Caribou Often Use a Different Forest Each Winter
Mountain caribou do not always return to the same forested site each winter. According to the study's researchers, these results imply that even though a suitable old forest has not recently been occupied by mountain caribou, it could be important winter habitat in future.
Ten years of monitoring caribou movement near Revelstoke, British Columbia finds that individual animals have flexible patterns and may reuse a site some years, but not others.
Early-winter snowfall at lower elevations in the Columbia Mountains varies substantially between years. When snow is deeper than normal, mountain caribou, a threatened ecotype of woodland caribou, roam farther in search of food. These are times when heavy snow blocks access to some food sources, making browse harder to find.
Late-winter ranges are smaller, reflecting the abundance of lichens hanging from trees that caribou can reach once the snowpack higher up the mountainsides deepens and hardens. But these slow-growing lichens do become depleted from repeated years of browsing, causing the animals to choose other late-winter sites in subsequent years.
The lack of fidelity to specific forest stands among winters contrasts sharply with caribou's selection of habitat each summer, when they return to the same high-elevation areas. Caribou likely choose the same location every summer to avoid predators at a time when the ungulates are especially vulnerable.
Heiko U. Wittmer, Bruce N. McLellan and Frederick W. Hovey. 2006. Factors influencing variation in site fidelity of woodland caribou (Rangifer tarandus caribou) in southeastern British Columbia. Canadian Journal of Zoology. 84(4): 537-545.