Pumas (Puma concolor) and black bears (Ursus americanus) are large carnivores that may influence scavenger population dynamics. We used motion-triggered video cameras deployed at deer carcasses to determine how pumas and black bears affected three aspects of carrion acquisition by scavengers: presence, total feeding times, and mean feeding bout durations. We found that pumas were unable to limit acquisition of carrion by large carnivores, but limited aspects of carrion acquisition of both birds and mesocarnivores. Through their suppression of mesocarnivores and birds, pumas apparently initiated a cascading pattern and increased carrion acquisition of small carnivores. In contrast, black bears monopolized carrion resources and generally had larger limiting effects on carrion acquisition of all scavengers. Black bears also limited puma feeding behaviors at puma kills, which may require pumas to compensate for energetic losses through increasing their kill rates of ungulates. Our results suggest that pumas provide carrion and selectively influence species acquiring carrion, while black bears limit carrion availability to all other scavengers. These results suggest that the effects of large carnivores on scavengers depend on attributes of both carnivores and scavengers (including size) and that competition for carcasses may result in intraguild predation as well as mesocarnivore release.

Scavenger Activity at Puma Kills and Experimental CarcassesAllen Scavenger Activity.xlsx