<P> The Harris's hawk (Parabuteo unicinctus) formerly known as the bay - winged hawk or dusky hawk, is a medium - large bird of prey that breeds from the southwestern United States south to Chile, central Argentina, and Brazil . Birds are sometimes reported at large in Western Europe, especially Britain, but it is a popular species in falconry and these records almost certainly all refer to escapes from captivity . </P> <P> The name is derived from the Greek para, meaning beside, near or like, and the Latin buteo, referring to a kind of buzzard; uni meaning once; and cinctus meaning girdled, referring to the white band at the tip of the tail . John James Audubon gave this bird its English name in honor of his ornithological companion, financial supporter, and friend Edward Harris . </P> <P> The Harris's hawk is notable for its behavior of hunting cooperatively in packs consisting of tolerant groups, while other raptors often hunt alone . Harris hawks' social nature has been attributed to their intelligence, which makes them easy to train and have made them a popular bird for use in falconry . </P> <P> This medium - large hawk is roughly intermediate in size between a peregrine falcon (Falco peregrinus) and a red - tailed hawk (Buteo jamaicensis). Harris's hawks range in length from 46 to 59 cm (18 to 23 in) and generally have a wingspan of about 103 to 120 cm (41 to 47 in) They exhibit sexual dimorphism with the females being larger by about 35% . In the United States, the average weight for adult males is about 701 g (1.545 lb), with a range of 546 to 850 g (1.204 to 1.874 lb), while the adult female average is 1,029 g (2.269 lb), with a range of 766 to 1,633 g (1.689 to 3.600 lb). They have dark brown plumage with chestnut shoulders, wing linings, and thighs, white on the base and tip of the tail, long, yellow legs and a yellow cere . The vocalizations of the Harris's hawk are very harsh sounds . </P>

What is a group of harris hawks called