White-tailed Ptarmigan

The White-tailed Ptarmigan is the smallest of the three North American ptarmigan species and the only one whose range extends into the mountains of the contiguous United States, occurring in true alpine tundra above treeline in the Rocky Mountains, Cascades, and (via introduction) the Sierra Nevada. Like its relatives, it molts seasonally from pure white in winter to a mottled brown-and-gray summer plumage that closely matches lichen-covered rock and tundra vegetation, but it is unique among ptarmigan in retaining an entirely white tail year-round.

Key field marks

• Smallest and most compact of the ptarmigan species
• Entirely white tail in all seasons (Willow and Rock Ptarmigan have black tail feathers)
• White wings and belly year-round; mottled gray-brown body in summer, pure white in winter
• Found only in true alpine tundra habitat, generally above treeline

Similar species

Willow and Rock Ptarmigan are both larger and show black tail feathers in every plumage, and neither occurs in the same restricted high-alpine habitat within the lower 48 states used by White-tailed Ptarmigan.

Habitat and Range

White-tailed Ptarmigan are alpine specialists, living year-round above treeline among rocky slopes, talus, and low tundra vegetation, rarely descending far below the alpine zone.

Range

The species occurs in the Rocky Mountains from Alaska and the Yukon south through British Columbia and Alberta to Colorado and New Mexico, and in the Cascade Range of Washington; an introduced population also exists in the Sierra Nevada of California.

Migration

White-tailed Ptarmigan generally make only short elevational movements, shifting to slightly lower, more sheltered alpine slopes or krummholz (stunted tree) zones in the harshest winter conditions.

Behavior

Well camouflaged and tame, White-tailed Ptarmigan often allow close approach in their remote alpine habitat, relying on stillness among rocks and snow to avoid detection.

Voice

Calls include soft clucks and a series of low hoots and cackles, generally quieter than the loud laughing calls of Willow Ptarmigan.

Feeding

Diet includes willow and other alpine shrub buds and leaves, flowers, seeds, and insects in summer, with winter diet shifting heavily to available buds and twigs above the snowpack.

Nesting and breeding

Females nest on the ground in a shallow scrape among rocks or low tundra vegetation, laying 4-8 eggs; pairs are generally monogamous for the breeding season.