Well Come To Nature

Friday, 9 September 2011

Snow Owl


This yellow-eyed, black billed white bird is easily recognizable. It is 52–71 centimetres (20–28 in) long with a 125–150 centimetres (49–59 in) wingspan. Also, these birds can weigh anywhere from 1.6–3 kilograms (3.5–6.6 lb).It is one of the largest species of owl and in North America is on average the heaviest owl species. The adult male is virtually pure white, but females and young birds have some dark scalloping; the young are heavily barred, and dark spotting may even predominate. Its thick plumage, heavily-feathered taloned feet, and coloration render the Snowy Owl well-adapted for life north of the Arctic Circle.
Snowy Owl calls are varied, but the alarm call is a barking, almost quacking krek-krek; the female also has a softer mewling pyee-pyee or prek-prek. The song is a deep repeated gawh. They may also clap their beak in response to threats or annoyances. While called clapping, it is believed this sound may actually be a clicking of the tongue, not the beak.
Ecology:-
The Snowy Owl is typically found in the northern circumpolar region, where it makes its summer home north of latitude 60 degrees north. However, it is a particularly nomadic bird, and because population fluctuations in its prey species can force it to relocate, it has been known to breed at more southerly latitudes. During the last glacial, there was a Central European paleosubspecies of this bird, Bubo scandiacus gallicus, but no modern subspecies are recognized.
This species of owl nests on the ground, building a scrape on top of a mound or boulder. A site with good visibility, ready access to hunting areas, and a lack of snow is chosen. Gravel bars and abandoned eagle nests may be used. Breeding occurs in May, and depending on the amount of prey available, clutch sizes range from 5 to 14 eggs, which are laid singly, approximately every other day over the course of several days. Hatching takes place approximately five weeks after laying, and the pure white young are cared for by both parents. Both the male and the female defend the nest and their young from predators. Some individuals stay on the breeding grounds while others migrate.
Range:-
Snowy Owls nest in the Arctic tundra of the northermost stretches of Alaska, Canada and Eurasia. They winter south through Canada and northern Eurasia, with irruptions occurring further south in some years. Snowy Owls are attracted to open areas like coastal dunes and prairies that appear somewhat similar to tundra. They have been reported as far south as Texas, Georgia, the American Gulf states, southernRussia, northern China and even the Caribbean. Between 1967 and 1975, Snowy Owls bred on the remote island of Fetlar in the Shetland Isles north of Scotland, UK. Females summered as recently as 1993, but their status in the British Isles is now that of a rare winter visitor toShetland, the Outer Hebrides and the Cairngorms.In January 2009, a Snowy Owl appeared in Spring Hill, Tennessee, the first reported sighting in the state since 1987.


Hunting and Diet:-
This powerful bird relies primarily on lemmings and other small rodents for food during the breeding season, but at times of low prey density, or during the ptarmigan nesting period, they may switch to juvenile ptarmigan. They are opportunistic hunters and prey species may vary considerably, especially in winter. They feed on a wide variety of small mammals such as meadow voles anddeer mice, but will take advantage of larger prey, frequently following traplines to find food. Some of the larger mammal prey includes hares, muskrats, marmots, squirrels, rabbits, raccoons, prairie dogs, rats, moles, and entrapped furbearers. Birds preyed upon include ptarmigan, ducks, geese,shorebirds, ring-necked pheasants, grouse, American coots, grebes, gulls, songbirds, and even other raptors, including other owl species. Snowy Owls are also known to eat fish and carrion. Most of the owls' hunting is done in the "sit and wait" style; prey may be captured on the ground, in the air or fish may be snatched off the surface of bodies of water using their sharp talons. Each bird must capture roughly 7 to 12 mice per day to meet its food requirement and can eat more than 1,600 lemmings per year.

Snowy Owls, like many other birds, swallow their small prey whole. Strong stomach juices digest the flesh, while the indigestible bones, teeth, fur, and feathers are compacted into oval pellets that the bird regurgitates 18 to 24 hours after feeding. Regurgitation often takes place at regular perches, where dozens of pellets may be found. Biologists frequently examine these pellets to determine the quantity and types of prey the birds have eaten. When large prey are eaten in small pieces, pellets will not be produced.

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