The gyrfalcon or Falco rusticolus, also spelled gerfalcon, is the largest of all falcon species. The Gyrfalcon breeds on Arctic coasts and islands of North America, Europe and Asia. It is mainly resident, but some Gyrfalcons disperse more widely after the breeding season, or in winter.
The bird’s common name comes from French gerfaucon, and in mediaeval Latin is rendered as gyrofalco. The first part of the word may come from Old High German gîr (cf. modern German Geier), “vulture”, referring to its size compared to other falcons, or the Latin gȳrus (“circle”, “curved path”) from the species’ circling as it searches for prey, unlike the other falcons in its range. The male gyrfalcon is called a gyrkin in falconry.
Its scientific name is composed of the Latin terms for a falcon, Falco, and for someone who lives in the countryside, rusticolus.