Factors Influencing the Discovery and Use of Carrion by Vertebrate Scavengers From Human-Induced Mass-Mortality Events

Scavengers play critical roles in ecosystem health and stability, and both biotic and abiotic factors can influence scavenger guild dynamics. Carrion is often limited both temporally and spatially on the landscape, but mass mortality events (MMEs)—in which there is an influx of carrion biomass on the landscape—may result in different scavenger community dynamics compared to when carrion is scarcely distributed. In this study, we investigated factors affecting the discovery and use of carrion by a natural, unharrassed scavenger guild during wild pig (Sus scrofa) MMEs conducted at East Foundation’s San Antonio Viejo Ranch in South Texas, USA. We placed trail cameras on wild pig carcasses that were dispatched by Wildlife Services during 4 aerial gunning events between November 2020 and June 2022. Black vultures (Coragyps atratus), coyotes (Canis latrans), crested caracaras (Caracara cheriway), and turkey vultures (Cathartes aura) were documented scavengers at carrion sites. Carcasses were found and consumed more quickly during the summer and when wild pigs were dispatched earlier in the day. Time to carcass discovery increased as canopy cover increased and as distance to nearest water source decreased. Coyotes were more likely to be the species that discovered carcasses in the fall, and their discovery was facilitated by their use of linear features on the landscape. Coyotes started carcass consumption less quickly than avian scavengers and spent a greater proportion of time scavenging at fall over summer sites, whereas vultures spent a greater proportion of time scavenging at summer over fall sites. There was some overlap of site use by all scavenger species, and overlap of activity was greater in the summer than in the fall. Our results suggest that, should land managers wish to utilize their local scavenger guilds for carcass disposal, eradication efforts should be conducted during mornings in summer.