Great Gray Owl (Strix nebulosa)

great gray owl

The great gray owl, also known as the great grey owl or Strix nebulosa, is a large owl native to the Northern Hemisphere. The great gray owl was first described by Carl Linnaeus in 1758 and can also be referred to as the great grey owl, giant owl, or Arctic owl, but this species is only distantly related to other gray owls such as the spotted owl (Strix occidentalis).

In addition to being one of the largest and most powerful owl species, it is one of the most widespread raptors in the world.

It has long ear tufts and yellow eyes with black pupils and it has gray plumage with white underparts and flight feathers on its wings that appear frosted as seen from a distance.

Because of their large size and relatively low population compared to other owl species, great gray owls are not commonly kept as pets; however, there are many organizations that rehabilitate injured wild owls and release them back into the wild once they have fully recovered.


great gray owl

Native to North America, the great gray owl is found in a range of habitats from humid temperate forests to Arctic tundra. This large bird can weigh up to three pounds and grow up to four feet tall.

They have beautiful dark eyes and markings on their chest that vary from white, orange, or yellow. Great gray owls have feathers that appear dense and soft because they are not as fluffy as many other types of owls’ feathers.

Scientific name

The scientific name of the great gray owl is Strix nebulosa

Great gray owl habitat

Great gray owls live in North America. They mainly reside in the boreal forest of Canada and Alaska, but are also seen in some parts of the United States. The owl’s habitat is vast as they can be found in forests, on prairies, around lakes, and near rivers.

North Island Brown Kiwi (Apteryx mantelli)

As a result of their vast territory, Great gray owls have also been observed living close to human populations which sometimes has negative consequences. For example, humans often think that when they see an owl it is an omen of death or something bad happening.

These misconceptions lead to many birds being killed by people out of fear that the animal will bring bad luck upon them or others. There are many misconceptions about this bird because of its dark plumage and silent flight that causes people to fear it even though it poses no serious threat to humans.

Great grey owl size

The great grey owl wingspan can reach up to 135 to 153 cm (53 to 60 inches), and its body length can reach up to 61 to 86 cm (24 to 34 inches) long. The great grey owl weight is around 20.5 to 67 oz (580 to 1900 g), making them one of the biggest species of owl on Earth.

Great grey owl feathers and plumage

great gray owl

This owl has feathers that are dark brown and a face that is tawny-brown. They have white patches on their breast, back, and belly. The females can be distinguished from the males by their lighter coloration. In addition to wings, they also have long, fluffy tail feathers.


Throughout the year, birds shed and grow new feathers. The process is called molting. Great gray owls typically molt once a year for about four months, starting in May or June. At the same time, they are building up enough energy reserves to last them through the winter season of nocturnal hunting.

As they prepare to molt, they begin to eat more food than usual, anything from small mammals and carrion to insects and fish, to fuel their migration southwards for better habitat during the cold winter months.

Long Eared Owl Bird (Asio otus)

During this process, great gray owls usually lose weight, making it easier for them to fly across large bodies of water on their way southward where there will be fewer natural predators like eagles and hawks. It can take a few weeks before they have completely replenished their body weight, so while they are migrating they need to find prey every day.

When they migrate back northward after the winter, they will again try to build up sufficient fat reserves by eating as much as possible along the way so that when they return home again in late April or early May, the cycle can repeat itself!

Diet and foraging

They tend to prey on small mammals. In many northern areas, they feed mainly on voles; pocket gophers are common prey in the western U.S. They eat mice, shrews, squirrels, weasels, small birds, and rare frogs.

They prefer to hunt prey that weighs less than 450 grams but can kill prey that weighs up to 900 grams. If a great gray owl is unable to find enough prey it will feed on birds, fish, reptiles, and amphibians. Great gray owls have also been known to occasionally attack young porcupines.

Great gray owl sounds and vocal behavior

A series of resonating hoots are emitted during the breeding season (roughly between March and July), each lasting about 6 to 8 seconds, followed by about 30 seconds of silence. Compared to females, males have a lower pitch when they vocalize.
A soft double hoot can also be made by adults during territorial defense or food delivery.


great gray owl

Great gray owls form pairs and are monogamous. March through May are the most popular times for nesting. Due to the fact that they do not build nests, they typically use nests that have been used by larger birds, such as raptors.

A broken-topped tree or a cavity in a large tree will also be a suitable nesting place for them. Females lay four eggs and incubate them for 28 to 36 days. Hatched great grey owl babies are helpless and blind.

Morepork Owl (Ninox novaeseelandiae)

The female roosts on a tree near nests after brooding for 2 to 3 weeks. 3 to 4 weeks after hatching, great grey owl babies jump or fall from the nest, and one to two weeks later they start to fly.

A white, fuzzy great grey owl baby must climb back into a tree immediately after fledging using its beak and feet. It is possible for the female great grey owl to become aggressive at this time in response to a potential predator.

In the months following fledging, many young great grey owl babies stay close to their natal sites. Males normally hunt for their mate and are young throughout the nesting season.

It is common for the female to withdraw once the young begin to fly and the male to continue to feed them until they can hunt independently in the autumn. As winter approaches, great grey owl babies become independent.


The lifespan of the great gray owl ranges from 15 years in the wild to 27 years in captivity, with an average of 22 years.

Diseases and threats

The great gray owl has many natural predators, including bobcats, owls, and hawks. Additionally, domestic cats in particular are known to be an especially significant predator of the species.

Oftentimes, these threats can lead to injuries or even death to the great gray owl. For example, one study found that 81% of 401 confirmed great gray owl fatalities were due to predation by bobcats or feral house cats and 11% were due to collisions with man-made objects such as fences or automobiles.

Population status

Approximately 50,000 to 99,999 mature Great gray owls are recorded on the IUCN Red List. Its status on the IUCN Red List is Least Concern (LC), and its numbers are increasing every year.

Conservation and management

The great gray owl is classified as a species of Least Concern. The main threats to their population are habitat loss, competition with humans for food and nesting sites, and small population size.

Whippoorwill Bird (Caprimulgus vociferus)

However, they inhabit the widest range of habitats in North America, so this shouldn’t be a cause for concern.

However, there are conservation efforts to help the population grow again such as habitat preservation and feeding stations. The great gray owl is listed as a Species of Concern by both the U.S. Fish and Wildlife Service and Canada’s Committee on the Status of Endangered Wildlife in Canada because they require large habitats with many nest sites, abundant prey populations for hunting, and no human disturbance.

The American Ornithologists Union recognizes this species as a member of its Near Threatened category. It was formerly classified as Least Concern but that classification was dropped when the population declined more than 30% over 10 years ago.

In some parts of North America, it has become extirpated or even locally extinct.

It faces threats from deforestation, forest fragmentation, climate change, and other natural causes; humans pose an increasing threat due to the destruction of forests through logging, and the expansion of towns and cities into wilderness areas and roadsides leading to higher mortality rates from collisions with vehicles.