Great grey owl

Lore & Background

The great grey owl is one of several Strix species found in both Eastern and Western Hemispheres, alongside the tawny owl and Ural owl. Its two recognized subspecies are S. n. nebulosa, ranging across North America from central Alaska to Quebec and south to northern California and Minnesota, and S. n. lapponica, found across northern Eurasia from Fennoscandia through Siberia to northeastern China. The first great grey owl recognized by science was found in Canada in the late 18th century.

Adults have large, rounded heads with grey faces and yellow eyes with darker circles around them. The underparts are light with dark streaks; the upper parts are grey with pale bars. This owl does not have ear tufts and has the largest facial disc of any raptor. A white collar or 'bow-tie' is just below the beak. The long tail tapers to a rounded end. In length, the great grey owl is believed to exceed the Eurasian eagle-owl and Blakiston's fish owl as the world's largest owl, though it is outweighed by those species and several others. Much of its size is deceptive, as fluffy feathers and a large head obscure a lighter body.

The call of the adult is a series of very deep, rhythmic 'who's, usually given in correlation to territories or interactions with offspring. At other times, adults are normally silent. Young may chatter, shriek, or hiss. Tame owls may produce higher-pitched hoots when given food by humans.

Reader's Guide

The great grey owl is significant as the world's largest owl by length and as the only Strix species spanning both Eastern and Western Hemispheres. Its large facial discs and asymmetrical ears give it exceptional hearing, allowing it to locate prey moving beneath up to 60 cm of snow and to 'snow-plunge' to capture them. This adaptation is unique among owls, with only infrequent similar behavior in other large Strix species.

The species breeds in dense coniferous forests of the taiga near open areas, and in mixed oak woodlands in Oregon and California. It does not build nests but uses those of other large birds, broken-topped trees, cavities, and man-made platforms. Clutches contain 2–5 eggs, with incubation about 30 days. Reproduction is tied to small mammal populations; in years of scarcity, the owl may not nest. Though not migratory, it is somewhat nomadic, moving when food is scarce.

In California, the species is listed as endangered under the California Endangered Species Act, with fewer than 300 birds estimated in 2015. A genetically isolated population in Yosemite has been proposed as a separate subspecies (S. n. yosemitensis). The great grey owl's reliance on specific habitats and prey makes it a key indicator of boreal and montane ecosystem health.

Did You Know?

• The great grey owl is the world's largest species of owl by length, though it is outweighed by the Eurasian eagle-owl and Blakiston's fish owl.
• It has the largest facial disc of any raptor, which helps focus sound for hunting.
• The great grey owl can locate and capture prey moving beneath 60 cm of snow using only its hearing.
• A 2015 study estimated fewer than 300 great grey owls in California, where the species is listed as endangered.