The willow ptarmigan breeds in birch and other forests and moorlands in northern Europe, the tundra of Scandinavia, Siberia, Alaska and Canada, in particular in the provinces of Newfoundland and Labrador and Quebec.

In the summer, the male's plumage is marbled brown, with a reddish hue to the neck and breast, a black tail and white wings and underparts.

[3] The white-tailed ptarmigan (Lagopus leucura) in North America is smaller, has a white tail and finely-barred greyer plumage and lives permanently above the tree line.

Pleistocene willow ptarmigan are recorded from diverse sites until the end of the Vistulian glaciation about 10,000 years ago, when the species, by then all but identical with the living birds, retreated northwards with its tundra habitat.

[1] It primarily occupies subalpine and subarctic habitats such as sparse pine and birch forests, thickets with willow and alder trees, heather moors, tundra and mountain slopes.

In the winter, females and sub-adults may move to lower altitudes and seek shelter in valleys or in more densely vegetated areas, but adult males usually remain in the subalpine region.

[19] In the early twenty-first century, there has been an increase in shrub expansion in arctic Alaska that is thought to be greatly affecting the willow ptarmigan's winter diet.

[19] After heavy snowfalls, the birds cannot access the shorter shrubs as they are blanketed with snow, so they will eat the taller species that poke through.

However, in winters with below average snowfall, the browsing of ptarmigans will not have such a drastic effect as their feeding will be spread out across a range of lower plant species.

It is also believed that the greening of parts of the Arctic is affecting willow ptarmigan populations by altering the shape and size of the shrubs they are able to feed on.

[4] In most other species of grouse, only the female takes care of the young, but the male willow ptarmigan also helps with feeding the brood and protecting them.

Nevertheless, the chicks face many dangers which range from attacks by foxes or birds of prey, to getting separated from the rest of the brood, bad weather, and coccidiosis.

The females and young migrate to lower altitudes and may overwinter 100 miles (160 km) from their breeding grounds in wooded valleys and hilly country.

[4] The willow ptarmigan has several behavioral and physiological adaptations that help it survive the long Arctic winter, such as large pectoral muscles that aid in the process of shivering.

[21] Ptarmigan also have thick plumage with feather barbules that contain air-filled cavities,[22] contributing to a low heat loss, which aids in thermoregulation while the bird is roosting in burrows in the snow.

This is because, even if, as is suspected, numbers are declining slightly, it has a very wide range with a total population estimated at forty million individuals.