Changes in the population dynamics of the George River caribou herd, 1976-87

Abstract

A recent decrease in the George River Rangifer tarandus herd recruitment was caused both by an increasing calf winter mortality since 1977 and an increase in their summer mortality since 1984. A reduction in pregnancy rate could also be partly responsible for a decline in gross recruitment. Rate of increased of the herd has been negative since 1984. The probable causes of the decline involve the negative effects and interrelation of various factors: decline of the physical condition of females, habitat deterioration on the current calving grounds (former summer range), increase in energy expenditures related to more extensive movements, delayed birth dates, increase in density within their range and especially on calving grounds, increase in wolf Canis lupus populations and exceptionally high snow accumulation during the 1980-81 winter. -Authors