Rough-legged Hawk Life History

Habitat

Habitat GrasslandsRough-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.Back to top

Food

Food MammalsOn 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.Back to top

Nesting

Nest Placement

Nest CliffThe 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.

Nest Description

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.

Nesting Facts
Clutch Size:1-7 eggs
Egg Length:2.1-2.4 in (5.3-6 cm)
Egg Width:1.6-1.9 in (4.2-4.8 cm)
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.
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Behavior

Behavior Aerial Dive (ground/talons)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. Back to top

Conservation

Conservation Low ConcernThere is little information on Rough-legged Hawk population trends, but populations appear to be stable. Partners in Flight estimates a global breeding population at about 500,000 individuals with 43% spending at least part of the year in Canada, and 44% wintering in the United States. The species rates a 10 out of 20 on the Continental Concern Score. Rough-legged Hawk is a U.S.-Canada Stewardship species and is not on the 2014 State of the Birds Watch List. Regionally populations 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. Back to top

Credits

Bechard, Marc J. and Theodor R. Swem. 2002. Rough-legged Hawk (Buteo lagopus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Crossley, Richard, Jerry Liguori and Brian Sullivan. 2013. The Crossley ID Guide: Raptors: Princeton University Press.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center 2014b. Available from http://www.mbr-pwrc.usgs.gov/bbs/.

Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

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