Snowy Owl - Bubo scandiacus
Formerly Nyctea scandiaca
Calls - Bubo scandiacus
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.
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
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
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
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
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 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.
Campbell, Wayne. 1994. "Know Your Owls". Axia Wildlife
Page compiled by Deane Lewis. Page last updated 2013-07-02
OwlPages.com Owl Species ID: 110.010.000