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Hoary marmots (Marmota caligata) dig burrows in alpine meadows rich in forage as ready refuge from potential predators. Refuge burrows enable hoary marmots to engage in risk-sensitive foraging when they are away from more secure resting burrows on talus slopes. Grizzly bears (Ursus arctos) commonly excavate refuge burrows while hunting marmots, substantially changing the physical characteristics of the burrow by removing earthen material. However, it is not known if marmots continue to use excavated burrows as refuge. We opportunistically inspected 22 burrows excavated by grizzly bears for use by marmots at two sites in northwestern Canada. We found marmot feces at 10 of 22 excavated burrows, indicating that marmots continued to use these burrows after they were excavated by bears. While marmots may dig several refuge burrows in alpine meadows, and bears may substantially modify them while hunting marmots, our observations indicate that some excavated burrows retain value for foraging marmots. However, the extent of their utility is unknown. We postulate several reasons why hoary marmots may use excavated burrows and suggest avenues for further research. [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]

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]