Ptarmigan, a bird of the tundra and high mountains of North America, Europe, and Asia. It is related to the grouse. The ptarmigan is a plump bird, 12 to 15 inches (30 to 38 cm) long, with thickly feathered feet which enable it to run on top of snow without sinking into it. Its color varies with the season. In winter the ptarmigan is white, and difficult to see on snow. In summer it is mostly brown, blending with open ground. In spring and fall, during plumage changes, it resembles snow-patched earth. The male has bright red combs over its eyes during the spring and summer.

The ptarmigan eats seeds, berries, buds, and insects. The nest is built on the ground in a depression sheltered by rocks, logs, and vegetation. The female lays from 6 to 16 eggs. The young are able to run and hide an hour or so after hatching.

The willow ptarmigan is widely distributed throughout the arctic barren lands of both hemispheres and the arctic islands southward into the willow scrub of the subarctic. The rock ptarmigan ranges farther south. Isolated populations of rock ptarmigan live on mountaintops in the Pyrenees, the Alps, Central Asia, and Japan. In North America the rock ptarmigan ranges south to British Columbia, Labrador, and Newfoundland. The white-tailed ptarmigan is native to Alaska and the Rocky and Cascade mountains as far south as New Mexico. It is the smallest of the three species.

The willow ptarmigan is Lagopus lagopus; rock, L. mutus; white-tailed, L. leucurus. All belong to the grouse family, Tetraonidae.