Can't bear the competition: Energetic losses from kleptoparasitism by a dominant scavenger may alter foraging behaviors of an apex predator

The interspecific interactions of apex predators are integral to the function of ecological communities, but most studies have focused on understanding their top down effects. Kleptoparasitism (the stealing of procured food) by dominant scavengers can have negative effects on populations and behaviors of apex predators. We captured 7 pumas (Puma concolor) and fitted them with GPS collars to investigate potential kill sites (n = 352), some of which we monitored with camera traps (n = 58). We analyzed whether observed kleptoparasitism by American black bears (Ursus americanus) affected puma energetics and foraging behavior. We found that black bears were the most frequent scavenger of puma kills (72.4%), and we documented bears scavenging puma kills during every month. The top model for bear detection of puma kills included prey size, temperature, and canopy cover, with bears more likely to scavenge from adult black-tailed deer (Odocoileus hemionus columbianus) carcasses in warmer temperatures and under dense canopy cover. When black bear scavenging occurred, pumas spent 22% less time at their kill and incurred energetic losses. In response, pumas shortened their inter-kill intervals by 1.3 days thus increasing their kill rates. Our results demonstrate how a dominant scavenger directly mediates the foraging behavior of an apex predator. These results suggest that community interactions do not necessarily start at the top in top-down systems, and the effects of predators on prey populations can only be understood within their respective ecological communities. (C) 2021 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

Automated summary

Interactions between apex predators and dominant scavengers, such as kleptoparasitism by American black bears on puma kills, can have significant effects on the foraging behavior and energetics of the apex predators. The study found that black bears were the most frequent scavenger of puma kills, leading to pumas spending less time at their kill sites and experiencing energetic losses, which in turn influenced their inter-kill intervals and kill rates. The results highlight the importance of understanding interspecific interactions in ecological communities and how dominant scavengers can impact apex predator dynamics.