Influence of weather and density on lamb survival of desert mountain sheep

This report concerns the effect of weather on lamb survival in desert mountain sheep (Ovis canadensis nelsoni) to 6-8 months of age in the River Mountains, Nevada, and how it integrates with density to limit the population. Regression analyses were used to examine relationships between lamb survival and weather variables from 1970 to 1982. Autumn precipitation (Sep-Dec) of the preceding year (during gestation) had a significant (P < 0.05), positive effect on lamb survival. Herd density was significantly (P < 0.05) and inversely related to lamb survival. Spring winds had a positive and significant (P < 0.05) effect on lamb survival. Multiple regression revealed that 87% of the variability in lamb survival was accounted for by autumn precipitation during gestation (52%) and sheep density (35%).