Mesopredators dominate competition for carrion in an agricultural landscape

The role of carrion in food webs is governed by complex competitive interactions among a wide range of taxa. Although this competition is known to be influenced by several biotic and abiotic factors, relatively few data are available from highly altered landscapes. We investigated the fate of mouse carcasses in an intensively farmed region in Indiana, USA, using remote cameras. Vertebrates removed 234 of 266 (88%) carcasses within two weeks after placement. Raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana) were the predominant scavengers, removing 184 of 197 (93%) carcasses for which a scavenger could be identified. Air temperature influenced carcass removal by vertebrates only at higher temperatures, with fewer carcasses removed as temperatures increased over similar to 22 degrees C. Elevated densities of mesopredators, coupled with the reduced search area for carrion due to the sparse distribution of forested habitat, likely were responsible for the rapid discovery and high level of carcass removal by vertebrates compared to previous investigations. Our data suggest that in agricultural landscapes, the competitive balance for carrion can differ substantially from that found in more pristine habitats. Moreover, the monopolization of carrion resources by abundant mesopredators may have negative consequences for other species that use carrion.