A Near-Total Decline in Caribou on Prince of Wales, Somerset, and Russell Islands, Canadian Arctic

Abstract

The number of caribou (Rangifer tarandus) on Prince of Wales, Somerset, and Russell islands in the south-central Canadian Arctic declined by 98% in 15 years, from an estimated 6048 (16% calves) in 1980 to an estimated 100 (0% calves) in 1995. Those estimates were obtained by systematic aerial surveys that used the same design and methods and comparable survey coverage. We do not have the data needed to determine the rate of decrease between 1980 and 1995 or its possible causes. There is no evidence for large-scale winter mortality in any one year or few consecutive years. A probable explanation for the decline is consequential reductions in long-term survival rates, both of breeding females and of calves in their first year of life, associated with continued caribou harvesting and markedly increased wolf (Canis lupus) predation on the dwindling number of caribou through the 1980s and early 1990s. The delay in detecting the decline and the lack of understanding of its causes will handicap the development of an ecologically sound recovery plan. As previous caribou declines have been followed by recovery, some comfort may be drawn from the likelihood of unaided recovery. However, the number of caribou has declined to the point where recovery will be tenuous and lengthy, at best. Unaided recovery could easily fail to occur, so we should not be complacent, especially as extirpation of these few remaining caribou would remove a distinct genetic group and reduce the biodiversity of caribou on Canada’s Arctic Islands.