Instruct: Given a question, retrieve documents that answer the question.
Query: Where can you find a Eurasian eagle-owl?
With a total range in Europe and Asia of about 32 million square kilometres (12 million square miles) and a total population estimated to be between 250 thousand and 2.5 million, the IUCN lists the bird's conservation status as being of "least concern".[8] The vast majority of eagle-owls live in mainland Europe, Russia and Central Asia, and an estimated number of between 12 and 40 pairs are thought to reside in the United Kingdom as of 2016, a number which may be on the rise.[9] Tame eagle-owls have occasionally been used in pest control because of their size to deter large birds such as gulls from nesting.[10]
The male selects breeding sites and advertises their potential to the female by flying to them and kneading out a small depression (if soil is present) and making staccato notes and clucking noises. Several potential sites may be presented, with the female selecting one.[14] Like all owls, Eurasian eagle-owls do not build nests or add material but nest on the surface or material already present. Eurasian eagle-owls normally nest on rocks or boulders, most often utilizing cliff ledges and steep slopes, as well as crevices, gullies, holes or caves. Rocky areas that also prove concealing woodlots as well as, for hunting purposes, that border river valleys and grassy scrubland may be especially attractive.[6][69] If only low rubble is present, they will nest on the ground between rocks.[14] Often, in more densely forested areas, they’ve been recorded nesting on the ground, often among roots of trees, under large bushes and under fallen tree trunks.[6] Steep slopes with dense vegetation are preferred if nesting on the ground, although some ground nests are surprisingly exposed or in flat spots such as in open spots of the taiga, steppe, ledges of river banks and between wide tree trunks.[14] All Eurasian eagle-owl nests in the largely forested Altai Krai region of Russia were found to be on the ground, usually at the base of pines.[70] This species does not often use other bird’s nests as does the great horned owl, which often prefers nests built by other animals over any other nesting site.[6] The Eurasian eagle-owl has been recorded in singular cases using nests built by common buzzards (Buteo buteo), golden eagle, greater spotted (Clanga clanga) and white-tailed eagles (Haliaeetus albicilla), common ravens (Corvus corax) and black storks (Ciconia nigra). Among the eagle-owls of the fairly heavily wooded wildlands of Belarus, they more commonly utilize nests built by other birds than most eagle-owls, i.e. stork or accipitrid nests, but a majority of nests are still located on the ground.[71] This is contrary to the indication that ground nests are selected only if rocky areas or other bird nests are unavailable, as many will utilize ground nests even where large bird nests seem to be accessible.[14][71] Tree holes being used for nesting sites are even more rarely recorded than nests constructed by other birds. While it may be assumed that the eagle-owl is too large to utilize tree hollows, when other large species like the great grey owl have never been recorded nesting in one, the even more robust Blakiston's fish owl nests exclusively in cavernous hollows.[4][6] The Eurasian eagle-owl often uses the same nest site year after year.[24]
Eagle-owl has been singled out historically as a threat to game species and thus to the economic well-being of landowners, game-keepers and even governmental agencies and as such has been singled out for widespread persecution.[95][96] Local extinctions of Eurasian eagle-owls have been primarily due to persecution. Examples of this including northern Germany in 1830, the Netherlands sometimes in the late nineteenth century, Luxembourg in 1903, Belgium in 1943 and central and western Germany in the 1960s.[97] In trying to determine causes of death for 1476 eagle-owls from Spain, most were unknown and undetermined types of trauma. The largest group that could be determined, 411 birds, was due to collisions, more than half of which were from electrocution, while 313 were due to persecution and merely 85 were directly attributable to natural causes. Clearly, while pylon safety is perhaps the most serious factor to be addressed in Spain, persecution continues to be a massive problem for Spanish eagle-owls. Of seven European nations where modern Eurasian eagle-owl mortality is well-studied, continual persecution is by far the largest problem in Spain, although also continues to be serious (often comprising at least half of studied mortality) in France. From France and Spain, nearly equal numbers of eagle-owls are poisoned (for which raptors might not be the main target), or shot intentionally.[98][99]
Over 185 species of birds, more than half of the species that can be found in Romania, visit the park. Out of these, over 122 species nest here. Rare birds, such as the golden eagle, (also represented on the park logo), lesser spotted eagle, short-toed eagle, peregrine falcon, western capercaillie, Eurasian eagle-owl, Eurasian pygmy-owl and the black stork reside here.
Owls, which may have dissimilar periods of activity, are not entirely exempt from golden eagle predation either. Several species have been recorded as prey, especially in Northern Europe, Slovakia (where owls make up 2.4% of prey remains) and some parts of the Western United States. Species hunted have ranged in size from tiny Eurasian pygmy owl ("Glaucidium passerinum") and little owl ("Athene noctua") to the formidable, large great horned, Eurasian eagle and great gray owls ("Strix nebulosa"). Barn owls ("Tyto alba") have been predated by golden eagles in both North America and Eurasia. On Santa Rosa and Santa Cruz Islands, barn owls made up 4.5% of the diet, the largest known occurrence of that species in the eagles' diet. However, the great horned owl is the owl species that occurs most regularly in the diet of North American golden eagles. In Europe, golden eagles are relatively minor predators of owls compared to Eurasian eagle-owls and northern goshawks. The primary owls hunted by European eagles are Ural owls ("Strix uralensis") and short-eared owls ("Asio flammeus"). Few eye-witness accounts are known of owl predation, but one violent mid-day confrontation between a golden eagle and an adult great horned owl was witnessed in Jefferson County, Colorado. Although this owl was about a third of the eagle's weight, it was able to land some damaging blows on the larger bird. In the end, despite its wounds, the eagle was victorious over the dead owl. A case of kleptoparasitism by a golden eagle on a great horned owl has been recorded. Although the Eurasian eagle-owl is preyed upon by golden eagles (4 confirmed cases of golden eagles killing eagle-owls in Europe), in one case a golden eagle (age unspecified) was found amongst the prey in an eagle-owl nest.
The Eurasian eagle-owl is a very large bird, smaller than the golden eagle (Aquila chrysaetos) but larger than the snowy owl, despite some overlap in size with both species. It is sometimes referred to as the world's largest owl,[4][11] although Blakiston's fish owl (B. blakistoni) is slightly heavier on average and the much lighter weight great grey owl (Strix nebulosa) is slightly longer on average.[6][12][13] Heimo Mikkola reported the largest specimens of eagle-owl as having the same upper body mass, 4.6kg (10lb), as the largest Blakiston’s fish owl and attained a length of around 3cm (1.2in) longer.[4][14] In terms of average weight and wing size, the Blakiston’s is the slightly larger species seemingly, even averaging a bit larger in these aspects than the biggest eagle-owl races from Russia.[6][13] Also, although 9cm (3.5in) shorter than the largest of the latter species, the Eurasian eagle-owl can weigh well more than twice as much as the largest great grey owl.[4][15] The Eurasian eagle-owl typically has a wingspan of 131–188cm (4ft 4in–6ft 2in),[4] with the largest specimens possibly attaining 200cm (6ft 7in).[16][17][18][19] The total length of the species can vary from 56 to 75cm (22 to 30in).[4][6][20] Females can weigh from 1.75 to 4.6kg (3.9 to 10.1lb) and males can weigh from 1.22 to 3.2kg (2.7 to 7.1lb).[4][21] In comparison, the barn owl (Tyto alba), the world's most widely distributed owl species, weighs about 500g (1.1lb) and the great horned owl (Bubo virginianus), which fills the eagle-owl's ecological niche in North America, weighs around 1.4kg (3.1lb).[22]
Discreet habitat preferences may coincidentally spare many owls, as owls from the genera Strix, Glaucidium, Aegolius and the 320g (11oz) northern hawk-owl (Surnia ulula) tend to restrict both nesting and their hunting forays to more enclosed areas of woodland than habitats inhabited by the eagle-owls.[112][132] Meanwhile, Asio, Otus, Athene and barn owls owls tend to hunt in more open habitats than the edges favored by eagle-owls.[2] However, habitat preferences are never enough to spare any of these genera from predation by the great eagle-owl. In the Italian Alps, despite differing habitat preferences and partially overlapping prey, several tawny owls were killed by eagle-owls.[133] Woodland nesting owl species tend to nest in tree hollows, many of which are too small for an eagle-owl to access, so are somewhat less likely to be picked off at their nests. Open-country owls that tend to nest in open-access nesting sites like short-eared owls and little owls may be somewhat more vulnerable at the nest. The great numbers of long-eared owls taken, since it often nest in dense, protective thickets, are probably adult or immature owls attempting to hunt. In Europe, Eurasian eagle-owls are generally the only owls to regularly nest in rocky habitats. This is not the case in arid desert-like regions, where limited nesting options frequently force diverse owls to use rocky areas as nesting sites.[3][112] However, the cliffs and other rocky areas preferred by Eurasian eagle-owls are also utilized by several species of diurnal raptor in Eurasia. In Spain, golden eagles, Bonelli's eagles and peregrine falcons (Falco peregrinus) most often nest on cliffs. Large scavenging birds such as cinereous vultures (Aegypius monachus), bearded vultures (Gypaetus barbatus), Eurasian griffons (Gyps fulvus), Egyptian vulture (Neophron percnopterus) and common ravens also often nests on the same Iberian cliffs. While the two eagles nested at great distances from one another (they are known to be territorial towards each other), the eagle-owl nesting within 2 to 3km (1.2 to 1.9mi) of the other species. In these cliff nests, the only considerable predatory interaction was the eagle-owls appearing to predate the peregrine falcons.[134] In the Tibetan Plateau, upland buzzards (Buteo hemilasius) also seem to favor similar habitats and both the eagle-owl and buzzard take similar prey there.[50] In general, the eagle-owl can nest closer to diurnal raptors because, as a nocturnal animal, it will not actively compete for territories as it would with other members of its own species.[2]
In the lower Himalayas of northern Pakistan and Jammu and Kashmir, along with the brown fish owl, the Eurasian eagle-owl at the limit of its distribution may co-exist with at least two to three other eagle-owls.[6] One of these, the dusky eagle-owl (B. coromandus) is smaller, with more uniform tan-brownish plumage, untidy uniform light streaking rather than the Eurasian’s dark streaking below and an even less well-defined facial disc. The dusky is usually found in slightly more enclosed woodland areas than Eurasian eagle-owls.[4][14] Another is possibly the spot-bellied eagle-owl (Bubo nipalensis), which is strikingly different looking, with stark brown plumage, rather than the warm hues typical of the Eurasian, bold spotting on a whitish background on the belly, and somewhat askew ear tufts that are bold white with light brown crossbars on the front. It is possible that both species occur in some parts of the Himalayan foothills but they are not currently verified to occur in the same area, in part because of the spot-bellied’s preference for dense, primary forest.[14] Most similar, with basically the same habitat preferences and the only one verified to co-occur with the Eurasian eagle-owls of the race B. b. turcomanus in Kashmir is the Indian eagle-owl (B. bengalensis).[4] The Indian species is smaller with a bolder blackish facial disc border, more rounded and relatively smaller wings and partially unfeathered toes. Far to the west, the pharaoh eagle-owl (B. ascalaphus) also seemingly overlaps in range with the Eurasian, in at least the country of Jordan. Although also relatively similar to the Eurasian eagle-owl, the pharaoh is distinguished by its smaller size, paler, more washed-out plumage and the diminished size of its ear-tufts.[4][14]
Even those near the northern limits of their range, where winters are harsh and likely to bear little in food, the eagle-owl does not leave its native range. There are cases from Russia of Eurasian eagle-owls moving south for the winter, as the icebound, infamously harsh climate there is too severe even for these hardy birds and their prey. Similarly, Eurasian eagle-owls living in the Tibetan highlands and Himalayas may in some cases vacate their normal territories when winter hits and move south. Even in those two examples, there is no evidence of consistent, annual migration by Eurasian eagle-owls and the birds may eke out a living on their normal territories even in the sparsest times.[5][6]
The Eurasian eagle-owl (Bubo bubo) is a species of eagle-owl that resides in much of Eurasia. It is also called the European eagle-owl and in Europe, it is occasionally abbreviated to just eagle-owl.[3] It is one of the largest species of owl, and females can grow to a total length of 75cm (30in), with a wingspan of 188cm (6ft 2in), males being slightly smaller.[4] This bird has distinctive ear tufts, with upper parts that are mottled with darker blackish colouring and tawny. The wings and tail are barred. The underparts are a variably hued buff, streaked with darker colour. The facial disc is poorly developed and the orange eyes are distinctive.
While owls are apparently often killed by Eurasian eagle-owls while actively hunting, diurnal raptors are often ambushed at night at their large, conspicuous nests since they are easily located during hunting forays and the raptors are nearly defenseless in nocturnal conditions. The eagle-owl has been specified as the primary predator of common buzzards, peregrine falcons, common kestrel (Falco tinnunculus) and black kites.[131][135][136][137] The common buzzard and 184g (6.5oz)common kestrel are probably the most often selected diurnal raptors because they inhabit the edges most often hunted by the eagle-owls. Studies have shown that 743g (1.638lb) peregrine falcon experience lower productivity in areas where they nest closely to eagle-owls, as the eagle-owls pick off both nestlings and adults by night. However, peregrine populations were not hugely effected except in cases where small reintroductions were attempted of falcons or falcon populations were already rare due to other causes.[95][135] The northern goshawk is itself a serious predator of other raptors. The eagle-owl is the goshawk's only major predator, although goshawks are not as intensely hunted as are buzzards due to their more deeply wooded preferred nesting habitat.[138]
Despite the alternate common name of giant eagle-owl, the Verreaux's eagle-owl is not the largest owl or eagle-owl in the world. It is, however, a very large and powerful owl species. This species is both the largest owl found in Africa and the world's largest owl to occur in the tropics. Among all the world's owls, it is fourth heaviest living owl, after Blakiston's fish owl ("Bubo blakistoni"), the Eurasian eagle-owl ("Bubo bubo") and the tawny fish owl ("Bubo flavipes"), and is also the fourth longest living owl (measured from the bill to the tip of the tail), after the great gray ("Strix nebulosa"), Blakiston's fish and Eurasian eagle-owls. Based on body mass and wing chord length, Verreaux's eagle-owl is about the same size as "medium-sized" races of Eurasian eagle-owl, such as those from Central Asian steppe ("B. b. turcomanus") and the Himalayas ("B. b. hemachalana"), slightly smaller than most northern Eurasian races, considerably smaller than Siberian and Russian eagle-owls, and somewhat larger than the smallest Eurasian eagle-owl subspecies, such as those from the Iberian Peninsula ("B. b. hispanus") and the Middle East ("B. b. omissus" or "nikolskii").
The fourth and most famous derivation of the evolutionary line that includes the Eurasian eagle-owl is the great horned owl, which appears to have been the result of primitive eagle-owls spreading into North America.[6] It has been stated that the great horned owls and Eurasian eagle-owls are barely distinct as species, with a similar level of divergence in their plumages as the Eurasian and North American representations of the great grey owl or the long-eared owl.[6] There are more outward physical differences between the great horned owl and the Eurasian eagle-owl than in those two examples, including a great size difference favoring the Eurasian species, the great horned owl’s horizontal rather than vertical underside barring, yellow rather than orange eyes and a much strong black bracket to the facial disc, not to mention a number of differences in their reproductive behaviour and distinctive voices.[14] Furthermore, genetic research has revealed that the snowy owl is more closely related to the great horned owl than are Eurasian eagle-owls.[14] The most closely related species beyond the Pharaoh, Indian and Cape eagle-owls to the Eurasian eagle-owl is the smaller, less powerful and African spotted eagle-owl (B. africanus), which was likely to have divided from the line before they radiated away from Africa. Somehow, genetic materials indicate the spotted eagle-owl appears to share a more recent ancestor with the Indian eagle-owl than with the Eurasian eagle-owl or even the sympatric Cape eagle-owl.[14] Eurasian eagle-owls in captivity have produced apparently healthy hybrids with both the Indian eagle-owl and the great horned owl.[4][6] The Pharaoh, Indian and Cape eagle-owls and the great horned owl are all broadly similar in size to each other, but all are considerably smaller than the Eurasian eagle-owl, which averages at least 15–30% larger in linear dimensions and 30–50% larger in body mass than these other related species, possibly as the eagle-owls adapted to warmer climates and smaller prey. Fossils from south France have indicated that during the Middle Pleistocene, Eurasian eagle-owls (this paleosubspecies given the name B. b. davidi) were larger than they are today, even larger were those found in Azerbaijan and in Caucasus (either B. b. bignadensis or B. bignadensis), which were deemed to date to the Late Pleistocene.[6] About a dozen subspecies are recognized today.[2]
Although other birds of prey are seldom caught, given that they are wary, fast and can defend themselves well, the white-tailed eagle can be characterized as an opportunistic predator of such birds. Indicating that they are regarded as a threat to raptors is that they are frequently mobbed by a wide range of raptor species when displaying active flights, to a similar regard that the perhaps more aggressively predatory golden eagle is. Given the difficulty of this prey type, white-tailed eagles are likely to attack other birds of prey when the victims are distracted, whether by migration on windy days, nesting duties or when trying to capture their own prey, are previously injured or they may even capture one while the raptor tries to mob the eagle. Certainly, nestlings and fledglings can certainly comprise a large fraction of the birds of prey caught as well as adult ones. Other accipitrids they are known to have preyed upon, in increasing order of size are the Eurasian sparrowhawk ("Accipiter nisus"), western marsh harrier ("Circus aeruginosus"), black kite ("Milvus migrans"), European honey-buzzard ("Pernis apivorus"), common buzzard ("Buteo buteo"), northern goshawk, red kite ("Milvus milvus"), lesser spotted eagle ("Clanga pomarina") and eastern imperial eagle, in addition to osprey. Non-accipitrid raptorial birds, these more likely restricted to fully independent birds due to their less conspicuous nests, known to fall prey to white-tailed eagles include Eurasian pygmy owl ("Glaucidium passerinum"), boreal owl ("Aegolius funereus"), Eurasian hobby ("Falco subbuteo"), long-eared owl (Asio otus), northern hawk owl ("Surnia ulula"), short-eared owl ("Asio flammeus"), peregrine falcon ("Falco peregrinus"), snowy owl ("Bubo scandiacus") and Eurasian eagle owl ("Bubo bubo"). Accipitrid prey size ranges by body mass ranges from for a sparrowhawk to in the imperial eagle and that of non-accipitrid raptors ranges from for the pygmy owl to for the eagle owl and apparently both imperial eagles and eagle owls that were caught were adults. As true apex predators, healthy adult white-tailed eagles have no known natural predators.
The Eurasian eagle-owl rarely assumes the so-called "tall-thin position", which is when an owl adopts an upright stance with plumage closely compressed and may stand tightly beside a tree trunk. Among others, the long-eared owl is among the most often reported to sit with this pose.[24] The great horned owl has been more regularly recorded using the tall-thin, if not as consistently as some Strix and Asio owls, and it is commonly thought to aid camouflage if encountering a threatening or novel animal or sound.[6] The Eurasian eagle-owl is a broad-winged species and engages in a strong, direct flight, usually consisting of shallow wing beats and long, surprisingly fast glides. It has, unusually for an owl, also been known to soar on updrafts on rare occasions. The latter method of flight has led them to be mistaken for Buteos, which are smaller and quite differently proportioned.[67] Usually when seen flying during the day, it is due to being disturbed by humans or mobbing crows.[14] Eurasian eagle-owls are highly sedentary, normally maintaining a single territory throughout their adult lives.
Other than these two species, a large share of the raptorial prey for eagle-owls is made up of other owls. Given that all European owls are to some extent nocturnal, they may be encountered and killed upon detection by the Eurasian eagle-owl. In Europe, it has killed every other species of owl, from the tiny pygmy owl and scops owl to the large 1,078g (2.377lb) great grey owl and the 2,040g (4.50lb) snowy owl.[126] The Eurasian eagle-owl is the only raptor that has been known to prey on snowy owl on multiple occasions.[95][112][126] However, the threat Eurasian eagle-owls poses to other raptors can be exaggerated.[129] Occasionally, with adequate mammal prey populations, they can nest as close as a few dozen meters of other raptors and never harass them.[112] When nesting in the same groves as the 1,175g (2.590lb) long-legged buzzards (Buteo rufinus) in southeastern Bulgaria, Eurasian eagle-owls did not predate the buzzards at any point.[95][130] Long-legged buzzards have been killed however in Kazakhstan.[77] Even in those occasional cases where they pick off one or several raptors, they do not effect the overall population, unless the raptorial prey is already heavily diminished due to some other (often human-based) cause. For example, despite both being a known predator of both, they did not significantly depress numbers of either northern goshawks or tawny owls in southern Finland.[129] One study showed that many raptors engage in spatial avoidance during potential encounters with Eurasian eagle-owls and while the predation by eagle-owls did decrease raptor population densities, they seldom caused declines in breeding success or altered habitat occupancy.[131]
The great size, bulky, barrel-shaped build, erect ear tufts and orange eyes render this as a distinctive species. Other than general morphology, the above features differ markedly from those of two of the next largest subarctic owl species in Europe and western Asia, which are the great grey owl and the greyish to chocolate-brown Ural owl (Strix uralensis), both of which have no ear tufts and have a distinctly rounded head, rather than the blocky shape of the eagle-owl’s head.[4][14] The snowy owl is obviously distinctive from most eagle-owls, but during winter the palest Eurasian eagle-owl race (B. b. sibiricus) can appear off-white. Nevertheless, the latter is still distinctively an ear-tufted Eurasian eagle-owl and lacks the pure white background colour and variable black spotting of the slightly smaller species (which has relatively tiny, vestigial ear tufts that have only been observed to have flared on rare occasions).[5][14] The long-eared owl has a somewhat similar plumage to the eagle-owl but is considerably smaller (an average female eagle-owl may be twice as long and ten times heavier than an average long-eared owl).[28]
Conversely to numerous threats and declines incurred by Eurasian eagle-owls, areas where human-dependent non-native prey species such as brown rats (Rattus norvegicus) and rock pigeons (Columba livia) have flourished, have given the eagle-owls a primary food source and allowed them occupy regions where they were once marginalized or absent.[60]
The Eurasian eagle-owl at one time occurred naturally in Great Britain. Some, including the RSPB have claimed that this was probably by about 10,000–9,000 years ago after the last ice age but fossil remains found in Meare Lake Village have indicated the eagle-owl occurring as recently as roughly 2,000 years ago in the fossil record.[104][105] The lack of presence of the Eurasian eagle-owl in British folklore or writings in recent millennium may indicate the lack of occurrence by this species there.[103] The flooding of the land bridge between Britain and continental Europe may have been responsible for their extirpation as they only disperse over limited distances, although early human persecution presumably played a role as well. Some reportages of eagle-owls in Britain have been revealed to actually be great horned owls or Indian eagle-owls, the latter a particularly popular owl in falconry circuits.[103] Some breeding pairs do still occur in Britain, the exact number of pairs and individuals is not definitely known. The World Owl Trust stated that they believe some eagle-owls occurring in North England and Scotland are naturally occurring, making the flight of roughly 350 to 400km (220 to 250mi) from the west coast of Norway to Shetland and the east coast of Scotland, as well as possibly from the coasts of the Netherlands and Belgium to the south. Although not migratory, eagle-owls can disperse some notable distances in young birds seeking a territory.[104] Prior studies of eagle-owl distribution have indicated a strong reluctance to cross large bodies of water in the species. Many authorities state that the Eurasian eagle-owls occurring in Britain are individuals that have escaped from captivity.[103][106] While, until 19th century, wealthy collectors may have released unwanted eagle-owls, despite press to the contrary, there is no evidence of any organization or individual intentionally releasing eagle-owls recently with the intent to establish a breeding population.[103] Many feel that the eagle-owl would be classified as an "alien" species. Due to its predatory abilities, many, especially those in the press, have expressed alarm of their effect on "native" species.[107] From 1994 to 2007, 73 escaped eagle-owls were not registered as returned, while 50 escapees were re-captured.[103] Several recorded breeding attempts have been studied and most were unsuccessful, due in large part to incidental disturbance by humans and some due to direct persecution, with eggs having been smashed.[103]
Eurasian eagle-owls are strictly territorial and will defend their territories from interloping eagle-owls year around, but territorial calling appears to peak around October to early January.[66] Territory size is similar or occasionally slightly greater than great horned owl: averaging 15 to 80km2 (5.8 to 30.9sqmi).[6] Territories are established by the male eagle-owl, who selected the highest points in the territory from which to sing. The high prominence of singing perches allows their song to be heard at greater distances and lessens the need for potentially dangerous physical confrontations in the areas where territories may meet.[66] Nearly as important in territorial behaviour as vocalization is the white throat patch. When taxidermied specimens with flared white throats were placed around the perimeter of eagle-owl territories, male eagle-owls reacted quite strongly and often attacked the stuffed owl, reacting more mildly to a stuffed eagle-owl with a non-flared white throat. Females were less likely to be aggressive to mounted specimens and did not seem to vary in their response whether exposed to the specimens with or without the puffed up white patch.[68] In January and February, the primary function for vocalization becomes for the purpose of courtship.[66] More often than not, eagle-owls will pair for life but usually engage in courtship rituals annually, most likely to re-affirm pair bonds.[14] When calling for the purposes of courtship, males tend to bow and hoot loudly but do so in a less contorted manner than the male great horned owl.[6] Courtship in the Eurasian eagle-owl may involve bouts of "duetting", with the male sitting upright and the female bowing as she calls. There may be mutual bowing, billing and fondling before the female flies to a perch where coitus occurs, usually taking place several times over the course of a few minutes.[24]
In rare cases, other predators may kill a Eurasian eagle-owl. In Europe, there is one case of a white-tailed eagle killing an eagle-owl and there are at least four known incidents of eagle-owls being killed by golden eagles.[126] Also, an eagle-owl was found among the prey remains at a golden eagle eyrie in Mongolia.[146] An eagle-owl was also found amongst the prey in the nest of steppe eagles (Aquila nipalensis) in Altai Krai, Russia.[147] In 2016, a large female subadult Bonelli's eagle (Aquila fasciata) apparently preyed upon a three-year-old male Eurasian eagle-owl in Spain.[148] Pine martens (Martes martes) and stone martens (Martes foina) are opportunistic nest predators. Although martens could probably reach most eagle-owl nests due to their agility and climbing abilities, they probably will attack nests when disturbance or low food supply result in lower nest attendance by the parent owls. Cases where nests have atypically been accessible on foot (for both humans and wild predators) have resulted in Eurasian eagle-owl nests being predated. Eurasian badgers, wild boars and raccoon dogs and raccoons, the latter two both where non-native in Germany, have also reportedly preyed on nests that they can access. In coastal areas of Spain, red foxes were reported to have preyed on four eagle-owls, including one unsexed brooding adult, at nests found to be reachable on foot by researchers. Cases of red foxes killing Eurasian eagle-owls at nests have reported elsewhere albeit very rarely, normally the eagle-owl is a greater danger to the foxes (and many of its other nest predators) than vice versa.[149][150] In May 2017, a red fox was filmed killing two chicks and raiding the larder of an eagle-owl in Denmark.[151]
Equally or even more so than the great horned owl, the Eurasian eagle-owl is a threat to any smaller type of raptor it encounters, whether other owls or diurnal birds of prey. All told, more than 20 species of accipitrid, 15 species of owl and 9 species of falcon have been found amongst their prey. The Eurasian eagle-owl is the primary predator of other birds of prey throughout Eurasia, not even the prolific raptor-killing northern goshawk (Accipiter gentilis) equals the sheer number of raptors taken.[79][126][127] Up to 6% of the overall food by number and 36% by prey biomass for Eurasian eagle-owls can be comprised by other raptorial birds.[2][79] The primary raptorial prey taken by Eurasian eagle-owls in Europe are two species: the 300g (11oz) long-eared owl and the 776g (1.711lb) common buzzard.[2][95] Both are taken in such large numbers that they rank in the top five most regularly hunted bird species in Europe. In Luxembourg, the long-eared owl and common buzzard were the fourth and fifth most regularly hunted prey species.[96] Other high rankings have included the long-eared owl being the fourth most regular prey species in Bavaria and the buzzard being the third most regular prey species in a study from the Czech Republic.[75][128] While migrating, long-eared owls appear to select areas to move through partially based on whether or not eagle-owls are detected, thus eagle-owls have a very serious influence on the behaviour of this prey.[15] Despite the large numbers taken of both of these, the more scarce eagle-owl does not seem to have a serious deleterious effect on their overall population, especially compared to anthropogenic factors.[2][126]
Apparently, the point at which the chicks venture out of the nest is driven by the location of the nest. In elevated nest sites, chicks usually wander out of the nest at 5 to as late as 7 weeks of age, but have been recorded leaving the nest if the nest is on the ground as early as 22 to 25 days old.[14] The chicks can walk well at five weeks of age and by seven weeks are taking short flights. Hunting and flying skills are not tested prior to the young eagle-owls leaving the nest. Young Eurasian eagle-owls leave the nest by 5–6 weeks of age and typically can be flying weakly (a few metres) by about 7–8 weeks of age. Normally, they are cared for at least another month. By the end of the month, the young eagle-owls are quite assured fliers.[6] There are a few confirmed cases of adult eagle-owls in Spain feeding and caring for post-fledgling juvenile eagle-owls that were not their own.[81]
Long-eared owls in Eurasia have vertical striping like that of the Eurasian eagle-owl while long-eared owls in North America show a more horizontal striping like that of great horned owls. Whether these are examples of mimicry either way is unclear but it is known that both Bubo owls are serious predators of long-eared owls. The same discrepancy in underside streaking has also been noted in the Eurasian and American representations of the grey owl.[6] A few other related species overlap minimally in range in Asia, mainly in east Asia and the southern reaches of the Eurasian eagle-owl’s range. Three fish owls appear to overlap in range, the brown (Ketupa zeylonensis) in at least northern Pakistan, probably Kashmir and discontinuously in southern Turkey, the tawny (K. flavipes) through much of eastern China and the Blakiston's fish owl in the Russian Far East, northeastern China and Hokkaido. Fish owls are distinctively different looking, possessing more scraggy ear tufts that hang to the side rather than sit erect on top of the head, generally have more uniform, brownish plumages without the contrasting darker streaking of an eagle-owl. The brown fish owl has no feathering on the tarsus or feet and the tawny has feathering only on the upper portion of the tarsi but the Blakiston’s is nearly as extensively feathered on the tarsi and feet as the eagle-owl. Tawny and brown fish owls are both slightly smaller than co-occurring Eurasian eagle-owls and Blakiston’s fish owls are similar or slightly larger than co-occurring large northern eagle-owls. Fish owls, being tied to the edges of freshwater where they hunt mainly fish and crabs, also have slightly differing, and more narrow, habitat preferences.[4][14]
Snowy owls are not known to interbreed with other owl species in the wild, and accordingly no hybrids of snowy owls and other owl species have yet been sighted in the wild. However, a hobby falconer in Kollnburg, Germany, managed to successfully breed hybrids from a male snowy owl and a female Eurasian eagle-owl in 2013. The two resulting male hybrid owls possessed the prominent ear tufts (generally absent in snowy owls), general size, orange eyes, and the same pattern of black markings on their plumage from their Eurasian eagle-owl mother, while retaining the generally black-and-white plumage colours from their snowy owl father. The hybrids were dubbed ""Schnuhus"", a portmanteau of the German words for snowy owl and Eurasian eagle-owl ("Schnee-Eule" and "Uhu", respectively). As of 2014, the hybrids had grown to maturity and were healthy.