Habitat Selection In Response Research Articles

Wolf habitat selection in relation to recreational structures in a national park

AbstractAlthough most predators usually avoid human activity, some individuals instead will habituate to it. Habituation to human presence and infrastructure by predator species such as wolves may lead to conflicts implicating serious risks for public safety and for the survival of the animals involved. Accordingly, this research project aims to shed light on the relationship between wolves and recreational structures using telemetry data from 10 wolves located in the Parc National du Mont-Tremblant (Québec, Canada) and its surrounding area. Using resource selection functions (RSFs), we observed wolf habitat selection in relation to these structures during three biological periods (denning: May–June; rendezvous: June–October; and nomadic: October–April). Our results revealed that wolves selected proximity to linear structures (roads and trails) during the denning and rendezvous periods, but this selection depended on the density of such structures in the surroundings (i.e., functional response in habitat selection): wolves selected proximity to linear structures when these structures were present at greater densities. Wolves avoided housing structures (campsites, cabins, park facilities), especially when these structures were present at greater densities, suggesting that wolves perceived them as a risk. These results suggest that conflicts between visitors and wolves were unlikely to occur in campgrounds during the time of our study. This could indicate that the management measures implemented by the park following the past episodes of conflict were effective. However, wolves’ use of linear structures could lead to increased tolerance to human proximity if left unmanaged.

Local and Landscape Analyses of Habitat Selection of South Carolina Clapper Rails (Rallus crepitans)

The Clapper Rail (Rallus crepitans) is an avian marsh specialist that depends exclusively on coastal wetlands for all aspects of its life cycle, and is valued for its role as an indicator of ecosystem health. This study used radio telemetry in the Ashepoo-Combahee-Edisto Basin in South Carolina, USA, to assess Clapper Rail habitat selection in response to local and landscape variables and to investigate possible demographic consequences of differences in habitat selection. Compared to simulated home ranges, observed Clapper Rail home ranges during the breeding season contained greater amounts of potential forage area and shorter distances to potential forage locations at both local and landscape scales. Mean (± SE) Clapper Rail home range size was 1.06 ha ± 0.19. There were no significant differences between males (1.05 ha ± 0.26) and females (1.08 ha ± 0.25) in home range size. Home range selection based on optimization of potential forage resources may have demographic consequences for Clapper Rails; however, this hypothesis was only weakly supported. Clapper Rails foraging near exposed edges may increase mortality risk through predation, but this behavior may be negligible to survival provided that sufficient nearby cover exists. Resource abundance near cover is likely a major driver of habitat selection and is influencing Clapper Rail habitat selection at multiple scales, which may have consequences for adult survival.

The density of anthropogenic features explains seasonal and behaviour-based functional responses in selection of linear features by a social predator

Anthropogenic linear features facilitate access and travel efficiency for predators, and can influence predator distribution and encounter rates with prey. We used GPS collar data from eight wolf packs and characteristics of seismic lines to investigate whether ease-of-travel or access to areas presumed to be preferred by prey best explained seasonal selection patterns of wolves near seismic lines, and whether the density of anthropogenic features led to functional responses in habitat selection. At a broad scale, wolves showed evidence of habitat-driven functional responses by exhibiting greater selection for areas near low-vegetation height seismic lines in areas with low densities of anthropogenic features. We highlight the importance of considering landscape heterogeneity and habitat characteristics, and the functional response in habitat selection when investigating seasonal behaviour-based selection patterns. Our results support behaviour in line with search for primary prey during summer and fall, and ease-of-travel during spring, while patterns of selection during winter aligned best with ease-of-travel for the less-industrialized foothills landscape, and with search for primary prey in the more-industrialized boreal landscape. These results highlight that time-sensitive restoration actions on anthropogenic features can affect the probability of overlap between predators and threatened prey within different landscapes.

Functional response of wolves to human development across boreal North America.

AimThe influence of humans on large carnivores, including wolves, is a worldwide conservation concern. In addition, human‐caused changes in carnivore density and distribution might have impacts on prey and, indirectly, on vegetation. We therefore tested wolf responses to infrastructure related to natural resource development (i.e., human footprint).LocationOur study provides one of the most extensive assessments of how predators like wolves select habitat in response to various degrees of footprint across boreal ecosystems encompassing over a million square kilometers of Canada.MethodsWe deployed GPS‐collars on 172 wolves, monitored movements and used a generalized functional response (GFR) model of resource selection. A functional response in habitat selection occurs when selection varies as a function of the availability of that habitat. GFRs can clarify how human‐induced habitat changes are influencing wildlife across large, diverse landscapes.ResultsWolves displayed a functional response to footprint. Wolves were more likely to select forest harvest cutblocks in regions with higher cutblock density (i.e., a positive functional response to high‐quality habitats for ungulate prey) and to select for higher road density in regions where road density was high (i.e., a positive functional response to human‐created travel routes). Wolves were more likely to use cutblocks in habitats with low road densities, and more likely to use roads in habitats with low cutblock densities, except in winter when wolves were more likely to use roads regardless of cutblock density.Main conclusionsThese interactions suggest that wolves trade‐off among human‐impacted habitats, and adaptively switch from using roads to facilitate movement (while also risking encounters with humans), to using cutblocks that may have higher ungulate densities. We recommend that conservation managers consider the contextual and interacting effects of footprints when assessing impacts on carnivores. These effects likely have indirect impacts on ecosystems too, including on prey species.

Revisiting the functional response in habitat selection for large herbivores: a matter of spatial variation in resource distribution?

AbstractMost habitats are distributed heterogeneously in space, forcing animals to move according to both habitat characteristics and their needs for energy and safety. Animal space use should therefore vary according to habitat characteristics, a process known as the “functional response” in habitat selection. This response has often been tested vis-à-vis the proportion of a habitat category within areas available to individuals. Measuring sought-after resources in landscape where they are continuously distributed is a challenge and we posit here that both the mean availability of a resource and its spatial variation should be measured. Accordingly, we tested for a functional response in habitat selection according to these two descriptors of the resource available for a mountain herbivore. We hypothesized that selection should decrease with mean value of resources available and increase with its spatial variation. Based on GPS data from 50 chamois females and data on the actual foodscape (i.e., distribution of edible-only biomass in the landscape), we estimated individual selection ratio (during summer months) for biomass at the home range level, comparing edible biomass in individual home ranges and the mean and standard deviation of edible biomass in their available range. Chamois being a group-living species, available accessible ranges were shared by several individuals that formed socio-spatial groups (clusters) in the population. As expected, selection ratios increased with the standard deviation of edible resources in each cluster, but unlike our prediction, was unrelated to its mean. Selection of areas richer in resources hence did not fade away when more resources were available on average, a result that may be explained by the need for this capital breeder species to accumulate fat-reserve at a high rate during summer months. Low spatial variation could limit the selection of chamois, which highlights the importance of resource distribution in the process of habitat selection.

Global change-driven use of onshore habitat impacts polar bear faecal microbiota.

The gut microbiota plays a critical role in host health, yet remains poorly studied in wild species. Polar bears (Ursus maritimus), key indicators of Arctic ecosystem health and environmental change, are currently affected by rapid shifts in habitat that may alter gut homeostasis. Declining sea ice has led to a divide in the southern Beaufort Sea polar bear subpopulation such that an increasing proportion of individuals now inhabit onshore coastal regions during the open-water period ('onshore bears') while others continue to exhibit their typical behaviour of remaining on the ice ('offshore bears'). We propose that bears that have altered their habitat selection in response to climate change will exhibit a distinct gut microbiota diversity and composition, which may ultimately have important consequences for their health. Here, we perform the first assessment of abundance and diversity in the faecal microbiota of wild polar bears using 16S rRNA Illumina technology. We find that bacterial diversity is significantly higher in onshore bears compared to offshore bears. The most enriched OTU abundance in onshore bears belonged to the phylum Proteobacteria, while the most depleted OTU abundance within onshore bears was seen in the phylum Firmicutes. We conclude that climate-driven changes in polar bear land use are associated with distinct microbial communities. In doing so, we present the first case of global change mediated alterations in the gut microbiota of a free-roaming wild animal.

Habitat selection can reduce effects of extreme climatic events in a long-lived shorebird.

Changes in the frequency of extreme climatic events (ECEs) can have profound impacts on individual fitness by degrading habitat quality. Organisms may respond to such changes through habitat selection, favouring those areas less affected by ECEs; however, documenting habitat selection in response to ECEs is difficult in the wild due to the rarity of such events and the long-term biological data required. Sea level rise and changing weather patterns over the past decades have led to an increase in the frequency of coastal flooding events, with serious consequences for ground nesting shorebirds. Shorebirds therefore present a useful natural study system to understand habitat selection as a response to ECEs. We used a 32-year study of the Eurasian oystercatcher (Haematopus ostralegus) to investigate whether habitat selection can lead to an increase in nest elevation and minimize the impacts of coastal flooding. The mean nest elevation of H. ostralegus has increased during the last three decades. We hypothesized that this change has been driven by changes in H. ostralegus territory settlement patterns over time. We compared various possible habitat selection cues to understand what information H. ostralegus might use to inform territory settlement. There was a clear relationship between elevation and territory settlement in H. ostralegus. In early years, settlements were more likely at low elevations but in more recent years the likelihood of settlement was similar between high and low elevation areas. Territory settlement was associated with conspecific fledgling output and conspecific density. Settlement was more likely in areas of high density and areas with high fledgling output. This study shows that habitat selection can minimize the effects of increasingly frequent ECEs. However, it seems unlikely that the changes we observe will fully alleviate the consequences of anthropogenic climate change. Rates of nest elevation increase were insufficient to track current increases in maximum high tide (0.5 vs. 0.8cm/year). Furthermore, habitat selection cues that rely on information from previous breeding seasons (e.g. conspecific fledgling output) may become ineffective as ECEs become more frequent and environmental predictability is diminished.

Habitat drivers of endangered rorqual whales in a highly impacted upwelling region

Abstract Recent studies show that human impacts on marine ecosystems are threatening marine biodiversity. A greater emphasis on predicting how predators might respond to changes in the marine environment is needed because the effects of human activities are spatially heterogeneous. Here we analyse rorqual whales distribution data in a highly impacted upwelling region (North-western Iberian coast, Spain). Using a multi-model inference approach this study assesses the habitat drivers of the fine-scale distribution of three endangered whale species (blue, fin and sei whales) as a way to better understand how rorqual whales might respond to human-induced changes in the coastal ecosystem. The unequal use of available habitat, concentrated at the edge of the continental slope (200 m depth and strong bottom slope gradient) in areas with a south-easterly coastal orientation, showed that rorqual whales presented a fine-scale pattern of habitat selection in response to prey availability. Rorqual whales’ distribution is affected by the coastal upwelling regime of the Iberian Peninsula, which is known to be under impact of climate change. Therefore, responses of rorqual whales to upwelling changes might be manifested at the population level such as shifts in abundance and distribution. This information contributes to extend the scant information available about the presence of these species in the North-east Atlantic. Our findings provide management agencies with an opportunity to devise and implement adequate adaptation measures which may ameliorate adverse effects critical for the conservation of rorquals in a changing climate.

Functional responses in habitat selection: clarifying hypotheses and interpretations

A fundamental challenge in habitat ecology and management is understanding the mechanisms generating animal distributions. Studies of habitat selection provide a lens into such mechanisms, but are often limited by unrealistic assumptions. For example, most studies assume that habitat selection is constant with respect to the availability of resources, such that habitat use remains proportional to availability. To the contrary, a growing body of work has shown the fallacy of this assumption, indicating that animals modify their behavior depending on the context at broader scales. This has been termed a functional response in habitat selection. Furthermore, a diversity of methods is employed to model functional responses in habitat selection, with little attention to how methodology might affect scientific and conservation conclusions. Here, we first review the conceptual and statistical foundations of methods currently used to model functional responses and clarify the ecological tests evaluated within each approach. We then use a combination of simulated and empirical data sets to evaluate the similarities and differences among approaches. Importantly, we identified multiple statistical issues with the most widely applied approaches to understand functional responses, including: (1) a complex and important role of random- or individual-level intercepts in adjusting individual-level regression coefficients as resource availability changes and (2) a sensitivity of results to poorly informed individual-level coefficients estimated for animals with low availability of a given resource. Consequently, we provide guidance on applying approaches that are insensitive to these issues with the goal of advancing our understanding of animal habitat ecology and management. Finally, we characterize the management implications of assuming similarity between the current approaches to model functional responses with two empirical data sets of federally threatened species: Canada lynx (Lynx canadensis) in the United States and woodland caribou (Rangifer tarandus caribou) in Canada. Collectively, our assessment helps clarify the similarities and differences among current approaches and, therefore, assists the integration of functional responses into the mainstream of habitat ecology and management.

A time-lagged effect of conspecific density on habitat selection by snowshoe hare.

Ideal free distribution theory predicts that increased conspecific density redistributes individuals to low-density, suboptimal habitat. However, possible lags in response to population density remain poorly documented. Snowshoe hares (Lepus americanus) may exhibit density-dependent habitat selection due to its marked variation in population density. Based on 11 years (2004–2014) of snow tracking in Quebec (Canada), we investigated snowshoe hares’ short-term and delayed habitat selection responses to population density. We predicted that at high densities, hare distribution expands into low-density habitat, thus weakening the association between hares and high-density habitat. We surveyed hare tracks along 95 km of transects on average each year and georeferenced 14,240 tracks. We used Generalized Estimating Equations for track count per 100 m transect segment as a function of the proportion of different forest age classes (0–20 y, 20–40 y and 40–80 y) within 50 m of the segments. We used model coefficients for each age class as a measure of habitat preference, and modeled those coefficients as a function of a population density index in current and previous winters. Coefficients for 20- to 40-y-old forests were positive each year, indicating that this habitat was preferred. The association between track counts and 20- to 40-y-old forest significantly declined with density during the previous winter, suggesting that hare spread from preferred forest with a lagged response to density. To our knowledge, no previous empirical studies have documented a lagged habitat selection response to population density. Time lags offer possible explanation for documented deviations from ideal free distribution models.

Effects of biopesticides on oviposition site selection in invasive and native mosquitoes in southeastern Pennsylvania

Abstract Ecological and economic harm by invasive species is exemplified by some Aedes mosquitoes. Their pathogen transmission to humans and wildlife has generated much research concerning how biopesticides induce larval mortality. The response of ovipositing females to biopesticides is less well understood and shows inter- and intraspecific variation. Quantifying this variation is crucial for reducing vector populations and disease outbreaks. We examined how invasive (Aedes albopictus and A. japonicus) and native (Culex restuans) ovipositing mosquitoes responded to the presence of Bacillus thuringiensis israelensis (BTI), B. sphaericus (BS), their combination, and controls lacking biopesticides and how this affected larval survivorship. A. albopictus females laid more eggs at control sites (p = 0.0005), C. restuans deposited more eggs with biopesticides (p < 0.0001), and A. japonicus did not respond to treatments when laying eggs (p = 0.3128). Larval survivorship with biopesticides was 0.0% in all species (p < 0.0001). Female avoidance suggests that behavioral resistance to biopesticides can occur at oviposition (A. albopictus); attraction (C. restuans) or no response (A. japonicus) could generate ecological traps. Oviposition habitat selection in response to biopesticides varies within and among species and might reduce or enhance larval mortality, population abundance, and the success of vector control programs.

Functional responses in animal movement explain spatial heterogeneity in animal-habitat relationships.

Understanding why heterogeneity exists in animal-habitat spatial relationships is critical for identifying the drivers of animal distributions. Functional responses in habitat selection - whereby animals adjust their habitat selection depending on habitat availability - are useful for describing animal-habitat spatial heterogeneity. However, they could be yielded by different movement tactics, involving contrasting interspecific interactions. Identifying functional responses in animal movement, rather than in emergent spatial patterns like habitat selection, could disentangle the effects of different movement behaviours on spatial heterogeneity in animal-habitat relationships. This would clarify how functional responses in habitat selection emerge and provide a general tool for understanding the mechanistic drivers of animal distributions. We tested this approach using data from GPS-collared woodland caribou (Rangifer tarandus), a prey species under top-down control. We tested how caribou selected and moved with respect to a key resource (lichen-conifer stands) as a function of the availability of surrounding refuge land-cover (closed-conifer stands), using step selection functions. Caribou selected resource patches more strongly in areas richer in refuge land-cover - a functional response in habitat selection. However, adjustments in multiple movement behaviours could have generated this pattern: stronger directed movement towards resource patches and/or longer residency within resource patches, in areas richer in refuges. Different contributions of these behaviours would produce contrasting forager spatial dynamics. We identified functional responses in both movement behaviours: caribou were more likely to move towards resource patches in areas richer in refuge land-cover, and to remain in these patches during movement steps. This tactic enables caribou to forage for longer in safer areas where they can rapidly seek refuge in dense cover when predators are detected. Our study shows that functional responses in movement can expose the context-dependent movement decisions that generate heterogeneity in animal-habitat spatial relationships. We used these functional responses to characterise anti-predator movement tactics employed by a large herbivore, but they could be applied in many different scenarios. The movement rules from functional responses in movement are well-suited to integration in spatial explicit individual-based models for forecasting animal distributions in landscapes undergoing environmental change.

Wolverine habitat selection in response to anthropogenic disturbance in the western Canadian boreal forest

We evaluated alternative hypotheses that anthropogenic disturbance can attract versus displace wolverines (Gulo gulo luscus). Our research took place in boreal forests of northwestern Alberta where we employed radiotelemetry to track wolverine habitat use over three years. We used resource selection functions (used/available design) to analyze wolverine habitat selection patterns during summer and winter seasons. We focused our analyses on the effects of active logging, intermediate-aged cutblocks (11–25years old), seismic lines, roads, and borrow pits on wolverine habitat selection. Our analysis of active logging used a before, during, interim, and after design. We found wolverines were attracted to logging areas. The strongest selection for logged areas occurred during logging and in the following summer. We suggest logged areas provide foraging opportunities and movement routes for wolverines. Male wolverines were attracted to the edges of intermediate-aged cutblocks (11–25years old) during summer whereas females were attracted to cutblock edges in winter. However, females avoided intermediate-aged cutblock edges in summer. Moreover, both male and female wolverines avoided the interior of these cutblocks. We would suggest that cutblock edges can provide wolverines with foraging opportunities. We also found wolverines were attracted to seismic lines and borrow pits along roads. Regenerating seismic lines and borrow pits (inhabited by beavers) might offer wolverines foraging opportunities. Our research highlights the need for managers to appreciate the potential for anthropogenic disturbance to either attract or repel wolverines. We warn that attraction of wolverines to industrial features might lead to increased mortality. We also stress that the age of a disturbance can influence its effect on wolverines.

Moving beyond the plane: measuring 3D home ranges of juvenile salamanders with passive integrated transponder (PIT) tags

An individual’s home range, or how much space it requires to obtain resources and meet its needs for survival and reproduction, affects the scale of many fundamental processes in ecology and can inform the management of species. Although home range size has been described for many taxa in two dimensions (2D), for species that also have a strong vertical component to their movement, such representations can miss core components of their ecology, including the size of their home ranges and the amount of overlap, and thus competition, between individuals. Measuring three-dimensional (3D) home ranges for small-bodied life history stages and species can be particularly difficult, as they cannot tolerate high resolution tracking technologies like GPS collars. In this study, we used Passive Integrated Transponder (PIT) tags to measure the 2D and 3D home ranges of two species of fossorial juvenile salamander: the ringed salamander (Ambystoma annulatum) and the spotted salamander (A. maculatum). We also tested whether individuals modified their habitat selection or movement behavior in response to environmental variation. Salamanders in our study frequently used subterranean habitats. However, we rarely detected them more than 5 cm below ground. Additionally, the overlap among 2D and 3D home ranges, respectively, were similar. These findings indicate that these salamanders may move vertically through their habitat less than previously thought. Alternatively, salamanders may have moved into soil strata beyond the detection range of PIT telemetry. We conclude that PIT telemetry can be a suitable technique for determining the 3D home range of fossorial life-stages or species for which other tracking technologies are unsuitable. When animal behavior includes movements with a vertical component, simplifying assumptions of 2D home ranges can affect ecological inferences by overestimating competition between individuals and underestimating home range size. We used Passive Integrated Transponder (PIT) tags to describe the home range of fossorial juvenile salamanders in 3D. The juvenile salamanders in this study modulated their habitat selection in response to weather, but in general remained close to the soil surface. As a result, juveniles may be more susceptible than previously thought to habitat management practices that alter the local microclimate. Because individuals moved vertically less than predicted, 2D and 3D home ranges had similar patterns. We demonstrate that PIT telemetry can facilitate subterranean tracking of a cryptic life stage. However, this technology is limited in its subterranean detection depth, and until antenna strength is improved, the resolution of 3D home ranges may be limited.

Does riparian disturbance alter stream amphibian antipredator behaviors?

Ecological traps occur when a species makes maladaptive habitat-selection decisions. Human-modified environments including deforested riparian habitats can change how organisms respond to environmental cues. Stream amphibians alter their habitat selection in response to abiotic cues associated with riparian clearing, but little research exists to determine if behavioral shifts to abiotic cues may make them more susceptible to predation. To evaluate if deforested habitats create ecological traps, we studied habitat-selection behavior of larval Black-bellied Salamander (Desmognathus quadramaculatus (Holbrook, 1840)) when given conflicting environmental cues. We also evaluated the potential for learning or adaptation to cues in deforested reaches by evaluating individuals from forested and deforested reaches. We anticipated that individuals from deforested reaches would make adaptive antipredator choices when presented with well-lit habitat, whereas individuals from forested reaches would select shaded habitat closer to a predator. We found that habitat origin, light, and predator presence all interacted to influence habitat selection. Although individuals from forested habitats selected shaded environments, all observed individuals adaptively avoided a predator. Individuals from deforested reaches were more willing to enter well-lit habitat to avoid the predator. Despite documented declines of salamanders associated with forest removal, it appears that individuals are capable of making adaptive antipredator decisions in degraded habitats.

Indirect predation management in a longleaf pine ecosystem: Hardwood removal and the spatial ecology of raccoons

Raccoons (Procyon lotor) are native and ubiquitous throughout much of the continental United States and are invasive in many countries around the world. Where they occur, raccoons are a known predator of ground-nesting birds and herpetofauna. Raccoons often are associated with hardwood trees; therefore, hardwood reduction in open pine (Pinus spp.) forests of the southeastern U.S. may reduce raccoon use while providing suitable habitat for upland ground-nesting species. As a result, some have suggested removal of undesirable hardwoods as a means to manage nest predation by altering raccoon behavior. However, effects of operationally removing hardwoods from an open pine matrix on raccoon home range size and habitat selection are unknown. We compared home range sizes and habitat selection of adult raccoons in a longleaf pine (Pinus palustris) dominated forest before and after large-scale, operational hardwood removal. Male raccoons had larger (P<0.001) home ranges than females, but home range sizes did not differ (P=0.54) by period (i.e., before or after hardwood removal). However, raccoon habitat selection at the home range scale varied (P=0.02) between periods as did selection of habitats within the home range (P=0.01). When selecting areas for home ranges, raccoons had greater (P=0.01) affinity for young pine stands following operational hardwood removal. Within the home range, raccoons increased (P=0.01) selection for wetlands and decreased (P=0.02) selection for primary roads following hardwood removal. Raccoon habitat selection within the home range did not vary (P=0.39) seasonally. Pine forests were important when establishing home ranges during both periods, but other habitats (i.e., secondary roads, young pine, hardwood, and mixed pine-hardwood) became equally as important as pine following hardwood removal. Within the home range, hardwood stands remained the most important habitat feature before and after hardwood removal. Our results suggest that raccoons alter habitat selection in response to hardwood removal, which may affect patterns of nest predation by raccoons.

Habitat functional response mitigates reduced foraging opportunity: implications for animal fitness and space use

Animals selectively use landscapes to meet their energetic needs, and trade-offs in habitat use may depend on availability and environmental conditions. For example, habitat selection at high temperatures may favor thermal cover at the cost of reduced foraging efficiency under consistently warm conditions. Our objective was to examine habitat selection and space use in distinct populations of moose (Alces alces). Hypothesizing that endotherm fitness is constrained by heat dissipation efficiency, we predicted that southerly populations would exhibit greater selection for thermal cover and reduced selection for foraging habitat. We estimated individual step selection functions with shrinkage for 134 adult female moose in Minnesota, USA, and 64 in Ontario, Canada, to assess habitat selection with variation in temperature, time of day, and habitat availability. We averaged model coefficients within each site to quantify selection strength for habitats differing in forage availability and thermal cover. Moose in Ontario favored deciduous and mixedwood forest, indicating selection for foraging habitat across both diel and temperature. Habitat selection patterns of moose in Minnesota were more dynamic and indicated time- and temperature-dependent trade-offs between use of foraging habitat and thermal cover. We detected a scale-dependent functional response in habitat selection driven by the trade-off between selection for foraging habitat and thermal cover. Landscape composition and internal state interact to produce complex patterns of space use, and animals exposed to increasingly high temperatures may mitigate fitness losses from reduced foraging efficiency by increasing selection for foraging habitat in sub-prime foraging landscapes.

Quantifying consistent individual differences in habitat selection.

Habitat selection is a fundamental behaviour that links individuals to the resources required for survival and reproduction. Although natural selection acts on an individual's phenotype, research on habitat selection often pools inter-individual patterns to provide inferences on the population scale. Here, we expanded a traditional approach of quantifying habitat selection at the individual level to explore the potential for consistent individual differences of habitat selection. We used random coefficients in resource selection functions (RSFs) and repeatability estimates to test for variability in habitat selection. We applied our method to a detailed dataset of GPS relocations of brown bears (Ursus arctos) taken over a period of 6years, and assessed whether they displayed repeatable individual differences in habitat selection toward two habitat types: bogs and recent timber-harvest cut blocks. In our analyses, we controlled for the availability of habitat, i.e. the functional response in habitat selection. Repeatability estimates of habitat selection toward bogs and cut blocks were 0.304 and 0.420, respectively. Therefore, 30.4 and 42.0% of the population-scale habitat selection variability for bogs and cut blocks, respectively, was due to differences among individuals, suggesting that consistent individual variation in habitat selection exists in brown bears. Using simulations, we posit that repeatability values of habitat selection are not related to the value and significance of β estimates in RSFs. Although individual differences in habitat selection could be the results of non-exclusive factors, our results illustrate the evolutionary potential of habitat selection.

Grain-dependent functional responses in habitat selection

Context Spatial scale is an important consideration for understanding how animals select habitat, and multi-scalar designs in resource selection studies have become increasingly common. Despite this, examination of functional responses in habitat selection at multiple scales is rare. The perceptual range of an animal changes as a function of vegetation association, suggesting that use, selection and functional responses may all be habitat- and scale-dependent.

Stream Salamanders Accurately Assess Size-Dependent Predation Threats

Individual size is an important determinant of the outcomes of inter- and intraspecific interactions. Different-sized members of a guild might represent prey, competitors, or predators. Although direct predation rates might be low, trait-mediated indirect effects of predators on prey can yield altered activity, microhabitat use, survival, and growth. If individuals respond to all sizes of a predator regardless of the predation threat, antipredator behaviors might incur costs for prey as they forgo foraging opportunities or experience predation by other predators. Accurate assessment of predation risk would minimize costs resulting from antipredator behavior. We evaluated the ability of larval salamanders to assess predation risk and alter their habitat selection in response to intraguild competitors and predators. Specifically, we assessed behavioral responses to the presence of a conspecific, a similarly sized heterospecific, and a small or large individual of a predatory species. We predicted that larval salamanders would select habitat differently in the presence of a large predatory heterospecific, but not in the presence of similarly sized heterospecifics or conspecifics. The focal species occupied habitat 29 6 0.02% farther from a large heterospecific predator than from small heterospecifics, even if the heterospecifics were smaller individuals of the predatory species. The focal species also exhibited escape behaviors only in the presence of the large members of the predatory species. These data indicate that salamander larvae can assess size-specific predation threats, minimizing predation risk through use of antipredator behaviors.