- 18.1–23.2 in
- 40.6–46.9 in
- 18.2–31 oz
- 27.3–57.6 oz
- Bay-winged Hawk (English)
- Buse de Harris (French)
- Peuco castellano (Spanish)
- The Harris's Hawk nests in social units that vary from an adult pair, to as many as seven individuals, including both adults and immatures.
- Cooperatively hunting groups of Harris's Hawks are more successful at capturing prey than individuals hunting alone. Hawks with more than two members in their group have higher survival rates.
- Although most North American Harris's Hawks nest in spring (March through June), some females lay a second and even a third clutch regardless of whether their first breeding attempt fails or succeeds. Eggs or young have been recorded in every month of the year. Multiple clutches often occur when plentiful food is available.
- Older nestlings and subadults sometimes seem to play by chasing insects, or jumping on sticks in an imitation of prey capture.
- Electrocution from unshielded power poles is a danger to Harris’s Hawks—they can be killed or lose limbs—but other members of the group sometimes come to the aid of injured individuals, providing them with food.
- The oldest known wild Harris’s Hawk in the wild was a male, and at least 15 years old when he was retrapped and rereleased during banding operations in New Mexico in 2001. He had been banded in the same state in 1986. A captive female lived to be 25 years old.
Harris’s Hawk is a conspicuous bird of desert and savannah environments. They are found in semi-open desert lowlands—often among mesquite, saguaro, and organ pipe cactus—and in some wetland habitats. Territories include high perches such as trees, boulders, and power poles, which the birds use as lookouts, feeding platforms, and for nesting. Access to water is important in hot environments, and birds generally choose areas that include water features such as springs, water catchments and cattle tanks. As development has expanded and human persecution of hawks has declined, Harris’s Hawks have moved into urban and suburban areas throughout their range.
Harris’s Hawks feed mostly on medium-sized mammals such as hares, rabbits, ground squirrels, and other rodents. They may also take quail, medium-sized birds, and reptiles. Individuals in a group of hawks often take turns eating downed prey. They may cache prey in trees to be eaten later. Groups of Harris’s Hawks sometimes defend larger carcasses against interlopers who would take the prey for themselves.
- Clutch Size
- 1–5 eggs
- Egg Length
- 2.2–2.3 in
- Egg Width
- 1.6–1.7 in
- Incubation Period
- 31–36 days
- Nestling Period
- 44–48 days
- Egg Description
- Very pale bluish that fades to white, may have a few pale brown or lavender spots.
- Condition at Hatching
- Helpless and covered in cinnamon colored down.
Nest are bulky structures made up of sticks and parts of cactus, and lined with the same as well as grass, feathers, and down. The breeding pair constructs the nest, with the bulk of the work done by the female. Material may be added throughout the nesting season. Nests can sometimes take on an elliptical shape and are from 18 to 24 inches across, and about 9 inches deep. The inner cup measures about 6 to 14 inches in diameter and 1 to 4 inches deep. More than one nest may be constructed or repaired in a given year, and unused sites are often turned into feeding platforms. Only the breeding female has a brood patch and she does most of the incubation, brooding, and shading of the eggs and nestlings. Other members of the group deliver prey. Depending on available prey, Harris’s Hawk may have more than one brood per year.
Nests are located in almost any relatively tall, sturdy structure, including native saguaro cactus, mesquite trees, cliffs, and introduced trees such as palm, eucalyptus and pine. Nests may also be found on artificial structures such as electrical transmission towers, weather antenna, windmill platforms, and artificial nesting platforms.
Harris’s Hawks are highly social raptors, often found in groups with complex social hierarchies that engage in cooperative hunting and breeding. Groups can consist of up to seven individuals, including both related and unrelated adults of different ages. These birds may help a monogamous breeding couple, or the group may include multiple breeders. These gregarious hawks employ some of the most sophisticated cooperative hunting strategies known in birds, and they feed according to dominance hierarchies within the group. Group members perch in tight proximity, and territories are occupied and defended year-round. Aggressive encounters are infrequent and relatively benign between members of a group, usually taking the form of foot grabbing. A hawk may display aggression by holding its body level to the ground, drooping its wings, and raising the feathers on its head, neck and back. They are agile flyers that, when hunting, may also take to the ground, running and hopping to seize prey. They soar at high altitudes, sometimes plunging into dramatic dives, or even hovering and flying backwards. Sky dancing, consisting of a dramatic dive, may be used as a territorial display, or by males courting females. In one peculiar behavior, backstanding, hawks may alight onto the back of another for minutes at a time, possibly in hopes of securing the particular perch for themselves.
Harris’s Hawk declined across most of their North American range by over 2% per year between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 900,000, with 6% living in the U.S., and 21% living in Mexico. The species rates an 11 out of 20 on the Continental concern Score. Harris's Hawk is not on the 2016 State of North America's Birds' Watch List. Declines are attributed to habitat loss and fragmentation caused by urbanization and development of oil and gas resources. Brush control programs, resulting in the elimination of mesquite habitat, may have also caused declines in some areas. In native habitats, human activity can disrupt breeding and hunting success. As natural perches decline, the hawks increasingly perch on power poles, and electrocution poses a serious threat to these communal birds, sometimes killing several members of a group. In the last few decades as human persecution and hunting of these birds has declined, populations of Harris’s Hawks have been moving into urban and suburban areas. There have been some efforts to reintroduce these birds to their former range along the Colorado River, though success depends on restoring habitat as well. Owing to their social and relatively docile nature, young birds are sometimes taken by falconers, which may also compromise populations.
- Dwyer, James F. and James C. Bednarz. 2011. Harris's Hawk (Parabuteo unicinctus). In The Birds of North America Online, No. 146 (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York.
- North American Bird Conservation Initiative. 2016. The State of North
America’s Birds 2016. Environment and Climate Change Canada: Ottawa, Ontario.
- Partners in Flight. 2012. Species assessment database.
- Sauer, J.R., J.E. Hines, J.E. Fallon, K.L. Pardieck, D.J. Ziolkowski, Jr., and W.A. Link. 2016. The North American Breeding Bird Survey, Results and Analysis 1966–2015, Version 01.30.2015. USGS Patuxent Wildlife Research Center, Laurel, MD.
- USGS Patuxent Wildlife Research Center. 2016. Longevity records of North American Birds.
Resident. Harris’s Hawks do not migrate and hold territories year-round.
Find This Bird
Look out for these raptors on both natural and manmade perches. Harris’ Hawks chose a spot to perch with a good scope of the landscape, so look up. Their dark coloring and predilection to perch in groups will make them stand out from other raptor species in their range.