Seeadler

Bestimmung

The white-tailed eagle is one of the largest living birds of prey. It is the largest of the dozen species of eagle found in Europe and the largest eagle across its distribution, excluding the Russian Far East and (during the winter) Hokkaido, Japan, where it co-exists with its larger cousin, Steller's sea eagle. The white-tailed eagle is sometimes considered the fourth largest eagle in the world and is, on average, the fourth heaviest eagle in the world. The only extant eagle species known to be more massive in mean bulk are the Steller's sea eagle (Haliaeetus pelagicus), the harpy eagle (Harpia harpyja) and the Philippine eagle (Pithecophaga jefferyi). The white-tailed eagle measures anywhere from 66 to 94 cm (26 to 37 in) in total length with a typical wingspan of 1.78 to 2.45 m (5 ft 10 in to 8 ft 0 in). This species may have the largest wingspan of any living eagle. The Steller's sea eagle, which is larger in weight, total length and non-wing standard measurements, may be the closest rival for median wingspan amongst living eagles. The white-tailed eagle does appear to outsize the average wingspan of the wedge-tailed eagle (Aquila audax), which is sometimes also titled the largest winged extant eagle due to an exceptionally large individual shot in 1931, although the Steller's sea eagle may rival it in that respect. <p>In one sample from Norway, five male white-tailed eagles were found to average 2.26 m (7 ft 5 in) and eight females were found to average 2.37 m (7 ft 9 in). In another sample of wild birds of unspecified origin, five males were found to average 2.1 m (6 ft 11 in) and seven females averaged 2.3 m (7 ft 7 in). Record wingspans have included a specimen from Greenland which measured 2.53 m (8 ft 4 in) while another specimen apparently spanned 2.6 m (8 ft 6 in). The bald eagle broadly overlaps in size with the white-tailed eagle. In direct comparison, the white-tailed eagle averages somewhat larger in body mass than the bald eagle and may be marginally larger in bill and talon size, although these linear aspects can be quite similar between the two species. The white-tailed eagle does have a significantly larger wing chord and average wingspan than the bald eagle, but the latter usually possesses a longer tail, resulting in a larger total length than the white-tailed eagle and a larger mean tarsal length.<p>Size variation is generally a clinal trend and is normally quantified using standard measurements such as wing, tail and tarsal length, or body mass, rather than wingspan or total length. As expected for many widely distributed animals of varied lineages, the white-tailed eagle conforms to Bergmann's rule in that more northerly birds tend to outsize those found relatively closer to the Equator. Average size also decreases from west to east across its distribution. The largest white-tailed eagles appear to be found in Greenland, these being slightly larger than those from Ireland, Scotland and Scandinavia and notably larger than eagles from central Europe, especially in proportions of the wing area. Those from the southerly portions of the breeding range, such as Asia Minor (principally Turkey), southern Kazakhstan, and Korea Bay, appear to be the smallest-bodied population but there have been limited measurements and published weights known for these extremely sporadic and rare Asian populations of eagle. Furthermore, weights of fully grown eagles from Greenland are not known. Unlike many accipitrids, juvenile white-tailed eagles (and seemingly other sea eagles as well) are often of similar weight to the adults, although the juveniles typically have a somewhat larger average wing and tail length than the adults. In the white-tailed eagle, body mass can typically range from 4 to 6.9 kg (8.8 to 15.2 lb) in females. The slightly smaller male may typically weigh from 3.1 to 5.4 kg (6.8 to 11.9 lb). <p>Average weights in European white-tailed eagles can range from 4.02 kg (8.9 lb) in five males and 5.11 kg (11.3 lb) in nine females to (from the reintroduced birds of Scotland of Norwegian stock) 4.98 kg (11.0 lb) in 39 males and 6.06 kg (13.4 lb) in 43 females. In comparison, the weight ranges for white-tailed eagles from Northeast China were claimed to be only 2.8 to 3.78 kg (6.2 to 8.3 lb) in males and 3.75 to 4.6 kg (8.3 to 10.1 lb) in females. The heaviest female white-tailed eagles can apparently weigh as much as 7.5 to 8 kg (17 to 18 lb) and even males can sometimes weigh up to 6.5 kg (14 lb), which would make the largest males perhaps the heaviest recorded modern male eagle, as male harpy and Philippine eagles (being more sexually dimorphic in favour of the female) are not known to exceed 5 kg (11 lb) (the highest weights for male Steller's sea eagle are not known). The global mean body mass of white-tailed eagles is estimated at approximately 5 kg (11 lb). The average female Steller's sea eagle may weigh just under 25% more than the average female white-tailed eagle (the average weight of male Steller's is not known) while the average European golden eagle may weigh about 11–12% less than the average European white-tailed eagle and the bald eagle species as a whole about 10% less than the white-tailed eagle species.<p>The most reliable method to sex birds is by tarsus width and depth and bill depth but these are infrequently measured. In some cases females are as much as 25% heavier and 15% greater in linear dimensions, though the sexes are rarely this discrepant in standard measurements. Among standard measurements, the wing chord is 552 to 695 mm (21.7 to 27.4 in) in males, averaging 606 and 645 mm (23.9 and 25.4 in) in European adults and juveniles, respectively, and 646.5 mm (25.45 in) in Greenland males. In females, the wing chord may measure 605 to 740 mm (23.8 to 29.1 in), averaging 668 and 685 mm (26.3 and 27.0 in) in European adults and juveniles, respectively, and 691.3 mm (27.22 in) in Greenland females. Adult tail length is 250 to 331 mm (9.8 to 13.0 in) in males, averaging 280 mm (11 in), and 276 to 330 mm (10.9 to 13.0 in) in females, averaging 305 mm (12.0 in). Juvenile tail lengths can reach roughly 380 mm (15 in) in both sexes, however. The tarsus is 90 to 101 mm (3.5 to 4.0 in), averaging 95.5 mm (3.76 in). <p>In terms of their killing apparatuses, their hallux claw, the largest talon on all accipitrids, is 37 to 46 mm (1.5 to 1.8 in) in length, averaging 40.9 mm (1.61 in). The hallux claw averages about a centimeter less than that of a golden eagle and is more sharply curved, an adaptation to prevent escape of slippery prey such as fish, while that of a bald eagle is similarly about 40.4 mm (1.59 in) and of similar curvature. The exposed culmen is typically large as in all Haliaeetus, ranging from 45 to 65 mm (1.8 to 2.6 in), with an average of 56.1 mm (2.21 in). The average culmen length of the bald eagle is 54.3 mm (2.14 in), thus averaging slightly smaller. However, the average culmen length in the large bald eagles of Alaska is considerably larger than other bald eagles as well as most white-tailed eagles at up to 75 mm (3.0 in) and can even rival the length (but perhaps not the girth) of the truly massive bill of the Steller's sea eagle.<p>The adult white-tailed eagle is a greyish mid-brown colour overall. The plumage is fairly uniform over most of the body and wings, but the upper wing coverts are typically somewhat paler. In the adult, the head, neck and upper breast have a distinctly paler appearance than the rest of the plumage and most often have a buff coloration. In worn or bleached plumages these light areas can be even paler at times, ranging to almost whitish, which can render a resemblance in such eagles to a washed-out bald eagle. Some of the palest birds can appear anywhere from cream-tawny to light greyish. It is thought that in some populations perhaps paleness increases with age, although it is possible that there is an historical genetic factor to these pale variations. In contrast, some adults can also be a richer, more deeply dark brown (or somewhat rufescent) than average with perhaps a mild increase in average darkness of hue to the east of the species' range. When many of the feathers are freshly moulted, they can take on a slight purplish gloss. The brownish hue of the adult overall makes the somewhat wedge-shaped white tail stand out in contrast. All the bare parts of the adult's body are yellow in colour, including the bill, cere, feet and eyes. Juvenile and immature white-tailed eagles are a much darker brown than the adults and are more unevenly marked, with whitish feather edgings variably showing, mostly manifesting in some small areas of the underside and under-wing, with a narrow white axillary strip usually apparent.<p>The upperside is usually similarly darkish brown but variable based on extent of blackish-brown tip to otherwise buff-brown feathers of the mantle, back and upper wing. The head of the juvenile is normally a blackish-brown hue, somewhat darker and always more uniform than most of the other feathers. The juvenile's tail tends to be a washed out greyish-cream colour with messy blackish colour on the feather edges and on the tips. Some individual juveniles may exhibit some faint barring on the tail while others may appear largely dirty whitish on the tail. The bill of juveniles is usually almost half dark brown from the tip and half dirty, dull yellowish or grey to the base, while the feet are usually a dirty yellow and the eyes are a darkish brown. Juvenile males may average a slightly darker brown plumage with less speckling on the upper body than like-age females; their head and neck plumes may also appear shorter, which can accentuate the slighter, more angular skull possessed by males. In disposition, the male juveniles are said to be more highly strung and higher voiced than their female counterparts. <p>The head gradually grows paler over several years. The whitish mottling may increase on the upperparts, belly and especially on the underwing area later into their third year (considered the first subadult plumage) and subadult birds can appear fairly blotched with white but much individual variation in colouring is known at this age. However, this white mottling then fades late into the fourth year and the plumage becomes less contrasting. Although sexual maturity is considered to be attained at between five and six years of age, usually the fully white tail and the uniform pale head and neck are not obtained until the eighth year. Juveniles first moult in May/June until October/November at just over one year of age. Their second moult is the following year in March or April, with two more subsequent moults usually beginning around this time for the next couple of years. Like other large raptors, feathers are moulted at slow intervals so as not to inhibit food capture. Only relatively small proportions of the flight feathers are moulted each year. Moulting occurs more or less continuously, although it may pause in winter if food is in short supply.<p>White-tailed eagles of all ages typically perch in quite upright positions on exposed branch, rock or other vantage point, but tend to sit more horizontally on the ground or other level surfaces. They have an ample bill with a relatively high culmen, helping to impart a rather narrow and high crowned facial look, especially compared to Aquila eagles. The neck is at times unusually long-looking, more so than in the bald eagle, which can give the upper body a vulturine appearance. The tail is relatively short, and in some adults it can appear disproportionately stubby in relation to the massive body, and slightly wedge-shaped. All ages have a well-feathered tibia but bare tarsi. In flight, the wings are extremely broad and deeply fingered, with the usual tendency for at least six fingers to be visible. Juveniles are longer tailed than adults, which is usually more evident in flying than perched birds, with sometimes a slightly bulging section of feathers manifesting on the wing secondaries. The species tends to fly with shallow wing beats; at times the wing beats can be fairly fast for a bird of this size, but interspersed at times with gliding. At a great distance, this flight style may be suggestive of a large brown heron. The wings are held flat or slightly upraised at the tip in flight and the white-tailed eagle is well known to soar extensively. This species can be surprisingly maneuverable on the wing, usually during aerial displays or dogfights with other birds. These eagles may also maneuver by half-closing both wings or fully closing one wing.<p>The white-tailed eagle is considered a vocal bird of prey during the breeding season, although some authors consider their voice "not loud or impressive for the size of the bird". The male call is oft transcribed as gri-gri-gri or krick-krick-krick, while the female is a deeper gra-gra-gra-gra or krau-krau-krau-krau. These will increase in tempo and pitch, with about 15–30 calls in a sequence. Often pairs will duet during early spring, in flight or from a perch. When perched, the male calls kyi-kyi-kyi-kli-kliek-yak with the head thrown back and upwards in the last call ended with a lower ko-ko-ko, the perched call of females is similar but deeper, a krau-krau-krau-uik-ik. Typically, the perched version of their calls tend to be shriller and higher than those issued in flight. <p>In courtship display, male calls krau-krau-krau-uik-ik-ik answered by females with a lower ra-rack-rack-rack-rack. Young in nest call a shrilly piieh-piieh, while the female when receiving food from male calls out with tschie-tschie or vueee-vueee. Single or repeated krlee or similar component of calls used in other circumstances, can be variable. Alarm calls tend to be 3–4 short, loud klee or klek notes. Sometimes a different call of alarm or anger, a deep gah-gah-gah or jok-jok-jok, similar to alarm calls of a large gull, is also uttered when a nest is approached (usually recorded while directed towards humans). The young let out a monotonous veee-veee when hungry (or "bored") which intensifies if the eaglets are not fed or brooded immediately.<p>Given reasonable view, adult white-tailed eagles are difficult to mistake for any other bird. There are no other eagles with fully white tails in their range except for in the easternmost limits of their range, their cousins the bald eagle and Steller's sea eagle, which in adults are different in all other respects of plumage. Even in poor light, the bald species shows a sharp demarcation from white to dark brown whereas the colour contrast is far subtler in white-tailed eagles between their brown body (of a paler hue than that of a bald eagle) and buff-coloured head. At a great distance, the adult may be potentially confusable with the Griffon vulture (Gys fulvus), as the colouring of the two species is vaguely similar and they can overlap somewhat in size although the vulture can average rather heavier and longer winged. However even at long range, the relatively tiny head, distinctly curved trailing wing-edges and more raised wings make the vulture distinctive from the white-tailed eagle.<p>Juveniles may be harder to distinguish, mainly from other sea eagles in few areas of overlap. In northern Mongolia (perhaps spilling over into southern Siberia), the northern part of the Caspian Sea and some central and southern parts of Kazakhstan, the white-tailed eagle may (or may not) live alongside the rarer, relatively poorly-known Pallas's fish eagle. The Pallas's juveniles are more distinctively whitish marked on the underwing. In flight or perched, the Pallas's fish eagle are usually markedly smaller and slighter than white-tailed eagles with a longer and differently marked tail. At all ages, the white-tailed eagle averages a duller, slightly darker and browner colour overall than the Pallas's fish eagle. Pallas's fish eagles are mid-brown on the body in juvenile plumage with no paler feather edging as seen in juveniles and especially subadults of the larger species. Adult Pallas's fish eagles are immediately distinctive rufous hue with a more restricted but more sharply demarked paler buffy head. Bald eagle juveniles may be found together with white-tailed eagles in the Aleutian islands (where the white-tailed eagle formerly bred until about 30 years ago) and when vagrants of white-tails occur in Alaska. Juveniles of bald and white-tailed eagles often strongly resemble each other but the bald eagles have a shorter neck, a relatively longer and squarer tail, and somewhat less broad wings. In the colouring, the bald juvenile is similarly as dark or even darker brown above as white-tailed eagle juveniles but on the underside often has more extensive whitish mottling, especially on the underwing.<p>Steller's sea eagles are usually distinctly larger and longer tailed, with a taller, bulkier look in eagles standing on the ground or perched. Steller's juveniles have a different wing shape (roughly paddle-shaped) and a considerably more massive and paler bill, which is yellow even in juveniles unlike in bald and white-tailed eagles. Juvenile Steller's sea eagles are a distinctly darker soot colour than juvenile white-tailed eagles with even less whitish showing on the body than the latter species but, on the other hand, the underwing often as white marked as juvenile bald eagles (dissimilarly from juvenile white-tailed eagles), albeit in different pattern. In all three large northern sea eagles, the tail colour is similar at the various stages of development but the shape is more distinctive, especially the bolder wedge shape of the Steller's.<p>The cinereous vulture (Aegypius monachus) may too be considered superficially similar to the juvenile white-tailed eagle, but it is considerably larger and longer-winged and possesses a more uniform and darker hue with conspicuous paler legs and a relatively smaller head. Young white-tailed eagles are also potentially confusable with any Aquila, but should be obvious even as a silhouette in its huge wings, relatively truncated and slightly wedge-shaped tail and obvious projection of the neck and head. All Aquila lack pale the axillary band often visible on juvenile and subadult white-tailed eagles. Some greater spotted eagles (Clanga clanga) can suggest the wing shape of a white-tailed eagle but are far smaller and shorter winged and never bear a protruding head. Similarly, the eastern imperial eagle (Aquila heliaca) may suggest a white-tailed eagle in its flat wing profile and relatively large head and neck but is also visibly smaller with far less broad wings and a relatively longer tail. Like all Clanga and Aquila, both greater spotted and eastern imperial eagles should be obviously distinct from white-tailed eagles by plumage characteristics. The golden eagle usually appears slightly smaller than the white-tailed eagle and tends to be more dashing in flight, which is usually done with a distinct dihedral. When perched, the golden eagle looks more sleek and compact than the rangier white-tailed eagle and tends to be a darker, richer hue of brown. Golden eagles have a much shorter neck, with a smaller head and bill and a longer, squarer tail. White wing patches of juveniles are also differently distributed in golden than juvenile white-tailed eagles.

Taxonomie

The first formal description of the white-tailed eagle was by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Falco albicilla. The genus Haliaeetus was introduced in 1809 by the French naturalist Marie Jules César Savigny in the Description de l'Égypte. The name Haliaeetus is Neo-Latin for "sea-eagle", from Ancient Greek hali-, "sea-" and aetos, "eagle". The specific albicilla, "white-tailed", is from Neo-Latin albi-, "white" and cilla, "tail". The Anglo-Saxon name erne means "soarer", and it is cognate to Swedish örn and Finnish aarni. It has many Gaelic names, including iolar sùil na grèine or 'eagle of the sun's eye.' The white-tailed eagle is a member of the genus Haliaeetus, a monophylic group comprising 11 living species, including the closely related Ichthyophaga fish eagles which may or may not be part of a separate genus. The latter group, comprising the lesser (Haliaeetus humilis) and the grey-headed fish eagle (Haliaeetus ichthyaetus), differ mostly in life history, being more fully devoted to fish eating and habituating wooded areas, especially in mountainous areas. In appearance the two Ichthyaetus are slenderer, longer tailed and more uniform and grey in colour than typical sea eagles. This species pair may not be genetically distinct enough to warrant division into separate genera. Other than these Ichthyophaga-type species found farther north in Asia, Sanford's sea eagle (Haliaeetus sanfordi) of the Solomon Islands is the most atypical Haliaeetus, retaining rufous-brown plumage into adulthood (this particularly resembling the white-bellied sea eagle juvenile, likely a closely related species) more typical of juveniles in other species and it also dwells more so in dense, coastal forests where it feeds mostly on birds and mammals rather than fish and water birds. <p>Outside of the genus Haliaeetus, among other extant forms, they appear to be most closely related to milvine kites and Old World vultures, based on modern forms from these subfamilies that broadly share morphological and life history traits with sea eagles: the Brahminy kite (Haliastur indus) (historically sometimes referred to as the "red-backed sea eagle") and the palm-nut vulture (Gypohierax angolensis) (which was once widely referred to as the "vulturine fish eagle"). The relation of these species to the sea eagles is partially borne out by their genetic sequencing. Other groups, beyond milvine kites and Old World vulture, of modern accipitrids that are seemingly in some way related, albeit distantly, to the sea eagles include Accipiters, harriers, chanting-goshawks and buteonines. Notably excluded from their relations are most other species referred to as "eagles", including booted eagles and snake and serpent eagles.<p>The white-tailed eagle itself forms a species pair with the bald eagle. These diverged from other sea eagles at the beginning of the early Miocene (c. 10 mya) at the latest, possibly (if the most ancient fossil record is correctly assigned to this genus) as early as the early or middle Oligocene, about 28 mya. A recent genetic study of mitochondrial DNA is consistent with this idea. Greenlandic white-tailed eagles (proposed as H. a. groenlandicus) form, on evolutionary time scales, a relatively recently founded population that has not yet accumulated many unique genetic characteristics and may not strictly fulfill the distinction of a subspecies. However, the population appears to be demographically isolated and deserves special protection. At one time an eastern subspecies (H. a. brooksi) was proposed as well but there is little evidence supporting this as more than a case of clinal variation in colouring and size (i.e. the eastern average slightly darker and smaller than more westerly ones). As in other sea-eagle species pairs, this one consists of a white-headed (the bald eagle) and a tan-headed species. They probably diverged in the North Pacific, spreading westwards into Eurasia and eastwards into North America. Like the third large northern species, Steller's sea eagle (Haliaeetus pelagicus), adults have yellow feet, beaks and eyes. Another species, likely intermediate between the white-tailed, bald and Steller's sea eagles and the Ichthyophaga type fish eagles, is the Pallas's fish eagle (Haliaeetus leucoryphus), which in life history seems to range farther from water and to higher elevations than the three northern species normally do. Due to the similar dietary and nesting habits of sea eagles, they are mostly allopatric in distribution as competition can be considerable between these eagles.<p>Currently, eagles occur in the Hawaiian Islands only as vagrants, but Quaternary bones of Haliaeetus have been found on three of the major islands. An ancient DNA study published in 2015 characterized the rapidly evolving mitochondrial control region of one of these specimens. DNA from a ~3,500-year-old sea eagle skeleton found in a lava cave on Maui was sequenced. Phylogenetic analyses suggested that the Hawaiian eagle represents a distinct (&gt;3% divergent) mtDNA lineage that is most closely related to extant white-tailed eagles. Based on fossil calibration, the Hawaiian mtDNA lineage probably diverged around the Middle Pleistocene. Thus, although not clearly differentiated in morphology from its relatives, the Hawaiian eagle likely represented an isolated, resident population in the Hawaiian archipelago for more than 100,000 years, where it was the largest terrestrial predator. The reasons for its extinction are unknown.

Wissenschaftlicher Name

Haliaeetus albicilla

Autorität

(Linnaeus, 1758)

Ordnung

Accipitriformes

Familie

Accipitridae

Gattung

Haliaeetus

Verbreitung und Lebensraum

This eagle breeds in northern Europe and northern Asia. Their range extends to as far west as southern Greenland (prevented from breeding further north due to the short summers), northern and western Iceland, and the reintroduced populations in some areas of England (re-established in 2019), Ireland and Scotland, particularly conserved coastal spots. In mainland Europe the range is expanding, with Europe's largest population breeding in coastal Norway (broadly), northern and southwestern Finland, eastern Sweden, broadly in Denmark, islands of the Baltic Sea, western Austria, northeastern Germany, northern and eastern Poland, the Czech Republic, much of the east Baltic countries, the non-montane areas of Ukraine, eastern Slovenia, central and southern Hungary (and adjacent northeastern Croatia), sporadically in Greece, the Danube sections of Romania and Bulgaria to the Black Sea and western and eastern Moldova. The bird returned to the Netherlands in 2006 and in 2020 the number of breeding pairs had increased to 20. It might have bred in the Faroe Islands up until the 17th century, but evidence is lacking; there are only about a dozen records of vagrant white-tailed eagles from the archipelago since 1800.<p>In Anatolia, it only remains as a breeder in sparse and small pockets of Turkey and Georgia, taken as a region there are likely to be fewer than 30 breeding pairs in this region. In the Middle East, the white-tailed eagle may still be found breeding only along the southern coast of the Caspian Sea in northern Iran and southwestern Turkmenistan. Discontinuously, they are found as residents in Kazakhstan where they live in a long strip of the southern part of the country starting at the Aral Sea and the northwestern portion (but not, as far as is known, breeding in the Kazakh part of the Caspian Sea coast). The only country in which the white-tailed eagle is found over a continuous and extremely large area is Russia. The species is found broadly everywhere in Russia from European Russia in the west to the Bering Sea in the east, only being fully absent as a nester as far as is known from the high Arctic regions and a section bordering westernmost Kazakhstan, although it breeds to south of this in the Russian coastal part of the Caspian Sea. Their northern limits occur in Russia to the Ob river to 70 degrees north at the mouth of the Yenisei River and on the Gyda and Yamal Peninsulas, to the Kolyma, Indigirka and Lena rivers to above 72 degrees north, even to 75 degrees north on the Taymyr Peninsula. They are said to be common around the White Sea, reportedly even the most abundant bird of prey locally and found both on coasts and inland lakes, although breeding rates are low due to the frigid weather. From Russia, breeding populations spill somewhat into northernmost Mongolia, extreme northwestern China and northern North Korea. The white-tailed eagle also breeds on Sakhalin Island, the Kuril Islands and Hokkaido, the northernmost island of Japan.<p>The wintering range is less well understood for the white-tailed eagle given the extreme reductions and fluctuations of northern breeding populations over the last few centuries, so that the delineation of regular wintering areas versus areas of mere vagrancy is difficult to ascertain. It is known that a small number winter on Etang de Lindre of Lorraine, France as well as an area on the border of France to Germany around Strasbourg, with vagrants to elsewhere in France, as well as to Spain, Portugal and Malta. A well-defined wintering population may occur in much of the Netherlands, even with infrequent modern breeding in the northern coastal areas. A wintering population is known in western Germany from North Rhine-Westphalia to Bonn, as well as far northern Germany. In Denmark, they both breed and winter throughout much of the country, but in particular the Wadden Sea region attracts many white-tailed eagles, mostly immatures, from elsewhere in Denmark and neighbouring countries during the winter. Other established wintering areas are known in Europe in west-central Italy, northern Austria, fairly broadly in southern Slovakia and northern Hungary and a few protected pockets of Southeast Europe apart from the portions in the north and east where they still breed. <p>Intermittent forms of vagrancy and migration (most from eagles that breed in or disperse from Russia) are known to occur in several areas of Turkey, the Levant countries, Azerbaijan and Iran down to even the Persian Gulf, albeit seldom is the species to be found commonly or reliably anywhere in these regions. Further east, rare wintering areas are known in a few small, scarce pockets of Turkmenistan, Afghanistan, Uzbekistan, Tajikistan and Pakistan. It is a rare winter visitor to India, namely the extreme northwest and along the border of Nepal to Bhutan and extreme northern Bangladesh. Scattered pockets of wintering birds are known to occur too in central and southern China, into northeastern Myanmar, and more broadly and regularly in much of Northeast China. Good numbers winter too in much of South Korea and Japan down to as far as Honshu. White-tailed eagles dispersing from their breeding grounds or natal sites in the Russian Far East are known to occasionally disperse across the Bering Sea to North America in several parts of the Aleutian Islands, the Pribilof Islands and some of mainland coastal Alaska down to Kodiak Island. Some white-tailed eagles even bred in Alaska on Attu Island in the late 1970s to the early 1980s (until 1984 when the last attempts were recorded) but it was not clear whether young were ever successfully fledged.<p>White-tailed eagles may be found in varied habitat but usually are closely associated with water and generally occurs in lowland areas. Although mainly a lowland species, the species is known to live at elevations of 1,500 to 2,300 m (4,900 to 7,500 ft) so long as there is water access in some parts of Central Asia and Siberia. In coastal areas, the species may range from high sea cliffs down to low-lying islands and archipelagos. Especially in winter, many white-tailed eagles often frequent low coastal spots, estuaries and coastal marshes. Several studies have supported that coastal areas are preferred when available during winter. In many areas, white-tailed eagles can seem to switch freely between usually cliff habitat and wooded spots for nesting sites and the center of their home range habitat. In some areas, such as Japan, this species may occur in regions with intensive human fishing activity and they may become unusually partially habituated to this human presence. Inland, white-tailed eagles usually require secluded woods, forested areas or groups of trees with tall mature trees and access to freshwater wetlands such as lakes, river systems, marshes or extensive, low-disturbance farmland. In the alluvial wetlands of Croatia, 95% of nests were found within 4 km (2.5 mi) of deep freshwater.<p>In some areas, white-tailed eagles readily visit commercial fish farms, carp ponds and similar areas with easily accessible food but they will usually avoid areas where human disturbances (especially noisy varieties such as construction, water sporting and heavy boating activities and hunting) commonly occur. However, forestry activity and resulting lessened numbers of tall mature trees and large tree stands in Estonia was found to affect breeding white-tailed eagles less so than it seemed to affect breeding black storks (Ciconia nigra). On the other hand, from studying wintering white-tailed eagles in partially or heavily disturbed wetlands in parts of the Netherlands shows that such areas cannot support the eagles for any long-term period and may only be visited for a day or two by individual eagles. Conversely, reviews of the rapidly increasing Danish population have found that when well-protected, they may regularly forage in habitats near significant humans populations, even in the outskirts of cities, and they can also successfully breed in such locations.

Zugverhalten

Complete migrants

Verhalten

White-tailed eagles spend much of their day perched on trees or crags, and may often not move for hours. Perhaps up to 90% of a day may be spent perched, especially if weather is poor. Also, they will alternate periods of soaring with perching, especially flying over water or well-watered areas, but do considerably less soaring on average than do golden eagles. Pairs regularly roost together, often near to their nest, either on a crag or tree or crevices, overhung ledges or small isolated trees on a crag.<p>The white-tailed eagle may be considered a rather inconsistent and partial migrant. The species seldom migrates in the western part of its range, with eagles even breeding as far north as Greenland, Iceland and coastal Norway not moving at all for winter, but for some southward juvenile movements following dispersal. Juveniles overall are more migratory and dispersive and leave natal areas sooner, which is by August–September in northwestern Europe and return later, by March/April, than adults do. Few Norwegian juveniles, per banding studies, were recorded to travel any considerable distance. Extreme cases include one that was found 720 km (450 mi) south of its nest near Karlstad, Sweden, another set of four colour-marked first-year juveniles were also recorded to turn up in southern Sweden but one was found down to the Wadden Sea in the Netherlands and it is likely that trickling down numbers of Norwegian post-dispersal juveniles have gone onto form much of the known Dutch white-tailed eagle population. In contrast, young from Finland and Sweden tend to distribute to the southwesterly direction to the shores of the Baltic Sea. One from Finland was recovered 520 km (320 mi) west in northern Norway and another was found as far south as Bulgaria. In more southerly areas, winter movements are drawn-out and irregular, with most mature pairs probably never leaving their nesting haunts year-around. Those that breed on inland waterways may migrate to sea coast. German juveniles usually do not travel far, with most recorded to travel less than 50 km (31 mi) from their nests and a majority staying near the Baltic coast. However, some eagles that hatched from nests in Germany have been found as far south as in Italy, 1,030 km (640 mi) away to the southeast, or to Gironde, France, 1,520 km (940 mi) to the southwest. In several parts of Russia, quite unlike many European populations, the white-tailed eagle seems to be largely migratory. <p>In the far east, the species appear to take different migratory routes in autumn and spring, traveling from north-central Kamchatka thru the Kurile islands to Hokkaido in autumn, while in spring these eagles travel north through Sakhalin and the Okhotsk Coast. In the White Sea area, southward moments begin in September with most white-tailed eagles being gone by November but in mild winters some adults may remain behind. Some white-tailed eagles from the White Sea were found well over 2,000 km (1,200 mi) away to the west, in countries such as Hungary and Italy. Return spring migration to the White Sea is by February–March. During winter, whether long-distance migrants or short-distance dispersers, white-tailed eagles tend to become gregarious, especially younger immature birds. Many such groups can contain up to 10 and, in areas near large breeding populations such as the Scandinavian countries, up to at least 30–50 individuals. Wintering congregations at the Baltic coast and on the River Elbe from 37 winters show that arrivals begin in November, with numbers peaking in January and then declining during March and early April. Although juveniles usually return to their natal area some apparently overshoot these areas, such as those returning to Romania or on the Black Sea which have been recorded 330 km (210 mi) north of their natal site and 510 km (320 mi) northeast of their natal site.<p>Territory size in white-tailed eagles may vary from 52 to 415 km2 (20 to 160 sq mi), usually less than 130 km2 (50 sq mi), per one estimate. However, home ranges in northeastern Germany were much smaller than this, at 2.25 to 19.16 km2 (0.87 to 7.40 sq mi). While territorial behaviour is known in well more than half of all modern birds, essentially all predatory birds of different lineages are particularly strongly territorial because the live prey necessary to feed a family, including the female of the pair (which must remain near the young for them to survive) and the young themselves, tends to be sparser. Furthermore, appropriate habitat is needed in which to execute this hunting and also, of course, to build a nest with some security. Although a relatively gregarious raptor, especially among wintering birds and juveniles and immature birds, they are territorial and intrusion by a male in adult plumage often provokes vigorous fighting, in which either combatant can even die. In some cases, these vicious fights can cause damage to the nest as the two fighting eagles plummet down trying to slash at each other.

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