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
Climate of the Arctic twice as much as the global mean temperature has. In 2009, NASA reported that 45 percent or more of the observed warming in the Arctic since 1976 was likely a result of changes in tiny airborne particles called aerosols. Climate models predict that the temperature increase in the Arctic over the next century will continue to be about twice the global average temperature increase. By the end of the 21st century, the annual average temperature in the Arctic is predicted to increase by , with more warming in winter ( than in summer. Decreases in sea-ice extent and thickness are