The northern harrier, formerly known as the marsh hawk, hunts primarily on the wing and may cover up to 100 miles per day. Its prey, consisting of mostly rodents and small birds, is detected using extremely keen hearing. The adult male is pale gray on the head, back and wings. There is cinnamon-brown spotting on the legs and flanks, and the wing linings and undertail are white. The eyes of an adult male are yellow.
Female plumage is browner overall with dark streaks on the breast.
The female is born with brown eyes which turn yellow at about three years of age. Juveniles resemble adult females, but have gray eyes. This raptor is considered one of the most agile and acrobatic in North America. During the breeding season, the male performs an elaborate courtship flight consisting of a series of U-shaped maneuvers. The nest is a flimsy structure built of sticks and grass on the ground.