- 18.5–20.5 in
- 52–54.3 in
- 25.2–49.4 oz
- Larger than an American Crow; slightly smaller and less bulky than a Red-tailed Hawk.
- Buse pattue (French)
- Ratonero calzado (Spanish)
- The name "Rough-legged" Hawk refers to the feathered legs. The Rough-legged Hawk, the Ferruginous Hawk, and the Golden Eagle are the only American raptors to have legs feathered all the way to the toes.
- Nonbreeding adults eat about a quarter-pound of food daily, or a tenth of their body mass—that’s about 5 small mammals. Nestlings start feeding themselves (swallowing lemmings whole) at about 16 days old. It’s estimated that a brood of 2 nestlings requires 26 pounds of food during the 40 days between hatching to fledging.
- The Rough-legged Hawk’s cliffside nest, a bulky mass of sticks, sometimes contains caribou bones. Nesting pairs need a lot of space: usually only a single pair will nest on a quarter-mile-long cliff. However, the pair may nest within 100 feet of Gyrfalcons, Peregrine Falcons, or Common Ravens.
- Even though they breed under continuous sunlight in the Arctic, Rough-legged Hawks do take a break between about 11 p.m. and 5 a.m., with less activity and vocalizing.
- Rough-legged Hawks have been shown to hunt more in areas experimentally treated with vole urine than in control areas. They may be able to see this waste (as American Kestrels can), which is visible in ultraviolet light, in order to find patches of abundant prey.
- Despite a strong affinity for rodents, Rough-legged Hawks were perceived as a threat to poultry up until the early 20th century. Since they are approachable birds that spend their time in open spaces, they were vulnerable to hunting by farmers. It’s now illegal to shoot raptors and most other wild birds under the Migratory Bird Treaty Act.
- The oldest Rough-legged Hawk on record, a female, was at least 17 years and 9 months old when found in Illinois in 1979.
Rough-legged Hawks breed in open country of the arctic, both in North America and Eurasia. They nest on cliffs and outcroppings in low-lying boreal forest, treeless tundra, uplands, and alpine regions, both inland and coastal. During years of abundant prey their breeding range extends south into forested taiga. In tree-covered areas they hunt over open bogs and other clearings. They winter across southern Canada and most of the United States—west, central, and northeast—in open country, including prairies, shrubsteppes, semideserts, fields, marshes, bogs, and dunes.
On their arctic breeding grounds they eat mostly small rodents such as lemmings and voles, along with some medium-sized mammals—arctic ground squirrels, young hares, pocket gophers—and birds such as ptarmigan and Lapland Longspurs. On their wintering grounds, they eat mostly voles, mice, and shrews. The Rough-legged Hawk hunts on the wing either by pursuing prey or by hovering into the wind and dropping down on prey. They also hunt from elevated perches such as utility poles, trees, fence posts, and haystacks, particularly in winter. They sometimes feed on carrion or steal from other hawks and ravens.
- Clutch Size
- 1–7 eggs
- Number of Broods
- 1 broods
- Egg Length
- 2.1–2.4 in
- Egg Width
- 1.7–1.9 in
- Incubation Period
- 31–37 days
- Nestling Period
- 31–45 days
- Egg Description
- Pale greenish or blue, blotched and streaked with brown.
- Condition at Hatching
- Helpless and covered with thick down.
The nest is a bulky mass of sticks from willows and other arctic plants, sometimes supplemented with caribou bones. It measures 24–35 inches across and 10–24 inches high. The lining may include grasses, sedges, small twigs, molted feathers, and fur from prey. The female spends 3–4 weeks building the nest from materials collected mostly by the male.
The male chooses the cliffside nest site, usually completely exposed rather than protected by overhangs. The pair sometimes reuses a nest or builds a new nest close to an old one. They occasionally nest high in trees or on human-built structures.
Rough-legged Hawks are active during the day, especially at dawn and dusk. They perch alone on fence posts and telephone poles, fly close to the ground with graceful flaps and glides, or hover facing into the wind while searching for prey. They defend winter territories and may spend the night roosting alone, but may also roost communally in stands of conifers or cottonwoods. Rough-legged Hawks are monogamous for at least the duration of the breeding season, and pairs have been reported staying together on wintering grounds. Their minimal courtship displays mainly involve soaring and calling; in some cases the male repeatedly dives and stalls in midair. They often share their nesting cliffs with other species including Gyrfalcons, Peregrine Falcons, and Common Ravens, although they keep other Rough-legged Hawk pairs to a distance of a quarter-mile or more.
Partners in Flight estimates the global breeding population at about 500,000 individuals with 43% of the world’s population breeding in Canada and 44% wintering in the United States. North American populations show no evidence of change and the species is not on the 2014 State of the Birds Watch List. Regionally its numbers fluctuate in response to prey fluctuations, as well as severe weather on breeding grounds. A leading cause of mortality in winter is car strikes while hawks are feeding on roadkill, especially in the Great Basin region. Until at least the 1930s Rough-legged Hawks were subject to hunting by farmers who considered them a threat to poultry.
- Bechard, M. J., and T. R. Swem. 2002. Rough-legged Hawk (Buteo lagopus). In The Birds of North America, No. 641 (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York.
- Crossley, R., J. Ligouri, and B. Sullivan. 2013. The Crossley ID Guide: Raptors. Princeton University Press, Princeton, NJ.
- Ligouri, J. 2011. Hawks at a Distance: Identification of Migrant Raptors. Princeton University Press, Princeton, NJ.
- North American Bird Conservation Initiative, U.S. Committee. 2014. State of the Birds 2014 Report. U.S. Department of Interior, Washington, DC.
- Partners in Flight. 2012. Species assessment database.
- USGS Patuxent Wildlife Research Center. 2015. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2014. North American Breeding Bird Survey 1966–2014 Analysis.
Medium-distance migrant. The entire population moves from arctic breeding grounds to wintering grounds in the U.S. and southern Canada.
Find This Bird
Because Rough-legged Hawks breed in the arctic, your best bet for finding one near you is to wait until winter. Keep an eye out in open country, looking especially for a large, chunky raptor hovering while facing into the wind—similar in style to the much smaller and daintier American Kestrel and White-tailed Kite. Rough-legged Hawks perch on fence posts and utility poles, as well as on the ground or in the slenderest treetops, where other large raptors rarely chance sitting. Watch for them on winter road trips, as their bold tail and underwing pattern, as well as black belly patches, can often be clearly seen even at highway speeds.