The Gyrfalcon, Falco rusticolus, is a large bird of prey. This species breeds on arctic coasts and islands of North America, Europe and Asia. It is mainly resident, but some birds disperse more widely, after the breeding season, or in winter.
It is a bird of tundra and mountains, with cliffs or a few patches of trees. It lays 2-6 eggs on a cliff ledge nest.
This is the largest falcon, with a wingspan similar to Common Buzzard. It is like a large Peregrine Falcon in general structure, but broader-winged and longer-tailed than that species. It usually hunts by horizontal pursuit, rather than the Peregrine's stoop from a height, and takes bird and mammal prey such as Ptarmigan and lemmings.
Plumage is very variable in this species, although typically adults have slate-grey back and wings, and young birds are browner. Sexes are similar. Greenland Gyrfalcons have white plumage, flecked with grey on the back and wings. Other geographical forms are varying intensities of grey in coloration, with Icelandic breeders being the palest, and Eurasian birds considerably darker.