# UKBirds

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## Western Capercaillie

### Tetrao urogallus

The Western Capercaillie (Tetrao urogallus), also known as the Wood Grouse, Heather Cock or Capercaillie is the largest member of the grouse family, reaching over 100 cm in length and 6.7 kg in weight. The largest recorded in captivity had a weight of 7.2 kg. (15.9 lbs). Found across Europe and Asia, it is renowned for its mating display.
Male and female Western Capercaillie - the cocks and the hens - can easily be differentiated by their size and colouration. The cock is much bigger than the female. The largest specimen ever recorded in captivity had a weight of 7.2 kg. (15.9 lbs). Cocks can range from 74 to 90 cm (29 to 35 in) in length with wingspan of 87 to 125 cm (34-49 in) and an average weight of over 4 kg (8.8 lb). The body feathers 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 (see below).
The hen is much smaller, weighing about half as much as the cock. The hen's body from beak to tail is approximately 54-64 cm (21-25 in) long, the wingspan is 70 cm (28 in) and weighs 1.5-2.5 kg (3.3-5.5 lbs). Feathers on the upper parts are brown with black and silver barring, on the underside they are more light and buffish-yellow.
Both sexes have a white spot on the wing bow. They have feathered legs, especially in the cold season for protection against cold. Their toe rows of small, elongated horn tacks provide a snowshoe effect that led to the German family name "Rauhfußhühner", literally translated as "rough feet chickens".
These so called "courting tacks" make a clear track in the snow in winter. Both sexes can be distinguished very easily by the size of their footprints.
There is a bright red spot of naked skin above each eye. In German hunters' language, these are the so-called "roses".
The small chicks resemble the hen in their cryptic colouration, which is a passive protection against predators. Additionally, they wear black crown feathers. At an age of about 3 months, in late summer, they moult gradually towards the adult plumage of cocks and hens. The eggs are about the same size and form as chicken eggs, but are more speckled with brown spots.