SIBLING AGGRESSION IN A NEOTROPICAL RAPTOR, BLACK-CHESTED BUZZARD-EAGLE (GERANOAETUS MELANOLEUCUS): A FIRST REPORT FOR CHILE

Abstract

Avian siblicide is the consequence of extreme sibling aggression in the nest. However, sibling rivalry does not always lead to brood reduction. Depending on the frequency of this behavior in the population and the results of the attacks, siblicide is classified as obligate or facultative. During one breeding season we observed the nests of two different pairs of Black-Chested Buzzard-Eagle in central Chile. The brood size of nests was of 2-3 chicks; then, 5-7 days after hatching, the first sibling aggression were observed in both nests, characterized by vigorous attacks from the both older and younger chick. This behavior extended up to 20-25 days after hatching with no brood reduction. This work represents the first detailed record of sibling aggression in a diurnal raptor in Chile, providing additional evidence for considering the Black-Chested Buzzard-Eagle as a facultative siblicide.