Gyrfalcon (Falco rusticolus)
The impressive Gyrfalcon (Falco rusticolus) is the largest of all falcons. Its body measures roughly 60 cm in length and its wingspan may be as wide as 130 cm. The male is usually about one third smaller than the female and the bird may weigh between 2 to 4.5 pounds. The plumage of the Gyrfalcon varies quite considerably from white to almost black. Throughout history, this impressive bird has been highly sought after for falconry. Because of its size and rarity, it was often reserved only for those of noble birth and during the middle ages only the king had the right to possess one. The Gyrfalcon continues to be a popular bird for falconry today though modern falconers may keep their ownership of such a bird secret to avoid theft. Falconers generally refer to the male Gyrfalcon as a ‘jerkin’.
All variations of the Gyrfalcon are similar in size and have long, broad-based, pointed wings and a short, dark, hooked beak. The adult-grey morph has grey upperparts and white underparts with dark streaks. The flight feathers are pale and there is a thin moustache mark. The tail is grey with thin white bands. The adult-white morph has white plumage and a white tail with black barring on the back and wings. The adult-dark morph has dark brown upperparts and a dark tail. The underparts are heavily streaked and the flight feathers are noticeably paler than the lining on the wings.
The Gyrfalcon is circumpolar in nature and tends to nest in the arctic regions of North America, Europe, Asia, Iceland and Greenland, though they may be found elsewhere in the world when not breeding. They can live in either open, treeless plains or in swampy, forested areas and can be found near cliffs along shorelines, rivers or even in mountains. They usually nest in depressions on a protected ledge or cliff face and may even make use of an abandoned nest or a suitable man-made structure from time to time. When they nest, they generally lay 2 to 6 eggs that may take 34 to 36 days to hatch. Interestingly, they nest in arctic regions and often begin to lay their eggs in below-zero temperatures. Gyrfalcon‘s take about 2 to 3 years to become sexually mature. They generally feed on ptarmigan, grouse, seabirds, waterfowl, lemmings and ground squirrels, catching their prey either in the air or on the ground.