Great Gray Owl - Strix nebulosa

Also known as Lapland Owl, Lapp Owl

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Calls - Strix nebulosa

Typical Male		© Unknown
Juvenile begging shrieks		© Ilkka Heiskanen
Adult alarm call near young	Uinsky District, Perm, Russia, 08-08-2003	© Vladimir Kazakov

The Great Gray Owl was first described by Johann Reinhold Forster in 1772. The name "nebulosa" is derived from the Latin "Nebulosus", meaning misty or foggy. The Great Gray Owl has also been called Great Gray Ghost, Phantom of the north, Cinerous Owl, Spectral Owl, Lapland Owl, Spruce Owl, Bearded Owl and Sooty Owl.
This Owl is the provincial bird emblem of Manitoba, a province in Canada.

Description: One of the World's largest Owls, the Great Gray Owl is dark grey overall interspersed with bars and flecks of light grey and white. When perched, they appear very bulky because of their dense, fluffy plumage, long wings extending past the body, a relatively long tail, and a large head. The size of the head, and the prominent facial disk make the yellow eyes appear small. A noticeable white "moustache" strip is under the facial disk, broken by a black "bow-tie". The feet are heavily feathered and remain hidden from view.

Size: Length 61-84cm (24-33") average 72cm (28") for females, 69cm (27") for males
Wingspan up to 152cm (60") average 142cm (56") for female, 140cm (55") for males
Weight 790-1454g (28-51oz) average 1,390g (49oz) for females, 1,290g (45.5oz) for males.

Habits: Great Gray Owls fly with soft, slow wingbeats and generally do not often move more than short distances between perches and seldom glides. They fly close to the ground, usually less than 6 metres (20 feet) up, except when flying to a nest. May be very aggressive near the nest. The Great Gray Owl thermoregulates by roosting in dense cover. When hot, a Great Gray Owl will pant and droop its wings to expose an unfeathered area (apterid) under the wing.

Voice: The Great Gray Owl has a distinctive primary call which 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 800m (0.5 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. When threatened, a Great Gray Owl will snap its beak, spread its wings, and growl.

Hunting & Food: The Great Gray Owl hunts mainly during early morning and late afternoon, especially during winter, but will also hunt during other daylight hours and at night. They are often seen perched on poles or fenceposts along roads. When hunting, a Great Gray Owl will use a perch to "sit and wait" or it may hunt through the forest a metre or so (a few feet) above the ground. When ground is covered with snow, a Great Gray Owl can hunt by hearing alone and often plunges into the snow to capture small rodents moving underneath as far as 30 centimetres (12 inches).
Although a very large Owl, small rodents are their primary prey (80 to 90% of diet) with voles being the most important food in Alaska, Canada, and Oregon. Pocket gophers are the most important food in California. Other mammals taken include rats, mice, shrews, squirrels, rabbits, chipmunks, moles, and weasels. Birds are rarely captured, and include crows, small hawks, American Robin, ducks and grouse. Frogs, toads, snakes, and insects are taken very infrequently.
Pellets are very large, about 7.5 to 10 cm (3-4") long and 2.5 to 5 cm(1-2") thick. They are dark greyish-black and compact.

Breeding: Courtship involves feeding and mutual preening between mates and begins in midwinter. The male typically approaches the female, holding food in its beak, which is passed with both birds closing their eyes. 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. Northern Goshawks are very common providers of nest sites for Great Gray Owls. They also readily take to artificial platforms or nests placed in suitable habitat. Nests are usually in a forest, but with a large clearing or meadow located within 1.3km (0.8 miles). Unlike most other Owls, nests are usually tidied up and refurbished before use. Nest linings include conifer needles, deer hair, moss, and shredded bark. 2 to 5 (average 3) eggs are laid, each separated by 1 to 2 days. Incubation commences with the first egg laid and lasts 28 to 29 days. The female does all incubation and the male provides all food to the female and young. The female tears food into small pieces and feeds the young. Young leave the nest at 3 to 4 weeks and can climb well. Fledging occurs after about 8 weeks and young remain near the nest for several months, with the female caring for them.
Great Gray Owls are single-brooded but will readily lay replacement clutches if the first clutch or brood is lost. Males and females aggressively defend nests and have been known to drive off predators as large as black bears. Among other threats, ravens and Great Horned Owls prey on eggs and nestlings.
Great Gray Owls are semi-nomadic, with irregular site or mate fidelity between years. They tend to settle and nest in areas with high food resources and this may lead them to occupy the same nest for several years or move off to new areas. Nesting territories are defended from other Great Gray Owls, but foraging areas are widely overlapping. This leads to higher than expected densities, for a large bird of prey. In areas of good habitat this may be as high as 1 pair/58 hectares (5 pairs/square mile).

Mortality: They are long-lived birds, with captive owls living to 40 years of age. Mortality in the wild is often due to starvation. Natural enemies that prey on juveniles are Great Horned Owls, marten, and wolverines. Fatalities caused by humans include shootings, road kills, and electrocutions.

Habitat: Great Gray Owls inhabit a range of forested habitats. In far north America, they frequent stunted coniferous forests along the edge of the Arctic treeline, through spruce and tamarack muskeg forests further south. In the Sierra Nevada Mountains they breed in mixed conifer and red fir forests. Nesting habitat usually includes copses or islands of aspens within pure stands of conifers. Most foraging is done in open areas such as swamps, bogs, and forest clearings where there are scattered trees and shrubs that can be used as perches. During migration they may be found in estuaries, mountain meadows, and along farm fields.

Distribution: Great Gray Owls are found from Alaska across Canada, down the Northern Rocky Mountains, and northern Minnesota. They are also found in northern Europe and Asia.

Distribution of Strix nebulosa
Distribution of Strix nebulosa