[order] FALCONIFORMES | [family] Falconidae | [latin] Falco rusticolus | [authority] Linnaeus, 1758 | [UK] Gyrfalcon | [FR] Faucon gerfaut | [DE] Gerfalke | [ES] Halcon Gerifalte | [NL] Giervalk
Subspecies
| Genus | Species | subspecies | Region | Range |
| Falco | rusticolus | NA, EU | n |
Genus
Members of the genus falco are mostly medium-sized falcons, but vary from the large peregrine falcon to the small American kestrel. The wings are long and pointed and used almost continuously during flight. The bill is short, powerful, and with a distinct ‘tooth’ on each side. Most falcons of this group have a black teardrop-shaped ‘mustache’ mark on each side of the head. Falcons are fastflying birds of open country and are famous for attaining high speeds as they dive from high altitudes to knock birds out of the air.
Physical charateristics
The Gyrfalcon is the largest falcon in the world. Despite its size, it maintains a falcon-like profile with a long tail and long wings. Its wings are broader and more blunt at the tips than many other falcons. The plumage of the Gyrfalcon can take three main forms, white, gray, and dark, with many intermediate plumages. White adults have almost pure white breasts and bellies. The rest of their bodies are white mottled with brown. They have dark wingtips. Gray adults have gray upperparts with subtle darker mottling, and white underparts mottled with gray. Dark adults are dark-brownish overall above and brown streaked with white below. There is extreme sexual size dimorphism among Gyrfalcons, with males being only about 65% the size of females.
Listen to the sound of Gyrfalcon
[audio:http://www.planetofbirds.com/MASTER/FALCONIFORMES/Falconidae/sounds/Gyrfalcon.mp3]
Copyright remark: Most sounds derived from xeno-canto
| wingspan min.: | 109 | cm | wingspan max.: | 134 | cm |
| size min.: | 53 | cm | size max.: | 63 | cm |
| incubation min.: | 33 | days | incubation max.: | 35 | days |
| fledging min.: | 49 | days | fledging max.: | 35 | days |
| broods: | 1 | eggs min.: | 3 | ||
| eggs max.: | 5 |
Range
North America, Eurasia : North. Circumpolar. The Gyrfalcon is found around the Artic in Alaska, northern Canada, northern Russia, Scandinavia, Greenland and Iceland.
Habitat
The Gyrfalcon breeds in cold, arctic and subarctic latitudes, and in arctic-alpine zones at or above timberline, including sea-cliffs and islands. In Fennoscandia and Russia it breeds also in broken and barren pine or birch forests along river valleys and near mountain bases. The majority lives inland in crags and bluffs along rivers through tundra and forest-tundra, and on crags, buttes and escarpments in mountains and uplands where Lagopus spp. and other suitable birds like larids, waders and waterfowl flourish.
The most important habitat requirement is a safe nest site on a shelf of an abrupt cliff, providing shelter from mammalian predators and bad weather. Unless based on seabird colonies near-by, Gyrfalcons normally hunt over wide area of open terrain with short, sparse vegetation or willows and other shrub, or around large bodies of water. Birds dispersing elsewhere for winnter seek similar open conditions with abundant prey on moors, steppes, coastal belts, around open lakes and reservoirs, even farmland or sometimes towns.
The most important habitat requirement is a safe nest site on a shelf of an abrupt cliff, providing shelter from mammalian predators and bad weather. Unless based on seabird colonies near-by, Gyrfalcons normally hunt over wide area of open terrain with short, sparse vegetation or willows and other shrub, or around large bodies of water. Birds dispersing elsewhere for winnter seek similar open conditions with abundant prey on moors, steppes, coastal belts, around open lakes and reservoirs, even farmland or sometimes towns.
Reproduction
The Gyrfalcon breeds on a cliff ledge or in a cavity, usually in an old stick nest of another species, in particular Raven Corvus corax, but also Rough-legged Buzzard Buteo lagopus. Birds also accept artificial stick nests. A steep cliff is suitable for the species, if mammalian predators (like Red Foxes) are not able to reach the nest. The female starts laying
already in April, and the nest site has to provide also shelter from wind, rain (snow cover) and extreme exposure of sunlight by a well-developed overhang. If Gyrfalcons are short of suitable cliffs they sometimes breed in stick nests in trees, more commonly in arctic Russia and Siberia than in north-western Europe. Usually a pair has 2-5 alternate nest sites within a few kilometres, but sometimes up to ca. 15 km from each other.
The normal clutch size is 3-4 eggs, and they are incubated for 34-36 days mostly by the female. The young are brooded up to the age of 10-32 days. Fledging period is 45-50 days, and after that the young are dependent on their parents for several weeks. The young disperse from the natal territory 3-4 weeks after fledging, but some stay there for up to 5-11 weeks.
In most populations the mean productivity is 1.5-2 fledglings per breeding attempt or 2-3 fledglings per successful pair. Generally the brood size varies less than the number of successful pairs; the latter varies usually from 30 to 80% and is dependent on weather conditions during the early phase of nesting and the abundance of food. Although there may be plenty of food, heavy snowstorms or low temperature lasting for days during March and early April may prevent the female from reaching the required condition for egg laying. Some territories are occupied more or less annually, and produce a high number of young compared with territories occupied irregularly. Most birds probably start breeding at 2-3 years old. The youngest individuals of a population have a higher possibility to raise young successfully in years with abundant food supply than in years with poor food availability.
already in April, and the nest site has to provide also shelter from wind, rain (snow cover) and extreme exposure of sunlight by a well-developed overhang. If Gyrfalcons are short of suitable cliffs they sometimes breed in stick nests in trees, more commonly in arctic Russia and Siberia than in north-western Europe. Usually a pair has 2-5 alternate nest sites within a few kilometres, but sometimes up to ca. 15 km from each other.
The normal clutch size is 3-4 eggs, and they are incubated for 34-36 days mostly by the female. The young are brooded up to the age of 10-32 days. Fledging period is 45-50 days, and after that the young are dependent on their parents for several weeks. The young disperse from the natal territory 3-4 weeks after fledging, but some stay there for up to 5-11 weeks.
In most populations the mean productivity is 1.5-2 fledglings per breeding attempt or 2-3 fledglings per successful pair. Generally the brood size varies less than the number of successful pairs; the latter varies usually from 30 to 80% and is dependent on weather conditions during the early phase of nesting and the abundance of food. Although there may be plenty of food, heavy snowstorms or low temperature lasting for days during March and early April may prevent the female from reaching the required condition for egg laying. Some territories are occupied more or less annually, and produce a high number of young compared with territories occupied irregularly. Most birds probably start breeding at 2-3 years old. The youngest individuals of a population have a higher possibility to raise young successfully in years with abundant food supply than in years with poor food availability.
Feeding habits
The Willow Grouse and the Ptarmigan are the main prey of the Gyrfalcon in the whole range and throughout the year. During courtship, laying, incubation, and early nestling period falcons in some areas feed almost 100% on Lagopus spp., as well as during winter. A pair has been estimated to consume ca. 470 g of grouse per day. A pair with four young requires, on average, 1,160 g biomass/day (with a waste factor of 20%), which is equivalent to a little more than two adult grouse. During the nestling period the falcons start to take other prey in varying degrees, e.g. waders, larids, ducks and goslings, and even passerines. Gyrfalcons frequently hunt lemmings and other voles especially in Siberian arctic in high microtine years.
Breeding Gyrfalcons may hunt in an area of at least 300-600 km2, thus ranging some dozens of kilometres from their nest. They probably concentrate, however, in the most productive parts of the home range. The proportion of other prey than grouse (waterfowl, waders, larids and other mediumsized birds) is higher, on average, for pairs nesting near coast, lake, wetland or peatland areas than in homogenous heathland habitats.
Breeding Gyrfalcons may hunt in an area of at least 300-600 km2, thus ranging some dozens of kilometres from their nest. They probably concentrate, however, in the most productive parts of the home range. The proportion of other prey than grouse (waterfowl, waders, larids and other mediumsized birds) is higher, on average, for pairs nesting near coast, lake, wetland or peatland areas than in homogenous heathland habitats.
Video Gyrfalcon
httpv://www.youtube.com/watch?v=SxJCTCnDg7Q
copyright: youtube
Conservation
This species has a large range, with an estimated global Extent of Occurrence of 10,000,000 km2. It has a large global population estimated to be 10,000-100,000 individuals (Ferguson-Lees et al. 2001). Global population trends have not been quantified, but populations appear to be stable (Ferguson-Lees et al. 2001) so the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.
The Gyrfalcon is distributed circumpolarly over a large part of the tundra zone and at the northern limit of the coniferous forest zone, including arctic-alpine mountainous heath, birches and willow scrub. In Europe it breeds in Greenland, Iceland, Norway, north-western Sweden, northern Finland, northern half of the Kola Peninsula and along the timberline east of the Kanin peninsula. Within European Union the species breeds only in northern Finland and Sweden. The majority of the adult
population probably stays in the breeding area, except for high Arctic, throughout the year, but at least part of the immature and some adult birds winter in coastal areas of the Atlantic or Arctic Ocean.
The population is fairly well known in Fennoscandia and Iceland but poorly so in Greenland and especially Russia. The total European population has been estimated recently at ca. 800-1,300 without Greenland, and 1,300-2,300 if Greenland is included. According to the most recent information compiled for this report, there are 1,650-2,650 territorial pairs in the whole of Europe. Earlier estimates do not deviate markedly from this, except for Russia. Gyrfalcon populations fluctuate considerably both annually and in longer terms, depending on the abundance of Willow Grouse and Ptarmigan. The total population in Europe has probably remained at the same general level since the mid-1900s, although numbers appear to have declined at least locally in northern Fennoscandia and north-western Russia also during the 20th century.
The Gyrfalcon is distributed circumpolarly over a large part of the tundra zone and at the northern limit of the coniferous forest zone, including arctic-alpine mountainous heath, birches and willow scrub. In Europe it breeds in Greenland, Iceland, Norway, north-western Sweden, northern Finland, northern half of the Kola Peninsula and along the timberline east of the Kanin peninsula. Within European Union the species breeds only in northern Finland and Sweden. The majority of the adult
population probably stays in the breeding area, except for high Arctic, throughout the year, but at least part of the immature and some adult birds winter in coastal areas of the Atlantic or Arctic Ocean.
The population is fairly well known in Fennoscandia and Iceland but poorly so in Greenland and especially Russia. The total European population has been estimated recently at ca. 800-1,300 without Greenland, and 1,300-2,300 if Greenland is included. According to the most recent information compiled for this report, there are 1,650-2,650 territorial pairs in the whole of Europe. Earlier estimates do not deviate markedly from this, except for Russia. Gyrfalcon populations fluctuate considerably both annually and in longer terms, depending on the abundance of Willow Grouse and Ptarmigan. The total population in Europe has probably remained at the same general level since the mid-1900s, although numbers appear to have declined at least locally in northern Fennoscandia and north-western Russia also during the 20th century.
Migration
Migratory in high latitudes only. High Arctic Greenland population, mostly of white type, winters several hundred km south on coasts of southern Greenland, some crossing regularly to Iceland for winter, a few also reaching Faeroes, Britain, and Ireland more or less annually.
Continental populations mainly resident and dispersive; probably partially migratory in Russia where regular movement from tundra to taiga. Overwinter as far north as Lapland, Murmansk, and Kanin Peninsula, though others (especially juveniles) wander south and west in autumn.
Continental populations mainly resident and dispersive; probably partially migratory in Russia where regular movement from tundra to taiga. Overwinter as far north as Lapland, Murmansk, and Kanin Peninsula, though others (especially juveniles) wander south and west in autumn.
Distribution map
Literature
Title Diving speeds and angles of a gyrfalcon (Falco rusticolus)
Author(s): VA Tucker, TJ Cade, and Tucker
Abstract: An optical tracking device recorded the threedimen..[more]..
Source: The Journal of Experimental Biology 201, 2061-2070 (1998)
Title Southern Extension to the Breeding Range of the Gyrfalcon,
Falco rusticolus, in Eastern North America
Falco rusticolus, in Eastern North America
Author(s): S. Brodeur1 F. Morneau, R. Decarie, J.-L. Desgranges and J. Negro
Abstract: We report the observation of four gyrfalcon (Falco..[more]..
Source: ARCTIC VOL. 48, NO. 1 (MARCH 1995) P. 94-95
Title Gyrfalcon predation on ptarmigan: numerical and
functional responses
functional responses
Author(s): OLAFUR K. NIELSEN
Abstract: Gyrfalcon predation on ptarmigan during the breedi..[more]..
Source: Journal of Animal Ecology 1999, 68, 1034-1050