Snowy Owl

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Snowy Owl

Common Name: Snowy Owl
Genus species:
Bubo scandiacus
Recognised subspecies: None
Family: Strigidae
Order: Strigiformes




General Description:

  • Total length: 56 to 68.5 centimetres.
  • Wing: 394 to 465 mm.
  • Tail: 220 to 275 mm.
  • Weight: 1320 to 2690 grams.
  • Plumage is dominantly white.
  • Face and throat are always unmarked. Remainder of the body is barred and spotted with dusky brown throughout.
  • Large owl that lacks ear tufts, but may have indistinct or rudimentary ear tufts.
  • Eyes are small for an owl of this size, and they have a distinct golden iris.
  • Feathers around the eye are long and nearly conceal the bill.
  • Talons are partially concealed by long feathers.
  • Female has more dark markings than the male.

North American Distribution:

  • Breeding range extends from the western Aleutian Islands to northern Alaska, northern Yukon, northern Ellesmere Island and south to coastal western Alaska, northeastern Manitoba and northern Quebec.
  • Winter range extends across the southern Canadian provinces, Minnesota, and New York. May occasionally be found through central California, Nevada, Utah, Colorado, Oklahoma, and Texas.
  • The Snowy Owl does not breed within Alberta, but may be found throughout the province during the winter.

Habitat Description:

  • Information regarding home range size is not available for this species.
  • Breeding occurs in open tundra habitat, generally below 300 metres in elevation.
  • Rolling tundra is preferred, with higher areas acting as perching and nesting sites.
  • Habitat use corresponds to the presence of arctic rodents, especially lemmings.
  • During the winter, after southward migration has occurred, open areas, such as fields, marshes, coastal and shoreline areas, are used.
  • These winter habitats resemble the tundra habitat used during the breeding season.
  • May be seen in settled areas during the winter, including large metropolitan areas.

Movements and Migratory Habits:

  • Migrations of Snowy Owls are often erratic and irruptive, although some populations regularly migrate to the Great Plains Region.
  • The irregular migratory habits of the Snowy Owl are likely related to declines in prey populations.
  • Many individuals will defend territories on winter ranges.
  • Immature males, the smallest sex and age class, will migrate the furthest south, and adult females, the largest sex and age class, will remain the furthest north. There is little overlap of sex and age classes throughout the winter range.

Diet and Foraging Strategy:

  • Snowy Owls will eat lemmings and voles almost exclusively within their breeding range.
  • In areas where these rodents are not available, rabbits and the chicks of wading birds are the primary prey.
  • Within the winter range, birds and small mammals, such as mice, voles, rabbits, and hares, are the primary prey.
  • Hunting is done by pouncing on prey from a perch using a ‘sit-and-wait’ technique, or pursuing prey and catching while in flight.

Reproduction:

  • Snowy Owls are likely seasonally monogamous, with pair formation either occurring on the breeding grounds in late April to mid May, or possibly on the wintering grounds in mid winter.
  • The male likely establishes the breeding territory, and the female subsequently selects the nest site.
  • Nests are located on the ground on snow-free, raised areas that are not prone to flooding and have a view of the surrounding area.
  • The nest is constructed by the female and is a scraped out bowl, without an insulating lining of feathers or vegetation added.
  • Egg laying typically occurs in mid May and ends by early June.
  • Eggs are generally laid at 2 day intervals.
  • The white or creamy white eggs are short elliptical to sub-elliptical, and are 57 by 45 mm in size.
  • Clutch sizes are commonly 5 to 9 eggs, but may be as small as 3 eggs, or as large as 11 eggs, depending on prey availability.
  • Replacement clutches are likely produced if the first clutch is lost early in the season, but this has not been confirmed.
  • Incubation is done entirely by the female and begins when the first egg is laid.
  • Incubation period is generally 32 to 33 days.
  • Since hatching of eggs is asynchronous, there is an overlap of when incubating and brooding occur.
  • The female alone broods the young from hatching until they leave the nest.
  • Young leave the nest between 14 and 28 days of age, generally at about 25 days.
  • After leaving the nest, young will remain within their parents’ territory.
  • Fledging may occur as early as 30 days, but generally occurs at approximately 50 days of age.

Conservation Status:

  • Federal: Not at Risk
  • Provincial: Secure


References Snowy Owl photo © 2007 Thomas Maier. Retrieved from www.istockphoto.com/stock-photo-2741286-snowy-owl-portrait.php on 22/09/09. Used with permission.

Alberta Sustainable Resource Development (ASRD). 2008. Search species and status category. <http://www.srd.gov.ab.ca/fishwildlife/speciesatrisk/statusofalbertawildspecies/search.aspx>. Accessed 5 March 2009.

Godfrey, W.E. 1986. Birds of Canada, revised edition. National Museum of Natural Sciences, Ottawa, Canada.

Government of Canada. Species at risk public registry. 2008. <http://www.sararegistry.gc.ca/sar/index/default_e.cfm>. Accessed 5 March 2009.

Parmalee, D.F. 1992. Snowy owl (Bubo scandiacus), The Birds of North America Online (A. Poole, Ed.). <http://bna.birds.cornell.edu/bna/species/010doi:10.2173/bna.10>. Accessed 6 March 2009.

Johnsgard, P.A. 2002. North American Owls. Second edition. Smithsonian Institution Press, Washington, USA.

Lynch, W. 2007. Owls of the United States and Canada. The Johns Hopkins University Press, Baltimore, Maryland, USA.

Salt, W.R. and J.R. Salt. 1976. The birds of Alberta. Hurtig Publishers, Edmonton, Alberta, Canada.