Harris's hawk (Parabuteo unicinctus), formerly known as the bay-winged hawk, dusky hawk, and sometimes a wolf hawk, and known in Latin America as peuco, is a medium-large bird of prey that breeds from the southwestern United States south to Chile, central Argentina, and Brazil. This bird is sometimes reported to be at large in Western Europe, especially Britain, but it is a popular species in falconry and these records almost invariably all refer to escapes from captivity.
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.
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 has made them a popular bird for use in falconry.
Description
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 and generally have a wingspan of about . These hawks have a brownish plumage, reddish shoulders, and tail feathers with a white base and white tip.
They exhibit sexual dimorphism with the females being larger by about 35%. In the United States, the average weight for adult males is about , with a range of , while the adult female average is , with a range of . 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 Harris's hawk are very harsh sounds.
The lifespan of Harris's Hawk is 10–12 years in the wild and 20–25 years in captivity.
Juvenile
The juvenile Harris's hawk is mostly streaked with buff and appears much lighter than the dark adults. When in flight, the undersides of the juveniles' wings are buff-colored with brown streaking. They can look unlike adults at first glance, but the identical chestnut plumage is an aid for identification.
There are three subspecies of Harris's hawk:
Subspecies
P. u. superior: found in Baja California, Arizona, Sonora, and Sinaloa. P. u. superior was believed to have longer tails and wings and to be more blackish than P. u. harrisi. However, the sample size of the original study was quite small, with only five males and six females. Later research has concluded that there is not as strong a physical difference as was originally assumed. Other ecological differences, such as latitudinal cline were also brought up as arguments against the validity of the subspecies segmentation. P. u. harrisi: found in Texas, eastern Mexico, and much of Central America. P. u. unicinctus: found exclusively in South America. It is smaller than the North American subspecies and the adult's dark brown ventrum is streaked or flecked with white or whitish.
Taxonomy
Robert Ridgway placed Harris' Hawk in its own new subgenus Urubitinga (Antenor) in 1873, and introduced the generic name Parabuteo in 1874. Richard Bowdler Sharpe also separated Harris' Hawk to a monotypic genus, Erythrocnema, in 1874. In his Catalogue of Birds in the British Museum, Sharpe gives an extensive synonymy, with various authors having earlier placed harrisii in three genera and unicinctus in eleven.
Distribution and habitat
Harris's hawks live in sparse woodland and semi-desert, as well as marshes (with some trees) in some parts of their range (Howell and Webb 1995), including mangrove swamps, as in parts of their South American range. Harris's hawks are permanent residents and do not migrate. Important perches and nest supports are provided by scattered larger trees or other features (e.g., power poles, woodland edges, standing dead trees, live trees, boulders, and saguaros).
The wild Harris's hawk population is declining due to habitat loss; however, under some circumstances, they have been known to move into developed areas.
Behaviour
This species occurs in relatively stable groups. A dominance hierarchy occurs in Harris's hawks, wherein the mature female is the dominant bird, followed by the adult male and then the young of previous years. Groups typically include from two to seven birds. Not only do birds cooperate in hunting, but they also assist in the nesting process. No other bird of prey is known to hunt in groups as routinely as this species.