Rough-legged Hawk

Bird of the Month: Rough-legged Hawk

By Andrew McCormick

PC: Mick Thompson (Rough-legged Hawk)

PC: Mick Thompson (Rough-legged Hawk)

Scientific Name: Buteo lagopus

Length 21 in

Wingspan 53 in

Weight 2.2 lb (990 g)

AOU Band code RLHA

If you are driving in open country in Washington in winter and see a large light-colored raptor perched on a shrub, it is likely to be a Rough-legged Hawk.  They hunt from low perches or low flight and feed on voles, ground squirrels, mice and sometimes birds it can find on the ground.  They are winter visitors to Washington and can be found in the Skagit Flats in Western Washington and in many places in Eastern Washington in their preferred habitat of open grasslands, brush country and sometimes marshes.

The Rough-legged Hawk is our most northern buteo (pronounced byoo’-tee-oh) having evolved in the circumpolar arctic. In North America the area includes the tundra north of the boreal forest in a wide expanse from Alaska across Canada.  The entire population migrates in late fall to southern Canada and northern United States.

Rough-legged Hawks can be found in both light and dark morphs, with the latter making up almost forty percent of the birds in the east, but only ten percent of those in the west.  The adult light morph Rough-leg will almost always have a light forehead and in general the head will be light colored, differentiating it from the darker headed Red-tailed Hawk.  Most Rough-legs seen in western Washington will have large black carpal patches at the bend or wrist on the underside of the wings.  The wings have a black trailing edge formed by the black tips of the feathers.  The female has a wide black subterminal band on the tail and the male can have several black tail bands (Bechard & Swem).  These raptors have the smallest feet of any of the buteos (Alderfer).

The birds belong to the genus Buteo which is Latin for a species of hawk or buzzard.  Buteos are characterized by large bodies and long, wide, rounded wings on which they soar.  The species name lagopus, hare’s foot, is from the Greek, lagos, a hare, and pous, foot giving reference to the feathered-covered legs.  Rough-legs have feathers all the way to the toes, an adaptation that helps them retain heat in the arctic. Hawk is from the Anglo-Saxon hagoc (Halloway). 

Rough-legs are cliff dwellers and will alternate nesting sites with Gyrfalcons and Peregrine Falcons (Dunne, Sibley & Sutton).  The Rough-leg’s nest is most often built on a cliff but at the edge of the forest it can be in a tree.  It is a mass of sticks and debris lined with grasses.  Usually 3-5 pale bluish-white eggs are deposited.  Incubation is mainly by the female and the eggs hatch in a month.  The first flight will occur after 5-6 more weeks.  Rough-legs eat large numbers of lemmings and other rodents and the success or failure of nests can vary with the yearly fluctuations of their supply of prey.

The remoteness of their nesting sites has protected them from human activity and the Rough-legged Hawk population is doing very well.  Their greatest threats are on the wintering grounds which are heavily used for agriculture.