First evidence of collared forest-falcon (Micrastur semitorquatus: Falconiformes: Falconidae) nesting in Argentina and a new case of macaw’s nest usurpation

Abstract

The collared forest-falcon (Micrastur semitorquatus) is distributed from Mexico to the south, the subspecies M. s. semitorquatus reaching Argentina, found in wooded and forested environments. Although it is mentioned that it breeds in the country, to date, no nests of the species have been recorded. Here we report the finding of a nest with two fledglings in forests of the Salta province. The nest was found on a rocky wall at 45 m height, in a hollow that had been occupied by a green macaw (Ara militaris) in the previous reproductive season. We describe the nest, fledglings, vocalizations, and the interaction with the macaws. Because the collared forest-falcon has high site fidelity and is common in the study area, it is probable that events of negative interaction, nest occupation and usurpation with the green macaw will occur in future reproductive seasons.