Gyrfalcon

The gyrfalcon, also abbreviated as gyr, is a bird of prey in the genus Falco and the largest species of the family Falconidae. A high-latitude species, the gyrfalcon breeds on the Arctic coasts and tundra, the islands of northern North America and Siberia, where it is mainly a resident species. Some gyrfalcons disperse more widely after the breeding season or in winter, and individual vagrancy can take birds for long distances. Its plumage varies with location, with birds being coloured from all-white to dark brown. These colour variations are called morphs. Like other falcons, it shows sexual dimorphism, with the female much larger than the male.

Source: Wikipedia