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  ScienceZoologyBirdsOrder Strigiformes


great gray owlGreat Gray Owl

Strix nebulosa

Description

One of the larger owls, the great gray is 24-33 inches long, has a wingspan of 54-60 inches, and weighs 27-52 ounces.

Ventrally, this owl is exhibits varying shades of dark and light grays, browns, and white. The dorsal side has a little less white than the ventral side. There is an obvious facial disk, with many dark concentric rings. Distinctive marks include a black chin spot above two white "mustaches" and prominent white collar on the front of the neck.

Distribution and Habitat

The great gray owl has a circumpolar range that in North America includes most of Alaska and Canada, the higher elevations of the Rocky Mountain States, northern Minnesota, and northern Wisconsin It also occurs widely across northern Europe and Asia. It generally prefers pine and fir forests, but can also be found in sparse woodland edges bordering open fields, weedy fields with posts or scattered low trees or bushes, and brackish tidal meadows.

Diet

This owl hunts by perching on a tree (or other suitable vantage point) overlooking a meadow or open area. Keen hearing enables it to accurately determine the location of its prey, even under two feet of snow or in tunnels. Once the owl locates some food, it silently glides from its perch and grabs the prey with its sharp talons. This owl can plunge through up to two feet of snow to get its prey. Small rodents comprise 80-90% percent of the diet, with other mammals (mainly shrews) and birds making up the rest.

Reproduction

Courtship involves feeding and mutual preening between mates and begins in midwinter. The male selects possible nest sites and attracts its mate with calls. Several sites are inspected before she chooses the nest site. The great gray owl nests primarily in stick nests made by hawks, ravens, or crows, in the hollowed out top of large-diameter snags, or on the top of clumps of mistletoe, and in Europe sometimes on the forest floor.

Two to five dull white oval eggs are laid sometime between March and June. They are incubated by the female alone for 28-29 days, during which time the male brings her food. The owlets hatch covered by soft white down with their eyes open. The male does all of the hunting while the owlets are in the nest, but the feeding is usually done by the female, who tears the prey into pieces small enough for the owlets to swallow. Young leave nest after three to four weeks with the ability to climb well.

Other Information

Great gray owls are most active at night, but also at dusk and just before dawn. They are sometimes active during the day in breeding season.

This owl does not migrate, but it will move in response to rodent populations.

Great gray owls fly with soft, slow wingbeats and generally do not often move more than short distances between perches and seldom glide. They fly close to the ground, usually less than 20 feet up, except when flying to a nest.

The distinctive primary call is a very soft, low-pitched hoot "whooo-ooo-ooo-ooo" with the notes emitted slowly over a 6 to 8 second period. Calls are repeated every 15 to 30 seconds. This call is used as a territorial declaration and can be heard up to a half mile away under good conditions. Territorial calling begins after dusk, peaks before midnight, then peaks again later. Males and females also give a single hoot when near the nest. Females give an excited "ooo-uh" when the male arrives with food. When excited near the nest adults growl, shriek, hoot, wail, and snap their bills.

The great gray owl is the official bird emblem of Manitoba, Canada.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Aves
order Strigiformes
family Strigidae
genus & species Strix nebulosa


Animal Diversity Web http://animaldiversity.org/accounts/Strix_nebulosa/
The Owl Pages http://www.owlpages.com/owls/species.php?s=1770

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  The Robinson Library > Science > Zoology > Birds > Order Strigiformes

This page was last updated on March 18, 2016.

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