Photos by Ron Pera
February and early March are the best times to view Rough-legged Hawks in Skagit County. This winter migrant can be found in open agricultural fields perched on fence posts, farm buildings and the twigs of bushes and small perimeter trees. This slender buteo can easily be overlooked as another Red-tailed Hawk, but take time to observe the differences of this beauty from the tundra.
Identification of this bird is either light or dark morph and unlike the Red-tailed Hawk has few variations. The light morph Rough-legged Hawk is most common in the West. Perched, this bird appears slimmer, more erect and slightly larger than the Red-tailed. The Rough-legged has light feathers on its head and a smaller bill. The chest feathers are white with light brown streaks. A darker belly band is apparent on the female and some juveniles. Wing feathers can appear slightly longer than the tail. In flight, the characteristic broad wings and short tail of a buteo are observed. The distinguishing field mark is on the under-wing. The Rough-legged has a dark carpal or “wrist” patch. The Red-tailed has a dark patagial mark on the leading edge. In adults, the tail is another distinguishing difference, a red tail verses a white base with a dark terminal band. Juvenile Red-tailed Hawks have banded tails. The Rough-legged Hawk is named for the feathers on the legs down to the toes. The Golden Eagle and the Ferruginous Hawk are the only other American hawks to have feathered legs.
This hawk is most active hunting at dusk. It is the only hawk in America known to hover over prey, similar to kites, kestrels and ospreys. Although preferring small mammals, Rough-legged Hawks are known to prey on small birds and take advantage of carrion. In Europe they are known as the Rough-legged Buzzard. Here in North America their primary food source is lemmings, voles and mice. On their tundra nesting grounds, this hawk builds a platform nest consisting of sticks, weed stalks, and sometimes caribou bones lined with moss and grasses. The nest is constructed on a slope or cliff when trees are unavailable. The female lays 2 to 7 eggs, which incubate for up to 31 days then hatch asynchronously. During this time the male does most of the foraging. Larger clutches are known to occur during a high lemming abundance. This cycle known as an irruption or invasion occurs usually 3 to 4 years with higher numbers migrating the following winter to Skagit Valley. Every year all Rough-legged Hawks leave the breeding grounds and migrate in loose flocks southward. Once on the winter hunting sites, these hawks can be seen roosting communally.
A good area to observe this bird in Skagit Valley is the Samish Flats. Located north of Highway 20 travel on Bayview-Edison Road between Padilla Bay and Alice Bay. At the end, turn left and drive to the parking area known as the West 90. A discover pass is required for parking. Other raptors to look for include Northern Harriers, Red-tailed Hawks, Bald Eagles and Short-eared Owls.
Enjoy the many birding opportunities winter brings to Skagit County. Join us on a field trip or head out on your own to hunt down the many winter raptors in this area.
References available upon request.