Due to its neurotoxicity and tendency to bioaccumulate, Hg is a risk to both human and environmental health. Most Hg studies focus on aquatic systems due to their longer food chains and predatory fish. Yet opportunistic terrestrial predators such as wolves (Canis lupus) are less studied, despite the potential for high-Hg prey in their diets that could lead to high concentrations and subsequent health effects. Here, we studied the movement of Hg to wolves from their prey across two regions of the Northwest Territories, Canada between 2006 and 2024 by combining stomach content data with stable isotope analysis of more than 350 individuals. Although terrestrial prey such as caribou dominated the diet of wolves in both regions (> 55% of stomachs), a small number of wolves in both regions recently consumed aquatic prey (5%), and these aquatic prey had significantly higher Hg concentrations than terrestrial prey (p < 0.001). This led to higher Hg concentrations in wolves that had eaten aquatic prey relative to those eating semi-aquatic and terrestrial prey and is likely responsible for Hg trophic magnification factors that matched or exceeded those typically observed in aquatic systems. These findings highlight the transfer of Hg from aquatic to terrestrial food webs and the potential for health risks to terrestrial predators. Mercury concentrations in wolves remained well below expected animal health effect thresholds, and there was no evidence for an increase in concentrations in either region over the last decade, but the high concentrations in some prey species and trophic magnification in wolves illustrate the vulnerability of terrestrial predators to Hg exposure when their diets contain aquatic prey.

The Arctic wolf (Canis lupus arctos) is a predator of muskoxen (Ovibos moschatus), Arctic hares (Lepus arcticus), and endangered Peary caribou (Rangifer tarandus pearyi) in the Canadian High Arctic. Although Arctic wolves potentially affect the dynamics of muskoxen and Peary caribou populations, knowledge about their abundance, distribution, and predation patterns is limited. Inuit and Inuvialuit communities value these species for sociocultural and subsistence reasons, and community members are concerned about how interactions among these species and their environment may change in a warming, unpredictable Arctic. We conducted a study from 2014-2018 of wolves in the rolling tundra of central Ellesmere Island (Fosheim Peninsula) and eastern Axel Heiberg Island. This area supported relatively high densities of muskoxen and Arctic hares, and previously supported Peary caribou, although caribou were mostly absent in the area during our study. We deployed global positioning system (GPS) radio-collars on 10 adult wolves in 6 packs on Ellesmere and Axel Heiberg islands to describe wolf density and predation patterns. Wolves were neither nomadic nor migratory; they remained on territories year-round, with summer densities of 2.5-8.0 adult wolves/1,000 km2 and 3.7-10.4 wolves/1,000 km2 including pups. Based on a ground search of 312 of 868 location clusters over a 340-day period, wolves in a focal study pack killed approximately 0.12 muskoxen/day, equivalent to a predation rate of 5.5-17.0% of the estimated muskox population (older than 10 months old). This predation rate is likely sustainable given that calves and yearlings rather than reproductive adults comprised most documented kills, and that muskox populations can increase at rates up to 20%. The kill rate for this pack also implied a biomass intake deficit of 0.82-1.63 kg/wolf/day that could have been offset by each wolf consuming 115-228 Arctic hares annually. The decline of Peary caribou in the study area precluded any assessment of wolf predation influences on their population, but annual telemetry data confirming the year-round presence of a wolf-ungulate-hare system with relatively high wolf densities suggests that apparent competition could present a challenge to Peary caribou recovery efforts.

We investigated a multi-year mass mortality event in muskoxen (Ovibos moschatus) on Ellesmere and Axel Heiberg Islands, Nunavut, Canada and linked the deaths with the "Arctic clone" of the bacterium Erysipelothrix rhusiopathiae (Er), making this the third reported independent mass mortality event in muskoxen associated with this bacterial strain. Between 2021 and 2024, we collected and analyzed samples from 139 unique muskox carcass sites using gross and microscopic pathology, bacterial culture, and molecular methods. Er Arctic clone was found in association with > 70% of sampled carcasses. Our results underscore the geographic expanse over which this unique clonal lineage of Er has now spread, its apparently high virulence in muskoxen, and its ongoing importance as a consideration in conservation and monitoring efforts related to this species.

Evidence for relationships between people, dogs, and wolves can be found across much of the world. Methods for studying archaeological canid remains, particularly where sex or age is concerned, are limited. Reliable estimations of age at death could provide insights into the long and complex relationships people had with canids, including how they vary geographically, temporally, and by species. This study uses X-ray micro-computed tomography (mu-CT) to examine mandibular 1st molar root cross-sections for age estimation. Cementum is a reliable indicator of age in canids because it accumulates incrementally and resists remodelling. The proportion of cross-sectional area comprised of cementum (%C) is assessed for its correlation with age in 13 cementum aged modern wolves and 11 known-aged modern dogs. This study demonstrates that %C, visualized using mu-CT techniques, is an effective tool for determining the age at death for dogs and wolves (combined as a single group), with an error margin of 1.65 years. Taxon-specific %C regressions offer higher resolution, with error margins of 1.68 years for dogs and 1.45 years for wolves; however, sample sizes are small. The method is then applied to archaeological canids from the Junction site (DkPi-2) in Alberta, Canada. These techniques indicate that a few dogs and many wolves of all ages were present at the site, including juvenile/young adult, prime-age adults, and senescent individuals. Explaining this pattern is challenging, but it likely involved a combination of natural deaths, culling, predation, and some wolf-human conflict.

Age-related patterns in cranial suture and synchondrosis obliteration in 371 known-age North American grey wolves (Canis lupus) are examined to assess their utility in estimating the age of archaeological and paleontological wolf crania. Differences in age-related obliteration patterns between these wolves and 576 known-age domestic dogs (Canis familiaris) also are explored. Domestication has likely altered the growth and development of dog crania in relation to that of wolves, but these processes remain poorly understood. Wolf total suture obliteration score and age were positively correlated, indicating that the level of suture obliteration can be used to track age to some extent. Wolf sex and dietary patterns had no meaningful effects on this correlation. Mesocephalic or dolichocephalic dogs generally begin exhibiting more extensive suture obliteration than wolves during early adulthood, at about 2-4 years of age. This pattern of more extensive obliteration persists throughout the lifespan, with dogs tending to experience more obliteration in the observed sutures and synchondroses. Several interrelated factors may contribute to this pattern, all outcomes of domestication, including differences in physical strains in the cranium, alteration of development and ageing, and the emergence of diverse head shapes that relate in part to suture closure timing.

People, wolves, and dogs have interacted in various ways for millennia, but most aspects of these relationships remain poorly understood. Understanding canid age at death can provide insights into these relationships and how they vary geographically, temporally, and by species. Existing methods for ageing canids are limited, highlighting a need for a method that is pragmatic, reliable, and stems from a population of known age individuals. This study uses 368 known-age modern wolves from Alberta, Yellowstone National Park, and the Northwest Territories to examine how tooth wear rates correlate with age. Wolves are employed in this study because they have relatively restricted body sizes and diets, especially in comparison to modern dogs. Our results show a moderately strong correlation (r<-0.63 for all measurements) between tooth crown height and age when examined across the total wolf sample. Correlations improve when populations are examined individually, with the NWT wolves yielding a correlation of -0.83 for the mandibular M1-2 dimension. Body size, sexual dimorphism, and diet likely influence the variance seen in crown heights and their relationship to age, though the differences are statistically insignificant in many of our samples. Using tooth crown heights to age archaeological dogs will be more difficult due to the increased variation in body size, diet, and living conditions. Crown height measurements will be most informative about age at death when correlations are established for specific, local populations of wolves and dogs. Ultimately, the use of multiple ageing methods, including crown height measurements, cementum ageing, and perhaps cranial suture closure and obliteration, will produce the most reliable results for ancient canid remains.

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.

Canine circoviruses (CanineCV) have a worldwide distribution in dogs and are occasionally detected in wild carnivorans, indicating their ability for cross-species transmission. However, fox circovirus, a lineage of CanineCV, has been identified exclusively in wild canids. We analyzed spleen samples from 159 grey wolves from the Northwest Territories, Canada, to investigate the molecular epidemiology of CanineCV and formulate hypotheses about virus ecology and evolution. Overall, 72 out of 159 (45.3%) animals tested positive. Virus prevalence was similar between males and females, adults and juveniles, and across the investigated years and locations. CanineCV infection was not associated with a poor body condition. While the percentage of co-infections with canine parvoviruses, investigated in a previous study, was high (63/72, 87.5%), the rate of parvovirus infection in CanineCV-negative animals was significantly lower (42/87, 48.3%, χ2 = 27.03, p < 0.001), and CanineCV infection was associated with a 7.5- and 2.4-fold increase in the risk of acquiring canine parvovirus 2 or canine bufavirus infections, respectively (odds ratios: 3.5-16.9 and 1.3-5.8). Although common risk factors cannot be ruled out, this suggests that CanineCV may facilitate parvoviral super-infections. Sequencing revealed high CanineCV genetic diversity, further exacerbated by recombination. Of the 69 sequenced strains, 87.5% were fox circoviruses, five were related to a fox circovirus-like recombinant strain, and one belonged to a distant lineage. In the phylogenetic analysis, the virus sequences were distributed according to sampling locations, with some viruses being geographically restricted. Different clades of viruses were identified in the same areas and over multiple years (2007-2019), indicating the co-existence of multiple endemic lineages in the investigated area. Phylogenetic analysis of all available complete fox circovirus genomes (32 from foxes and 15 from wolves from North America and Europe) demonstrated four lineages, each including sequences from this study. Within each lineage, strains segregated geographically and not by host. This implies that, although multiple lineages co-exist, viruses do not frequently move between locations. Finally, viruses from Europe and North America were mixed, indicating that the origin of the four lineages might predate the segregation of European and American wolf and fox populations. Given the high prevalence and diversity of fox circoviruses in wolves, these animals should be considered reservoir hosts for these viruses. Although we cannot exclude a lower susceptibility of dogs, the lack of fox circovirus in dogs could be due to environmental circumstances that prevented its spread to dogs. Given the high diversity and wild host specificity, we presume a long-lasting association between fox circovirus and canine hosts and hypothesize a higher likelihood of transmission from dogs to wild animals than vice versa. Further studies should investigate other sympatric wild species and additional locations to explore the possible existence of additional maintenance hosts and the reasons behind the marked difference in cross-species transmission dynamics among CanineCV lineages.

Abstract The ability to track animals with Global Positioning System (GPS) collars opened an enormous potential for studying animal movements and behaviour in their natural environment. One such endeavour is to identify clusters of GPS locations as a way to estimate predator kill rate. Clapp et al. (2021) developed an R package (GPSeqClus) to assess a location dataset based on user‐defined parameters to identify clusters and their characteristics. These characteristics can then help to distinguish resting‐site clusters from kill sites of their large (>50 kg) prey. We identified location clusters of an adult male wolf Canis lupus on Ellesmere Island, Nunavut, Canada in July 2009 and tracked him until he died in April 2010. Identifying location clusters was challenging because the collar only obtained two GPS locations per day (12 h apart). In July 2010, we searched 30 of 52 location‐clusters we identified as kill/scavenge sites and found 17 of them as such, given they had muskox Ovibos moschatus or caribou Rangifer tarandus pearyi remains nearby. We also documented five wolf rendezvous sites, two den sites, and the wolf's death site to total 60 location‐clusters in all. We used a two‐step process in testing the R Package GPSeqClus (hereafter GPSeqClus): (1) compare the number of clusters our method discerned with the number identified by the new algorithm, and (2) compare the number of biologically significant clusters (e.g. den sites, kill/feeding sites) we found with the number the new algorithm located. We made these tests with GPSeqClus by varying the search radius, number of days at a site, and minimum number of locations required for a cluster. GPSeqClus compared well to our technique, with the best sub‐algorithm among the 25 we tested only missing three of our identified clusters and yielding six additional clusters. GPSeqClus identified 16 of the 17 confirmed sites of remains, all wolf home sites, and the wolf's carcass site. Identifying clusters using a 500‐m search radius, a 1.5‐day window, and a minimum of two GPS locations per cluster was suitable for a coarse GPS acquisition rate of two locations per day when prey are large, such as muskox or caribou. Given that GPSeqClus performed well with our coarse location dataset, we expect it will also perform even better with a collar acquiring more than two locations per day. Having a field‐tested utility such as GPSeqClus will enhance carnivore predation studies elsewhere.

Genetic diversity is theorized to decrease in populations closer to a species' range edge, where habitat may be suboptimal. Generalist species capable of long-range dispersal may maintain sufficient gene flow to counteract this, though the presence of significant barriers to dispersal (e.g., large water bodies, human-dominated landscapes) may still lead to, and exacerbate, the edge effect. We used microsatellite data for 2421 gray wolves (Canis lupus) from 24 subpopulations (groups) to model how allelic richness and expected heterozygosity varied with mainland-island position and two measures of range edge (latitude and distance from range center) across >7.3 million km(2) of northern North America. We expected low genetic diversity both at high latitudes, due to harsh environmental conditions, and on islands, but no change in diversity with distance to the range center due to the species' exceptional dispersal ability and favorable conditions in far eastern and western habitats. We found that allelic richness and expected heterozygosity of island groups were measurably less than that of mainland groups, and that these differences increased with the island's distance to the species' range center in the study area. Our results demonstrate how multiple axes of geographic isolation (distance from range center and island habitation) can act synergistically to erode the genetic diversity of wide-ranging terrestrial vertebrate populations despite the counteracting influence of long-range dispersal ability. These findings emphasize how geographic isolation is a potential threat to the genetic diversity and viability of terrestrial vertebrate populations even among species capable of long-range dispersal.

Several viruses can infect wild carnivores but their impact on wildlife health is poorly understood. We investigated the presence, diversity and distribution of various DNA viruses in 303 wolves inhabiting a vast area of the Northwest Territories, Canada, over a period of 13 years. We found evidence for the presence of canine bufavirus (CBuV, 42.6%), canine parvovirus 2 (CPV-2, 34.0%), canine bocavirus 2 (CBoV-2, 5.0%), cachavirus (CachaV-1, 2.6%), canine adenovirus 1 (CAdV-1, 1%) and minute virus of canines (MVC, 0.3%). To our knowledge, this is the first detection of CBoV-2, MVC and CachV-1 in wild animals. We also demonstrate that CBuV and CachaV-1 were already circulating among wild animals at least 11 and 10 years, respectively, before their discoveries. Although CBuV prevalence was higher, CPV-2 was the most prevalent virus among juveniles, while CBuV infection was associated with poor nutrition conditions. Even if its prevalence was low, CachaV-1 had the highest multiple infection rate (87.5%). CadV-1 and MVC sequences were highly identical to reference strains, but we observed a high diversity among the other viruses and detected three new variants. One CPV-2 variant and one CBuV variant were endemic since the beginning of the 2000s in the entire investigated region, whereas one CBuV variant and two CBoV-2 variants were found in a more restricted area over multiple years and CachaV-1 was found only in one region. Two CPV-2 variants and one CachaV-1 variant were observed only once, indicating sporadic introductions or limited circulation. Different patterns of endemicity might indicate that viruses were introduced in the wolf population at different timepoints and that mixing between wolf packs may not be constant. Different epidemiological behaviors depend on viral factors like infectivity, transmission routes, pathogenicity and tissue-tropism, and on host factors like proximity to densely populated areas, carnivory and pack density and mixing.

Due to concerns about the appearance of portions of liver from a harvested adult, male barren-ground caribou ( Rangifer tarandus groenlandicus), samples were submitted for diagnostic investigation. The gross and histologic findings were consistent with severe hepatic fibrosis and mineralization. Concentrations of vitamin E in the liver were also deficient. Disease investigations in wildlife of detectable abnormalities such as this provide important information for understanding the role of disease as populations change, as well as for safety of human food sources.

We used the Qamanirjuaq, Bathurst, and George River barren-ground caribou sine cycles to project numbers (Nt), calculate subpopulation annual growth rates (λt) and calculate logistic carrying capacity (Kt). Maximum annual growth rate was 1.196 and maximum annual rate of decline was 0.836 for the harvested Qamanirjuaq subpopulation sine cycle. However, the maximum annual subpopulation growth rates for both the harvested Bathurst and George River subpopulation sine cycles were greater than the biologically possible maximum intrinsic rate of increase during the eruption phase. Subpopulation numbers for Qamanirjuaq, Bathurst and George River barren-ground caribou subpopulations all closely tracked carrying capacity for one complete cycle with lag times between Nt and Kt ranging from < 1-year to approximately 5-years. The short lag times observed indicates that Qamanirjuaq, Bathurst and George River barren-ground caribou subpopulations closely track their range condition. Range condition drives barren-ground caribou subpopulation cycles, but range condition also cycles; presumably because annual barren-ground caribou grazing rates are proportional to barren-ground caribou numbers and eventually exceed range annual growth rates. Immigration from adjacent subpopulations plays a role in the initiation and acceleration of the eruption period in some subpopulations, but not all of them. Numerical synchrony and asynchrony with adjacent subpopulation cycles can affect the timing of the eruption phase through mediation of immigration. Once subpopulation range has recovered, the rapid recovery of subpopulation numbers suggest that subpopulations are not restricted by other factors. The regularity and symmetry of both the increase and decline phases of these cycles suggests that the barren-ground caribou cycle is both stable and resilient. Continuation of barren-ground caribou cycles at historical levels is likely if habitat conservation measures are adopted so that annual migration patterns are not disrupted, summer and winter range remain undisturbed and common-sense harvest management policies are adopted when caribou are at low numbers.

The presence of many pathogens varies in a predictable manner with latitude, with infections decreasing from the equator towards the poles. We investigated the geographic trends of pathogens infecting a widely distributed carnivore: the gray wolf ( Canis lupus ). Specifically, we investigated which variables best explain and predict geographic trends in seroprevalence across North American wolf populations and the implications of the underlying mechanisms. We compiled a large serological dataset of nearly 2000 wolves from 17 study areas, spanning 80° longitude and 50° latitude. Generalized linear mixed models were constructed to predict the probability of seropositivity of four important pathogens: canine adenovirus, herpesvirus, parvovirus, and distemper virus—and two parasites: Neospora caninum and Toxoplasma gondii . Canine adenovirus and herpesvirus were the most widely distributed pathogens, whereas N. caninum was relatively uncommon. Canine parvovirus and distemper had high annual variation, with western populations experiencing more frequent outbreaks than eastern populations. Seroprevalence of all infections increased as wolves aged, and denser wolf populations had a greater risk of exposure. Probability of exposure was positively correlated with human density, suggesting that dogs and synanthropic animals may be important pathogen reservoirs. Pathogen exposure did not appear to follow a latitudinal gradient, with the exception of N. caninum . Instead, clustered study areas were more similar: wolves from the Great Lakes region had lower odds of exposure to the viruses, but higher odds of exposure to N. caninum and T. gondii ; the opposite was true for wolves from the central Rocky Mountains. Overall, mechanistic predictors were more informative of seroprevalence trends than latitude and longitude. Individual host characteristics as well as inherent features of ecosystems determined pathogen exposure risk on a large scale. This work emphasizes the importance of biogeographic wildlife surveillance, and we expound upon avenues of future research of cross-species transmission, spillover, and spatial variation in pathogen infection.

Muskoxen (Ovibos moschatus) are an integral component of Arctic biodiversity. Given low genetic diversity, their ability to respond to future and rapid Arctic change is unknown, although paleontological history demonstrates adaptability within limits. We discuss status and limitations of current monitoring, and summarize circumpolar status and recent variations, delineating all 55 endemic or translocated populations. Acknowledging uncertainties, global abundance is ca 170 000 muskoxen. Not all populations are thriving. Six populations are in decline, and as recently as the turn of the century, one of these was the largest population in the world, equaling ca 41% of today's total abundance. Climate, diseases, and anthropogenic changes are likely the principal drivers of muskox population change and result in multiple stressors that vary temporally and spatially. Impacts to muskoxen are precipitated by habitat loss/degradation, altered vegetation and species associations, pollution, and harvest. Which elements are relevant for a specific population will vary, as will their cumulative interactions. Our summaries highlight the importance of harmonizing existing data, intensifying long-term monitoring efforts including demographics and health assessments, standardizing and implementing monitoring protocols, and increasing stakeholder engagement/contributions.

Large carnivores can be found in different scenarios of cohabitation with humans. Behavioral adaptations to minimize risk from humans are expected to be exacerbated where large carnivores are most vulnerable, such as at breeding sites. Using wolves as a model species, along with data from 26 study areas across the species' worldwide range, we performed a meta-analysis to assess the role of humans in breeding site selection by a large carnivore. Some of the patterns previously observed at the local scale become extrapolatable to the entire species range provided that important sources of variation are taken into account. Generally, wolves minimised the risk of exposure at breeding sites by avoiding human-made structures, selecting shelter from vegetation and avoiding agricultural lands. Our results suggest a scaled hierarchical habitat selection process across selection orders by which wolves compensate higher exposure risk to humans within their territories via a stronger selection at breeding sites. Dissimilar patterns between continents suggest that adaptations to cope with human-associated risks are modulated by the history of coexistence and persecution. Although many large carnivores persisting in human-dominated landscapes do not require large-scale habitat preservation, habitat selection at levels below occupancy and territory should be regarded in management and conservation strategies aiming to preserve these species in such contexts. In this case, we recommend providing shelter from human interference at least in small portions of land in order to fulfill the requirements of the species to locate their breeding sites.

Gray wolves (Canis lupus L., 1758) are mobile opportunistic predators that can be infected by a wide range of parasites, with many acquired via predator–prey relationships. Historically, many of these parasites were identified only to genus or family, but genetic tools now enable identification of parasite fauna to species and beyond. We examined 191 intestines from wolves harvested for other purposes from regions in the Northwest Territories, British Columbia, Saskatchewan, and Manitoba. Adult helminths were collected from intestinal contents for morphological and molecular identification, and for a subset of wolves, fecal samples were also analyzed to detect helminth eggs and protozoan (oo)cysts. Using both detection methods, we found that 83% of 191 intestines contained one or more parasite species, including cestodes (Taenia spp., Echinococcus spp., and Diphyllobothrium sp.), nematodes (Uncinaria stenocephala Railliet, 1884, Trichuris spp., Physaloptera spp., and Toxascaris leonina (von Linstow, 1902)), a trematode (Alaria sp.), and protozoa (Sarcocystis spp., Giardia sp., and Cryptosporidium spp.). Molecular characterization identified one species of Diphyllobothrium (Diphyllobothrium latum (L., 1758) Cobbold, 1858), three species of Taenia (Taenia krabbei Moniez, 1879, Taenia hydatigena Pallas, 1766, and Taenia multiceps Leske, 1786), and two Giardia duodenalis (Davaine) Deschiens, 1921 assemblages (B and C). These results demonstrate the diverse diet of wolves and illustrate the possibility of parasite spillover among wildlife, domestic animals, and people.

The severity of recent declines of barren-ground caribou (Rangifer tarandus groenlandicus) across the central Canadian Arctic has led to harvest restrictions and concerns about population recovery. Wolves (Canis lupus) are the main predator of barren-ground caribou; however, the extent that wolves influence the decline and recovery of caribou herds is unknown. Such uncertainty confounds management responses (e.g., reducing harvest, predator control). We investigated wolf-caribou dynamics on the summer range of barren-ground caribou in the Northwest Territories and Nunavut, Canada (i.e., Bathurst caribou herd). Our primary objective was to test for a numerical response of wolves to changes in the abundance and spatial distribution of caribou. Caribou experienced a > 90% decline in abundance over the study period (1996-2014). Using long-term data sets (1996-2012), we developed regression models to investigate relationships between abundance indices of wolves and range-use patterns of caribou. We monitored the movements of adult female wolves fitted with global positioning system (GPS) collars representing individual packs throughout the 2013 and 2014 denning periods. We also investigated pup recruitment, an index of population decline, at a time of low caribou abundance. Finally, we developed a series of stochastic population models to understand how pup recruitment influenced wolf densities on the Bathurst range over the period of caribou decline. As caribou abundance decreased, the late-summer distribution of the Bathurst herd contracted toward the calving ground. These movements correlated with low rates of wolf pup recruitment and high den abandonment, suggesting a regulatory mechanism whereby wolf reproductive success was limited by the low availability of caribou within the denning areas. Furthermore, these data suggested a numerical response, where wolf densities decreased as caribou numbers declined. In 2014, wolf density was estimated at < 4 wolves/1,000 km(2). Our results suggest that these wolves exhibited a relatively strong numerical response to a single, declining prey base. Given the continued decline in the Bathurst caribou herd, the tundra wolf population on the Bathurst range has likely declined below our 2014 estimate. (C) 2016 The Wildlife Society.

Immunoglobulin A deficiency (IgAD) is the most common primary immunodeficiency in both humans and selected breeds of domestic dogs. In both species, IgAD is associated with recurrent infections and immune mediated diseases. Previous results imply that IgAD is also common in the wild ancestor of domestic dogs, the gray wolf. Here, we report that serum IgA concentrations are significantly different in Scandinavian and Canadian wolves (p =3.252e-15) with an increased prevalence for IgAD in Scandinavian wolves (60%), which is as high as those found in high-risk dog breeds. (C) 2014 Elsevier Ltd. All rights reserved.

Wolves (Canis lupus) that den on the tundra of the central Arctic prey primarily on migratory barren-ground caribou (Rangifer tarandus groenlandicus). Prey densities in the vicinity of den sites are low, however, for a period each summer when caribou migrate to their calving and post-calving ranges. Eskers provide substrate where wolves can excavate den sites, but these landforms make up only a small proportion of the tundra landscape. We investigated the factors that influenced den site selection for wolves on the summer range of the Bathurst caribou herd, Northwest Territories, Canada. We used a long-term data set (1996–2012) of wolf den locations to develop a series of resource selection function (RSF) models representative of broad land-cover types, esker density, and annual variation in seasonal prey availability. We compared a temporal sequence of RSF models to investigate whether wolves altered selection patterns in response to a 90 % decline in caribou abundance (1996–2012). Eskers were selected denning habitat; the distribution of eskers may be limiting when wolf density is high. Covariates representing the seasonal distribution of caribou from early (5–18 July) and late (19 July–22 August) summer were the best predictors of den occurrence; these areas represented reliable availability of caribou over the greatest portion of the denning period. As the caribou herd declined, the seasonal summer ranges contracted northward towards the calving ground. Wolves did not exhibit a similar response. As such, the period of spatial separation between breeding wolves at den sites and the main distribution of caribou increased when herd abundance was low. The lack of a behavioural response is consistent with wolf–prey dynamics observed in other studies that suggest wolves strive to maintain consistent territories even following large decreases in resource availability. Such behaviours reduce fitness and have implications for pup survival and population growth.