Closest to F. cherrug; genetic data indicate that these two, along with F. biarmicus and F. jugger, form a group of closely related species#R. Has hybridized with F. peregrinus#R. Taxonomy complicated. Usually considered monotypic, but highly polymorphic, and this is partially responsible for considerable discussion as to species’ valid name, with F. rusticolus in general usage (selected by First Reviser) and recently defended against F. gyrfalco, which is frequently used in Russian literature#R; others maintain that F. rusticolus is an invalid name for F. peregrinus, and that either F. gyrfalco or even F. canadensis should be used for present species#R. Sometimes regarded as polytypic, normally with four races (rarely, up to seven#R), based mainly on colour frequencies: rusticolus (Europe); obsoletus (Asia, parts of North America); candicans (high Arctic of North America, Greenland); and islandus (Iceland), the most isolated, uniform and distinctive of these forms, which would probably be most valid race. Described form altaicus of F. cherrug has been listed as race of present species (see F. cherrug). Monotypic.
Circumpolar, occupying Arctic regions of Eurasia, North America, Greenland and Iceland; some birds move farther S for winter.
48–60 cm; male 769–1450 g, female 1130–2150#R g; wingspan 105–135 cm#R. The largest Falco, with larger head, deeper chest, relatively short but broad outer wings and longer tail than other large falcons#R. Extreme polymorphism in coloration, with three main colours, white, grey and blackish brown. Streaked or barred on underparts; white birds with some dark markings on upperparts and underparts. Legs and feet yellow, but extremely long and dense thigh feathers often completely cover them#R. Female larger (7–25%) and heavier (8–160%)#R, sometimes darker. Juvenile generally darker, browner and more heavily streaked below; legs and feet pale grey. Other than white morph birds, F. rusticolus is most similar to F. cherrug, but latter almost wholly allopatric. Some female F. peregrinus of northernmost races appear almost as bulky, but shorter tailed, narrower and more pointed winged, with uniformly dark-barred underwings#R. In Nearctic, confusion also possible in winter with F. mexicanus, but latter is smaller and paler, and has different head and underwing patterns#R. The three main colour morphs vary and grade into one another, sometimes along clines, or at any rate with colour morph ratios differing regionally: birds in high Arctic of Greenland usually white; in Labrador, preponderance is dark brown or even blackish; in Iceland, normally various shades of grey; clinal W to E across Russia and Siberia, with 90% grey drifting into 47% white; also slight variation in size, with larger birds in N of range.
Food and feeding
Mainly birds and to lesser extent#R mammals up to size of hares#R. Frequently a major reliance on ptarmigan/grouse (Lagopus) and ground squirrels (Spermophilus) for breeding, but regularly takes birds as small as finches#R; in coastal areas, seabirds may be major food; lemmings (Lemmus, Dicrostonyx) can be mainstay in some areas depending on season. During winter food may be more restricted, where species resident, but more varied for those migrating S, where prey as large as Sage Grouse (Centrocercus) is killed#R. Most hunting by fast flight low over ground, often rising to make rapid stoop; sometimes forages by flying along high up (150–300 m above ground)#R, or perches to scan. Prey taken on ground or water more often than in air, but sometimes after hot pursuit.
Mar–Jul, but territories may be held all winter so breeding essentially starts Jan–Feb. Solitary. Eggs laid in unlined scrape or depression in cliff ledge, disused stick nest of another species on cliff (usually either Common Raven Corvus corax, Golden Eagle Aquila chrysaetos or Rough-legged Buzzard Buteo lagopus)#R, or occasionally stick nest in tree or on man-made structure, e.g. gold dredger or oil pipeline. Usually 3–4 pale buffish or yellowish-white eggs finely spotted red or reddish brown#R (2–7 in years of food extremes) laid at c. 3-day intervals, size 58·9 mm × 45·9 mm#R; incubation 28–36 days, begins with first egg, usually by female alone#R; chicks have creamy-white first down, second longer, coarser and greyish white#R; fledging 46–53 days, with young fed by female, provisioned by male#R. Nest success varies dramatically in response to cyclical food sources: 1·3–4·0 young per successful nest, but generally c. 2·5–3·1 over many years; occupation of c. 31–88% of total territories available; 38–73% of occupied territories produce young. In CW Greenland, where multiple colour variants present, white males fathered signiﬁcantly earlier clutches than grey males (no signiﬁcant association between female colour and laying date), white adults (both sexes) produced signiﬁcantly more offspring than did grey ones, and silver adults (both sexes) produced intermediate number of young; also, grey females paired with grey males nested signiﬁcantly later in season and produced fewer young than females with white mates, whereas no difference in laying date or offspring number between white males paired with white females and those paired with grey females; further, number of offspring produced at each nest-site was inversely correlated with distance to nest of nearest neighbour, grey males nesting closer to other nests than did white and silver variants#R. Although territory fidelty is high, in Alaska birds frequently change nest-site (with mean distance between alternate sites 750 m), and mean tenure of a territory is 2·8 years#R. Home range at this season much smaller than in winter (see Movements), between 140 and 1197 km2#R. Usually first breeds in second or third year; in Iceland, some breed by end of first year. Young have been recorded breeding up to c. 250 km from their natal area#R. Oldest wild birds c. 13 years old.
Many adults sedentary, especially in Iceland and Scandinavia#R; juveniles generally more dispersive and move farthest S. Patterns complicated by cyclical food availability, which may cause irruptive movements, but some very clear movements, e.g. white morph birds from Greenland to Iceland. Some move from North America to Siberia (see Family Text). At least some birds recently confirmed to#R winter around edge of sea ice or near open water (polynyas), presumably feeding on seabirds and resting on icebergs#R. Distances moved in winter exceptionally 3400 km (from Alaska to Arctic Russia)#R, and 4234 km from NW to S Greenland#R. Winter home range huge, e.g. 26,810–63,647 km2 in E Greenland, and one young female moved 4548 km over c. 200-day period#R. Most birds winter N of 52° N and some in low Arctic may scarcely move from their breeding sites#R; in North America has reached S to 35° N (Oklahoma)#R, in Eurasia c. 46° N (Iberia and Italy)#R. Occasionally recorded in summer as far S as British Isles#R.
Status and conservation
Not globally threatened (Least Concern). CITES I. Widespread; rare in some regions, locally common in others but status confounded by cyclical nature of numbers. Densities vary regionally with rather wide ranging estimates of total population from c. 5000–7000 to 15,000–17,000 pairs. Some estimates are: Alaska (USA) 375–635 pairs; Yukon Territory (Canada) 750 pairs; Northwest Territories (Canada) 1300 pairs; Greenland c. 750 pairs; Iceland c. 350 pairs; Scandinavia c. 120–150 pairs; 50 pairs in European Russia, with only 10–15 pairs over area of 14,000 km2 in extreme NE; no survey results for Siberia. Not affected by organochlorines during 1960s and 1970s, as were other Falco. Surveys of a locality in C Canadian Arctic in 1982–91 revealed stable population there#R. Recent mortality at hands of trappers in Siberia (e.g. Yakutsk, Indigirka R) suggests that c. 1000–2000 killed annually throughout Arctic Russia. Highly prized in falconry, with unknown number taken annually; probably not enough to affect breeding population. Now bred in captivity for falconry and research in North America, Europe and Russia.
Comments on the status of revived old names for some North American birds. Auk 112(3): 633–648.
Selection of Nest Sites by Gyrfalcons (Falco rusticolus). MSc thesis, University of British Columbia, Vancouver.
Athuganir a varphattum falka (Falco rusticolus) i Myvatnssveit 1960-1969. Natturufraeoingnum 42: 67-74.
Nesting Behavior and Hunting Activities of the Gyrfalcon (Falco rusticolus) in South Central Alaska. MSc thesis, University of Alaska, Fairbanks.
Nest-site fidelty and dispersal of Gyrfalcons estimated by noninvasive genetic sampling.Condor
The Birds of Japan. Christopher Helm, London.
Seasonal movements of Gyrfalcons Falco rusticolus include extensive periods at sea.Ibis
Biology of the Peregrine and Gyrfalcon in Greenland.Medd. Grønland
Ecology of the Peregrine and Gyrfalcon populations in Alaska. Univ. Calif. Publ. (Zool.) 63: 151-290.
Raptor predation on Rock Ptarmigan (Lagopus mutus) in the central Canadian Arctic.J. Raptor Res.
The Birds of the Western Palearctic. Vol. 2. Hawks to Bustards. Oxford University Press, Oxford.
The Birds of the Soviet Union. Vol. 1. (English translation 1966). Israel Program for Scientific Translations, Jerusalem.
On the biology of the Norwegian Gyrfalcon. Ibis 87: 559-565.
Der Gerfalke. Neue Brehm Bucherei. A. Ziemsen Verlag, Wittenberg Lutherstadt.
Wintering Gyrfalcon Falco rusticolus habitat utilization in Washington. Pp. 61-70 in: Meyburg & Chancellor (1989).
Distribution and color variation of Gyrfalcons in Russia.Journal of Raptor Research
Birds observed in the central Bering Sea pack ice in February and March 1983.Gerfaut
Raptors of the World. Christopher Helm, London.
Raptors of the World.
Christopher Helm, London.
Observations on Gyr Falcon Falco rusticolus in North-east Greenland.Dan. Orn. Foren. Tidssk.
The legal situation of birds of prey in the former USSR. In: Meyburg & Chancellor (1994a).
A Field Guide to the Birds of the USSR. Princeton University Press, Princeton, New Jersey.
Identification forum: large falcons. Birding World 5(3): 101–106.
Observations of wintering Gyrfalcons (Falco rusticolus) hunting Sage Grouse (Centrocercus urophasianus) in Wyoming and Montana, USA.J. Raptor Res.
Collins Photo Guide to the Birds of Prey of Britain and Europe, North Africa and the Middle East. Collins, London.
Gyrfalcon in Oklahoma City: southernmost record for North America.Bull. Okla. Orn. Soc.
Bird Nests, Eggs and Nestlings of Britain and Europe with North Africa and the Middle East.
Second revised edn. HarperCollins, London.
Hawks, Eagles & Falcons of North America. Biology and Natural History. Smithsonian Institution Press, Washington & London.
On the nesting of the Gyr Falcon (Falco rusticolus intermedius Gloger, 1834) in the southern part of the Yamal Peninsula. Bull. MOIP (Biol.) 86: 42-51.
On the biology of the Gyrfalcon on the Kola Peninsula. Proc. Mosc. State Univ. 197: 61-74.
Birds of Russia. HarperCollins, London.
On the breeding ecology of the Gyrfalcon Falco rusticolus in central Norway 1968-1974.Fauna Norvegica (Ser. C, Cinclus)
Characteristics and relative occurrence of remnants of prey found at nesting places of Gyrfalcons Falco rusticolus.Ornis Scand.
Ovanliga bytesdjur funna i bon av jaktfalk Falco rusticolus och pilgrimsfalk Falco peregrinus.Vår Fågelvärld
Fluctuations of observed breeding Rough-legged Hawks and Gyrfalcons: regularity reconsidered.Oecologia
A survey of the breeding falcons of Eqalungmiut Naunaat, West Greenland.J. Raptor Res.
The Yukon Territory Gyrfalcon harvest experiment (1974-80). Pp. 263-280 in: Ladd, W.N & Schempf, P.F. eds. (1982). Proceedings of a Symposium: Raptor Management and Biology in Alaska and Western Canada. FWS/AK/PROC-82.
Long term trends in the breeding density and productivity of Gyrfalcon Falco rusticolus in the Yukon Territory, Canada. In: Meyburg & Chancellor (1994a).
Food of Gyrfalcons at a nest on Ellesmere Island.Wilson Bull.
Annual cycle of the Gyrfalcon in Iceland. Natl. Geogr. Res. 6: 41-62.
Seasonal changes in food habits of Gyrfalcons in NE Iceland.Ornis Scand.
Population fluctuations of Gyrfalcons and Rock Ptarmigan: analysis of export figures from Iceland.Oecologia
Population Ecology of the Gyrfalcon in Iceland, with Comparative Notes on the Merlin and the Raven. PhD thesis, Cornell University, Ithaca, New York.
Kynproskaaldur og atthagatryggo falka. Natturufraeoingurinn 60: 135-143.
Out of Africa? Phylogenetic relationships between Falco biarmicus and the other hierofalcons (Aves: Falconidae).Journal of Zoological Systematics and Evolutionary Research
Handbook of North American Birds. Vols. 4–5. Diurnal Raptors. Yale University Press, New Haven & London.
Commentary - CITES classification of the Gyrfalcon.J. Raptor Res.
Sharp-shinned Hawk nesting and nest site selection in Utah.Condor
The Breeeding Behaviour of Wild and Captive Gyrfalcon in Relation to their Environment and Human Disturbance. PhD thesis, Cornell University.
Gyrfalcon courtship and early breeding behavior on the Yukon North Slope. Sociobiology 15: 43-69.
Gyrfalcon in Oklahoma. Bull. Oklahoma Orn. Soc. 10: 27-28.
Ecology of Gyrfalcons, Falco rusticolus, in the central Canadian Arctic: diet and feeding behavior.Can. J. Zool.
Natural history of the Gyrfalcon in the Central Canadian Arctic.Arctic
T. & A.D. Poyser, London.
The Gyrfalcon. T. & A.D. Poyser, London.
The Birds of Central Siberia. Husum-Druck und Verlagsgesellschaft, Husum, Germany.
Summer Distribution, Numbers and Food Habits of the Gyrfalcon (Falco rusticolus) on the Seward Peninsula, Alaska. MSc thesis, University, Fairbanks, Alaska.
The Ecology of Wintering Gyrfalcons (Falco rusticolus) in Central South Dakota. MSc thesis, Boise State University, Idaho.
Routes and timing of migration of falcons banded in Canada.Wilson Bull.
Chromosome study of Peregrine, Prairie, and Gyrfalcons with implications for hybrids.J. Heredity
Status of the Gyrfalcon Falco rusticolus population in the Northwest Territories, Canada. In: Meyburg & Chancellor (1994a).
Increase in breeding population of Tundra Peregrine Falcons in the central Canadian Arctic.Wilson Bulletin
Sexual Size Dimorphism in Hawks and Owls of North America. Ornithological Monograph 30. American Ornithologists' Union.
Distribution, abundance, and notes on the breeding biology of Gyrfalcons Falco rusticolus in Alaska. In: Meyburg & Chancellor (1994a).
Kunstige reirplasser for jaktfalk Falco rusticolus og vanderfalk Falco peregrinus. Var Fuglefauna 1: 124-151.
A time-lapse nest study of a pair of Gyrfalcons Falco rusticolus from their arrival at the nesting ledge to the completion of egg-laying.Fauna Norvegica (Ser. C, Cinclus)
Systematic notes on Palearctic birds. No. 44, Falconidae: the genus Falco (Part I, Falco peregrinus and Falco pelegrinoides).Amer. Mus. Novit.
Cliff-nesting raptors and Ravens along the Colville River in Arctic Alaska.Living Bird
Hunting range and strategies in a tundra breeding Peregrine and Gyrfalcon observed from a helicopter.J. Raptor Res.
Hunting methods of Gyrfalcons and behavior of their prey (ptarmigan).Condor