Great grey owl

Most common in northern Sweden

The great grey owl nests in the northernmost coniferous forest areas (the taiga) of Europe, Asia and North America. In Sweden, it is found down as far as Jämtland, but is most common in the woodlands of Norrbotten and Västerbotten and along the Norrland coast. It is usually found near marshland or other open areas such as meadows and clearings, where it can hunt small rodents.

The great grey owl lives in the wilderness and thrives in old spruce, pine and bog pine forests, as well as in mountain birch forests.

Small territories

Great grey owls can have small territories, and two nests can often exist within 100 metres of each other. They are non-migratory, but may sometimes move south, east and west if voles becomes scarce where they live. They usually survive even when food is scarce, but they need plenty of food to nest and raise their young. The number of great grey owls changes from year to year, as the number of small rodents varies significantly.

Does not build its own nest

The great grey owl is completely unable to build its own nest. Instead, it nests in twig nests built by other birds such as buzzards and goshawks. If there are no empty nests available, they can nest on high stumps, hunting towers, anthills or uprooted trees.

Adapted to a cold climate

The great grey owl is one of Sweden’s largest owls, but its size is partly an illusion due to its fluffy plumage, with a male weighing no more than 1 kilogram and a female 1.5 kilograms. When frightened, it shrinks to look like a narrow branch.

The most distinctive feature of the species is its large head, which can have a circumference of 50 cm. The great grey owl is adapted to a cold climate, and its plumage provides excellent protection against the cold. Its legs and feet are also feathered all the way down to its toes.

Its wingspan is roughly 130–150 cm, and its body is about 60–70 cm long. Typical features are a thick neck and a very large, round head, which appears sharply cut-off in profile. The great grey owl’s large face makes it very good at picking up sounds.

Flies silently

The owl beats its wings slowly as it flies. The female is larger than the male, and both have large ash-grey rings around their small, yellow eyes. The plumage is ash grey, with white and dark markings on the upper side and a distinctly striped underside. Its tail is long and greyish-brown with a dark, broad band at the base, which distinguishes it from the Ural owl. When the male flies, orange-brown markings can be seen on its wings. Like all owls, the great grey owl can fly almost silently thanks to the structure of its wing feathers.

Locates prey by hearing

The great grey owl feeds mainly on voles and shrews. Like other owls, it eats small rodents whole and then vomits up the bones and fur, which it cannot digest, in the form of owl pellets.

The great grey owl sees extremely well in the dark. It hunts using both sight and hearing, and can hear a mouse even through a thick covering of snow. Owls’ ears are at different heights, allowing the bird to locate its prey precisely by moving its head. It also has feathered skin flaps behind the ear openings, enabling the bird to vary the size of its ear opening in order to locate its prey more accurately.

The great grey owl is most active and mainly hunts at dawn and dusk. However, it can also be active during the day, and even hunts during light summer nights.

Lifelong pairings

Great grey owls live in pairs throughout their entire lives. Together, they take over old buzzard or goshawk nests or nest on top of a high stump. The mating season begins in mid-February, and in April or May the female usually lays two to four oval eggs, and sometimes as many as nine. The female sits on the eggs for 28 to 30 days, and the chicks weigh about 40 grams when they hatch. It is the male who catches food for the female during incubation, and then for the chicks when they are young. After that, both parents help to catch prey.

The chicks leave the nest after a month, but then it takes a few more weeks before they are ready to fly. The chicks are olive-brown with white patches to begin with. They then grow their adult feathers at the age of about five months. Once the chicks have hatched, the female becomes highly aggressive and immediately attacks intruders with both her claws and her wing knuckles. At other times of the year, the owl is peaceful and is often unafraid of humans.

Threatened by logging and poaching

The most serious threat to the great grey owl is a loss of habitat due to logging. Other threats include poaching and trading in endangered and rare birds and their eggs. The number of great grey owls can vary between about 500 and 2,000, depending on access to food and breeding success.

The great grey owl is classified as ‘Vulnerable’ on the Swedish Species Information Centre’s red list.