Variation in cougar (Puma concolor) prédation habits during wolf (Cards lupus) recovery in the southern Greater Yellowstone Ecosystem

摘要

We examined prédation habits of cougars (Puma concolor (L., 1771)) following the recent recovery of gray wolves (Canis lupus L., 1758) in the southern Greater Yellowstone Ecosystem. With the extirpation of wolves in the early 20th century, cougars likely expanded their niche space to include space vacated by wolves, and increased use of habitat better suited to the foraging of a coursing predator, Like wolves. We predicted that as wolves recolonized their former range, competitive exclusion would compel cougars to cede portions of niche space occupied in the absence of wolves. To examine this hypothesis, we radio-tracked cougars and examined their prédation sites from winter 2000-2001 through summer 2009. Variation in foraging by cougars was associated with increasing wolf presence. As wolf numbers increased and the mean distance between wolf pack activity centers and cougar prédation sites decreased, cougars made kills at higher elevations on more north-facing slopes during summer and in more rugged areas during winter. In addition, cougars preyed on a higher proportion of mule deer (OdocoUeus hemionus (Rafinesque, 1817)), consistent with predictions of exploitative competition with wolves. Observed changes in prédation characteristics reflect differences in prédation strategy between cougars and wolves, given that wolves are coursing predators and cougars are ambush predators. These possible prédation effects should be considered when developing management strategies in systems where therecolonization of wolves may occur.