Biology subjects

Vander Wal, E.

Publications and source records attributed to Vander Wal, E..

At least 19 recordsLinked to original sources

bioRxiv2026

Social anchors: how previous social locations shape current animal movement and habitat selection

Memory of past space use is an important factor in habitat selection, but memory of what? The concept of memory captures the geographic spaces that an animal has used in the past. There are, however, competing reasons why animals occupy a given space. Species may occupy space due to particular aspects of their memory. Using integrated step selection analysis, we tested the relative importance of memory: previous use of high forage quality or where social interactions occurred at two temporal scales in caribou (Ranger tarandus). The most important parameter to explain intra-seasonal movement was geographic memory. At the inter-annual scale, caribou more strongly revisited locations with high quality forage and where they had formed dyads with conspecifics. We posit that remembered locations of social fusion can function as social anchors. The effects of memory on movement behaviour depend upon the context, both social and resource-based, and not geographic space alone.

ecology↗

bioRxiv2026

When blood is not thicker than water: Social information landscapes offset the food-fear trade-off in habitat selection decisions

1. Group foraging reduces the risks associated with foraging: larger groups dilute individual predation risk, allow group members to share the costs of vigilance, and provide a social structure for exchanging information about predators. The benefits of shared social information over simple safety in numbers should depend on the relationships among group members. Consequently, group composition should affect the selection of risky and safe habitats in social species. 2. We asked whether relationships among elk (Cervus canadensis) group members moving together influence their selection of risky habitats more than grouping alone. We tested three hypotheses. The familiarity hypothesis predicts that elk with close social ties are most likely to select risky habitats together. The inclusive fitness hypothesis predicts that the closest genetic relatives are most likely to select risky habitats together. The dilution hypothesis predicts that familiarity and genetic relationships do not influence habitat selection, with all group foraging benefits derived from proximity to others. 3. We used integrated Step Selection Analysis to test whether the identity of the closest group members influenced habitat selection. We tested whether the relationship of the nearest elk--either genetic or social--incentivized selection of risky habitat more than proximity to the nearest elk. 4. Group foraging clearly reduced risk, with elk more likely to select risky habitat when near others. Elk were also more likely to select risky habitats when near closer relatives, albeit with considerable variation among individuals. However, familiarity had a large and consistent effect: elk were far more likely to select risky habitats when near socially familiar group members. 5. Our results suggest that information shared within foraging groups, especially between socially familiar individuals, may lower the risks associated with habitat selection. Similarly, the benefits of reliable social information for reducing risk likely incentivizes the formation of stronger social ties within foraging groups. This positive feedback between social familiarity and habitat selection could thereby increase access to profitable habitats that are otherwise too risky, cementing what we term the social information landscape as a key driver of movement and habitat selection.

ecology↗

bioRxiv2026

Sociality shapes context-dependent stress responses to anthropogenic disturbance in African elephants

Social relationships can buffer individuals against environmental challenges, reducing the physiological costs of disturbance. Assessing how social and environmental conditions jointly shape physiological stress is critical for predicting individual responses to disturbance, particularly in managed populations. We evaluated whether social and environmental stressors act additively or whether social context modifies physiological responses to environmental challenges. We combined behavioural data and faecal glucocorticoid metabolite samples from a small, intensively monitored population of African elephants (Loxodonta africana) in a fenced reserve. Using a Bayesian framework, we tested how social factors interacted with variation in the biophysical environment, including natural environmental and anthropogenic disturbances, to predict glucocorticoid concentrations. Natural environmental variables, including weather, water availability, and season, did not predict glucocorticoid concentrations. In contrast, helicopter use, a common management intervention, was associated with higher glucocorticoid concentrations. Social effects were context dependent. Following disturbance, low-ranking individuals showed higher glucocorticoid concentrations than high-ranking individuals, whereas this pattern reversed under low-disturbance conditions. Individuals with more social connections had lower glucocorticoid concentrations, but this effect was evident only under non-disturbance conditions. Measures of betweenness centrality did not predict glucocorticoid levels. These results demonstrate that social factors mediate physiological responses to anthropogenic disturbance and that management actions can impose uneven physiological costs across individuals. Quantifying interactions between social factors and the biophysical environment may improve conservation and management strategies for social species. Integrating physiological responses to interactions between social factors and the biophysical environment can guide conservation strategies and improve management interventions in social species.

animal behavior and cognition↗

bioRxiv2026

Shifting forage selection subsidizes seasonal resource scarcity

O_LINitrogen (N) is limiting for terrestrial herbivores, particularly over winter. Caribou (Rangifer tarandus) have adapted to seasonal scarcity of N by accruing muscle mass during the growing season when N is more abundant. C_LIO_LINitrogen stored in muscle tissue is then relied upon during winter to compensate for dietary deficits. Once their diet shifts from N-rich vascular plants to N-poor lichen over winter, caribou can lose [~]30% of their muscle mass. As catabolized N is shed in urine on wintering grounds, caribou could act as elemental transport across seasons and landscapes. Furthermore, if deposited N is taken up by lichen or other winter forage, it might enrich the nitrogen-poor winter diet of caribou in the future. C_LIO_LIWe tested this potential transport via three steps. We analysed Cladonia spp. lichen and vascular plants upon which caribou forage across Fogo Island, Newfoundland, using %N content as our metric of forage quality. We then compared seasonal habitat selection responses to forage quality by caribou using integrated step selection analyses. In summer, caribou selected areas with higher vascular plant %N but did not select nor avoid Cladonia quality. In contrast, caribou selected sites with higher quality Cladonia in winter but responded neutrally to vascular plant quality. C_LIO_LIWe compared seasonal distributions of caribou to determine whether nitrogen consumed in summer and deposited in winter would occur in spatially discrete locations. Population-level kernel density estimates for summer and winter in this island herd were mostly non-overlapping, lending credence to the potential landscape effects of N transport. C_LIO_LIWhen viewed together with established seasonal changes in woodland caribou physiology, sociality, and forage preferences, the shifts in habitat selection and seasonal ranges we observe here could serve as an adaptive strategy for caribou to recycle N and mitigate winter nutrient scarcity. C_LI

ecology↗

bioRxiv2025

Not so scary after all? Decoding the landscape of fear through hormonal responses to risky times and places

Prey must balance the energetic benefits of foraging with avoiding predation risk. This risk-reward trade-off, a cornerstone of behavioural ecology, hinges not only on realized predation risk but also on how prey perceive that risk. We often assume energetically rewarding habitats must be inherently risky because prey often increase their vigilance in these habitats or avoid them altogether. However, our assumption that these antipredator behaviours reflect perceived risk frequently goes untested. We used non-behavioural data to test our assumptions about which habitats prey perceive as risky by pairing observations of habitat use of elk (Cervus canadensis) with their physiological responses measured from faecal hormones: glucocorticoids (GC), which reflect stress from perceived risk and hunger, and triiodothyronine (T3), which increases with energy intake. Elk had lower GC and T3 in the forest, a putatively safer and poorer foraging habitat than cropland, where they produced more T3, indicating foraging. Surprisingly, GC levels were consistent in cropland, even during the daytime when human activity--and putative risk--peaked. This lack of risk responsiveness highlights that physiological responses are a nuanced integration of perceived risk and reward rather than a guaranteed outcome of habitat use. Our study challenges the assumption that high-reward habitats are inherently risky, and that safer habitats limit energy intake, revealing that the assumptions we make about habitats from a behavioural lens may not always be the reality for prey.

ecology↗

bioRxiv2025

Remote inferences and direct observations provide complementary insights into foraging behavior

Behaviorists sometimes view askance studies where researchers indirectly observe animals, consequently challenging whether remotely inferred behavior is true behavioral research. Alternatively, others purport that technological advancements, like Global Position System (GPS) tags or biologgers, have expanded the scope of behavioral research to temporal and spatial scales infeasible for direct observation. To spotlight strengths and shortcomings in approaches to behavioral research, we interrogated the use of techniques and their assumptions in foraging research, a behavior of interest to ecologists and behaviorists. We reviewed 604 foraging behavior studies to synthesize and compare foraging research across disciplines, taxa, and methods. We sorted approaches by the data they collect and their associated assumptions and determined that rather than two categories of direct vs. remote, there were five: direct observation, tracking, biologger, remote audio-visual, and remote spatial. Categories differed in their spatial extents, with remote spatial research having a much larger extent (up to 1.6 million km2) than direct observational or remote audio-visual studies. Remote spatial studies also spanned large temporal extents, but temporal coverage (the proportion of total study duration when data are actively collected) was lower compared to biologger research. Methods were also applied to different stages of the behavioral process of foraging: direct observations and tracking involved searching for resources at finer scales. 23% of studies used > 2/5 categories. A compound approach provided a more nuanced and complete description of foraging behavior. Thus, our understanding of behavior improves when multiple approaches are applied in conjunction to our question of interest. Lay summaryHow do you study behavior? Your first response might be simply watching animals behave. While there are many ways to indirectly infer behavior without directly observing wildlife, some question these approaches because we cannot be 100% confident in the inferred behavior. We reviewed >600 behavior studies and found that though remote inferences rely on assumptions, so do direct observations. Remote inferences also permit studying temporal and spatial scales infeasible when watching wildlife directly.

animal behavior and cognition↗

bioRxiv2024

Social facilitation of risky habitats in woodland caribou: responses to fire and roads

Habitat change and subsequent trophic effects remain the dominant hypothesis for woodland caribou (Rangifer tarandus) population declines. Boreal forests are undergoing rapid changes, including expanding linear features and climate-induced increased wildfire activity. Within these landscapes caribou habitat selection and movement ought to maximize benefits while mitigating costs, e.g. predation risk, but spatial locations are likely not fixed in their cost-benefit ratio. For caribou, costs and benefits may vary seasonally and by social context. To test the effects of season and social context on caribou movement and selection of potentially risky habitats, we used a socially informed integrated step selection analysis (iSSA). We tested responses to two forms of risk in Terra Nova National Park, NL: roads and areas burned 2 - 75 years prior. Caribou avoided areas near roads irrespective of season. Burned area avoidance varied by season and burn age. Caribou avoided roads less and selected burns more in a social context. Social facilitation may permit the use of areas that were functionally unavailable to animals that were not in groups. As the most at-risk populations of woodland caribou exist at low density in highly disturbed landscapes, our results highlight the importance of considering sociality in maintaining access to resources.

ecology↗

bioRxiv2024

Evidence for optimal behavior of predators from parallel field investigations in two distinct wolf-prey systems

Animals behave optimally when they minimize their costs while maximizing their energetic gain. Optimal foraging theory predicts that with decreasing resource abundance, animals will increase 1) niche breadth, 2) territory size and movement distance, and 3) time spent at resource patches. We test these predictions by investigating clusters from GPS collared wolves (Canis lupus) in two predator populations with marked differences in their prey composition and abundance. As expected, wolves in a less abundant system increase niche breadth, territory size, step lengths, and time spent at each kill. Our work provides evidence of optimal behavior in an apex predator which can support population resilience across changing landscapes.

ecology↗

bioRxiv2024

Dead zones, obstructions, and missed captures: A novel approach for determining the Effective Capture Area for remote camera traps

1. Camera traps (CTs) have become cemented as an important tool of wildlife research, yet, their utility is now extending beyond academics, as CTs can contribute to more inclusive place-based wildlife management. From advances in analytics and technology, CT-based density estimates of wildlife is an emerging field of research. Most CT-based density methods require an estimate of the size of the viewshed monitored by each CT, a parameter that may be highly variable and difficult to quantify. 2. Here, we developed and tested a standardized field and analytical method allowing us to predict the probability of photographic capture as it varies within CT viewshed. We investigated how capture probability changes due to environmental influences, i.e., vegetation structure, ambient temperature, speed of subject, time of day, in addition to internal factors from CTs themselves, i.e., sensitivity settings, number of photos taken, and CT brand. We then summarize these spatial capture probability kernels into a Realised Viewshed Size (RVS)--the capture-probability corrected size of a CTs viewshed 3. We found that RVS values are heavily influenced by location-specific environmental factors, i.e., vegetation structure, technological delays associated with CTs themselves, i.e., refractory period, and internal CT settings, i.e., sensitivity, number of photographs taken. We also found that the RVS values computed using our methodology are substantially smaller than reported values in the literature. 4. Imprecision surrounding CT viewshed areas can create propagating bias when implementing CT-based density estimators. Our method can change how practitioners consider photographs for use in CT density estimators thus increasing the reliability of CT-based density estimation, and contribute to more accessible wildlife management practices.

ecology↗

bioRxiv2024

Movement-integrated habitat selection reveals wolves balance ease of travel with human avoidance in a risk-reward trade-off

Anthropogenic linear features are often linked to alterations in wildlife behaviour and movement. Landscape features such as habitat can have important mediating effects on wildlife response to disturbance and yet is rarely explicitly considered in how it interacts with other features. This study tests the effects of habitat variation on the space-use responses of GPS-collared wolves to linear features in eastern Manitoba. We simultaneously model wolf movement and selection within a conditional logistic regression framework (integrated Step Selection Analysis) with explicit consideration for how habitat alters these responses through either added cover or friction to movement. Classifying linear features based on the selection and movement response of wolves revealed that pairing transmission lines and primary roads increased the avoidance response to be greater than either feature on their own and provided evidence of a semi-permeable barrier to movement. In contrast, features with reduced human activity, including secondary and tertiary roads were highly selected for and provided access to movement corridors. Explicit parameterization of habitat provides evidence that where a linear feature is routed and which habitats it interacts with will have the greatest implications for wolf behavioural responses. Reduction of avoidance behavioural in highly risky environments signifies the importance of habitat for maintaining landscape connectivity, particularly when routing multiple features together. Natural regrowth along these features reduced movement advantages by increasing friction, indicating that actively decommissioning other features such as secondary roads would have important implications for reducing wolf encounters with prey. Knowing the influence of adjacent habitats on the likelihood of wolves selecting for a given linear feature creates context to minimize the impact of new anthropogenic features on behaviour.

ecology↗

bioRxiv2023

Hunger drives switching and searching response in a social predator

AO_SCPLOWBSTRACTC_SCPLOWHunger is a frequent state for many predators and increasing hunger is likely to motivate costly behaviour to acquire necessary resources. Generalist predators must balance the costs and gains of hunting different prey, including increasing encounter rates and improving success rates by seeking areas with greater prey catchability. Large carnivores face threats when they interact with humans or conspecifics. We use integrated step selection analysis to describe spatiotemporal factors that influence wolf (Canis lupus) hunting behavior in Riding Mountain National Park, a natural area that wolves share with moose (Alces alces) and elk (Cervus canadensis). If hunger generates more risky behavior by wolves, as time-from-kill increases we expect wolves will: (1) search for and kill a prey that poses higher risk of injury, (2) use the periphery of their range, (3) use areas closer to the park boundary. Hunger alters wolf space use and drives a fine scale change in prey tracking. Movement patterns of hungry wolves are indicative of search behavior, i.e., shorter steps and more turning. Contrary to our predictions, hungry wolves moved further into the park. As wolves become hungrier, they switch their response from a weak selection to avoidance of elk. In contrast, the response to the primary and emergent prey, moose varied between individuals with some pack level similarities. Therefore, the state-based response to a pervasive risk and a historical resource was conserved in a population residing in a prey rich island interfacing with human disturbance.

ecology↗

bioRxiv2023

Foraging decisions of snowshoe hares in response to experimentally induced coat-colour mismatch

Animals may exhibit various strategies to mitigate the adverse effects of phenological mismatch. In species experiencing coat colour mismatch, the effects of lost camouflage on the susceptibility to predation may be compensated for with other antipredator traits, such as altered foraging decisions, and may further depend on the intensity of risk. We artificially simulated coat colour mismatch and predation risk in wild-caught snowshoe hares and measured their forage intake rate of black spruce browse, intraspecific selection for forage quality, i.e., % nitrogen of browse, and resulting body mass loss across different risk levels, simulated by cover or lack thereof. We found that hares did not adjust their intake rate in response to mismatch, but hares in our high-risk treatment ate significantly more than hares in our low-risk treatment. Mismatched brown hares, however, selected for more nitrogen-rich forage than their matched brown counterparts. Mismatched white hares lost 4.55% more body mass than their matched white counterparts, despite not reducing their intake rate. Hares in our high-risk treatment lost 1.29% more body mass than those in covered enclosures. We suggest that the increased selection for nitrogen-rich forage observed in brown mismatched hares may occur to mitigate the body mass loss consequences of mismatch. Similarly, the increased intake rate of hares in clear roof enclosures relative to those in opaque roof enclosures may be a compensatory behavioural response to increased body mass loss. Our results highlight the potential indirect effects of coat colour mismatch on snowshoe hares, but also the corresponding behavioural mechanisms that may partially mitigate these effects.

ecology↗

bioRxiv2023

Animal-vectored nutrient flows across resource gradients influence the nature of local and meta-ecosystem functioning

Organisms moving across landscapes connect ecosystems in space and time, mediating nutrient, energy, and biomass exchanges. Meta-ecosystem ecology offers a framework to study how these flows affect ecosystem functions in space and time. However, meta-ecosystem models often represent consumer movement as diffusion along gradients of resources. Crucially, this assumes that consumer movement connects the same trophic compartments among patches of the same ecosystem. Yet, empirical evidence shows that organisms move across different ecosystems and connect diverse trophic compartments in diffusive and non-diffusive ways. Here, we derive a two-patch meta-ecosystem model that accounts for both types of organismal movement, and we investigate their influences on local and meta-ecosystem functions. We integrate two novel approaches in this classic meta-ecosystem model: a dispersers pool to capture the fraction of moving organisms and time scales separation to partition local and regional dynamics. We show that non-diffusive consumer movement increases landscape heterogeneity while diffusive consumer movement enhances source-sink dynamics. Local ecosystem differences driven by consumer movement type are less prevalent at meta-ecosystem extents. Thus, movement type is essential for predicting local ecosystem dynamics. Our results support recent calls to explicitly consider the role of consumers in shaping and maintaining ecosystem functions in space and time.

ecology↗

bioRxiv2022

Environmental, social, and morphological drivers of fission-fusion dynamics in a social ungulate

Social groups exist because individuals within the group accrue a net benefit from sharing space. The profitability of sociality, however, varies with ecological context. As ecological context varies, tension emerges among the costs and benefits of social grouping. Fission-fusion societies are fluid in their group dynamics across spatial and temporal contexts, permitting insights into how context affects whether animals choose to join or depart a group. We tested four non-mutually exclusive hypotheses driving variation in fission and fusion in caribou: the risky places, environment heterogeneity, activity budget, and social familiarity hypotheses. The risky places hypothesis predicts animals are unlikely to diffuse when habitats are open and risk of predation is elevated. The habitat heterogeneity hypothesis predicts that fission is more likely in a heterogeneous landscape due to the rising conflicts of interest between group members. The activity budget hypothesis predicts dyads associate by body size due to similar food passage rates. The social cohesion hypothesis predicts that familiar individuals are less likely to fission. We tested the hypotheses using time-to-event (time before fission) analyses and a linear model that assesses spatial, social, and body size relationships among female caribou (n = 22) on Fogo Island, Newfoundland, Canada. Contrary to our prediction for risky places, probability of fission was not influenced by habitat openness. The hypothesis of environmental heterogeneity was partially supported, as caribou remained less cohesive in environments with a higher richness of habitats. No direct evidence emerged to support the activity budget hypothesis. However, it appears that caribou maintain the strongest social bonds among variably sized individuals and these social bonds do decrease the propensity to split. Collectively, our findings showed that social interactions may depend not only on individual identity and characteristics, but also the spatial context in which these interactions occur.

animal behavior and cognition↗

bioRxiv2022

Unifying adaptive stress and adaptive habitat selection hypotheses through movement ecology

The cort-adaptation and cort-fitness hypotheses both propose glucocorticoids produced by parents mediate trade-offs between their own survival and that of their offspring. The contribution of glucocorticoids to offspring provisioning can quantify these trade-offs because provisioning poses a risk to parents. However, attributing provisioning behaviour to glucocorticoids is difficult because glucocorticoids often drive foraging behaviours to store energy for later provisioning. We compared the effects of glucocorticoids on habitat selection before and after calving to test for the trade-offs female elk make when provisioning offspring. Despite finding that female elk with elevated glucocorticoids selected more strongly for high-risk, high-forage cropland, we found no difference in glucocorticoid production nor a significant change in the effect of glucocorticoids on cropland selection at calving time when lactating elk required the more energy. However, we found a gradual increase in the effect of glucocorticoids on cropland selection by female elk as their calves grew, suggesting the growing energy requirements of calves encouraged more risky habitat selection behaviours by their parents over time. We suggest trade-offs in investment between parents and offspring across life history stages can be tested by integrating glucocorticoids into habitat selection models. Ultimately, this integration will help elucidate the adaptive function of glucocorticoids.

ecology↗

bioRxiv2021

At a snail's pace: the influence of habitat disturbance on terrestrial snail movement using experimentally manipulated mesocosms

The Anthropocene marks great changes to environments and the animals that inhabit them. Changes, such as disturbance, can affect the manner in which animals interact with their environments, such as moving and selecting habitats. To test how animals might respond to changing disturbance regimes, we employ an experimental approach to movement ecology. We used integrated step selection analysis (iSSA) to test the behavioural responses of individually-marked grove snails (Cepaea nemoralis) exposed to a gradient of physical disturbance in their habitat. We used a before-after control-impact (BACI) experimental design within semi-controlled mesocosms to manipulate edge and disturbance variables by altering the area of the mesocosm covered by bricks. We showed that grove snails perceive edges of enclosures and edges of bricks as risks, and responded to such risks by altering their movement. Grove snails displayed a bimodal response to risk by taking shelter in place or moving faster to be farther from the disturbance. Furthermore, individuals tended to modulate their behavioural response to the degree of risk. Our study highlights the usefulness of experimental mesocosms in movement ecology and in determining the effects of habitat alteration and human-imposed risk on movement behaviour.

animal behavior and cognition↗

bioRxiv2021

Coat color mismatch improves survival of a keystone boreal herbivore: energetic advantages exceed lost camouflage

Climate warming is causing asynchronies between animal phenology and environments. Mismatched traits, like coat color change mismatched with snow, can decrease survival. However, coat change does not serve a singular adaptive benefit of camouflage, and alternate coat change functions may confer advantages that supersede mismatch costs. We found that mismatch reduced rather than increased, autumn mortality risk of snowshoe hares in Yukon by 86.5 %. We suggest that the increased coat insulation and lower metabolic rates of winter acclimatized hares confer energetic advantages to white mismatched hares that reduce their mortality risk. We found that white mismatched hares forage 17-77 minutes less per day than matched brown hares between 0 and -10 {degrees}C, thus lowering their predation risk and increasing survival. We found no effect of mismatch on spring mortality risk, where mismatch occurred at warmer temperatures, suggesting a potential temperature limit where the costs of conspicuousness outweigh energetic benefits.

ecology↗

bioRxiv2021

Plasticity and repeatability in spring migration and parturition dates with implications for annual reproductive success

Animals are faced with unprecedented challenges as environmental conditions change. Animals must display behavioral plasticity to acclimate to changing conditions, or phenotypic variation must exist within the population to allow for natural selection to change the distribution of trait values. The timing of migration and parturition relative to important annual environmental changes such as snowmelt and vegetation green-up and how they co-vary may influence reproductive success. We tested for plasticity and individual differences in migration and parturition timing as a function of the timing of snowmelt and green-up in a migratory herbivore (caribou; Rangifer tarandus, n = 92) using behavioral reaction norms. We tested whether timing of parturition, plasticity in parturition timing, or timing of green-up were correlated with calf survival. Migration and parturition timing were plastic to the timing of spring conditions, and we found moderate repeatability for migration timing, but no repeatability in timing of parturition. We detected a novel behavioral syndrome where timing of migration and timing of parturition were correlated. Our results suggest that observed shifts in caribou parturition timing in other populations are due to plasticity as opposed to an evolutionary response to changing conditions. We did not detect a correlation between annual reproductive success and either the timing of spring or plasticity to the timing of spring events. While this provides evidence that many populations may be buffered from the consequences of climate change via plasticity, we caution that a lack of repeatability in parturition timing could impede adaptation as climate warming increases. Significance StatementAnimals have evolved to reproduce when resources are abundant. Climate change has altered the timing of annual events, resulting in earlier peaks in resource abundance. Animals can cope with this change in two ways. Individuals can display plasticity and alter the timing of reproductive activities to match the change in the environment, or consistent differences among individuals can result in sufficient variation to drive an evolutionary response. We tested these two alternative hypotheses in caribou (Rangifer tarandus) using an individual-based modelling framework. Caribou displayed plasticity in both when they migrated and gave birth, suggesting they can acclimate to changing conditions, but we did not find evidence of differences among individuals that would be likely to result in an evolutionary response.

ecology↗