Toco toucan documented as prey for the black-and-chestnut eagle in Argentina

Abstract

With a 64- to 74-cm-long wingspan, the black-and-chestnut eagle (Spizaetus isidori) is a large bird of prey that inhabits the Andean montane forests of South America, from Venezuela to Argentina. Its nests are built in the tops of trees and consist of platforms made of branches and thick sticks. Females lay a single speckled white egg and both parents are responsible for egg incubation and chick rearing. The species is categorized as Endangered by the IUCN.

This eagle's nests have been documented in several countries, making it possible to study the species’ breeding-season dietary habits over a large portion of its range. For example, at nest sites in Colombia, Brazil, and Argentina, observations of prey items brought to nests by adults have been recorded. Birds, particularly cracids (Penelope spp) and domestic hens, are among the most often observed prey taxa, along with mammals weighing between 250 and 6800 g.

On 27 December 2021 within the Yungas forest in Jujuy province, northwest Argentina, we observed an adult black-and-chestnut eagle bring a toco toucan (Ramphastos toco) to its nest as food for the eaglet. We believe that this is the first known record of a black-and-chestnut eagle preying on a toco toucan, whose strong beak, among other characteristics, would normally serve as a predator deterrent.