UNUSUAL CONCENTRATION OF BLACK-CHESTED BUZZARD-EAGLES IN CENTRAL ARGENTINA

LÓPEZ, C.; GRANDE, J. M.; OROZCO-VALOR, P. M.

JOURNAL OF RAPTOR RESEARCH

RAPTOR RESEARCH FOUNDATION INC

Lugar: Lawrence, Kansas; Año: 2017

0892-1016

In birds, gregariousness has been traditionally explained as a way to reduce individual predation pressure or to enhance foraging (Beauchamp 2010), although bird aggregations can also be the result of reproductive or social behavior. Despite being generally solitary, some raptor species congregate in groups for feeding, roosting or migrating. The Black-chested Buzzard-eagle (Geranoaetus melanoleucus) can aggregate in moderate numbers in roosts or predictive foods sources. Here we describe an unusual aggregation of 113-126 eagles for at least a month in a 30 km road section in western La Pampa, Central Argentina. The unusual aggregation seems to be related to a population explosion of Common Yellow-toothed Cavies (Galea musteloides) after an unusually rainy year linked to "El Niño" phenomenon. These and other records of Black-chested Buzzard Eagle aggregations suggest the existence of some migratory/dispersive movements in this species. Further studies are needed to assess the factors determining these unusual eagle concentrations in this species.