The consummate falcon of the Arctic region - the Gyrfalcon - is a bird that stirred the imagination of Kublai Khan and was written about by Marco Polo. It is a large and powerful falcon with plumage that varies from nearly pure white through very dark sepia and tones of streaked gray in between. The Gyrfalcon lacks the large mustache of the Peregrine Falcon, and the two-toned underwing of the gray-phase birds distinguish them from other larger falcons. The white birds are unlike any other. The flight is fast and powerful.
Nesting is on cliffs in the northern latitudes, with most birds spending the entire year close to the breeding grounds. Post-breeding dispersal brings some birds as far south as the northern United States every year, providing excitement and anticipation amongst birdwatchers anxious to see the "big northern Gyrfalcon!"
SIZE
The Gyrfalcon is the largest of the North American falcons. The females vary from 20.5 to 25.5 inches (52.1 to 64.8 centimeters) with an average of 22 inches (55.9 centimeters) in length, and wingspreads from 47 to 53 inches (119.4 to 134.6 centimeters). Their weights vary from 2.5 to 4.4 pounds (1134 to 1996 grams). Males are slightly shorter at 19 to 22.5 inches (48.3 to 57.2 centimeters) with an average of 21 inches (53.3 centimeters), and wingspreads from 40 to 49 inches (101.6 to 124.5 centimeters). They weigh between 1.75 and 2.9 pounds (794 to 1,315 grams). Weight ranges of live birds captured in the wild can vary depending upon breeding condition, time of year, and whether prey has been recently captured and is still in the crop. In one study, live captured migrants in Greenland did not exhibit such a wide weight variation with females averaging 3.2 pounds (1,451 grams) and males 2.8 pounds (1,270 grams).
MORPHS AND MOLTS
The Gyrfalcon ranges in color from pure white birds with darker spots, through degrees of gray to an extreme of very dark brown. This has led many authors to describe three morphs, or color phases, as white, gray, and dark or black. Others disagree with such divisions and suggest that color variation is a continuum from white to dark with much variation between. The specific descriptions follow this latter philosophy, but for ease of organization it will arbitrarily deal with white, gray, and dark groupings of plumages. Sexes are generally alike but males can be lighter overall than females, especially in gray phase birds. Often in males, the saturation of dark pigments is not as great as in females but this is not universally true.
Molting occurs annually, and following the juvenile plumage, birds reach adult plumage after the first molt (2nd calendar year of life). Appearance does not change with subsequent molts. Molt in the adults begins while the young are still in the nest but the ability to fly is never lost. Wings and tail begin to molt first, followed by body feathers, with the entire process lasting about five months (in captive birds). Molt from the juvenile into adult feathering starts with the body feathers during the first winter. The wings and tail feathers start at the same time as the adults, which is in the April to May period.
SPECIFIC DESCRIPTION
Adult Gray-morph - Perched
Note that this color phase includes a spectrum of plumages ranging from gray through brown except for the darkest of birds.
HEAD
- variably gray on the crown, sides and nape with light whitish steaks
- usually white across the forehead, on the chin, and in superciliary area above the eye
- some birds may have a narrow dark mustache mark extending down from the eye
- there is often a dark area behind the eye and the cheek is pale with variable dark markings
- the beak is bluish basally with a dark tip
- the cere is yellow and eyelids pale flesh
- the eye is dark
BODY
- the underparts are white with dark streaks on the breast and variable dark barring on the sides and belly
- the white may be washed with cream or buff tones
- the back varies from slate gray with or without a sepia tinge and these feathers have variably light margins and pale gray cross bars
WINGS
- as for the back with a slate gray color and pale gray cross bars on the primaries and scapulars
- the primaries have long, unbarred dark tip areas
TAIL
- banded with alternating light and dark gray bands on the dorsal surface, but usually white beneath
LEGS
- the legs and feet are yellow and the talons black
Immature Gray-morph - Perched
HEAD
- dark, gray-brown crown and nape with pale streaking
- usually white across the forehead, on the chin and in superciliary area above the eye
- some birds may have a narrow dark mustache mark extending down from the eye
- there is often a dark area behind the eye and the cheek is pale with variable dark markings
- beak bluish horn with a darker tip
- cere and eyelids bluish gray
- the eye is dark
BODY
- underparts are creamy-white with heavy dark-brown vertical streaking
- the back is grayish-brown and more brown than the adults
WINGS
- upper wing coverts are colored similarly to the back
- the primaries are extensively dark tipped
TAIL
- dark brown with numerous narrow, light bands that vary in width between individuals
LEGS
- the legs and feet are bluish to greenish gray and the talons black
Adult Dark-morph - Perched
HEAD
- overall may be dark sepia and appear "hooded" with some light marks on the nape
- beak bluish basally with dark area at the tip
- cere yellow and eyelids flesh
- eye dark
BODY
- the underparts can be almost entirely dark or appear streaked with light areas on the breast and cross-barred with light areas on the lower belly and flanks
- the back is sooty-brown
WINGS
- sooty brown coverts and primaries
TAIL
- upper tail coverts and tail are dark, sooty brown with many light transverse bands
- some individual tails may be all dark with dark barring and a pale brown tip
- undertail dark with light markings
LEGS
- the tarsi and feet are yellow and the talons are black
Immature Dark-morph - Perched
HEAD
- solid dark brown with occasional light marks on the hind neck and crown
- beak and cere as in adults
- eye dark
BODY
- underparts are dark brown with some white streaking but variable
- back is dark brown
WINGS
- the upperwing coverts and primaries are dark brown
TAIL
- the tail is solid dark brown but occasionally the top may show light barring
- the undertail coverts are dark brown with paler barring
LEGS
- the tarsi and feet are bluish gray and the talons dark brown-black
Adult White-morph - Perched
HEAD
- virtually entirely white in the lightest birds
- variable amounts of dark brown/black streaking on the crown extending into spots on the nape.
- throat white
- beak variously described as yellowish -brown to yellowish-gray basally and dusky at the tip
- the cere is light yellow and the eyelids flesh to pale flesh
- the eye is dark brown
BODY
- the entire body is white with the breast and abdomen immaculate, except for a few dark spots
- the flanks have dark spotting as well
- the back is usually barred or streaked with dark, sepia markings that vary in extent and intensity
WINGS
- the wings are basically white with dark tips and varying degrees of streaking or barring as for the back
- the wing tips reach one-half or two-thirds of the way down the tail in perched birds
TAIL
- the upper surface of the tail may be cleanly white or variably streaked or barred, but more narrowly in the rump area
- the undertail coverts are usually unstreaked white
LEGS
- the legs and feet are yellow and talons black
Immature White-morph - Perched
Note that immatures are overall very similar to the adults but are browner dorsally
HEAD
- finely streaked with dark brown
- the beak bluish horn with darker tip
- cere and eyelids are bluish
- the eye is very dark
BODY
- underparts white with short, dark brown streaking
- back is mostly dark brown but feathers can have broad white edgings
- whiter individuals can lack streaking on the underparts and the dark areas on the dorsal feathering can be much reduced
WINGS
- as for adults
TAIL
- as for adults
LEGS
- the legs and feet are bluish and the talons dark brown to black
SIMILAR SPECIES
Evolutionarily, the Gyrfalcon is felt to be related to the Saker Falcon of Eurasia. Under certain conditions in the field, this bird is most likely to be confused with the Peregrine Falcon. The "Peale's" race of the Peregrine Falcon is dark and may be confused with darker Gyrfalcons, especially in immature plumage. The uniformly dark underwing of the Peregrine Falcon versus the two-toned underwing of the Gyrfalcon are important distinctions. Occasionally, the Northern Goshawk may be mistaken for the large falcon as its wingbeats and wing tips are very similar. The pale, barred underwing and heavily-banded tail of the Northern Goshawk distinguishes it. Partially albinistic Red-tailed Hawks may be confused with white-morph Gyrfalcons, but dark marks on the nape and usually some red in the tail should easily separate this buteo from the falcon. In flight, wing shape and flight style will distinguish the Red-tailed Hawk immediately.
OTHER NAMES
The Gyrfalcon is also known as "Black" Gyrfalcon, "Gray" Gyrfalcon, "Gyr:, "Jerfalcon", "Partridge Hawk", and "White Gyrfalcon."
ETYMOLOGY
The genus Falco is of Latin origin and means "sickle." This is likely in reference to the shape of the talons. The species name rusticolus is also from Latin and appears to be a construct of two words - rusticus, "countryman" and incola, "inhabitant." Combined, the words therefore mean "an inhabitant of the countryside", referring to this falcon's habitat of wide open, wild spaces. Gyr is traceable to the Old High German language and the word "giri" meaning greedy. Thus, this is the greedy falcon.
MYTHOLOGY
The Gyrfalcon has long been a coveted species in the world of falconry and prized as one of the most glamorous and mystical of the birds of prey.
VOICE
The voice is generally louder, gruffer and deeper than that of the Peregrine Falcon, but many features are similar. The male's voice is higher pitched than that of the female. A gutteral "kak-kak-kak" is given by both sexes as a territorial threat and mobbing call. The male will also give this during some flight displays with his mate. The wailing call is a two syllable vocalization that is used in a variety of courtship and other heterosexual situations. It is given mainly by males but females will utter it during copulation and after receiving food. A number of variations are used. A single syllable "chup" call is given by both sexes during various courtship displays and at other times during the nesting period. A faster version of this call known as the "chattering" call is also given during ledge displays and food - passing ceremonies. A "chittering" call is given by both sexes and is featured during copulation activities. Other calls include loud trilling, screams and rattling as well as variants of some of the above calls. Food begging calls of the young are querulous mewings and juveniles have been heard giving deep raven-like calls.
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