Adaptive nesting and diet data of the Collared Forest-Falcon (Micrastur semitorquatus) in southern Brazil

Abstract

This note reports the nesting of M. semitorquatus inside a human construction, adding new data on its breeding behavior and diet at the southern limit of its distribution. The study area is located in southern Brazil, about 3 km from Turvo State Park, one of the most important protected areas in southern Brazil. The area is near the Uruguay River, in the municipality of Barra do Guarita, in the northwest region of the state of Rio Grande do Sul. The nest was made inside a human building on an abandoned farm surrounded by a fragmented landscape of forest fragments and cultivated areas. The nest was being used by a female, still incubating the eggs. After the breeding period, and once the adult and young birds left the nest, five pellets and alimentary remains were collected. The alimentary remains found in the nest were composed of bird species, rodents, and a lizard species. Among the birds, we identified three new prey species for the Collared Forest-Falcon: Patagioenas picazuro, Furnarius rufus, and Turdus sp. Therefore, we show that anthropic constructions can be used as alternative nesting sites for this species, which likely foraged in open or agricultural landscapes. These observations demonstrate that the Collared Forest-Falcon has some tolerance to modified environments, an important aspect for its conservation.