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(Lagopus lagopus), a bird of the family Tetraonidae, order Galliformes. The body length is 35–38 cm, and the weight, 400–870 g. The feet are feathered down to the claws. In the winter the plumage is white, and in the summer it is yellowish or rusty-brown. The females molt three times a year; the males, four. The seasonal coloring change of the willow grouse is a good example of protective coloration in birds.
The willow grouse is found in northern Europe, Asia, and North America; it lives in tundra and mossy swamps of the forest zone and in birch and aspen groves in the forest-steppe of Western Siberia and Kazakhstan. Willow grouse are also found in the shrubs of the subalpine mountain zone. There are eight to 12 eggs in a clutch, and the female incubates the eggs for 18 to 20 days. Both parents remain for the rearing. They feed primarily on vegetation—in the winter, on buds and shoots, especially of willow and birch, and in the summer, on leaves and berries. In northern regions, especially in the forest tundra to which they migrate in the winter from the tundra, willow grouse are an important object of commercial hunting. The number of grouse in the forest and forest-tundra zones is dwindling in connection with the draining of swamps.