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
Winter white dwarf hamster able to sense a directional change in photoperiod length, such as in one experiment that demonstrated a transition from 16 hours of light to 14 hours initiates a change to the winter coat. The change to the winter coat can be triggered in the summer by the short day lengths. The change occurs back to the summer coat in the autumn, when the length of the days change again. At internal temperatures hamsters in captivity start later with the changes. The winter colour is less pronounced in them. The eyes of the Winter white hamster are black, unless it is