Winter habitat relationships of deer and elk in the temperate interior mountains of British Columbia

Abstract Recent work has examined ultimate factors limiting deer (Odocoileus spp.) and elk (Cervus elaphus) populations during winter, such as temperature and forage, but there has been inadequate examination of the influence of snow, especially in concert with foraging decisions. We examined deer and elk habitat selection on winter range in the temperate mountains of southeastern British Columbia. The life histories of radiocollared mule deer (O. hemionus) and elk included seasonal elevational migrations (1,000–1,400 m) and long-distance movements (up to 50–63 km, respectively). Late-winter, deep-snow habitat is limited in wet, mountainous environs and may explain the relatively low densities of ungulates present. Snow-track transects conducted during late winter suggested that deer (mule deer and white-tailed deer [O. virginianus] combined) avoided areas with >40 cm of snow and elk areas with >50 cm. Late-winter snow depth was positively related to elevation and negatively related to slope and solar radiation (hours/day), all of which can be obtained from existing databases and used to map relative late-winter snow depth. The snow-depth model can be used to map potential winter range regardless of current vegetation cover. During late winter deer selected older forests and stands with greater amounts of Douglas-fir (Pseudotsuga menziesii) in the overstory in forested sites. Older stands probably were selected because they had lower snow depths, while mature Douglas-fir trees offered more litterfall forage than other tree species. In contrast, elk selection among forested stands was weak, which suggested that forested stands were not preferred portions of their late-winter habitat. Track data during late winter confirmed that both deer and elk also used areas with low canopy cover, likely to acquire browse. We demonstrated that it is possible to map potential winter range using topographic variables as surrogates for relative snow depth, and we present a model applicable to portions of the temperate interior mountains. We suggest it is important to consider both forage production and snow interception in habitat management because winter energy budgets are a balance between nutrient intake and cost of locomotion.

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