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Snowy Owl - Bubo scandiacus

Formerly Nyctea scandiaca

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Calls - Bubo scandiacus
Alarm/Disturbed Calls Male. Padjelanta, Sweden. July 1982. CC Niels Krabbe

Introduction: The Snowy Owl is a large diurnal white Owl with a rounded head, yellow eyes and black bill. The name "scandiacus" is a Latinised word referring to Scandinavia, as the Owl was first observed in the northern parts of Europe. Some other names for the Snowy Owl are Snow Owl, Arctic Owl, Great White Owl, Ghost Owl, Ermine Owl, Tundra Ghost, Ookpik, Scandinavian Nightbird, White Terror of the North, and Highland Tundra Owl. It is the official bird of Quebec, Canada.

[For help with terms used in the description, see parts of an owl. For general characteristics common to most owl species, see owl physiology.]

Description: Sexes differ in the degree of dusky patterning on the white plumage.
Male: The facial disc is white and ill-defined. Eyes are bright yellow, rimmed by blackish eyelid edges. The cere is dark grey, and is normally concealed by dense feathering. The bill is blackish. Ear-tufts are so small, they are not visible.
The upperparts are plain white, with a few dusky spots on the tiny ear-tufts, the alula and at the tips of some primaries and secondaries.
The tail feathers are nearly all white, sometimes with indistinct terminal bars. Underparts are all white.
Tarsi and toes are thickly feathered white. Claws are blackish.
Female: Spotted and slightly barred brown on the crown and upperparts. Flight and tail feathers are faintly barred brown. Underparts are white, with brown spotting and barring on the flanks and upper breast.
Juveniles are dark greyish-brown.

Size: Length 51-68.5cm. Wingspan 137-164cm. Tail length 206-241mm. Weight 1134-2000g. Females are larger and heavier than males.

Habits: Snowy Owls are active during the daytime, from dawn to dusk. They have a direct, strong, and steady flight with deliberate, powerful downstrokes and quick upstrokes. They make short flights, close to the ground, from perch to perch, and usually perches on the ground or a low post. During hot weather, they can thermoregulate by panting and spreading their wings. Snowy Owls are very aggressive when defending their nest.

Voice: The Snowy Owl is virtually silent during nonbreeding seasons. The typical call of the male is a loud, harsh, grating bark, while the female has a similar higher pitched call. During the breeding season males have a loud, booming "hoo, hoo" given as a territorial advertisement or mating call. Females rarely hoot. Its alarm call is a guttural "krufff-guh-guh-guk". When excited it may emit a loud "hooo-uh, hooo-uh, hooo-uh, wuh-wuh-wuh". Other sounds are dog-like barks, rattling cackles, shrieks, hissing, and bill-snapping.
Nestlings "cheep" up to 2 weeks of age, then hiss and squeal.

Hunting & Food: Most hunting is done in the "sit and wait" style. These Owls are highly diurnal, although they may hunt at night as well. Prey are captured on the ground, in the air, or snatched off the surface of water bodies. When taking snowshoe hares, a Snowy Owl will sink its talons into the back and backflap until the hare is exhausted. The Owl will then break its neck with its beak. Snowy Owls have been known to raid traplines for trapped animals and bait, and will learn to follow traplines regularly. They also snatch fish with their talons. Small prey up to small hares are swallowed whole, while larger prey are carried away and torn into large chunks. Small young are fed boneless and furless pieces. Large prey are carried of in the Owl's talons, with prey like lemmings being carried in the beak.
Snowy Owls are mainly dependent on lemmings and voles throughout most of their Arctic and wintering range. When these prey are scarce they are an opportunistic feeder and will take a wide range of small mammals and birds. Some mammal prey include mice, hares, muskrats, marmots, squirrels, rabbits, prairie dogs, rats, moles, and entrapped furbearers. Birds include ptarmigan, ducks, geese, shorebirds, Ring-necked Pheasants, grouse, American coots, grebes, gulls, songbirds, and Short-eared Owls. Snowy Owls will also take fish and carrion.
Some nesting Owls switch from lemmings and voles to young ptarmigan when they become available. Snowy Owls do not hunt near their nests, so other birds, such as Snow Geese, often nest nearby to take advantage of the Owls driving off predators such as foxes.
Snowy Owls produce large, rough-looking cylindrical pellets with numerous bones, feathers, and fur showing. They are usually expelled at traditional roosting sites and large numbers of pellets can be found in one spot. When large prey are eaten in small pieces with little roughage, pellets will not be produced.

Breeding: Courtship behaviour can begin in midwinter through to March and April, well away from breeding areas. Males will fly in undulating, moth-like flight when females are visible. On the ground males will bow, fluff feathers, and strut around with wings spread and dragging on the ground. Males kill and display prey in caches to impress females, often feeding the female. The Snowy Owl nests almost exclusively on the ground, where the female makes a shallow scrape with her talons on top of an elevated rise, mound, or boulder. Abandoned eagle nests and gravel bars are used occasionally. Nests may be lined with scraps of vegetation and Owl feathers. Nest sites must be near good hunting areas, be snow-free, and command a view of surroundings. There is little breeding site-faithfulness between years or mates in some areas, but in other areas, a pair of Owls may nest in the same spot for several years. Territories around nests range from 1.5 to 6.5 square kilometres (0.6 to 2.5 square miles), and overlap with other pairs.
Breeding occurs in May, Clutch and brood sizes are heavily dependent on food supply. Snowy Owls may not nest at all during years of low lemming numbers. Clutch sizes normally range from 5 to 8 white eggs but may be as many as 14 eggs during high lemming years. They are laid at approximately 2 day intervals and average about 57 x 45 mm.  The female incubates while the male brings her food and guards the nest. Eggs hatch in 32-34 days at two day intervals, leading to large age differences in nests with large clutch sizes. Young are covered in white down. Young begin to leave the nest after about 25 days, well before they can fly. They are fledged at 50 to 60 days. Both parents feed and tend the young, and are fiercely protective and may attack intruders up to 1 kilometre (0.6 miles) from the nest! Nestling Owls require about 2 lemmings/day and a family of Snowy Owls may eat as many as 1,500 lemmings before the young disperse. Snowy Owls are single brooded and likely do not lay replacement clutches if their first clutch is lost. Almost 100% nesting success can be achieved during good vole years.
Numbers fluctuate wildly, usually in concert with lemming and vole numbers. For Example, Banks Island may have 15,000 to 20,000 Snowy Owls during good lemming years and only 2,000 during low lemming years with densities ranging from 1 Owl per 2.6 square kilometre (1 Owl per square mile) in good lemming years to 1 Owl per 26 square kilometres (1 Owl per 10 square miles) in low lemming years.

Mortality: Snowy Owls can live at least 9.5 years in the wild and 35 years in captivity. Natural enemies are few - Arctic foxes and wolves prey upon them on their tundra breeding grounds, while skuas and jaegers may take eggs or chicks.

Habitat: The Snowy Owl is a bird of Arctic tundra or open grasslands and fields. They rarely venture into forested areas. During southward movements they appear along lakeshores, marine coastlines, marshes, and even roost on buildings in cities and towns. In the Arctic, they normally roost on pingaluks (rises in the tundra) and breed from low valley floors up to mountain slopes and plateaus over 1000m elevation. When wintering in the Arctic, they frequent wind-swept tundra with little snow or ice accumulation. At more southern latitudes they typically frequents agricultural areas.

Distribution: Circumpolar - Arctic regions of the old and new worlds.
In North America, Snowy Owls breed in the western Aleutian Islands, and from northern Alaska, northern Yukon, and Prince Patrick and northern Ellesmere islands south to coastal western Alaska, northern Mackenzie, southern Keewatin, extreme northeastern Manitoba, Southampton and Belcher islands, northern Quebec and northern Labrador. The Snowy Owl is highly nomadic. During periods of lemming and vole population crashes in the Arctic, or excessive cold and snow in winter, mass movements of Snowy Owls occur into southern Canada and northern United States. These invasions occur every 3 to 5 years, but are highly irregular. Adult females stay furthest north while immature males move furthest south during these incursions.

Distribution of Snowy Owl - Bubo scandiacus
Distribution of the Snowy Owl Bubo scandiacus

Status: Locally abundant during good lemming years, rare at some locations during other times.

Original Description: Linnaeus, Carolis. 1758. Systema Naturae ed. 10, p. 92.

References:

Boyer and Hume. 1991. "Owls of the World". BookSales Inc
Campbell, Wayne. 1994. "Know Your Owls". Axia Wildlife
König, Claus & Weick, Friedhelm. 2008. "Owls: A Guide to the Owls of the World (Second Edition)". Yale University Press
König, Weick and Becking. 1999. "Owls: A Guide to the Owls of the World". Yale University Press
Long, Kim. 1998. "Owls: A Wildlife Handbook". Johnson Books
Mikkola, Heimo. 1983. "Owls of Europe". Buteo Books
Voous, Karel H. 1988. "Owls of the Northern Hemisphere". The MIT Press

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Page compiled by . Page last updated 2013-07-02

OwlPages.com Owl Species ID: 110.010.000