Montana Field Guide

The White-tailed Ptarmigan is a grouse of alpine (above treeline) habitats. It is the smallest grouse in North America (total length 30 to 31 cm, weight 295 to 440 grams), and the only species of grouse with white tail feathers. It possesses cryptic plumage that changes annually from white in winter to grayish-brown in summer. The sexes are similar in body size, shape, and winter plumage.

Breeding season males have a conspicuous necklace of coarsely barred brown and black breast feathers, while female plumage is predominantly brown and black with yellowish barring. Male plumage is generally more brown and gray than in the female. Males possess scarlet eye combs that are especially conspicuous during the breeding season; females have less conspicuous and smaller salmon-colored eye combs. In winter, in addition to the completely white plumage, the legs are heavily feathered to the ends of the toes, creating a snowshoe effect for walking on snow (Choate 1960, Braun et al. 1993).

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

White-tailed Ptarmigan can be differentiated from all other grouse (including other ptarmigan) by their small body size and distinctive white tail feathers. Dusky Grouse often appear at or above treeline in the mountains of western North America, but lack the white tail.

Movements tend to be elevational, from higher breeding grounds to lower wintering grounds, although some birds do not migrate. Distances moved are 0.2 to 22.7 km (in Colorado), with females moving farther than males (Braun et al. 1993). Females may also move up to 30+ km between potential breeding territories early in the breeding season (Martin et al. 2000). In Glacier National Park, birds moved an unspecified distance off of the breeding grounds onto adjacent tundra and valley bottoms by mid-October, and reappeared on the breeding grounds by June (Choate 1963).

Habitats occupied in Montana are similar in structure and composition to other locations in the species' range. These include alpine locations with a wide variety of plant habitats from dry, rocky, windswept areas to perpetually wet and mossy streamside areas; level or gently sloping sites are most favored. Moist vegetation (in recently snow-covered or stream-fed areas) and rocks are present in all areas heavily used by ptarmigan in summer, and in Glacier National Park it is often associated with net-veined willow (Salix nivalis), heath (Phyllodoce sp. and Cassiope sp.), and mosses. They do not occur during summer in forest or shrubby vegetation over 50 cm tall, although limited data from autumn and winter indicate ptarmigan sometimes occupy patches of krummholz (stunted and wind-deformed) trees (Choate 1963; Scott 1982). Nests are built in alpine terrain, in rocky areas or sparsely vegetated, grassy slopes. High fidelity to breeding territories in successive years tends to result in young adult birds searching for vacant territories in the natal area.

In Glacier National Park, males, females and young ate similar plant parts - new shoots, flowers, seeds and fruits (Choate 1963). Their winter diet includes alder catkins, willow buds and twigs (the primary winter food in Colorado is willow buds); also buds and needles of spruces, pines, and firs. Spring and summer diet includes leaves, buds, and flowers of herbaceous plants, willow buds, berries, seeds, and insects (Choate 1963, Braun et al. 1993).

Chicks leave the brood after 8 to 11 weeks. The density of birds was 2.7 per 100 acres. About one-third of territorial males did not get a mate. The average adult mortality was 29%, chick mortality was 35 to 44% by the time of dispersal (Choate 1963).

In Glacier National Park nests are found close to rocks, water, and a good food source; the site is chosen by the female. Populations in the Park appear to be genetically monogamous as well as socially monogamous, with a low incidence of extra-pair paternity (Benson 2002). Clutch size varies from 3 to 9 eggs, averaging about 5 eggs. Most clutches are produced in late June and early July. Renesting is infrequent, with a week delay between attempts, and the clutch size of second nests is smaller than in first attempts. Average annual productivity in Glacier National Park is about 56% (Wright and Conaway 1950, Edwards 1957, Choate 1963, Braun et al. 1993). Generally this species first breeds at 2 to 3 years of age.

No management activity appears necessary at this time. Populations of White-tailed Ptarmigan are largely in protected or remote areas (Choate 1963). No hunting season currently exists and survey and census estimates for most local populations are not available. No change in hunting status is warranted unless adequate field surveys are conducted. Livestock grazing in White-tailed Ptarmigan habitat could have a detrimental effect on the availability of summer and winter foods and should be avoided (Braun et al. 1993).