Grouse are a group of birds from the order Galliformes. They are sometimes considered a family Tetraonidae, though 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,
from 83° North (Rock Ptarmigan in northern Greenland) to 28° North (Attwater's Prairie Chicken in Texas).

Grouse are heavily built. They range in length from 31 cm (12 in) to 95 cm (37 in), in weight from 0.3 kg (11 oz) to 6.5 kg (14 lb). Males are bigger than females—twice as heavy in the Capercaillie, the biggest member of the family.
Grouse have feathered nostrils. Their legs are feathered to the toes, and in winter the toes too have feathers or small scales
on the sides, an adaptation for walking on snow and burrowing into it for shelter. Unlike other Galliformes, they have no spurs.

These birds feed mainly on vegetation—buds, catkins, leaves, and twigs—which typically accounts for over 95 percent of
adults' food by weight. Thus their diet varies greatly with the seasons. Hatchlings eat mostly insects and other invertebrates,
gradually reducing their proportion of animal food to adult levels. Several of the forest-living species are notable for eating
large quantities of conifer needles, which most other vertebrates refuse.

Forest species flock only in autumn and winter, though individuals tolerate each other when they meet. Prairie species are more social, and tundra species (ptarmigans, Lagopus) are the most social, forming flocks of up to 100 in winter. All grouse spend
most of their time on the ground, though when alarmed, they may take off in a flurry and go into a long glide.
Source: http://en.wikipedia.org/wiki/Grouse

Genus Falcipennis
Siberian Grouse, Falcipennis falcipennis
Spruce Grouse, Falcipennis canadensis
Franklin's Grouse, Falcipennis canadensis franklinii

Genus Dendragapus
Dusky Grouse, Dendragapus obscurus
Sooty Grouse, Dendragapus fuliginosus

Genus Lagopus - ptarmigans
Willow Ptarmigan, Lagopus lagopus
Red Grouse, Lagopus (lagopus) scoticus
Rock Ptarmigan, Lagopus muta (mutus) No: Fjellrype
White-tailed Ptarmigan, Lagopus leucura

Genus Tetrao - black grouse
Black Grouse - Eurasian Black Grouse, Tetrao tetrix, No: Orrfugl
Caucasian Grouse - Caucasian Black Grouse, Tetrao mlokosiewiczi, No: Kaukasusorrfugl
Western Capercaillie - Eurasian Capercaillie, Tetrao urogallus, No: Storfugl (Tiur)
Black-billed Capercaillie, Tetrao parvirostris, No: Svartnebbstorfugl

Genus Tetrastes
Hazel Grouse, Tetrastes bonasia
Chinese Grouse, Tetrastes sewerzowi

Genus Bonasa
Ruffed Grouse, Bonasa umbellus

Genus Centrocercus - sage grouse
Sage Grouse, Centrocercus urophasianus
Gunnison Grouse, Centrocercus minimus

Genus Tympanuchus - prairie grouse
Sharp-tailed Grouse, Tympanuchus phasianellus
Columbian Sharp-tailed Grouse, T. phasianellus columbianus
Greater Prairie Chicken, Tympanuchus cupido
Attwater's Prairie Chicken, Tympanuchus cupido attwateri
Heath Hen, Tympanuchus cupido cupido (extinct, 1932)
Lesser Prairie Chicken Tympanuchus pallidicinctus