Black-collared Hawk Busarellus nigricollis in French Guiana: distribution, population size and breeding biology

Abstract

The Black-collared Hawk Busarellus nigricollis is widespread from southern Mexico throughout Central America and east of the Andes in South America. Although rather common in most of its distribution range, little is known about its breeding biology as nests are often built in inaccessible areas. The discovery in 2013 of four nests of this hawk in the coastal region of French Guiana, where it is found near brackish or fresh water in semi-open to open country, allowed us to increase our knowledge of its breeding behavior. The population is estimated at c. 200 pairs. Aerial displays of a breeding pair cover a large area around the nest tree. The nest is a large structure of sticks with a shallow cup lined with finer branches and a layer of twigs with leaves. It is mostly built at a height between 15 and 35 m, in the crown of an isolated tree or in a tree crown emerging above the surrounding vegetation. A single egg per nest is laid in French Guiana. The fledgling period for one nest was 55 days. Both male and female incubate and feed the nestling, although the female's share in both activities is more important. During the entire nesting period male and female add fresh twigs with leaves and to a lesser extent, fine dead branches to the nest.