The gyrfalcon (/ˈɜːrfɔːlkən/ or /ˈɜːrfælkən/) (Falco rusticolus), the largest of the falcon species, is a bird of prey. The abbreviation gyr is also used.[2] It breeds on Arctic coasts and tundra, and the islands of northern North America and the Eurosiberian region. It is mainly a resident there also, but some gyrfalcons disperse more widely after the breeding season, or in winter. 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. For centuries, the gyrfalcon has been valued as a hunting bird. Typical prey includes the ptarmigan and waterfowl, which it may take in flight; it also takes fish and mammals.

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Falconidae
Genus: Falco
Subgenus: Hierofalco
F. rusticolus
Binomial name
Falco rusticolus
Linnaeus, 1758
  • Falco arcticus Holbøll, 1843
  • Falco candicans Gmelin, 1788
  • Falco gyrfalco Linnaeus, 1758
  • Falco islandus Brünnich, 1764
  • Falco obsoletus Gmelin, 1788
  • Falco rusticolus candicans Gmelin, 1788
  • Falco rusticolus grebnitzkii (Severtzov, 1885)
  • Falco rusticolus intermedius Gloger, 1834
  • Falco rusticolus islandus Brünnich, 1764 (but see text)
  • Falco rusticolus obsoletus Gmelin, 1788
  • Falco rusticolus rusticolus Linnaeus, 1758
  • Falco swarthi L.H. Miller, 1927
  • Hierofalco grebnitzkii Severtzov, 1885)
  • Hierofalco islandus (Brünnich, 1764)
  • Hierofalco rusticolus (Linnaeus, 1758)
  • Hierofalco rusticolus candicans (Gmelin, 1788)