Scavenger Assemblage Behavior at Puma Kills in the Santa Cruz Mountains, California

Scavengers structure food webs through consuming carrion and cycling nutrients in ecosystems. Scavenger assemblages are shaped by multiple factors, including intra- and interspecific competition, environmental conditions, and interactions with apex carnivores. Apex carnivores are particularly important for providing carrion resources to these communities, but can also induce fear effects that affect scavenger spatiotemporal behavior (i.e., landscape of fear). We monitored the scavenger community at 50 carcasses of ungulates killed by pumas (Puma concolor) in the Santa Cruz Mountains (California, USA), using motion-activated video camera traps. We hypothesized that obligate avian scavengers (i.e., turkey vultures; Cathartes aura) would visit more kills than opportunistic mammalian scavengers, and that larger mesocarnivores (coyotes [Canis latrans] and bobcats [Lynx rufus]) would spend longer durations at carcasses due to competitive dominance. We also hypothesized that seasonal variation in scavenging activity and earlier carcass detection would lead to greater scavenger activity. We found that turkey vultures were the main scavenger, visiting the most carcasses (n = 22), most frequently being the first species to visit carcasses (n = 14), and spending on average the most time at kills. Larger mesocarnivores had longer mean visit durations, while pumas themselves scavenged from conspecific kills at a relatively high rate. Contrary to our predictions, turkey vultures were the only species with significant seasonal variation-spending more time at kills and finding them more quickly in the dry season. Carcass detection time was weakly associated with the total time a scavenger spent at kills, and scavenger species that discovered more carcasses first were more likely to visit more kills. Our findings highlight the complexity of scavenger assemblages, particularly at kills made by apex carnivores, and contribute to understanding carrion ecology and the role of apex carnivores as ecological brokers in food webs.