The Eurasian eagle-owl (Bubo bubo) is a type of owl that lives across much of Eurasia. It is often called the eagle-owl in Europe and Asia.
This owl is one of the largest owl species. Female Eurasian eagle-owls can grow to about 75 centimeters (30 inches) in length, with a wingspan of 188 centimeters (6 feet 2 inches). Males are slightly smaller. This bird has noticeable ear tufts, with darker blackish and tawny coloring on its upper body. Its wings and tail have dark bars, while its underparts are a mix of light yellowish-brown with darker streaks. Its facial area is not clearly defined, but its orange eyes are a standout feature. At least 12 different types, or subspecies, of the Eurasian eagle-owl have been identified.
Eurasian eagle-owls live in many environments, such as mountainous and rocky areas, near the edges of woodlands, shrubby areas with open spaces, and wetlands. They also live in coniferous forests, open grasslands, and remote regions. Occasionally, they are found in farmland and in city parks in Europe and Asia, though rarely in busy urban areas.
The Eurasian eagle-owl is mainly active at night and hunts small mammals, such as rodents and rabbits, as well as birds and larger mammals. It also eats reptiles, amphibians, fish, large insects, and other small animals.
These owls usually build their nests on cliff edges, in rocky gullies, or in other hidden places. The nest is a simple scrape, where 2 to 4 eggs are laid. The eggs hatch at different times. The female owl stays with the eggs and young, while the male brings food for her and the nestlings. Both parents care for the young for about five months.
The Eurasian eagle-owl is one of the largest owl species and also one of the most widely spread. It lives in an area covering about 51.4 million square kilometers (19.8 million square miles) across Europe and Asia, with an estimated population of 100,000 to 500,000 birds. The International Union for Conservation of Nature (IUCN) lists this species as having the least concern for its survival, though its numbers are slowly decreasing. Most eagle-owls live in Continental Europe, Scandinavia, Russia (where the greatest number and variety of types are found), and Central Asia. Smaller groups also live in Anatolia, the northern Middle East, mountainous regions of South Asia, China, Korea, and Japan. About 12 to 40 pairs of Eurasian eagle-owls live in the United Kingdom, where they may not originally come from. These owls have bred successfully in the UK since at least 1996. Some tame eagle-owls have been used to control pests by scaring away large birds like gulls.
Description
The Eurasian eagle-owl is one of the larger birds of prey. It is smaller than the golden eagle (Aquila chrysaetos) but larger than the snowy owl (Bubo scandiacus), even though there is some overlap in size with both. It is sometimes called the world's largest owl, but Blakiston's fish owl (B. blakistoni) is slightly heavier on average. The great grey owl (Strix nebulosa) is lighter but slightly longer on average. A researcher named Heimo Mikkola found that the largest Eurasian eagle-owls can weigh up to 4.6 kg (10 lb), the same as the largest Blakiston's fish owls. These eagle-owls can also be about 3 cm (1.2 in) longer than Blakiston's fish owls. On average, Blakiston's fish owls are slightly larger in weight and wing size than the biggest Eurasian eagle-owls from Russia. However, the Eurasian eagle-owl can weigh more than twice as much as the largest great grey owls. The Eurasian eagle-owl has a wingspan of 131–188 cm (4 ft 4 in – 6 ft 2 in), with the largest specimens possibly reaching 2 m (6 ft 7 in). Its total length ranges from 56 to 75 cm (22 to 30 in). Female Eurasian eagle-owls weigh between 1.75 and 4.6 kg (3.9 to 10.1 lb), while males weigh between 1.2 and 3.2 kg (2.6 to 7.1 lb). In comparison, the barn owl (Tyto alba), the most widely distributed owl species, weighs about 0.5 kg (1.1 lb), and the great horned owl (B. virginianus), which fills the eagle-owl's role in North America, weighs around 1.4 kg (3.1 lb).
Female Eurasian eagle-owls are larger than males, but there is little difference in appearance between the sexes. Males may have slightly more upright ear tufts than females. When seen alone in the wild, it is usually not possible to tell the sex of an eagle-owl. Sex can be determined by measuring the bird's size in hand. In some populations, females may be slightly darker than males. The plumage color of the Eurasian eagle-owl varies across 13 accepted subspecies. The upper parts are typically brown-black, tawny-buff, or pale creamy gray, with dense freckling on the forehead and crown, stripes on the nape, sides, and back of the neck, and dark splotches on the pale back, mantle, and scapulars. A narrow buff band, freckled with brown or buff, runs from the base of the bill, above the eye, and along the inner edge of the ear tufts. The rump and upper tail feathers have dark, wavy patterns, with the amount of detail varying by subspecies. The underwing and undertail feathers are similar but have more pronounced brownish-black barring.
The primary and secondary feathers are brown with dark brown bars and tips, and grey or buff lines. The Eurasian eagle-owl sheds all its feathers once a year between July and December. Its facial disc is tawny-buff with black-brown speckles, forming a "frame" around the face. The chin and throat are white with a brownish central streak. The upper breast feathers have brownish-black centers and reddish-brown edges, except for the central feathers, which have white edges. The lower breast and belly feathers are creamy-brown to tawny-buff to off-white, with fine dark wavy bars. The legs and feet (feathered almost to the talons) have similar markings but less detail. The tail is tawny-buff with dark grey-brown mottling and about six black-brown bars. The bill and feet are black. The eyes are usually orange, but in some European birds, they are bright reddish-orange. In subspecies living in arid, desert-like areas, the eyes may be orange-yellow. The iris color varies, unlike the Indian eagle-owl, which generally has yellowish eyes.
Standard measurements for the Eurasian eagle-owl include a wing chord of 378 to 518 mm (14.9 to 20.4 in), a tail length of 229–310 mm (9.0–12.2 in), a tarsus length of 64.5–112 mm (2.54–4.41 in), and a bill length of 38.9–59 mm (1.53–2.32 in). The wings are the smallest in proportion to body weight among European owls, with a wing loading of 0.72 g/cm². This means the wings carry more weight compared to their size. The great horned owl has even smaller wings relative to its body size (0.8 g/cm²). The golden eagle has slightly lower wing loading (0.65 g/cm²), so its aerial abilities may not be as different from the eagle-owl as expected. Other owls, such as barn owls, short-eared owls (Asio flammeus), and snowy owls, have lower wing loading, allowing them to fly faster, more agilely, and for longer periods. In the small subspecies B. b. hispanus, the middle claw (the largest talon) measures 21.6 to 40.1 mm (0.85 to 1.58 in). A 3.82 kg (8.4 lb) female in Britain had a middle claw measuring 57.9 mm (2.28 in), similar in length to a large female golden eagle's hallux-claw. Owls generally have smaller talons than birds of prey like hawks but have stronger, more robust feet. Hawks use talons to cause injury, while owls use their feet to constrict prey. The Eurasian eagle-owl's talons are very large and not often exceeded by diurnal raptors. The overall foot strength of the Eurasian eagle-owl has not been tested, but smaller horned owls have one of the strongest grips in birds.
The ear tufts of Spanish Eurasian eagle-owls measure 63.3 to
Taxonomy
The Eurasian eagle-owl was first named by Carl Linnaeus, a Swedish scientist, in 1758 in the tenth edition of his book Systema Naturae. He gave it the two-part scientific name Strix bulbo. Although Linnaeus mentioned the habitat as Europe, the specific location where the species was first identified is Sweden. Today, the Eurasian eagle-owl is placed in the genus Bubo, which was introduced by André Duméril in 1805.
The genus Bubo includes about 10 living species and contains many of the world’s larger owls. Based on fossil evidence and the geographic distribution of modern species, Bubo likely originated in Africa. However, early diversification of the group may have started in southern Asia. Previously, Bubo had more species, but recent genetic studies show that eight former members of the group belong to a related but separate genus called Ketupa, which includes fish owls. Some scientists have considered fishing owls to be part of Bubo, but they are now classified in a different genus called Scotopelia. Two species of scops owls, the giant scops owl (Otus gurneyi) in Asia and the white-faced scops owl (Ptilopsis) in Africa, share some traits with eagle-owls despite being in the scops owl group. The Strix genus is also related to Bubo and is considered a "sister complex" with Pulsatrix possibly being a link between the two. The Eurasian eagle-owl appears to have expanded the Bubo genus into Eurasia. Some species in Bubo may have evolved from the Eurasian eagle-owl, making it a "paraspecies" or sharing a recent common ancestor with them.
The Pharaoh eagle-owl, found in the Arabian Peninsula and parts of North Africa with rocky areas, was once considered a subspecies of the Eurasian eagle-owl. Genetic differences in mitochondrial DNA show the Pharaoh eagle-owl differs by about 3.8% from the Eurasian eagle-owl, which is more than the 1.5% needed to classify as a separate species. The Pharaoh eagle-owl is smaller and paler, with a higher-pitched call. Eurasian eagle-owls in Morocco did not breed with Pharaoh eagle-owls, but those in the Middle East (subspecies B. b. interpositus) can interbreed with them. Genetic tests also suggest B. b. interpositus might be a distinct species, differing from the Eurasian eagle-owl by 2.8% in mitochondrial DNA. Three Asian subspecies of the Eurasian eagle-owl meet subspecies criteria, showing high genetic diversity despite a recent common ancestor. The Indian eagle-owl (B. bengalensis) was once considered a subspecies but is now classified as a separate species due to its smaller size, distinct call, and geographic separation from Eurasian eagle-owls. Its mitochondrial DNA also differs significantly from the Eurasian eagle-owl. The Cape eagle-owl (B. capensis) appears to be a return of this genetic line to Africa, where it lives similarly to Eurasian eagle-owls but farther south. Another offshoot of the Bubo group is the snowy owl, which separated from other Bubo species at least 4 million years ago.
The fourth major evolutionary branch from the group that includes the Eurasian eagle-owl is the great horned owl, which likely spread from Eurasia to North America. Some scientists say the great horned owl and Eurasian eagle-owl are barely distinct as species, similar to the differences between Eurasian and North American populations of other owls. However, the great horned owl is physically different, being smaller, with horizontal underparts, yellow eyes, and a more defined facial disc. Genetic research shows the snowy owl is more closely related to the great horned owl than to the Eurasian eagle-owl. The African spotted eagle-owl (B. africanus), smaller and less powerful, is the closest relative to the Eurasian eagle-owl beyond the Pharaoh, Indian, and Cape eagle-owls. Genetic evidence suggests the spotted eagle-owl shares a more recent ancestor with the Indian eagle-owl than with the Eurasian or Cape eagle-owl. Eurasian eagle-owls in captivity have produced hybrids with both the Indian eagle-owl and the great horned owl. The Pharaoh, Indian, and Cape eagle-owls, as well as the great horned owl, are all similar in size but smaller than the Eurasian eagle-owl, which is 15–30% larger in length and 30–50% heavier. This size difference may be due to adaptations to warmer climates and smaller prey. Fossils from southern France show that during the Middle Pleistocene, Eurasian eagle-owls were larger than they are today. Even larger fossils from Azerbaijan and the Caucasus, dating to the Late Pleistocene, suggest they were even bigger. Today, about 12 subspecies of the Eurasian eagle-owl are recognized.
Habitat
Eagle-owls are not found in many places, but they can live in various types of habitats, especially in areas with uneven land. They have been found in places like northern forests, near the edges of large deserts, and almost everywhere on the Eurasian continent except for two areas: the humid rainforests of Southeast Asia and the high Arctic tundra. In these other areas, other owl species often live instead. Eagle-owls are most commonly found in places where cliffs and valleys are surrounded by scattered trees and bushes. They can also live in grassy areas like alpine meadows or desert-like steppes, as long as there are rocky areas to provide cover. Studies show that eagle-owls prefer uneven land because nesting and resting spots in rocky or steep areas are harder for predators, including humans, to reach. They may also live near rivers or wetlands because soft soil in these areas helps small animals like voles and rabbits dig burrows, which are their main food sources.
Eagle-owls often live in mountainous areas and can be found at high elevations, such as 2,100 meters (6,900 feet) in the Alps, 4,500 meters (14,800 feet) in the Himalayas, and 4,700 meters (15,400 feet) on the Tibetan Plateau. They can also live at sea level, nesting on rocky seaside cliffs. Even though they live in cold places like subarctic zones and mountains, studies in Germany show that they breed more successfully in warmer areas. In Spain, eagle-owls prefer areas with forests, especially pine trees, over mixed pine and oak woodlands. They are usually found near the edges of forests, not in dense woods like the tawny owl. Only 2.7% of the areas where eagle-owls live in Spain are farmland. Compared to golden eagles, eagle-owls visit farmland more often because they hunt at night and avoid human activity. They are more likely to live on farmland that is not heavily farmed, has many trees and bushes, and has little irrigation. Farmland with unused or abandoned fields often has more prey and less human activity. In the Italian Alps, eagle-owls have nested near towns, villages, and ski resorts because little natural habitat remains there.
Although eagle-owls are most common in areas with few people, they sometimes live on farmland and even in quiet, park-like areas in cities. Since 2005, at least five pairs of eagle-owls have nested in Helsinki, Finland. This is partly because feral European rabbits, which were originally released from pets, have become common in the area. The number of eagle-owls is expected to grow as the rabbit population increases. European hares, which are often the main prey of eagle-owls, live only in rural areas of Finland, not in city centers. In June 2007, an eagle-owl named "Bubi" landed in the crowded Helsinki Olympic Stadium during a football match between Finland and Belgium. The game was paused for six minutes before the bird left. Finland’s national football team has since been nicknamed "Huuhkajat," which means "Eurasian eagle-owls" in Finnish. The owl was named "Helsinki Citizen of the Year" in 2007. In 2020, an eagle-owl raised three chicks in a large, leafy planter on an apartment window in Geel, Belgium.
Distribution
The Eurasian eagle-owl lives in many places around the world, but it does not cover as much area as the short-eared owl or long-eared owl. It also does not live in all areas around the North Pole like some other owls, such as the great grey owl or boreal owl. This owl is found in the westernmost parts of the Iberian Peninsula, mostly in Spain and in some areas of Portugal. From there, it lives in parts of southern France, from Toulouse to Monaco, and as far north as the Allier region. It also lives in Luxembourg, southern and western Belgium, and most of the Netherlands. It is rarely seen in southern and central parts of the United Kingdom. In Germany, the owl lives in large areas, but these areas are not connected and are mostly in the south and central parts. It is almost never found in places like Brandenburg. From Germany, the owl’s range continues into the Czech Republic, Slovakia, northern and eastern Hungary, and some parts of Poland. In mountainous countries like Switzerland and Austria, the owl lives in many areas. In Italy, the owl is found in the northern, western, and central parts, as far south as Melito di Porto Salvo. From Italy, the owl lives along the Mediterranean coast in Southeastern Europe, from Slovenia to most of Greece and Bulgaria. In eastern Europe, the owl is found throughout central Romania to Estonia. It also lives in most of Finland and Scandinavia, with the largest numbers in Norway, fewer in Sweden, and mostly in Jutland, Denmark, but not on the islands.
In Russia, the Eurasian eagle-owl lives in a very large area, avoiding only the true Arctic zone, where trees do not grow. It is likely the owl species that lives in the most places in Russia. From Russia, the owl lives in Central Asia, continuously from Kazakhstan to Afghanistan. In Asia Minor, it lives in Georgia, Azerbaijan, and parts of western and southern Turkey, but its presence is not common in Turkey overall. In the Middle East, the owl is found in small areas of Syria, Iraq, Lebanon, Israel, Palestine, Jordan, and western Iran, but it is more common in northern and western Iran. In South Asia, the owl is often found in northern Pakistan, northern Nepal, and Bhutan, and less often in northern India. The owl lives in Mongolia and most of China, except in southern Yunnan and southern Guangxi. From China and eastern Russia, the owl is found in Korea, Sakhalin, the Kuril Islands, and rarely in northern Hokkaido, Japan. The farthest east the owl lives is in Magadan, Russia.
Behaviour
The Eurasian eagle-owl is mostly active at night, like most owls. It is most active in the first few hours after sunset and the last few hours before sunrise. In the northern parts of its range, it sometimes hunts during the late afternoon, even in daylight. This happens because, during summer, there is very little darkness at the peak of the season, so the owls must hunt and care for their young during the day.
The Eurasian eagle-owl makes different sounds at different times. It often uses high places like rocky hills, ridges, or mountain peaks as song posts. These spots are located at the edges of its territory and are visited briefly but frequently.
Most of its vocal activity happens during the colder months, from late fall through winter. In October through December, the sounds are used to mark territory, while in January through February, they are used for courtship and mating. A study in Spain found that these sounds begin no earlier than 29 minutes after sunset and end no later than 55 minutes before sunrise. The male’s territorial call is a deep, resonant "ooh-hu," while the female’s is a higher-pitched "uh-hu." Sometimes, pairs sing together in a duet. In Germany and parts of Europe, the owl is called "uhu" because of its call. The Eurasian eagle-owl’s territorial call is deeper and carries farther than the calls of the great horned owl or Blakiston’s fish owl. Other sounds include a faint, laughing "OO-OO-oo," a harsh "kveck-kveck," and a loud "hooo" when threatened. It also makes deep, powerful barks similar to those of other owl species. When annoyed, it may click its beak or spit like a cat, and it may lower its head, puff up its feathers, fan its tail, and spread its wings to appear larger.
The Eurasian eagle-owl rarely stands upright with its feathers pressed close to its body, a posture called the "tall-thin position." This behavior is more common in other owls, like the long-eared owl. The Eurasian eagle-owl flies with strong, direct movements, using shallow wing beats and long glides. It is unusual for an owl to soar on updrafts, which has led to confusion with Buteos, a different type of bird. During the day, it is often seen flying because it has been disturbed by humans or other animals. The Eurasian eagle-owl does not migrate, unlike the snowy owl. Even in northern areas with harsh winters, it stays in its home range. A 2020 study found that some adult owls move up to 20 km (12 mi) from their nests in the fall after breeding. There are unverified reports of some Eurasian eagle-owls moving south in Russia or Tibet during winter, but there is no evidence of regular migration. These birds can survive on their usual territories even in difficult conditions.
Breeding
Eurasian eagle-owls are very protective of their territories and will fight to keep other eagle-owls away all year long. However, they call out to defend their areas most often between October and February. Their territories are about the same size as those of great horned owls, ranging from 15 to 80 km (5.8 to 30.9 sq mi). Males choose the highest spots in their territory to sing, as this helps their calls be heard farther and reduces the need for physical fights near territory borders. The white patch on their throat is also important for showing territory. When scientists placed stuffed owls with flared white throats near eagle-owl territories, male owls reacted strongly and sometimes attacked them. Female owls were less likely to attack stuffed owls, whether or not their throats were flared.
In January and February, eagle-owls use calls mainly for courtship. Most eagle-owls stay with the same partner for life but perform courtship rituals each year to strengthen their bond. During courtship, males bow and hoot loudly but do so in a less exaggerated way than great horned owls. Courtship may include "duetting," where the male sits upright and the female bows while calling. Sometimes, both owls bow, touch beaks, or groom each other before the female flies to a perch where they mate, usually several times over a few minutes.
Males choose nesting sites and show them to females by flying to them and making small depressions in the ground (if soil is present) while making short, quick sounds. The female then picks one site. In Baden-Württemberg, Germany, males spend more time visiting nesting sites as the breeding season nears, increasing from about 29 minutes to 3 hours. Males also sit on the eggs during incubation. Unlike other owls, Eurasian eagle-owls do not build nests but use existing structures like rocks, cliffs, or caves. They often nest on rocky areas, cliff edges, or steep slopes, and sometimes on the ground near trees or under bushes. In some areas, like Russia’s Altai Krai, they nest on the ground at the base of pine trees. They rarely use nests built by other birds, but in some places like Belarus, they may use nests from storks or eagles. Tree holes are used very rarely. Eurasian eagle-owls often return to the same nest each year.
In the Engadin region of Switzerland, the male hunts alone until the young are 4 to 5 weeks old, while the female stays at the nest to care for the eggs. After this, the female and young begin hunting, providing more food. Though they are usually territorial, there are rare cases where a male has mated with two females or a third adult has helped care for the young. Eurasian eagle-owls are generally less aggressive toward humans than other owls. If a human approaches a nest, the female may sometimes pretend to be injured to distract them, though this is uncommon. More often, the owls stay away from the nest, which is well-hidden. If cornered, adults or young may spread their wings and puff up their feathers to threaten humans, a rare behavior in owls. Some eagle-owls in Britain and Scandinavia may act more aggressively near nests, though this is not common.
Eurasian eagle-owls lay eggs every three days, and the female incubates them alone. Egg-laying usually starts in late winter but may be later in colder areas. The male brings food to the female during incubation. Each egg is white and measures about 56 to 73 mm (2.2 to 2.9 in) in length and 44.2 to 53 mm (1.74 to 2.09 in) in width, weighing around 75 to 80 g (2.6 to 2.8 oz). In Central Europe, eggs average 59.8 mm × 49.5 mm (2.35 in × 1.95 in), and in Siberia, 59.4 mm × 50.1 mm (2.34 in × 1.97 in). Clutch sizes are usually one or two eggs, sometimes three or four, and rarely up to six. The number of eggs depends on the location, with more eggs laid in southern regions.
Status
The Eurasian eagle-owl lives in many parts of Europe and Asia, covering an area about 32,000,000 km² (12,000,000 mi²). In Europe alone, there are between 19,000 and 38,000 pairs of eagle-owls that breed each year. Worldwide, there are an estimated 250,000 to 2,500,000 individual birds. Scientists believe the population is decreasing because of human activities, but because the bird has a large range and large numbers, the International Union for Conservation of Nature lists it as "least concern" for conservation. The great horned owl, which lives in North America, has a population of up to 5.3 million individuals, which is about twice the number of Eurasian eagle-owls. This difference may be due to factors such as less harm from humans, better ability to live in less ideal habitats, and smaller territories. Eurasian eagle-owls are protected by CITES, which means international trade in their parts is controlled.
Eurasian eagle-owls are among the longest-living owls. They can live up to 20 years in the wild. One eagle-owl lived to be 27 years and 9 months. In captivity, they may live even longer, up to 68 years. Healthy adult eagle-owls have no natural predators and are considered top predators. The main causes of their deaths are human-related, such as electrocution, traffic accidents, and being shot.
Electrocution is the leading cause of death for eagle-owls, according to 68% of studies. In some areas, like the Italian Alps, many eagle-owls die from contact with uninsulated power poles near their nests. In one study, 55% of young eagle-owls released from captivity died from electrocution within a year. In the Swiss Rhine Valley, some released eagle-owls died from starvation, but most wild eagle-owls found dead were due to human causes, like electrocution or collisions with vehicles. Insulating power poles may help stabilize local populations by allowing other eagle-owls to move into empty territories. In Finland, electrocution and vehicle collisions are the main causes of eagle-owl deaths. Wind turbines can also be dangerous to eagle-owls in some areas.
Historically, eagle-owls have been hunted because they were thought to harm game animals, which affected people who rely on hunting. This led to their local extinction in places like northern Germany, the Netherlands, Luxembourg, Belgium, and parts of Germany in the 1960s. In Spain, studies found that 411 eagle-owls died from collisions, mostly electrocution, and 313 were killed by humans. Persecution remains a major problem for eagle-owls in Spain and France.
Eagle-owls are still common in areas with little human activity, such as parts of Russia and Scandinavia. However, in Western and Central Europe, where human activity is high, eagle-owls face dangers like collisions with power poles and loss of prey due to habitat changes.
In Spain, government protection has not reduced the killing of eagle-owls by people. Conservationists suggest improving education and community programs to stop direct harm to eagle-owls. Scientists recommend insulating power lines and poles to reduce electrocution, but this is costly and has been done little in areas with limited funding. In Sweden, a project to insulate transformers has been started.
In Germany, eagle-owls were reintroduced after they disappeared in the 1960s due to hunting. Over 1,000 eagle-owls were released in the Eifel region, but their survival rates are still low because of human-related causes. Some worry about low genetic diversity in these reintroduced populations. Eagle-owls from Germany have helped repopulate nearby countries like the Netherlands, Belgium, and Luxembourg. In Sweden, current populations are likely due to reintroductions.
Eagle-owls have also benefited from non-native prey, such as rats and pigeons, which are common in human areas. These prey species provide food, allowing eagle-owls to live in places where they were once rare.
The Eurasian eagle-owl once lived naturally in Great Britain. Some believe it disappeared about 10,000–9,000 years ago after the last ice age. However, fossil evidence from Meare Lake Village suggests it may have lived there longer.