Snowy owl (Bubo scandiaca)

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Snowy owl fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Snowy owl description

Perhaps one of the most instantly recognisable of all owls, the snowy owl is characterised by its distinctive white plumage, which gives it good camouflage against the snow. Whilst the male snowy owl is almost entirely white, sometimes with some sparse dark spots or barring, the larger female is variably marked with dark bars, while the juvenile resembles the female, but is generally more heavily barred ^{(2) (4) (5) (6) (7)}. A large and powerful owl ⁽⁸⁾, the snowy owl has rudimentary ear-tufts, although these are not normally visible, and relatively small eyes, which are bright golden-yellow in colour, edged with black eyelids ^{(2) (5) (6) (7)}. The legs and toes are thickly feathered, and the short, dark beak is nearly concealed by the long facial feathers ^{(2) (5) (6)}.

The snowy owl is believed to be closely related to the eagle-owls ⁽⁷⁾, and, like eagle-owls, does not have a prominent facial disc, the flat or concave arrangement of feathers on the face, characteristic of most owls ⁽⁵⁾. The calls of this species include a deep, booming kroo-kroo or hoo-hoo, as well as a rapid, repeated cackling ka or ke, and the female may also produce a loud, intense whistling or mewing note ^{(2) (7)}.

Also known as

Arctic owl, great white owl, snow owl.

Synonyms

Bubo scandiacus, Nyctea scandiaca.

Size

Male length: 52 - 64 cm ^{(2) (3)}

Female length: 59 - 70 cm ^{(2) (3)}

Wingspan: 126 - 145 cm ⁽⁴⁾

Male weight: 0.7 - 2.5 kg ^{(2) (3)}

Female weight: 0.78 - 2.95 kg ^{(2) (3)}

Snowy owl biology

Unusually for an owl, the snowy owl hunts mainly during the day, locating prey by both sight and sound, and hunting in all weathers. Prey may be taken from the ground, in flight, or from water, and the snowy owl will sometimes hover, or even walk along the ground in search of prey. The diet is varied and includes rodents and other mammals up to the size of hares, birds up to the size of geese, and also occasionally fish, amphibians, insects, crustaceans and sometimes carrion ^{(2) (6) (7) (8) (11)}. However, the main prey, when available, is lemmings, which may be taken exclusively at times ^{(2) (6) (8)}. The snowy owl is a nomadic species whose migrations are often unpredictable, and its movements are believed to relate to variable lemming abundance ^{(6) (8)}.

The snowy owl is generally monogamous, and often pairs for life ^{(2) (6)}. During courtship, the male performs an aerial display flight, sometimes carrying a lemming in the beak or claws ^{(2) (6) (8)}, and at the start of the breeding season will defend the territory with deep hooting and with threat postures ^{(4) (8)}. Breeding usually occurs between May and September, but may be abandoned in years when lemmings are scarce ^{(2) (6) (7) (8)}. The nest is a shallow scrape on the ground, usually on a slightly elevated hummock or boulder, and is built by the female ^{(2) (4) (6) (8)}. The nest site is often aggressively defended, the adults even striking at wolves that stray too near ^{(4) (6)}. Clutch size depends on food availability, with around 3 to 5 eggs laid when food is limited, but up to 11 when conditions are good. Incubation lasts 31 to 33 days, and is performed by the female ^{(2) (6) (7) (8) (11)}, whose more mottled plumage provides good camouflage against snow and rock ⁽¹²⁾. The female also cares for the young after hatching, while the male brings food to the nest ^{(2) (6) (8) (12)}.

The young snowy owls may leave the nest after two weeks, but are unable to fly until about seven weeks old, and remain dependent on the adults for at least a further ten weeks ^{(2) (6) (7) (8)}. The snowy owl is thought to breed from about 2 years, and may live for 10 years or more in the wild, or to at least 28 years in captivity ^{(2) (6) (11)}. The irregularity of lemming abundance may mean that some individuals only breed once every three to five years ⁽⁶⁾.

Snowy owl range

The snowy owl has a circumpolar distribution around the Arctic circle, including Canada and Alaska, Scandinavia, Greenland, Iceland and Russia, and occasionally into northern Britain (Shetland Isles) ^{(2) (3) (5) (6) (9)}. Although some remain in the breeding area year-round if conditions allow, others winter further south, into the United States, northern and central Europe, Russia, China and Japan ^{(2) (3) (6)}. Occasional vagrants have even been recorded as far south as Bermuda and the Azores ^{(2) (6) (7)}.

Snowy owl habitat

The snowy owl inhabits open tundra, from near the tree-line to the edge of the polar seas, and will also use coastal fields, open moorland, and lowland salt or freshwater meadows. In winter, this species also occurs in marshes, dunes, fields, sea and lake shores, and sometimes in settled areas ^{(2) (3) (6) (8) (10)}.

Snowy owl status

Classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

Snowy owl threats

The size and remoteness of the snowy owl’s habitat make it difficult to accurately assess its population size ⁽⁴⁾. However, the species is not currently considered globally threatened ^{(2) (7) (9)}. Most of the North American breeding areas are relatively remote from the effects of human disturbance ⁽⁸⁾, although some individuals are lost due to collisions with vehicles, powerlines or aircraft, or are shot, or become entangled in fishing gear ⁽²⁾. In northern Europe, the snowy owl is believed to have declined as a result of persecution and hunting ^{(2) (4) (6) (8) (9)}, leaving a relatively small population which is consequently more vulnerable to extreme events ⁽⁹⁾. The species is harvested by native northern peoples for food, feathers and claws, but this is believed to have only a local impact ^{(2) (6)}. The potential effects of global climate change on the snowy owl and its Arctic habitats are not yet known.

Snowy owl conservation

The snowy owl is legally protected from shooting and trapping ^{(2) (6)}, and in Europe it is protected under the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention) ⁽¹³⁾ and the EC Birds Directive ⁽¹⁴⁾. Policies being put in place to protect large bird species from electrocution on powerlines and from airplane strikes should also benefit this magnificent and distinctive Arctic bird ^{(2) (6)}.

Find out more

To find out more about the conservation of this and other owl species see:

• World Owl Trust:
  http://www.owls.org/
• The Peregrine Fund:
  http://www.peregrinefund.org/
• The Birds of North America Online - Snowy Owl (Bubo scandiacus):
  http://bna.birds.cornell.edu/bna/species/010/

For more information on this and other bird species please see:

• BirdLife International:
  http://www.birdlife.org

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Glossary

Carrion

The flesh of a dead animal.

Crustaceans

Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.

Incubation

The act of incubating eggs; that is, keeping them warm so that development is possible.

Monogamous

Having only one mate during a breeding season, or throughout the breeding life of a pair.

Territory

An area occupied and defended by an animal, a pair of animals or a colony.

Tundra

Treeless, grassy plains characteristic of arctic and sub-arctic regions. They are very cold and have little rainfall.

Vagrant

Found occasionally outside normal range.

References

1. IUCN Red List (September, 2009)
   http://www.iucnredlist.org
2. del Hoyo, J., Elliott, A. and Sargatal, J. (1999) Handbook of the Birds of the World. Volume 5: Barn-Owls to Hummingbirds. Lynx Edicions, Barcelona.
3. Weick, F. (2006) Owls: Strigiformes. Annotated and Illustrated Checklist. Springer, Berlin.
4. The Cornell Lab of Ornithology - All About Birds: Snowy Owl (October, 2009)
   http://www.allaboutbirds.org/guide/Snowy_Owl/id
5. Warhol, T. (2007) Owls. Marshall Cavendish Benchmark, New York.
6. Parmelee, D.F. (1992) The Birds of North America Online: Snowy Owl (Bubo scandiacus). Cornell Lab of Ornithology, Ithaca. Available at:
   http://bna.birds.cornell.edu/bna/species/010/
7. World Owl Trust (October, 2009)
   http://www.owls.org/
8. Kaufman, K. (2001) Lives of North American Birds. Houghton Mifflin Harcourt, Boston, Massachusetts.
9. BirdLife International (October, 2009)
   http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=2236&m=0
10. Peterson, R.T., Mountfort, G. and Hollom, P.A.D. (1993) Collins Field Guide: Birds of Britain and Europe. HarperCollins Publishers, London.
11. The Peregrine Fund: Snowy Owl (Nyctea scandiaca) (October, 2009)
    http://www.peregrinefund.org/Explore_Raptors/owls/snowyowl.html
12. Burnie, D. (2001) Animal. Dorling Kindersley, London.
13. Council of Europe: Bern Convention (October, 2009)
    http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm
14. EC Birds Directive (October, 2009)
    http://www.jncc.gov.uk/page-1373