Any of three or four species of grouse (genus Lagopus) of cold regions. Ptarmigan plumage changes from white in winter to gray or brown, with barring, in spring and summer. The toes are covered with stiff feathers above and below. The common ptarmigan (L. mutus) occurs throughout the British Isles, Europe, and North America, where it is called rock ptarmigan. Ptarmigans survive winter in the Arctic and on mountaintops by browsing shrubs and scratching up lichens and leaves; they burrow in snow to sleep. Males begin group displays in early spring and then separate and display singly in adjoining territories.