Habitat use by woodland caribou near Takla Lake in central British Columbia

Abstract

Caribou (Rangifer tarandus) living in the mountainous areas of British Columbia are usually classified as either northern caribou, which spend much of the winter in low-elevation relatively young forests foraging primarily on terrestrial lichens, or mountain caribou, which winter in high-elevation old subalpine forests foraging exclusively on arboreal lichens. The forest-management practices necessary to conserve caribou differ substantially between these two categories of animals with different life-history strategies. Because of this variability in winter-habitat use, information relating specifically to Takla Lake caribou was required for forest management. To provide this information, we radio-collared 15 female caribou in two subherds in the vicinity of Takla Lake and determined their distribution and movements between January 1996 and May 1998 in relation to topography and vegetation cover. Habitat selection was examined using a classified satellite image. At the landscape scale, Takla Lake caribou avoided low-elevation forests (presumably because of the associated high risk of predation from wolves (Canis lupus)), occupying small seasonally overlapping home ranges (mean 151 km2) at intermediate and high elevations. Within home ranges in all seasons, caribou were most often found in the forest but, relative to availability, they selected forests only during calving. When in the forest, caribou selected open hybrid white-Engelmann spruce (Picea glauca × Picea engelmannii) - subalpine fir (Abies lasiocarpa) forests over lodgepole pine (Pinus contorta) and deciduous forests in all seasons except spring. Caribou selected open spruce-fir stands over dry and closed spruce-fir stands in all seasons except calving. We conclude that caribou feed primarily on arboreal lichens in winter, because the open spruce-fir forests that they use have moderate to high arboreal lichen abundance, deep snow, and few terrestrial lichens. Takla Lake caribou were not typical of either mountain or northern caribou, but as is typical of insular populations of any species, have adapted to the food, topography, and cover types available to them on their mountain islands in a sea of moose (Alces alces) and wolves.