Carnivore-Prey Relationships

The effect of predation on population dynamics of black-tailed and mule deer (i.e., deer) can vary widely, depending on several factors specific to each local circumstance and time period including the amount of forage available for deer, the predator community, weather, disease, and human development. This chapter will provide managers with expected predation rates specific to ecoregion, as a starting point for designing a deer monitoring or management plan. The best documented effects of predation on deer include high black bear predation on neonates in California, mountain lion predation accelerating population decline caused by harsh weather and slowing population recovery in California, mountain lion predation affecting mule deer through apparent competition with white-tailed deer in the northwestern United States and southwestern Canada, and wolf predation causing declines in Sitka black-tailed deer populations on islands in southeast Alaska. Adjusting harvest regulations for mule deer to reach management objectives while accounting for predation can result in dissatisfaction among some stakeholders when predation rates are high and hunting opportunity is limited, as can efforts at carnivore control designed to increase hunter opportunity in such situations. Predation effects on deer populations are complex and the strong public interest requires monitoring programs and public transparency.