Harris's Hawk

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). 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 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 Harris's hawk are very harsh sounds. The lifespan of Harris's hawk is 10–12 years in the wild, though up to 25 years has been recorded in captivity.

Juvenile. The juvenile Harris's hawk is heavily streaked with white or buff on the underparts, and appears much lighter than the solidly dark-breasted dark adults. …

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., utility 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.

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. Social behaviour is most well documented in the northern subspecies P. u. harrisi. Individuals tend to be larger with more pronounced social behaviours in the southwestern U.S., where environmental conditions are harsher, than in the southeastern U.S. P. u. unicinctus was once thought to be significantly less social than the northern subspecies, but increasing records of social behaviour in the subspecies since the late 1990s suggests a greater extent of sociality in the subspecies than previously recognized.

Breeding. They nest in small trees, shrubby growth, or cacti. The nests are often compact, made of sticks, plant roots, and stems and are often lined with leaves, moss, bark, and plant roots. They are built mainly by the female. There are usually two to four white to blueish-white eggs sometimes with a speckling of pale brown or gray. …

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.