Trophic interactions at avian carcasses: Do scavengers feed on vulture carrion?

Scavenging is a pervasive foraging strategy among vertebrates, yet researchers have only recently begun to reveal the complex implications of scavenging dynamics. Scavenging studies have predominantly used lower trophic level (i.e., herbivore) species as carrion bait, and the few studies that have used higher trophic level (i.e., carnivore) carrion have found these carcass types are generally avoided by vertebrates or scavenged by fewer species than similarly sized herbivore carcasses. No studies have assessed the fate of carcasses of obligate scavengers. To investigate potential differences in scavenging dynamics among avian carrion representing different guilds and trophic levels, we conducted scavenging trials using 20 replicates of two obligate scavenger species (i.e. black vulture, Coragyps atratus; turkey vulture, Cathartes aura) and two lower trophic level species, chicken (Gallus gallus domesticus), and mallard (Anas platyrhynchos). Carcass trials were conducted at the Savannah River Site, SC, USA, and monitored with remote cameras. We hypothesized carcasses of vultures would persist longer and have a distinct scavenging community compared to lower trophic level carcasses (mallard and chicken). As expected, turkey and black vulture carcasses persisted in the environment longer, were less likely to be entirely consumed by vertebrate scavengers, and had a different scavenging community than mallard and chicken carcasses. These results contribute to the growing body of evidence suggesting higher trophic level carrion is exploited differently by vertebrate scavengers. Our findings suggest nutrients derived from vulture carcasses are likely largely reincorporated into lower trophic levels.

Automated summary

Scavenging is a common foraging strategy among vertebrates, but the complex implications of scavenging dynamics have only recently been revealed. Previous scavenging studies have mainly focused on lower trophic level species as carrion bait, with fewer studies on higher trophic level carrion. These studies have found that higher trophic level carcasses are generally avoided or scavenged by fewer species compared to similarly sized herbivore carcasses. This study investigated potential differences in scavenging dynamics among avian carrion representing different guilds and trophic levels. The results showed that vulture carcasses persisted longer, were less likely to be entirely consumed by vertebrate scavengers, and had a different scavenging community compared to lower trophic level carcasses. These findings contribute to the growing evidence that higher trophic level carrion is exploited differently by vertebrate scavengers. Nutrients derived from vulture carcasses are likely reincorporated into lower trophic levels.