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Motion‐sensitive cameras are commonly used to monitor wildlife occupancy rates; however, few studies have assessed whether data from cameras are correlated with density estimates obtained from more traditional labor‐intensive methods such as those based on capture‐mark‐recapture. We used data from a boreal forest community to test whether camera data were correlated with densities estimated from independent monitoring methods. We placed 72 covert cameras in the forest around Lhù'ààn Mân' (Kluane Lake), Yukon, Canada, for 7 years and tracked changes in population densities by camera hit rates. We independently estimated population densities of snowshoe hares (Lepus americanus) and red squirrels (Tamiasciurus hudsonicus) using capture‐mark‐recapture via live trapping, and Canada lynx (Lynx canadensis), coyotes (Canis latrans), and moose (Alces americanus) by snow track transects. Density estimates obtained from conventional aerial surveys were also periodically available for moose. Except for red squirrels, camera hit rates were highly correlated with population density estimates obtained by traditional methods, including across a large range of estimated densities corresponding to cyclic population dynamics in several species. Accordingly, we infer that motion‐sensitive cameras could supplement or replace traditional methods for monitoring key species in boreal forest food webs. Using cameras to monitor population change has several advantages; they require less effort in the field, are non‐invasive compared to live‐trapping, include multiple species at the same time, and rely less on weather than either aerial surveys or snow track transects. Tracking changes across the vast boreal forest is becoming increasingly necessary because of climate and landscape change and our data validate the use of motion‐sensitive cameras to provide a useful quantitative method for state‐of‐the‐environment reporting. [ABSTRACT FROM AUTHOR]

Surveillance of endoparasites at the host community level is rarely reported for ungulates. Yet, changes in the composition and abundance of species in ungulate assemblages, coupled with environmental and climate change, bring into focus the need for baseline data on endoparasite occurrence in host species at the community level. We investigated the prevalence and intensity of eggs of endoparasites in feces of a dynamic boreal ungulate community in Yukon, Canada, that included reintroduced bison (Bison bison), as well as introduced elk (Cervus canadensis), naturally colonizing mule deer (Odocoileus hemionus), and resident populations of caribou (Rangifer tarandus), moose (Alces americanus), and thinhorn sheep (Ovis dalli). We also examined the change in endoparasite prevalence and intensity in bison fecal samples collected eight years apart. The prevalence of eggs detected in feces differed across species for most endoparasite groups. We also provide new records of several endoparasites in novel hosts or new geographic records. We detected a substantially greater prevalence and intensity of trichostrongyle-type eggs in bison feces between samples collected eight years apart. Our data emphasize the need for targeted pathogen surveillance programs to monitor the movement of various ungulate and associated endoparasites. This is particularly pertinent since our data potentially supports evidence for the continued northward expansion and host switching of protostrongylid species, which may have health implications for animals at a new interface. [ABSTRACT FROM AUTHOR]

Groundberries are an important component of the flora of the boreal forest and provide seasonally important food for many birds and mammals, as well as local people in northern Canada. Here, we ask whether there has been a change in the cover of groundberries in the Yukon boreal forest over the last two decades. We monitored five common species at undisturbed forest sites spaced 300 km apart. At our Kluane site, we monitored 710 fixed quadrats per year for 26 years (1997–2022), and at Mayo 500 quadrats per year for 18 years (2005–2022). The cover of four species, Arctostaphylos uva-ursi (L.) Spreng. (bearberry), Arctostaphylos rubra (Rehder & E.H. Wilson) Fernald (red bearberry), Empetrum nigrum L. (crowberry), and Geocaulon lividum (Richardson) Fernald (toadflax), declined annually by 0.2%–0.8% at both sites. In contrast, Vaccinium vitis-idaea L. (lingonberry) increased annually by 0.5% and 0.8%. We tested whether increases in summer temperature and rainfall were correlated with the observed changes but found no significant relationships. These boreal plants are changing in abundance, but we have limited data on the extent and speed of these changes. We recommend experiments to understand the cause(s) of these changes in groundberry productivity. Our study is a start in monitoring important berry species in this critical ecosystem of northern Canada. [ABSTRACT FROM AUTHOR]

Limited information exists on mercury concentrations and environmental drivers of mercury bioaccumulation in high latitude terrestrial carnivores. Spatial patterns of mercury concentrations in wolverine (Gulo gulo, n = 419) were assessed across a 1,600,000 km2 study area in relation to landscape, climate, diet and biological factors in Arctic and boreal biomes of western Canada. Hydrogen stable isotope ratios were measured in wolverine hair from a subset of 80 animals to assess the spatial scale for characterizing environmental conditions of their habitat. Habitat characteristics were determined using GIS methods and raster datasets at two scales, the collection location point and a 150 km radius buffer, which was selected based on results of a correlation analysis between hydrogen stable isotopes in precipitation and wolverine hair. Total mercury concentrations in wolverine muscle ranged >2 orders of magnitude from 0.01 to 5.72 μg/g dry weight and varied geographically, with the highest concentrations in the Northwest Territories followed by Nunavut and Yukon. Regression models at both spatial scales indicated diet (based on nitrogen stable isotope ratios) was the strongest explanatory variable of mercury concentrations in wolverine, with smaller though statistically significant contributions from landscape variables (soil organic carbon, percent cover of wet area, percent cover of perennial snow-ice) and distance to the Arctic Ocean coast. The carbon and nitrogen stable isotope ratios of wolverine muscle suggested greater mercury bioaccumulation could be associated with feeding on marine biota in coastal habitats. Landscape variables identified in the modelling may reflect habitat conditions which support enhanced methylmercury transfer to terrestrial biota. Spatially-explicit estimates of wet atmospheric deposition were positively correlated with wolverine mercury concentrations but this variable was not selected in the final regression models. These landscape patterns provide a basis for further research on underlying processes enhancing methylmercury uptake in high latitude terrestrial food webs. [ABSTRACT FROM AUTHOR]

Some mammal species inhabiting high-latitude biomes have evolved a seasonal moulting pattern that improves camouflage via white coats in winter and brown coats in summer. In many high-latitude and high-altitude areas, the duration and depth of snow cover has been substantially reduced in the last five decades. This reduction in depth and duration of snow cover may create a mismatch between coat colour and colour of the background environment, and potentially reduce the survival rate of species that depend on crypsis. We used long-term (1977–2020) field data and capture–mark–recapture models to test the hypothesis that whiteness of the coat influences winter apparent survival in a cyclic population of snowshoe hares (Lepus americanus) at Kluane, Yukon, Canada. Whiteness of the snowshoe hare coat in autumn declined during this study, and snowshoe hares with a greater proportion of whiteness in their coats in autumn survived better during winter. However, whiteness of the coat in spring did not affect subsequent summer survival. These results are consistent with the hypothesis that the timing of coat colour change in autumn can reduce overwinter survival. Because declines in cyclic snowshoe hare populations are strongly affected by low winter survival, the timing of coat colour change may adversely affect snowshoe hare population dynamics as climate change continues. [ABSTRACT FROM AUTHOR]

Climate warming is causing asynchronies between animal phenology and environments. Mismatched traits, such as coat color change mismatched with snow, can decrease survival. However, coat change does not serve a singular adaptive benefit of camouflage, and alternate coat change functions may confer advantages that supersede mismatch costs. We found that mismatch reduced, rather than increased, autumn mortality risk of snowshoe hares in Yukon by 86.5% when mismatch occurred. We suggest that the increased coat insulation and lower metabolic rates of winter‐acclimatized hares confer energetic advantages to white mismatched hares that reduce their mortality risk. We found that white mismatched hares forage 17–77 min less per day than matched brown hares between 0°C and −10°C, thus lowering their predation risk and increasing survival. We found no effect of mismatch on spring mortality risk, during which mismatch occurred at warmer temperatures, suggesting a potential temperature limit at which the costs of conspicuousness outweigh energetic benefits. [ABSTRACT FROM AUTHOR]

Variation in coat colour within mammal species is of enduring interest, likely because of its potential to be either adaptive or maladaptive. Coat colour in the genus Lynx tends to be stable, with little variation within species compared to that of other felids. Canada lynx (Lynx canadensis) have coats that typically are silver grayish in winter and reddish brown in summer with dark spots, and black hairs on the tips of their tails and ears. A rare pallid colourmorph is occasionally observed, suggestive of partial albinism. Here, I report the first record of a melanistic Canada lynx. The individual was photographed during summer in the Yukon (Canada). It had a black coat containing whitish gray guard hairs throughout, as well as whitish gray hairs in the facial ruff and the rostrum and dorsal regions. There are only a small number of records of coat colour polymorphisms in the genus Lynx. The adaptive significance of melanism in lynx is unknown, but the loss of camouflage when hunting during winter is likely maladaptive. [ABSTRACT FROM AUTHOR]

The bat fauna of northwestern Canada remains poorly known, principally owing to a lack of dedicated surveys across this vast region. To better assess the diversity of bats in the region, we compiled records from several acoustic survey projects and capture sessions whose purpose was to inventory bats in Yukon and northwestern British Columbia (BC) from 2013 to 2018. During our surveys we obtained the 1st apparent acoustic records for Yuma Myotis (Myotis yumanensis), Californian Myotis (M. californicus), Long-eared Myotis (M. evotis), Silver-haired Bat (Lasionycteris noctivagans) and Eastern Red Bat (Lasiurus borealis) from this region. We also captured 2 Long-eared Myotis in northwestern BC. Additionally, our surveys provided range extensions of Northern Myotis (M. septentrionalis), Long-legged Myotis (M. volans), and Hoary Bat (Lasiurus cinereus). Finally, by deploying bat detectors in late autumn, and in some cases throughout the winter, we provide data about seasonal patterns for bat activity in some locations, revealing that bats in northwestern BC may be active as late as 29 October and emerge as early as 30 March, a pattern similar to that observed in southern BC. By combining data from several disparate surveys, conducted for different reasons by different researchers, we were able to provide a fuller picture of the bat fauna of this vast region. Our data provides further evidence that the bat fauna of northwestern Canada is richer than previously documented. [ABSTRACT FROM AUTHOR]

Fur trapping is an important source of mortality for wolverine (Gulo gulo) in northern Canada. However, few populations are monitored for harvest sustainability. An examination of harvest data can be useful to identify areas of concern and direct appropriate management interventions. We used 27 years of harvest data (1988–2014) to examine patterns of wolverine harvest in the Yukon (Canada), where trapping permits are spatially explicit and there are no quotas. We identify spatiotemporal patterns in estimated harvest density, and trapping behavior by fur trappers. We also examined estimated harvest rates and availability of harvest refugia to evaluate if harvest was sustainable. The mean annual harvest in Yukon was 132 ± 31 wolverines, and there was no significant trend over time. Most trappers harvested wolverines infrequently, but 12% of trappers were responsible for 50% of all harvested wolverines, indicating that a small number of trappers had an influence on overall mortality. Relatively high mean annual harvest rates (≥ 8%) were estimated in several ecoregions in southwestern Yukon, where much of the human population and roads are concentrated. Conversely, estimated harvest rates were moderate to low (< 6%) in northern and eastern Yukon, which consist largely of remote wilderness. The mean percent area without harvest was 62 ± 16%. Sustained high harvest rates in southwestern Yukon are likely supported by dispersing animals from harvest refugia. Few putative harvest refugia were formally protected; rather, unsued trapping areas constituted temporal de facto harvest refugia. Our study points to the importance of harvest refugia and the persistence of wilderness regions for sustaining wolverine populations. [ABSTRACT FROM AUTHOR]

Few studies have explicitly examined habitat use by shrews (Sorex spp.) in the boreal forest of western North America. We conducted pitfall trapping in six common xeric habitat types in Yukon, Canada, to determine their relative use by shrews. The overall capture rate was 0.47 shrews per 100 trap nights (TN), with a total sampling effort of 3652 TN. Cinereus shrews (Sorex cinereus; 0.25 per 100 TN) were the most common species, followed by dusky shrews (Sorex monticolus; 0.14 per 100 TN) and American pygmy shrews (Sorex hoyi; 0.08 per 100 TN). Shrew capture rates and species richness was low in all habitat types sampled. Cinereus shrews were captured in similar numbers in boreal mixedwood forest and alpine shrub habitats, and rarely in other lowland forest habitat types. Dusky shrews were captured largely in alpine shrub habitats, while pygmy shrews were captured only in lowland forest habitat types. The relative use of alpine shrub habitat by cinereus shrews and dusky shrews was not expected. Our data was limited by low captures; however, we provide a first approximation of the relative use of common forest types and subalpine shrub habitat in the boreal forest of northwestern Canada. [ABSTRACT FROM AUTHOR]

Understanding habitat use by remnant populations of imperiled species can inform conservation efforts. Arctic ground squirrels (AGS; Urocitellus parryii) occupy alpine and boreal forest habitats in southwestern Yukon, Canada, where populations have been monitored since the 1970s. While alpine populations have remained stable, those in the boreal forest collapsed in the late 1990s and have not recovered. Propelled by the region-wide decline of AGS at low-elevation sites, our purpose was to document site occupancy by remnant populations and to identify habitats that are a high priority for monitoring and have potential for conservation. Using walking transects, we surveyed 155 sites in eight study areas for presence of AGS. Model-averaged occupancy probability was 0.643 (SE = 0.066), and the associated detection probability was 0.835 (SE = 0.075). AGS occurrence was strongly related to increasing habitat openness and also positively influenced by anthropogenic habitat and neighborhood occupancy. The availability of open habitat patches and connectivity among colonies within the boreal forest are consequential for the persistence of low-elevation populations of AGS. These factors may be linked to predator avoidance. Shrubification in the boreal forest as a result of climate warming may reduce AGS ability to detect and avoid predators. Recognizing anthropogenic habitats in land-use planning, and managing potential conflicts with landowners, may be important for the persistence and recovery of AGS at the southern edge of their range. [ABSTRACT FROM AUTHOR]

Background: Species of Trichinella are globally important foodborne parasites infecting a number of domestic and wild vertebrates, including humans. Free-ranging carnivores can act as sentinel species for detection of Trichinella spp. Knowledge of the epidemiology of these parasites may help prevent Trichinella spp. infections in northern Canadian animals and people. Previous research on Trichinella spp. in wildlife from Yukon did not identify risk factors associated with infection, or the diversity and identity of species of Trichinella in regional circulation, based on geographically extensive sampling with large sample sizes. Methods: In a cross-sectional study, we determined the prevalence, infection intensity, risk factors, and species or genotypes of Trichinella in wolverine (Gulo gulo) in two regions of Yukon, Canada, from 2013–2017. A double separatory funnel digestion method followed by mutiplex PCR and PCR-RFLP were used to recover and identify species of Trichinella, respectively. Results: We found larvae of Trichinella in the tongues of 78% (95% CI 73–82) of 338 wolverine sampled. The odds of adult (≥ 2 years) and yearling (1 year) wolverine being Trichinella spp.-positive were four and two times higher, respectively, compared to juveniles (<1 year). The odds of Trichinella spp. presence were three times higher in wolverine from southeast than northwest Yukon. The mean intensity of infection was 22.6 ± 39 (SD, range 0.1–295) larvae per gram. Trichinella T6 was the predominant genotype (76%), followed by T. nativa (8%); mixed infections with Trichinella T6 and T. nativa (12%) were observed. In addition, T. spiralis was detected in one wolverine. Out of 22 isolates initially identified as T. nativa in multiplex PCR, 14 were analyzed by PCR-RFLP to distinguish them from T. chanchalensis, a recently discovered cryptic species, which cannot be distinguished from the T. nativa on multiplex PCR. Ten isolates were identified either as T. chanchalensis alone (n = 7), or mixed infection with T. chanchalensis and T. nativa (n = 2) or T. chanchalensis and Trichinella T6 (n = 1)]. Conclusions: Wolverine hosted high prevalence, high larval intensity, and multiple species of Trichinella, likely due to their scavenging habits, apex position in the food chain, and wide home range. Wolverine (especially adult males) should be considered as a sentinel species for surveys for Trichinella spp. across their distributional range. [ABSTRACT FROM AUTHOR]

The boreal forest is the largest intact forest in the world, and a refuge for species experiencing range retractions as a consequence of climate and landscape change. Yet, large tracts of the boreal forest are threatened by the cumulative impacts of climate change, natural resource extraction, agriculture, and urbanization, perhaps warranting a shift in focus from biodiversity conservation in intact wilderness to that in anthropologically modified landscapes. We investigated landscape features that influence the distribution of the endangered little brown bat (Myotis lucifugus) in an urbanizing boreal landscape at two spatial scales. We hypothesized that little brown bat activity would be influenced by proximity to available building roosts, because roosts are a potential limiting factor for boreal bats. Secondarily, we predicted that bats would use potential foraging habitat, such as waterbodies, and would avoid young, cluttered forests at the landscape scale. We conducted acoustic surveys of bat activity at 210 sites distributed across the study area in Yukon, Canada, within 1‐km grid cells. We tested a priori hypotheses with a set of candidate regression models, accounting for spatial autocorrelation. Our hypothesis about the relative importance of anthropogenic roosts was not supported. Little brown bats were equally active in urban areas (high building density) and rural areas (low building density), perhaps because roosts were adequately available throughout the region. Instead, habitat use was driven by the distribution of potential foraging habitat, particularly waterbodies, which are important sources of aerial insect prey. Little brown bats also avoided young (≤100‐yr‐old) forest at the landscape scale (including areas regenerating after fire), which may have been poor foraging or roosting habitat, and used areas with a smaller agricultural and industrial footprint. Our results suggest that waterbodies and mature forest are important little brown bat habitats that should be protected from urban encroachment. Proactive conservation of important habitat for species at risk is still possible throughout much of the boreal forest, where human densities are comparatively low and the urban footprint is currently small. [ABSTRACT FROM AUTHOR]

Identifying habitat features that may influence the survival and fitness of threatened species is often constrained by a lack of information about the appropriate scale for habitat conservation efforts. Canada's Species at Risk Act lists little brown bats Myotis lucifugus as Endangered and there is a need to determine the scale for delineating important summer habitat features that should be protected. We used a 19-y dataset of banded little brown bats in a 15,000-km2 area of southern Yukon, Canada, to examine fidelity to roost sites and potential foraging areas. We captured and banded 4,349 bats during 208 live-trapping sessions at maternity roosts. Adult females used multiple roosts during the maternity period, separated by up to 6.1 km, within foraging areas, to which individuals exhibited fidelity. Our fidelity rates (≤ 60.5%) are the lowest, and roost-switching rates (≤ 35.5%) the greatest, reported for little brown bats. A small percentage (14.0–20.7%) of females banded as juveniles returned to their natal roosts or foraging areas as adults. We infrequently observed long-distance (25–200 km) switching to novel foraging areas (< 1% of banded bats). We established bat houses to mitigate the loss of a cabin roost; 46.3% of the bats banded at the cabin occupied these houses. The longest documented period of roost fidelity was 18 y, by a female banded as an adult. Roost fidelity by returning adult females declined annually by 3.8–5.3% due to natural mortality, roost switching, or dispersal. Having a choice of multiple maternity roosts within a foraging area may permit little brown bats to select optimal microclimatic conditions throughout the maternity season. Given that fidelity to foraging areas may be higher than to specific roost sites for little brown bats, identification of summer habitat based on foraging areas may be a more effective conservation strategy than relying solely on roost sites. [ABSTRACT FROM AUTHOR]

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Recently, a new generation of global positioning system (GPS) collars has become available that provides limited daily location fixes, a relatively long battery life, and are low‐cost, compared to full‐featured GPS collars. However, their performance is untested, and assessing these biases is needed to inform study designs and data analysis protocols. We used stationary tests of 15 Lotek LifeCycle GPS collars – an example of low‐feature GPS collars – to measure the accuracy of location fixes. In addition, we deployed Lotek Lifecycle GPS collars on 153 caribou Rangifer tarandus and 24 bison Bison bison in Yukon and Alaska, to assess their field performance. We examined differences among species, sex, location fix schedule, and latitude, on four performance metrics (FSR, 3D‐V FSR, DOP and DSR). Stationary trials indicated that mean precision (4.3 ± 4.0 m [SD]) and accuracy (6.0 ± 4.7 m) of location fixes was excellent, and FSR was good (87.2%), albeit both were slightly affected by forest canopy cover. Field performance varied by species and sex. Notably, the mean DSR for male bison was dismal (27.4 ± 24.2%) likely because of their behaviour, and the mean FSR, 3DV‐FSR and DOP, for male caribou was poor (FSR = 57.3 ± 2.0%), compared to collars deployed on female caribou (72.2 ± 1.7%) or female bison (77.9 ± 1.4%). We also observed that the VHF transmitters often failed when the collar malfunctioned. Biases in the accuracy and performance of these low‐cost GPS collars should be taken into account when designing studies. Researchers contemplating investing in low‐feature GPS collars require information on their 'real‐world' performance so that they can decide whether they are appropriate for their intended application. Moreover, researchers need to consider biases in their GPS collar data prior to embarking on field studies and when conducting analyses with the data collected from them. [ABSTRACT FROM AUTHOR]

Lead (Pb) is a toxic element which is released as a result of anthropogenic activities, and Pb stable isotope ratios provide a means to distinguish sources and transport pathways in receiving environments. In this study, isotopes of bioaccumulated Pb (204Pb, 206Pb, 207Pb, 208Pb) were examined for diverse terrestrial and aquatic biota from three areas in western Canada: (a) otter, marten, gulls, terns, and wood frogs in the Alberta Oil Sands Region (AOSR), (b) fish, plankton, and gulls of Great Slave Lake (Yellowknife, Northwest Territories), and (c) wolverine from the Yukon. Aquatic and terrestrial biota from different habitats and a broad geographic area showed a remarkable similarity in their Pb isotope composition (grand mean ± 1 standard deviation: 206Pb/207Pb = 1.189 ± 0.007, 208Pb/207Pb = 2.435 ± 0.009, n = 116). Comparisons with Pb isotope ratios of local sources and environmental receptors showed that values in biota were most similar to those of atmospheric Pb, either measured in local aerosols influenced by industrial activities in the AOSR or in lichens (an aerosol proxy) near Yellowknife and in the Yukon. Biotic Pb isotope ratios were different from those of local geogenic Pb. Although the Pb isotope measurements could not unambiguously identify the specific anthropogenic sources of atmospheric Pb in biota, initial evidence points to the importance of fossil fuels currently used in transportation and power generation. Further research should characterize bioavailable chemical species of Pb in aerosols and important emission sources in western Canada. [Display omitted] • Pb isotope ratios were strikingly similar in diverse animals from western Canada. • The bioaccumulated Pb originated primarily from atmospheric aerosols. • Natural geogenic sources contributed little to bioaccumulated Pb. • Pb isotopes suggest aerosol Pb is highly bioavailable. • Fossil fuels may be important sources of bioavailable Pb to fish and wildlife. [ABSTRACT FROM AUTHOR]

The bat fauna of Alaska and northwestern Canada remains poorly known, principally due to a lack of dedicated surveys. To better assess the diversity of bats in the region, we conducted full-spectrum acoustic surveys at several sites in Yukon, Canada. During our surveys we obtained the 1st acoustic records of Hoary Bat (Lasiurus cinereus) and Long-Legged Myotis (Myotis volans) in Yukon. Neither species had been documented previously in the territory, but one or both species were known from adjacent Alaska, British Columbia, and Northwest Territories. Characteristics of certain echolocation calls of Hoary Bats and Long-legged Myotis are difficult to confuse with other species that might also occur in the region. In addition, we made other noteworthy recordings; however, species identification for these other echolocation calls was ambiguous. These 1st records significantly increase our knowledge of the ranges of these bat species in Yukon, Canada. Further acoustic surveys, coupled with live captures, will help us further understand the diversity and distribution of bats in Yukon. [ABSTRACT FROM AUTHOR]

Diurnal roost sites are a critical resource for bats. Despite their importance, we know little about the roosting habits of Little Brown Myotis (Myotis lucifugus) in the boreal forest of northwestern Canada and Alaska. To locate diurnal roost sites and determine minimum distances to foraging areas, we radio-tagged 10 Little Brown Myotis (7 adult females, 3 adult males) in the boreal forest of southwestern Yukon, Canada. All of the females roosted in a single building, with 1 using a bat house for 2 nights. In contrast, the males used a variety of roost sites, including buildings, rock cliffs, and trees, and switched roosts periodically. We observed sex-biased movements, with adult males traveling a significantly shorter distance between their diurnal roost sites and a key foraging area than adult females. Males tended to roost near a key foraging area, whereas radio-tagged females flew >5 km from their diurnal roosts to forage. Our data are some of the first obtained via radio-telemetry for Little Brown Myotis in the boreal forest and confirm that the roosting behavior of the sexes is different. That all of the radio-tagged females primarily used 1 roost site in town and flew relatively far to a key foraging area suggests that these critical resources may be somewhat limiting in our study area. [ABSTRACT FROM AUTHOR]

Large-scale fires are anticipated to increase in frequency in the boreal forest under global climate warming scenarios. To understand concomitant responses by wildlife to fire-induced habitat changes, fecal pellet counts were used to assess Snowshoe Hare (Lepus americanus) use of four age-classes of boreal forest after fire in central Yukon, Canada. Use of stands across a chronosequence of 8-177 years was bimodal. Post-fire Trembling Aspen (Populus tremuloides) stands ≤20 years old had greater densities of Snowshoe Hare pellets (median 156 pellets/dam²) than Trembling Aspen stands 21-70 years old, mixedwood stands 71-120 years old (<17 pellets/dam²), or Western White Spruce (Picea albertiana) -dominated stands 121-170 years old (71 pellets/dam²). Forty stand-level compositional and structural variables were assessed as possible predictors of Snowshoe Hare pellet densities. Multidimensional scaling was used to identify variables (n - 10) that were most strongly related to pellet densities and was followed by multiple regression. Canopy cover of Trembling Aspen <50 cm tall and Western White Spruce si m tall, and deadfall depth, in combination, were the best estimators of Snowshoe Hare pellet densities among stands in the chronosequence (P <0.001. 64.5% variance explained). Although Trembling Aspen <50 cm tall explained the most variance, its canopy cover did not exceed 10%. More Trembling Aspen cover <50 cm tall and greater deadfall depths within the chronosequence were associated with stands ≤20 years old. Peak Snowshoe Hare use occurred in early (≤20 years old) rather than mid-successional (21-120 years old) stands, contrary to use patterns reported elsewhere. The lack of tall understory shrubs likely limited the use of mid-successional stands. [ABSTRACT FROM AUTHOR]

The article investigates the predatory behavior of gray wolf in scavenging of reintroduced scavenging American bison in southwestern Yukon. It cites several incidents of bison predation by wolves in 2007 and 2009 but no wolves were directly observed preying on bison because only the rumen remained in the scene. It cites that several sporadic, aerial, and occasional observations were conducted but none had been reported on scavenging of predation of bison. It states that predation of wolf on bison may have substantial implication for the population dynamics of both species and alternate species, and that scavenging are important ecological processes.

The article discusses the diurnal and nocturnal foraging behavior of little brown bat and great horned owl in Yukon. It states that the application for mist nests are highly recommended to capture bats on the Lubbock River, a meandering river to control the current of water and contains several oxbows. The author emphasized that the net held under water by the weight of the owl which identifies from the puncture wounds or by drowning. Moreover, a large hole in a certain net suggested that the owl may have taken at least one other bat from net while it was not monitored.

Fisher (Martes pennanti) occur broadly across northcentral North America, and are a species of conservation concern in most of western North America. Fisher reach the northwestern edge of their distributional range in the Yukon, Canada; however, their abundance and distribution has been poorly documented there. We used museum collections, trapping records, and sightings to update the relative abundance and distribution of Fisher in the Yukon between 1956 and 2009, with a particular emphasis on the last 3 decades. We compiled 100 records of Fisher that were trapped, observed, or whose tracks were noted in the Yukon. Harvest data suggested that Fisher may be increasing in relative abundance in the Yukon, but densities likely are very low. Anecdotal observations and harvest of Fisher in southwestern Yukon have increased in the last 10 to 20 y and suggest that they may be expanding their range westward. Trapping records and museum collections in adjacent Alaska and northwestern British Columbia corroborate records from the Yukon. Monitoring Fisher will be necessary to confirm changes in the abundance and distribution of Fisher in the Yukon and neighboring jurisdictions. [ABSTRACT FROM AUTHOR]

The diversity and distribution of the terrestrial mammals of the Yukon has not been systematically reviewed since 1975, a time when the occurrences of many species were not well known. Since then, single species and community studies, biological collections and expert observations have increased our knowledge of the land mammals of the Yukon. Taxonomic studies have resulted in some additional species. We provide an update on the diversity and distribution of recent land mammals of the Yukon, including previously unreported range extensions, and include a revised checklist. Research in adjoining jurisdictions has contributed more hypothetical species for the Yukon. The mammalian fauna of the Yukon is in a relatively dynamic state, and human-induced changes, particularly climate warming, will undoubtedly influence mammalian diversity and distributions in the coming decades. [ABSTRACT FROM AUTHOR]

Three adult male Northern Long-eared Bats, Myotis septentrionalis, were captured in mist nets in July 2004 in the LaBiche River Valley, southeastern Yukon. These are the first records of M. septentrionalis in the Yukon. Further survey work is needed to delineate the extent of the range and population structure of this and other species of bats in northwestern North America. [ABSTRACT FROM AUTHOR]

The article describes a study which focuses on the invasiveness and evidence of breeding by house mice in an urban area of Yukon. It suggests that the mice are native to northern India and have migrated to various parts of the world because of human activities. As suggested, the study included mice, which were collected from occupied buildings and outside near unoccupied buildings in Whitehorse and highlights that the mice population consists of two color variants. The article also confirms their existence in cold climates and locations at higher altitudes. It also suggests that the introduction of these mice in Yukon is through unintentional human transport including shipments of food and other goods.

The article focuses on the aberrations in coat color of the American Red squirrels, also known as Tamiasciurus hudsonicus. It informs that aberrations in coat color of Scuiridae are common. It informs that the coat color of the Red Squirrel appeared faded or washed out. The Red Squirrel is considered to be of Isabelline coloration. Isabelline is used for birds that have faded plumage. It informs that the Isabelline color variant of Red Squirrels appears to be quite rare. It further informs that in the late 1980s, near Burwash Landing of Yukon, only two Red Squirrels with Isabelline color were collected.

Twenty Southern Red-backed Voles, Myodes gapperi, were collected in July 2004 in the LaBiche River valley of southeastern Yukon. Specimens were identified using morphological characteristics and analysis of cytochrome b gene sequences. These are the first records of this species in the Yukon. No Northern Red-backed Voles, M. rutilus, were collected and it is not known whether the two species are sympatric or parapatric in the Yukon. Further survey work is needed in southeastern Yukon to better delineate the extent of the northwestern range of this species and the extent, if any, of introgression with M. rutilus. [ABSTRACT FROM AUTHOR]

Hunters may select individuals to harvest based on various traits. Wildlife managers need to be cognizant of these preferences so that they can mitigate undesirable consequences of selectivity, where warranted. American black bears (Ursus americanus) vary widely in coat colour, yet there is no information on hunter selectivity for particular colourmorphs, even though such selection may occur. To test the hypothesis that hunters select non-black colourmorph black bears, I used a database of black bears killed by hunting and other sources of mortality in Yukon, Canada. I compared the percentage of black and non-black colourmorph bears hunted (n = 1664) to those killed by other causes (n = 655). I found no evidence of hunters selecting non-black colourmorph black bears disproportionate to their availability, contrary to predictions by wildlife managers. While some hunters in Yukon may prefer to harvest a non-black colourmorph black bear, several factors (multiple motivations for hunting, shooting the first animal encountered, selection for other traits [e.g., body size], or less willingness to shoot a brown bear [Ursus arctos]), or a combination thereof, may result in colourmorphs being harvested in proportion to availability. [ABSTRACT FROM AUTHOR]

The article reports on an observation of an unusual colored North American porcupine. A Porcupine on the shore of Teslin Lake In Yukon, Canada has been observed on August 5, 2014, that was of a sandy or cream color. There were few observable dark hairs, and the eyes and nose were of a normal pigmentation. The color aberrations such as isabelline and albinism are maladaptive in North American Porcupines, otherwise they would likely be more commonly observed in nature.

The article presents a study investigating on the first record of a brown rat or Rattus norvegicus from the Yukon . It was on July 9, 2010 that researchers have captured a female brown rat in an interior of an occupied house in Whitehorse, Yukon. The captured rat was identified as a brown rat than a black rat or Rattus rattus by its characteristics such as in the head, tails, and its small ears covered with fine hairs. Moreover, the origin of the specie was unknown but is was believed to have been transported by humans from either the Alaskan coast, the inland routes from central North America, or it may be an escaped pet.

Arctic Grayling, Thymalius arcticus, are rarely reported to consume small mammals. We report an American Pygmy Shrew, Sorex hoyi, consumed by an Arctic Grayling caught in southem Yukon, Canada. This is the first record of an American Pygmy Shrew being consumed by an Arctic Grayling, and it confirms that Arctic Grayling will consume shrews (Sorex spp.) when they are available. We suspect that the body size of prey is a limiting factor in Arctic Grayling consuming small mammals, with some species of shrews being small enough for Arctic Grayling to consume. [ABSTRACT FROM AUTHOR]

Colour abenations are hot commonly observed in voles (e.g., Microtus and Myodes); thus, individual observations are of interest. We report two observations of melanism in Tundra Voles, Microtus oecono,nus, collected from central Yukon. These are the second and third records of melanistic Tundra Voles, and the first reports from non-insular populations. [ABSTRACT FROM AUTHOR]

The article provides information on a report on the observation of Sorex palustris, commonly known as American Water Shrew, relative to its predation by an Martes americana or American Marten. It states that the incidence of the predation of American Water Shrew are rare, despite of its large skull which can be easily identified in the stomachs of the predator. It offers a brief information on the live-trapping study of American Marten near Watson Lake, Yukon in relation to shrew predation.

A Pygmy Shrew, Sorex hoyi, was captured in a pitfall trap on the Blackstone River (65°04.6N, 138°10.8W) in central Yukon. This represents a northern range extension of about 110 km for S. hoyi in the Yukon. [ABSTRACT FROM AUTHOR]

Accidental mortality of bats is not often observed or reported in the literature. It may, however, have an impact on population size and structure. We report an observation of 53 Little Brown Bats (Myotis lucifugus) being trapped and drowned in a home-made rodent trap at an abandoned cabin in southern Yukon. Traps of this design may be commonly used in the boreal forest. We recommend not using such traps in cabins that are used by colonies of bats. [ABSTRACT FROM AUTHOR]

Cougar (Puma concolor) have been reported from the Yukon as early as 1944. Despite many sightings, no indisputable, physical evidence of Cougar being present in the Yukon had been obtained. Here, we report on the first. In November 2000, a specimen was secured from near Watson Lake, in southeastern Yukon. Whether this specimen, and the numerous sighting records, are indicative of a low-density breeding population in the Yukon, or represent transients, is unknown. [ABSTRACT FROM AUTHOR]

We report an apparent long-distance, non-homing movement of 3044 ± 60 m made by a dispersing subadult male Deer Mouse, Peromyscus maniculatus, in southeastern Yukon. Our observation is nearly twice the maximum distance previously recorded for non-homing Deer Mice, and apparently the longest dispersal movement recorded for this species. [ABSTRACT FROM AUTHOR]