Great Grey Owl
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The great grey owl (''Strix nebulosa'') (also great gray owl in
American English American English, sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. English is the Languages of the United States, most widely spoken lang ...
) is a
true owl The true owls or typical owls (family (biology), family Strigidae) are one of the two generally accepted families of owls, the other being the barn owls and bay owls (Tytonidae). This large family comprises 230 living or recently extinct species ...
, and is the world's largest species of owl by length. It is distributed across the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
, and it is the only species in the genus '' Strix'' found in both Eastern and Western Hemispheres. In some areas it is also called the Phantom of the North, cinereous owl (this name is also used for '' Strix sartorii''), spectral owl, Lapland owl, spruce owl, bearded owl, and sooty owl.


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 In ornithology, the facial disc is the concave collection of feathers on the face of some birds—most notably owls—surrounding the eyes. The concavity of the facial disc forms a circular paraboloid that collects sound waves and directs those ...
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 The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl, a type of bird that resides in much of Eurasia. It is often just called the eagle-owl in Europe and Asia. It is one of the largest species of owl. Females can grow to a total le ...
and the
Blakiston's fish owl Blakiston's fish owl (''Ketupa blakistoni''), the largest living species of owl, is a fish owl, a sub-group of eagle-owls that specialize in hunting in riparian areas. It is native to China, Japan, and the Russian Far East. This species is a p ...
as the world's largest owl. The great grey is outweighed by those two species as well as several others, including most of the genus ''
Bubo A bubo (Greek βουβών, ''boubṓn'', 'groin') is adenitis or inflammation of the lymph nodes and is an example of reactive infectious lymphadenopathy. Classification Buboes are a symptom of bubonic plague and occur as painful swellings in ...
''. 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 , averaging for females and for males. The wingspan can exceed , but averages for females and for males. The adult weight ranges from , averaging for females and for males. The males are usually smaller than females, as with most owl species. 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. * ''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
conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...
ous forests of the
taiga Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. In North A ...
, 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 .


Range

They breed in
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
from as far east as
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
to the
Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...
coast and
Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
, and from
Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
and
Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...
across northern
Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...
. 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. 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 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''). 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 Park Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...
s. 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
New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...
and
New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...
, apparently in pursuit of more abundant prey. Great grey owls are rarely sighted as far south as
Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...
and
Long Island, New York Long Island is a densely populated continental island in southeastern New York (state), New York state, extending into the Atlantic Ocean. It constitutes a significant share of the New York metropolitan area in both population and land are ...
. In winter 2017, the birds were recorded in northern New York in Robert Moses State Park and central
Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...
.


Breeding

Great grey owls do not build nests, so they typically use nests previously used by a large bird, such as a raptor. They will also nest in broken-topped trees and cavities in large trees. In southwestern and northeastern Oregon, the great grey owl has been using man-made platforms for nest sites since the 1980s. The erection of nest platforms for great grey owls was pioneered by Robert Nero in central Canada in the 1970s. Nesting may occur from March to May. Unlike, for example, osprey or white storks, the great grey owl does not predictably re-use nest sites over consecutive years. Four eggs are the usual clutch size. Eggs average wide and long. The incubation period is about 30 days, ranging from 28 to 36 days. Brooding lasts 2 to 3 weeks, after which the female starts roosting on a tree near nests. The young jump or fall from the nest at 3 to 4 weeks, and start to fly 1 to 2 weeks after this. Immediately after fledging, the white, fuzzy young must use beak and feet to climb back into trees. The female is on guard at this time and may be aggressive toward potential predators. Most offspring remain near their natal sites for many months after
fledging Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...
. Normally the male hunts for his mate and the young throughout the nesting period. Once the young begin the fly, the female typically withdraws and the male continues to feed the young until they can hunt on their own in the autumn. The young owls go off on their own by winter. 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 Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
, 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 The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air") or the hoot owl, is a large owl native to the Americas. It is an extreme ...
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.


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 disc In ornithology, the facial disc is the concave collection of feathers on the face of some birds—most notably owls—surrounding the eyes. The concavity of the facial disc forms a circular paraboloid that collects sound waves and directs those ...
s, 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 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 '' Strix'' are known to "snow-plunge" for prey, a habit that is thought to require superb hearing not possessed by all types of owls. Unlike the more versatile eagle and horned owls, great grey owls rely almost fully upon small
rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
s. What species they eat depends on which small mammals are most abundant and available. In northern Canada and other parts of Scandinavia, they eat
lemming A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which form part of the superfamily Muroidea, which also inclu ...
s primarily. In dry parts of California's Sierra Nevada they eat mostly
pocket gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They ar ...
s. In some areas
vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...
s are the predominant prey. Locally, alternative prey animals (usually comprising less than 20% of prey intake) include
squirrel Squirrels are members of the family Sciuridae (), a family that includes small or medium-sized rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrel ...
s,
hare Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores and live Solitary animal, solitarily or in pairs. They nest in slight depressions called forms, and their young are precociality, able to fend for themselves ...
s,
mole Mole (or Molé) may refer to: Animals * Mole (animal) or "true mole" * Golden mole, southern African mammals * Marsupial mole Marsupial moles, the Notoryctidae family, are two species of highly specialized marsupial mammals that are found i ...
s,
shrew Shrews ( family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to dif ...
s,
weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets, and European mink. Members of this genus are small, active predators, with long and slend ...
s, thrushes,
grouse Grouse are a group of birds from the order (biology), order Galliformes, in the family (biology), family Phasianidae. Grouse are presently assigned to the Tribe (biology), tribe Tetraonini (formerly the subfamily Tetraoninae and the family Tetr ...
, Canada jays,
mountain quail The mountain quail (''Oreortyx pictus'') is a small ground-dwelling bird in the New World quail family (biology), family. This species is the Monotypic, only one in the genus ''Oreortyx'', which is sometimes included in ''Callipepla''. This is n ...
, small
hawk Hawks are birds of prey of the family Accipitridae. They are very widely distributed and are found on all continents, except Antarctica. The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks, and others. This ...
s,
duck Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...
s,
frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...
s and large
beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s. This species is not known to scavenge or steal from other predators. In mated pairs, the male is the primary hunter who provides food for the entire family while the female guards and broods the eggs, nestlings, and flightless fledglings.


Threats

The harvest of
timber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...
from the great grey owl's habitat is, perhaps, the greatest threat to this species. Intensified timber management typically reduces live and dead large-diameter trees used for nesting, leaning trees used by juveniles for roosting before they can fly, and dense canopy closures in stands used by juveniles for cover and protection. If perches are not left in clearcuts, great grey owls cannot readily hunt in them. Although human-made structures (made specifically for use by this species) have been utilized by these owls, the species is far more common in areas protected from logging. Livestock grazing in meadows also adversely affects great grey owls, by reducing habitat for preferred prey species. Other dangers to great grey owls include rodenticides, collisions with vehicles, and the
West Nile Virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family ''Flaviviridae'', from the genus ''Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The virus ...
. The West Nile virus is likely to become more prevalent with climate change. In Ontario and northeastern Oregon there are confirmed great grey owl deaths from the virus. Testing of owls in the Yosemite area since 2005 has found evidence of the virus in that population. Due to their large size, great grey owls have few natural predators.
Great horned owl The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air") or the hoot owl, is a large owl native to the Americas. It is an extreme ...
s, 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. The only known predator of adult great grey owls is the
Eurasian eagle-owl The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl, a type of bird that resides in much of Eurasia. It is often just called the eagle-owl in Europe and Asia. It is one of the largest species of owl. Females can grow to a total le ...
(''Bubo bubo''), which occasionally preys on the former in parts of Europe.


Territorial behavior

The great grey owl is not as aggressive as most other
apex predator An apex predator, also known as a top predator or superpredator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the hig ...
s. 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 Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...
, Canada.


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, and the fourth lives at CuriOdyssey in San Mateo, California. 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. 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. 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 William Schaff's album art for '' The Magnolia Electric Co.'', a 2003 alt-country album by Songs: Ohia.


References


Other sources

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Further reading

* * * * *


External links

* * * * * {{Authority control
great grey owl The great grey owl (''Strix nebulosa'') (also great gray owl in American English) is a true owl, and is the world's largest species of owl by length. It is distributed across the Northern Hemisphere, and it is the only species in the genus ''Str ...
Holarctic birds Birds of Manchuria Provincial symbols of Manitoba
great grey owl The great grey owl (''Strix nebulosa'') (also great gray owl in American English) is a true owl, and is the world's largest species of owl by length. It is distributed across the Northern Hemisphere, and it is the only species in the genus ''Str ...
great grey owl The great grey owl (''Strix nebulosa'') (also great gray owl in American English) is a true owl, and is the world's largest species of owl by length. It is distributed across the Northern Hemisphere, and it is the only species in the genus ''Str ...