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AIM: Population‐limiting factors represent the core of conservation biology. Because animal space use is affected by ecological constraints that can vary among populations, limiting factors might be revealed from intraspecific variation in home range size. We evaluated biogeographic variation in the home range size of woodland caribou (Rangifer tarandus caribou), a threatened species inhabiting the boreal forest, in relation to land cover, topography, snowcover and disturbance across the species’ range. LOCATION: Twenty‐five populations in Canada, spanning the contiguous boreal forest (an east–west extent of 4,400 km), including the southern fringe of the species’ range, adjacent to a broad region of extirpation. METHODS: We compiled the average annual home range size of adult female caribou (5–68 home ranges per population) and 18 putative predictor variables in each population range. We uncovered major gradients using principal components analysis and then evaluated models of home range size using multiple regression, with orthogonal variables representing vegetation, human disturbance and snowcover. RESULTS: Average home range size varied 28‐fold among populations (range: 312–8,838 km²). Home range area was most strongly and negatively correlated with anthropogenic disturbance in the population range (R² = 0.391), a variable in all seven top models (ΔAICc ≤ 5.99). Among populations, where human disturbance in the population range was low (≤10%), mean home range sizes consistently exceeded 1,400 km². Conversely, where human disturbance was high (>55%), especially at the species’ southern range margin, mean home range sizes did not exceed 1,500 km². MAIN CONCLUSIONS: In the boreal forest, female caribou may constrict their home ranges amid human‐caused disturbances. We speculate that smaller home ranges may lower the risk of encounter by predators, a key limiting factor. Among populations, smaller home ranges may serve as a signal of anthropogenic habitat loss.

Identifying limiting factors is fundamental to understanding and conserving mammals, yet it often requires long-term data for long-lived species. Numerical changes of migratory caribou ( Rangifer tarandus ), for example, may unfold over decades, but few studies have examined habitat use at similar timeframes. We analyzed multiple decades of habitat use by caribou in Newfoundland, Canada, coincident with their numeric growth ( r = 0.064 in 1980s, 1990s) and decline ( r = −0.099 in 2000s). We examined 2 scales: selection of land cover, based on radiotracking of 520 adult females, and diet, based on microhistological analysis of feces and age-specific tooth wear from jawbones of harvested animals. Caribou responded at both scales. In contrast to previous decades, females during the population decline used proportionally less open coniferous and closed coniferous forests, they used more shrublands (in fall and winter) and barrens, open habitats with greater vascular plant resources. Patterns of selection also changed from nonselection to avoidance of open coniferous forest and from avoidance to nonselection or preference of barrens. The proportion of dietary moss increased at the expense of deciduous shrubs, especially during spring and summer and of ericaceous shrubs, graminoids, and lichens during winter. Teeth of both sexes exhibited premature wear, likely indicative of abrasion from low-quality forages and cropping of foods near the ground. These patterns mirror other responses, including declines in calf weight, female body size, number of male antler points, herd affinities, and time spent on the summer grounds. We surmise that they reflect density-dependent forage limitation of this island population.

The recently diminished caribou (Rangifer tarandus) population in insular Newfoundland, Canada, has been severely limited by predation on newborn calves. These neonates are patchily distributed on the landscape; therefore, to adequately understand predator–prey interactions, the temporal and geographic extent of the distribution of caribou calves must be identified so that current areas with calves can be differentiated from areas without calves. We used telemetry locations of 309 caribou calves and 100 adult females from 4 herds, 2008– 2010, to estimate the spatiotemporal distribution of caribou calves during the time when they were most vulnerable to predation, to evaluate the predictability of the calf resource among years, and to assess the degree of aggregation during calving. Patterns of calf distribution were predictable in time and space from year to year, with an average distributional overlap of 68% between years. The dispersion of female caribou during calving varied among herds from highly aggregated (8% and 20% of herd range) to more dispersed (50–70% of herd range). Postcalving (up to 9 weeks) distributions also varied among herds; the 2 more-dispersed herds remained sedentary, whereas both highly aggregated herds migrated away from their calving grounds at the end of June. The most-aggregated herd remained so as it migrated from its calving ground, whereas the less-aggregated herd spread out and moved in a variety of predictable directions. Dispersion and movement patterns varied with forest cover; herds with less forest cover in their range were more aggregated and migratory than herds with more forest cover.

Understanding the relationship between abundance and distribution is central to ecology but may require broad-scale observations, especially for long-lived, mobile animals like caribou (Rangifer tarandus (L., 1758)). We tested the link between demography and spatial ecology of Newfoundland caribou, coincident with their numerical growth (1980s, 1990s) and decline (2000s). We analysed site fidelity, rate of movements, timing of migration, and population organization from telemetry observations of more than 600 adult females. Site fidelity was consistent across herds, intensifying near the onset of calving and peaking in late summer, a cycle that may reflect selection for postpartum security. Late-summer fidelity was stronger in the 1980s than 1990s, a trend that reversed itself during the 2000s. Weekly movements were lower in the 2000s, but with no clear differences between the 1980s and 1990s. Timing of migration changed: in the 2000s, spring migration of the Buchans herd occurred 3 weeks earlier and autumn migration 3 weeks later compared with the previous decade, the reversal of a 40-year trend. Herd affinities, revealed by fuzzy membership coefficients, diminished by the 2000s. These changes are consistent with the hypothesis of limitation by summer forage competition. Space use represents a useful gauge of numerical changes in caribou.

Global warming threatens to reduce population connectivity for terrestrial wildlife through significant and rapid changes to sea ice. Using genetic fingerprinting, we contrasted extant connectivity in island-dwelling Peary caribou in northern Canada with continental-migratory caribou. We next examined if sea-ice contractions in the last decades modulated population connectivity and explored the possible impact of future climate change on long-term connectivity among island caribou. We found a strong correlation between genetic and geodesic distances for both continental and Peary caribou, even after accounting for the possible effect of sea surface. Sea ice has thus been an effective corridor for Peary caribou, promoting inter-island connectivity and population mixing. Using a time series of remote sensing sea-ice data, we show that landscape resistance in the Canadian Arctic Archipelago has increased by approximately 15% since 1979 and may further increase by 20–77% by 2086 under a high-emission scenario (RCP8.5). Under the persistent increase in greenhouse gas concentrations, reduced connectivity may isolate island-dwelling caribou with potentially significant consequences for population viability.

Conservation strategies have a tendency to discount range peripheries, but recent evidence suggests that range edges may be important to species persistence by harboring genetic variants not found in core distributions. Wolverines in Canada are recognized as existing in two populations—an endangered eastern population and an extant western population thought to be largely panmictic. Studies from western North America identified strong patterns of female philopatry and increased genetic structure at the current southwestern periphery. Due to the paucity of data from the contemporary eastern periphery, it remains unclear if similar patterns exist at this range edge. Using neutral microsatellite and mitochondrial DNA markers from a broad geographic extent (>2,500 km), we found that wolverines at the eastern periphery displayed strong patterns of genetic distinctiveness from northwestern populations. While the microsatellite data suggest contemporary genetic structure exists, the haplotypic composition of the eastern periphery drastically differed from the core, indicating longstanding differences between regions. Further research is needed to determine if wolverines from the eastern periphery show evidence of interactions with the functionally extirpated eastern population, if functional markers display similar patterns of genetic diversity, and what relevance these may have in their evolutionary potential. Pronounced environmental fluctuations at range boundaries likely contribute to peripheral populations having genotypes with a greater capacity to respond to future selection pressures like climate change and may become a vital source of genetic diversity should core regions become replaced by edge habitats, and thus warrant separate conservation consideration.

Monitoring the distribution and movements of a species following reintroduction can aid resource managers in assessing release-site fidelity, rates of spread, initial project success, and feasibility of (or need for) future releases. We used radio-telemetry to monitor an entire founding population of 70 elk (Cervus elaphus) during 16 months following their reintroduction to eastern Ontario, Canada. At the end of the study, elk were widely scattered over a 27,000 km 2 area. Dispersal distances ranged from 2 to 142 km; 50% of animals moved >40 km from the release site. Dispersal distances differed by time periods and age but not sex. Calves dispersed significantly shorter distances than adults and many mature elk were isolated during the rut. In contrast to a random distribution model, movements had a strongly southwestern directional bias, perhaps owing to prevailing winds from the same direction. Mortality during the study period was 27%; the primary causes of known mortalities were emaciation, collision with automobiles, and illegal shooting. During the first 11/2 years, lack of releasesite fidelity and high dispersal coupled with animal-human conflicts and mortalities likely contributed to an initial lag in population growth. Resource managers planning animal reintroductions should consider using methodologies that enhance site fidelity following release.

Preferential spatial associations between related animals have been reported in several species, but whether these relationships extend to fine resolution is largely unknown. Using a novel approach that combined pedigrees and precise geographic locations, we tested the relationship between extremely fine-scale (

Logging has often been implicated in the decline of caribou (Rangifer tarandus), but its effects are incompletely understood. We used a distance-based approach to assess the effects of progressive clearcut logging on the summer (28 May to 15 Sep) range of caribou in Newfoundland, Canada. We compared distances of random locations and of caribou, from 9 years of radiotelemetry, to landcover types across 3 spatial scales: population range, individual ranges, and radiolocations. We tested for incremental avoidance of cutovers and mature softwood forests, the preferred type for caribou and forest harvesting, while controlling for the confounding effects of each. At the individual range, females selected for hardwood and softwood forests, bogs, and barrens, and they avoided open water. Patterns for males were similar, although they avoided bogs and barrens at both scales. The sexes differed in their response to forest harvesting. Females progressively avoided cutovers, both pre- and postharvest, likely...

Habitat loss and anthropogenic mortality are recognized as threats to populations of large carnivores worldwide, yet their relative importance to extinction risk has rarely been quantified. We used population viability analysis (PVA) to estimate extinction probability of an isolated population of black bears (Ursus americanus) on the Bruce Peninsula, Ontario, Canada under different management scenarios. We used random-effects analysis of variance to estimate components of variance in extinction risk explained by 4 management actions: 1) preventing habitat destruction, 2) reducing or eliminating incidental non-natural mortality, 3) reducing or eliminating harvest, and 4) reducing the fraction of reproducing females in the harvest. Habitat area reductions had the greatest effect on risk despite uncertainty in bear density. Incidental non-natural mortality had a greater effect than the rate or age and sex distribution of harvest. Quantifying the variation in outputs of PVA models associated with different management options is an improvement over qualitative comparisons of relative risk and enhances the applicability of PVA to management. This study highlights the importance of protecting habitats on adjacent private lands when reserves are too small to support populations of bears, and of protecting reproducing females from non-natural mortality—results that could aid managers of other large carnivores in focusing management efforts to ensure persistence of populations.

Climate can have direct and indirect effects on population dynamics via changes in resource competition or predation risk, but this influence may be modulated by density- or phase-dependent processes. We hypothesized that for ungulates, climatic conditions close to parturition have a greater influence on the predation risk of neonates during population declines, when females are already under nutritional stress triggered by food limitation. We examined the presence of phase-dependent climate-predator (PDCP) interactions on neonatal ungulate survival by comparing spatial and temporal fluctuations in climatic conditions, cause-specific mortality and per capita resource limitation. We determined cause-specific fates of 1384 caribou (Rangifer tarandus) from 10 herds in Newfoundland, spanning more than 30 years during periods of numerical increase and decline, while exposed to predation from black bears (Ursus americanus) and coyotes (Canis latrans). We conducted Cox proportional hazards analysis for competing risks, fit as a function of weather metrics, to assess pre- and post-partum climatic influences on survival on herds in population increase and decline phases. We used cumulative incidence functions to compare temporal changes in risk from predators. Our results support our main hypothesis; when caribou populations increased, weather conditions preceding calving were the main determinants of cause-specific mortality, but when populations declined, weather conditions during calving also influenced predator-driven mortality. Cause-specific analysis showed that weather conditions can differentially affect predation risk between black bears and coyotes with specific variables increasing the risk from one species and decreasing the risk from the other. For caribou, nutritional stress appears to increase predation risk on neonates, an interaction which is exacerbated by susceptibility to climatic events. These findings support the PDCP interactions framework, where maternal body condition influences susceptibility to climate-related events and, subsequently, risk from predation.

Recent literature has emphasized the central role of populations in biological thought and practice, yet a unified population concept remains elusive. I contend that a more mature framework for populations could be realized by dispensing with arbitrary population bounds which, in turn, will entail recognition that populations exist on multiple spatial scales and that populations are inherently vague. I illustrate this framework by decomposing the population structure of a hypothetical organism distribution using fuzzy classification at multiple scales. Hierarchy and vagueness represent the building blocks of a more inclusive population concept.

Variation in home-range size can be related to different factors at different spatial scales. This study exam - ined the patterns of home-range size and habitat selection of American marten (Martes americana) in southeastern Labrador, a region of extensive and pristine forests. Over 1.5 years, we monitored 28 radio-collared marten and com- pared the availability of habitat types with their use. Marten avoided areas with low productivity and low canopy cover (

Movement is a primary mechanism coupling animals to their environment, yet there exists little empirical analysis to test our theoretical knowledge of this basic process. We used correlated random walk (CRW) models and satellite telemetry to investigate long-distance movements of caribou, the most vagile, non-volant terrestrial vertebrate in the world. Individual paths of migratory and sedentary female caribou were quantified using measures of mean move length and angle, and net squared displacements at each successive move were compared to predictions from the models. Movements were modelled at two temporal scales. For paths recorded through one annual cycle, the CRW model overpredicted net displacement of caribou through time. For paths recorded over shorter intervals delineated by seasonal behavioural changes of caribou, there was excellent correspondence between model predictions and observations for most periods for both migratory and sedentary caribou. On the smallest temporal scale, a CRW model significantly overpredicted displacements of migratory caribou during 3 months following calving; this was also the case for sedentary caribou in late summer, and in late winter. In all cases of overprediction there was significant positive autocorrelation in turn direction, indicating that movements were more tortuous than expected. In one case of underprediction, significant negative autocorrelation of sequential turn direction was evident, indicating that migratory caribou moved in straightened paths during spring migration to calving grounds. Results are discussed in light of known migration patterns and possible limiting factors for caribou, and indicate the applicability of CRW models to animal movement at vast spatial and temporal scales, thus assisting in future development of more sophisticated models of population spread and redistribution for vertebrates.

Studies of site fidelity have been hampered by arbitrary designations of spatial scale and the lack of null models for comparison. We generated null expectations of fidelity at different scales from the distribution of radio-tracked animals in a population. We applied the models to space use of satellite-tracked caribou (Rangifer tarandus caribou), the most vagile nonvolant terrestrial animal, from populations representing sedentary and migratory ecotypes. We compared distances between consecutive-year locations of adult females to expectations based on the total range and seasonal range of each population. At the scale of the total range, sedentary and migratory caribou displayed remarkably similar philopatry, despite a 30-fold difference in size of their population ranges, from time of calving (late May) to breeding (late October). The most intense fidelity occurred during post-calving when, on average, sedentary and migratory females returned to as near as 6.7 km and 123 km, respectively, of locations occupied the previous year. At the scale of the seasonal range, the ecotypes differed. Sedentary caribou still displayed fidelity from calving to breeding; migratory caribou exhibited fidelity only during late autumn. For migratory, but not sedentary caribou, inter-year distances during winter were negatively correlated with age, implying that older females were more philopatric. We conclude that reproductive activities delimit the season of fidelity of female caribou of both ecotypes, and that scale-dependent ecotypic differences in fidelity may reflect different factors of population limitation. A spatially-explicit approach to site fidelity is essential for synthesizing patterns across studies.

We investigated the propensity for wild m uskoxen Ovibos moschatus (Zim m erm an, 1780) to exhibit right or left bias in foreleg use w hile foraging during winter. We found little evidence o f such lateralisation, either on the individual or population level. Only 3 o f 40 anim als exhibited significant right- or left-footedness, and the distribution across the population for use o f either lim b w as near 50%. Tim e-series analysis revealed that lateralisation o f paw use was sequentially dependent. M uskoxen tended to use the same paw for one ensuring bout, but were also inclined to switch sides over durations o f 4 bouts. The lack o f lateral bias, at least for this behaviour, contrasts with the general, em erging pattern for the M amm alia. D epartm ent o f Biology, U niversity o f Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada

Interglacial-glacial cycles of the Quaternary are widely recognized in shaping phylogeographic structure. Patterns from cold adapted species can be especially informative - in particular, uncovering additional glacial refugia, identifying likely recolonization patterns, and increasing our understanding of species’ responses to climate change. We investigated phylogenetic structure of the wolverine, a wide-ranging cold adapted carnivore, using a 318 bp of the mitochondrial DNA control region for 983 wolverines (n = 209 this study, n = 774 from GenBank) from across their full Holarctic distribution. Bayesian phylogenetic tree reconstruction and the distribution of observed pairwise haplotype differences (mismatch distribution) provided evidence of a single rapid population expansion across the wolverine’s Holarctic range. Even though molecular evidence corroborated a single refugium, significant subdivisions of population genetic structure (0.01< ΦST

We studied the winter resource selection of muskoxen Ovibos moschatus in the High Arctic using a nested hierarchy of spatial scales : 1) population range, 2) travel routes, 3) feeding sites (i.e. clusters of feeding craters), 4) feeding craters, and 5) diet (i.e. plant species). We found that, generally, patterns of selection remained consistent across all levels. At successively smaller scales, muskoxen selected for higher graminoid abundance and particularly for thinner, softer snow cover, although we did not reject the hypothesis of random travel route selection. Muskoxen uncovered forages from beneath the snow cover, by cratering, near the floristic and nival extremes of availability. Selection was consistently biased toward use of water sedge, Carex aquatilis. As scale changed, however, muskoxen showed reversals of preference for some other forage species. Diet was dominated by C. aquatilis and cotton sedge, Eriophorum angustifolium, species characteristic of lowland meadows. During spring melt, muskoxen moved to snow-free uplands to feed. Dietary quality, as revealed by fecal nitrogen, increased at this time. The consistency of the results across scales implied that these local levels of habitat selection occurred within one scaling domain.

The Mealy Mountain caribou population of southeastern Labrador is listed as threatened. Site fidelity - the philopatric tendency of an animal to remain in or return to the same site - has often been suspected in sedentary caribou like the Mealy Mountain, but rarely has been examined. Philopatric behaviours are important because fidelity sites may then receive priority protection from human disturbance. To describe and document site fidelity for the Mealy Mountain herd, satellite telemetry data from 12 collared adult females during three years was examined. The mean distance between locations in consecutive years of tracking the individual caribou was calculated and an annual profile of site fidelity generated. This profile illustrated that the lowest inter-year distances occurred during calving, when caribou returned to within 39 km (2005-06) and 11.5 km (2006-07) of the previous year's location, and during post-calving, when the mean distance was 7.7 km (2005-06). Spring snow depths were substantially greater in 2007 and appeared to weaken calving site fidelity. This spatial information may serve as a basis for detecting anthropogenic effects on woodland caribou.

Population density, one of the most fundamental demographic attributes, may vary systematically with spatial scale, but this scale-sensitivity is incompletely understood. We used a novel approach-based on fully censused and mapped distributions of eastern grey squirrel (Sciurus carolinensis) dreys, beaver (Castor canadensis) lodges, and moose (Alces alces)--to explore the scale-dependence of population density and its relationship to landscape features. We identified population units at several scales, both objectively, using cluster analysis, and arbitrarily, using artificial bounds centred on high-abundance sites. Densities declined with census area. For dreys, this relationship was stronger in objective versus arbitrary population units. Drey density was inconsistently related to patch area, a relationship that was positive for all patches but negative when non-occupied patches were excluded. Drey density was negatively related to the proportion of green-space and positively related to the density of buildings or roads, relationships that were accentuated at coarser scales. Mean drey densities were more sensitive to scale when calculated as organism-weighted versus area-weighted averages. Greater understanding of these scaling effects is required to facilitate comparisons of population density across studies.

I examined the relationships among snow cover (api), lichen abundance, and canopy composition on the range of the Aikens Lake population of woodland caribou (Rangifer tarandus caribou) in southeastern Manitoba. Percent cover of forage lichens (Cladina spp.) was positively correlated with maximum total thickness and with maximum vertical hardness of api. Mixed communities of trembling aspen (Populus tremuloides), spruce (Picea spp.), and balsam fir (Abies balsamea) showed the most favourable nival conditions for caribou but had low lichen abundance; those dominated by jack pine (Pinus banksiana) were the converse. The results suggest an energetic compromise for woodland caribou when foraging for terrestrial lichens. During winter, caribou exhibited significant selection for jack pine communities whereas mixed communities were avoided.

A comparison of indigenous and scientific forms of wildlife data gathering and conservation/management reveals similarities and differences. The two systems are needed to effectively manage wildlife in northern Canada, particularly migratory, trans-boundary species. The Beverly and Kaminuriak Caribou Management Board brought multi-jurisdictional caribou users and managers together to co-manage two large herds of caribou (Rangifer tarandus groenlan-dicus). The advisory Board's principal duties and responsibilities are communication and to maintain the two herds at population levels that will meet user needs. Goals, objectives, and principles are set out in a management plan. Board activities are structured in 15 action plans under major categories of communication, supply of caribou, use of caribou, and habitat. Board successes are attributed to use of the plan to guide actions; to the Chairmen and vice-Chairmen; to the quality of founding members and their continuity; to effective vehicles of communication such as a newspaper, radio, video, and community meetings; to a spirit of cooperation; and to high caribou numbers because of high productivity combined with poor accessibility. Problem areas include technical limitations, members' decreasing powers and increasing turnover, inadequate communication of Board objectives and activities within the communities, and accountability. Future challenges include the management of caribou shortages, obtaining better herd data, and the need for more intensive management as user populations grow.

Quantitative measures of social complexity derived from three different research endeavors are compared statistically for the same fifty societies. The scales are found to be correlated at a high level of significance; this suggests that the variables used are valid indicators of degree of social complexity and development.