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The white-tailed eagle (''Haliaeetus albicilla'') is a very large species of
sea eagle A sea eagle or fish eagle (also called erne or ern, mostly in reference to the white-tailed eagle) is any of the birds of prey in the genus ''Haliaeetus'' in the bird of prey family Accipitridae. Taxonomy and evolution The genus ''Haliaeetus'' ...
widely distributed across temperate
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
. Like all eagles, it is a member of the family Accipitridae (or accipitrids) which includes other diurnal
raptor Raptor or RAPTOR may refer to: Animals The word "raptor" refers to several groups of bird-like dinosaurs which primarily capture and subdue/kill prey with their talons. * Raptor (bird) or bird of prey, a bird that primarily hunts and feeds on v ...
s such as
hawk Hawks are birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica. * The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. This subfa ...
s, kites, and harriers. One of up to eleven members in the genus '' Haliaeetus'', which are commonly called sea eagles, it is also referred to as the white-tailed sea-eagle.Helander, B., & Stjernberg, T. (2003). ''Action plan for the conservation of white-tailed sea eagle (''Haliaeetus albicilla'')''. In Convention on the Conservation of European Wildlife and Natural Habitats, Strasbourg, France. Sometimes, it is known as the ern or erne (depending on spelling by sources),Love, J. A. (1983). ''The return of the Sea Eagle''. Cambridge University Press, . gray sea eagle and Eurasian sea eagle. While found across a very wide range, today breeding as far west as
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
and
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
across to as far east as
Hokkaido is Japan, Japan's Japanese archipelago, second largest island and comprises the largest and northernmost Prefectures of Japan, prefecture, making up its own List of regions of Japan, region. The Tsugaru Strait separates Hokkaidō from Honshu; th ...
,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
, they are often scarce and very spottily distributed as a nesting species, mainly due to human activities. These have included habitat alterations and destruction of
wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
s, about a hundred years of systematic persecution by humans (from the early 1800s to around
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
) followed by inadvertent poisonings and epidemics of nesting failures due to various manmade chemical
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...
s and
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
s, which have threatened eagles since roughly the 1950s and continue to be a potential concern. Due to this, the white-tailed eagle was considered endangered or extinct in several countries. However, some populations have recovered well due to some governmental protections and dedicated
conservationists The conservation movement, also known as nature conservation, is a political, environmental, and social movement that seeks to manage and protect natural resources, including animal, fungus, and plant species as well as their habitat for the ...
and naturalists protecting habitats and nesting sites and partially regulating poaching and pesticide usage, as well as careful reintroductions into parts of their former range.Love, J. A. (1988). ''The reintroduction of the white-tailed sea eagle to Scotland: 1975–1987''. Nature Conservancy Council. White-tailed eagles usually live most of the year near large bodies of open water, including coastal saltwater areas and inland
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s, wetlands,
bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
s and
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
s. It requires old-growth trees or ample sea cliffs for nesting, and an abundant food supply of
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
and
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s (largely water birds) amongst nearly any other available prey. Both a powerful apex predator and an opportunistic
scavenger Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feedin ...
, it is considered a close cousin of the
bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...
(''Haliaeetus leucocephalus''), which occupies a similar
niche Niche may refer to: Science *Developmental niche, a concept for understanding the cultural context of child development * Ecological niche, a term describing the relational position of an organism's species *Niche differentiation, in ecology, the ...
in North America.


Taxonomy

The first formal description of the white-tailed eagle was by the Swedish naturalist
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...
in 1758 in the tenth edition of his ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial ...
'' under the
binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...
''Falco albicilla''. The
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
'' Haliaeetus'' was introduced in 1809 by the French naturalist Marie Jules César Savigny in the '' Description de l'Égypte''. The name ''Haliaeetus'' is New Latin for "sea-eagle", from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
''hali-'', "sea-" and ''aetos'', "eagle". The specific ''albicilla'', "white-tailed", is from New Latin ''albi-'', "white" and ''cilla'', "tail". The
Anglo-Saxon The Anglo-Saxons were a cultural group who inhabited England in the Early Middle Ages. They traced their origins to settlers who came to Britain from mainland Europe in the 5th century. However, the ethnogenesis of the Anglo-Saxons happened wit ...
name ''erne'' means "soarer", and it is
cognate In historical linguistics, cognates or lexical cognates are sets of words in different languages that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical ef ...
to Swedish ''örn'' and Finnish ''aarni''. It has many Gaelic names, including ''iolar sùil na grèine'' or 'eagle of the sun's eye.'


Systematics

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, comprised by the
lesser Lesser, from Eliezer (, "Help/Court of my God"), is a surname. Notable people with the surname include: * Adolf Lesser (1851–1926), German physician * Aleksander Lesser (1814–1884), Polish painter and art critic * Anton Lesser (born 1952), Br ...
(''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.Seibold, I., & Helbig, A. J. (1996). ''Phylogenetic relationships of the sea eagles (genus Haliaeetus): reconstructions based on morphology, allozymes and mitochondrial DNA sequences''. Journal of Zoological Systematics and Evolutionary Research, 34(2), 103–112.Griffiths, C. S., Barrowclough, G. F., Groth, J. G., & Mertz, L. A. (2007). ''Phylogeny, diversity, and classification of the Accipitridae based on DNA sequences of the RAG‐1 exon''. Journal of Avian Biology, 38(5), 587–602. Other than these ''Ichthyophaga''-type species found farther north in Asia,
Sanford's sea eagle Sanford's sea eagle (''Haliaeetus sanfordi''), also known as Sanford's fish eagle or the Solomon eagle, is a sea eagle endemic to the Solomon Islands archipelago. Taxonomy Sanford's sea eagle was discovered by and named after Dr Leonard C. Sa ...
(''Haliaeetus sanfordi'') of the
Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capit ...
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
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s and
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...
s rather than
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
and water birds. Outside of the genus ''Haliaeetus'', among other extant forms, they appear to be most closely related to milvine kites and
Old World vulture Old World vultures are vultures that are found in the Old World, i.e. the continents of Europe, Asia and Africa, and which belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks. Old World vultures are not cl ...
s, 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 The palm-nut vulture (''Gypohierax angolensis'') or vulturine fish eagle, is a large bird of prey in the family Accipitridae (which also includes many other diurnal raptors such as kites, buzzards and harriers, vultures, and eagles). It is the ...
(''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.Wink, M., & Sauer-Gürth, H. (2004). ''Phylogenetic relationships in diurnal raptors based on nucleotide sequences of mitochondrial and nuclear marker genes''. Raptors worldwide, pp. 483–498. Other groups, beyond milvine kites and Old World vulture, of modern accipitrid that are seemingly in some way related, albeit very 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. The white-tailed eagle itself forms a species pair with the
bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...
. These diverged from other sea eagles at the beginning of the early
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
(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 The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...
, about 28  mya. A recent genetic study of
mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
is consistent with this idea. Greenlandic white-tailed eagles (proposed as ''H. a. groenlandicus'') form, on
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
ary 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 coloring 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 North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
. 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 Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
in distribution as competition can be considerable between these eagles. Currently, eagles occur in the
Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost ...
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 The island of Maui (; Hawaiian: ) is the second-largest of the islands of the state of Hawaii at 727.2 square miles (1,883 km2) and is the 17th largest island in the United States. Maui is the largest of Maui County's four islands, whic ...
was sequenced. Phylogenetic analyses suggested that the Hawaiian eagle represents a distinct (>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.


Description


Size

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 The Russian Far East (russian: Дальний Восток России, r=Dal'niy Vostok Rossii, p=ˈdalʲnʲɪj vɐˈstok rɐˈsʲiɪ) is a region in Northeast Asia. It is the easternmost part of Russia and the Asian continent; and is admin ...
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 in total length with a typical wingspan of . 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. Average wingspans are not known for the Steller's species, however white-tailed eagles do appear to outsize the average wingspan of the
wedge-tailed eagle The wedge-tailed eagle (''Aquila audax'') is the largest bird of prey in the continent of Australia. It is also found in southern New Guinea to the north and is distributed as far south as the state of Tasmania. Adults of this species have lo ...
(''Aquila audax''), which is sometimes also titled the largest winged extant eagle (however one wedge-tail did possess the largest wingspan ever verified for an extant eagle). In one sample from
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...
, five male white-tailed eagles were found to average and eight females were found to average .Willgohs, J. F. (1961). ''The white-tailed eagle ''Haliaëtus albicilla albicilla'' (Linné) in Norway''. Norwegian Universities Press. In another sample of wild birds of unspecified origin, five males were found to average and seven females averaged . Record wingspans have included a specimen from Greenland which measured while another specimen apparently spanned . 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.Friedmann, H. (1950). ''Birds of North and Middle America, Pt. 2''. U.S. Nat. Mus. Bull. no. 50.Imler, R. H., & Kalmbach, E. R. (1955). ''The Bald Eagle and its economic status (Vol. 30)''. US Government Printing Office. 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 Bergmann's rule is an ecogeographical rule that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer r ...
in that more northerly birds tend to outsize those found relatively closer to the
Equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...
. Average size also decreases from west to east across its distribution.Zhengjie, Z. (2001). ''Birds of China, Vol.1 (Non-Sparrow-shaped)'': Jilin Science and Technology Press: 275–276 The largest white-tailed eagles appear to be found in
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
, these being slightly larger than those from
Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...
and
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and S ...
and notably larger than eagles from
central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the a ...
, especially in proportions of the wing area. Those from the southerly portions of the breeding range, such as
Asia Minor Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
(principally
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula ...
), southern
Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
, and
Korea Bay The Korea Bay, sometimes the West Korea Bay (; ; or ), is a bight and the northern extension of the Yellow Sea, between the southeastern coastline of China's Liaoning province and the western coastline of North Korea's North Pyongan, South ...
, 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.Cramp, S., & Brooks, D. J. (1992). ''Handbook of the birds of Europe, the Middle East and North Africa. The birds of the western Palearctic''. Oxford University Press, Oxford. In the white-tailed eagle, body mass can typically range from in females. The slightly smaller male may typically weigh from . Average weights in European white-tailed eagles can range from in five males and in nine females to (from the reintroduced birds of Scotland of Norwegian stock) in 39 males and in 43 females. In comparison, the weight ranges for white-tailed eagles from
Northeast China Northeast China or Northeastern China () is a geographical region of China, which is often referred to as "Manchuria" or "Inner Manchuria" by surrounding countries and the West. It usually corresponds specifically to the three provinces east of ...
were claimed to be only in males and in females. The heaviest female white-tailed eagles can apparently weigh as much as and even males can sometimes weigh up to , which would make the largest males perhaps the heaviest recorded modern male eagle, as male harpy and Philippine eagles (being more sexually dimorphic in favor of the female) are not known to exceed (the highest weights for male Steller's sea eagle are not known).''CRC Handbook of Avian Body Masses, 2nd Edition'' by John B. Dunning Jr. (Editor). CRC Press (2008), . The global mean body mass of white-tailed eagles is estimated at approximately . 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.


Standard measurements and sexual dimorphism

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 in males, averaging in European adults and juveniles, respectively, and in Greenland males. In females, the wing chord may measure , averaging in European adults and juveniles, respectively, and in Greenland females. Adult
tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...
length is in males, averaging , and in females, averaging . Juvenile tail lengths can reach roughly in both sexes, however. The tarsus is , averaging . In terms of their killing apparatuses, their hallux claw, the largest talon on all accipitrids, is in length, averaging . The hallux claw averages about a centimeter less than that of a
golden eagle The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known bird ...
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 and of similar curvature.Zylo, M. T. (2012). ''Bald eagles (Haliaeetus leucocephalus) wintering in northern Arizona select perches based on food availability, visibility and cover'' (Doctoral dissertation, Northern Arizona University). The exposed culmen is typically large as in all ''Haliaeetus'', ranging from , with an average of . The average culmen length of the bald eagle is , 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 and can even rival the length (but perhaps not the girth) of the truly massive bill of the Steller's sea eagle.


Coloring and field appearance

The adult white-tailed eagle is a greyish mid-brown color overall. The plumage is fairly uniform over most of the body and wings, but the upper wing
coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are ...
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 Buff or BUFF may refer to: People * Buff (surname), a list of people * Buff (nickname), a list of people * Johnny Buff, ring name of American world champion boxer John Lisky (1888–1955) * Buff Bagwell, a ring name of American professional w ...
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 grayish. 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 molted, 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 color, 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. 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 color with messy blackish color 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 gray 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. 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 coloring 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 molt in May/June until October/November at just over one year of age. Their second molt is the following year in March or April, with two more subsequent molts usually beginning around this time for the next couple of years. Like other large raptors, feathers are molted at slow intervals so as not to inhibit food capture. Only relatively small proportions of the flight feathers are molted each year. Molting occurs more or less continuously, although it may pause in winter if food is in short supply. 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.Forsman, D. (1999). ''The raptors of Europe and the Middle East: a handbook of field identification''. London: T & AD Poyser. 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 The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it conn ...
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 herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychu ...
. 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.Porter, R. F. (1981). ''Flight identification of European raptors''. A&C Black.


Vocalizations

The white-tailed eagle is considered a very 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 ' or ', while the female is a deeper ' or '. 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 ' 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 '. Typically, the perched version of their calls tend to be shriller and higher than those issued in flight. In courtship display, male calls ' answered by females with a lower '. Young in nest call a shrilly ', while the female when receiving food from male calls out with ' or '. Single or repeated ' or similar component of calls used in other circumstances, but this can be very variable. Alarm calls tend to be 3–4 short, loud ' or ' notes. Sometimes a different call of alarm or anger, a deep ' or ', similar to alarm calls of a large
gull Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century ...
, is also uttered when a nest is approached (usually recorded while directed towards humans). The young let out a monotonous ' when hungry (or "bored") which intensifies if the eaglets are not fed or brooded immediately.Mecionis, R., & Jusys, V. (1994). ''The White-Tailed Eagle ''Haliaeetus albicilla'' at Kursiu Lagoon''. Acta Orn. Lituanica, pp. 9–10.


Identification

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 obviously very 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 color contrast is far subtler in white-tailed eagles between their brown body (of a paler hue than that of a bald eagle) and buff-colored head. At a great distance, the adult may be potentially confusable with the Griffon vulture (''Gys fulvus''), as the coloring 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. Juveniles may be harder to distinguish, mainly from other sea eagles in few areas of overlap. In northern
Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million ...
(perhaps spilling over into southern
Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part ...
), the northern part of the
Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central A ...
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 The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large v ...
(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 coloring, 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.Howell, S. N., Lewington, I., & Russell, W. (2014). ''Rare Birds of North America''. Princeton University Press. 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 color is similar at the various stages of development but the shape is more distinctive, especially the bolder wedge shape of the Steller's. 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.Clark, W. S. (1999). ''A field guide to the raptors of Europe, the Middle East, and North Africa''. Oxford University Press, USA.Naoroji, R., & Schmitt, N. J. (2007). ''Birds of prey of the Indian subcontinent''. Om Books International. 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.


Distribution and habitat


Breeding range

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 Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
, and the reintroduced populations in some areas of
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
(re-established in 2019),
Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...
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 Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bot ...
,Stjernberg, T. (1981). ''Projekt havsörn i Finland.–I Stjernberg, T.(red.): Projekt havsörn i Finland och Sverige''. Förhandlingar från ett havsörnssymposium 8–9.1. 1979 på Tvärminne Zoologiska station, Finland. Luonnonvarainhoitotoimiston julkaisuja (Helsinki), 3, 31–60. eastern
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
, broadly in
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of Denmark , establish ...
,Ehmsen, E., Pedersen, L., Meltofte, H., Clausen, T., & Nyegaard, T. (2011). ''The occurrence and reestablishment of White-tailed Eagle and Golden Eagle as breeding birds in Denmark''. Dansk Ornitologisk Forenings Tidsskrift, 105(2), 139. islands of the
Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...
, western
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
, northeastern
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
, northern and eastern
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
,Bogucki, Z. (1976). ''Status of the White-tailed Eagle in Poland''. In W: Report of WWF symposium on the White-tailed Eagle (pp. 31–32). the Czech Republic, much of the east Baltic countries, the non-montane areas of
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inva ...
, eastern
Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, and ...
, central and southern
Hungary Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Cr ...
(and adjacent northeastern
Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = " Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capi ...
), very sporadically in
Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wi ...
, the Danube sections of
Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...
and
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
to the
Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Rom ...
and western and eastern
Moldova Moldova ( , ; ), officially the Republic of Moldova ( ro, Republica Moldova), is a landlocked country in Eastern Europe. It is bordered by Romania to the west and Ukraine to the north, east, and south. The unrecognised state of Transnistri ...
.Bijleveld, M. F. (1974). ''Birds of prey in Europe''. Macmillan. The bird returned to the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
in 2006 and in 2020 the number of breeding pairs had increased to 20. In
Anatolia Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
, it only remains as a breeder in very 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 Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...
, the white-tailed eagle may still be found breeding only along the southern coast of the Caspian Sea in northern
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
and southwestern
Turkmenistan Turkmenistan ( or ; tk, Türkmenistan / Түркменистан, ) is a country located in Central Asia, bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the s ...
.Firouz, E. (2005). ''The complete fauna of Iran''. IB Tauris. 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 The Aral Sea ( ; kk, Арал теңізі, Aral teñızı; uz, Орол денгизи, Orol dengizi; kaa, Арал теңизи, Aral teńizi; russian: Аральское море, Aral'skoye more) was an endorheic lake lying between Kazak ...
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 Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
. The species is found very broadly everywhere in Russia from
European Russia European Russia (russian: Европейская Россия, russian: европейская часть России, label=none) is the western and most populated part of Russia. It is geographically situated in Europe, as opposed to the cou ...
in the west to the
Bering Sea The Bering Sea (, ; rus, Бе́рингово мо́ре, r=Béringovo móre) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasses on Earth: Eurasia and The Am ...
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.Knystautas, A. (1993). ''Birds of Russia''. HarperCollins. Their northern limits occur in Russia to the
Ob river } The Ob ( rus, Обь, p=opʲ: Ob') is a major river in Russia. It is in western Siberia; and together with Irtysh forms the world's seventh-longest river system, at . It forms at the confluence of the Biya and Katun which have their origins ...
to 70 degrees north at the mouth of the
Yenisei River The Yenisey (russian: Енисе́й, ''Yeniséy''; mn, Горлог мөрөн, ''Gorlog mörön''; Buryat: Горлог мүрэн, ''Gorlog müren''; Tuvan: Улуг-Хем, ''Uluğ-Hem''; Khakas: Ким суғ, ''Kim suğ''; Ket: Ӄук, ...
and on the Gyda and Yamal Peninsulas, to the
Kolyma Kolyma (russian: Колыма́, ) is a region located in the Russian Far East. It is bounded to the north by the East Siberian Sea and the Arctic Ocean, and by the Sea of Okhotsk to the south. The region gets its name from the Kolyma River ...
,
Indigirka The Indigirka ( rus, Индиги́рка, r=; sah, Индигиир, translit=Indigiir) is a river in the Sakha Republic in Russia between the Yana to the west and the Kolyma to the east. It is long. The area of its basin is . History The i ...
and
Lena river The Lena (russian: Ле́на, ; evn, Елюенэ, ''Eljune''; sah, Өлүөнэ, ''Ölüöne''; bua, Зүлхэ, ''Zülkhe''; mn, Зүлгэ, ''Zülge'') is the easternmost of the three great Siberian rivers that flow into the Arctic Ocean ...
s to above 72 degrees north, even to 75 degrees north on the Taymyr Peninsula. They are said to be common around the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
, 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.Flerov, A. I. (1970). ''The ecology of the White-tailed Eagle of the Kandalaksha Bay''. Proceeding of the Kandalaksha State Nature Reserve, No. VII: 215–232. From Russia, breeding populations spill somewhat into northernmost Mongolia, extreme northwestern
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
and northern
North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and shares borders with China and Russia to the north, at the Yalu (Amnok) and T ...
. The white-tailed eagle also breeds on
Sakhalin Island Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh ...
, the
Kuril Islands The Kuril Islands or Kurile Islands (; rus, Кури́льские острова́, r=Kuril'skiye ostrova, p=kʊˈrʲilʲskʲɪjə ɐstrɐˈva; Japanese language, Japanese: or ) are a volcanic archipelago currently administered as part of Sakh ...
and Hokkaido, the northernmost island of Japan.


Wintering range

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 France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
as well as an area on the border of France to Germany around
Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label= Bas Rhin Alsatian, Strossburi , gsw, label= Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the ...
, with vagrants to elsewhere in France, as well as to
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...
,
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of th ...
and
Malta Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...
.Bent, A. C. (1937). ''Life histories of North American birds of prey''. US Government Printing Office. A well-defined wintering population may occur in much of the Netherlands, even with infrequent modern breeding in the northern coastal areas.Rijn, S. V., Zijlstra, M., & Bijlsma, R. G. (2010). ''Wintering white-tailed eagles ''Haliaeetus albicilla'' in The Netherlands: aspects of habitat scale and quality''. Ardea, 98(3), 373–382. A non-breeding population is known in western Germany from
North Rhine-Westphalia North Rhine-Westphalia (german: Nordrhein-Westfalen, ; li, Noordrien-Wesfale ; nds, Noordrhien-Westfalen; ksh, Noodrhing-Wäßßfaale), commonly shortened to NRW (), is a state (''Land'') in Western Germany. With more than 18 million inha ...
to
Bonn The federal city of Bonn ( lat, Bonna) is a city on the banks of the Rhine in the German state of North Rhine-Westphalia, with a population of over 300,000. About south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ru ...
, as well as far northern Germany into southwestern Denmark. Other established wintering areas are known in Europe in west-central
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, northern Austria, fairly broadly in southern
Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the ...
and northern Hungary and a few protected pockets of Southeast Europe apart from the portions in the north and east where they still breed. 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 The Levant () is an approximate historical geographical term referring to a large area in the Eastern Mediterranean region of Western Asia. In its narrowest sense, which is in use today in archaeology and other cultural contexts, it is ...
countries,
Azerbaijan Azerbaijan (, ; az, Azərbaycan ), officially the Republic of Azerbaijan, , also sometimes officially called the Azerbaijan Republic is a transcontinental country located at the boundary of Eastern Europe and Western Asia. It is a part of th ...
and Iran down to even the
Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a mediterranean sea in Western Asia. The bo ...
, 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 Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is borde ...
,
Uzbekistan Uzbekistan (, ; uz, Ozbekiston, italic=yes / , ; russian: Узбекистан), officially the Republic of Uzbekistan ( uz, Ozbekiston Respublikasi, italic=yes / ; russian: Республика Узбекистан), is a doubly landlocked co ...
,
Tajikistan Tajikistan (, ; tg, Тоҷикистон, Tojikiston; russian: Таджикистан, Tadzhikistan), officially the Republic of Tajikistan ( tg, Ҷумҳурии Тоҷикистон, Jumhurii Tojikiston), is a landlocked country in Centr ...
and
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
. It is a very rare winter visitor to
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
, namely the extreme northwest and along the border of
Nepal Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is ma ...
to
Bhutan Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainou ...
and extreme northern
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mo ...
. Scattered pockets of wintering birds are known to occur too in
central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...
and southern China, into northeastern
Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
, and more broadly and regularly in much of Northeast China.Brazil, M. (2009). ''Birds of East Asia: China, Taiwan, Korea, Japan, and Russia''. A&C Black. Good numbers winter too in much of
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
and Japan down to as far as
Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island s ...
. 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 Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large v ...
, the
Pribilof Islands The Pribilof Islands (formerly the Northern Fur Seal Islands; ale, Amiq, russian: Острова Прибылова, Ostrova Pribylova) are a group of four volcanic islands off the coast of mainland Alaska, in the Bering Sea, about north o ...
and some of mainland coastal
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
down to Kodiak Island. Some white-tailed eagles even bred in
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
on
Attu Island Attu ( ale, Atan, russian: Атту, link=no) is an island in the Near Islands (part of the Aleutian Islands chain). It is the westernmost point of the U.S. state of Alaska. The island became uninhabited in 2010, making it the largest uninhabit ...
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.


Habitat

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 so long as there is water access in some parts of
Central Asia Central Asia, also known as Middle Asia, is a region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes the fo ...
and
Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part ...
. In coastal areas, the species may range from high sea
cliff In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on co ...
s down to low-lying
island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An isla ...
s and
archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arch ...
s. Especially in winter, many white-tailed eagles often frequent low coastal spots,
estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...
and coastal marshes. Several studies have supported that coastal areas are preferred when available during winter.Treinys, R., Dementavičius, D., Rumbutis, S., Švažas, S., Butkauskas, D., Sruoga, A., & Dagys, M. (2016). ''Settlement, habitat preference, reproduction, and genetic diversity in recovering the white-tailed eagle ''Haliaeetus albicilla'' population''. Journal of Ornithology, 157(1), 311–323. 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.Evans, R. J., Pearce‐Higgins, J., Whitfield, D. P., Grant, J. R., MacLennan, A., & Reid, R. (2010). ''Comparative nest habitat characteristics of sympatric White‐tailed ''Haliaeetus albicilla'' and Golden Eagles ''Aquila chrysaetos'' in western Scotland''. Bird Study, 57(4), 473–482. In some areas, such as Japan, this species may occur in regions with intensive human
fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment, but may also be caught from fish stocking, stocked bodies of water such as fish pond, ponds, canals, park wetlands and reservoirs. ...
activity and they may become unusually partially habituated to this human presence.Tingay, R. E., & Katzner, T. E. (Eds.). (2010). ''The eagle watchers: Observing and conserving raptors around the world''. Cornell University Press. Inland, white-tailed eagles usually require secluded woods, forested areas or groups of trees with tall mature trees and access to freshwater
wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
s such as
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s, river systems,
marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...
es or extensive, low-disturbance farmland. In the alluvial wetlands of Croatia, 95% of nests were found within of deep freshwater.Radović, A., & Mikuska, T. (2009). ''Population size, distribution and habitat selection of the white-tailed eagle ''Haliaeetus albicilla'' in the alluvial wetlands of Croatia''. Biologia, 64(1), 156–164. 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 Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and ...
, water sporting and heavy
boating Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels (such as rowing and paddle boats), focused on the travel itself, as well as sports activities, suc ...
activities and
hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
) commonly occur. However, forestry activity and resulting lessened numbers of tall mature trees and large tree stands in
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
was found to affect breeding white-tailed eagles less so than it seemed to affect breeding black storks (''Ciconia nigra'').Rosenvald, R., & Lõhmus, A. (2003). ''Nesting of the black stork (Ciconia nigra) and white-tailed eagle (''Haliaeetus albicilla'') in relation to forest management''. Forest Ecology and Management, 185(3), 217–223. 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.


Behaviour

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.


Migration and dispersal

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 south of its nest near Karlstad, Sweden, another set of four color-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.Hagen,Y. (1976). ''Havørn og kongeørn i Norge''. Viltrapport, 1: 93 pg. 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 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 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, away to the southeast, or to
Gironde Gironde ( US usually, , ; oc, Gironda, ) is the largest department in the Nouvelle-Aquitaine region of Southwestern France. Named after the Gironde estuary, a major waterway, its prefecture is Bordeaux. In 2019, it had a population of 1,6 ...
,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, to the southwest.von Blotzheim, U. N. G., Bauer, K., & Bezzel, E. (1993). ''Handbuch der Vögel Mitteleuropas''. Akademische Verlagsgesellschaft. In several parts of Russia, quite unlike many European populations, the white-tailed eagle seems to be largely migratory. In the far east, the species appear to take different migratory routes in fall and spring, traveling from north-central Kamchatka thru the Kurile islands to Hokkaido in fall, while in spring these eagles travel north through
Sakhalin Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh ...
and the Okhotsk Coast. In the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
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 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 juvenile birds. Many such groups can contain up to 10 and, in areas near large breeding populations such as in Norway, at least 30–40 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 north of their natal site and northeast of their natal site.


Territoriality

Territory size in white-tailed eagles may vary from , usually less than , per one estimate. However, home ranges in northeastern Germany were much smaller than this, at . While territorial behavior 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.


Dietary biology

The white-tailed eagle's diet is varied, opportunistic and seasonal. Prey specimens can often include fish, birds and, mostly in a secondary capacity, mammals. White-tailed eagles are powerful predators and capable of attacking large prey of considerable sizes but, like most predators, prefer prey that is vulnerable and easy for them to capture.Valero, S.O.P. (2008). ''White-tailed Eagle hunting behaviour and food choice in Kvismaren''. Sveriges Ornitologiska Förening. Especially during the winter (and opportunistically in all seasons), many birds of the species live largely as scavengers, usually by coming across available carrion or watching for the activity of corvids,
vultures A vulture is a bird of prey that scavenges on carrion. There are 23 extant species of vulture (including Condors). Old World vultures include 16 living species native to Europe, Africa, and Asia; New World vultures are restricted to North and ...
or other raptors. White-tailed eagles in northeastern Germany were shown to hunt mostly from perches, in a "sit-and-wait" style, usually from a prominent tree perch. Like other sea eagles, they can only capture fish normally in the
littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal ...
, seldom hunting fish when they exceed a water depth of .Nadjafzadeh, M., Hofer, H., & Krone, O. (2016). ''Sit-and-wait for large prey: foraging strategy and prey choice of White-tailed Eagles''. Journal of Ornithology, 157(1), 165–178. In addition to trees, they may also use crags, hillocks or high grassy tussocks as hunting perches so long as the perch provides a good overall view of the environment. Fish tend to be grabbed in a shallow dive after a short distance flight from a perch, usually with the eagles only getting their feet wet. Occasionally, though, white-tailed eagles have been recorded plunging right into water, usually while hunting on the wing at a height of at least . In Norway, plunge-diving is considered rare. At times they will also fish by wading into shallows, often from shores or gravel islands. The species will at times variously follow
fishing boats A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing. The total number of fishing vessels in the world in 2016 was e ...
, readily exploits commercial
fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, ...
, stocked lakes, carp ponds and the like, and scavenges dead fish or fish-offal in a wide range of situations. When it comes to non-fish prey, it has been said that white-tailed eagles often hunt by flying low over
sea coast The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
or lakeshore and attempt to surprise victims. However, the hunting success rates on healthy birds can be low as revealed in studying wintering eagles in Sweden attempting to hunt
mallard The mallard () or wild duck (''Anas platyrhynchos'') is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa, and has been introduced to New Zealand, Australia, Peru, Brazil, Uruguay, Argen ...
s (''Anas platyrhynchos'').Rudebeck, G. (1950). ''The choice of prey and modes of hunting of predatory birds with special reference to their selective effect''. Oikos, 2(1), 65–88. White-tailed eagles also regularly
pirate Piracy is an act of robbery or criminal violence by ship or boat-borne attackers upon another ship or a coastal area, typically with the goal of stealing cargo and other valuable goods. Those who conduct acts of piracy are called pirates, v ...
food from
otter Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine, with diets based on fish and invertebrates. Lutrinae is a branch of the Mustelidae family, which also includes we ...
s and other birds including
cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...
s,
gull Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century ...
s,
osprey The osprey (''Pandion haliaetus''), , also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor reaching more than in length and across the wings. It is brown o ...
s, corvids and various other raptors.
Carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
is often the primary food source during lean winter months, with fish and
ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...
s preferred but everything from
cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel th ...
s to
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to ani ...
to even
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
s being eaten after death. From studies of captive white-tailed eagles, daily food requirements were estimated at , which is equivalent to about 10% of the birds' body weight, with crop contents commonly of .Uttendorfer, O. (1939). ''Die Ernahrung der deutschen Raubvogel und Eulen''. Neudamm. Verlag Neumann, 204–209. Some semi-captive juveniles on the isle of
Rùm Rùm (), a Scottish Gaelic name often anglicised to Rum (), is one of the Small Isles of the Inner Hebrides, in the district of Lochaber, Scotland. For much of the 20th century the name became Rhum, a spelling invented by the former owner, Sir ...
, Scotland could eat up to in one sitting. However, in Norway, it was estimated that a family of wild white-tailed eagles including each adult and three fledglings were consuming on average up to per bird each day. Furthermore, one male consumed an estimated in a single meal upon capturing a large fish. The crop can bulge to the size of a small
grapefruit The grapefruit (''Citrus'' × ''paradisi'') is a subtropical citrus tree known for its relatively large, sour to semi-sweet, somewhat bitter fruit. The interior flesh is segmented and varies in color from pale yellow to dark pink. Grapefruit ...
after they've consumed a large meal. Many studies have reflected that the primary foods of white-tailed eagles are fish and water birds. These are the primary food as well for other sea eagle species. However, unlike most ''Haliaeetus'', including the bald eagle and Steller's sea eagle, the water birds tend to take the primary position in the diet.Mlíkovský, J. (2009). ''The food of the white-tailed sea eagle (''Haliaeetus albicilla'') at Lake Baikal, East Siberia''. Slovak Raptor Journal, 3: 35–39. From 26 accumulated food studies for this species, prey remains and pellets show that about 48.5% of the diet is made up of birds, 39.95% by fish, 9.95% by mammals and 1.6% by other foods. In total, more than 300 prey species are known throughout the bird's range.Vrezec, A. (2016). ''Prehranska niša orla belorepca (''Haliaeetus albicilla'') z idejnim predlogom za izvedbo dodatnega krmljenja vrste v širši okolici Reškega jezera pri Kočevski reki''. Poročilo v okviru projekta LIFE Kočevsko (LIFE13 NAT/SI/000314), Ljubljana. However, based on studies of prey remains and pellets in laboratories from Greenland white-tailed eagles, birds were shown to be biased in both kinds of remains (pellets and prey remains) whereas in situ study and direct nest observation favor fish. Going on pellet/remains alone here in Greenland from 557 items in the 1979 study, 68% of the diet would’ve been represented by birds and only 20% by fish but comprehensive observation shifted it to show fish were the primary food at 58% and birds were secondary at 30%. This study claimed this is often because the bones of fish are dissolved by the large digestive tract of the eagles upon consumption and may thus leave almost nothing in remains and to some extent in pellets. Subsequent studies here showed a much stronger preference for fish in Greenland by 1983, as fish comprised an extreme 91.8% of 660 items.Wille, F., & Kampp, K. (1983). ''Food of the white‐tailed eagle ''Haliaeetus albicilla'' in Greenland''. Ecography, 6(1), 81–88.Kampp, K. and F. Wille. (1979). ''Fodevaner hos den Gronlandske Havorn ''Haliaeetus albicilla groenlandicus'' Brehm. (Food habits of the Greenland White-tailed Eagle).'' Dansk Ornithologisk Forenings Tidsskrift, 73: 157–64. (In Danish with English summary). However, this kind of direct continuous observation of food deliveries to nests is not always possible. Furthermore, despite similar bias for prey that is large and leaves conspicuous remains (including any larger fish, bird or mammal), in the bald eagle it was found that fish were usually detectable and dominant in remains and pellets. Most modern biologists may need to leave some fish unidentified but will account for different methodologies of prey study to get the most complete picture attainable. During winter, mammal prey can become more important in foods locally, as indicated in Scotland and shown in Norway and eastern Germany. As much as 41% of the diet can be made up of mammals, as was the case on the
Kola Peninsula The Kola Peninsula (russian: Кольский полуостров, Kolsky poluostrov; sjd, Куэлнэгк нёа̄ррк) is a peninsula in the extreme northwest of Russia, and one of the largest peninsulas of Europe. Constituting the bulk ...
. There is evidence of strong seasonal shifts in food habits in several parts of the range, usually the largest portions of fish are caught during warmer months while birds and mammals are more important in the colder months, especially in coastal areas such as Norway when preferred fish prey often move to deeper water during winter.Dornbusch, M. (1977). ''Der Seeadler ''Haliaeetus albicilla'' (L. 1758) in der Deutschen Demokratischen Republik''. In Report of WWF symposium of the White-tailed Eagle: 17–18. Among both fish and bird prey, it is thought that a majority that are caught weigh between . At times it has been said that "most" prey of white-tailed eagles will weigh only .Sulkava, S., Tornberg, R., & Koivusaari, J. (1997). ''Diet of the white-tailed eagle ''Haliaeetus albicilla'' in Finland''. Ornis Fennica, 74(2), 65–78. However, the mean prey sizes caught can show greater variability. Three studies showed that mean prey size varied from in the
Wigry National Park '' , iucn_category = II , photo =Poland Wigry Lake.jpg , photo_caption = Wigry Lake at sunset Park logo with Eurasian beaver , location = Podlaskie Voivodeship, Poland , nearest_city = Suwałki , map = Poland , relief = 1 , map_caption = L ...
, Poland, in the
Rybinsk Reservoir Rybinsk Reservoir ( rus, Ры́бинское водохрани́лище, r=Rybinskoye vodokhranilishche, p=ˈrɨbʲɪnskəɪ vədəxrɐˈnʲilʲɪɕə), informally called the Rybinsk Sea, is a water reservoir on the Volga River and its tributa ...
, Russia and in the Volga-Kama Nature Reserve, Russia.Zawadzka, D. (1999). ''Feeding habits of the black kite Milvus migrans, red kite Milvus milvus, white-tailed eagle ''Haliaeetus albicilla'' and lesser spotted eagle Aquila pomarina in Wigry National Park (NE Poland)''. Acta ornithologica, 34(1), 65–75. Thus, the mean prey size falls just slightly short of the mean prey mass of the golden eagle, which globally averages about .


Fish

Overall, nearly 70 species of fish are known to be taken from throughout the white-tailed eagle's range. White-tailed eagles can hunt fish in fresh or saltwater as well as those that prefer brackish water areas. However, they are basically restricted to taking fish in extremely shallow water, often by preference in water less than deep. Ideal fishing areas can be found in areas such as the Baltic Sea, where low coasts and archipelagos often have a relatively shallow water. While healthy, large fish are often taken as well, white-tailed eagles often take out sickly, injured or already dead fish. In some cases, the fish prey will float to the surface when infected by fish tapeworm, as is often the case with some fish families such as
carp Carp are various species of oily freshwater fish from the family Cyprinidae, a very large group of fish native to Europe and Asia. While carp is consumed in many parts of the world, they are generally considered an invasive species in parts of ...
. Fish are also caught after being battered, injured, and killed at power plants, from large-scale fishing nets, or are taken directly from human fishermen. Benthic fish tend to cling to rocks or sandy soil in shallows may be more vulnerable since they tend to look downward rather upward and are less competent at escaping predators coming from above the water's surface. Therefore, lurking benthic fish such as lumpsuckers are more vulnerable than many. Besides vulnerability, habitat, and prey behavior, fish body size may be a driver in the piscivore's dietary preferences. Studies have indicated that fish less than are taken infrequently, since they have a lower yield, fish of up to are taken secondarily and fish between are preferred since they have the highest nutritional benefit. Fish taken can exceed but since they can start to considerably exceed the weight of the eagle itself, they may prove too difficult to overpower. One large
Atlantic halibut The Atlantic halibut (''Hippoglossus hippoglossus'') is a flatfish of the family Pleuronectidae. They are demersal fish living on or near sand, gravel or clay bottoms at depths of between . The halibut is among the largest teleost (bony) fish in ...
(''Hippoglossus hippoglossus'') was found with the disembodied feet of a white-tailed eagle still embedded in its back, presumed the eagle drowned after being overpowered and drug under only to rot off, leaving only feet. Since they do not have the waterproofing oils on the plumage of the more accomplished raptorial diver, the osprey (''Pandion haliaetus''), white-tailed eagles prefer not to get their feathers wet as it can take a long time for them to dry. This may also make them vulnerable to losing their catch to other white-tailed eagles since their flight may be impaired until the wings are dried. Therefore, when hunting fish, they will almost always take flight as soon as possible to a feeding perch or nest. Another option when taking particularly large fish is for the eagle to stay in the water and row, swimming using their wings, across the water to the nearest bank or shore. While this would leave them waterlogged, of course, the food yield from such a catch is obviously attractive. White-tailed eagles have been photographed doing this with a large fish successfully in Greenland and 35 such cases were reported in Norway alone. The most frequently recorded prey species in 18 food studies from across the range is the
northern pike The northern pike (''Esox lucius'') is a species of carnivorous fish of the genus ''Esox'' (the pikes). They are typical of brackish water, brackish and fresh waters of the Northern Hemisphere (''i.e.'' holarctic in distribution). They are kno ...
(''Esox lucius''), present in at least 16 of those studies. Pike was found to be the main prey species in both the Baltic Sea and Lapland in Sweden, at three breeding locations in Finland, in two studies from Germany, and in
Belarus Belarus,, , ; alternatively and formerly known as Byelorussia (from Russian ). officially the Republic of Belarus,; rus, Республика Беларусь, Respublika Belarus. is a landlocked country in Eastern Europe. It is bordered by ...
. The maximum representation of pike known was in Lapland, where they comprised 38.2% of 809 food items.Fischer W. (1982). ''Die Seeadler'' . Die Neue Brehm-Bücherei , A. Ziemsen Verlag , WittenbergLutherstadt.Ekblad, C. (2004). ''Havsörnens häckningstida näringsval i olika skärgårdszoner på Åland''. Doktorsavhandling. Institutionen för Ekologi och Systematik. Avdelningen för populationsbiologi. Februari. The next most widely reported fish prey species is the common bream (''Abramis brama''). This bream was reported in 10 of 18 dietary studies and was the main prey in the Polesie State Radioecological Reserve, Belarus, in the
Ural mountains The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through western ...
region of Russia, and in the Kostomuksha Nature Reserve, Russia.Adrianova, O. V., & Kashevarov, B. N. (2005). ''Some Results of Long-Term Raptor Monitoring in the Kostomuksha Nature Reserve''. Status of Raptor Populations in Eastern Fennoscandia, Proceedings of the Workshop, Kostomuksha, Karelia, Russia.Yurko, V.V. (2016). ''Diet of the White-Tailed Eagle During the Breeding Season in the Polesski State Radiation-Ecological Reserve, Belarus''. Raptor Conservation, 32: 21–31.Samago, L. (1995). ''White-tailed eagle - ''Haliaeetus albicilla'' L.'' Propagation of the Urals and adjacent territories to poly-terrestrial sources: 107–122. Like the pike, the relatively large size of common bream, which weigh about on average, can prove attractive to hunting eagles. Many varieties of fish are taken opportunistically and randomly, as opposed to pike and bream, which can locally appear to be selected out of proportion to their regional population. Particularly diverse in the white-tailed eagle's prey spectrum are the family
Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest ve ...
, of which more than 20 species are known to be predated including the common bream. Others taken with some preference may include
salmonid Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefi ...
s and cod and their allies, both families known to obtain relatively large body sizes and occasional habituate shallow water, as well as lumpsuckers because they are benthic. In Greenland, the leading prey species is the salmonid, the
Arctic char The Arctic char or Arctic charr (''Salvelinus alpinus'') is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is Circumpolar North. It spawns Spawn is the eggs a ...
(''Salvelinus alpinus''), which comprised 27.2% of 660 prey items. The secondary prey in Greenland was recorded as two species of cod. While the Arctic char can average up to and cod can sometimes grow considerably larger than that, the average weight of cod taken here was estimated at only and the average char at . The largest cods and chars taken during the study were and respectively. In Norway, of 524 fish prey items, the common lumpsucker (''Cyclopterus lumpus''), which averages up to but is usually smaller, made up 24% of fish taken and the
Atlantic wolffish The Atlantic wolffish (''Anarhichas lupus''), also known as the seawolf, Atlantic catfish, ocean catfish, devil fish, wolf eel (the common name for its Pacific relative), woof or sea cat, is a marine fish of the wolffish family Anarhichadidae, n ...
(''Anarhichas lupus'') made up 17% of fish taken. However, fish were secondary to birds overall in Norway. Per two studies from Sweden, fish were usually the main food unlike in Norway and Finland, and could comprise 51–60% of the diet. Fish were also somewhat dominant in the foods from two studies in Belarus, making up 48.1–53.7% of the diet.Ivanovsky, V.V. (2010). ''White-tailed eagle ''Haliaeetus albicilla'' in the Byelorussian Poozerie: materials on the biology of the species within the range''. Russian Ornithological Journal, 19: 1876–1887. Fish similarly were important to nesting eagles in Hokkaido, Japan where 54% of 533 prey items were fish, led by the Alaska pollock (''Gadus chalcogrammus'') at 18.4%.Mori, S. (1980). ''Breeding biology of the White-tailed Eagle ''Haliaeetus albicilla'' in Hokkaido, Japan''. Japanese Journal of Ornithology, 29(2–3), 47–68. In different studies of the
Danube Delta The Danube Delta ( ro, Delta Dunării, ; uk, Дельта Дунаю, Deľta Dunaju, ) is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Ro ...
of Romania, from 44.6% to 79% of the diet was comprised by fish, led by the
common carp The Eurasian carp or European carp (''Cyprinus carpio''), widely known as the common carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Arkive The ...
(''Cyprinus carpio'') and Prussian carp (''Carassius gibelio'').Sandor, A. D., Alexe, V., Marinov, M., Dorosencu, A., Domsa, C., & Kiss, B. J. (2015). ''Nest-site selection, breeding success, and diet of white-tailed eagles (''Haliaeetus albicilla'') in the Danube Delta, Romania''. Turkish Journal of Zoology, 39(2), 300–307. In the Kostomuksha Nature Reserve of Russia, fish were strongly dominant in food remains, making 80% of the known diet.


Birds

White-tailed eagles are known to prey on about 170 species of bird, the most diverse group in their prey spectrum. While hunting birds, this massive, relatively slow-flying eagle requires an element of surprise, with often a tactful use of cover or bright sunlight upon the approach from a nearby perch. For example,
grey heron The grey heron (''Ardea cinerea'') is a long-legged wading bird of the heron family, Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in much of its range, but some populations from the more north ...
s (''Ardea cinerea'') have been caught after an eagle used a low flight over turbulent water to ambush them. However, even with a stealthy attack, the
waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which ...
favored in the avian diet tend to be highly wary and will more often than not escape. The white-tailed eagles must then attack birds at times of vulnerability or injury, or will often utilize the prey's escape tactics against them. Diving ducks and other diving water birds will be taken preferentially where they are available. In hunting diving birds, they utilize a technique of forcing the birds to dive repeatedly to avoid attacks, until the victim is exhausted from the efforts and can then be caught. Usually while hunting like this, the white-tailed eagle tends to circle low to stay close to the intended victim, with birds diving in shallower water being preferred. Ducks with conspicuous plumage, such as male common eiders (''Somateria mollissima''), with their pale plumage, may be easier to see under water and so may be taken somewhat more via this hunting method. Beyond waterfowl, both
loon Loons ( North American English) or divers ( British / Irish English) are a group of aquatic birds found in much of North America and northern Eurasia. All living species of loons are members of the genus ''Gavia'', family Gaviidae and order ...
s and
grebe Grebes () are aquatic diving birds in the order Podicipediformes . Grebes are widely distributed freshwater birds, with some species also found in marine habitats during migration and winter. Some flightless species exist as well, most notably ...
s have been seen to be successfully hunted in this way. Eagles were recorded doing up to 12 attacks on eiders in Russia and were usually successful in procuring prey. Even as many as 65 passes have recorded in less than 45 minutes but more than a few attacks also start to exhaust the eagle, as one immature gave up after 15–28 attempts at a little grebe (''Tachybaptus ruficollis''). While bald eagles may attack diving ducks in the same way, they appear to do so somewhat less regularly and successfully.Buehler, D. A. (2000). ''Bald Eagle (Haliaeetus leucocephalus) '', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. White-tailed eagles usually have less success hunting
dabbling duck The Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a yo ...
s because their normal predator response behavior is to take flight. In one instance, a mallard was caught while flying in mid-air, but usually the much larger eagle is unable to capture ducks in flight. While somewhat less swift in flight, healthy geese can usually outpace a heavier eagle as well and one
bean goose The bean goose (''Anser fabalis'' or ''Anser serrirostris'') is a goose that breeds in northern Europe and Eurosiberia. It has two distinct varieties, one inhabiting taiga habitats and one inhabiting tundra. These are recognised as separate s ...
(''Anser fabalis'') was even recorded to have defended itself successfully against an eagle's attack even though this goose was injured. White-tailed eagles often hunt dabbling ducks and geese most successfully when they are molted into their eclipse plumage which renders them temporarily flightless.
Swan Swans are birds of the family Anatidae within the genus ''Cygnus''. The swans' closest relatives include the geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Som ...
s during winter may find themselves forced to land due to their bulk on a sheet of ice over water if they can find no open water, which can make their feet stuck to the ice. White-tailed eagles have been recorded utilizing this disability to attack and kill swans.Fischer, W. (1970). ''Die Seeadler''. A. Ziemsen Verlag. They've also been seen to attack numerous waterfowl when the birds are injured by buckshot from duck hunters. Due to their status as enemy of other large birds, they are frequently
mobbed ''Mobbed'' is an American hidden camera reality television show based on the use of flash mobs as part of the spectacle for the delivery of an important personal message. The show, created by Howie Mandel, Darryl Trell, and Howard Kitrosser, ai ...
by them and white-tailed eagles have been recorded utilizing violent mobbings to suddenly turn over in flight and predaceously grab one of the birds mobbing them, including large gulls and even a
northern goshawk The northern goshawk (; ''Accipiter gentilis'') is a species of medium-large raptor in the family Accipitridae, a family which also includes other extant diurnal raptors, such as eagles, buzzards and harriers. As a species in the genus '' Acci ...
(''Accipiter gentilis'').Meinertzhagen, R. (1959). ''Pirates and Predators: The piratical and predatory habits of birds''. Oliver and Boyd. As an opportunistic predator, it often takes young birds freely as well as adult and fledged juvenile birds. In general, due to different nesting situations, white-tailed eagles instead of dabbling or diving water birds usually attack the more conspicuous or open nests of gulls, those of several other types of
seabird Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same envir ...
, large corvids or other accipitrids. In Germany and Scotland, up to 86% of gulls taken were nestlings and juveniles. Cases of white-tailed eagles eating eggs, instead of nestlings or older birds, is considered rare. Nonetheless, they have been recorded eating a few eggs, which they may carry in their beaks rather in their feet, of some seabirds such as kittiwakes, eiders, cormorants and gulls. The most widely recorded avian prey species and, second most widely recorded prey species behind the pike, is the mallard, due to its circumpolar range and commonality in many wetlands areas. However, as aforementioned, healthy mallards are difficult for white-tailed eagles due to their tendency to fly at first sign of danger. However, exploiting the mallard's flightlessness during eclipse plumage may result in eagles hunting them intensely only in late summer. Due to this mallards are usually a secondary prey species year around. The largest known representation of mallards in the diet were from
Müritz National Park The Müritz National Park (german: Müritz-Nationalpark) is a national park situated roughly in the middle between Berlin and Rostock, in the south of the German state of Mecklenburg-Vorpommern. It extends over large portions of the Müritz ...
in Germany, where mallards were the third best represented prey species at 10.1% of 247 items and from
Augustów Primeval Forest Augustów Primeval Forest or Augustów Forest ( pl, Puszcza Augustowska, lt, Augustavo giria, be, Аўгустоўская пушча) is a large virgin forest complex located in Poland, as well as in northern Belarus and southeastern Lith ...
in Poland, where mallards were the second most numerous prey and made up 9.84% of 803 items. Taken more preferentially where they occur are common eiders. When hunting eiders, perhaps the largest of diving ducks at a mean weight of , white-tailed eagles frequently force the eider to dive repeatedly until it is exhausted and can be captured. When sitting on the nest, the female common eider will try to escape in flight but is a relatively weak and ponderous flier and so too may be often victimized by the eagles. Otherwise the pale plumage of adult male common eiders while they're diving is reported to make them more vulnerable to eagle attacks. Eiders were the leading prey species in Norway making 18.8% of 1612 prey items, as well as in
Åland Åland ( fi, Ahvenanmaa: ; ; ) is an autonomous and demilitarised region of Finland since 1920 by a decision of the League of Nations. It is the smallest region of Finland by area and population, with a size of 1,580 km2, and a populat ...
, Finland where the eider comprised 18.63% of 5161 prey items (thus nearly a thousand eiders were taken here). Eiders also appeared to be the main prey species in Iceland.Ingólfsson, A. 1961. ''The distribution and breeding ecology of the White-tailed Eagle ''Haliaeetus albicilla'' (L.) in Iceland''. B.Sc. (Hons.) thesis. University of Aberdeen. There is evidence that a growing white-tailed eagle population is having a net negative effect on eider numbers in some areas, and locally eiders have altered to partial nocturnal foraging apparently to avoid hunting eagles.Hipfner, M. J., Blight, L. K., Lowe, R. W., Wilhelm, S. I., Robertson, G. J., Barrett, R., Anker-Nilssen, T. & Good, T. P. (2012). ''Unintended consequences: how the recovery of sea eagle Haliaeetus spp. populations in the northern hemisphere is affecting seabirds''. Recovery of Sea Eagles in the northern hemisphere. Marine Ornithology 40: 39–52. In inland regions, an avian prey species preferred by white-tailed eagles is the Eurasian coot (''Fulica atra''). The coot is the second most widely represented bird prey species (and fourth species of any class known overall) in 18 dietary studies. Coots bunch together in marshy spots when approached by a flying eagle and as many as five eagles at once have been recorded attacking large flocks on the water. Coots behaviour often endangers them to large raptors: they seldom dive, are weaker and slower fliers than most water birds and are collectively often less wary and more approachable than most waterfowl are. Coot were strongly the dominant food in Wigry National Park, Poland where they made up 44.1% of 299 items, and were also the leading prey in Augustów Primeval Forest (Poland) where they made up 11.59% of the foods. Overall at Wigry and Augustów, birds altogether made up 66.2% and 47.83% of the diets, respectively. In the Danube Delta, Romania, birds climbed in importance of the diet from 21% in 1970 to 50% by 2015, thanks largely to increased numbers of coots. In total, about 38 species of waterfowl are known to be hunted, as well as all available species of loons and grebes, several types of rails, tubenoses as well as
heron The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychu ...
s,
stork Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family called Ciconiidae, and make up the order Ciconiiformes . Ciconiiformes previously included a number of other families, such as herons an ...
s and other assorted large waders. White-tailed eagles also are known to hunt some 42 species of
shorebird 245px, A flock of Dunlins and Red knots">Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflat ...
, most significantly gulls and
alcid An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word "auk" is derived from Icelandic ''álka'', from Old Norse ''alka'' (a ...
s. Even shorebirds as small as little stint (''Calidris minuta''),
wood sandpiper The wood sandpiper (''Tringa glareola'') is a small wader. This Eurasian species is the smallest of the shanks, which are mid-sized long-legged waders of the family Scolopacidae. The genus name ''Tringa'' is the New Latin name given to the green ...
(''Tringa glareola'') and common ringed plover (''Charadrius hiaticula'') are known to be preyed upon, albeit quite rarely. More than a dozen gulls are known in the prey spectrum from the smallest to all four largest extant species. In the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
,
northern fulmar The northern fulmar (''Fulmarus glacialis''), fulmar, or Arctic fulmar is a highly abundant seabird found primarily in subarctic regions of the North Atlantic and North Pacific oceans. There has been one confirmed sighting in the Southern Hem ...
(''Fulmarus glacialis'') are noted as a common prey species and as such may contribute to locally high levels of DDT and PCB chemicals in nesting eagles. However, fulmars defend themselves by regurgitating a smelly, tar-like oily substance that can impair the flight of predators and may even kill some intended predators when it is in large quantity, and young juvenile eagles, being less cautious and experienced, are most prone to being severely "oiled". Alcids such as murres tend to become especially important in the diet of eagles in coastal Norway during winter, especially near offshore islands, when coastal fish tend to move to deeper waters. At least eight species of dabbling duck are known in the prey spectrum. Due to the social inclination of dabbling ducks, they perhaps have the most success hunting isolated birds but they've also been taken from panic-stricken flocks as well. Despite the difficulty of taking them, dabbling ducks of unidentified species were found to be the main food of white-tailed eagles in
Lake Baikal Lake Baikal (, russian: Oзеро Байкал, Ozero Baykal ); mn, Байгал нуур, Baigal nuur) is a rift lake in Russia. It is situated in southern Siberia, between the federal subjects of Irkutsk Oblast to the northwest and the ...
, where they comprised 51.8% of 199 prey items.Mlíkovský, J. (1992). ''Population status and food of the White-tailed Fish Eagle ''Haliaeetus albicilla'' (Aves: Accipitridae) in the Svjatoj Nos wetlands, Lake Baikal''. MLÍKOVSKÝ, J. & STÝBLO, P.(Eds.): Ecology of the Svjatoj Nos wetlands, Lake Baikal.-Ninox Press, Praha: 79, 88. In
Fennoscandia __NOTOC__ Fennoscandia ( Finnish, Swedish and no, Fennoskandia, nocat=1; russian: Фенноскандия, Fennoskandiya) or the Fennoscandian Peninsula is the geographical peninsula in Europe, which includes the Scandinavian and Kola penin ...
, they are attracted to coastal waters during winter to attack large numbers of diving ducks including eiders, common goldeneye (''Bucephala clangula''),
common Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common, a central public park in Boston, Massachusetts * Cambridge Common, common land area in Cambridge, Massachusetts * Clapham Common, originally ...
(''Mergus merganser'') and red-breasted mergansers (''Mergus serrator''), tufted ducks (''Aythya fuligula'') and
scoter The scoters are stocky seaducks in the genus ''Melanitta''. The drakes are mostly black and have swollen bills, the females are brown. They breed in the far north of Europe, Asia, and North America, and winter farther south in temperate zone ...
s. Year around in
Åland Åland ( fi, Ahvenanmaa: ; ; ) is an autonomous and demilitarised region of Finland since 1920 by a decision of the League of Nations. It is the smallest region of Finland by area and population, with a size of 1,580 km2, and a populat ...
, 66.2% of 5161 food items were birds, while in the three sites in different parts of Finland birds made up 51.1% of 3152 food items. In Germany, 52.4% of 1637 prey items were birds, mostly coots and unidentified waterfowl. More locally in Germany, in Müritz National Park the percentage of birds in the diet climbs to 65.73% Birds were strongly dominant in food records from Scotland, making up 73.53% of 1930 prey items, and in Kandalaksha Nature Reserve, where they comprised 75% of 523 prey items. While most of the aforementioned water birds are modest of size and taken largely due to ease (diving water birds, whether healthy or infirm, and usually infirm or molting dabbling water birds), white-tailed eagles routinely attack larger water birds as well. In many areas, large numbers of graylag geese (''Anser anser''), Europe's largest native wild goose, are taken. For example, they were the main prey, making up 28.2% of 192 prey items, for wintering eagles in Oostvaardersplassen, Netherlands, and the second most often recorded prey species in both Müritz National Park (Germany), where they made up 16.42% of 247 prey items, and in Austria, where they made up 9.5% of 349 items.Probst, R. (2009). ''Der Seeadler (''Haliaeetus albicilla'') in Österreich'': Das WWF Österreich Seeadlerprojekt. Denisia, 27, 29–50. White-tailed eagles are known to prey on at least 10 species of geese, ranging in size from the
red-breasted goose The red-breasted goose (''Branta ruficollis'') is a brightly marked species of goose in the genus ''Branta'' from Eurasia. It is currently classified as vulnerable by the IUCN. Taxonomy and etymology The red-breasted goose is sometimes placed ...
(''Branta ruficollis'') to the non-native
Canada goose The Canada goose (''Branta canadensis''), or Canadian goose, is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is ...
(''Branta canadensis''). They will take many goslings during summer, as greylag goslings alone can comprise up 23% of the seasonal bird prey, and fully-grown geese in other seasons. Large waders are taken when possible, including a half dozen
heron The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychu ...
species, and, larger still, both the young and adults of common cranes (''Grus grus'') and both the
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ha ...
and the
white stork The white stork (''Ciconia ciconia'') is a large bird in the stork family, Ciconiidae. Its plumage is mainly white, with black on the bird's wings. Adults have long red legs and long pointed red beaks, and measure on average from beak tip to e ...
(''Ciconia ciconia''). Black and white storks are primary prey species in the Polesie State Radioecological Reserve, Belarus, where they comprised 12.6% (second most regular prey species) and 6.3% (fourth most regular) of the diet, respectively. Large numbers of black stork were also taken in Augustów Primeval Forest where nearly 50 were found around eagle nests. They are reported to have attacked and eaten the largest seabirds they encounter, such as
great cormorant The great cormorant (''Phalacrocorax carbo''), known as the black shag in New Zealand and formerly also known as the great black cormorant across the Northern Hemisphere, the black cormorant in Australia, and the large cormorant in India, is a w ...
s (''Phalacrocorax carbo'') and in some cases, such as in the Baltic Sea, have nearly destroyed whole colonies, from the eggs to the adults which average about . In the
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
n island of Hiiumaa, home to at least 25 pairs of sea eagles, as many as 26 individuals have been observed simultaneously culling a single cormorant colony. Similarly large numbers were taken of the Japanese cormorant (''Phalacrocorax capillatus''), which was the second most numerous prey species, making up 11.63% of 533 prey items in Hokkaido, and opportunistically, when their
north Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe a ...
colonies are accessed, great numbers of
northern gannet The northern gannet (''Morus bassanus'') is a seabird, the largest species of the gannet family, Sulidae. It is native to the coasts of the Atlantic Ocean, breeding in Western Europe and Northeastern North America. It is the largest seabird in t ...
s (''Morus bassanus'').Whitfield, D. P., Marquiss, M., Reid, R., Grant, J., Tingay, R., & Evans, R. J. (2013). ''Breeding season diets of sympatric White-tailed Eagles and Golden Eagles in Scotland: no evidence for competitive effects''. Bird study, 60(1), 67–76. Vagrant white-tailed eagles in
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
were recorded to prey on several Laysan albatross (''Phoebastria immutabilis'') and were suspected to prey on black-footed albatross (''Phoebastria nigripes''), both weighing about . Another large water bird taken as adults are
common loon The common loon or great northern diver (''Gavia immer'') is a large member of the loon, or diver, family of birds. Breeding adults have a plumage that includes a broad black head and neck with a greenish, purplish, or bluish sheen, blackish ...
s (''Gavia immer''). However, the largest water birds they are known to kill are adult swans, including
mute Muteness is a speech disorder in which a person lacks the ability to speak. Mute or the Mute may also refer to: Arts and entertainment Film and television * ''Mute'' (2005 film), a short film by Melissa Joan Hart * ''Mute'' (2018 film), a scien ...
(''Cygnus olor''), whooper (''Cygnus cygnus'') and Bewick's swans (''Cygnus columbianus bewickii''). While cygnets and disabled birds (either by natural conditions such as ice or by human hunters) are at the greatest risk for eagle predation, white-tailed eagles have prey upon even healthy adult swans weighing at least . While land birds are a more infrequently part of the diet, at least 60 species have been recorded in the white-tailed eagles prey spectrum. For the most part, land birds are taken so infrequently as to not warrant much mention. However, variable numbers of gamebirds are taken opportunistically, and in Belarus and Russia, especially around the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
where ptarmigan are not infrequent prey, they will take a few grouse. White-tailed eagles are known to prey on some numbers of ring-necked pheasant (''Phasianus colchicus'') in Austria. They will at times attack adult male western capercaillie (''Tetrao urogallus''), of note for their large size at . However, this is dwarfed by the largest avian prey credited to a white-tailed eagle, an adult male great bustard (''Otis tarda''), which weighed an estimated (which, much like exceptionally large fish taken, must have been consumed in the killing spot or subsequently dismantled as too large to fly with). Among the land birds taken, more than 20
passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
s are included in the prey spectrum but most are obviously too small and swift to be anything but incidental prey. The smallest avian prey known for white-tailed eagles was a great tit (''Parus major''), a species which weighs on average. On one hand, small bird prey may be under-recorded since they leave few conspicuous remains but, on the other, are unlikely worthy of much pursuit as they have little food value. However, in one case, a white-tailed eagle was seen to fly into a
murmuration Starlings are small to medium-sized passerine birds in the family Sturnidae. The Sturnidae are named for the genus ''Sturnus'', which in turn comes from the Latin word for starling, ''sturnus''. Many Asian species, particularly the larger ones, ...
of Eurasian starlings (''Sturnus vulgaris'') and come away with a starling in hand. The only passerine family taken in numbers would be the larger corvids, of which eight species are known in the prey spectrum. In Hokkaido, Japan, two species of corvid were well-represented in the diet, the
large-billed crow The large-billed crow (''Corvus macrorhynchos''), formerly referred to widely as the jungle crow, is a widespread Asian species of crow. It is very adaptable and is able to survive on a wide range of food sources, making it capable of colonizing ...
(''Corvus macrorhynchos'') and the carrion crow (''Corvus corone''), which together comprised 14.8% of 533 prey items.


Mammals and other prey

Mammals are usually a quite secondary component of the diet. Although usually better represented than other non-fish and birds prey, their regional importance is variable. In known dietary studies, the mammalian contribution can vary from 0.49% to 41% of prey by number. When mammals are most significant to the diet, it usually due to local white-tailed eagles preying on rabbits and hares with some regularity. In some studies from Scotland, the European rabbit (''Oryctolagus cuniculus'') and
mountain hare The mountain hare (''Lepus timidus''), also known as blue hare, tundra hare, variable hare, white hare, snow hare, alpine hare, and Irish hare, is a Palearctic hare that is largely adapted to polar and mountainous habitats. Evolution The mount ...
(''Lepus timidus'') were found to contribute as much as nearly 25% of the diet. A similar contribution of European hares (''Lepus europaeus'') was found in the diet of Austria, where hares were the leading prey species making up 24.35% of 349 prey items (with mammals making up 34.67% of the overall diet). In studies from Germany, European hares were taken fairly often but were numerically secondary prey. Given that these rabbits and hares have average mature weights from in rabbits to in European and Arctic hares (''Lepus arcticus''), they can make a hearty contribution to the prey biomass when available (although certainly juveniles are attacked as much if not more so than adult rabbits and hares). The most widely reported mammalian prey known usually as a supplemental prey species are
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...
s, especially the non-native
muskrat The muskrat (''Ondatra zibethicus'') is a medium-sized semiaquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over a wide range of climates and habita ...
(''Ondatra zibethicus''), which averages about , and may be taken from "muskrat farms" or feral wetland populations. While largely a supplemental prey item, a respectable number of 137 were recorded in the diet from Finland. Also, a study on the Ili delta in Kazakhstan has shown up to 30–43% of prey remains at eyries to consist of muskrat in spring and fall but only 14% in summer (for unknown reasons). In total, about 20
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...
species are known in the white-tailed eagle's prey spectrum. In some of the coldest climes of Russia, such as in the Ural mountains or the Kola peninsula, white-tailed eagles have been recorded to live on surprisingly high numbers of small rodents, comprising 13.8% and more than 21% of all prey remains, respectively. Even agile
red squirrel The red squirrel (''Sciurus vulgaris'') is a species of tree squirrel in the genus ''Sciurus'' common throughout Europe and Asia. The red squirrel is an arboreal, primarily herbivorous rodent. In Great Britain, Ireland, and in Italy numbe ...
s (''Sciurus vulgaris'') may be caught from trees in some cases. The smallest rodents known in the prey spectrum are the common vole (Microtus arvalis) and the wood mouse (''Apodemus sylvaticus'') but mammalian prey down to the size of
common shrew The common shrew (''Sorex araneus''), also known as the Eurasian shrew, is the most common shrew, and one of the most common mammals, throughout Northern Europe, including Great Britain, but excluding Ireland. It is long and weighs , and has v ...
s (''Sorex araneus''), indeed the smallest vertebrate known to have been preyed upon, has been recorded. By contrast, kits of larger rodents such as
Eurasian Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipela ...
(''Castor fiber'') and North American beavers (''Castor canadensis'') (introduced) have been found as prey. Other mammals are also taken, usually canids and
mustelid The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in t ...
. At least seven species of
mustelid The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in t ...
have been recorded in the white-tailed eagle's diet, from the smallest weasel to polecats,
marten A marten is a weasel-like mammal in the genus ''Martes'' within the subfamily Guloninae, in the family Mustelidae. They have bushy tails and large paws with partially retractile claws. The fur varies from yellowish to dark brown, depending on ...
s,
sable The sable (''Martes zibellina'') is a species of marten, a small omnivorous mammal primarily inhabiting the forest environments of Russia, from the Ural Mountains throughout Siberia, and northern Mongolia. Its habitat also borders eastern Kaza ...
s, and rarely, even adult European otters (''Lutra lutra'').Arkadevich, M.V., Yuryevna, P.Y., Vladimirovich, T.A. & Valerevna, M.J. (2014). ''Nesting of the White-tailed Eagle (''Haliaeetus albicilla'') and the Long-legged Buzzard (''Buteo rufinus'') in the Rostovsky Reserve''. News of higher educational institutions. North-Caucasian region. Natural Sciences.Sidorovich, Vadim. Analysis of vertebrate predator-prey community: Studies within the European Forest zone in terrains with transitional mixed forest in Belarus. Tesey, 2011.NOVIKOV, G. A. 1956. Carnivorous mammals of the fauna of the U.S.S.R., 283 pp. (The Israel Program for Scientific Translations, Jerusalem, 1962) Another mustelid, the American mink (''Neogale vison'') was introduced as a furbearer to Finland but then became an invasive pest, as a fast-breeding killer that threatens many native species. In turn, Finnish white-tailed eagles have become the main natural control and may inhibit the mink from breeding via heavy predation. Conversely, the white-tailed eagle has not been known to prey on the critically endangered, native European mink (''Mustela lutreola'') (perhaps due to its shier habits) which the American mink are known to have been outcompeting in some areas (but the European has mainly declined due to massive overhunting by humans as a furbearer). Among canids, pups of Arctic foxes (''Vulpes lagopus'') being the sixth most regular prey species in
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
. Several
red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the Order (biology), order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe ...
es (''Vulpes vulpes'') was taken or scavenged in
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...
and
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bot ...
, and successful predatory attacks on red fox have been reported in
Belarus Belarus,, , ; alternatively and formerly known as Byelorussia (from Russian ). officially the Republic of Belarus,; rus, Республика Беларусь, Respublika Belarus. is a landlocked country in Eastern Europe. It is bordered by ...
. White-tailed eagles are often considered potential predators of raccoon dogs, and several predation has been reported in
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
and
Belarus Belarus,, , ; alternatively and formerly known as Byelorussia (from Russian ). officially the Republic of Belarus,; rus, Республика Беларусь, Respublika Belarus. is a landlocked country in Eastern Europe. It is bordered by ...
. Additionally, a white-tailed eagle was once observed to kill and feed on a live adult golden jackal (''Canis aureus'') that was trapped in a furbearer's trap.Bannerman, D. A. (1959). ''The birds of the British Isles (Vol. 8)''. Oliver and Boyd. White-tailed eagles are known to prey on seal pups but most are likely sickly and perhaps both adult and pup seals are most likely to be eaten as carrion. Four
Baikal seal The Baikal seal, Lake Baikal seal or (''Pusa sibirica''), is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true se ...
(''Pusa sibirica'') pups were taken in Lake Baikal. They are considered a predator even for live
grey seal The grey seal (''Halichoerus grypus'') is found on both shores of the North Atlantic Ocean. In Latin Halichoerus grypus means "hook-nosed sea pig". It is a large seal of the family Phocidae, which are commonly referred to as "true seals" o ...
(''Halichoerus grypus'') pups that weigh at birth. In one instance, a white-tailed eagle reportedly tried to attack an adult
harbor seal The harbor (or harbour) seal (''Phoca vitulina''), also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared se ...
(''Phoca vitulina'') but was immediately dragged into the water and soon surfaced dying with a broken wing. Similarly, in one anecdote, an eagle drowned while apparently attacking an adult
harbor porpoise The harbour porpoise (''Phocoena phocoena'') is one of eight extant species of porpoise. It is one of the smallest species of cetacean. As its name implies, it stays close to coastal areas or river estuaries, and as such, is the most familiar ...
(''Phocoena phocoena''). More than a dozen ungulate species have been found in the foods of white-tailed eagles, but a very large proportion of this is likely from carrion found already dead. Very large food sources such as
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s (''Equus ferus caballus''),
moose The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult ma ...
(''Alces alces''),
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...
(''Bos taurus'') and European bison (''Bison bosanus'') are certainly visited as carrion always. Wild ungulate species known to have their young attacked by white-tailed eagles in variable numbers may include deer such as
reindeer Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subs ...
(''Rangifer tarandus''),
red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of ...
(''Cervus elaphus'') and
European roe deer The roe deer (''Capreolus capreolus''), also known as the roe, western roe deer, or European roe, is a species of deer. The male of the species is sometimes referred to as a roebuck. The roe is a small deer, reddish and grey-brown, and well-adapt ...
(''Capreolus capreolus'') and
wild boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species i ...
(''Sus scrofa''). Boar made up 7.1% of the prey remains at Polesski Reserve, Belarus. At least two successful attacks on adult roe deer have been reported, which could potentially weigh around (their average mature weight), in addition to several cases of predation on young roe deer. A yearling juvenile male eagle scaling , newly reintroduced into the wild on the isle of Rùm killed a healthy, red deer calf within a couple of days. One of the primary causes of the white-tailed eagles persecution by humans is that white-tailed eagles often feed on domestic sheep (''Ovis aries'') and goats (''Capra aegagrus hircus''), especially lambs and kids. However, they do not necessarily take healthy specimens and often feed on them after death, instead. Of 36 cases of feeding on lambs and kids by white-tailed eagles in Norway, only 12 could be proven to have been taken alive by the eagles. Prey of other animal classes is rarely taken by white-tailed eagles. Particularly, the diversity of
reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s known in the prey spectrum, at only six species, is quite paltry when compared to the many species known to be hunted by the bald eagle. Further among
amphibian Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s only two species of toad are known to be taken. The Ural mountains is the only region where some diversity of reptile and amphibian species have been reported in their diet. In only the white-tailed eagles nesting in Hokkaido, they've been known to hunt large
cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
s such as robust clubhook squid (''Onykia robusta'') and giant Pacific octopus (''Enteroctopus dofleini''), though likely mainly younger specimens and those collected and perhaps injured by large-scale fishing operations. White-tailed eagle juveniles have been seen rarely foraging for unidentified clams and
mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which ...
s on the
Rhine ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , source ...
. However, the miscellaneous shells of marine mussels and snails found in Norway are probably usually consumed secondarily from the stomachs of eiders. An exceptional number of
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s, amounting to 24% of food items by number, were found in the foods of white-tailed eagles in Augustów Primeval Forest, almost entirely Odonata. The source of this food is not clear as the white-tailed eagle is far too large and bulky a raptor to invest much time in pursuit of insects.


Interspecies predatory relationships

As the largest eagle in the majority of its distribution, the white-tailed eagle is an apex predator in its range.Salo, P., Nordström, M., Thomson, R. L., & Korpimäki, E. (2008). ''Risk induced by a native top predator reduces alien mink movements''. Journal of Animal Ecology, 77(6), 1092–1098. In some areas it may compete with other large raptors, especially
golden eagle The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known bird ...
s. Relations between these two species are complex and variable. In Scotland, where both eagles have been reintroduced or re-established, competition is considerable. This is, in part, due to their diets being more similar here than elsewhere in their range, with both species preying heavily on rabbits and hares and being reliant on carrion all year round, whereas in most other areas both favor carrion mostly only in winter. As much as 90% of their diets in Scotland can overlap. The white-tailed eagle elsewhere usually prefers fish and water birds. Another factor is the reintroduction of white-tailed eagles occurred after golden eagles had been re-established in Scotland and that some of the golden eagles began to nest beyond their usually rocky, mountainous habitats, in or near trees in coastal or near lowland wet areas historically occupied by white-tailed eagles. More territorial conflicts between the species have been recorded in the last few decades. Given appropriate healthy populations and ample habitat, as in Norway, the golden and white-tailed eagles are considerably segregated in nesting regions and direct competition is much milder. In spite of a size advantage for the white-tailed eagle, the golden eagle is reportedly "strongly dominant" over the white-tailed in food conflicts and, perhaps, in direct nesting competition. This is in part because of the swifter, more agile flight of golden eagles, as well as their greater overall aggression towards other raptors and perhaps due to their somewhat longer toes and larger talons, although there is little evidence that the golden and white-tailed eagles are notably different in strength. In many intraguild diurnal raptor assemblages, a slightly smaller, swifter-flying species often dominate their heavier competitors unless size differences become extreme, to the contrary of owls and several other predators which often adhere fairly strictly to a size-based dominance hierarchy.Voous, K.H. 1988. ''Owls of the Northern Hemisphere''. The MIT Press, 0262220350. Golden eagles won all food conflicts over carrion observed by one author over the course of two winters in Norway, with the white-tailed eagles only displacing goldens after the golden eagles had already fed for some time. However, cases of white-tailed eagles winning food conflicts have been reported as well and perhaps more assured mature white-tailed eagles may fare better in such conflicts. Some territorial conflicts in Scotland have escalated, albeit rarely, to both eagle species killing the other. White-tailed eagles are said to be "dominant", however, in population ecology as they can exist at higher population densities and typically outnumber golden eagles because of their longer gut and more efficient digestive system, being able to live better with less food. Notably, in competition in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
, neither the golden or bald eagle are said to be dominant and either species may win conflicts. Furthermore, bald eagles may succeed in procuring up to 25% of fresh golden eagle kills in winter and golden eagles are reported to decidedly avoid active nesting areas of bald eagles. Beyond golden eagles, white-tailed eagles may live alongside a wide range of other large raptors, but other eagles are considerably different in dietary and habitat preferences, so there is almost no competitive effect. For example, in Kazakhstan, white-tailed eagles were recorded to nest in proximity to golden eagles, eastern imperial eagles (''Aquila heliaca'') and steppe eagles (''Aquila nipalensis'') and all four eagles appear almost entirely indifferent to the presence of the other species, given their considerable partitioning in diet and habitat preferences. More significantly than the ''Aquila'' species, the white-tailed eagle seemed to have no issue nesting within a few hundred metres of the other eagles. A more direct effect may be detected on other fish-eating birds, for example recovering numbers of white-tailed eagles in
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
was thought to limit local osprey populations. However, in similar habitats, white storks and lesser spotted eagles (''Clanga pomarina'') appeared to not be competitively effected.Treinys, R., Dementavičius, D., Mozgeris, G., Skuja, S., Rumbutis, S., & Stončius, D. (2011). ''Coexistence of protected avian predators: does a recovering population of White-tailed Eagle threaten to exclude other avian predators?'' European journal of wildlife research, 57(6), 1165–1174. Besides competitive effects, white-tailed eagles may adversely effect ospreys by habitually robbing them of their catches. Besides the poorly studied relations between the Pallas's fish eagle and white-tailed eagle in the southern limits of the latter's Asian distribution, the only other ''Haliaeetus'' to live broadly alongside white-tailed eagles are Steller's sea eagles. Being larger and heavier, the Steller's is often characterized as a more powerful predator. Nonetheless, studies of the species ecologies show that the Steller's is a more restricted feeder on salmonids and that the Steller's tended to defend a smaller home range area than white-tailed eagles do in the Russian Far East. However, the Steller's appeared to be more flexible in readily switching nest sites between trees and rocky areas, whereas white-tailed eagles of this area exclusively nested in trees. Both species seemed to avoid active territories of the other but little direct conflict during breeding was detected. Although the Steller's sea eagle may be somewhat favored in wintertime food conflicts given its sometimes considerably larger size, both it and the white-tailed eagles have been observed to win conflicts over fish, with golden eagles sometimes entering the fray and sometimes losing or winning conflicts. Given their larger population and farther current range into warmer areas (whereas the modern white-tailed eagle is only common in cold, northern climes), bald eagles (the ecological equivalent of the white-tailed eagle in North America) have a considerably broader prey spectrum than white-tailed eagles that ranges well over 400 species, with more species recorded from nearly all animal taxon. Although about 56% of the bald eagle's diet is comprised by fish, bald eagles often take a higher diversity and numbers of alternate prey such as mammals, reptiles and amphibians than do white-tailed eagles.Stalmaster, M.V. (1987). ''The Bald Eagle''. Universe Books, New York. 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 The common buzzard (''Buteo buteo'') is a medium-to-large bird of prey which has a large range. A member of the genus '' Buteo'', it is a member of the family Accipitridae. The species lives in most of Europe and extends its breeding range acr ...
(''Buteo buteo''),
northern goshawk The northern goshawk (; ''Accipiter gentilis'') is a species of medium-large raptor in the family Accipitridae, a family which also includes other extant diurnal raptors, such as eagles, buzzards and harriers. As a species in the genus '' Acci ...
, red kite (''Milvus milvus''),Palmer, R. S. (Ed.). (1988). ''Handbook of North American Birds Volume VI: Diurnal Raptors (Part 1)''. Yale University Press. 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 The Eurasian pygmy owl (''Glaucidium passerinum'') is the smallest owl in Europe. It is a dark reddish to greyish-brown, with spotted sides and half of a white ring around the back of the neck. This species is found in the boreal forests of North ...
(''Glaucidium passerinum''), boreal owl (''Aegolius funereus''), Eurasian hobby (''Falco subbuteo''), long-eared owl (Asio otus), northern hawk owl (''Surnia ulula''),
short-eared owl The short-eared owl (''Asio flammeus'') is a widespread grassland species in the family Strigidae. Owls belonging to genus ''Asio'' are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or ...
(''Asio flammeus''),
peregrine falcon The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a cosmopolitan bird of prey (raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey bac ...
(''Falco peregrinus''), snowy owl (''Bubo scandiacus'') and
Eurasian eagle owl The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl that resides in much of Eurasia. It is also called the Uhu and it is occasionally abbreviated to just the eagle-owl in Europe. It is one of the largest species of owl, and female ...
(''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.


Breeding


Courtship and mating

The breeding season is from January to July in the south of the white-tailed eagles range, and from April to September in the northern part of their range. They pair for life, though if one dies replacement can occur quickly. A bond is formed when a permanent home range is chosen. White-tailed eagles frequently engage during early spring variously in soaring, sky-dancing and other aerial displays, all with much loud calling, often performed by pair members together, including spectacular mutual cartwheel downwards where talons touch or interlock.Helander, B. (1985). ''Reproduction of the white‐tailed sea eagle ''Haliaeetus albicilla'' in Sweden''. Ecography, 8(3), 211–227. Nuptial displays may occur almost year-around in some parts of the range, increasing after young disperse in autumn, thence at rare intervals until spring when such behavior, of course, peaks. Courtship often begins with a bird, often the male, "sky pointing" or "long calling" by throwing their head back. Soaring by pairs follows, with either partner leading by or soaring opposite directions. One may swoop upon the other who responds by tilting to one side or may roll over to touch talons momentarily before separating. This may be repeated or gain intensity until they are talon-grappling or "mutual cartwheeling", consisting of the pair locking talons mid-air and whirling earthwards in series of spectacular cartwheels. When doing this, the pair may stop only a few feet above the ground. Talon grappling is usually associated with territorial clashes in most accipitrids, especially between males, but in ''Haliaeetus'' such behaviour also seems to be related to courtship and is engaged by pairs as well as males attacking intruding males. When locally common, 2–3 pairs can be seen displaying in the sky quite near each other but each pair in fact are within a border of a well-defined territory. In Greenland, recorded pair densities were 0.3–0.6 occupied territories per . In eastern Germany, densities were reported as 1.6–2 pairs per . Norwegian nests appear at no closer than ; territory size on Norwegian coasts were reported as roughly . Fischer noted 8–9 pairs on the small Norwegian island of Fugloy due to its huge seabird colonies, with late summer numbers boosting to 75 eagles, all within an area of only . Five occupied nests were noted on an stretch of the Russian
Yenisei River The Yenisey (russian: Енисе́й, ''Yeniséy''; mn, Горлог мөрөн, ''Gorlog mörön''; Buryat: Горлог мүрэн, ''Gorlog müren''; Tuvan: Улуг-Хем, ''Uluğ-Hem''; Khakas: Ким суғ, ''Kim suğ''; Ket: Ӄук, ...
. Mating chiefly occurs between mid-March and mid-April in most parts of the range. The pair may copulate be about once every 20 minutes for several hours. Prior to mating, a more skilled and graceful flying than usual may be undertaken by the male as the final stage of courtship. After his final display, the female crouches low, almost flat, with her head and neck outstretched, wings half open, and tail held level with the rest of the body. Mating has been recorded in white-tailed eagles to occur almost anywhere including a low perch, on the nest, on the ground or even on frozen lake surfaces, usually close to the nest at least but also at as far away from the nest as in Norway. Sometimes both members of the pair will assume the female's typical mating position simultaneously side-by-side until he jumps on her back. Once the male mounts he often calls loudly and flaps both wings to maintain his balance. After about 12 seconds he dismounts and sits quietly, ultimately will do so about 5 to 6 in 1.5 hours and at nearly any time of the day.


Nest characteristics

White-tailed eagles most often nest in large trees, with perhaps coniferous trees preferred and nests may be in a high main fork, on the canopy or a large side branch. Access to food is a key consideration in the nest's location in white-tailed eagles. In Germany, 75% of eyries were within of a lake, although one was away from any lake though was somewhat closer to the Baltic Sea.Oehme, G. (1961). ''Die Bestandsentwicklung des Seeadlers, ''Haliaeetus albicilla'' (L.). Deutschland mit Untersuchungen zur Wahl der Brutbiotope''. In: Schildmacher, H.: Beiträge zur Kenntnis deutscher Vögel. Jena, pp. 1–61. 80% of German nests were described as being in forests but eagles exhibited preferences for wooded islands or promontories and most nests were usually towards edge of open space: a clearing, marshy ground or even agricultural land. Among the few eyries in open land were never more than away from woods. Only one cliff nest was recorded in Germany, on the Baltic island of Rugen. Older records indicated ground nests also recorded in the German Baltic region. Most German nests were at heights from off ground in the main fork of trees, rarely on ample horizontal tree branches. Tree nest height is partially based on tree species, i.e. in Romania, on black poplars (''Populus nigra'') and
willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...
s nest height would was recorded at of the ground but one was on a broken tree at only from the ground. There in the lower Danube of Romania beyond the mainly utilized black poplars and willows, one was on "a weak oak sapling", six on high, thick oaks, five in white poplars (''Populus alba''), two in
beech Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engl ...
es and one in a wild
pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosacea ...
tree. Another quote on eyrie height along the Danube was at above the ground. Trees used for nests in Hokkaido were often the tallest in a stand, averaging higher than the average tree height in their stand. Tree species preferred here were '' Picea glehnii'' and ''
Alnus japonica ''Alnus japonica'', known as Japanese alder, is a species of Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a larg ...
''. Nest height in Hokkaido was similar to that in Europe at above the ground. In eastern Germany, among 177 nests, 65% were in mature pines, 22% in copper beeches (''Fagus sylvatica''), 8% in oak with the remainder in alder, elm, poplar and
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...
. The German eyries ranged in height from , averaging , usually in tallest trees available. Nests can be on crags, whether or not trees may be available, depending on regional habitat. In 98 Norwegian eyries, only eight were in trees, the rest were on cliffs. In comparison, against the 86% nests that were on cliffs in Norway, 79% known in Scotland were too, 77% in Iceland and all known Greenlandic nests were in cliffs or other rocky spots.Christensen, J. (1979). ''Den Grönlandske havörns ''Haliaeetus albicilla'' groenlandicus Brehm ynglebiotop, redeplacering og rede.(with English Summary: The breeding habitat, nest-site and nest of the Greenland White-tailed Eagle ''Haliaeetus albicilla groenlandicus'' Brehm.)''. Dansk Orn. Foren. Tidsskr, 73, 131–155. Nest height on cliffs can be over above the nearest flat ground. Rarely, they may nest on the ground or a low hummock, as well as smaller trees, low bushes, on sand banks or among reed beds. Showing their adaptability, one pair even nested on a
buoy A buoy () is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. Types Navigational buoys * Race course marker buoys are used for buoy racing, the most prevalent form of y ...
on a Norwegian shipping route. Nests are usually huge, constructed of sticks and branches, averaging roughly across and up to deep, but can be several metres in width & depth, lined variously with moss, greenery, seaweed or wool. The nest must have easy access for the eagles with a clear view of the surrounding environment, shelter from the elements and protection from nest predators. In forest of Finland, it has been estimated that perhaps only one in a thousand trees will prove attractive to white-tailed eagles. Cliff nests often include lesser materials, some may be only a scooped shallow depression of soil, or pile of heather or juniper stems with stipes of dried '' Laminaria'', but also sticks up to and several cm thick may be incorporated; almost any material available may line the nests such as seaweed, driftwood, even glass or metal floats and, in one to two cases, the dried skeleton a sheep. In tree nests, the average nest diameter is about , with nests in trees tending to be larger, more rigid and stronger. A relatively new four-year-old nest weighed and one about twice that age can exceed in mass. Some tree nests may range easily up to in diameter and deep after many repairs over years, with extreme sizes of perhaps another metre in diameter and depth, or "twice the height of a man". Tree nests may be lined with
lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...
,
seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and '' Chlorophyta'' (green) macroalgae. Seaweed species such as ...
,
fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...
s,
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
, woodrush, heather or ''
Empetrum ''Empetrum'' is a genus of three species of dwarf evergreen shrubs in the heath family Ericaceae. They are commonly known as crowberries and bear edible fruit. They are commonly found in the northern hemisphere, from temperate to subarctic clima ...
''; many tree nests may be lined with sheep's wool. The male of the pair more often brings nesting branches, while the female takes the primary role in construction. A nest may be added to by the resident pair at as early as December onwards, but usually do so starting in March at high latitudes. A new nest may take several months to construct, but if an old nest is lost in late winter, pairs have been known to build a new nest faster than average in less than a month, however egg laying may be inhibited in such cases. Repair to an existing nest can take about 18 days. White-tailed eagles have also used nests built by other species: black kite,
common buzzard The common buzzard (''Buteo buteo'') is a medium-to-large bird of prey which has a large range. A member of the genus '' Buteo'', it is a member of the family Accipitridae. The species lives in most of Europe and extends its breeding range acr ...
,
common raven The common raven (''Corvus corax'') is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. It is a raven known by many names at the subspecies level; there are at least ...
(''Corvus corax'') and, subsequent to the eagles evicting them,
osprey The osprey (''Pandion haliaetus''), , also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor reaching more than in length and across the wings. It is brown o ...
s and red kites. Eastern imperial eagles, saker (''Falco cherrug'') and
peregrine falcon The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a cosmopolitan bird of prey (raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey bac ...
s have used old white-tailed eagles nests, in the two swift falcon species they've been recorded in evicting pairs of white-tailed eagles from their eyries with persistent dive-bombing. In one case, after having been displaced by humans from an eyrie that had seen 30 years of white-tailed eagle use, an eagle pair returned to find the nest occupied by peregrine falcons. Despite many dogfights, the eagles constructed a nest higher up in the same tree. Although fighting continued, both species succeeded in raising one fledgling each. In Norway, pairs of ravens, peregrines and white-tailed eagles have been known to successfully nest on the same cliff face. Many small species of bird may nest in the immediate area of white-tailed eagle eyries, presumably due to incidental protection:
Eurasian tree sparrow The Eurasian tree sparrow (''Passer montanus'') is a passerine bird in the sparrow family with a rich chestnut crown and nape, and a black patch on each pure white cheek. The sexes are similarly plumaged, and young birds are a duller version ...
(''Passer montanus''), white wagtail (''Motacilla alba''), Eurasian treecreepers (''Certhia familiaris''),
common redstart The common redstart (''Phoenicurus phoenicurus''), or often simply redstart, is a small passerine bird in the genus '' Phoenicurus''. Like its relatives, it was formerly classed as a member of the thrush family, (Turdidae), but is now known to b ...
s (''Phoenicurus phoenicurus''), European crested tits (''Lophophanes cristatus''), Eurasian starlings and stock doves (''Columba oenas''). Like in the golden eagle, pairs of white-tailed eagles often build multiple nests on their home range over time and use them randomly over different years (sometimes using one for several consecutive years or changing nests every year over several years). The species may build from 1 to 11 nests, averaging 2.5 in Norway with pairs with up to five nests being not uncommon in that country.


Eggs and incubation

Individual white-tailed eagles tend to be remarkably consistent on egg-laying times from year to year, seemingly regardless of surrounding weather conditions. Egg laying does vary of course by latitude. Historic breeders from
Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
and Iran (where they still usually breed) were reported to lay eggs in January, while in Greece and the lower
Volga river The Volga (; russian: Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catch ...
it is during February, in Germany mostly during March and in the subarctic of
Lapland, Finland Lapland ( fi, Lappi ; se, Lappi; smn, Laapi; sv, Lappland; la, Lapponia, links=no) is the largest and northernmost region of Finland. The 21 municipalities in the region cooperate in a Regional Council. Lapland borders the region of North ...
and northern Russia, to as late as late April to early May. White-tailed eagles in Scotland seem to have average egg laying about three weeks later, late March to early April, than those in coastal Norway. Even near Arctic in Finland, eggs were found as early as 5 March despite ranging often to as late as May. Younger pairs may nest later on average than older ones. In white-tailed eagles, many (perhaps a majority) of clutches consist of two eggs, especially in Irish and Scottish nests, with three egg clutches being considered uncommon to rare there. Four egg clutches have been recorded on the
Isle of Skye The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated b ...
, as well as in at least Poland, Romania and Norway. Clutch size in Scotland averages 1.56, while in Norway it is 2.16. The eggs are a broad oval shape and dull white in colour, sometimes with a glossy sheen and are usually unmarked but for occasional yellowish stain. Fresh egg weigh from , with an average of approximately for the first egg and for the second. If replacement clutch is laid, usually a single egg is laid which may weigh as little as .Fentzloff, C. (1977). ''Successful breeding and adoption of sea eagles (''Haliaeetus albicilla'')''. Papers on the veterinary medicine and domestic breeding of diurnal birds of prey, pp. 71–91. Average egg dimension seem to keep in accordance with the female body size, smallest mean size known were from Turkey where the average dimensions were to the largest in three surveys from Greenland, where they were . In 54 eggs from Scotland they ranged from , averaging , in height by , averaging , in width. In comparison, 90 eggs from mainland Europe ranged from , averaging , by , averaging . Eggs may be compromised quickly by frost and snow in relatively early clutches. Incubation starts as soon as the first egg is laid. In the species, a 2–3 day interval between the first and second egg being laid (as well as hatching) is recorded. The female does up to 80–90% of incubation and all known nighttime incubating. However, in Norway, the male of a pair could contribute up to about 27% of incubation to daylight hours. There may be as many as 11 changes of the incubating individual within a day. The longest period recorded the clutch was unguarded was 20 minutes, although one pair perched nearby the nest without incubating for 48 minutes. The clutches in Norway left alone only 2–4% of the time. In some cases female may do all the incubation alone, however. When the female is off the nest, she sometimes kills prey and returns with a full crop, but prey capture during incubation is often up to the male. Late into incubation, shift changes decreases and the female will sit tight and will crouch down at the approach of a human rather than leave the nest. Calling and displaying are reduced during incubation, but occasionally both may leave the clutch and display still. The time range for incubation can vary from 34 to 46 days, but usually are between 38 and 42 days. A calculated mean time range for incubation of 38.3 days.


Hatching, development and fledgling

In 1983, it was listed that brood size is one 56.5% of the time and two 40.8% of the time in eight studies from different parts of the range; only 2.5% of these studies had a brood size of three and only one from Norway was a brood size of four recorded. From 14 studies, the mean number of chicks in a brood may range from 1.1 in western Germany to 1.9 in southern Kazakhstan, with average overall brood size of 1.52. However, these datasets may be skewered lower than natural brood size as a majority these are from the mid to late 20th century when pesticide use considerably lowered the mean number of hatchlings in many parts of the range. New hatchlings will weigh about but in Hokkaido new hatchlings were surprisingly notably heavier at . The sex of nestlings can be identified using field methods, or using DNA. Initially, the hatchlings have a creamy white down which is longest and whitest on the head and often dirty grayish on wings and rump. Before they start walking about the nest, their underside may have several bare patches. The nestlings first become audible at around 2–3 days and have become active enough to move around the nest and excrete over the nest edge by 10 days old. The initial down is replaced by a thick woolly coat of longer, coarser grayish down, which is usually darker on the crown, underparts and flanks. The legs and cere at this young nestling age can range from pinkish to pale yellow. By about 30 days the first feathers poke through the down. The eaglets can feed themselves starting at 35–40 days. At six weeks (40 days) they are more firm on their feet and between this and the following week feathers take over the down, with patches of down remaining but usually gone by the seventh week. Wing flapping begins only when the wings are partially feathered at 42 days. Around seven weeks of age, the eaglet is more alert and stronger and frequently manipulates sticks and walks more so. At eight weeks, only the long feathers of the wing and tail have yet to develop fully and eaglets tend to start exploring the surrounding branches. The eaglets will attempt their first flight at about 70 days and will usually be flying well by about 90 days of age. Fledgling occurs around mid- to late July in Norway, and about 3–4 weeks later in Russian White Sea. The female of the white-tailed eagle pair seems to do all the brooding early on and will be especially reluctant to leave the nest as well. Thereafter, at 14 to 28 days, brooding behaviour by the female gradually declines. The male may start to brood occasionally around this time period but will not do so at night. Females may sit on the nest or shelter the fledglings from rain even 28 days after fledging but usually such behavior is much reduced. Chicks may be fed as many as 11 times in 24 hours by the female who usually dismantles prey brought by the male. To 28 days, male continues to do most of the prey capture but thereafter female does much of it and both parents begin to leave kills on the nest for the eaglets to consume. As the chicks grow older, favored food often switches from fish to birds to meet their increasing food requirements as well as prey behavior as waterfowl may be flightless during
eclipse An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three c ...
. Caches are often depleted quickly late into nestling development. At start of fledgling, 4–5 carcasses may be brought in a week but by the end of fledgling, only one or two are usually brought, probably to encourage the young to start their own prey captures. After leaving the nest, the young usually stay nearby for another 35–40 days and may still be largely fed by their parents but gradually learn to take their own prey. In continental Europe, the young eagles are gone from the nest as early as the beginning of July to about 10 August and fully independent by late August. In this late summer stage, they may learn quickly to feed on stranded fish or to capture ducks flightless in eclipse. Juvenile eagles may remain for a long time on their parents range and apparently are not resented or repelled even to the ages of 1–3 years. However, usually by their first winter they will have congregated with other unrelated juveniles. Communal juvenile roosts in Norway can maintain 30–40 white-tailed eagles usually in trees or steep slopes of offshore islands. Sexual maturity is reached at 5–6 years of age.


Nesting failures and longevity

Normally, white-tailed eagles succeed in raising one or two young from a clutch of two, and two from a clutch of three. The average breeding success seems to be about 1.1–1.6 young per annum (i.e. 45–48 young from 40 observed cases, with 16 failures) (1.6 young per pair in 93 recorded Norwegian nests). About 33% of nesting attempts will fail to produce any young, and this is sometimes as many as 75% (at times of heavy persecution or pesticide use). Beyond manmade threats to white-tailed eagle nestlings, starvation and nest collapse are considerable causes of nestling deaths. Natural threats in the nest may also include siblicide (or "cainism") wherein the largest nestling behave aggressively and gradually kill their smaller sibling, which is often consumed. Despite claims to contrary, siblicide in white-tailed eagle does occur with some regularity in some parts of the range, from Germany to Hokkaido although is certainly less frequent than in some eagle species, including the
golden eagle The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known bird ...
. Single cases were reported in the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
and Iceland, and it may occur situationally as in many birds of prey when prey populations are low or prey capture is inhibited by poor weather. Siblicide can be avoided in white-tailed eagles with manipulative techniques, which may include taking out and hand-rearing the runt, put a chick into a nest with slightly younger brood which it is about the same size as, or taking the first egg out and putting it back in later so it develops evenly with its younger sibling. Surplus chicks are sometimes removed from nests to use in
reintroduction Species reintroduction is the deliberate release of a species into the wild, from captivity or other areas where the organism is capable of survival. The goal of species reintroduction is to establish a healthy, genetically diverse, self-sustainin ...
programs in areas where the species has died out. If left in the nest, they often die sooner or later, as with most large eagles. In such programs the birds are raised in boxes on platforms in the tree canopy and fed in such a way that they cannot see the human supplying their food, until they are old enough to fly and thus find their own food.Meyburg, B. U. (1975). ''Protective management of eagles by reduction of nestling mortality''. World Confer. Birds of Prey, Vienna, pp. 387–391. Known natural predators of white-tailed eagle eggs and nestlings include
red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the Order (biology), order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe ...
es,
marten A marten is a weasel-like mammal in the genus ''Martes'' within the subfamily Guloninae, in the family Mustelidae. They have bushy tails and large paws with partially retractile claws. The fur varies from yellowish to dark brown, depending on ...
s and
bear Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the No ...
s, especially if nesting in overly accessible rock formations, while
wild boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species i ...
s have been recorded eating eggs and nestlings that’ve fallen out of the nest too early. Avian predation, overall a seemingly rare occurrence, of white-tailed eagle eggs and nestlings have been reported as crows,
common raven The common raven (''Corvus corax'') is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. It is a raven known by many names at the subspecies level; there are at least ...
s and western marsh harriers, which are likely to succeed in cases where nest attendance is low or if successful in driving away the parents via fierce mobbing. Furthermore, Eurasian eagle owls have been reported to prey upon "fairly large" nestlings of white-tailed eagle in nighttime ambushes. Many juveniles do not survive their first year post-independence. In the 1970s, an average of 56% banded first-year white-tailed eagles in Norway, Sweden and Greenland were found dead, most often having been shot.Helander, B. (1975). ''Havsörnen i Sverige''. Fören. In eastern Germany, of 194 white-tailed eagles found dead between 1946 and 1972, of those where cause of death could be determined, 39% had been shot, accidents (especially powerlines) accounted for 6%, territorial disputes 7.5% and conservatively 13% were from poisoning. It is estimated that the survival of those that reach adulthood at 70%. Another estimate of average lifespan for those who reach adulthood is just over 12 years. Widely reported individuals have been found to live for 25 years or more, Another estimate of mean lifespan (presumably without persecution) is 21 years. At one point, the oldest banded white-tailed eagle known in the wild known lived for 27 years. However, a wild eagle of the species was subsequently recorded to life for 33.1 years. White-tailed eagles in captivity have lived for more than 40 years, though their exactly captive longevity record is not known. A male white-tailed eagle that was ringed as a chick on the
Isle of Skye The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated b ...
in 1994, was recorded on the
Isle of Mull The Isle of Mull ( gd, An t-Eilean Muileach ) or just Mull (; gd, Muile, links=no ) is the second-largest island of the Inner Hebrides (after Skye) and lies off the west coast of Scotland in the council area of Argyll and Bute. Covering ...
in early 2022 at the advanced age of 28 years old. His mate, a female white-tailed eagle that hatched in 1992 on Mull, will now be 30 years old although her identity has not been confirmed.


Relationship with humans


Extirpations

The white-tailed eagle formerly bred over much wider area, extending west to much of
western Europe Western Europe is the western region of Europe. The region's countries and territories vary depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean ...
and perhaps south almost continuously in that region to the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...
. From the 19th century, the species underwent a huge, well-documented decline. Ultimately the white-tailed eagle was almost extinct in Europe, extirpated from all but
Fennoscandia __NOTOC__ Fennoscandia ( Finnish, Swedish and no, Fennoskandia, nocat=1; russian: Фенноскандия, Fennoskandiya) or the Fennoscandian Peninsula is the geographical peninsula in Europe, which includes the Scandinavian and Kola penin ...
(mainly remaining in Norway) and some sparse patches of
eastern Europe Eastern Europe is a subregion of the European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural, and socio-economic connotations. The vast majority of the region is covered by Russia, whi ...
. They were extinct in the entire
British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isl ...
by the early 1900s. At one time, the white-tailed eagle bred down to
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...
in Africa, particularly around Lake Manzala with individuals wandering rarely to
Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...
and
Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...
. It is likely that habitat degradation and drying conditions caused the extirpation of the species as all but a vagrant in Egypt. Two pairs that nested in the Jordan Valley ceased to breed, apparently due to agricultural chemicals, in the early 1950s. The species also once bred in northern
Syria Syria ( ar, سُورِيَا or سُورِيَة, translit=Sūriyā), officially the Syrian Arab Republic ( ar, الجمهورية العربية السورية, al-Jumhūrīyah al-ʻArabīyah as-Sūrīyah), is a Western Asian country loc ...
but is not found reliably there even in winter in modern times.


Causes of decline

In Britain, the opinion towards white-tailed eagles became negative in sync with the creation of farmland and commercial fishing, as it was quickly perceived that they were competitors for resources and could deplete the livelihood of flocks for shepherds (despite this being largely untrue) and game animals for gamekeepers. Therefore, laws were passed to facilitate their destruction. Already by the end of the 18th century, down from breeding in all appropriate habitat, the English population was down to only localized breeding, namely in the
Isle of Wight The Isle of Wight ( ) is a county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the largest and second-most populous island of England. Referred to as 'The Island' by residents, the Is ...
,
Lundy Lundy is an English island in the Bristol Channel. It was a micronation from 1925–1969. It forms part of the district of Torridge in the county of Devon. About long and wide, Lundy has had a long and turbulent history, frequently chang ...
,
Isle of Man ) , anthem = " O Land of Our Birth" , image = Isle of Man by Sentinel-2.jpg , image_map = Europe-Isle_of_Man.svg , mapsize = , map_alt = Location of the Isle of Man in Europe , map_caption = Location of the Isle of Man (green) in Europ ...
and (probably) near
Plymouth Plymouth () is a port city status in the United Kingdom, city and unitary authority in South West England. It is located on the south coast of Devon, approximately south-west of Exeter and south-west of London. It is bordered by Cornwall to ...
; within a couple of decades the species only remained in the
Lake District The Lake District, also known as the Lakes or Lakeland, is a mountainous region in North West England. A popular holiday destination, it is famous for its lakes, forests, and mountains (or '' fells''), and its associations with William Wordswor ...
. Before the advent of firearms, few people in England and Scotland were highly motivated to kill eagles since this could be time-consuming and hazardous process, therefore the British government rose the bounty on eagles to a very high 5 shillings a head by the turn of the 18th century. Unfortunately, eyries in many coastal sites were found to be easily accessible so that destroying or selling eggs was common. Subsequent to systematic persecution, in Greenland 62% of eyries found to be "easily accessible" and only 13% foiled all attempts to reach them. Similar findings were found in sea cliff nests in Iceland, Norway and Scotland. White-tailed eagles are more vulnerable to direct persecution than golden eagles since most nests are highly accessible for white-tailed eagle but not for golden eagles which usually nest in mountainous, precipitously rocky terrain, in contrast to sea cliff nests of which 67–87% were found to be accessible. Before firearms were widely available in Scotland and Norway automatic traps were utilized wherein carrion was laid out to entice an eagle with a person hiding in a near subterranean trap waited until the eagle was distracted, at that point grabbing the eagle by the leg. Petrified by the darkness once dragged below, white-tailed eagles apparently offer no resistance once caught. However, habitat had to be favorable and even when conditions were correct, success at capture as such was low. The main driver of declines before firearms and industrialized poisons was habitat alterations. After about the 1840s, firearms became available and declines accelerated considerably, by 1916 the last nesting pair in all of Britain attempted to raise a brood on the
isle of Skye The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated b ...
. While other ecological factors have been considered in this decline, stringent research has shown the extirpation here was fully correlated to intentional, rapacious predation by man. Many gamekeepers poisoned and shot eagles and destroyed nearly any nest they encountered. A few more enlightened landowners forbade the killing of eagles but there's evidence that the gamekeepers sometimes chose to destroy eagles regardless of the rule of law. On deer forest, eagles were tolerated later than in other British areas, but destructions accelerated there by the late 1800s. Also many white-tailed eagles were poisoned by shepherds who considered it enemy of the flock. Elsewhere in Europe, persecution rates in the 19th and 20th century were just as drastic. In Romania, more than 400 white-tailed eagles were killed in two decades by a single hunter. In Norway between 1959 and 1968, an average of 169 eagles were killed annually; with a maximum of 221 in 1961. Around the year 1860, an author estimated that about 400 were being killed annually throughout Germany. Between 1946 and 1972 in eastern Germany, a total of 194 dead white-tailed eagles were found, about half of them shot, after governmental protection of the species had been instituted there. Top predators, especially those that are aquatic and coastal, are almost immediately vulnerable upon exposure to DDT. Therefore, white-tailed eagles are highly susceptible to this pesticide, as are similar fish eaters, such as otters, and bird eaters, such as
peregrine falcon The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a cosmopolitan bird of prey (raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey bac ...
s. Distributed by man nearly across the developed world as an insecticide in the 1950s, by the early 1970s, authors found many species of bird experienced reduced egg shell thickness. Thus the incubating parents inadvertently crushed their normally hardy eggs and, in turn, many water birds and raptors had their nesting success dropped precipitously.Newton, I. (2010). ''Population ecology of raptors''. A&C Black. In fact, the species was found to have the highest concentration of DDT of any European raptor. Egg shell thickness was found down from prior to 1935 from 1969 to 1975 down to only , a 16% reduction. In Sweden, coastal birds were considerably more effected by DDT than the inland birds of Lapland, Sweden. In eastern Germany, where pesticide use was heavy, only 1 out of 28 nesting attempts were known to succeed in 1976. Overall, about 75% nesting attempts failed in western Germany, Finland and the Swedish Baltic area. Other environmental pollutants affecting the species include heavy metals which affect individuals through
bioaccumulation Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
. The amount of white-tailed eagles killed by mercury poisoning rose from 6.4% during 1946–1957 to 24.6% in 1958–1965 in Germany. It was estimated that pesticides and metal contaminations reduced the white-tailed eagle population in Hungary from 1957 to 1967 by about 50–60%. Lead poisoning, caused by lead bullets left in carcasses that the white-tailed eagles will eat in winter, is also another issue faced by the species. Fatal and near fatal levels of lead exposure continues to be a major issue in the 21st century in many parts of the range, at least from Poland to Hokkaido. Despite regulations on their usage, lead and mercury poisonings were found to be the cause of death of 61 white-tailed eagles found in Germany from 1993 to 2000.


Conservation measures

In order to offset the numerous chemical and metal based poisoning that humans were inadvertently exposing the species to, a widespread operation was undertaken to feed white-tailed eagles uncontaminated foods in Sweden. Here, carcasses from slaughterhouses placed in areas free of human disturbance, usually fields, bogs, marshes or frozen lakes, from October to March (after these months, the eagles will ignore carrion in favor of capture of live prey). Apparently, breeding success improved from 29% to 44% when the program began. In southern Sweden subsequent to the feedings, 5 of 11 breeding pairs were successful and two previously unoccupied territories were taken over by new pairs, thus winter feeding was seemingly highly beneficial to local eagles. Similar winter feeding stations set up in Finland from 1972 to 1978. In Sweden, brood size has varied from 1.3 per nest prior to 1950, down to 0.3 in 1965–1985. Now the brood sizes have increased, at somewhat less than one brood size on average, but still somewhat less productivity than historical numbers. In several parts of the European range, especially southern Scandinavia and central Europe, protections have allowed white-tailed eagles to recolonize former parts of their range. Since recolonizing
Schleswig-Holstein Schleswig-Holstein (; da, Slesvig-Holsten; nds, Sleswig-Holsteen; frr, Slaswik-Holstiinj) is the northernmost of the 16 states of Germany, comprising most of the historical duchy of Holstein and the southern part of the former Duchy of Sc ...
, Germany in 1947, numbers have increased slowly; from 1975–2008, increases were recorded at 6.7% in population per annum and enjoyed much higher productivity. Perhaps particularly key has been conserving white-tailed eagle habitats. In the 1970s, 75% of the potential and current white-tailed eagle territories became protected in Schleswig-Holstein. In Poland, 78% of forests are state owned and clusters of 10 or more trees are preserved around each white-tailed eagle eyrie. The Swedish Forest Service limits logging activities to within of a nest tree which expands to within during breeding season; however this acts not as a law but only as an advisory where the eyries are located on private land. Limits on recreational activity were established as these can disturb white-tailed eagle nests especially in well-trodden countries such as Germany and Sweden, but even in the remote Russian Kandalaksha. In northern Finland, artificial eyries were constructed for their use. Out of 19, 14 were visited by white-tailed eagle, eggs laid in at least nine, and two ultimately fledged young. Regulations have been established on direct use of pesticides that harm white-tailed eagles such as DDT, however because of political variances, despite widespread monitoring, not at all areas are strictly protected.Movalli, P., Dekker, R., Koschorreck, J., & Treu, G. (2017). ''Bringing together raptor collections in Europe for contaminant research and monitoring in relation to chemicals regulations''. Environmental Science and Pollution Research, 24(31), 24057–24060. Similarly, regulations on lead usage in hunting has been inconsistent in comparison with the stronger efforts to ban lead bullet fragments in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
. The residuals of mercury from various fungicides (now banned), air particles and pollution run-off water have caused huge concentrations in fish of many different areas, which continues to effect humans as well as entire ecosystems of wildlife. Unfortunately, methylmercury is still difficult to manage in Europe as it is elsewhere.


Reintroduction

The first attempts at
reintroduction Species reintroduction is the deliberate release of a species into the wild, from captivity or other areas where the organism is capable of survival. The goal of species reintroduction is to establish a healthy, genetically diverse, self-sustainin ...
in Scotland were in 1959 in Glen Etive,
Argyll Argyll (; archaically Argyle, in modern Gaelic, ), sometimes called Argyllshire, is a historic county and registration county of western Scotland. Argyll is of ancient origin, and corresponds to most of the part of the ancient kingdom of ...
abortively, followed by a better informed but also ultimately unsuccessful attempt on Fair Isle in 1968. Successful reintroduction into Scotland did not occur until the 1970s, with the isle of
Rùm Rùm (), a Scottish Gaelic name often anglicised to Rum (), is one of the Small Isles of the Inner Hebrides, in the district of Lochaber, Scotland. For much of the 20th century the name became Rhum, a spelling invented by the former owner, Sir ...
in the
inner Hebrides The Inner Hebrides (; Scottish Gaelic: ''Na h-Eileanan a-staigh'', "the inner isles") is an archipelago off the west coast of mainland Scotland, to the south east of the Outer Hebrides. Together these two island chains form the Hebrides, whi ...
being chosen because of its large size () with access to the
Isle of Skye The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated b ...
(where last native pair known in Britain last bred in 1916) and it is only from the mainland. Also Rùm hosts large seabird colonies that make for viable prey, including eider (''Somateria mollissima''), shag (''Phalacrocorax aristotelis''),
auk An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word "auk" is derived from Icelandic ''álka'', from Old Norse ''alka'' (a ...
s and
gull Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century ...
s; as well as one of the few in Britain of
manx shearwater The Manx shearwater (''Puffinus puffinus'') is a medium-sized shearwater in the seabird family Procellariidae. The scientific name of this species records a name shift: Manx shearwaters were called Manks puffins in the 17th century. Puffin is a ...
(''Puffinus puffinus''). Furthermore, mainly as a source of carrion, were a population of around 1500
red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of ...
and 200 feral
goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...
s; otters and gulls were also numerous and available to kleptoparasitize. The birds to be used for reintroduction were gathered as nestlings from western Norway, as this is the nearest native breeding population. The young eagles were either kept in high grade fowl cages or tethered all within reach of an artificial eyrie, cover and feeding stations. Direct human contact, which the naturally wild young eagles tended to shun anyway, is minimal short of veterinary care. Releases were carried by taking bird out tethered, wearing a leather hood to prevent imprinting and then releasing with a radio-monitor. Most of the eagles, despite no direct parenting, turned out to be competent hunters within a couple of weeks or do well at stealing meals, including from other released eagles. Despite some dying before release due to illness and some found dead subsequent to release, most survived. A total of 95 birds were received for the Rùm reintroductions and 82 were successfully released between 1975 and 1987. The white-tailed eagle now breeds throughout the Western Isles and the mainland coast of Wester Ross. However, a low reproductive output of reintroduced Scottish eagles was recorded in 1996, and it was advocated that additional releases were needed. In August 2008, an additional fifteen chicks raised in Norway were released at a secret location in
Fife Fife (, ; gd, Fìobha, ; sco, Fife) is a council area, historic county, registration county and lieutenancy area of Scotland. It is situated between the Firth of Tay and the Firth of Forth, with inland boundaries with Perth and Kinross ...
, in expectation of reintroducing the species to the east coast of Scotland as well. Breeding success of reintroduced birds in Scotland (from 1975–1985 & 1993–1998) is moderate compared overall in species, in 1982–1992: productivity was 0.38, with a mean fledgling number 1.61. In comparison, for the years 1993 to 2000, productivity was 0.61 and fledgling number was 1.48, while in 2000–2007, productivity was 0.7 and mean fledgling number 1.44. Overall in Britain, there are estimated 36 breeding pairs in 2006 and 40 in 2008. Juvenile survival rates are somewhat low overall compared to other areas. Reintroduction efforts succeeded in the
Bohemia Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region of the Czech Republic. Bohemia can also refer to a wider area consisting of the historical Lands of the Bohemian Crown ruled by the Bohem ...
area of the Czech Republic as well, where the biologists similarly followed the guidelines of guarding of occupied eyries and provision of safe foods. The white-tailed eagle is also being reintroduced to Ireland, where its Irish name of Iolar Mara (sea eagle) reflects its historic association with the island's long coast. The Irish program was begun in the summer of 2007. Fifteen to twenty young eagles from Norway are being released each spring into the
Killarney National Park Killarney National Park ( ga, Páirc Náisiúnta Chill Airne), near the town of Killarney, County Kerry, was the first national park in Ireland, created when the Muckross Estate was donated to the Irish Free State in 1932. The park has sinc ...
in the south-west of Ireland. This comprehensive project will last a number of years, with many more eagles being released. The species has a rich history on the island but became extinct in Ireland in the 1900s due to persecution from landowners. The last pair bred on the coast of Mayo in 1912. In 2007, a hundred local sheep farmers gathered at Kerry airport to protest the eagles' arrival. Irish Farming Association Hill Committee chairman Mr O'Leary said he had no doubt the eagles would take lambs. Since their reintroduction seven eagles have been confirmed poisoned in County Kerry, two suspected of having been poisoned, and one shot. A 13th eagle released in Kerry was shot in
Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label=Ulster Scots dialect, Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is #Descriptions, variously described as ...
. Twenty more eagles were due for release in 2010. However, Dr Allan Mee, in charge of the sea eagle project, stated "the continuing loss of eagles to poisoning had cast a shadow over the future of the ambitious programme." The first white-tailed eagle breeding pair since 1912 nested one hundred years later on Lough Derg (Loch Deirgeirt), marking a great success for the Irish reintroduction programme. In early May 2013, the first eaglets were born in Ireland since the re-introduction programme began; one in the Killarney National Park and two in County Clare. In Spring 2015, five nests hatched chicks in four counties in Ireland – Clare, Cork, Galway and Kerry. In 2019, a reintroduction project on the
Isle of Wight The Isle of Wight ( ) is a county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the largest and second-most populous island of England. Referred to as 'The Island' by residents, the Is ...
was approved by the British government. It is hoped that establishing a breeding population in the coastal county will lead to the species re-colonising the South Coast. Following the release of six juveniles on the island in 2019, individuals were sighted across Southern England, and one of the six, a male named Culver (after Culver Down, a local landmark on the Isle of Wight near the town of Sandown) embarked on a tour of South-East England shortly after being released, and was sighted over Central London after ranging through Hampshire, East Sussex and Surrey, continuing through Essex, Kent and West Sussex. In May 2021, the group leading the Isle of Wight reintroduction project, the Roy Dennis Wildlife Foundation, were given permission by Natural England to start a second reintroduction project, this time in
Norfolk Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the Nor ...
, thus reintroducing the white-tailed eagle to
East Anglia East Anglia is an area in the East of England, often defined as including the counties of Norfolk, Suffolk and Cambridgeshire. The name derives from the Anglo-Saxon kingdom of the East Angles, a people whose name originated in Anglia, in ...
. Up to 60 birds are to be released over a span of 10 years at Wild Ken Hill in West Norfolk.


Current status

Densities of white-tailed eagles have greatly increased in some parts of the range due to conservation efforts. Some threats still remain, notably illegal persecution by gamebird shooting and egg thieves in Scotland. In prime habitat in north Europe, distance between breeding pairs can be only (even as little as locally) such as in Norway, density at one Polish forest were even reported at 6–7 in each square kilometer. In the late 1990s, it was estimated that Russia held as many as 5,000 to 7,000 pairs, with around 175 pairs in Greenland and almost 3,500 pairs in
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
, led by Norway (1,500+ pairs), European Russia (900–1,100), Poland (180–240), Germany (140–150) and Sweden (100–150). The largest population in Europe is found along the coast of Norway. The Norwegian population in 2008 was claimed to have stood at 9,000–11,000 pairs, much larger than prior estimates, and indeed this may refer to the total number of individuals rather than total breeding pairs. Even in the early 1980s, Norway maintained a population greater than all other European white-tailed eagle populations combined. In isolation, Turkey holds merely 10–30 pairs. Over 500 winter in Japan, mainly Hokkaido, but this island may have only 20 pairs breeding. Strong increases were recorded in Croatia, with no less than 135 breeding pairs estimated in Croatia by 2009, up from only 25–30 in 2007. Beyond the threat of chemical poisonings, a new threat from
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each year. ...
s is emerging with significant mortality (considerably in excess of the area's population productivity) occurring at the Smøla Wind Farm in Norway. From 2005 to 2010, 36 birds were killed by wind farm on the isle of
Smøla Smøla is a municipality in Møre og Romsdal county, Norway. It is part of the Nordmøre region. The administrative centre of the municipality is the village of Hopen, other villages include Dyrnes, Råket, and Veiholmen. The municipality ...
, including four of the 45 recent radio-tagged fledglings. Breeding attempts within of the wind farm were considerably reduced in success. The white-tailed eagles of the region seem to have no behavioral avoidance capabilities, as in many raptors, since the blades are not visible at close range. In a recovering population in north-east Germany, a trade-off between the distance to neighbouring breeding pairs and to the nearest water body (the birds' favoured foraging habitat) was found. This indicates that pairs may be increasingly selecting suboptimal habitats to reduce competition as the population increases, and has implications in the management of such populations. White-tailed eagles have apparently re-established themselves as a native breeding species in numerous countries: Austria (now breeding in extreme northwestern portions), Denmark (where broadly re-established as breeders), the
Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...
and Slovakia (scattered pairs in both now with reintroductions factoring in the Czech Republic), Hungary, and Bulgaria. In Denmark (excluding Greenland where the species never was extirpated as a breeder and there are 150–200 pairs in the south), the breeding population increased from none in 1995 to at least 37 pairs by 2011. In 2021, there were more than 150 breeding pairs in Denmark, far surpassing the initial goals of the species' recovery program in the country. From 1996 when the first pair bred to 2021, altogether more than 1,350 young have fledged. In Hungary, re-establishment (starting from none in the 1970s) has also been a success, where 114 out of 166 breeding pairs by 2007 were successful producing altogether 182 fledged young. Wintering Hungarian population may now reach about a thousand eagles. In
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
, back in 1985 no pairs were known to have bred but established pairs numbered 90 by 2007 and swelled to 120 by 2011.Dementavičius, D. (2007). ''White-tailed Eagle (''Haliaeetus albicilla'') in Lithuania: population numbers and trends 1900–2007''. Acta Zoologica Lituanica, 17(4), 281–285. On 22 May 2006, it was announced that a pair of white-tailed eagles breeding in the Oostvaardersplassen nature reserve in the Netherlands had arrived on their own, not as a reintroduction. This was the first time the bird has bred in the Netherlands in living memory. In 2007, 2008 and 2009 the eagles returned to their nest. The Dutch national forestry, which owns the reserve, installed a webcam trained on the nesting eagles. In 2010, it turned out that the white-tailed eagle was also breeding in the Zwarte Meer nature district and in the Lauwersmeer area. There is also a confirmed case of breeding white-tailed eagles in the Biesbosch. Currently (2017), there are around ten pairs breeding spread over Dutch country. Studies of
microsatellite A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. ...
and
mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
in white-tailed eagles from north-central Europe have shown that the recovering European population has retained appreciable amounts of
genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. It is dis ...
, implying low risk of
inbreeding depression Inbreeding depression is the reduced biological fitness which has the potential to result from inbreeding (the breeding of related individuals). Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. ...
(a serious concern in species with low
population density Population density (in agriculture: standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geographical term.Matt RosenberPopu ...
). Therefore, recovery of this formerly endangered species is a true success story for nature conservation. The story also shows how local protection of a species can be successful and important for preserving the species' evolutionary potential. As of 2013, the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
estimated the total population of mature breeding white-tailed eagles at 20,000–49,999 individuals.


Heraldry

White-tailed eagle are prominent in ancient Saxon folklore and artwork with many landmarks named after the species. It is believed to be the White eagle shown in the German Coat of arms, Polish coat of arms and in the Serbian coat of arms. The sea eagle is often blazoned grasping a fish (usually a pike) in its talons, distinguishing it from an ordinary eagle.


Prehistory

On
Orkney Orkney (; sco, Orkney; on, Orkneyjar; nrn, Orknøjar), also known as the Orkney Islands, is an archipelago in the Northern Isles of Scotland, situated off the north coast of the island of Great Britain. Orkney is 10 miles (16 km) north ...
, Scotland, sea eagle bones have been found in 6,000-year-old burial mounds, among them the Tomb of the Eagles, suggesting that the birds were revered by the prehistoric people there, a belief strengthened by the Pictish stone carvings of sea eagles from Orkney. Cut marks have been found in white-tailed eagle talons in
Krapina Krapina (; hu, Korpona) is a town in northern Croatia and the administrative centre of Krapina-Zagorje County with a population of 4,482 (2011) and a total municipality population of 12,480 (2011). Krapina is located in the hilly Zagorje reg ...
, suggesting
Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an Extinction, extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ag ...
s' use of
jewellery Jewellery ( UK) or jewelry ( U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a w ...
.


Folklore

In the Shetland Isles, Scotland, fishermen believed that as soon as a sea eagle appeared fish would rise to the surface, belly up; this led to some fishermen using eagle fat, smeared on their bait, to increase their catch.


References


Citations


Cited works

* * * * * * * * . The authors' reservations about using the generalised "2%" rate of
molecular evolution Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genet ...
have since proven to be well founded.


Further reading

; Identification * ; Extinction in Scotland * *


External links


White-tailed Eagle Webcam - Smøla, Norway

White-tailed Eagle
at RSPB: Birds by Name
Live webcam nest White-tailed Eagle, Oostvaardersplassen, Netherlands

Fieldguide page on Flickr

White-tailed Eagles in Scotland
BBC website. * * * * *

{{Authority control Haliaeetus, white-tailed eagle Articles containing video clips Birds of prey of Eurasia Birds of Russia white-tailed eagle white-tailed eagle