Demography of Dall's Sheep in the Mackenzie Mountains, Northwest Territories

Abstract

Population characteristics of immature and female Dall's sheep (Ovis dalli dalli) were studied during 1966-73 in the Mackenzie Mountains, Northwest Territories, Canada. The population was largely unaffected by human activities and was probably stationary. Population density on winter range was at least one/km2, apparently lower than densities reported in Alaska and Yukon Territory. A time-specific life table was constructed for females based on 101 ewes collected in 1971-72. We estimated a 75.2% birth rate, an 80% early lamb survival, and a 49% first-year survival. Average annual mortality rate for ewes 1 year old and older was estimated at 14.8%. Longevity of both ewes and rams was at least 14 years. Average life expectancy for yearling ewes was 6+ years, similar to that in other mountain sheep (Ovis canadensis) populations.