White-tailed ptarmigan cover. The white-tailed ptarmigan was introduced into the Sierra Nevada of California, Wallowa Mountains in Oregon, and Uinta Mountains of Utah in the 1970s. It may have been native here during the early Pleistocene but became locally extinct due to climate changes with greater snow-cover in spring impacting on its breeding season. Alternatively, it may have been unable to colonize the Sierra Nevada because of the barriers provided by the Columbia River and the Great Basin, and the low altitudes of the intervening South Cascades. This herbivorous bird's diet varies seasonally. Nitrogen-rich snow buttercup leaves are favored in the spring
Arctic hare new fur, from brown or grey in the summer to white in the winter, like some other Arctic animals including ermine and ptarmigan, enabling it to remain camouflaged as their environments change. However, the Arctic hares in the far north of Canada, where summer is very short, remain white all year round. The Arctic hare is one of the largest living lagomorphs. On average, this species measures from long, not counting a tail length of . The body mass of this species is typically between , though large individuals can weigh up to . The Arctic hare is a herbivore,