Grouse, common name for 17 species of birds of the pheasant family, found around the world in the northern hemisphere; two of the three species of ptarmigan inhabit both the Americas and Eurasia. Grouse vary in size from males of the capercaillie, 86 cm (34 in) long, of European coniferous forests, to the 32 cm (12.5 in) white-tailed ptarmigan, of western North American mountains. In most species the sexes differ in color, but none have truly bright plumage. Bright colors are limited to red or yellow comblike structures over the eyes, expanded during the breeding season, or sacs of naked skin that inflate like balloons during courtship displays. Mating systems are elaborate in most grouse, and in many the males are polygamous, meeting in the spring at certain arenas where they compete for mates.

As highly popular game birds, grouse have been intensively studied. Best known and most widely distributed of the American species is the ruffed grouse, which occurs in woodlands from Alaska to Newfoundland and Labrador, south to the northern Rocky Mountains and the Appalachians. The name comes from a ruff of black (rarely, coppery) feathers at the sides of the neck. These feathers are larger in males than in females, and are spread widely during courtship displays, when the male struts on a moss-covered log. This species is famous for the springtime “drumming” of the males, a sound produced by the beating of the wings against the air as the male stands erect. The sound carries a great distance, and resembles a noisy gasoline engine starting up.

Two other North American grouse, the blue grouse of western mountains and the more widely-distributed spruce grouse are confined to coniferous forests. The male blue grouse has inflatable neck sacs, varying geographically in color from yellow to reddish purple; the spruce grouse lacks such sacs. These two species have been called “fool hens” because of their apparent fearlessness, making them easy to hunt.

Two species of prairie chicken, the closely related sharp-tailed grouse, and the sage grouse, dwell in open country. The latter, an inhabitant of sagebrush areas, especially in the Great Basin, is the largest American grouse. Males reach 75 cm (30 in) in length; females are smaller (58 cm/23 in). During the communal courtship displays, males strut about with their spiky tail feathers fanned out, and a pair of yellow sacs on their chests inflated.

Scientific classification: Grouse belong to the family Phasianidae of the order Galliformes. The capercaillie is classified as Tetrao urogallus, the white-tailed ptarmigan as Lagopus leucurus, and the ruffed grouse as Bonasa umbellus. The blue grouse is classified as Dendragapus obscurus and the spruce grouse as Dendragapus canadensis. Prairie chickens are classified in the genus Tympanuchus. The sharp-tailed grouse is classified as Tympanuchus phasianellus and the sage grouse as Centrocercus urophasianus.