(Falco rusticolus), Arctic bird of prey of the family Falconidae, the world's largest falcon (q.v.). The gyrfalcon may reach 60 cm (2 feet) in length. Confined as a breeder to the circumpolar region except for isolated populations in Central Asian highlands, it is sometimes seen at lower latitudes in winters when food is scarce. The gyrfalcon varies from pure white with black speckling to dark gray with barring. The legs are fully feathered.

The gyrfalcon hunts near the ground for hares, rodents, and birds of the tundra and seacoast. Its only rival is the higher flying peregrine falcon. In traditional falconry, the gyrfalcon was the bird of kings. The gyrfalcon is now the official mascot of the U.S. Air Force Academy.