The Western Capercaillie (Tetrao urogallus) is the largest member of the grouse family.
The male and female birds can easily be differentiated by their size and colouration. The male bird is much bigger than the female. The body feathers of the cocks are coloured dark grey to dark brown, while the breast feathers are dark metallic green. The belly and undertail coverts vary from black to white depending on race.
The hen weighs about half as much as the cock. Feathers on the upper parts are brown with black and silver barring on the underside they are more light and yellow.