Researchers in South America have recorded the first known examples of black vultures nesting beside predatory species of raptor.
The discovery in Argentina of a pair of black vultures (Coragyps atratus) nesting adjacent to a pair of American barn owls (Tyto furcata), followed an earlier observation where black vultures were recorded nesting beside Chaco eagles (Buteogallus coronatus).
The study, published in the Journal of Raptor Research, details these unlikely examples of nesting neighbours and shares images recorded by on site trail cameras.
The black vulture is a compact, medium sized vulture, with a wingspan up to 150cm and is found through much of the Americas. Although they may eat eggs, newborn animals and small reptiles, they typically scavenge, feeding on carrion and human waste.
These vultures do not construct nests of their own, but will decorate nest sites, and lay their eggs on open ground or in a tree cavity or hollow. Increasingly, black vultures are making use of human structures, nesting in empty buildings or on platforms, as occurred in the two documented cases.
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The first instance came in October 2019 on an abandoned hunting tower in Santa Fe Province, which was topped with a small cabin and terrace.
A pair of black vultures were found to be incubating two eggs inside the cabin, while a pair of Chaco eagles were incubating a single egg on the metre-wide terrace.
Chaco eagles are slightly larger than the black vulture and more powerful, built for hunting predominantly mammalian prey. Although the two species are likely to be tolerant of one another away from nest sites, both would recognise the threat to eggs and nestlings.
Footage obtained from the trail camera showed no interaction between the two species, although a black vulture was observed on the eagle nest in the absence of the adult birds. Subsequently, the single egg in the Chaco eagle nest was absent, while the black vulture nest also later failed.
The second incident occurred in a room of an abandoned house in La Pampa Province, where two empty water tanks, separated by around 50cm, were located.
The black vultures nested in one of the tanks, with a single fledgling appearing in early January 2025. This coincided with the presence of barn owl nestlings in the adjacent tank, and although parent birds were witnessed feeding their respective young, no intraspecific interactions were recorded. Both the nesting attempts proved to be successful.
Although raptor species could be considered a threat to one another in terms of potential predation and competition, this risk was superseded by the benefits identified within each nesting structure and location.
In their letter, researchers Diego Gallego-García, Maximiliano Churruarin, Sergi Gómez-Espí, José Hernán Sarasola and Bracken M. Brown, suggest, “The quality of the sites, and perhaps the scarcity of alternatives, may balance the potential disadvantages deriving from competition. Coexistence during the breeding period could be beneficial if the disadvantages of a potential failure are outweighed by a dilution in the predation risk.”
Find out more about the study.
Top image: nestling black vulture and adult American barn owl carrying prey. Credit: crop of image by DGG, MC, JHS, via Diego Gallego-García et al. Journal of Raptor Research 2026
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