Willow ptarmigan 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. The red grouse is common on heather-clad moorland across the north and west of Great Britain and in localised areas of Ireland. The willow ptarmigan has a varied and seasonal diet. The bird is herbivorous for most of its life and subsists on various plant materials. As juveniles, they may feed on insects due to an inability to
Rock ptarmigan the Russian High Arctic overwinters during the polar night and survives by feeding on rich vegetation on and underneath high cliffs where seabird colonies are located in summer.<ref name="FJL/">Dinets, V. (2001) Winter ecology of Willow Ptarmigan "Lagopus lagopus" and Rock Ptarmigan "L. mutus" at the northern limit of their range. "Ornitologia" 29: 326-327 (in Russian with English summary).</ref> During the last ice age, the species was far more widespread in continental Europe. The rock ptarmigan feeds primarily on birch and willow buds and catkins when available. It also eats various seeds, leaves, flowers, and berries of other plant species. Insects