- 18.9–25.2 in
- 48.4 in
- 28.2–74.1 oz
- Faucon gerfaut (French)
- Halcón gerifalte (Spanish)
- The Gyrfalcon eats mostly ptarmigan, but many other prey species have been recorded, including fulmars, gulls, jaegers, ducks, geese, Rough-legged Hawk, Short-eared Owl, sparrows, buntings, and redpolls.
- The female Gyrfalcon regularly stores prey during the breeding season, generally within 100 meters (328 feet) of the nest. Little is known of food-caching outside the breeding season; in one case, a Gyrfalcon was seen retrieving a frozen ptarmigan and chipping off pieces of meat to eat, in mid-winter in the Aleutian Islands.
- Gyrfalcon is pronounced as "JER-falcon." The name probably evolved from Old Norse, but linguists do not completely agree on the specific origin of the word.
- The Gyrfalcon sometimes bathes in runoff water of still-frozen rivers.
Breeds in tundra, often near rivers or coasts. Winter habitat similar; at lower latitudes, open country, especially near water.
Mostly birds, especially ptarmigan. Also consumes mammals, ranging in size from voles to hares.
- Clutch Size
- 1–5 eggs
- Egg Description
- White with variable cinnamon spots; may be mostly brown.
- Condition at Hatching
- Covered with thick down; capable of sitting up and begging shortly after hatching.
Does not build nest; usually uses nests built by other species, including Common Raven and Golden Eagle, usually on cliff ledge.
Male performs spectacular aerial displays with dives and 180° rolls. Uses four methods to pursue prey: 1) flying low and surprising prey on ground; 2) pursuing prey over long distances, forcing it low or high and exhausting it; 3) hovering and making short stoops to force prey out of cover; 4) flying straight up to strike at birds overhead. Strikes prey or drives it to the ground, rather than grasping it in the air; dead prey typically have broken breast bone.
No evidence of long-term population changes in North America. Commercial markets in falconry may pose a threat in Scandinavia and Russia.
- Clum, N. J., and T. J. Cade. 1994. Gyrfalcon (Falco rusticolus). In The Birds of North America, No. 114 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.