Dall Sheep Reproduction

Nichols, Lyman

I studied the reproductive cycle of Dall sheep (Ovis dalli dalli) in 3 herds in the Kenai Mountains, Alaska. The rut was predicted to extend from 16 November through 19 December 1970, and from 18 November through 18 December 1971. All adult ewes collected throughout the winter were pregnant. Three of 4 yearling ewes were pregnant and no female lambs had reached puberty. Although some long yearling rams appeared physiologically capable of reproduction, they were unlikely to participate in breeding activities because of behavioral constraints. The mean gestation period was 171 days. Fetal growth curves are presented. Lambing dates were not uniform between years or herds. Peak dates of lambing for the 3 herds over 4 yr ranged from 20 May to 31 May. Lambing success averaged 31.8 lambs per 100 ewes and was not significantly different from the statewide average of 36.6. There were negative correlations between increasing winter snow depth and lambing success and between average maximum winter winds and snow depth. Positive correlation was found between average maximum winter temperatures and snow hardness, which, in turn, was negatively correlated with lambing success.

Dall Sheep Reproduction

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