforts that support the macaws' dietary needs and ecological functions. Future research should focus on continuous monitoring of these food plants to deepen our understanding of seasonal foraging trends and ecological interactions and refine conservation approaches.

Models of bee responses to land use and land cover changes in agricultural landscapes - a review and research agenda.

Predictive modelling tools can be used to support the design of agricultural landscapes to promote pollinator biodiversity and pollination services. Despite the proliferation of such modelling tools in recent decades, there remains a gap in synthesising their main characteristics and representation capacities. Here, we reviewed 42 studies that developed non-correlative models to explore the impact of land use and land cover changes on bee populations, and synthesised information about the modelled systems, modelling approaches, and key model characteristics like spatiotemporal extent and resolution. Various modelling approaches are employed to predict the biodiversity of bees and the pollination services they provide, with a prevalence of models focusing on wild populations compared to managed ones. Of these models, landscape indicators and distance decay models are relatively simple, with few parameters. They allow mapping bee visitation probabilities using basic land cover data and considering bee foraging ranges. Conversely, mechanistic or agent-based models delineate, with varying degrees of complexity, a multitude of processes that characterise, among others, the foraging behaviour and population dynamics of bees. The reviewed models collectively encompass 38 ecological, agronomic, and economic processes, producing various outputs including bee abundance, habitat visitation rate, and crop yield. To advance the development of predictive modelling tools aimed at fostering pollinator biodiversity and pollination services in agricultural landscapes, we highlight future avenues for increasing biophysical realism in models predicting the impact of land use and land cover changes on bees. Additionally, we address the challenges associated with balancing model complexity and practical usability.

Feeding efficiency of two coexisting nectarivorous bat species (Phyllostomidae: Glossophaginae) at flowers of two key-resource plants.

Animals should maximize their energy uptake while reducing the costs for foraging. For flower-visitors these costs and benefits are rather straight forward as the energy uptake equals the caloric content of the consumed nectar while the costs equal the handling time at the flower. Due to their energetically demanding lifestyle, flower-visiting bats face particularly harsh energetic conditions and thus need to optimize their foraging behavior at the flowers of the different plant species they encounter within their habitat. In flight cage experiments we examined the nectar-drinking behavior (i.e. hovering duration, nectar uptake, and the resulting feeding efficiency) of the specialized nectar-feeding bat Hylonycteris underwoodi and the more generalistic Glossophaga commissarisi at flowers of two plant species that constitute important nectar resources in the Caribbean lowland rainforests of Costa Rica and compared nectar-drinking behavior between both bat species and at both plant species. We hypothesized that the 1) specialized bat should outperform the more generalistic species and that 2) bats should generally perform better at flowers of the nectar-rich flowers of the bromeliad Werauhia gladioliflora than at the relatively nectar-poor flowers of the Solanaceae Merinthopodium neuranthum that has an extremely long flowering phase and therefore is an extremely reliable nectar resource, particularly for the specialized Hylonycteris. While we did not find substantial differences in the feeding efficiency of the generalist G. commissarisi, we observed an increased feeding efficiency of the specialized H. underwoodi at flowers of the nectar-poor M. neuranthum. This suggests that familiarity and ecological importance are more important determinants of the interaction than just morphological traits. Our results demonstrate that in addition to morphology, behavioral adaptations are also important drivers that determine the fitness of nectar-feeding bats. Both familiarity with and the ecological importance of a resource seem to contribute to shaping the interactions between pollinating bats and their plants.

Exposure to an insecticide formulation alters chemosensory orientation, but not floral scent detection, in buff-tailed bumblebees (Bombus terrestris)

Although pesticide-free techniques have been developed in agriculture, pesticides are still routinely used against weeds, pests, and pathogens worldwide. These agrochemicals pollute the environment and can negatively impact human health, biodiversity and ecosystem services. Acetamiprid, an approved neonicotinoid pesticide in the EU, may exert sub-lethal effects on pollinators and other organisms. However, our knowledge on the scope and severity of such effects is still incomplete. Our experiments focused on the effects of the insecticide formulation Mospilan (active ingredient: 20% acetamiprid) on the peripheral olfactory detection of a synthetic floral blend and foraging behaviour of buff-tailed bumblebee (Bombus terrestris) workers. We found that the applied treatment did not affect the antennal detection of the floral blend; however, it induced alterations in their foraging behaviour. Pesticide-treated individuals started foraging later, and the probability of finding the floral blend was lower than that of the control bumblebees. However, exposed bumblebees found the scent source faster than the controls. These results suggest that acetamiprid-containing Mospilan may disrupt the activity and orientation of foraging bumblebees. We hypothesize that the observed effects of pesticide exposure on foraging behaviour could be mediated through neurophysiological and endocrine mechanisms. We propose that future investigations should clarify whether such sub-lethal effects can affect pollinators’ population dynamics and their ecosystem services.

Applying the marginal value theorem when risk affects foraging behavior

Applying the marginal value theorem when risk affects foraging behavior

Lack of impact of Wolbachia on foraging behavior and morphological characteristics of the parasitoid wasp, Habrobracon hebetor (Braconidae)

Wolbachia are the most widespread intracellular alphaproteobacteria in insects with a variety of phenoptypic effects on the fitness and reproduction of their host, but much less is known about how these bacteria affect host behavior. In this study, we asked whether Wolbachia affects the foraging behavior of the parasitoid wasp Habrobracon hebetor (Hym.: Braconidae), an important biological control agent of many lepidopteran larvae. To test this, we analyzed the functional and numerical responses of Wolbachia-infected and uninfected (tetracycline cured) wasps, as well as morphological parameters. Functional response analysis showed Holling type II responses in both the Wolbachia-infected and uninfected females. The handling time and searching efficiency of Wolbachia-infected and uninfected females were similar, although the estimated maximum parasitism rate was shorter in infected females. Regardless of Wolbachia infection status, there was a negative non-linear relationship between the number of larvae parasitized by a female and an increase in the host density, reflecting a decrease in the total number of eggs laid. Our results also showed that Wolbachia had no effect on morphological traits of the parasitoid wasp. Together, these results suggest that Wolbachia which are prevalent in H. hebetor have limited impact on foraging behavior and morphology.

Multiple effects of weather on common waxbill group foraging and social behavior

Abstract The weather poses challenges for wildlife. Environmental challenges can be responded to at the group level by social animals, but the influence of weather on group behavior is poorly understood. We investigated how weather affects behavior in a gregarious species by monitoring common waxbills (Estrilda astrild) in a large mesocosm during 5 yr. We found seasonal patterns in collective foraging, aggressiveness, and the structure of the social network, usually showing 2 cycles per year: one peaking in Spring and a smaller one peaking in late Summer. Controlling for seasonality, we found behavioral changes related to increased energy demands in colder and/or cloudier days, such as more frequent and larger foraging groups that resulted in less-structured social networks. Rain and wind disturb movement, and we found that, on rainy days, foraging group journeys became briefer and more synchronous, resulting in stronger associations between individuals and less-structured networks, and that on windy days foraging groups were less frequent, larger, and with more within-group aggression. The results show that the weather has more varied effects than anticipated on ecologically relevant group behavior. We discuss how such weather-related effects can improve predictions of how social animals will react to environmental changes.

Pollen products collected from honey bee hives experiencing minor stress have altered fungal communities and reduced antimicrobial properties.

Fungi are increasingly recognised to play diverse roles within honey bee hives, acting as pathogens, mutualists, and commensals. Pollen products, essential for hive nutrition, host significant fungal communities with potential protective and nutritional benefits. In this study, we profile the fungal communities and antifungal properties of three pollen products from healthy and stressed hives: fresh pollen collected by forager bees from local plants; stored pollen packed into the comb inside the hive; and bee bread, which is stored pollen following anaerobic fermentation used for bee and larval nutrition. Using amplicon sequencing, we found significant differences in fungal community composition, with hive health and sample type accounting for 8.8% and 19.3% of variation in beta diversity, respectively. Pollen and bee bread extracts had species-specific antimicrobial activity and inhibited the fungal hive pathogens Ascosphaera apis, Aspergillus flavus, and Aspergillus fumigatus, and the bacterial hive pathogen Paenibacillus larvae. Activity was positively correlated with phenolic and antioxidant content and was diminished in stressed hives. The plant source of pollen determined by amplicon sequencing differed in stressed hives, suggesting altered foraging behaviour. These findings illustrate the complex interplay between honey bees, fungal communities, and hive products, which should be considered in hive management and conservation.

The Impact of Food Enrichment on the Behavior of Cownose Ray (Rhinoptera bonasus) Kept under Human Care

The cownose ray (Rhinoptera bonasus) faces vulnerability primarily due to unregulated fishing, resource overexploitation, and habitat degradation. Consequently, individuals maintained under human care play a pivotal role in species conservation, particularly when their welfare is prioritized. Achieving optimal welfare in aquarium settings relies heavily on effective management practices, notably environmental enrichment. However, research on the efficacy of such techniques for cownose rays remains limited. Thus, this study sought to evaluate the impact of various food enrichment items on the behavior of four individuals at the São Paulo Aquarium in Brazil. The project encompassed three phases: baseline, enrichment, and post-enrichment. Enrichment items, designed to mimic the species’ natural foraging behavior, included an ice block containing food, food hidden in vegetables fixed to structures at the bottom of the tank, a tray with substrate and food, and a perforated plastic container with food inside. Behavioral observations utilized focal sampling with instantaneous recording every minute. Results showed increased foraging activity in the post-enrichment phase, whereas swimming increased and following behaviors decreased during the enrichment phase. Additionally, foraging behaviors predominantly occurred near the aquarium bottom. Overall, findings suggest that enrichment items effectively stimulated natural behaviors in cownose rays and were very attractive to the fish, advocating for their integration into species management protocols to enhance welfare.

The invasive bumblebee Bombus terrestris (Linnaeus, 1758) disrupts the adaptive function of heteranthery by indiscriminately visiting the pollinating and feeding anthers of Senna arnottiana flowers.

Heteranthery, the presence of different types of anthers on the same flower, is a floral adaptation that aims to balance the need for pollinators to collect pollen as a food resource while ensuring sufficient pollen for pollination. We investigate the role of heteranthery in the pollination of Senna arnottiana flowers and how it is affected by the behaviour of visiting bee species, with a particular focus on the impact of the invasive bumblebee Bombus terrestris. In three populations of S. arnottiana we measured the size of three sets of anthers and style, stigma-anther separation, pollen quantity and fruit set, and contrasted it with the body size, behaviour, and pollination effectiveness of all floral visitors. Different bee species visited S. arnottiana flowers, and their foraging behaviour varied. Large-bodied native bees, including Centris cineraria, Caupolicana sp. and Cadeguala occidentalis, preferentially visited short anthers, whereas B. terrestris, an exotic bumblebee, foraged from both short and long anthers without distinction. In addition, B.terrestris contacted the stigma at a lower rate than large-bodied native bees. Instead of concentrating its pollen-gathering efforts on the feeding anthers, as predicted by the "division of labor" hypothesis, B. terrestris indiscriminately visited both types of anthers similarly. This behaviour of B. terrestris may disrupt the adaptive significance of heteranthery by mixing the roles of pollination and feeding anthers of S. arnottiana. Therefore, our results highlight the potential disruption of this relationship by exotic pollinators and the need to consider it in conservation efforts.

Cadmium soil contamination alters plant-pollinator interactions

Soil heavy metal contamination is often an unintended byproduct of historic land-use. This contamination can negatively impact resident plants and their interactions with other organisms. Plant fitness in contaminated landscapes depends not only on plant growth, but also on the maintenance of interactions with pollinators. Cadmium (Cd) is a heavy metal that is commonly found in agricultural, urban, and industrial ecosystems as a legacy of historic land-use. It is a prioritized pollutant in soils because of its wide distribution and strong biotoxicity. To understand how Cd influences plant growth and pollinator interactions, we grew sunflowers in media with three different Cd concentrations to represent the range of Cd contamination faced by sunflowers growing on land recovering from past land-use. We measured Cd contamination effects on sunflower morphology and pollinator foraging behavior, specifically the number of visits and visit duration. We then measured seed number and weight to determine if contamination directly or indirectly, as mediated by pollinators, altered plant fitness. Plant height was negatively correlated with Cd concentration, but contamination alone (in the absence of pollinators) did not affect sunflower reproduction. Bumble bees visited sunflowers grown in Exceeding Threshold Cd concentrations less often and for shorter time compared to visits to Below Threshold Cd sunflowers, but honey bees and sweat bees showed similar foraging behavior across Cd contamination treatment levels. Sunflower seed set was positively correlated with the total number of pollinator visits, and sunflowers grown in Exceeding Threshold Cd soil had marginally lower seed set compared to those grown in Below Threshold Cd soil. Our results suggest that at Exceeding Threshold Cd contamination levels plant-pollinator interactions are negatively affected with consequences for plant fitness.

Assessing the Home Range, Foraging Pattern and Roost Fidelity of Greater Short-nosed Fruit Bat (Cynopterus sphinx) in a Semi-Urban Environment

Radio telemetry is a method used in wildlife ecology to examine the movements and behaviours of animals, as well as to define their home ranges and habitat preferences. Bats, a highly diverse group of mammals, are recognized for their essential contributions to ecosystems, including seed dispersal, pollination, and pest control through their foraging activities. This study utilised radio telemetry to explore the basic foraging behaviours, range of movement, and roosting flexibility of the Cynopterus sphinx species. A total of 15 bats were equipped with compact, hand-wired, two-stage transmitter radio devices, including two harem males, nine harem females, and four non-harem males. Three groups used TRX-1000S receivers and collapsible 5-element Yagi antennas to track these radio-tagged bats. Our findings indicate that the radio-tagged female bats were the first to leave their roosts, with emergence times between 18:15 and 19:18 hrs. In contrast, harem males emerged last, following the quicker departure of non-harem males. The harem males covered an average foraging distance of 2.4 km (±0.3 km), whereas non-harem males travelled further. Both male and female bats visited multiple feeding sites nightly, with females travelling an average distance of 4.5 km (±0.9 km). Time spent at foraging sites varied among individuals. Males show higher roost fidelity than females, who frequently move between harems and roost sites. The study highlighted gender-specific differences in emergence times and distinct foraging behaviours, underlining the importance of understanding these patterns for conservation and habitat management efforts, which are crucial for supporting bats' roles as providers of ecosystem services.

To move or not to move: Dispersal of Orius insidiosus in strawberry plants

AbstractSpatial and temporal distribution of food resources influences predatory insects' foraging and dispersal behavior. Orius insidiosus (Say) (Hemiptera: Anthocoridae) is a good biological control agent of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), in the strawberry crop and consumes two‐spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), and pollen as well. Augmentative biological control programs may fail if, following release, predators disperse from the crop. We studied the dispersal of O. insidiosus as a function of pollen availability, density of their main prey WFT, and the presence of the alternative prey TSSM, within and between strawberry plants. We found that O. insidiosus remained on the flowers during the 24 h of the assay. The dispersal of predators to a neighboring flower with thrips was approximately six times greater from a flower without pollen than from a flower with pollen. When TSSM was the only prey available, O. insidiosus colonized the leaves, and its dispersal within the plant was greater. At the plot scale, the predator dispersal from the release plant to other plants also depended on the presence of flowering plants and prey. Our results highlight the importance of flowering plants and pollen availability in enhancing the persistence of O. insidiosus in strawberry plants. Releases of this predator in the strawberry crop should be after the beginning of flowering, even at low WFT densities.

Cognitive abilities related to foraging behavior in Vespula vulgaris (Hymenoptera: Vespidae)

Vespula vulgaris is an invasive social wasp that has become established in many parts of the world. Plastic cognitive systems are expected to be advantageous for invasive species, given that they continuously face dynamic and unpredictable environments. We analyzed foraging behavior associated with undepleted and depleted resources. The wasps were trained to associate a certain location with food and we recorded their behavior after successive displacement of it. We also studied how long wasps continued to search for food that was no longer available and whether it was dependent on experience. We found that when wasps associated a certain location with food, they returned to the same site even though food was no longer available or had been displaced. Handling time remained constant, while relocation time and learning flights decreased with experience. With a food position change, learning flights increased and searching time varied with experience. When food was removed, hovering and landings were greatest in wasps that had the most experience with the resource, although extinction of the searching response was not dependent on experience. Our results illustrate the plasticity of wasp behavior in uncertain foraging contexts, which could have allowed the species to establish successfully in new habitats.

Artificial light at night drives diel activity patterns of synanthropic pipistrelle bats and their prey

The use of artificial light at night (ALAN) has increased drastically worldwide over the last decades. ALAN can have major effects on nocturnal communities, including insects and bats. Insects are attracted to street lights and few bat species take advantage of this by foraging on the attracted insects. ALAN potentially affects the temporal patterns of insect abundance and thereby bat foraging behaviour. In a natural dark environment, these patterns are usually bimodal, with an activity peak in the early evening and the morning. Little is known about how ALAN affects insect presence throughout the night, and whether the light spectrum plays a role. This is important, as these temporal changes may be a key driver of disturbances in bat-insect interactions. Here, we studied how white and red light affect insects' and bats' nightly activity patterns. The activity of insects and bats (Pipistrellus spp.) was recorded throughout the night at seven experimentally illuminated sites in a forest-edge ecosystem. ALAN disrupted activity patterns, with both insects and bats being more active throughout the night. ALAN facilitated all-night foraging in bats especially near white light, but these effects were attenuated near red light. The ability to forage throughout the night may be a key advantage causing synanthropic bats to dominate in illuminated environments, but this could also prove detrimental in the long term. As red light reduced disturbing effects of ALAN on insects and bats diel activity pattern, it opens the possibility of using spectral composition as a mitigation measure.

Living together, feeding apart: the comparative foraging ecology of two African flycatcher species

This study examined how habitat and resource conditions influence the foraging behaviour and ecology of the Pale (Pallid) Flycatcher Agricola pallidus and Marico Flycatcher Bradornis mariquensis, two perch-and-pounce insectivores that swoop on prey from elevated perches. These species were studied in the early 1980s at the Nylsvley Nature Reserve in Limpopo Province, South Africa, where Marico Flycatchers occupied fine-leafed, spinescent Vachellia (Acacia) tortilis-dominated woodland, while Pale Flycatchers were confined to Burkea africana-dominated mesophyll woodland. These two woodland types correspond to two contrasting savanna types across Africa more broadly: arid-eutrophic, fine-leafed savannas and mesic/moist-dystrophic, broad-leafed woodlands. Their juxtaposition at the Nylsvley Reserve provided an opportunity to explore the factors affecting the habitat preferences and foraging behaviour of these two species. Acacia woodlands had higher invertebrate abundance, at least on the ground, and lower groundcover than Burkea woodlands in both seasons, although the difference was less during the dry season. Throughout the year, Marico Flycatchers consistently foraged at a faster rate, pouncing more frequently and more successfully on prey than did Pale Flycatchers. They also spent less time searching from each perch and gave up sooner if they found nothing. The average time difference between successful and unsuccessful searches was only a few seconds for both species, however. Presumably because they occupied a less productive woodland, Pale Flycatchers had considerably larger home ranges and occurred at lower densities overall, and so experienced fewer intraspecific and interspecific interactions. In contrast, Marico Flycatchers faced more competition both intra- and interspecifically, especially in the dry season when prey was scarce; they lost most of their conflicts, all with larger birds. Habitat separation between these two flycatcher species is apparently maintained by the differences in habitat structure, resource availability and occasional interspecific interactions, in which Marico Flycatchers dominated Pale Flycatchers.

Multi-omics unveils tryptophan metabolic pathway as a key pathway influencing residual feed intake in Duroc swine.

The genetic trait of residual feed intake (RFI) holds considerable importance in the swine industry. Recent research indicates that the gut microbiota of pigs plays a pivotal role in the manifestation of the RFI trait. Nevertheless, the metabolic pathways involved in the functioning of these microorganisms remain elusive. Thus, based on the ranking of the RFI trait in Duroc pigs, the present study selected the top 10 and bottom 10 pigs as the experimental subjects. The distribution and metabolite differences of cecal microbiota were analyzed using 16S rRNA gene sequencing and liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. The low RFI cecal group was named LRC, and the high RFI cecal group was named HRC. The results indicate that the LRC group had lower RFI, feed conversion ratio (FCR), average daily feed intake (ADFI) (p < 0.001), and thinner backfat (p < 0.05) compared with the HRC group. We simultaneously recorded the foraging behavior as well, the LRC group had a significant increase in total time spent at the feeder per day (TPD) (p < 0.05) and a significant increase in average feed intake per mins (AFI) and the number of visits to the feeder per day (NVD) compared to the HRC group (p < 0.001). Clostridium_XVIII, Bulleidia, and Intestinimonas were significantly enriched in the LRC group (p < 0.01), while Sutterella, Fusobacterium, and Bacteroides were significantly increased in the HRC group (p < 0.01). In the metabolome, we detected 390 (248 metabolites up and 142 down in the LRC compared with HRC), and 200 (97 metabolites up and 103 down in the LRC compared with HRC) differential metabolites in positive and negative ionization modes. The comprehensive analysis found that in the LRC group, Escherichia and Eubacterium in the gut may increase serotonin content, respectively. Bacteroides may deplete serotonin. We suggest that the RFI may be partly achieved through tryptophan metabolism in gut microbes. In individuals with low RFI, gut microbes may enhance feed efficiency by enhancing host synthesis and metabolism of tryptophan-related metabolites.

Optimal design of structural engineering components using artificial neural network-assisted crayfish algorithm

Abstract Optimization techniques play a pivotal role in enhancing the performance of engineering components across various real-world applications. Traditional optimization methods are often augmented with exploitation-boosting techniques due to their inherent limitations. Recently, nature-inspired algorithms, known as metaheuristics (MHs), have emerged as efficient tools for solving complex optimization problems. However, these algorithms face challenges such as imbalance between exploration and exploitation phases, slow convergence, and local optima. Modifications incorporating oppositional techniques, hybridization, chaotic maps, and levy flights have been introduced to address these issues. This article explores the application of the recently developed crayfish optimization algorithm (COA), assisted by artificial neural networks (ANN), for engineering design optimization. The COA, inspired by crayfish foraging and migration behaviors, incorporates temperature-dependent strategies to balance exploration and exploitation phases. Additionally, ANN augmentation enhances the algorithm’s performance and accuracy. The COA method optimizes various engineering components, including cantilever beams, hydrostatic thrust bearings, three-bar trusses, diaphragm springs, and vehicle suspension systems. Results demonstrate the effectiveness of the COA in achieving superior optimization solutions compared to other algorithms, emphasizing its potential for diverse engineering applications.

Notes on the terrestrial foraging repertoire of Indian pond heron Ardeola grayii (Sykes, 1832) feeding on the American cockroach, Periplaneta americana (Linnaeus 1758)

ABSTRACT This letter reports a novel observation of terrestrial foraging behavior by the Indian Pond Heron (Ardeola grayii), highlighting its adaptability and resourcefulness in exploiting diverse food sources. The study documents the heron’s unusual feeding habits in Kollam Beach, India, where it demonstrates a preference for terrestrial environments despite its aquatic habitat. Through detailed observations and video recordings, the authors shed light on the heron’s foraging behavior and its implications for our understanding of wading bird ecology.

A taste of space: Remote animal observations and discrete-choice models provide new insights into foraging and density dynamics for a large subarctic herbivore.

Competition for resources and space can drive forage selection of large herbivores from the bite through the landscape scale. Animal behaviour and foraging patterns are also influenced by abiotic and biotic factors. Fine-scale mechanisms of density-dependent foraging at the bite scale are likely consistent with density-dependent behavioural patterns observed at broader scales, but few studies have directly tested this assertion. Here, we tested if space use intensity, a proxy of spatiotemporal density, affects foraging mechanisms at fine spatial scales similarly to density-dependent effects observed at broader scales in caribou. We specifically assessed how behavioural choices are affected by space use intensity and environmental processes using behavioural state and forage selection data from caribou (Rangifer tarandus granti) observed from GPS video-camera collars using a multivariate discrete-choice modelling framework. We found that the probability of eating shrubs increased with increasing caribou space use intensity and cover of Salix spp. shrubs, whereas the probability of eating lichen decreased. Insects also affected fine-scale foraging behaviour by reducing the overall probability of eating. Strong eastward winds mitigated negative effects of insects and resulted in higher probabilities of eating lichen. At last, caribou exhibited foraging functional responses wherein their probability of selecting each food type increased as the availability (% cover) of that food increased. Space use intensity signals of fine-scale foraging were consistent with density-dependent responses observed at larger scales and with recent evidence suggesting declining reproductive rates in the same caribou population. Our results highlight potential risks of overgrazing on sensitive forage species such as lichen. Remote investigation of the functional responses of foraging behaviours provides exciting future applications where spatial models can identify high-quality habitats for conservation.