Risk from a top predator and forest structure influence scavenging by smaller carnivores

Abstract

Large carcasses often attract multiple carnivore species, so subordinate carnivores must weigh the reward of a profitable meal with the risk of being attacked by dominant carnivores. These risk–reward trade-offs are likely influenced by a variety of factors, including scale-dependent risk from dominant carnivores (e.g., short- vs. long-term risk) and the amount of carcass remaining. In the southeastern United States, human hunters provision a large amount of white-tailed deer carrion, which appears to be an important food source for coyotes (a novel top predator), but we know little about how coyotes influence the scavenging behavior of smaller carnivores. In this study, we evaluated the relative importance of risk from coyotes, vulture activity, forest structure, and remaining food on bobcat, gray fox, raccoon, and opossum scavenging by deploying 71 deer carcasses within a managed forest in South Carolina during January 2020 and 2021. We found that coyotes only had direct effects on bobcat behavior, suggesting that competition for carcasses was greatest between these two species. However, the relative importance of long- versus short-term risk from coyotes was dependent on the stage in the scavenging process. Effects from forest structure were also stage-dependent, where tree density and age were related to carcass discovery for bobcats and raccoons, while minimal understory cover facilitated bobcat, gray fox, and opossum scavenging, despite short-term risk from coyotes. Vulture activity appeared to serve as a cue for gray foxes to discover carcasses. Ultimately, we found that risk from coyotes had species-specific and context-dependent effects on smaller carnivore scavenging. This represents some of the first direct evidence of how coyotes alter smaller carnivore behavior in a region where coyotes are a novel top predator. However, forest structure (particularly understory cover) seemed to mediate risk from coyotes, highlighting how habitat can influence predator–predator interactions. Future research should also investigate these interactions during other times of the year and try to quantify how human-provisioned carcasses influence populations and communities.