Search

Understanding social relationships in at-risk species held in captivity is vital for their welfare and potential reintroduction. In social species like the Przewalski's horse ( Equus ferus przewalskii ), daily time allocation and space use may be influenced by social structure and, in turn, reflect welfare. Here, we identify social relationships, time budgets, and spatial distribution of a group of nine older (aged 6-21 years) male Przewalski's horses living in a non-breeding (bachelor) group. We conducted our work at the Askania-Nova Biosphere Reserve, over 65 h of observation in summer, 2015. Horses formed stronger social bonds with individuals of similar gregariousness and dominance levels. Social-network analysis identified three distinct subgroups with significant differences in locomotion, social behaviour, and foraging. However, resting and vigilance behaviour remained similar across the subgroups. Behavioural synchrony across all activities was higher within subgroups than between. Space use was also affected by subgroup membership, with some horses overusing or underusing critical resource areas like hay and water. These findings suggest opportunities to improve welfare by adjusting space and resource distribution, particularly for more submissive individuals. Our approach may also aid in selecting reintroduction candidates by considering social characteristics alongside health, genetic, and other factors.

Identifying factors that drive among-individual variation in mixed parasitic infections is fundamental to understanding the ecology and evolution of host–parasite interactions. However, a lack of non-invasive diagnostic tools to quantify mixed infections has restricted their investigation for host populations in the wild. This study applied DNA metabarcoding on parasite larvae cultured from faecal samples to characterize mixed strongyle infections of 320 feral horses on Sable Island, Nova Scotia, Canada, in 2014 to test for the influence of host (age, sex and reproductive/social status) and environmental (location, local density and social group membership) factors on variation. Twenty-five strongyle species were identified, with individual infections ranging from 3 to 18 species with a mean richness (±1 s.d.) of 10.8 ± 3.1. Strongyle eggs shed in faeces were dominated by small strongyle (cyathostomins) species in young individuals, transitioning to large strongyles ( Strongylus spp.) in adults. Egg counts were highest in young individuals and in the west or centre of the island for most species. Individuals in the same social group had similar parasite communities, supporting the hypothesis that shared environment may drive parasite assemblages. Other factors such as local horse density, sex, date and reproductive/social status had minimal impacts on infection patterns. This study demonstrates that mixed infections can be dynamic across host ontogeny and space and emphasizes the need to consider species-specific infection patterns when investigating mixed infections.

Animals within social groups respond to costs and benefits of sociality by adjusting the proportion of time they spend in close proximity to other individuals in the group (cohesion). Variation in cohesion between individuals, in turn, shapes important group-level processes such as subgroup formation and fission-fusion dynamics. Although critical to animal sociality, a comprehensive understanding of the factors influencing cohesion remains a gap in our knowledge of cooperative behavior in animals. We tracked 574 individuals from six species within the genus Canis in 15 countries on four continents with GPS telemetry to estimate the time that pairs of individuals within social groups spent in close proximity and test hypotheses regarding drivers of cohesion. Pairs of social canids (Canis spp.) varied widely in the proportion of time they spent together (5%-100%) during seasonal monitoring periods relative to both intrinsic characteristics and environmental conditions. The majority of our data came from three species of wolves (gray wolves, eastern wolves, and red wolves) and coyotes. For these species, cohesion within social groups was greatest between breeding pairs and varied seasonally as the nature of cooperative activities changed relative to annual life history patterns. Across species, wolves were more cohesive than coyotes. For wolves, pairs were less cohesive in larger groups, and when suitable, small prey was present reflecting the constraints of food resources and intragroup competition on social associations. Pair cohesion in wolves declined with increased anthropogenic modification of the landscape and greater climatic variability, underscoring challenges for conserving social top predators in a changing world. We show that pairwise cohesion in social groups varies strongly both within and across Canis species, as individuals respond to changing ecological context defined by resources, competition, and anthropogenic disturbance. Our work highlights that cohesion is a highly plastic component of animal sociality that holds significant promise for elucidating ecological and evolutionary mechanisms underlying cooperative behavior., (© 2024 The Author(s). Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

Gut microbiomes are widely hypothesised to influence host fitness and have been experimentally shown to affect host health and phenotypes under laboratory conditions. However, the extent to which they do so in free-living animal populations and the proximate mechanisms involved remain open questions. In this study, using long-term, individual-based life history and shallow shotgun metagenomic sequencing data (2394 fecal samples from 794 individuals collected between 2013-2019), we quantify relationships between gut microbiome variation and survival in a feral population of horses under natural food limitation (Sable Island, Canada), and test metagenome-derived predictions using short-chain fatty acid data. We report detailed evidence that variation in the gut microbiome is associated with a host fitness proxy in nature and outline hypotheses of pathogenesis and methanogenesis as key causal mechanisms which may underlie such patterns in feral horses, and perhaps, wild herbivores more generally., (© 2024. The Author(s).)

Cortisol is a glucocorticoid hormone produced during activation of the hypothalamic-pituitary-adrenal axis (HPA) in response to psychological or physiological demands. High amounts of circulating cortisol can be found in individuals experiencing energetically demanding physiological events, such as pregnancy, lactation, injury, or starvation, but, also, in individuals who may have less obvious HPA activation from social situations. The feral horse population on Sable Island (Nova Scotia, Canada) provides an opportunity to look at hair cortisol concentration (HCC) as a proxy for circulating cortisol concentration to better understand physiological correlates. The horse's complex social structure also allows us to look at how the population and group structure may influence HPA activation. Hair samples ( n = 282) were analyzed from 113 females and 135 males. Females with dependent offspring (foals) had higher HCC than those females without dependent offspring ( p = 0.005). Horses in poor body condition were also more likely to have higher HCC (females: p < 0.001, males: p = 0.028); females had greater variation in the body condition index (BCI), which also correlated with foal production. In general, the top-ranked models describing female cortisol levels included age, BCI, presence of a foal, as well as social measures such as harem size and the number of bachelors in the vicinity. The top model describing male cortisol levels included age, BCI, and year of collection only, and the number of bachelors in the home range appeared in subsequent, though still high-ranked, models. Among the variables not of direct interest, we found some significant results relating to hair color and hair texture. Differences in HCC patterns between feral and domestically kept horses (e.g., age and sex) are likely linked to periods of resource limitations, particularly for individuals experiencing energetically demanding processes such as reproduction, illness/parasitism, or related to experiencing the full range of social and reproductive behaviors.

Steroid-hormone concentrations from non-invasively obtained biomarkers, like hair, can provide a representation of circulating hormones diffused over relatively long time periods (e.g., weeks or months). The hormone cortisol is often associated with physiological or even psychological stress, while testosterone is strongly associated with male development and reproductive success. Increasingly, studies are using hormone levels derived from hair to make inferences among both domestic animals and wildlife. For horses, all previous hair hormone analysis has been done on companion or working animals. We evaluated the levels of hair cortisol ( n = 153) and testosterone ( n = 48) from 136 feral horses living on Sable Island, Canada that have been part of a long-term individual-based study since 2008. This population has been undisturbed and unmanaged for over 50 years, and exhibits the natural social organization for horses, harem defense polygyny. Hair samples were collected in mid to late summer and the segment analyzed corresponds with hair grown during, and following, the peak of the reproductive season. Social position was determined based on the male's role as either a dominant breeding Stallion (Stallion), a non-breeding subordinate male (tag), adult Bachelor (5 years old or older), or Immature male (2-4 years of age). While there was no difference in hair-cortisol concentration among any class of adult males (i.e., Stallion, tag, or Bachelor), Immature males had significantly lower hair cortisol concentrations than the other groups ( p = 0.001). Hair testosterone levels among the four social positions were significantly higher among Stallions ( p = 0.04). Hair testosterone concentration was also significantly related to the probability of a male being either a Bachelor or Stallion and was the only variable remaining in AIC c model selection ( p = 0.016, AIC c = 32.3, Null AIC c = 38.8). While not a significant relationship, Stallions had a negative correlation between hair cortisol concentrations and testosterone (R 2 = -0.20, p = 0.383), and Bachelors, conversely, had a positive association (R 2 = 0.43, p = 0.246). Our observations of hormone concentrations in relation to physiological, social, or reproductive parameters in this population suggest trends that are similar to what has been established using blood or other matrices.

Prevailing 16S rRNA gene-amplicon methods for characterizing the bacterial microbiome of wildlife are economical, but result in coarse taxonomic classifications, are subject to primer and 16S copy number biases, and do not allow for direct estimation of microbiome functional potential. While deep shotgun metagenomic sequencing can overcome many of these limitations, it is prohibitively expensive for large sample sets. Here we evaluated the ability of shallow shotgun metagenomic sequencing to characterize taxonomic and functional patterns in the faecal microbiome of a model population of feral horses (Sable Island, Canada). Since 2007, this unmanaged population has been the subject of an individual-based, long-term ecological study. Using deep shotgun metagenomic sequencing, we determined the sequencing depth required to accurately characterize the horse microbiome. In comparing conventional vs. high-throughput shotgun metagenomic library preparation techniques, we validate the use of more cost-effective laboratory methods. Finally, we characterize similarities between 16S amplicon and shallow shotgun characterization of the microbiome, and demonstrate that the latter recapitulates biological patterns first described in a published amplicon data set. Unlike for amplicon data, we further demonstrate how shallow shotgun metagenomic data provide useful insights regarding microbiome functional potential which support previously hypothesized diet effects in this study system., (© 2022 John Wiley & Sons Ltd.)

Background: Understanding inbreeding and its impact on fitness and evolutionary potential is fundamental to species conservation and agriculture. Long stretches of homozygous genotypes, known as runs of homozygosity (ROH), result from inbreeding and their number and length can provide useful population-level information on inbreeding characteristics and locations of signatures of selection. However, the utility of ROH for conservation is limited for natural populations where baseline data and genomic tools are lacking. Comparing ROH metrics in recently feral vs. domestic populations of well understood species like the horse could provide information on the genetic health of those populations and offer insight into how such metrics compare between managed and unmanaged populations. Here we characterized ROH, inbreeding coefficients, and ROH islands in a feral horse population from Sable Island, Canada, using ~41 000 SNPs and contrasted results with those from 33 domestic breeds to assess the impacts of isolation on ROH abundance, length, distribution, and ROH islands., Results: ROH number, length, and ROH-based inbreeding coefficients (F ROH ) in Sable Island horses were generally greater than in domestic breeds. Short runs, which typically coalesce many generations prior, were more abundant than long runs in all populations, but run length distributions indicated more recent population bottlenecks in Sable Island horses. Nine ROH islands were detected in Sable Island horses, exhibiting very little overlap with those found in domestic breeds. Gene ontology (GO) enrichment analysis for Sable Island ROH islands revealed enrichment for genes associated with 3 clusters of biological pathways largely associated with metabolism and immune function., Conclusions: This study indicates that Sable Island horses tend to be more inbred than their domestic counterparts and that most of this inbreeding is due to historical bottlenecks and founder effects rather than recent mating between close relatives. Unique ROH islands in the Sable Island population suggest adaptation to local selective pressures and/or strong genetic drift and highlight the value of this population as a reservoir of equine genetic variation. This research illustrates how ROH analyses can be applied to gain insights into the population history, genetic health, and divergence of wild or feral populations of conservation concern., (© 2022. The Author(s).)

The development of high-throughput sequencing has prompted a transition in wildlife genetics from using microsatellites toward sets of single nucleotide polymorphisms (SNPs). However, genotyping large numbers of targeted SNPs using non-invasive samples remains challenging due to relatively large DNA input requirements. Recently, target enrichment has emerged as a promising approach requiring little template DNA. We assessed the efficacy of Tecan Genomics' Allegro Targeted Genotyping (ATG) for generating genome-wide SNP data in feral horses using DNA isolated from fecal swabs. Total and host-specific DNA were quantified for 989 samples collected as part of a long-term individual-based study of feral horses on Sable Island, Nova Scotia, Canada, using dsDNA fluorescence and a host-specific qPCR assay, respectively. Forty-eight samples representing 44 individuals containing at least 10 ng of host DNA (ATG's recommended minimum input) were genotyped using a custom multiplex panel targeting 279 SNPs. Genotyping accuracy and consistency were assessed by contrasting ATG genotypes with those obtained from the same individuals with SNP microarrays, and from multiple samples from the same horse, respectively. 62% of swabs yielded the minimum recommended amount of host DNA for ATG. Ignoring samples that failed to amplify, ATG recovered an average of 88.8% targeted sites per sample, while genotype concordance between ATG and SNP microarrays was 98.5%. The repeatability of genotypes from the same individual approached unity with an average of 99.9%. This study demonstrates the suitability of ATG for genome-wide, non-invasive targeted SNP genotyping, and will facilitate further ecological and conservation genetics research in equids and related species., Supplementary Information: The online version contains supplementary material available at 10.1007/s12686-022-01259-2., Competing Interests: Conflict of interestNA., (© The Author(s) 2022.)

While the important role of animal-mediated interactions in the top-down restructuring of plant communities is well documented, less is known of their ensuing repercussions at higher trophic levels. We demonstrate how typically decoupled ecological interactions may become intertwined such that the impact of an insect pest on forest structure and composition alters predator-prey interactions among large mammals. Specifically, we show how irruptions in a common, cyclic insect pest of the boreal forest, the spruce budworm ( Choristoneura fumiferana ), modulated an indirect trophic interaction by initiating a flush in deciduous vegetation that benefited moose ( Alces alces ), in turn strengthening apparent competition between moose and threatened boreal caribou ( Rangifer tarandus caribou ) via wolf ( Canis lupus ) predation. Critically, predation on caribou postoutbreak was exacerbated by human activity (salvage logging). We believe our observations of significant, large-scale reverberating consumer-producer-consumer interactions are likely to be common in nature., Competing Interests: The authors declare no competing interest.

Horses are ubiquitously infected by a diversity of gastro-intestinal parasitic helminths. Of particular importance are nematodes of the family Strongylidae, which can significantly impact horse health and performance. However, knowledge about equine strongyles remains limited due to our inability to identify most species non-invasively using traditional morphological techniques. We developed a new internal transcribed spacer 2 (ITS2) DNA metabarcoding 'nemabiome' assay to characterise mixed strongyle infections in horses and assessed its performance by applying it to pools of infective larvae from fecal samples from an experimental herd in Kentucky, USA and two feral horse populations from Sable Island and Alberta, Canada. In addition to reporting the detection of 33 different species with high confidence, we illustrate the assay's repeatability by comparing results generated from aliquots from the same fecal samples and from individual horses sampled repeatedly over multiple days or months. We also validate the quantitative potential of the assay by demonstrating that the proportion of amplicon reads assigned to different species scales linearly with the number of larvae present. This new tool significantly improves equine strongyle diagnostics, presenting opportunities for research on species-specific anthelmintic resistance and the causes and consequences of variation in mixed infections., (Copyright © 2020 Australian Society for Parasitology. All rights reserved.)

Changes in primary productivity have the potential to substantially alter food webs, with positive outcomes for some species and negative outcomes for others. Understanding the environmental context and species traits that give rise to these divergent outcomes is a major challenge to the generality of both theoretical and applied ecology. In aquatic systems, nutrient-mediated eutrophication has led to major declines in species diversity, motivating us to seek terrestrial analogues using a large-mammal system across 598 000 km 2 of the Canadian boreal forest. These forests are undergoing some of the most rapid rates of land-use change on Earth and are home to declining caribou ( Rangifer tarandus caribou ) populations. Using satellite-derived estimates of primary productivity, coupled with estimates of moose ( Alces alces ) and wolf ( Canis lupus ) abundance, we used path analyses to discriminate among hypotheses explaining how habitat alteration can affect caribou population growth. Hypotheses included food limitation, resource dominance by moose over caribou, and apparent competition with predators shared between moose and caribou. Results support apparent competition and yield estimates of wolf densities (1.8 individuals 1000 km -2 ) above which caribou populations decline. Our multi-trophic analysis provides insight into the cascading effects of habitat alteration from forest cutting that destabilize terrestrial predator-prey dynamics. Finally, the path analysis highlights why conservation actions directed at the proximate cause of caribou decline have been more successful in the near term than those directed further along the trophic chain.

Studies of microbiome variation in wildlife often emphasize host physiology and diet as proximate selective pressures acting on host-associated microbiota. In contrast, microbial dispersal and ecological drift are more rarely considered. Using amplicon sequencing, we characterized the bacterial microbiome of adult female (n = 86) Sable Island horses (Nova Scotia, Canada) as part of a detailed individual-based study of this feral population. Using data on sampling date, horse location, age, parental status, and local habitat variables, we contrasted the ability of spatiotemporal, life history, and environmental factors to explain microbiome diversity among Sable Island horses. We extended inferences made from these analyses with both phylogeny-informed and phylogeny-independent null modelling approaches to identify deviations from stochastic expectations. Phylogeny-informed diversity measures were correlated with spatial and local habitat variables, but null modelling results suggested that heterogeneity in ecological drift, rather than differential selective pressures acting on the microbiome, was responsible for these correlations. Conversely, phylogeny-independent diversity measures were best explained by host spatial and social structure, suggesting that taxonomic composition of the microbiome was shaped most strongly by bacterial dispersal. Parental status was important but correlated with measures of β-dispersion rather than β-diversity (mares without foals had lower alpha diversity and more variable microbiomes than mares with foals). Our results suggest that between host microbiome variation within the Sable Island horse population is driven more strongly by bacterial dispersal and ecological drift than by differential selective pressures. These results emphasize the need to consider alternative ecological processes in the study of microbiomes., (© 2020 John Wiley & Sons Ltd.)

The adult sex ratio (ASR) is important within ecology due to its predicted effects on behaviour, demography and evolution, but research examining the causes and consequences of ASR bias have lagged behind the studies of sex ratios at earlier life stages. Although ungulate ASR is relatively well-studied, exceptions to the usual female-biased ASR challenge our understanding of the underlying drivers of biased ASR and provide an opportunity to better understand its consequences. Some feral ungulate populations, including multiple horse populations, exhibit unusually male-biased ASR. For example, research suggests that the feral horse Equus ferus caballus population on Sable Island, Nova Scotia, Canada may exhibit a male-biased ASR. Such exceptions to the rule provide a valuable opportunity to reveal the contributions of environmental context and trait differences to ASR bias. We aimed to test for bias in Sable Island horse ASR, identify the demographic drivers of bias, and explore its demographic and social consequences. To do this, we used life history, movement and group membership information for hundreds of horses followed through a long-term individual-based study between 2007 and 2018. Sable Island horse ASR is male biased and this skew has increased over time, reaching 62% male in 2018. Our life table response experiment suggested that ASR skew was driven predominantly by male-biased adult survival. Further analyses pointed to sex-biased survival being driven by reduced female survival post-reproduction. Male-biased ASR was associated with reduced harem sizes, an increase in the number of social groups on the island, and reduced reproduction in young females. Our results support the idea that male-biased ASR in feral ungulate populations may be caused by a combination of high population density and high reproductive output. We suggest that female-biased mortality may be caused by females continuing to reproduce at high density, and thus being more susceptible to resource shortages. Thus, our results highlight the strong context dependence of ASR. Furthermore, our work indicates the potential for ASR to substantially alter a population's social organisation. Such changes in social structure could have knock-on consequences for demography by altering the formation/stability of social relationships, or competition for matings., (© 2020 British Ecological Society.)

Polymorphisms within the prion protein gene (Prnp) are an intrinsic factor that can modulate chronic wasting disease (CWD) pathogenesis in cervids. Although wild European reindeer (Rangifer tarandus tarandus) were infected with CWD, as yet there have been no reports of the disease in North American caribou (R. tarandus spp.). Previous Prnp genotyping studies on approximately 200 caribou revealed single nucleotide polymorphisms (SNPs) at codons 2 (V/M), 129 (G/S), 138 (S/N), 146 (N/n) and 169 (V/M). The impact of these polymorphisms on CWD transmission is mostly unknown, except for codon 138. Reindeer carrying at least one allele encoding for asparagine (138NN or 138SN) are less susceptible to clinical CWD upon infection by natural routes, with the majority of prions limited to extraneural tissues. We sequenced the Prnp coding region of two caribou subspecies (n = 986) from British Columbia, Saskatchewan, Yukon, Nunavut and the Northwest Territories, to identify SNPs and their frequencies. Genotype frequencies at codon 138 differed significantly between barren-ground (R. t. groenlandicus) and woodland (R. t. caribou) caribou when we excluded the Chinchaga herd (p < .05). We also found new variants at codons 153 (Y/F) and 242 (P/L). Our findings show that the 138N allele is rare among caribou in areas with higher risk of contact with CWD-infected species. As both subspecies are classified as Threatened and play significant roles in North American Indigenous culture, history, food security and the economy, determining frequencies of Prnp genotypes associated with susceptibility to CWD is important for future wildlife management measures., (© 2020 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

A significant challenge of conservation biology is to preserve species in places where their critical habitat also attracts significant economic interest. The problem is compounded when species distributions occur across large spatial extents. Threatened boreal caribou (Rangifer tarandus caribou) epitomize this problem: their critical habitat encompasses a vast expanse of forest that also supplies much of Canada's merchantable timber. Boreal caribou were protected under the Canada Species at Risk Act in 2003. We investigated putative drivers of reduced disturbance for caribou habitat since then. Where the cumulative logging footprint slowed within caribou habitat, this has resulted neither from decreases in annual allowable cut of timber nor the creation or expansion of protected areas. Rather, it has fluctuated with the American economy relative to that of Canada. For each $0.05 US lost over the $CAD, 129 km2 of caribou habitat was not disturbed by logging in a given year. Recent population declines have been occurring even though logging typically remained at <70% of allowed levels. Our study raises concerns about how caribou are functionally being conserved under the current application of existing legislation. In this globalized world, the economy of foreign nations is increasingly likely to govern national conservation objectives., Competing Interests: The authors have declared that no competing interests exist.

Aim: The 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)., Location: Our 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., Methods: We 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., Results: Wolves 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 Conclusions: These 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., Competing Interests: None declared., (© 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Ecological and social factors underpinning the inequality of male mating success in animal societies can be related to sex ratio, sexual conflict between breeders, effects of nonbreeders, resource dispersion, climatic conditions, and the various sequential stages of mating competition that constitute the sexual selection process. Here, we conducted an individual-based study to investigate how local resource availability and demography interact with annual climate conditions to determine the degree of male mating inequality, and thus opportunity for sexual selection across two sequential reproductive episodes (harem and subsequent mate acquisition) in a naturally regulated (feral) horse population in Sable Island National Park Preserve, Canada. Using a 5-year, spatially explicit, mark-resight dataset and hierarchical mixed-effects linear modeling, we evaluated the influence of adult sex ratio (ASR) on mating success and then tested for effects of freshwater availability, density, unpaired male abundance, and precipitation during each breeding season. Unpaired male abundance, freshwater availability, and ASR differed in their effects on male mating success according to year and selection episode. Opportunity for sexual selection in males associated with harem acquisition increased with ASR, and unpaired male abundance further explained weather-related interannual variation after accounting for ASR. In contrast, once a harem was secured, ASR had little effect on male mating inequality in regard to acquiring additional females, while interannual variation in mating inequality increased with decreasing freshwater availability. Our findings show that local demography, resource availability, and weather effect opportunity for sexual selection in males differently depending on selection episode, and can attenuate or accentuate effects of ASR., Competing Interests: The authors declare that they have no conflict of interest.

Variability in host resistance or tolerance to parasites is nearly ubiquitous, and is of key significance in understanding the evolutionary processes shaping host-parasite interactions. While ample research has been conducted on the genetics of parasite burden in livestock, relatively little has been done in free-living populations. Here, we investigate the sources of (co)variation in strongyle nematode faecal egg count (FEC) and body condition in Sable Island horses, a feral population in which parasite burden has previously been shown to negatively correlate with body condition. We used the quantitative genetic "animal model" to understand the sources of (co)variation in these traits, and tested for impacts of an important spatial gradient in habitat quality on the parameter estimates. Although FEC is significantly heritable ( h 2  = 0.43 ± 0.11), there was no evidence for significant additive genetic variation in body condition ( h 2  = 0.04 ± 0.07), and therefore there was also no significant genetic covariance between the two traits. The negative phenotypic covariance between these traits therefore does not derive principally from additive genetic effects. We also found that both FEC and body condition increase from east to west across the island, which indicates that the longitudinal environmental gradient is not responsible for the negative phenotypic association observed between these traits. There was also little evidence to suggest that quantitative genetic parameters were biased when an individual's location along the island's environmental gradient was not incorporated into the analysis. This research provides new and important insights into the genetic basis and adaptive potential of parasite resistance in free-living animals, and highlights the importance of environmental heterogeneity in modulating host-parasite interactions in wild vertebrate systems.

Future changes in climate are widely anticipated to increase fire frequency, particularly in boreal forests where extreme warming is expected to occur. Feedbacks between vegetation and fire may modify the direct effects of warming on fire activity and shape ecological responses to changing fire frequency. We investigate these interactions using extensive field data from the Boreal Shield of Saskatchewan, Canada, a region where >40% of the forest has burned in the past 30 years. We use geospatial and field data to assess the resistance and resilience of eight common vegetation states to frequent fire by quantifying the occurrence of short-interval fires and their effect on recovery to a similar vegetation state. These empirical relationships are combined with data from published literature to parameterize a spatially explicit, state-and-transition simulation model of fire and forest succession. We use this model to ask if and how: (a) feedbacks between vegetation and wildfire may modify fire activity on the landscape, and (b) more frequent fire may affect landscape forest composition and age structure. Both field and GIS data suggest the probability of fire is low in the initial decades after fire, supporting the hypothesis that fuel accumulation may exert a negative feedback on fire frequency. Field observations of pre- and postfire composition indicate that switches in forest state are more likely in conifer stands that burn at a young age, supporting the hypothesis that resilience is lower in immature stands. Stands dominated by deciduous trees or jack pine were generally resilient to fire, while mixed conifer and well-drained spruce forests were less resilient. However, simulation modeling suggests increased fire activity may result in large changes in forest age structure and composition, despite the feedbacks between vegetation-fire likely to occur with increased fire activity., (© 2018 John Wiley & Sons Ltd.)

Isolation by distance (IBD) is a natural pattern not readily incorporated into theoretical models nor traditional metrics for differentiating populations, although clinal genetic differentiation can be characteristic of many wildlife species. Landscape features can also drive population structure additive to baseline IBD resulting in differentiation through isolation-by-resistance (IBR). We assessed the population genetic structure of boreal caribou across western Canada using nonspatial (STRUCTURE) and spatial (MEMGENE) clustering methods and investigated the relative contribution of IBD and IBR on genetic variation of 1,221 boreal caribou multilocus genotypes across western Canada. We further introduced a novel approach to compare the partitioning of individuals into management units (MU) and assessed levels of genetic connectivity under different MU scenarios. STRUCTURE delineated five genetic clusters while MEMGENE identified finer-scale differentiation across the study area. IBD was significant and did not differ for males and females both across and among detected genetic clusters. MEMGENE landscape analysis further quantified the proportion of genetic variation contributed by IBD and IBR patterns, allowing for the relative importance of spatial drivers, including roads, water bodies, and wildfires, to be assessed and incorporated into the characterization of population structure for the delineation of MUs. Local population units, as currently delineated in the boreal caribou recovery strategy, do not capture the genetic variation and connectivity of the ecotype across the study area. Here, we provide the tools to assess fine-scale spatial patterns of genetic variation, partition drivers of genetic variation, and evaluate the best management options for maintaining genetic connectivity. Our approach is highly relevant to vagile wildlife species that are of management and conservation concern and demonstrate varying degrees of IBD and IBR with clinal spatial genetic structure that challenges the delineation of discrete population boundaries.

Costs associated with reproduction are widely known to play a role in the evolution of reproductive tactics with consequences to population and eco-evolutionary dynamics. Evaluating these costs as they pertain to species in the wild remains an important goal of evolutionary ecology. Individual heterogeneity, including differences in individual quality (i.e., among-individual differences in traits associated with survival and reproduction) or state, and variation in environmental and social conditions can modulate the costs of reproduction; however, few studies have considered effects of these factors simultaneously. Taking advantage of a detailed, long-term dataset for a population of feral horses (Sable Island, Nova Scotia, Canada), we address the question of how intrinsic (quality, age), environmental (winter severity, location), and social conditions (group size, composition, sex ratio, density) influence the costs of reproduction on subsequent reproduction. Individual quality was measured using a multivariate analysis on a combination of four static and dynamic traits expected to depict heterogeneity in individual performance. Female quality and age interacted with reproductive status of the previous year to determine current reproductive effort, while no effect of social or environmental covariates was found. High-quality females showed higher probabilities of giving birth and weaning their foal regardless of their reproductive status the previous year, while those of lower quality showed lower probabilities of producing foals in successive years. Middle-aged (prime) females had the highest probability of giving birth when they had not reproduced the year before, but no such relationship with age was found among females that had reproduced the previous year, indicating that prime-aged females bear higher costs of reproduction. We show that individual quality and age were key factors modulating the costs of reproduction in a capital breeder but that environmental or social conditions were not, highlighting the importance of considering multiple factors when studying costs of reproduction.

The polygyny threshold (PT) is a critical transition point in the sexual selection process for many organisms in natural populations, characterizing when females choose to mate with an already mated male over an unmated one to improve fitness. Understanding its causes and consequences is therefore of high interest. While both theoretical and empirical work suggest that the degree of polygyny within a species is plastic and a function of male inequality, the functional relationship between underlying availability of resources occupied by breeding males under variable climatic conditions and the dynamics of PTs across space and time has received less attention. Here, we use a standardized measure of male mating inequality as the culmination of female mate choices to analyse how spatially dynamic PTs in a naturally regulated feral horse (Equus ferus caballus) population emerge along a geographic gradient in a known, limiting resource (freshwater) each year from variable climatic conditions. Polygyny threshold distance from permanent freshwater increased with increasing precipitation during the breeding season of each year, suggesting a relationship between annual resource availability and female mate choice. The mechanism by which climatic conditions underpin the spatial dynamics of PTs was likely through precipitation providing ephemeral freshwater sources across the study area that effectively weakened the gradient in availability of permanent freshwater, thereby providing mating males that occupied home ranges far from permanent water with access to this limiting resource and enabling them to attract and retain females. Increased precipitation also coincided with a decreased proportion of males in the population that experienced sexual selection pressure attributed to female mate choice in relation to the acquisition and/or defence of freshwater sources. Climatic conditions caused spatial shifts in PTs annually along the geographic gradient in resource availability. Our findings reveal that such environmental gradients may either buffer or amplify impacts of climatic variation on selection pressure operating in natural populations, and emphasize the importance of integrating spatially explicit PTs with atmospheric fluctuations when predicting the effect of climatic change on selection processes within populations that occupy environmental gradients., (© 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.)

The feral horses of Sable Island are a geographically isolated population located ∼160 km off the east coast of Nova Scotia, Canada. Because these horses have no contact with domestic animals, have minimal contact with people, and have never received antimicrobials, they offer a unique opportunity to study the dissemination of antimicrobial resistance in unmanaged populations. As part of an ongoing multidisciplinary and individual-based monitoring program, we collected feces from 508 geolocalized horses (92% of the total population) between July and September 2014. We selectively cultured Escherichia coli on MacConkey and CHROMagar ESBL media. Antimicrobial susceptibilities were determined, and organisms resistant to β-lactam antimicrobials were screened for β-lactamase genes by PCR. Escherichia coli was recovered from 146 (28.7%) individuals, and the majority of isolates (97%) were susceptible to all drugs tested. Resistance to tetracycline was most common, including organisms isolated from 4 (2.7%) of the colonized horses. A single isolate resistant to ampicillin, ceftriaxone, and ceftiofur was identified, which possessed the CTX-M-1 gene. Our findings demonstrate that although antimicrobial resistance is not common in this remote population, clinically relevant resistance genes are present.

Sea-to-land nutrient transfers can connect marine food webs to those on land, creating a dependence on marine webs by opportunistic species. We show how nitrogen, imported by gray seals, Halichoerus grypus, and traced through stable isotope (δ 15 N) measurements in marram grass, Ammophila breviligulata, significantly alters foraging behavior of a free-roaming megaherbivore (feral horses, Equus ferus caballus) on Sable Island, Canada. Values of δ 15 N correlated with protein content of marram and strongly related to pupping-seal densities, and positively influenced selective foraging by horses. The latter was density dependent, consistent with optimal foraging theory. We present the first demonstration of how sea-to-land nutrient transfers can affect the behavioral process of resource selection (resource use relative to availability) of terrestrial consumers. We hypothesize that persistence of horses on Sable Island is being facilitated by N subsidies. Our results have relevance to advancing theory on trophic dynamics in island biogeography and metaecosystem ecology., (© 2016 by the Ecological Society of America.)

In wild and domestic animals, gastrointestinal parasites can have significant impacts on host development, condition, health, reproduction and longevity. Improving our understanding of the causes and consequences of individual-level variation in parasite load is therefore of prime interest. Here we investigated the relationship between strongyle fecal egg count (FEC) and body condition in a unique, naturalized population of horses that has never been exposed to anthelmintic drugs (Sable Island, Nova Scotia, Canada). We first quantified variation in FEC and condition for 447 individuals according to intrinsic (sex, age, reproductive status, social status) and extrinsic (group size, location, local density) variables. We then quantified the repeatability of measurements obtained over a field season and tested for covariance between FEC and condition. FECs were high relative to other horse populations (mean eggs per gram ± SD = 1543·28 ± 209·94). FECs generally decreased with age, were higher in lactating vs non-lactating females, and unexpectedly lower in males in some part of the island. FECs and condition were both spatially structured, with patterns depending on age, sex and reproductive status. FECs and condition were both repeatable. Most notably, FECs and condition were negatively correlated, especially in adult females.

Individual-based study of natural populations allows for accurate and precise estimation of fitness components and the extent to which they might vary with ecological conditions. By tracking the fates of all 701 horses known to have lived on Sable Island, Canada, from 2009 to 2013 (where there is no predation, human interference, or interspecific competition for food), we present a detailed analysis of structured population dynamics with focus on interacting effects of intraspecific competition and weather on reproduction and survival. Annual survival of adult females (0.866 ± 0.107 [[Formula: see text] ± SE]) was lower than that of 3-year-olds (0.955 ± 0.051), although annual fecundity (producing a foal in a year that was observed during our census) was higher in adults (0.616 ± 0.023) compared to 3-year-olds (0.402 ± 0.054). Milder winters and lower densities during gestation increased fecundity. Density negatively impacted survival for all age and sex categories; however, highest adult female survival was observed during high-density years coupled with a harsh winter, the result expected if pregnancy loss during winter or loss of foals in spring improved survival. Three-year-old females, which reproduced at lower rates, experienced higher survival than adults. Our results contrast with a previous study of feral horses that suggested recently feral ungulates might be artificially selected to reproduce even when costs to survival are high. In part, this may be because of the comparably long history of feralization (250 years; at least 25 generations) for Sable Island horses.

Theory on density-dependent habitat selection predicts that as population density of a species increases, use of higher quality (primary) habitat by individuals declines while use of lower quality (secondary) habitat rises. Habitat partitioning is often considered the primary mechanism for coexistence between similar species, but how this process evolves with changes in population density remains to be empirically tested for free-ranging ungulates. We used resource-selection functions to quantify density effects on landscape-scale habitat selection of two sympatric species of ungulates [moose (Alces alces) and elk (Cervus canadensis manitobensis)] in Riding Mountain National Park, Manitoba, Canada (2000-2011). The density of elk was actively reduced from 1.2 to 0.4 elk km(-2) through increased hunting effort during the period of study, while moose density decreased without additional human influence from 1.6-0.7 moose km(-2). Patterns of habitat selection during winter by both species changed in accordance to expectations from density-dependent habitat-selection theory. At low intraspecific density, moose and elk did not partition habitat, as both species selected strongly for mixed forest (primary habitat providing both food and cover), but did so in different areas segregated across an elevational gradient. As intraspecific density increased, selection for primary habitat by both species decreased, while selection for secondary, lower quality habitat such as agricultural fields (for elk) and built-up areas (for moose) increased. We show that habitat-selection strategies during winter for moose and elk, and subsequent effects on habitat partitioning, depend heavily on the position in state space (density) of both species.

Density is a fundamental driver of many ecological processes including habitat selection. Theory on density-dependent habitat selection predicts that animals should be distributed relative to profitability of habitat, resulting in reduced specialization in selection (i.e. generalization) as density increases and competition intensifies. Despite mounting empirical support for density-dependent habitat selection using isodars to describe coarse-grained (interhabitat) animal movements, we know little of how density affects fine-grained resource selection of animals within habitats [e.g. using resource selection functions (RSFs)]. Using isodars and RSFs, we tested whether density simultaneously modified habitat selection and within-habitat resource selection in a rapidly growing population of feral horses (Equus ferus caballus Linnaeus; Sable Island, Nova Scotia, Canada; 42% increase in population size from 2008 to 2012). Among three heterogeneous habitat zones on Sable Island describing population clusters distributed along a west-east resource gradient (west-central-east), isodars revealed that horses used available habitat in a density-dependent manner. Intercepts and slopes of isodars demonstrated a pattern of habitat selection that first favoured the west, which generalized to include central and east habitats with increasing population size consistent with our understanding of habitat quality on Sable Island. Resource selection functions revealed that horses selected for vegetation associations similarly at two scales of extent (total island and within-habitat zone). When densities were locally low, horses were able to select for sites of the most productive forage (grasslands) relative to those of poorer quality. However, as local carrying capacity was approached, selection for the best of available forage types weakened while selection for lower-quality vegetation increased (and eventually exceeded that of grasslands). Isodars can effectively describe coarse-grained habitat selection in large mammals. Our study also shows that the main predictions of density-dependent habitat selection are highly relevant to our interpretation of RSFs in space and time. At low but not necessarily high population size, density will be a leading indicator of habitat quality. Fitness maximization from specialist vs. generalist strategies of habitat and resource selection may well be apparent at multiple spatial extents and grains of resolution., (© 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.)

Movement away from an area or social group in response to increasing density (density-dependent dispersal) is known for most species; why it evolves is fundamental to our understanding of ecology and evolution. However, we have yet to fully appreciate how individuals of varying conditions (e.g., age and sex) might differently consider effects of density (quorum) when deciding to disperse or not, and scale dependence in their sense of quorum. We tracked movements of all individuals of a naturalized population of feral horses (Equus ferus caballus; Sable Island National Park Reserve, Nova Scotia, Canada) during a period of rapid population growth (N increased from 375 to 484 horses from 2008 to 2010). Permanent dispersal from breeding groups (bands) was positively density dependent for all age and sex categories with respect to local density (horses/km(2), bounded by the 99th percentile of individual movements [8000 m]), but was negatively and positively density dependent for males and females, respectively, in relation to group (band) size. Dispersal was generally female biased, with the exception of foals which moved with their mothers (no sex effect), and for yearlings and subadults when band sizes were smaller than average, in which case males dispersed at higher rates than females. Dispersal distance was positively related to local density. We conclude that dispersal rate can be both positively and negatively density dependent for feral horses, contingent on the state of individuals and the scale at which quorum with respect to choosing to disperse or not is assessed. Scale effects and interactions of density-dependent and sex- and age-biased dispersal may have both ecological and evolutionary consequences through effects on resource and mate competition.

For animals living in natural or semi-natural settings, empirical data on how sociality changes in response to increasing population density are few, especially with respect to true conspecific density and not group size. However, insight into this line of research may be far-reaching--from understanding density dependence in sexual selection to improving models of disease transmission. Using elk (Cervus elaphus Linnaeus) held in enclosures, we conducted sex-stratified experiments to test how the frequency of dyadic pairings (interaction rate) and their quality (duration) responded to manipulations in exposure to density. Using proximity-logging radio collars we recorded when and for how long individuals shared a space within 1.4 m of each other. As predicted, males increased their interaction rate as density increased. Female interaction rates, however, increased initially as density increased but soon declined to become indistinguishable from rates at low density. Females interacted for longer periods at medium densities, whereas male interaction length clearly decreased as density increased. We highlight a sexually dichotomous, density-dependent response in sociality that has yet to be reported. In addition to furthering our understanding of sociobiology (e.g., implications of time constraints presented by density on dyadic interactions), our results have implications for managing communicable disease in gregarious species of livestock and wildlife.

Fine-scale spatial variation in genetic relatedness and inbreeding occur across continuous distributions of several populations of vertebrates; however, the basis of observed variation is often left untested. Here we test the hypothesis that prior observations of spatial patterns in genetics for an island population of feral horses (Sable Island, Canada) were the result of spatial variation in population dynamics, itself based in spatial heterogeneity in underlying habitat quality. In order to assess how genetic and population structuring related to habitat, we used hierarchical cluster analysis of water sources and an indicator analysis of the availability of important forage species to identify a longitudinal gradient in habitat quality along the length of Sable Island. We quantify a west-east gradient in access to fresh water and availability of two important food species to horses: sandwort, Honckenya peploides, and beach pea, Lathyrus japonicas. Accordingly, the population clusters into three groups that occupy different island segments (west, central, and east) that vary markedly in their local dynamics. Density, body condition, and survival and reproduction of adult females were highest in the west, followed by central and east areas. These results mirror a previous analysis of genetics, which showed that inbreeding levels are highest in the west (with outbreeding in the east), and that there are significant differences in fixation indices among groups of horses along the length of Sable Island. Our results suggest that inbreeding depression is not an important limiting factor to the horse population. We conclude that where habitat gradients exist, we can anticipate fine-scale heterogeneity in population dynamics and hence genetics.

1. Describing distribution and abundance is requisite to exploring interactions between organisms and their environment. Recently, the resource selection function (RSF) has emerged to replace many of the statistical procedures used to quantify resource selection by animals. 2. A RSF is defined by characteristics measured on resource units such that its value for a unit is proportional to the probability of that unit being used by an organism. It is solved using a variety of techniques, particularly the binomial generalized linear model. 3. Observing dynamics in a RSF - obtaining substantially different functions at different times or places for the same species - alerts us to the varying ecological processes that underlie resource selection. 4. We believe that there is a need for us to reacquaint ourselves with ecological theory when interpreting RSF models. We outline a suite of factors likely to govern ecologically based variation in a RSF. In particular, we draw attention to competition and density-dependent habitat selection, the role of predation, longitudinal changes in resource availability and functional responses in resource use. 5. How best to incorporate governing factors in a RSF is currently in a state of development; however, we see promise in the inclusion of random as well as fixed effects in resource selection models, and matched case-control logistic regression. 6. Investigating the basis of ecological dynamics in a RSF will allow us to develop more robust models when applied to forecasting the spatial distribution of animals. It may also further our understanding of the relative importance of ecological interactions on the distribution and abundance of species.

We examined the relationship between survival of roe deer (Capreolus capreolus) fawns at Trois Fontaines, Champagne-Ardennes, France, and factors related to bed-site selection (predator avoidance and thermoregulation) and maternal food resources (forage availability in the maternal home range). Previous studies have demonstrated that at small scales, the young of large herbivores select bed sites independently from their mothers, although this selection takes place within the limits of their mother's home range. Fawn survival was influenced largely by the availability of good bed sites within the maternal home range, not by the fawn's selection of bed sites; however, selection for thermal cover when selecting bed sites positively influenced survival of young fawns. Typical features of a good home range included close proximity to habitat edges, which is related to forage accessibility for roe deer. The availability of bed sites changed as fawns aged, probably due to an increased mobility of the fawn or a different use of the home range by the mother; sites offering high concealment and thermal protection became less available in favor of areas with higher forage accessibility. Despite the minor influence of bed-site selection on survival, roe deer fawns strongly selected their bed sites according to several environmental factors linked to predator avoidance and thermoregulation. Fawns selected for sites providing concealment, light penetration, and avoided signs of wild boar (Sus scrofa) activity. Avoidance of sites with high light penetration by young fawns positively affected their survival, confirming a negative effect on thermoregulation due to reduced thermal cover. Selection for light penetration by older fawns was less clear. We discuss these results in the context of cross-generational effects in habitat selection across multiple scales, and the potential influence of the 'ghost of predation past'.

We used long-term data on movements, survival, and reproduction of female red deer (Cervus elaphus Linnaeus) of the Isle of Rum, Scotland (1970-2001), to explain variation in life history (age at maturity) from a hind's access to habitat resources and exposure to local density, and cross-generational (maternal) effects on observed relationships. We described each hind's use of resources relative to availability in the study area from an individual-based resource selection function (RSF); we defined local density as the total number of hinds aged > or = 1 year within the subpopulation cluster to which an individual belonged. The likelihood of a hind producing her first calf in the period from birth to the end of the summer in which she turned age 3 was positively related to relative use of Agrostis/Festuca grasslands and other low-elevation communities, and inversely related to a hind's mean annual local density. However, when we considered both a daughter's RSF and exposure to local density and her mother's RSF and exposure to local density, maternal data alone most parsimoniously explained variation in age at maturity of daughters. Mothers were able to lower age at maturity in their daughters in two, non-mutually exclusive ways. First, birth mass of daughters was inversely related to age at maturity, and mothers that used relatively less uplands (Calluna-dominated heath and heather moorland) and occupied areas of lower density produced larger offspring. Second, mothers could establish a home range that enabled daughters to mature in areas with access to high quality Agrostis/Festuca grasslands at low density. Lifetime reproductive success was inversely associated with a hind's age at maturity via extension of the reproductive life span. Longevity did not change in association with age at maturity. Patterns in how animals use available habitat resources may depend on that of previous generations, especially at larger scales of resource selection.

The relationship between individual performance and nonrandom use of habitat is fundamental to ecology; however, empirical tests of this relationship remain limited, especially for higher orders of selection like that of the home range. We quantified the association between lifetime reproductive success (LRS) and variables describing lifetime home ranges during the period of maternal care (spring to autumn) for 77 female roe deer (Capreolus capreolus) at Trois-Fontaines, Champagne-Ardenne, France (1976-2000). We maintained population growth rate (adjusted to account for removals of non-focal animals) near rmax, which enabled us to define the fitness-habitat relationship in the absence of density effects. Using a negative binomial model, we showed that a roe deer's incorporation into its home range of habitat components important to food, cover, and edge (meadows, thickets, and increased density of road allowances) was significantly related to LRS. Further, LRS decreased with increasing age of naturally reclaimed meadows at the time of a deer's birth, which may have reflected a cohort effect related to, but not entirely explained by, a decline in quality of meadows through time. Predictive capacity of the selected model, estimated as the median correlation (rs) between predicted and observed LRS among deer of cross-validation samples, was 0.55. The strength of this relationship suggests that processes like selection of the site of a home range during dispersal may play a more important role in determining fitness of individuals than previously thought. Individual fitness of highly sedentary income breeders with high reproductive output such as roe deer should be more dependent on home range quality during the period of maternal care compared to capital breeders with low reproductive output. Identification of the most important habitat attributes to survival and reproduction at low density (low levels of intraspecific competition) may prove useful for defining habitat value ("intrinsic habitat value").

Individuals are predicted to maximize lifetime reproductive success (LRS) through selective use of resources; however, a wide range of ecological and social processes may prevent individuals from always using the highest-quality resources available. Resource selection functions (RSFs) estimate the relative amount of time an individual spends using a resource as a function of the proportional availability of that resource. We quantified the association between LRS and coefficients of individual-based RSFs describing lifetime resource selection for 267 female red deer (Cervus elaphus) of the Isle of Rum, Scotland, from 1970 to 2001. LRS was significantly related to first- and second-order effects of selection for Agrostis/Festuca grassland and proximity to the sea coast (quality of forage within Agrostis/Festuca grassland was highest nearest the coast (ratio of short:long grassland)). The benefits of selecting for quality in Agrostis/Festuca grassland, however, traded-off with increases in LRS gained by avoiding conspecific density. LRS was inversely associated with local density, which was highest along the coast, and reproductive benefits of selecting Agrostis/Festuca grassland diminished with increasing density. We discuss the relevance of these results to our understanding of the spatial distribution of red deer abundance, and potential applications of our approach to evolutionary and applied ecology.

Using resource selection functions, we examined habitat selection patterns of barren-ground grizzly bears (Ursus arctos) in the central Canadian Arctic among and within home ranges. There was no difference between the sexes with regard to habitat selection patterns at the home range level (Wilks' λ, approx. F 11,11 =1.27, P=0.37). Bear home ranges contain more esker habitat, tussock/hummock successional tundra, lichen veneer, birch seep, and tall shrub riparian areas relative to the proportional availability of habitats in the study area. We observed differences in habitat selection within home ranges among levels of sex/reproductive status (Wilks' λ, approx. F 20,412 =3.32, P<0.001) and by season (Wilks' λ, approx. F 30,605 =2.71, P<0.001). Eskers and tall shrub riparian zones were the habitats most preferred by bears throughout the year. Tussock/hummock successional tundra was also favored by males at varying times during the year and lichen veneers were favored in spring and autumn by most bears. Females with cubs tended to avoid the highest ranked habitat for males throughout the year. This pattern of habitat selection was not observed for females without accompanying young. Results of this study underline the importance of scale dependence in habitat selection. Failure to view habitat selection as a hierarchical process may result in a narrow and possibly misleading notion of habitat selection patterns.