The most common eastern American grouse is the ruffed grouse (sometimes miscalled partridge or pheasant), Bonasa umbellus, a forest bird noted for the drumming sound made by the male during its elaborate courtship dance. The ptarmigan (Lagopus lagopus), or snow grouse, is an arctic species that migrates to the NW United States in winter, when its plumage changes from rusty brown to white, matching the snow. Western American grouse include the prairie chicken, Tympanuchus cupido, once common in the East, and the sage grouse, Centrocercus urophasianus. The latter, called also sage hen, sage cock, or cock of the plains, is the largest American grouse (25-30 in./62.5-70 cm long) and so named because its flesh tastes strongly of sage—the result of feeding on sagebrush buds. The males of both these species are distinguished by yellow air sacs on the neck that inflate to an enormous size during courtship. European species include the capercaillie, the largest grouse (roughly the size of turkey), and the black grouse. The red grouse is found in Great Britain.
Striking fluctuations in the abundance of all grouse species occur in intervals of 7 to 10 years. A combination of factors, rather than a single explanation, appears to be the cause for this not entirely understood phenomenon. Fortunately, grouse have high reproductive rates, which enable them to restore their populations after a low-level period.
Grouse are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Galliformes, family Tetraonidae.
Grouse are a group of birds from the order Galliformes. Often considered a family Tetraonidae, the American Ornithologists' Union and many others include grouse as a subfamily Tetraoninae in the family Phasianidae. Grouse inhabit temperate and subarctic regions of the northern hemisphere, from pine forests to moorland and mountainside. Most species are year-round residents, and do not migrate.
These birds feed mainly on vegetation, but also on insects, especially when feeding young. Several of the forest-living species are notable for eating large quantities of conifer needles, which most other vertebrates refuse. In all but one species (the Willow Grouse, called Willow Ptarmigan in America), males are polygamous, and many species have elaborate courtship displays. These heavily built birds have legs feathered to the toes.
Genus Lagopus - ptarmigans
Genus Tetrao - black grouse
Genus Centrocercus - sage-grouse
Genus Tympanuchus - prairie grouse