CARIBOU IN THE CHANGING NORTH

In the 1950s, caribou (Rangifer tarandus) populations were drastically declining across northern North America. At that time, wolf (Canis lupus) predation, forest fires on winter ranges, and excessive native harvest were thought to be the primary causes of decline. In the early 1970s widespread oil and gas exploration in the Canadian and Alaskan Arctic and the discovery of a giant oil field at Prudhoe Bay again generated national and international interest in caribou and concern for their future welfare. The 1980s have witnessed expansion of most of the major caribou and wild reindeer herds throughout circumpolar areas, including the Central Arctic Herd near the Prudhoe Bay oil field. Behavioral reactions of caribou to oil development have included discontinued range use; avoidance of pipelines, roads, and other oil field structures by female caribou accompanied by calves; habituation to oil field structures and activities by adult males; delayed movements to and from insect-relief habitats; seasonal fracturing of a herd. Assessing the consequences for caribou of northern development is particularly difficult in contrast to other ungulates. The complexity of caribou ecological relations, involving traditional patterns of migratory movements, result in transitory dependence on several different ecosystems and special physiological and morphological adaptations that enable them to use a unique food resource. In addition, their complex social structure varies seasonally.