Buteo lagopus
rough-legged hawk
(Also: rough-legged buzzard)

Buteo lagopus has a nearly holarctic distribution. Its geographic range includes most of the United States and all of Canada. Rough-legged hawks spend their winter months in all of the United States except for North Carolina and along the southeast coast of the United States, Kentucky, Alabama, Mississippi, and Arkansas. They are found as far north as Newfoundland and as far west as central Europe and parts of Russia. (Burdick et al., 1936)

Rough-legged hawks inhabit open country and agricultural lands. They are more common in open, early successional areas in which they can soar and seek prey in grasslands and shrublands. Once migration is complete they settle in a suitable nesting spot with enough food nearby to sustain them. Their nests are usually located in trees or on a rocky cliff in which they can overlook a field to catch prey for themselves and their young. (Bechard and Swem, 2002; Burdick et al., 1936; Terres, 1980)

Adult rough-legged hawks average 1026 g and have a wingspan of 134 cm. Total length averages 53 cm. Females are typically the larger gender. Rough-legged hawks have eight different morphs that vary between sex, age, and location. Both sexes exhibit both light and dark morphs; and coloration varies between juveniles and adults.

All adult morphs have a black band that goes along the edges of the underside of their lesser coverts. Adults also all have dark colored eyes. Juveniles have light colored eyes and a dark band along the underside of their wings.

Light morphs of adult females have brown backs and a pattern of increased markings from breast to belly. They have one dark tail band and heavily marked leg feathers. Light-morph adult males have grayish backs. Their breasts are more heavily marked than the belly and multiple bands exist on the tail. A light-morph adult male has heavily-marked leg feathers.

Dark-morph adult males are almost completely black but can be brownish with several white bands on their dark tail. Dark-morph adult females are dark brown with a single black band underneath their tail. Dark-morph juveniles are similar to adult females but exhibit rusty bands underneath their wings and tails. Some individuals have a pale-brown head. (Wheeler and Clark, 1996)

Rough-legged hawks can live up to 18 years in the wild. However, the average life span is about 2 years, often a result illegal shooting or trapping activites or being hit by motor vehicles. Deaths are also a result of hitting man-made structures, such as towers or powerlines. In captivity, the longest living rough-legged hawk was 17 years old. (Bechard and Swem, 2002; Terres, 1980)

Buteo lagopus is usually a solitary species but they occasionally migrate in small groups. Rough-legged hawks typically fly relatively low for birds of their size. They use wing-flapping to reach a preferred altitude, but then usually glide until a perch or a source of food is spotted. They are not known to walk at all, but rough-legged hawks have been spotted scooting down a perch to move closer to a mate or towards food. (Bechard and Swem, 2002)

Home Range

Rough-legged hawks have average territories of 7.3 square kilometers (range 3.6 - 11.8 square km).

These are territorial hawks and generally do not tolerate other nests within 1 km. Rough-legged hawks have been known to share cliff nesting spots with gyrfalcons Falco rusticalus and peregrine falcons Falco peregrinus as well as other rough-legged hawks, but only if the cliff is large and the nests are at least 30 m apart. They will avoid nesting within 60 m of any potential predators of their young, such as golden eagles. They will defend their nests from any bird that threatens them or their young. (Bechard and Swem, 2002)

Rough-legged hawks use sight and vocalizations to communicate with others. They use many calls for communication with other hawks such as a warning call (a high pitch shriek), a courtship call (a low whistle that turns into a hiss), and a "normal" call (a high-pitched whistle into a shriek). Rough-legged hawks are usually silent when away from the breeding site except when in competition with another male or threatened. Males may broadcast 100 calls per minute; much more often than females. (Bechard and Swem, 2002; Terres, 1980)

Rough-legged hawks are swift hunters than spot and capture prey with great precison. Rough-legged hawks will perch high in trees or soar in the sky where they can scan a field or grassy area for small prey. After the prey have been spotted, hawks take flight as quietly as possible (unless already in flight) and circle above a few times to ensure there is no competition with other birds of prey. They dive and spear prey with their large talons. They return to a perch to consume the meal. Typical prey include mice, shrews, black tailed prairie dogs Cynomys ludovicianus, small birds, and other squirrel species (Spermophilus and Tamias). (Burdick et al., 1936; Reid, Krebs, and Kenney, 1997; Seery and Matiatos, 2000)

Their are many known predators of Buteo lagopus but most are predators of nestlings. Humans cause death in many rough-legged hawks by shooting, trapping, hitting them with cars, and building structures that the hawks fly into. Known predators of Buteo lagopus also include artic foxes (Vulpes lagopus), grizzly bears (Ursus arctos), and many other species of birds of prey. Most adult hawks are killed by these predators while trying to scare them away from their nests but artic foxes and other hawks are known to get into the nest and eat the eggs or nestlings. (Bechard and Swem, 2002; Burdick et al., 1936)

Rough-legged hawks help to control the populations of small mammals. Their nests are usually built where there is high prey density.

These hawks are hosts to many parasites, including several nematodes in the genus Physaloptera. A hematozoan documented in this species is a Leucocytozoon species. (Morgan, 1943; Reid, Krebs, and Kenney, 1997; Stabler and Holt, 1965)

There are no known adverse effects of Buteo lagopus on humans.

Buteo lagopus helps control pest (mice, moles, rats) populations through predation. (Reid, Krebs, and Kenney, 1997)

Buteo lagopus is rated as "Least Concern" on the IUCN Red List. Protected under the U.S. Migratory Bird Act, these birds cannot be hunted or killed except for scientific purposes.