White-tailed ptarmigan than forest grouse, but still prefers running to flying. It ranges from Alaska and western Canada south to northern New Mexico. Males return from their wintering areas to establish territories on spruce-willow timber line breeding grounds in April. Females arrive in early May and pairs are formed. The white-tailed ptarmigan is the only bird in North America to reside permanently in the alpine zone. Its habitat includes areas of boulders, krummholz, snowfields, rock slides, frost-heaved soil and upland herbage. Even in winter it stays in high valleys and mountain slopes where alder, willow, birch and spruce poke through the snow
Camouflage the brain to vary its opacity. By controlling chromatophores of different colours, cephalopods can rapidly change their skin patterns and colours. On a longer timescale, animals like the Arctic hare, Arctic fox, stoat, and rock ptarmigan have snow camouflage, changing their coat colour (by moulting and growing new fur or feathers) from brown or grey in the summer to white in the winter; the Arctic fox is the only species in the dog family to do so. However, Arctic hares which live in the far north of Canada, where summer is very short, remain white year-round. The principle of varying