Laura Erickson's For the Birds

The Rock Ptarmigan, a bird of some of the most sparsely vegetated, rocky areas of the tundra, nests as far north as land exists. The more widespread Willow Ptarmigan sometimes feeds and even nests near Rock Ptarmigans, and the species rarely interbreed.

The male Rock Ptarmigan takes longer than the female to molt from its white winter plumage into summer plumage, though the white feathers grow increasingly dirty before being replaced by the cryptically patterned brown feathers. So during courtship and early nesting, the male is fairly conspicuous, while incubating females are extremely well camouflaged that she is difficult to see from even 6 feet away.