It has some white spots scattered over the rounded tail feathers. The beak is white with red skin above and behind the eyes. The throat feathers are ruffled and form a small beard. There is a small white area on the edge of the wing. The female has a reddish brown livery barred with black. A large reddish stain marks the chest. The tail is long and reddish non-indented unlike that of the female of black grouse.
Its usual habitat is of the taiga forests, coniferous and mixed forests. It is not generally found in spruced areas because it needs a habitat with mixed aged trees and clearings with blueberries and mountain ash.
It will perch in trees, walking even on the small branches. Usually shy and cautious, it is easier to spot in the Spring when the males strut. The courtship is spectacular and takes place in a specific place prepared for this purpose called "lek" or "singing place" as a result of the strange, guttural cries of the males.
The nest is a hollow in the ground lined with grass and leaves. In June-July, the female lays 5 to 9 eggs. The chicks hatch after four weeks of incubation, their lower body being pale yellow, with a darker back, with beige, brown, and black bands.
Capercaillie occasionally hybridise with Black Grouse and even Ring-necked Pheasant if breeding numbers are few.
The Capercaillie has a mixed but predominantly vegetarian diet. It eats pine needles, buds, leaves, berries, but also ants and beetles. Besides that, it frequently eats gravel that aids digestion, quite common behaviour in many seed-eating bird species.
The Capercaillie is mainly threatened by the change of habitat and illegal hunting. They also suffer from disturbance during the breeding season due to the creation of ski trails and forest work.