Foraging shifts in a Neotropical Turkey Vulture (Cathartes aura ruficollis) in the presence and absence of a northern migrant (C. a. meridionalis)

Intraspecific competition is believed to play a pivotal role in shaping the structure and resource use of migrant and resident bird communities. We compared seasonal movements and apparent survival of patagially-marked and radio-tagged individuals of a Neotropical subspecies of Turkey Vulture (Cathartes aura ruficollis) in central Venezuela in relation to the presence and absence of a larger, dominant, northern subspecies, C. a. meridionalis. We found that the ruficollis population was partially migratory during the periods when migrants arrived and departed. Tagged individuals used areas with higher and lower proportional forest and semi-open vegetation types, respectively, during the dry season than wet season months to avoid competition with migrants. Moreover, apparent survival of ruficollis was lower during sympatry than allopatry. Our study provided evidence that C. a. meridionalis competed with C. a. ruficollis during their tropical residence period, supporting the hypothesis that intraspecific competition contributes to niche separation between these subspecies. Received 1 November 2022. Accepted 11 August 2023.