The Western Capercaillie (Tetrao urogallus), also known as the Eurasian Capercaillie, and the Wood Grouse, is the largest extant grouse species and a member of the grouse family. Found in Europe and the Palearctic, this ground-dwelling forest grouse is known for its courtship display and shows significant sexual dimorphism, with males being nearly twice the size of females.
Males typically weigh 4.1 kg, ranging from 74 to 85 cm in length, while females weigh about half as much and are 54–64 cm long. Males have dark grey to brown feathers with a metallic green breast, while females have brown upper parts with black and silver barring.
Both sexes feature a white spot on their wings and feathered legs for cold protection. Chicks resemble the hens in coloration for camouflage and develop adult plumage around three months old. The eggs are similar in size to chicken eggs but are more speckled.
The capercaillie is a non-migratory bird found in northern Europe and the Palearctic, inhabiting mature conifer forests with diverse species and open canopies. Once widespread in taiga forests, its Scottish population went extinct but has been reintroduced from Sweden. In Germany, it is considered threatened and has disappeared from lower mountainous areas. While it remains common in Norway, Sweden, Finland, and parts of the Alps, it was extirpated in Ireland by the 18th century. Major threats to the capercaillie include habitat degradation from converting diverse forests to single-species plantations and increased predation by smaller predators due to the decline of larger ones.
