The Harris's Hawk (Parabuteo unicinctus) is a medium-large sized bird of prey found from North America southward to Central and South America.
Their range extends from the southwestern United States, including Southern California, southern Arizona, New Mexico and Texas south into Baja California in Northwestern Mexico.
Further south they are found in Chile, Colombia, Costa Rica, Ecuador, El Salvador, Nicaragua, Guatemala, Paraguay, Peru, Venezuela, Honduras, central Argentina, Uruguay, and Brazil.
These hawks are sometimes sighted in Western Europe, particularly in Great Britain, but these records are almost certainly from escaped birds since they are very popular in falconry.
Within their extensive range, the Harris’s Hawk is found in semiarid woodlands and brush lands but also in tropical deciduous forests. Usually at elevations ranging from 400 to 1000 m. Nowadays it's also possible to find these birds in some urban areas.
The species only real predators are bobcats or coyotes, capable of pulling down nests within their reach. Their lifespan in the wild is about 10 to 12 years while in captivity they can live 20 to 25 years.
The Harris’s Hawks are beautiful medium-sized hawks with adult specimens looking alike in both sexes, but females being about 35% larger than males. Their size is somewhere between that of the Peregrine Falcon (Falco peregrinus) and the Red-Tailed Hawk (Buteo jamaicensis).
With a length ranging from 46 to 59 cm (18 to 23 in) and wingspan measuring around 103 to 120 cm (41 to 47 in). The average weight of an adult female is about 1 Kg (2.3 lb), but it may range from 0.7 to 1.6 Kg (1.7 to 3.6 lb).
While adult males weight from 0.55 to 0.85 Kg (1.2 to 1.9 lb) with an average weight of about 0.7 Kg (1.6 lb). Harris’s Hawks adults display conspicuous rufous or chestnut patches on shoulders, thighs and underwing coverts while the rest of plumage is a dark chocolate brown.
The Harris’s Hawk legs and feet are yellow-orangish in color, the tarsi are feathered halfway, with black claws and long and powerful talons. The bare facial skin is also yellowish. It has a long dark tail with a white base and with a band near the tip. These raptors also have strong yellow bills with a dark tip.
Juvenile hawks usually have a lighter appearance, with a mostly streaked with buff or cream underpart and less distinct and dullish shoulder patches. The amount of lighter colors is variable among juvenile individuals.
In flight, the underwing whitish primaries become very conspicuous. Occasionally their tail is narrowly barred with many fine dusky colored bars.
Within a variety of calls, these hawks most common calls are low growling sound or an extended, harsh call. Their somewhat "wolfpack" behavior, they usually hunt in groups, which is unusual for raptors. This has earned the Harris’s Hawk the curious nickname of "Wolves of the Sky".
Subspecies / Etymology / Taxonomy
It's English name, Harris's Hawk was given by John James Audubon in honor of his friend, ornithological companion and financial supporter, Edward Harris.
Their Genus name Parabuteo is derived from the Greek word "para" meaning "like" and the Latin "buteo" which refers to a "kind of buzzard".
Hawk species classified in the genus Buteo have broad wings and soaring behaviors, while those in the genus Accipiter are characterized by their short wings and long tails.
So the Harris's hawk is classified in the genus Parabuteo, which makes sense since these medium-sized hawks have broad wings like a Buteo and narrow long tails like an Accipiter.
While the species specific name unicinctus, refers to the white band found at the tip of their tail and is the junction of "uni" which means once and cinctus meaning girdled.
There are 3 recognized subspecies of Harris's hawk.
P. u. harrisi - This subspecies is found in Texas, eastern Mexico, and throughout much of Central America.
P. u. superior - They are found in Arizona, Baja California, Sonora, and Sinaloa. It was believed that they had longer tails and wings and a more blackish coloration than P. u. harrisi. But later studies concluded that physical differences between those 2 subspecies weren't relevant which put the validity of the subspecies segmentation in question.
P. u. unicinctus: It's found only in South America, and is smaller than the other subspecies.
Diet / Feeding
The Harris's hawk is a carnivore feeding on small animals such as other birds, mammals, lizards, and even large insects. They will also eat carrion, if available.
They actively hunt prey by flying low around bushes and thickets, usually in groups of 2 or 3 hawks, and if the flushed prey is able to evade one hawk another may catch it, or they take turns chasing it.
Since they live in groups and cooperatively hunt together as a team these birds are capable of taking down larger prey weighing over 4.4 lb (2 kg). These large prey items include adult jackrabbits, juvenile wild turkeys (Meleagris gallopavo) or the Great Blue Heron (Ardea herodias) and are often shared by the group of hawks.
Other hawk species found in the same region like the White-tailed Hawk, Red-Tailed Hawk or the Ferruginous Hawk hunt mostly jackrabbits and cottontails but are bigger than the Harris's Hawk.
For their size, Harris's hawk has quite large and strong feet, with long talons, and a large and prominent hooked beak when compared to similarly sized raptors, probably because they often hunt large preys.
For comparison, Harris's hawk most common prey in the Southwestern United States is the Desert Cottontail (Sylvilagus auduboni) which usually weighs a maximum of 1.8 lb (800 g).
In this region, they also hunt the eastern cottontail, black-tailed jackrabbit, ground squirrels, woodrats and kangaroo rats, pocket gophers, quail, northern bobwhite, mockingbirds, cactus wren, skinks, and desert spiny lizards.
Further south to the tropics, these hawks take other prey items such as chickens or the introduced European rabbit, while the Common Degu (Octodon degus) comprises about 2/3 of their diet in Chile.
The courtship in this species may involve 2, 3, or even more birds, and includes behaviors such as soaring, circling, and diving. Sometimes males perform a vertical dive of several hundred feet, just to land near or even on the back of a female.
Much like they do when hunting the Harris's Hawk also cooperates in nesting, and very often there will be two males and one female attending a single nest and raising the young.They may also breed as a single adult pair or in more complex social units that vary with as many as 7 hawks, both adults, and juvenile birds.
The nest is mostly built by the female, normally in small trees such as paloverde or mesquite, shrubby growth, or in the arms of giant saguaro cactus.
The nest itself is a bulky structure made of sticks, plant roots, and stems, often lined with twigs, leaves, grass, moss, and bark. Throughout the nesting cycle, leafy twigs will be added to the nest, that may be reused several times.
Normally standing at 12 to 25 feet above ground, sometimes it may be built higher on taller trees or even powerline towers. After courtship females lay between 1 and 5 eggs, but normally 3 or 4 eggs are laid in a single clutch.
The eggs are white or pale bluish-white in color occasionally covered with some brown, pale brown or gray speckling. The incubation period lasts around 33 to 36 days and is done mostly by the female, yet, males may take short turns sitting on the eggs.
The males function is to bring food to the incubating female, and after birth to the younglings. At birth, nestlings are light buff in color but after about 5 to 6 days they turn into a rich brown coloration.
The young begin to explore out of the nest after about 38 to 40 days, gradually developing into full flight at 45 to 50 days. This species breeds all year long, and females may breed two or three times per year.
The young Harris's hawks may stay with their parents up to 3 years of age, during that time they will help to raise later broods.
Conservation status and major threats
The Harris's hawk is listed as a "Least Concern Species" in the IUCN Red List, they are also listed in Appendix II of CITES. In the United States, they are protected from harassment and illegal shooting by the Migratory Bird Treaty Act.
Even so, the species has been extirpated from some areas of its range such as the lower Colorado River Valley. There have been some attempts to reintroduce these hawks in these areas.
In the past, the Harris's Hawk was also threatened by illegal collection for falconry, at least in some areas.
Did You Know?
The deathstalker scorpion is considered one of the most dangerous scorpions species.
Species: P. unicinctus
P. u. harrisi
P. u. superior
P. u. unicinctus