Bull caribou, Photo courtesy of J. Taylor and Map depicting distribution of caribou in North America, Figure courtesy of C Hinterland Who's Who

The caribou’s habitat is an important topic of research because of its link to the survival of the species.  The woodland caribou is found in the old-growth coniferous forests of northern North America. Populations stretch as far west as the Yukon Territory and as far east as Newfoundland and Labrador. The sensitive woodland caribou depend on an untouched and undisturbed habitat, a necessity that is becoming more and more difficult to maintain. 

Two ecotypes of woodland caribou exist: boreal and mountain.  Boreal woodland caribou prefer forested areas, marshes, bogs, shorelines, and islands.  Mountain caribou, on the other hand, spend most of their time in higher elevations on the mountain and forests of the foothills (Edmonds, 1987).  The habitats of caribou vary with seasonal changes and reflect the importance of the rutting and calving periods.  Their seasonal movements most likely serve to diminish their chances of predation.  As a result, most populations of woodland caribou are considered migratory (Bergerud et al, 1990; Cumming, 1992).  However, some populations do not migrate and remain fairly sedentary (Darby and Pruitt, 1984; Cumming and Beange, 1987).

Woodland caribou have both a summer and winter habitat.  Each habitat has different features important to the caribou.  Summer habitats generally have ample supply of food for cow and calf pairs, though some exceptions exist (Bergerud et al, 1990). Winter habitats are equally important but tend to be more dependent on the snow conditions and weather (Wisheu, 2002). Mountain caribou winter in the foothills to escape the difficult conditions present at higher elevations, but spend the more mild summers at these higher elevations.  Boreal caribou on the other hand, use bogs, marshes, and islands in the summer months and resort to dense and deep forests in the winter because of the high winter snow levels in their summer environments (Edmonds. 1987). The primary habitat requirement, consistent across the summer and winter habitats of the woodland caribou ecotypes, is the need for protection against predation during vulnerable times of rutting and calving (Bergerud et al, 1990). Food also plays an important role in habitat selection for the woodland caribou. In the early spring months, woodland caribou of one sedentary population primarily fed on terricolous and lichens.  They also ate the tips of willow and alder twigs. In late spring, the same group of caribou foraged on forbs, deciduous foliage and arboreal and ground lichens. They continued to feed on arboreal and ground lichen until the snowfall in autumn (Darby and Pruitt, 1984).  The mountain caribou ecotype also relied on arboreal lichen in the late winter months and fed heavily on trees during periods of mild weather (Kinley et al, 2003).

Woodland caribou are browsers and display both anatomical and behavioral attributes to aid them in acquiring food resources.  In fact, their browsing habits correspond to fairly unique behavioral adaptations.  For example, female caribou spar with male caribou in winter months in order to compete for food resources.  Many times, the females initiate sparring to acquire the snow craters created by other caribou (Barrette and Vandal, 1990).  The results of one study conducted indicated that the 80% of female sparring occurred over resources.  In comparison, only 21% of adult males and 43% of yearling males sparred over resources during the course of the study.  Given the physical size and strength differences between male and female caribou, it makes sense that the female caribou lost the majority of its sparring matches with males (93/110 cases were unsuccessful) (Barrette and Vandal, 1990).  The snow craters for which caribou compete consist of areas where snow is pushed to the outer edge of an area by the caribou to expose ground lichen.  The long legs of the caribou have specially adapted to make the building of snow craters possible (Banfield, 1974).