also ger·fal·con n.

A large falcon (Falco rusticolus) of Arctic regions, having color phases that range from black to gray to white.

[Middle English girfaucoun, from Old French girfaut, gerfaucon : Old High German gīr, vulture + Old French faucon, falcon; see falcon.]

Falco rusticolis

SUBFAMILY

Falconinae

TAXONOMY

Falco rusticolus Linnaeus, 1758, Sweden. Monotypic (no sub-species).

OTHER COMMON NAMES

English: Gyrfalcon; French: Faucon gerfaut; German: Gerfalke; Spanish: Halcón Gerifalte.

PHYSICAL CHARACTERISTICS

Male 18.9–24.0 in (48–61 cm), female 20.1–25.2 in (51–64 cm); male 1.8–2.9 lb (800–1,325 g), female 2.2–4.6 lb (1,000–2,100g). Largest of the falconids and the only white falcon. Highly variable plumage: from nearly pure white through various barred, chevroned, and streaked gray plumages to nearly uniform dark gray-brown. Adults have bright yellow legs and feet. Juveniles tend to be slightly browner and more heavily streaked; pale gray legs and feet. White form usual in high Arctic; dark form in Labrador; gray forms predominate in Iceland; mostly gray individuals grading to equal numbers of white individuals from west to east across Russia and Siberia.

DISTRIBUTION

The most northern of all diurnal raptors. Breeds around the Arctic circle: Iceland, Greenland, North America, and Eurasia; winters farther south.

HABITAT

Fairly uniform habitat: tundra and taiga, from sea level to about 4,600 ft (1,400 m), ice bound and snow covered much of the year. Favors rivers and seacoasts, also mountains. Winter migrant to ice edge, farmland, agricultural land, and steppe.

BEHAVIOR

In populations below 70° north many birds are resident, especially adult males. Migratory above 70° north, moves mainly but not only south to over-winter in warmer areas where prey is plentiful, mostly north of 40° north. Juvenile tracked with satellite transmitter from Alaska to Russia and back.

FEEDING ECOLOGY AND DIET

Hunts mostly ground-dwelling birds and mammals, such as ptarmigan, grouse, ground squirrels, and lemmings. Mostly flies low and fast to surprise and flush prey; occasionally takes birds after pursuit on the wing, and lifts waterfowl and shore-birds from water.

REPRODUCTIVE BIOLOGY

Breeds annually as solitary pairs from March to July. Lays eggs in depression on cliff ledge, large stick nest of another species, or man-made structure. High variation in clutch size and nesting success, depending on prey availability; clutch usually three

or four but up to seven; incubation 33–36 days; fledges at about seven weeks.

CONSERVATION STATUS

Not threatened. Naturally uncommon but can be locally common. Its preference for remote habitat gives it some protection from threats to many other raptors. Fur trappers in Arctic Russia may kill 1,000–2,000 annually, some are taken by egg collectors and falconers.

SIGNIFICANCE TO HUMANS

Prized for falconry, but probably small numbers taken from wild and are now bred in captivity for that purpose.

For more information on gyrfalcon, visit Britannica.com.

The most popular bird for hunting by falconry. A large white to gray bird, very discriminating hunter and kills only while in flight. Called also Falco rusticolus.

Falco rusticolus 20-25″ (50-63 cm). A very large arctic falcon, larger and more robust and buteo-like than the Peregrine; slightly broader-tailed. Wingbeats deceptively slower. More uniformly colored than the Peregrine, with thinner sideburns. In the Arctic there are black, gray, and white forms; these are color morphs, not races.

Similar species: Peregrine is smaller and more contrastingly patterned, with a dark hood and broad black sideburns. It is slimmer with a more tapered tail.

Range: Arctic regions; circumpolar.

Habitat: Arctic barrens, seacoasts, open mountains.

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