[order] STRIGIFORMES | [family] Strigidae | [latin] Strix nebulosa | [authority] Forster, 1772 | [UK] Great Grey Owl | [FR] Chouette lapone | [DE] Bartkauz | [ES] Carabo Lapon | [NL] Laplanduil
Subspecies
Monotypic species
Genus
Members of the genus Strix are the wood owls. They are medium to large owls, having a large, rounded head and no ear-tufts. The comparatively large eyes range from yellow through to dark brown. Colouring is generally designed fro camouflage in woodland, and a number of the member of this genus have colour phases. There are 20 species scattered practically throughout the globe with the exception of Australasia, the South Pacific and Madagascar, where the genus Ninox takes its place. There being no clear generic differences between Strix and Ciccaba genera, and DNA evidence suggesting very close relationships, many authorities now merge the latter into the former.
Physical charateristics
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.
Listen to the sound of Great Grey Owl
[audio:http://www.planetofbirds.com/MASTER/STRIGIFORMES/Strigidae/sounds/Great Grey Owl.mp3]
Copyright remark: Most sounds derived from xeno-canto
| wingspan min.: | 120 | cm | wingspan max.: | 150 | cm |
| size min.: | 61 | cm | size max.: | 84 | cm |
| incubation min.: | 28 | days | incubation max.: | 29 | days |
| fledging min.: | 56 | days | fledging max.: | 29 | days |
| broods: | 1 | eggs min.: | 2 | ||
| eggs max.: | 5 |
Range
North America, Eurasia : North
Habitat
In North America, Strix nebulosa inhabits dense coniferous forests in Canada, and montane coniferous forests of the western States. It usually prefers pine and fir forests, rarely straying far out onto tundra barrens and muskeg marshes. Nests in mature poplar woodlands, well secluded from human activities, and in spruce stands with islands of tamarack. In winter, it may inhabit forests, sparse woodland edges bordering open fields, weedy fields with posts or scattered low trees or bushes, or brackish tidal meadows.
Reproduction
Breeding takes place in late winter with the pair generally utilizing an abandoned hawk or crow’s nest. The female Strix nebulosa lays eggs in March- June, depending on temperature range (egg laying may be delayed in deep snow years). Two to five dull white oval eggs are laid and are incubated by the female Strix nebulosa for a period of 28-29 days. The owlets hatch covered by soft white down with their eyes open. Both parents feed the young by bringing food to the nest, tearing into very small pieces that are eagerly consumed by the little ones. Soon the down begins to disappear and is replaced by feathers. Once the owlets are ‘feathered out’ they begin the pre-flight exercises. They can be observed walking around the top of their nest flapping their wings and gripping the nest edge with their talons. Young leave nest after three to four weeks with the ability to climb well.
Feeding habits
It feeds primarily on small rodents such as voles and pocket gophers. Small rodents composed 80-90% percent of the diet while other mammals (mainly shrews) and birds composed the remainder.
The Great Gray Owl hunts by perching on a tree overlooking a meadow or open area. The owl’s 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 plunges into the snow to grab the rodent with its sharp talons. Fresh “plunge marks” will occasionally show an imprint of the owl’s outstretched wing feathers where the owl dropped into the snow. In many areas these marks are often the only indication that Great Gray Owls are in the area.
The Great Gray Owl hunts by perching on a tree overlooking a meadow or open area. The owl’s 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 plunges into the snow to grab the rodent with its sharp talons. Fresh “plunge marks” will occasionally show an imprint of the owl’s outstretched wing feathers where the owl dropped into the snow. In many areas these marks are often the only indication that Great Gray Owls are in the area.
Video Great Grey Owl
httpv://www.youtube.com/watch?v=ItX9s93Gzlo
copyright: youtube
Conservation
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be fluctuating, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Strix nebulosa resides in Alaska, Canada, the higher elevations of the Rocky Mountain States, northern Minnesota and northern Wisconsin. Also, S. nebulosa breeds from northern Yukon to northern Manitoba and northern Ontario, south locally to central California, northern Idaho, northwestern Wyoming, central Saskatchewan, northern Minnesota, and south central Ontario. Winters generally through the breeding range, wandering south irregularly to the northern tier of States. It also occurs widely across Europe and Asia.
Strix nebulosa resides in Alaska, Canada, the higher elevations of the Rocky Mountain States, northern Minnesota and northern Wisconsin. Also, S. nebulosa breeds from northern Yukon to northern Manitoba and northern Ontario, south locally to central California, northern Idaho, northwestern Wyoming, central Saskatchewan, northern Minnesota, and south central Ontario. Winters generally through the breeding range, wandering south irregularly to the northern tier of States. It also occurs widely across Europe and Asia.
Migration
Resident and nomadic; movements patterns variable, stable in some areas and/or years, highly irruptive in others, influenced by prey availability. Both altitudinal and latitudinal movements occur. Birds probably move also to avoid deep snow, although known to winter well N (as well as S) of its taiga breeding range in Russia. Irrupts into areas with abundant food supply (Voles), occasionally breeding in such places well outside normal range. In North America, wanders S to NE Wisconsin and N Michigan; in Europe, has reached N Germany and Ukraine. When migrating, can occur in loose concentrations, probably in response to abundant prey.
Distribution map
Literature
Title Landscape Featur es and Characteristics of Great Gray Owl ( Strix nebulosa) Nests in
Fragmented Landscapes of Central Alberta
Fragmented Landscapes of Central Alberta
Author(s): D.P. Stepnisky
Abstract: Forest fragmentation through timber harvesting, ag..[more]..
Source: 2nd Owl Symposium
Title Sex and Age Composition of Great Gray Owls
Author(s): Robert W. Nero and Herbert W.R. Copland
Abstract: In the winter 1995/1996, a nearly continent-wide m..[more]..
Source: 2nd Owl Symposium
Title Nest Site Habitat and Prey Use of a
Breeding Pair of Great Gray Owls in the
Upper Peninsula of Michigan
Breeding Pair of Great Gray Owls in the
Upper Peninsula of Michigan
Author(s): R. Gregory Corace et al.
Abstract: We describe nest site habitat characteristics at t..[more]..
Source: The Passenger Pigeon, Vol. 68, No. 4, 2006
Title The Great Gray Owl as a Predator on Pocket Gophers
Author(s): C. A. TRYON, JR.
Abstract: I observed a Great Gray Owl (Scotiaptex nebulosa n..[more]..
Source: Wilson bull. Vol. 55, No. 2
Title NESTING CHRONOLOGY OF THE GREAT GRAY OWL AT AN ARTIFICIAL NEST SITE IN THE SIERRA NEVADA
Author(s): THOMAS W. BECK AND RANDALL A. SMITH
Abstract: The California Great Gray Owl (Strix nebulosa) pop..[more]..
Source: J. Raptor Res. 21(3):116-118