Demography, prey abundance, and management affect number of cougar mortalities associated with livestock conflicts

Abstract

Balancing the ecological importance of large carnivores with human tolerances across multiple-use landscapes presents a complex and often controversial management scenario. Increasing cougar (Puma concolor) populations in the western United States, coupled with an increasing human population and distribution, may contribute to increased numbers of interactions and conflicts (e.g., livestock depredation) with cougars. We assessed county-level factors associated with mortalities of cougars of different sexes and ages resulting from livestock conflicts in Oregon during 1990–2009. Factors included cougar population density, human population density, proportion of the cougar population that were juvenile males, cougar harvest, prey availability, habitat conditions, and climate measured at the county level. We used generalized linear mixed models and quasi-likelihood Akaike's Information Criterion (QAIC) to rank models. Two of 26 models were competitive (ΔQAIC < 4, ∑w = 0.72) and both contained cougar population density and cougar harvest density; the second-best model also included proportion of juvenile males in the population. From model-averaging, we determined cougar mortalities associated with livestock conflicts increased with increasing cougar population density (95% CL = 0.48–1.37) and decreased with increasing cougar harvest density (95% CL = −0.58 to −0.02). An exploratory model including cougar population density, cougar harvest density, proportion of juvenile male cougars, beef cattle density, relative deer density, and all pairwise interactions was equal to the QAIC-top model from the previous set of 26 models. Under a scenario of a high proportion (0.40) of juvenile males, number of cougar mortalities related to livestock conflicts increased 219% when cougar population density increased from 300/10,000 km2 to 400/10,000 km2. In contrast, the number of cougar mortalities decreased with increasing harvest when cougar population densities were high (500/10,000 km2), but we found no relationship at lower cougar population densities. As beef cattle densities increased, the number of cougar mortalities increased substantially (low deer populations), remained relatively low and constant (average deer population), and decreased (high deer populations). Where landowner tolerance to cougar-livestock conflicts is an issue, wildlife managers may provide expertise to reduce conflicts by increasing density of wild ungulate prey, increasing hunter-harvest, and reducing vulnerability of livestock, depending on factors that may be contributing to conflicts. © 2015 The Wildlife Society.