Interannual Variation in Timing and Synchrony of Parturition in Dall's Sheep

Abstract

Timing and synchrony of parturition in Dall's sheep ( Ovis dalli ) were studied in Igloo Mountain, Denali National Park and Preserve, Alaska, from April through July 1988 and 1989. Median ± SD dates of birth were 18 May (±5.1 days) in 1988 and 27 May (±8.8 days) in 1989. Ninety percent of births occurred in a 27-day period in 1988 and in a 36-day period in 1989; interannual variation in timing and synchrony of parturition was pronounced. Mortality of young in this predator-rich environment, however, did not differ between years, suggesting climatic variability may contribute more than predation in constraining timing and synchrony of parturition in Dall's sheep.