White-tailed ptarmigan wings, square-ended tail, small black beak and short legs with feathering extending to the toes. Adults are long, with the males being only slightly larger than the females. The average weight is . During the summer, the white-tailed ptarmigan is a speckled grayish brown with white underparts, tail and wings. In the fall, the plumage has turned a much more reddish-brown color and white feathers begin to grow through. By winter all the summer brown feathers are lost and the bird is completely white. A further molt in the spring precedes the breeding season and the bird returns to its
Rock ptarmigan the Russian High Arctic overwinters during the polar night and survives by feeding on rich vegetation on and underneath high cliffs where seabird colonies are located in summer.<ref name="FJL/">Dinets, V. (2001) Winter ecology of Willow Ptarmigan "Lagopus lagopus" and Rock Ptarmigan "L. mutus" at the northern limit of their range. "Ornitologia" 29: 326-327 (in Russian with English summary).</ref> During the last ice age, the species was far more widespread in continental Europe. The rock ptarmigan feeds primarily on birch and willow buds and catkins when available. It also eats various seeds, leaves, flowers, and berries of other plant species. Insects