Capercaillies are amongst the largest birds of our fauna, as males weigh up to 5 kilograms and are over a meter long, with a wingspan of 120-130 cm. Adult males (cocks) have a slate-gray plumage with blue and green reflections, with the exception of the wings and part of the back that are reddish-brown, while the tips of the belly and undertail feathers are white. The unusual aspect of cocks is increased by a massive curved ivory bill, the conspicuous red wattles over each eye, a white round spot that stands out on the wing bow, the lanceolate feathers of the chin that form a sort of stiff beard, and above all by the long squared tail feathers that spread out into the characteristic large fan whenever capercaillies raise and spread their tail.
The flashy plumage of the males contrasts with the modest camouflaged one of the females (hens) that is characterized by an overall brownish-red color thickly covered with black and white specks on the top and sides. Hens are significantly smaller than cocks: they weigh about half as much and the bill to tail length is about 70 cm. The plumage of young capercaillies resembles the one of an adult female, a little more grayish in males and reddish in females. Feathers moult gradually into adult plumage by the second year of life.
Capercaillies live in forests rich in glades and abundant undergrowth that make the forest vegetation quite varied, both vertically and horizontally. Conifers and forest vegetation provide capercaillies with excellent opportunities for shelter and concealment, and basic nourishment as well: fruit, berries and small invertebrates during summer and autumn; buds and shoots in spring.