A heavily built, ground-nesting bird of the genus Lagopus (family Phasianidae), closely related to the grouse and capercaillie. It inhabits high latitudes of the northern hemisphere and its adaptations to a cold climate include feathered feet and, except in the red grouse, a variety of the willow ptarmigan, completely white plumage in winter. There are three species: willow (L. lagopus), rock (L. muta), and white-tailed (L. leucura) ptarmigans.