Competitive Behaviors Between Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura) During Scavenging

Interference competition occurs when an individual prohibits another’s access to a resource through antagonistic interactions. Despite considerable research on scavenger interactions at carrion, the limited evidence for competitive interactions between Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura) relies upon the frequency of antagonistic interactions without considering other forms of competition. Using remote cameras, we recorded the duration of aggression, scavenging, and vigilance behaviors exhibited by individual Black and Turkey Vultures scavenging stillborn domestic cattle carcasses within flocks composed of one or both vulture species. We tested for differences of durations of each behavior by vulture species, flock composition, and the combined effect of vulture species and flock composition. Surprisingly, aggressive behaviors were rare and their duration did not differ significantly based on vulture species. The clearest trends between our comparisons revealed that the duration of aggression was significantly longer for Black Vultures in single-species flocks, whereas their duration of scavenging was longer in mixed-species flocks. Turkey Vultures in the presence of multiple conspecifics and heterospecifics exhibited longer durations of vigilance. Our results indicated that scavenging Black Vultures exhibited more aggression toward conspecifics than heterospecifics. Our findings identify the complex ways in which Black Vultures compete with Turkey Vultures, beyond simple aggression.