Harris's Hawk

About the Harris's hawk

The Harris's hawk is a medium-large bird of prey that breeds from the southwestern United States south to Chile, central Argentina, and Brazil. It comprises two subspecies, the Harris's hawk proper (P. u. harrisi) and the bay-winged hawk (P. u. unicinctus), and in parts of Latin America it is also known as the peuco or dusky hawk. The English name honors Edward Harris, an ornithological companion and financial backer of John James Audubon, who gave the bird its common name. The scientific name blends Greek and Latin roots referring to its resemblance to a buzzard and to the white band that girdles the tip of its tail.

In size, the Harris's hawk falls roughly between a peregrine falcon and a red-tailed hawk, measuring 46 to 59 cm (18–23 in) long with a wingspan of about 103 to 120 cm (41–47 in). As in many raptors, females are notably larger than males — about 35% larger — with U.S. males averaging 701 g (1.545 lbs) and ranging from 546 to 850 g (1.204–1.874 lbs), and females averaging 1,029 g (2.269 lbs) and ranging from 766 to 1,633 g (1.689–3.6 lbs). Adults have dark brown plumage with chestnut shoulders, wing linings, and thighs, a white band at the base and tip of the tail, long yellow legs, and a yellow cere. Juveniles look quite different: heavily streaked with white or buff underneath, with pale wing linings marked by brown streaking and a paler tail band, though their chestnut shoulder patches match the adults' and help with identification. Wild birds typically live 10 to 12 years, while captive individuals have reached 25.

The two subspecies overlap in range in northern South America, as far south as Peru, and it isn't known whether they interbreed there. The southern subspecies, P. u. unicinctus, is smaller with proportionately longer wings and tail, and adults show dark brown underparts streaked with white; the northern subspecies has a completely dark wing underside in mature adults. A third subspecies once proposed for the Arizona-to-Baja California portion of the range is no longer considered well supported.

Behavior and diet

Harris's hawks are famous among raptors for hunting cooperatively, a trait linked to their intelligence and one reason they are so popular in falconry. Groups typically include two to seven birds, organized in a dominance hierarchy with the mature female at the top, followed by the adult male, then younger birds from earlier broods. No other bird of prey is known to hunt in groups as routinely as this species. Hunting techniques vary: in one approach, group members take turns flying ahead to scout until prey is found and shared; in another, hawks spread out around prey and one bird flushes it into the open. The birds will chase prey on foot using their long legs, something most hawks rarely do, and groups of two to four hunters see roughly a 10% boost in success rate for each additional bird.

Most prey is mammalian — ground squirrels, cottontail rabbits, and larger black-tailed jackrabbits weighing more than 2,000 g (4.4 lbs) are all taken, sometimes only possible because hawks are hunting as a pack. Birds ranging from small songbirds up to a great egret or half-grown wild turkey have been recorded as prey, along with reptiles such as lizards and snakes and large insects. Because it regularly tackles large prey, the species has larger, stronger feet with long talons and a more prominent hooked beak than most raptors of similar size.

Breeding pairs nest in small trees, shrubby growth, or cacti, building compact stick nests lined with leaves, moss, bark, and roots, mostly by the female. Clutches usually hold two to four white to bluish-white eggs, sometimes lightly speckled, and incubation takes 31 to 36 days. Nests are frequently attended by three hawks rather than two — sometimes two males and one female, sometimes one male and two females — with the extra bird acting as a helper that assists with hunting and guarding chicks. Young hawks explore outside the nest at 38 days and fledge at 45 to 50 days, and some remain with their parents for up to three years, helping raise later broods.

Range and habitat

Harris's hawks live in sparse woodland and semi-desert, as well as marshes with scattered trees, including mangrove swamps in parts of their South American range. They are permanent residents that do not migrate, and they rely on scattered large trees, utility poles, woodland edges, standing dead trees, boulders, and saguaros as perches and nest supports. The species' range stretches from the southwestern United States south to Chile, central Argentina, and Brazil. The wild population is declining in places due to habitat loss, though the birds have also shown a capacity to move into developed areas under some circumstances.

Conservation status

The Harris's hawk is rated Least Concern (LC) by the IUCN. Its wild population is noted as declining because of habitat loss, even though the species is not considered globally threatened. Known nest predators include coyotes, golden eagles, red-tailed hawks, great horned owls, and flocks of common ravens, and in Chile the black-chested buzzard-eagle is a likely predator; no predation on adult Harris's hawks has been documented in the United States. No targeted conservation programs are documented for the species.