Great Basin Naturalist


We used retrospective analyses to investigate cause-specific mortality and survivorship among 5 populations of mule deer (N = 168 telemetered animals) wintering in the western Great Basin during 1986–1994. These populations existed under similar environmental conditions, but survivorship functions differed among them. Monthly survival ranged from 0.964 to 0.990, and annual survival ranged from 0.643 to 0.884. The proportion of deaths attributed to predation and malnutrition or anthropogenic causes did not differ among the 5 populations. Predation was the leading cause of mortality; mountain lions were responsible for approximately 90% of the deer killed by predators. No difference existed among these populations in the proportion of telemetered deer that were killed by mountain lions, but proportionally more females than males were killed by these large felids. Predation by mountain lions is the primary source of mortality and a widespread phenomenon among the populations of mule deer we investigated.