Great grey owl
Great grey owl | |
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Strix nebulosa | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Strigiformes |
Family: | Strigidae |
Genus: | Strix |
Species: | S. nebulosa
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Binomial name | |
Strix nebulosa Forster, 1772
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The great grey owl (Strix nebulosa) (also great gray owl in
Description
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. There is a white collar or "bow-tie" just below the beak. The long tail tapers to a rounded end.
In terms of length, the great grey owl is believed to exceed the Eurasian eagle-owl and the Blakiston's fish owl as the world's largest owl. [citation needed] The great grey is outweighed by those two species as well as several others, including most of the genus Bubo.[4] Much of its size is deceptive, since this species' fluffy feathers, large head and the longest tail of any extant owl obscure a body lighter than that of most other large owls. The length ranges from 61 to 84 cm (24 to 33 in), averaging 72 cm (28 in) for females and 67 cm (26 in) for males. The wingspan can exceed 152 cm (5 ft 0 in), but averages 142 cm (4 ft 8 in) for females and 140 cm (4 ft 7 in) for males. The adult weight ranges from 580 to 1,900 g (1.28 to 4.19 lb), averaging 1,290 g (2.84 lb) for females and 1,000 g (2.2 lb) for males.[5] The males are usually smaller than females, as with most owl species.[3]
The call of the adult is a series of very deep, rhythmic 'who's, which is usually given in correlation to their territories or in interactions with their offspring. At other times, adults are normally silent. The young may chatter, shriek, or hiss. Tame owls may produce higher-pitched hoots when given food by humans.
Taxonomy
There are two recognized subspecies of the great grey owl spread across North America and Eurasia.[6]
- S. n. nebulosa (Forster, 1772): North America from central Alaska eastward across Canada to south-western Quebec, and south to northern California, northern Idaho, western Montana, Wyoming, and north-eastern Minnesota.
- S. n. lapponica (Thunberg, 1798): Northern Eurasia, from Fennoscandia through Siberia to Sakhalin and Kamchatka Krai to Lithuania, Lake Baikal, Kazakhstan, Mongolia, Manchuria and north-eastern China.
Habitat
In northern areas their breeding habitat is often the dense coniferous forests of the taiga, near open areas, such as meadows or bogs. In Oregon and California this owl has been found nesting in mixed oak woodlands. Once believed to require a cold climate, it is now known that this bird survives in a few areas where summer temperatures exceed 100 °F (38 °C).[citation needed]
Range
They breed in
. They are permanent residents, although northerly populations may move south and southeast when food is scarce. In Europe they are found breeding in Norway and Sweden and more numerously through Finland and Russia. Even though the species occurs in Europe, the first great grey owl recognized by science was found in Canada in the late 18th century.There are sedentary populations in the Pacific states of California, Oregon, and Washington. The great grey owl in this region is found in disjunct areas of appropriate habitat. In winter these birds do not move far but may go downslope to escape deep snow as they must capture their prey on the ground.
In Oregon, the great grey owl breeding range is scattered from the Siskiyou Mountains in the southwest to the Blue Mountains in the northeast. Two bird festivals each May feature field trips to try to see the species: The Ladd Marsh Festival in La Grande, OR and the Mountain Bird Festival in Ashland, OR.
A 2015 study in California estimated there were fewer than 300 birds in the state at the time. The species is listed as Endangered under the California Endangered Species Act.[7][full citation needed] The California range for the species includes a small extension of the Oregon population, north of Alturas. In addition breeding has been confirmed in the Tahoe National Forest east of Nevada City; in the Sierra Nevada foothills south of I-80 at around 2,000 feet (610 m) elevation; and for the population clustered around Yosemite. In Yosemite is where the first nest south of Canada was found in 1914. A study of the Yosemite owls shows that this population has been genetically isolated from populations in Oregon and farther north for more than 25,000 years. Biologists working on that study suggest that the Yosemite population should be considered a separate sub-species (Strix nebulosa yosemitensis).[8] Nearby populations at lower elevations were not tested.
In Washington state, great grey owls are found in the southeast where mountains extend up from Oregon and in the Colville National Forest. Only a handful of great grey owl nests have ever been found in Washington state.
Farther east in the western United States, great grey owls breed in Idaho, Montana, and Wyoming, as far south as the Grand Teton and Yellowstone National Parks.
In northeastern North America, the owls are found year-round in southern Quebec and Ontario, but individuals will sometimes move further south in winter into
Breeding
Great grey owls do not build nests, so they typically use nests previously used by a large bird, such as a
The abundance of food in the area usually affects the number of eggs a female lays, a feature quite common in northern owl species. In years when small mammal populations are very low the great grey owl may not attempt nesting; thus their reproduction is connected to the sometimes extreme fluctuations of small mammal populations. Also, great grey owls may not nest in years of drought. If food is scarce, they may travel a fair distance to find more prey, with considerable movements by large numbers in some years of particularly scarce prey. Though they do not migrate, many are at least somewhat nomadic.
One alert landowner in northeast Oregon, Andy Huber, helped a female great grey owl raise her four nestlings after a great horned owl killed the male. Huber live-trapped small mammals and then released them at the nest site, and the female took these to the nestlings. As the owlets matured and began flying they came for the prey on their own. Huber and the mother owl raised all four owlets successfully.[11]
Feeding
These birds wait, listen, and watch for prey, then swoop down; they also may fly low through open areas in search of prey. They frequently hunt from a low listening post which can be a stump, low tree limb, fence post, or road sign. Their large facial discs, also known as "ruffs", focus sound, and the asymmetrical placement of their ears assists them in locating prey, because of the lack of light during the late and early hours in which they hunt. On the nesting grounds, they mainly hunt at night and near dawn and dusk; at other times, they are active mostly during the night.
They have excellent hearing, and may locate (and then capture) prey moving beneath 60 cm (2.0 ft) of snow in a series of tunnels solely with that sense. They then can crash to a snow depth roughly equal to their own body size to grab their prey. Only this species and, more infrequently, other fairly large owls from the genus
Unlike the more versatile eagle and horned owls, great grey owls rely almost fully upon small
Threats
The harvest of
Other dangers to great grey owls include rodenticides, collisions with vehicles, and the
Due to their large size, great grey owls have few natural predators. Great horned owls, various small carnivores, and black bears have been documented preying on young, but such predators rarely threaten adults, and owls have been known to fend off animals as large as black bears when defending their nests.[15] The only known predator of adult great grey owls is the Eurasian eagle-owl (Bubo bubo), which occasionally preys on the former in parts of Europe.[16]
Territorial behavior
The great grey owl is not as aggressive as most other alpha predators. They are less likely to attack each other or potential threats than are other large predatory birds. They do not protect a large nesting territory, nor do they defend hunting territories through aggression. As an exception, the female is aggressive in protecting eggs and owlets. She is especially alert and aggressive when fledglings first leave the nest but cannot yet fly, and thus are extremely vulnerable.
This lack of territorial aggressiveness makes the great grey owl difficult to find in the field. Most owls respond to their own species calls if played back in a nesting territory. Great grey owls will often ignore such calls. They also do not flush every time a human approaches or drives past. The great grey owl often remains still even if a human is nearby and therefore they are often overlooked or unnoticed.
Provincial bird
The great grey owl is the provincial bird of Manitoba.
Captivity
As of 2016, there are four great grey owls captive in Oregon and California. Two live at Blue Mountain Wildlife near Pendleton, Oregon, a third lives at Lindsay Museum in Walnut Creek, California,[17] and the fourth lives at CuriOdyssey in San Mateo, California.[18]
A captive wild injured great grey owl, Boris, resides at the Alaska Raptor Center in Sitka, Alaska. Boris was found north of Anchorage with a trauma to his right wrist, leaving him flightless.[19]
Another captive wild injured great grey owl, Errol, lives at the Alaska Zoo in Anchorage, Alaska. Errol came to the zoo from Wild Bird Rescue after injuring himself while colliding with the tire of a parked car. [20]
The Eurasian subspecies of the grey owl is very commonly kept in European zoos.
In art
A great grey owl with human hands is depicted on
References
- . Retrieved 24 February 2022.
- ^ "Appendices". cites.org. CITES. Retrieved 14 January 2022.
- ^ a b c "Great Gray Owl". Owl Pages.
- ^ "Great Grey Owl". The Owl Foundation. Species information.
- ISBN 978-0-8493-4258-5.
- ISBN 978-0-7136-6548-2.
- ^ "Strix nebulosa". IUCN Red List of Threatened Species (Report) (Vers. 2013.2 ed.). International Union for Conservation of Nature. 2012.
- S2CID 84375832.
- ^ S2CID 216190368. Retrieved 25 February 2017.
- ^ Master, Larry (22 February 2017). "Great Gray Owls in Northern New York". Adirondack Almanack. Retrieved 25 February 2017.
- ^ "Great Gray Owls". GroWiser.net.
- ISBN 978-0-8018-8687-4.
- ^ König, Claus, Friedhelm Weick, and Jan-Hendrik Becking. Owls of the World. 2nd ed. Bloomsbury Publishing, 2009. Web. 23 May. 2023.
- ^ a b c "Great Gray Owl". Sierra Forest Legacy. Wildlife at risk.
- ^ "Great Gray Owl - Strix nebulosa". The Owl Pages.
- ISBN 1-886614-77-6.
- ^ "Great gray owl". Lindsay Wildlife Experience. Retrieved 7 September 2018.
- ^ "Great Gray Owl". CuriOdyssey. Retrieved 7 September 2018.
- ^ "Boris". Alaska Raptor Center. Retrieved 3 November 2016.
- ^ "Great gray owl, great horned owl, short eared owl". The Alaska Zoo.
- ^ Tudor, Alexander (26 November 2013). "Will Schaff on the artwork for Songs Ohia's Magnolia Electric Co". DrownedInSound.
Other sources
- "Great Gray Owl". Wildlife Species. Interior Timberland Planning, Habitat Conservation Program, Northern Region. Redding, CA: California State Department of Fish and Game. 26 March 2008. Archived from the original on 1 May 2009.
The great grey owl (GGO) was placed on the California state endangered species list in June 1980.
- "Great Gray Owl". Cornell Laboratory of Ornithology. Species Account.
- "Great Gray Owl Information - Strix nebulosa". Patuxent Wildlife Research Center. Bird Identification InfoCenter. USGS.
- "Great Gray Owl". eNature.com. Archived from the original on 15 July 2007.
Further reading
- Lynch, Wayne (2007). Owls of the United States and Canada. Baltimore, MD: Johns Hopkins University Press. ISBN 978-0-8018-8687-4.
- Nero, Robert W. (1980). The Great Gray Owl: Phantom of the northern forest. Washington, DC: Smithsonian Institution.
- Nero, Robert W. (1994). Lady Grayl – Owl with a Mission. Toronto, ON, Canada: Natural Heritage.
- Quinton, Michael S. (July 1984). "The Great Gray Owl". OCLC 643483454.
- Thiemann, Peter J.; Harry Fuller (2015). The Great Gray Owl in California, Oregon, and Washington. Ashland, OR: Nebulosa Press.
External links
- "Species stamps". bird-stamps.org. 7810700. Archived from the original on 2 November 2000.
For Belarus, Finland, Georgia, Ukraine, United States, with world range map.
{{cite web}}
: CS1 maint: unfit URL (link) - "Great grey owl media". Internet Bird Collection.
- Great gray owl photo gallery at VIREO (Drexel University)
- Fuller, Harry (30 June 2016). "Great grey owl range maps for California, Oregon, and Washington". EcoWise (blog) – via wordpress.com.
- "Great Gray Owls (Strix nebulosa)". GroWiser.