Busarellus nigricollis distribution includes Mexico, through all of Central America, to most of South America to the east of the Andes, limited to the south including Bolivia, Paraguay, the north of Argentina and Uruguay.

Prefers rain forest, flooded forest and flooded land including rice fields. Found up to 800 meters.

Nest is usually placed in a large tree, frequently near water, but sometimes in shade trees in coffee plantations or other suburban areas. The nest is lined with green leaves. Between three and five eggs are laid, dull white, spotted with pale yellow-brown or red-brown, and a few darker freckles. No further information.

The Black-collared Hawk lives on a diet mainly composed of fish. Also water bugs and occasionally lizards, snails and rodents.

This species has a large range, with an estimated global extent of occurrence of 8,600,000 km2. It has a large global population estimated to be 100,000-1,000,000 individuals (Ferguson-Lees et al. 2001). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.

Sedentary, but nomadic if water levels change.