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Photo by Jim Parrish
Photo Copyright Jim Parrish
Rough-legged Hawk
Buteo lagopus
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S4S5N
External links
General information
The rough-legged hawk, Buteo lagopus, breeds in northern Canada and Alaska, and migrates south to winter across the United States. On its northern breeding grounds, it is found on tundra, mountain sides, and open forests. During the winter, this species is usually found in grasslands, fields, marshes, sagebrush flats, and other open habitats. In Utah, this bird is found only during the winter, but it is a fairly common in the state during that period.
The rough-legged hawk feeds primarily on rodents, especially voles and lemmings. Occasionally its diet includes birds, insects, and carrion. Pairs are monogamous, and may use the same nest in successive years. Nests are sometimes constructed on the ground, but usually in trees, on cliffs, or on man-made structures. Eggs are laid in May and June. The number of eggs laid fluctuates in relation to prey density; usually two or three eggs are laid, but as many as seven may be laid when rodents are abundant. Incubation is done mainly by the female and lasts 28 to 31 days. Young are tended by both parents, and are able to fly after about five to six weeks. These birds do not breed until they reach two years of age.
Phenology
Hunting crepuscular to considerable extent (Palmer 1988).
Species range
Panboreal. BREEDS: in Noth America, from Aleutians and western and northern Alaska across low arctic and subarctic Canada. See Bechard and Houston (1984) for erroneous nest records. WINTERS: mainly from southern Canada south to southern California, southern Arizona, southern New Mexico, southern Texas, Missouri, Tennessee, Virginia, casually to eastern Texas and the Gulf Coast. Most numerous in winter in the Great Basin and central and northern Great Plains (Root 1988).
Migration
Migrates north from wintering grounds in U.S. March-May; arrives in northern breeding areas in Beaufort Sea area by late April-early May. Southward migration occurs in fall, arriving in the U.S. mostly in September-October; present in southern winter range mostly November-February (Palmer 1988).
Habitat
Nonbreeding: grasslands, field, marshes, sagebrush flats, and open cultivated areas; sometimes rat-infested garbage dumps. Nests on cliffs (typically) or in trees in arctic and subarctic, in tundra, mountain sides, forests with plenty of open ground. Sometimes nests on the ground or on man-made structures. Apparently nests more commonly along coasts and on marine islands. May compete for nest sites with raven, peregrine falcon, and gyrfalcon (latter two often use nests built by rough-legged hawk). May use same nest in successive years.
Food habits
Feeds primarily on microtine rodents and other small mammals (lemmings, mice, ground squirrels, cottontails, etc., including carrion); also eats small birds and game birds, in addition to some insects. Hunts in the air, captures most food on the ground.
Ecology
Productivity fluctuates greatly in relation to prey density. Winter territory encompasses about 10-16 sq km (Zarn 1974); may aggregate and roost in groups where food is abundant. Nesting territory probably as small as 5-6 sq km when prey density high (Palmer 1988).
Reproductive characteristics
Egg dates: May-June in Labrador; May-July (peak in May or June in various areas in Alaska and arctic Canada. Average hatching date in southwestern Alaska: mid-June; mid-July in northern Yukon. Clutch size is 2-7, largest when lemmings are abundant). Incubation, mainly by female, lasts 28-31 days. Young are tended by both parents, fly well at about 5-6 weeks; some may be independent a month or less after attaining flight (Palmer 1988). First breeds probably at 2 years. Number of breeding pairs and/or breeding success usually increase with lemming/vole abundance.
References
- Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's handbook: a field guide to the natural history of North American birds. Simon and Shuster, Inc., New York. xxx + 785 pp.
- Baicich, P. J., and C. J. O. Harrison. 1997. A guide to the nests, eggs, and nestlings of North American Birds, Second Ed. Academic Press, San Diego. 347 pp.
