Northwest Territories

Mid-Continental Canadian forests , Muskwa-Slave Lake forests, Northern Canadian Shield taiga, Northern Cordillera forest , Northwest Territories taiga, Arctic coastal tundra, Brooks-British Range tundra, High Arctic tundra, Low Arctic tundra, Middle Arctic tundra, Ogilvie-MacKenzie alpine tundra

Naturally occurring stable isotope ratios and fatty acids are two types of chemical biomarkers frequently used to quantitatively estimate consumer diets. Stable isotope values in animal tissues and diets have been evaluated using Bayesian mixing models to provide dietary estimates of consumers in both terrestrial and marine ecosystems. Fatty acids have primarily been used to examine diets of marine species. Using muscle and adipose tissue, we combined the two biomarkers in a Bayesian mixing model to generate quantitative diet estimates for gray wolves (Canis lupus, n = 78) in the southern Northwest Territories, Canada. Simulation experiments showed that the combined dataset led to more accurate and precise diet estimates than stable isotopes alone. Overall, Bison (Bison bison athabascae) dominated the winter diet (63–96%) of wolves. In one region where Bison were not readily available, wolf diet was more variable, with substantial contributions from boreal caribou (Rangifer tarandus caribou), moose (Alces alces), snowshoe hare (Lepus americanus), and beaver (Castor canadensis). Surprisingly, fish also comprised 5–26% of wolf diet in this region. Wolves likely scavenged on scraps left behind by commercial ice fishing operations on Great Slave Lake. Our investigation underlines the power of combining these two major analytical tools to investigate diet in an elusive and opportunistic predator.

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.

As part of a larger study, wolf stomachs were collected from entire wolf carcasses collected by local harvesters from Sachs Harbour (71°59’N 125°15’W) on Banks Island from 1992-2001, and from Ulukhaktok, formerly Holman (70°45’N 117°42’W) on Northwest Victoria Island from 1998-2001. Wolf scats were collected opportunistically during field research trips conducted on Banks Island from 1993-2001 and on Northwest Victoria Island from 1998-1999. A total of 129 stomachs and 38 scats from Banks Island, and 30 stomachs and two scats from Northwest Victoria Island were analyzed macro and microscopically for hair, feather, and bone fragments of prey items. Prey items were identified as closely as possible to species. Seventeen stomachs were empty. Remains of muskoxen (Ovibos moschatus) predominated being found in 90% of 115 and 88% of 27 stomachs from Banks Island and Northwest Victoria Island, respectively, and 87% of 38 and 100% of two scats from Banks Island and Northwest Victoria Island, respectively. Peary caribou (Rangifer tarandus pearyi), collared lemming (Dicrostonyx torquatus), Arctic hare ( Lepus arcticus), Arctic fox (Alopex lagopus), snow goose ( Chen caerulescens), ptarmigan ( Lagopus spp.), and plant material were also found in stomachs and scats; however, only Peary caribou and collared lemming occurred in ≥5% of either stomachs or scats

Events during the denning period (parturition to first autumn) often determine the reproductive success of wolves (Canis lupus). Consequently, there is concern about the potential adverse effects of human-caused disturbance at wolf den and rendezvous sites (homesites), but relatively little information on this subject is available. We conducted standardized experimental disturbance treatments at 12 unique wolf homesites in the Northwest Territories, Canada, during summers 2002 and 2003. The treatment consisted of an intruder approaching a homesite once per day for 3 consecutive days and recording behavioral responses, response distance, and response intensity of wolves. We counted pups and estimated their ages prior to the initial treatment at each site. Adult wolves moved pups at 3 of 6 treated homesites in each year. The amount and type of known human activity within a pack’s home range did not influence whether adults moved pups in response to the treatment. The response intensity of wolves to the treatment was inversely related to the amount of human activity near a homesite. There was no relationship between the distance at which wolves responded to the intruder and the amount or type of human activity. There was a positive relationship between increasing age of pups and their relocation in response to the treatment. Reproductive success was not influenced by the treatment or by the amount and type of human activity. Treated sites were used by wolves the following year in the same proportion as untreated sites. It appears that pups are most vulnerable early in the year when less mobile; therefore, managers should consider age of pups before human activity at or near wolf homesites occurs.

This study characterizes population genetic structure among grey wolves (Canis lupus) in northwestern Canada, and discusses potential physical and biological determinants of this structure. Four hundred and ninety-one grey wolves, from nine regions in the Yukon, Northwest Territories and British Columbia, were genotyped using nine microsatellite loci. Results indicate that wolf gene flow is reduced significantly across the Mackenzie River, most likely due to the north–south migration patterns of the Barren-Ground Caribou herds that flank it. Furthermore, although Banks and Victoria Island wolves are genetically similar, they are distinct from mainland wolf populations across the Amundsen Gulf. However, low-level island–mainland wolf migration may occur in conjunction with the movements of the Dolphin-Union caribou herd. Whereas previous authors have examined isolation-by-distance in wolves, this study is the first to demonstrate correlations between genetic structure of wolf populations and the presence of topographical barriers between them. Perhaps most interesting is the possibility that these barriers reflect prey specialization by wolves in different regions.

We collected information on the movement patterns of wolves (Canis lupus) captured within a 30,000-km2 area in the Northwest Territories and western Nunavut. Currently, diamond mining and road construction are occurring in the area used by these migratory wolves for denning. During summers of 1997 and 1998, 23 wolves in 19 different packs were captured and fitted with collar-mounted satellite transmitters. Areas used by these wolves varied seasonally and seemed to correspond to movements of migratory caribou (Rangifer tarandus). Annual home-range sizes (95% minimum convex polygon), averaged 63,058 km2 ± 12,836 SE for males and 44,936 ± 7,564 km2 for females. Wolves began to restrict movements around a den site on the tundra by late April. They did not depart from their summer ranges until late October, after which they followed caribou to their wintering grounds. Straight-line distances from the most distant location on the winter range to the den site averaged 508 ± 26 km during 1997–1998 and 265 ± 15 km in 1998–1999 (P < 0.01). Home range in summer averaged 2,022 ± 659 km2 for males and 1,130 ± 251 km2 for females. No difference was detected between sexes or years. All but 2 of 15 wolves returned to <25 km of a previous den, and 2 wolves returned to the same den site. We believe that human activities that disturb or displace denning wolves, or that alter the distribution or timing of caribou movements, will have negative affects on reproductive success of wolves

Of 205 female wolves (Canis lupus) shot by Inuit hunters between 1987 and 1989 in the Keewatin District, Northwest Territories, Canada, 97 were parous, and 16 gravid females carried 73 identifiable fetuses. Fetuses grew at a mean rate of 5.17 g/day between day 32 post coitus and parturition. During the same period, fetuses increased in length at a mean rate of 0.204 cm/day. No significant sexual dimorphism in body mass or other morphological features was found at this stage of development. Cranio-caudal length ranged from 3 mm shortly after implantation to approximately 185 mm at parturition. All correlations of morphological parameters with cranio-caudal length were significant, and with the exception of humerus length and contour length, all parameters increased faster than cranio-caudal length. The results are discussed in relation to reproductive and developmental strategies in canids.

Twenty-two skeletal, visceral, and adipose parameters were compared in 425 wolves collected from the central Arctic between 1987 and 1989. Fifteen parameters differed significantly by sex. Males were usually larger than females; however, the degree of sexual dimorphism varied with structure. Male skeletal parameters ranged between 3 and 6% greater than those of females, and significant differences were largely associated with the anterior body region and the limbs. Male body mass was 18% and male visceral parameters ranged between 12 and 24% heavier than those of females. Patterns of adipose deposition were also significantly different. Sternum and inguinal fat depths and total external and mesentery fat indices were significantly greater in males (5–44%), while rump fat depth was significantly greater in females (1%). These results support the conclusion that sexual dimorphism in wolves has evolved primarily as a foraging strategy, owing to division of labour between the sexes, and males are more highly specialized for capturing and killing large ungulate prey, while females are more specialized for a nurtural role.

Winter feeding habits of wolves (Canis lupus) from the Keewatin District, Northwest Territories, were examined through analysis of stomach contents. Carcasses were collected from Inuit hunters at four different locations (Eskimo Point, Rankin Inlet, Baker Lake, and Repulse Bay) during the winters of 1987 to 1989. A total of 237 stomachs were analysed. Observations indicate that caribou (Rangifer tarandus) constituted the most frequent item (92.7%), while moose (Alces alces) remains were less frequent (5.3%). Other items present in low frequencies were muskoxen (Ovibos moschatus), wolf, birds, grasses, and indigestible material (rocks, garbage, and woody shrubs).

Geographic differences were noted and appeared to be related to latitudinal ranges of prey species. Whereas caribou comprised an almost exclusive food source for wolves in central and northern portions of the study area, moose constituted a secondary prey species utilized by wolves to the south.

On both a weight and volume basis, caribou constituted the principle (94.6% and 94.8%, respectively) food item present in the stomach contents.

Temporal changes were noted in the frequency with which caribou were preyed upon by wolves.

Empty stomachs occurred in approximately 40% of the animals harvested each year suggesting that a substantial portion of the population had not fed for at least several hours prior to collection….