Plump, chickenlike bird found in tundra with a mix of rocks and mossy ground cover. Plumage changes throughout the year. In winter, both sexes are pure white. As summer progresses, male develops grayish-brown feathers on head, neck, and back; generally quite splotchy. Summer female is pale golden with intricate black and white markings. Both sexes similar to other ptarmigan species, but smaller with distinctive white outer tail feathers. Generally found singly or in pairs in summer; forms small flocks in winter. Feeds mainly on plants.