View source for White-tailed eagle

{{Short description|Species of bird}}
{{Use dmy dates|date=January 2022}}
{{Use Oxford spelling|date=August 2024}}
{{Speciesbox
| image = White tailed eagle raftsund square crop.jpg
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=BirdLife International |date=2020 |title=''Haliaeetus albicilla'' |volume=2020 |page=e.T22695137A181768148 |doi=10.2305/IUCN.UK.2020-3.RLTS.T22695137A181768148.en |access-date=19 November 2021}}</ref>
| status2 = CITES_A1 
 | status2_system = CITES 
 | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus = Haliaeetus
| species = albicilla
| authority = ([[Carl Linnaeus|Linnaeus]], 1758)
| subdivision_ranks = Subspecies
| subdivision_ref = <ref>Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.</ref>
| subdivision =
* ''H. a. albicilla'' - (Linnaeus, 1758)
* ''H. a. groenlandicus'' - Brehm, CL, 1831
| range_map = HaliaeetusAlbicillaIUCN.svg
| range_map_caption = Range of ''H. albicilla''
{{leftlegend|#00FF00|Breeding|outline=gray}} {{leftlegend|#008000|Resident|outline=gray}} {{leftlegend|#00FFFF|Passage|outline=gray}}
{{leftlegend|#007FFF|Non-breeding|outline=gray}} 
{{leftlegend|#FFFF00|Extant & Reintroduced (resident)|outline=gray}}  {{leftlegend|#a76f3b|Extant & Reintroduced (passage)|outline=gray}} 
| synonyms =
''Falco albicilla'' {{small|Linnaeus,&nbsp;1758}}<br />
''Falco melanaetos'' {{small|Linnaeus,&nbsp;1766}}<br />
''Falco ossifragus'' {{small|Linnaeus,&nbsp;1766}}<br />
''Haliaeetus albicilla albicilla''<br />
''Haliaeetus albicilla groenlandicus''
}}

The '''white-tailed eagle''' ('''''Haliaeetus albicilla'''''), sometimes known as the '[[sea eagle]]',<ref>{{Cite web|url=https://www.wildlifetrusts.org/wildlife-explorer/birds/birds-prey/white-tailed-eagle|title=White-tailed eagle &#124; The Wildlife Trusts|website=www.wildlifetrusts.org}}</ref> is a large bird of prey, widely distributed across temperate [[Palearctic|Eurasia]]. Like all eagles, it is a member of the family [[Accipitridae]] (or accipitrids) which also includes other diurnal [[Raptor (bird)|raptor]]s such as [[hawk]]s, [[kite (bird)|kite]]s, and [[harrier (bird)|harrier]]s. One of up to eleven members in the genus ''[[Sea eagle|Haliaeetus]]'', which are commonly called sea eagles, it is also referred to as the '''white-tailed sea-eagle'''.<ref name="Helander">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.</ref> Sometimes, it is known as the '''ern''' or '''erne''' (depending on spelling by sources),<ref name="Love-1983">Love, J. A. (1983). ''The return of the Sea Eagle''. Cambridge University Press, {{ISBN|0-521-25513-9}}.</ref> '''gray sea eagle'''<ref>{{cite journal |last=Amadon |first=Dean |author-link=Dean Amadon |year=1963 |title=Comparison of fossil and recent species: some difficulties |journal=The Condor |volume=65 |issue=5 |pages=407–409 |doi=10.2307/1365146 |jstor=1365146 |s2cid=73710353}}</ref> and '''Eurasian sea eagle'''.<ref>Ridgway, R., & Friedmann, H. (1919). ''The birds of North and Middle America: a descriptive catalogue of the higher groups, genera, species, and subspecies of birds known to occur in North America, from the Arctic lands to the Isthmus of Panama, the West Indies and other islands of the Caribbean sea, and the Galapagos Archipelago'' (Vol. 50, No. 8). Govt. Print. Off.</ref>

While found across a wide range, today breeding from as far west as [[Greenland]] and [[Iceland]] across to as far east as [[Hokkaido]], [[Japan]], they are often scarce and spottily distributed as a nesting species, mainly due to human activities. These have included [[Habitat fragmentation|habitat alterations]] and destruction of [[wetland]]s, about a hundred years of systematic persecution by humans (from the early 1800s to around [[World War II]]) followed by inadvertent poisonings and epidemics of nesting failures due to various manmade chemical [[pesticide]]s and [[organic compound]]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.<ref name="Love-1983"/><ref>King, W. B., & Vincent, J. (1978). ''Endangered birds of the world, The ICBP Bird red data book (Vol. 2)''. Smithsonian Inst Press.</ref><ref name="Hailer">{{cite journal |last1=Hailer |first1=Frank |last2=Gautschi |first2=Barbara |last3=Helander |first3=Björn |year=2005 |title=Development and multiplex PCR amplification of novel microsatellite markers in the White-tailed Sea Eagle, ''Haliaeetus albicilla'' (Aves: Falconiformes, Accipitridae) |journal=Molecular Ecology Resources |volume=5 |issue=4 |pages=938–940 |doi=10.1111/j.1471-8286.2005.01122.x}}</ref><ref name="Krone">{{cite journal |last1=Krone |first1=Oliver |last2=Stjernberg |first2=Torsten |last3=Kenntn |first3=Norbert |last4=Tataruch |first4=Frieda |last5=Koivusaari |first5=Juhani |last6=Nuuja |first6=Ismo |display-authors=1 |year=2006 |title=Mortality factors, helminth burden, and contaminant residues in white-tailed sea eagles (Haliaeetus albicilla) from Finland |journal=Ambio: A Journal of the Human Environment |volume=35 |issue=3 |pages=98–104 |doi=10.1579/0044-7447(2006)35[98:MFHBAC]2.0.CO;2 |pmid=16846196 |s2cid=34897657}}</ref> Some populations have since recovered well, due to governmental protections, dedicated [[Conservation movement|conservationists]] and naturalists protecting habitats and nesting sites, partially regulating poaching and pesticide usage, as well as careful [[Species reintroduction|reintroductions]] into parts of their former range.<ref name="Ferguson-Lees">{{cite book |last1=Ferguson-Lees |first1=James |last2=Christie |first2=David A. |year=2001 |others=Illustrated by Kim Franklin, David Mead, and Philip Burton |title=''Raptors of the World'' |publisher=Houghton Mifflin |isbn=978-0-618-12762-7 |url=https://books.google.com/books?id=hlIztc05HTQC&pg=PP1 |access-date=29 May 2011}}</ref><ref name="Krüger">{{cite journal |last1=Krüger |first1=Oliver |last2=Grünkorn |first2=Thomas |last3=Struwe-Juhl |first3=Bernd |year=2010 |title=The return of the White-tailed Eagle (Haliaeetus albicilla) to northern Germany: modelling the past to predict the future |journal=Biological Conservation |volume=143 |issue=3 |pages=710–721 |doi=10.1016/j.biocon.2009.12.010}}</ref><ref name="Love-1988">Love, J. A. (1988). ''The reintroduction of the white-tailed sea eagle to Scotland: 1975–1987''. Nature Conservancy Council.</ref>

White-tailed eagles usually live most of the year near large bodies of open water, including [[Coast|coastal saltwater areas]] and inland [[freshwater]] [[lake]]s, wetlands, [[bog]]s and [[river]]s. It requires [[Old-growth forest|old-growth trees]] or ample sea cliffs for nesting,<ref name="Love-1983"/><ref name="Ferguson-Lees"/> and an abundant food supply of [[fish]] and [[bird]]s (largely [[water bird]]s) amongst nearly any other available prey.<ref name="Love-1983"/><ref name="Ferguson-Lees"/>  Both a powerful [[apex predator]] and an opportunistic [[scavenger]], it forms a [[Species complex|species pair]] with the [[bald eagle]] (''Haliaeetus leucocephalus''), which occupies a similar [[Ecological niche|niche]] in North America.{{sfn|Wink|Heidrich|Fentzloff|1996}}

==Taxonomy==
The first [[Species description|formal description]] of the white-tailed eagle was by the Swedish naturalist [[Carl Linnaeus]] in 1758 in the [[10th edition of Systema Naturae|tenth edition]] of his ''[[Systema Naturae]]'' under the [[binomial nomenclature|binomial name]] ''Falco albicilla''.<ref>{{cite book |last1=Linnaeus |first1=C. |author-link=Carl Linnaeus |year=1758 |title=Systema Naturæ per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Volume 1 |volume=1 |edition=10th |page=89 |publisher=Holmiae:Laurentii Salvii |language=la |url=https://www.biodiversitylibrary.org/page/726996 }}</ref><ref>{{cite book |editor1-last=Mayr |editor1-first=Ernst |editor1-link=Ernst Mayr |editor2-last=Cottrell |editor2-first=G. William |year=1979 |title=Check-list of Birds of the World. Volume 1 |volume=1 |edition=2nd |publisher=Museum of Comparative Zoology |place=Cambridge, Massachusetts |page=301 |url=https://www.biodiversitylibrary.org/page/16108941}}</ref> The [[genus]] ''[[Haliaeetus]]'' was introduced in 1809 by the French naturalist [[Marie Jules César Savigny]] in the ''[[Description de l'Égypte]]''.<ref>{{cite book |last1=Savigny |first1=Marie Jules César |author-link=Marie Jules César Savigny |year=1809 |title=Description de l'Égypte: Histoire naturelle. Volume 1 |publisher=Imprimerie impériale |place=Paris |language=fr |pages=[https://www.biodiversitylibrary.org/page/15989457 68], [https://www.biodiversitylibrary.org/page/15989474 85]}}</ref> The name ''Haliaeetus'' is [[Neo-Latin]] for "sea-eagle", from [[Ancient Greek]] ''hali-'', "sea-" and ''aetos'', "eagle". The specific ''albicilla'', "white-tailed", is from Neo-Latin ''albi-'', "white" and ''cilla'', "tail".<ref name="Jobling">{{cite book |last1=Jobling |first1=James A. |year=2010 |title=The Helm Dictionary of Scientific Bird Names |url=https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling |publisher=Christopher Helm |location=London |isbn=978-1-4081-2501-4 |pages=[https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling/page/n38 38], 185}}</ref> The [[Anglo-Saxon]] name ''erne'' means "soarer", and it is [[cognate]] to Swedish ''örn'' and Finnish ''aarni''.<ref name="Love-1983" /> It has many Gaelic names, including ''iolar sùil na grèine'' or 'eagle of the sun's eye.'{{sfn|The Nature of Scotland|p=49}}

== Systematics ==
[[File:White-tailed Sea-Eagle - Hokkaido - Japan S4E9284 (15437353795).jpg|thumb|Wintering adult white-tailed eagle in [[Hokkaido]], [[Japan]]]]
[[File:White-tailed eagle LGphoto.jpg|thumb|Two adult white-tailed eagles in snow in [[Färnebofjärden National Park]], [[Sweden]]]]
The white-tailed eagle is a member of the genus ''Haliaeetus'', a [[Monophyly|monophylic group]] comprising 11 living species, including the closely related ''Ichthyophaga'' fish eagles which may or may not be part of a separate genus. The latter group, comprising the [[Lesser fish eagle|lesser]] (''Haliaeetus humilis'') and the [[grey-headed fish eagle]] (''Haliaeetus ichthyaetus''), differ mostly in life history, being more fully devoted to fish eating and habituating wooded areas, especially in mountainous areas. In appearance the two ''Ichthyaetus'' are slenderer, longer tailed and more uniform and grey in colour than typical sea eagles. This species pair may not be genetically distinct enough to warrant division into separate genera.<ref name="Seibold">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.</ref><ref name="Griffiths">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.</ref> Other than these ''Ichthyophaga''-type species found farther north in Asia, [[Sanford's sea eagle]] (''Haliaeetus sanfordi'') of the [[Solomon Islands]] is the most atypical ''Haliaeetus'', retaining rufous-brown plumage into adulthood (this particularly resembling the [[white-bellied sea eagle]] juvenile, likely a closely related species) more typical of juveniles in other species and it also dwells more so in dense, coastal forests where it feeds mostly on [[bird]]s and [[mammal]]s rather than [[fish]] and [[water bird]]s.<ref name="Love-1983"/><ref>Olsen, J. (2016). ''Notes on Sanford's Sea-Eagle Haliaeetus sanfordi and Other Raptors in the Solomon Islands''. Australian Field Ornithology, 17(2).</ref> 

Outside of the genus ''Haliaeetus'', among other extant forms, they appear to be most closely related to [[Milvinae|milvine kites]] and [[Old World vulture]]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]] (''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.<ref name="Love-1983"/><ref>Seibold, I., & Helbig, A. J. (1995). ''Evolutionary history of New and Old World vultures inferred from nucleotide sequences of the mitochondrial cytochrome b gene''. Phil. Trans. R. Soc. Lond. B, 350(1332), 163–178.</ref><ref name="Wink2">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.</ref> Other groups, beyond milvine kites and Old World vulture, of modern accipitrids that are seemingly in some way related, albeit distantly, to the sea eagles include ''[[Accipiter]]s'', [[Harrier (bird)|harriers]], [[Melierax|chanting-goshawk]]s and [[Buteoninae|buteonines]]. Notably excluded from their relations are most other species referred to as "eagles", including [[Aquilinae|booted eagles]] and [[Circaetinae|snake and serpent eagles]].<ref name="Ferguson-Lees"/>{{sfn|Wink|Heidrich|Fentzloff|1996}}<ref name="Wink2"/><ref name="Kenward">{{cite book |title=The Goshawk |first1=Robert |last1=Kenward |year=2006 |publisher=T & A D Poyser |location=London, UK |page=274 |isbn=978-0-7136-6565-9 |url=https://books.google.com/books?id=_tGnSRa0S6sC&pg=PA274}}</ref>

The white-tailed eagle itself forms a [[cryptic species complex|species pair]] with the [[bald eagle]]. These diverged from other sea eagles at the beginning of the early [[Miocene]] (c. 10&nbsp;[[mya (unit)|mya]]) at the latest, possibly (if the most ancient fossil record is correctly assigned to this genus) as early as the early or middle [[Oligocene]], about 28&nbsp;[[mya (unit)|mya]].{{sfn|Wink|Heidrich|Fentzloff|1996}} A recent genetic study of [[mitochondrial DNA]]{{sfn|Hailer|Helander|Folkestad|Ganusevich|2007|p=}} is consistent with this idea. Greenlandic white-tailed eagles (proposed as ''H. a. groenlandicus'') form, on [[evolution]]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 colouring and size (i.e. the eastern average slightly darker and smaller than more westerly ones).<ref>Oberholser, H.C. (1921). ''Journal of the Washington Academy of Sciences; Abstract: Ornithology''. Washington Academy of Sciences.</ref> 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 Ocean|Pacific]], spreading westwards into Eurasia and eastwards into [[North America]]. Like the third large northern species, [[Steller's sea eagle]] (''Haliaeetus pelagicus''), adults have yellow feet, beaks and eyes. Another species, likely intermediate between the white-tailed, bald and Steller's sea eagles and the ''Ichthyophaga'' type fish eagles, is the [[Pallas's fish eagle]] (''Haliaeetus leucoryphus''), which in life history seems to range farther from water and to higher elevations than the three northern species normally do. Due to the similar dietary and nesting habits of sea eagles, they are mostly [[Allopatric speciation|allopatric]] in distribution as competition can be considerable between these eagles.<ref name="Love-1983"/><ref name= Seibold/>

Currently, eagles occur in the [[Hawaiian Islands]] only as vagrants, but [[Quaternary]] bones of ''Haliaeetus'' have been found on three of the major islands. An ancient DNA study published in 2015 characterized the rapidly evolving mitochondrial control region of one of these specimens.<ref name=Hailer2015>{{cite journal |first1=Frank |last1=Hailer |first2=Helen F. |last2=James |first3=Storrs L. |last3=Olson |first4=Robert C. |last4=Fleischer |year=2015 |title=Distinct and Extinct: Genetic Differentiation of the Hawaiian Eagle |journal=Molecular Phylogenetics and Evolution |volume=83 |pages=40–43 |doi=10.1016/j.ympev.2014.11.005 |pmid=25463753 |bibcode=2015MolPE..83...40H |url=http://orca.cf.ac.uk/71249/1/Hailer%20et%20al%20%202015%20MPE%20-%20Hawaiian%20eagle%20-%20postprint.pdf}}</ref> [[DNA]] from a ~3,500-year-old sea eagle skeleton found in a lava cave on [[Maui]] was sequenced. Phylogenetic analyses suggested that the Hawaiian eagle represents a distinct (>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.<ref name="Auk117.4.1051">{{cite journal|last1=Fleischer |first1=Robert C. |last2=Olson |first2=Storrs L. |last3=James |first3=Helen F. |last4=Cooper |first4=Alan C. |author2-link=Storrs L. Olson |author3-link=Helen F. James |year=2000 |title=Identification of the Extinct Hawaiian Eagle (''Haliaeetus'') by mtDNA Sequence Analysis |journal=The Auk |volume=117 |issue=4 |pages=1051–1056 |doi=10.1093/auk/117.4.1051|doi-access=free }}</ref>

== Description ==

===Size===
[[File:White tailed eagle.jpg|thumb|upright=0.8|The white-tailed eagle is the largest eagle found in Europe and most of its Asian range.]]
The white-tailed eagle is one of the largest living birds of prey. It is the largest of the dozen species of eagle found in Europe and the largest eagle across its distribution, excluding the [[Russian Far East]] and (during the winter) Hokkaido, Japan, where it co-exists with its larger cousin, Steller's sea eagle. The white-tailed eagle is sometimes considered the fourth largest eagle in the world{{sfn|The Nature of Scotland|p=49}} 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'').<ref name="Ferguson-Lees"/><ref name="HBW">{{cite book |editor-last=del Hoyo |editor-first=J. |editor2-last=Elliott |editor2-first=A. |editor3-last=Sargatal |editor3-first=J. |year=1994 |title=Handbook of the Birds of the World |volume=2 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-15-3 |title-link=Handbook of the Birds of the World}}</ref> The white-tailed eagle measures anywhere from {{convert|66|to|94|cm|in|abbr=on}} in total length with a typical wingspan of {{convert|1.78|to|2.45|m|ftin|0|abbr=on}}.<ref name="Ferguson-Lees"/><ref name="NatlGeog">{{cite book |year=2002 |title=National Geographic Field Guide to the Birds of North America |edition=4th |publisher=National Geographic |location=Washington, D.C. |isbn=978-0792268772}}</ref> This species may have the largest wingspan of any living eagle.<ref name="Ferguson-Lees"/><ref name="HBW"/> 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.<ref name="Ferguson-Lees"/> The white-tailed eagle does appear to outsize the average wingspan of the [[wedge-tailed eagle]] (''Aquila audax''), which is sometimes also titled the largest winged extant eagle due to an exceptionally large individual shot in 1931,<ref name="Wood">{{cite book |last1=Wood |first1=Gerald |title=The Guinness Book of Animal Facts and Feats |year=1983 |publisher=Guinness Superlatives |isbn=978-0-85112-235-9 |url-access=registration |url=https://archive.org/details/guinnessbookofan00wood}}</ref> although the Steller's sea eagle may rival it in that respect. 

In one sample from [[Norway]], five male white-tailed eagles were found to average {{convert|2.26|m|ftin|0|abbr=on}} and eight females were found to average {{convert|2.37|m|ftin|0|abbr=on}}.<ref name="Willgohs">Willgohs, J. F. (1961). ''The white-tailed eagle ''Haliaëtus albicilla albicilla'' (Linné) in Norway''. Norwegian Universities Press.</ref> In another sample of wild birds of unspecified origin, five males were found to average {{convert|2.1|m|ftin|0|abbr=on}} and seven females averaged {{convert|2.3|m|ftin|0|abbr=on}}.<ref name="Brown">{{cite book |last1=Brown |first1=L.H. |last2=Amadon |first2=D. |year=1968 |title=Eagles, hawks and falcons of the world. Volume 1 |publisher=Hamlyn Publishing Group}}</ref> Record wingspans have included a specimen from Greenland which measured {{convert|2.53|m|ftin|0|abbr=on}} while another specimen apparently spanned {{convert|2.6|m|ftin|0|abbr=on}}.<ref name="ravingravens">{{cite web |first1=Hjörtur |last1=Smárason |url=http://www.ravingravens.com/blog/2011/03/worlds-largest-white-tailed-eagle-found-in-greenland.html |title=World's Largest White-tailed Eagle |date=29 March 2011 |access-date=11 October 2011 |archive-url=https://web.archive.org/web/20131203002519/http://www.ravingravens.com/blog/2011/03/worlds-largest-white-tailed-eagle-found-in-greenland.html |archive-date=3 December 2013 |url-status=dead}}</ref><ref>Krone, O., Kenntner, N., Trinogga, A., Nadjafzadeh, M., Scholz, F., Sulawa, J., Totschek, K., Schuck-Wersig, P. & Zieschank, R. (2009). ''Lead poisoning in white-tailed sea eagles: causes and approaches to solutions in Germany''. Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. DOI, 10.</ref> 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 (biology)|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.<ref name="Love-1983"/><ref name="Ferguson-Lees"/><ref name="Friedmann">Friedmann, H. (1950). ''Birds of North and Middle America, Pt. 2''. U.S. Nat. Mus. Bull. no. 50.</ref><ref name="Imler">Imler, R. H., & Kalmbach, E. R. (1955). ''The Bald Eagle and its economic status (Vol. 30)''. US Government Printing Office.</ref>

Size variation is generally a [[Cline (biology)|clinal]] trend and is normally quantified using standard measurements such as wing, tail and tarsal length, or body mass, rather than wingspan or total length. As expected for many widely distributed animals of varied lineages, the white-tailed eagle conforms to [[Bergmann's rule]] in that more northerly birds tend to outsize those found relatively closer to the [[Equator]]. Average size also decreases from west to east across its distribution.<ref name="Love-1983"/>{{sfn|Hailer|Helander|Folkestad|Ganusevich|2007|p=}}<ref name="Zhengjie">Zhengjie, Z. (2001). ''Birds of China, Vol.1 (Non-Sparrow-shaped)'': Jilin Science and Technology Press: 275–276</ref> The largest white-tailed eagles appear to be found in [[Greenland]], these being slightly larger than those from [[Ireland]], [[Scotland]] and [[Scandinavia]] and notably larger than eagles from [[central Europe]], especially in proportions of the wing area. Those from the southerly portions of the breeding range, such as [[Asia Minor]] (principally [[Turkey]]), southern [[Kazakhstan]], and [[Korea Bay]], appear to be the smallest-bodied population but there have been limited measurements and published weights known for these extremely sporadic and rare Asian populations of eagle. Furthermore, weights of fully grown eagles from Greenland are not known.<ref name="Love-1983"/><ref name="Ferguson-Lees"/><ref name="Brown"/> 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.<ref name="Love-1983"/><ref name= Cramp>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.</ref> In the white-tailed eagle, body mass can typically range from {{convert|4|to|6.9|kg|lb|abbr=on}} in females. The slightly smaller male may typically weigh from {{convert|3.1|to|5.4|kg|lb|abbr=on}}.<ref name="Ferguson-Lees"/> 

Average weights in European white-tailed eagles can range from {{convert|4.02|kg|lb|abbr=on}} in five males and {{convert|5.11|kg|lb|abbr=on}} in nine females to (from the reintroduced birds of Scotland of Norwegian stock) {{convert|4.98|kg|lb|abbr=on}} in 39 males and {{convert|6.06|kg|lb|abbr=on}} in 43 females.<ref name="Love-1988"/><ref name="Brown"/> In comparison, the weight ranges for white-tailed eagles from [[Northeast China]] were claimed to be only {{convert|2.8|to|3.78|kg|lb|abbr=on}} in males and {{convert|3.75|to|4.6|kg|lb|abbr=on}} in females.<ref name="Zhengjie"/> The heaviest female white-tailed eagles can apparently weigh as much as {{convert|7.5|to|8|kg|lb|abbr=on}} and even males can sometimes weigh up to {{convert|6.5|kg|lb|abbr=on}}, which would make the largest males perhaps the heaviest recorded modern male eagle, as male harpy and Philippine eagles (being more [[sexually dimorphic]] in favour of the female) are not known to exceed {{convert|5|kg|lb|abbr=on}} (the highest weights for male Steller's sea eagle are not known).<ref name="Love-1983"/><ref name=Wood/><ref name="CRC">''CRC Handbook of Avian Body Masses, 2nd Edition'' by John B. Dunning Jr. (Editor). CRC Press (2008), {{ISBN|978-1-4200-6444-5}}.</ref><ref>Šebík, J. (2013). ''Orel mořský''. Czech Atlas of Oceanic Life.</ref> The global mean body mass of white-tailed eagles is estimated at approximately {{convert|5|kg|lb|abbr=on}}.<ref name="CRC"/><ref name="Nadjafzadeh">{{cite journal |last1=Nadjafzadeh |first1=Mirjam |last2=Voigt |first2=Christian C. |last3=Krone |first3=Oliver |year=2015 |title=Spatial, seasonal and individual variation in the diet of White-tailed Eagles Haliaeetus albicilla assessed using stable isotope ratios |journal=Ibis |volume=158 |issue=1 |pages=1–15 |doi=10.1111/ibi.12311 |s2cid=83836591}}</ref><ref>Sutton, A. E. (2015). ''Leadership and management influences the outcome of wildlife reintroduction programs: findings from the Sea Eagle Recovery Project''. PeerJ, 3, e1012.</ref> 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.<ref name="CRC"/><ref name="Watson">{{cite book |last1=Watson |first1=Jeff |title=The Golden Eagle |url=https://books.google.com/books?id=aj5MNvCkun0C |year=2010 |publisher=A&C Black |isbn=978-1-4081-1420-9}}</ref><ref name="McClelland-1998">{{Cite journal |last1=McClelland |first1=B. Riley |last2=Shea |first2=David S. |last3=McClelland |first3=Patricia T. |last4=Patterson |first4=David A. |title=Size Variation of Migrant Bald Eagles at Glacier National Park, Montana |url=https://sora.unm.edu/sites/default/files/journals/jrr/v032n02/p00120-p00125.pdf |journal=Journal of Raptor Research |volume=32 |issue=2 |pages=120–125 |year=1998 |issn=0892-1016}}</ref>

===Standard measurements and sexual dimorphism===
[[File:Nederlandsche vogelen (KB) - Haliaeetus albicilla (418b).jpg|thumb|upright|An illustration of the large bill and sharply curved talons of a juvenile white-tailed eagle]]
The most reliable method to sex birds is by tarsus width and depth and bill depth but these are infrequently measured.<ref name="Love-1983"/>{{sfn|Helander|Hailer|Vilà|2007}}<ref>Helander, B. (1981). ''Nestling measurements and weights from two White-tailed Eagle populations in Sweden''. Bird Study, 28(3), 235–241.</ref> 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.<ref name="Ferguson-Lees"/> Among standard measurements, the [[Wing chord (biology)|wing chord]] is {{convert|552|to|695|mm|in|abbr=on}} in males, averaging {{convert|606|and|645|mm|in|abbr=on}} in European adults and juveniles, respectively, and {{convert|646.5|mm|in|abbr=on}} in Greenland males.<ref name="Brown"/><ref name="Cramp"/> In females, the wing chord may measure {{convert|605|to|740|mm|in|abbr=on}}, averaging {{convert|668|and|685|mm|in|abbr=on}} in European adults and juveniles, respectively, and {{convert|691.3|mm|in|abbr=on}} in Greenland females.<ref name=Brown/><ref name=Cramp/> Adult [[tail]] length is {{convert|250|to|331|mm|in|abbr=on}} in males, averaging {{convert|280|mm|in|abbr=on}}, and {{convert|276|to|330|mm|in|abbr=on}} in females, averaging {{convert|305|mm|in|abbr=on}}. Juvenile tail lengths can reach roughly {{convert|380|mm|in|abbr=on}} in both sexes, however.<ref name=Cramp/> The [[Tarsus (skeleton)|tarsus]] is {{convert|90|to|101|mm|in|abbr=on}}, averaging {{convert|95.5|mm|in|abbr=on}}.<ref name=Zhengjie/><ref name=Cramp/> 

In terms of their killing apparatuses, their [[Toe|hallux claw]], the largest talon on all accipitrids, is {{convert|37|to|46|mm|in|abbr=on}} in length, averaging {{convert|40.9|mm|in|abbr=on}}.<ref name=Cramp/> The hallux claw averages about a centimeter less than that of a [[golden eagle]] and is more sharply curved, an adaptation to prevent escape of slippery prey such as fish, while that of a bald eagle is similarly about {{convert|40.4|mm|in|abbr=on}} and of similar curvature.<ref name="Bortolotti">{{cite journal |last=Bortolotti |first=Gary R. |year=1984 |title=Age and Sex Size Variation in Golden Eagles |journal=Journal of Field Ornithology | volume=55 |issue=1 |pages=54–66 |url=https://sora.unm.edu/sites/default/files/journals/jfo/v055n01/p0054-p0066.pdf}}</ref><ref name=Zylo>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).</ref> The [[Culmen (bird)|exposed culmen]] is typically large as in all ''Haliaeetus'', ranging from {{convert|45|to|65|mm|in|abbr=on}}, with an average of {{convert|56.1|mm|in|abbr=on}}.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name=Zhengjie/><ref name=Cramp/><ref name=indianbiodiversity>{{cite web |url=http://avis.indianbiodiversity.org/birds/aves/accipitriformes/accipitridae/haliaeetus/haliaeetus-albicilla |title=''Haliaeetus albicilla'' |website=avis.indianbiodiversity.org}}</ref> The average culmen length of the bald eagle is {{convert|54.3|mm|in|abbr=on}}, 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 {{convert|75|mm|in|abbr=on}} and can even rival the length (but perhaps not the girth) of the truly massive bill of the Steller's sea eagle.<ref name=Friedmann/><ref name=Imler/><ref name=Zylo/>

===Colouring and field appearance===
The adult white-tailed eagle is a greyish mid-brown colour overall. The plumage is fairly uniform over most of the body and wings, but the upper wing [[Covert feather|coverts]] are typically somewhat paler. In the adult, the head, neck and upper breast have a distinctly paler appearance than the rest of the plumage and most often have a [[Buff (color)|buff]] colouration. In worn or bleached plumages these light areas can be even paler at times, ranging to almost whitish, which can render a resemblance in such eagles to a washed-out bald eagle. Some of the palest birds can appear anywhere from cream-tawny to light greyish. It is thought that in some populations perhaps paleness increases with age, although it is possible that there is an historical genetic factor to these pale variations. In contrast, some adults can also be a richer, more deeply dark brown (or somewhat [[rufescent]]) than average with perhaps a mild increase in average darkness of hue to the east of the species' range.<ref name="Love-1983"/><ref name=Ferguson-Lees/>{{sfn|Hailer|Helander|Folkestad|Ganusevich|2007|p=}} When many of the feathers are freshly moulted, they can take on a slight purplish gloss.<ref name= Brown/> The brownish hue of the adult overall makes the somewhat wedge-shaped white tail stand out in contrast.<ref name=Ferguson-Lees/> All the bare parts of the adult's body are yellow in colour, including the bill, [[cere]], feet and eyes.<ref name="Love-1983"/> 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 [[Glossary of bird terms#axillaries|axillary]] strip usually apparent.
[[File:Haliaeetus albicilla (Svolvær, 2012).jpg|thumb|Adult eagle from [[Svolvær]], [[Norway]] showing characteristic long, broad, fingered wings, heavy bill and short wedge-shaped tail]]
[[File:White-tailed Eagle 34.jpg|thumb|An example of a darker, more richly coloured adult than average]]
The upperside is usually similarly darkish brown but variable based on extent of blackish-brown tip to otherwise buff-brown feathers of the mantle, back and upper wing. The head of the juvenile is normally a blackish-brown hue, somewhat darker and always more uniform than most of the other feathers. The juvenile's tail tends to be a washed out greyish-cream colour with messy blackish colour on the feather edges and on the tips. Some individual juveniles may exhibit some faint barring on the tail while others may appear largely dirty whitish on the tail. The bill of juveniles is usually almost half dark brown from the tip and half dirty, dull yellowish or grey to the base, while the feet are usually a dirty yellow and the eyes are a darkish brown. Juvenile males may average a slightly darker brown plumage with less speckling on the upper body than like-age females; their head and neck plumes may also appear shorter, which can accentuate the slighter, more angular skull possessed by males. In disposition, the male juveniles are said to be more highly strung and higher voiced than their female counterparts.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name=Brown/> 

The head gradually grows paler over several years. The whitish mottling may increase on the upperparts, belly and especially on the underwing area later into their third year (considered the first subadult plumage) and subadult birds can appear fairly blotched with white but much individual variation in colouring is known at this age. However, this white mottling then fades late into the fourth year and the plumage becomes less contrasting.<ref name="Love-1983"/><ref name=Ferguson-Lees/> 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.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name=Brown/> Juveniles first moult in May/June until October/November at just over one year of age. Their second moult is the following year in March or April, with two more subsequent moults usually beginning around this time for the next couple of years. Like other large raptors, feathers are moulted at slow intervals so as not to inhibit food capture. Only relatively small proportions of the flight feathers are moulted each year. Moulting occurs more or less continuously, although it may pause in winter if food is in short supply.<ref>''RSPB Handbook of British Birds'' (2014). UK {{ISBN|978-1-4729-0647-2}}.</ref>

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 (genus)|''Aquila'' eagles]].<ref name=Ferguson-Lees/><ref name="Forsman">Forsman, D. (1999). ''The raptors of Europe and the Middle East: a handbook of field identification''. London: T & AD Poyser.</ref> The neck is at times unusually long-looking, more so than in the bald eagle, which can give the upper body a vulturine appearance. The tail is relatively short, and in some adults it can appear disproportionately stubby in relation to the massive body, and slightly wedge-shaped. All ages have a well-feathered [[tibia]] but bare [[Tarsometatarsus|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 [[Flight feather#Secondaries|secondaries]]. The species tends to fly with shallow wing beats; at times the wing beats can be fairly fast for a bird of this size, but interspersed at times with gliding. At a great distance, this flight style may be suggestive of a large brown [[heron]]. The wings are held flat or slightly upraised at the tip in flight and the white-tailed eagle is well known to soar extensively. This species can be surprisingly maneuverable on the wing, usually during aerial displays or dogfights with other birds. These eagles may also maneuver by half-closing both wings or fully closing one wing.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name=Porter>Porter, R. F. (1981). ''Flight identification of European raptors''. A&C Black.</ref>

===Vocalizations===
The white-tailed eagle is considered a vocal bird of prey during the breeding season, although some authors consider their voice "not loud or impressive for the size of the bird".<ref name=Ferguson-Lees/><ref name=Brown/> The male call is oft transcribed as ''{{not a typo|gri-gri-gri}}'' or ''{{not a typo|krick-krick-krick}}'', while the female is a deeper ''{{not a typo|gra-gra-gra-gra}}'' or ''{{not a typo|krau-krau-krau-krau}}''. These will increase in tempo and pitch, with about 15–30 calls in a sequence. Often pairs will duet during early spring, in flight or from a perch. When perched, the male calls ''{{not a typo|kyi-kyi-kyi-kli-kliek-yak}}'' with the head thrown back and upwards in the last call ended with a lower ''ko-ko-ko'', the perched call of females is similar but deeper, a ''{{not a typo|krau-krau-krau-uik-ik}}''. Typically, the perched version of their calls tend to be shriller and higher than those issued in flight.<ref name=Ferguson-Lees/><ref name=Brown/> 

In courtship display, male calls ''{{not a typo|krau-krau-krau-uik-ik-ik}}'' answered by females with a lower ''{{not a typo|ra-rack-rack-rack-rack}}''. Young in nest call a shrilly ''{{not a typo|piieh-piieh}}'', while the female when receiving food from male calls out with ''{{not a typo|tschie-tschie}}'' or ''{{not a typo|vueee-vueee}}''. Single or repeated ''{{not a typo|krlee}}'' or similar component of calls used in other circumstances, can be variable. Alarm calls tend to be 3–4 short, loud ''{{not a typo|klee}}'' or ''{{not a typo|klek}}'' notes. Sometimes a different call of alarm or anger, a deep ''{{not a typo|gah-gah-gah}}'' or ''{{not a typo|jok-jok-jok}}'', similar to alarm calls of a large [[gull]], is also uttered when a nest is approached (usually recorded while directed towards humans). The young let out a monotonous ''{{not a typo|veee-veee}}'' when hungry (or "bored") which intensifies if the eaglets are not fed or brooded immediately.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name=Brown/><ref name=Mecionis>Mecionis, R., & Jusys, V. (1994). ''The White-Tailed Eagle ''Haliaeetus albicilla'' at Kursiu Lagoon''. Acta Orn. Lituanica, pp. 9–10.</ref>

===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 different in all other respects of plumage.<ref name=Ferguson-Lees/> Even in poor light, the bald species shows a sharp demarcation from white to dark brown whereas the colour contrast is far subtler in white-tailed eagles between their brown body (of a paler hue than that of a bald eagle) and buff-coloured head. At a great distance, the adult may be potentially confusable with the [[Griffon vulture]] (''Gys fulvus''), as the colouring of the two species is vaguely similar and they can overlap somewhat in size although the vulture can average rather heavier and longer winged. However even at long range, the relatively tiny head, distinctly curved trailing wing-edges and more raised wings make the vulture distinctive from the white-tailed eagle.<ref name= Ferguson-Lees/><ref name= Porter/>
[[File:White tailed eagle raftsund juvenile.jpg|left|thumb|upright|A typical white tailed eagle juvenile]]
[[File:Immature white-tailed eagle plumage.jpg|left|thumb|upright|Plumage of an immature white-tailed eagle]]
Juveniles may be harder to distinguish, mainly from other sea eagles in few areas of overlap. In northern [[Mongolia]] (perhaps spilling over into southern [[Siberia]]), the northern part of the [[Caspian Sea]] and some central and southern parts of Kazakhstan, the white-tailed eagle may (or may not) live alongside the rarer, relatively poorly-known [[Pallas's fish eagle]].<ref name="Love-1983"/><ref>BirdLife International (2001). ''Threatened birds of Asia: the BirdLife International Red Data Book'' . Cambridge, UK : BirdLife International.</ref><ref>Gilbert, M., Tingay, R., Losolmaa, J., Sureda, N., Gilbert, C., Batmunkh, D., & Gombobaatar, S. (2014). ''Distribution and status of the Pallas’s Fish Eagle Haliaeetus leucoryphus in Mongolia: a cause for conservation concern?'' Bird Conservation International, 24(3), 379–388.</ref> 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.<ref name=Ferguson-Lees/><ref>MacKinnon, J. R., MacKinnon, J., Phillipps, K., & He, F. Q. (2000). ''A field guide to the birds of China''. Oxford University Press.</ref> Bald eagle juveniles may be found together with white-tailed eagles in the [[Aleutian islands]] (where the white-tailed eagle formerly bred until about 30 years ago) and when vagrants of white-tails occur in Alaska. Juveniles of bald and white-tailed eagles often strongly resemble each other but the bald eagles have a shorter neck, a relatively longer and squarer tail, and somewhat less broad wings. In the colouring, the bald juvenile is similarly as dark or even darker brown above as white-tailed eagle juveniles but on the underside often has more extensive whitish mottling, especially on the underwing.<ref name=Ferguson-Lees/><ref name=Howell>Howell, S. N., Lewington, I., & Russell, W. (2014). ''Rare Birds of North America''. Princeton University Press.</ref>

Steller's sea eagles are usually distinctly larger and longer tailed, with a taller, bulkier look in eagles standing on the ground or perched. Steller's juveniles have a different wing shape (roughly paddle-shaped) and a considerably more massive and paler bill, which is yellow even in juveniles unlike in bald and white-tailed eagles. Juvenile Steller's sea eagles are a distinctly darker soot colour than juvenile white-tailed eagles with even less whitish showing on the body than the latter species but, on the other hand, the underwing often as white marked as juvenile bald eagles (dissimilarly from juvenile white-tailed eagles), albeit in different pattern. In all three large northern sea eagles, the tail colour is similar at the various stages of development but the shape is more distinctive, especially the bolder wedge shape of the Steller's.<ref name= Ferguson-Lees/><ref name= Howell/>

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 (genus)|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 eagle]]s (''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.<ref name=Ferguson-Lees/><ref name=Forsman/> 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 (genus)|Clanga]]'' and ''[[Aquila (genus)|Aquila]]'', both greater spotted and eastern imperial eagles should be obviously distinct from white-tailed eagles by plumage characteristics.<ref name=Forsman/><ref name=Clark>Clark, W. S. (1999). ''A field guide to the raptors of Europe, the Middle East, and North Africa''. Oxford University Press, USA.</ref><ref name=Naoroji>Naoroji, R., & Schmitt, N. J. (2007). ''Birds of prey of the Indian subcontinent''. Om Books International.</ref> 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.<ref name="Love-1983"/>

== Distribution and habitat ==
[[File:White Tailed Eagle AdF.jpg|thumb|Closeup of white-tailed eagle calling]]
[[File:Haliaeetus albicilla -Littleisland, Norway -adult-8a.jpg|thumb|An adult eagle at the [[Littleisland lighthouse]] in Norway]]
[[File:Haliaeetus albicilla -Littleisland, Norway -juvenile-8a (1).jpg|thumb|A young eagle above its nest at [[Littleisland lighthouse]]]]

===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<ref name=DOFNorthGL>{{cite web |title=Havørnen har kurs mod Nordgrønland |url=https://www.dof.dk/om-dof/nyheder?nyhed_id=539 |publisher=[[Dansk Ornitologisk Forening]] |date=11 September 2008 |access-date=18 December 2019}}</ref>), northern and western [[Iceland]], and the reintroduced populations in some areas of [[England]] (re-established in 2019<ref name=Guardian>{{Cite web |url=https://www.theguardian.com/environment/2019/aug/22/white-tailed-eagles-southern-britain |title=White-tailed eagles return to southern Britain after 240 years |first1=Patrick |last1=Barkham |date=22 August 2019 |access-date=23 May 2020 |work=The Guardian}}</ref>), [[Ireland]] and Scotland, particularly conserved coastal spots. In mainland Europe the range is expanding, with Europe's largest population breeding in coastal Norway (broadly),<ref>{{cite web |url=https://magazine.scienceconnected.org/2021/08/norwegian-sea-eagles/ |title=Norwegian Sea Eagles |date=4 August 2021}}</ref> northern and southwestern [[Finland]],<ref name=Stjernberg>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.</ref> eastern [[Sweden]], broadly in [[Denmark]],<ref name=Ehmsen>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.</ref><ref name="DR 2022"/> islands of the [[Baltic Sea]], western [[Austria]], northeastern [[Germany]], northern and eastern [[Poland]],<ref name=Bogucki>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).</ref> the Czech Republic, much of the [[Baltic states|east Baltic countries]], the non-montane areas of [[Ukraine]], eastern [[Slovenia]], central and southern [[Hungary]] (and adjacent northeastern [[Croatia]]), sporadically in [[Greece]],<ref>Vagliano, C. 1977. ''The status of birds of prey in Greece''. Pages 118–125 in RD Chancellor [ED.], World conference on birds of prey, Report of Proceedings, International Council for Bird Preservation.</ref> the [[Danube river|Danube sections]] of [[Romania]] and [[Bulgaria]] to the [[Black Sea]]<ref>Puscariu, V., & Filipascu, A. (1975). ''The situation of Birds of Prey in Rumania in 1970–1974''. In World conf. Birds of Prey. Vienna (pp. 148–152).</ref> and western and eastern [[Moldova]].<ref name="iucn status 19 November 2021" /><ref name=Ferguson-Lees/><ref name=Helander/><ref name=Bijleveld>Bijleveld, M. F. (1974). ''Birds of prey in Europe''. Macmillan.</ref> The bird returned to the [[Netherlands]] in 2006 and in 2020 the number of breeding pairs had increased to 20.<ref>{{Cite web |url=https://www.sovon.nl/nl/actueel/nieuws/toename-zeearenden-nederland |title=Toename Zeearenden in Nederland &#124; Sovon.nl |website=sovon.nl |access-date=23 May 2020}}</ref> It might have bred in the [[Faroe Islands]] up until the 17th century, but evidence is lacking; there are only about a dozen records of vagrant white-tailed eagles from the archipelago since 1800.<ref>{{cite web| title=Liste over Færøernes fugle | url=https://www.dof.dk/images/udvalg/su/dokumenter/su_rapporter/Faeroliste_udg._16a.pdf | publisher=Dansk Ornitologisk Forening | access-date=31 July 2023 }}</ref>

In [[Anatolia]], it only remains as a breeder in sparse and small pockets of Turkey and [[Georgia (country)|Georgia]], taken as a region there are likely to be fewer than 30 breeding pairs in this region.<ref name="iucn status 19 November 2021" /><ref name=Ferguson-Lees/> In the [[Middle East]], the white-tailed eagle may still be found breeding only along the southern coast of the Caspian Sea in northern [[Iran]] and southwestern [[Turkmenistan]].<ref name="iucn status 19 November 2021" /><ref name=Firouz>Firouz, E. (2005). ''The complete fauna of Iran''. IB Tauris.</ref> Discontinuously, they are found as residents in Kazakhstan where they live in a long strip of the southern part of the country starting at the [[Aral Sea]] and the northwestern portion (but not, as far as is known, breeding in the Kazakh part of the Caspian Sea coast).<ref name="iucn status 19 November 2021" /><ref name=Ferguson-Lees/> The only country in which the white-tailed eagle is found over a continuous and extremely large area is [[Russia]]. The species is found broadly everywhere in Russia from [[European Russia]] in the west to the [[Bering Sea]] in the east, only being fully absent as a nester as far as is known from the high Arctic regions and a section bordering westernmost Kazakhstan, although it breeds to south of this in the Russian coastal part of the Caspian Sea.<ref name="iucn status 19 November 2021" /><ref name=Ferguson-Lees/><ref name=Knystautas>Knystautas, A. (1993). ''Birds of Russia''. HarperCollins.</ref> Their northern limits occur in Russia to the [[Ob river]] to 70 degrees north at the mouth of the [[Yenisei River]] and on the [[Gyda Peninsula|Gyda]] and [[Yamal Peninsula]]s, to the [[Kolyma River|Kolyma]], [[Indigirka river|Indigirka]] and [[Lena river]]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]], 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.<ref name="Love-1983"/><ref name=Knystautas/><ref name=Flerov>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.</ref> From Russia, breeding populations spill somewhat into northernmost Mongolia, extreme northwestern [[China]] and northern [[North Korea]]. The white-tailed eagle also breeds on [[Sakhalin Island]], the [[Kuril Islands]] and Hokkaido, the northernmost island of Japan.<ref name="iucn status 19 November 2021" /><ref name=Ferguson-Lees/>

===Wintering range===
[[File:Zittende en vliegende zeearenden van verschillende leeftijden-4961975.webm|thumb|left|Various wintering white-tailed eagles in the [[Netherlands]]]]
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 [[Moselle (department)|Etang de Lindre]] of [[Lorraine]], [[France]] as well as an area on the border of France to Germany around [[Strasbourg]], with vagrants to elsewhere in France, as well as to [[Spain]], [[Portugal]] and [[Malta]].<ref name="Love-1983"/><ref name= Bijleveld/><ref name= Helander/><ref name= Bent>Bent, A. C. (1937). ''Life histories of North American birds of prey''. US Government Printing Office.</ref> A well-defined wintering population may occur in much of the Netherlands, even with infrequent modern breeding in the northern coastal areas.<ref name= Rijn>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.</ref> A wintering population is known in western Germany from [[North Rhine-Westphalia]] to [[Bonn]], as well as far northern Germany.<ref name="iucn status 19 November 2021" /><ref name= Helander/> In Denmark, they both breed and winter throughout much of the country, but in particular the [[Wadden Sea National Park, Denmark|Wadden Sea]] region attracts many white-tailed eagles, mostly immatures, from elsewhere in Denmark and neighbouring countries during the winter.<ref>{{cite web | title=Havørn | url=https://dofbasen.dk/danmarksfugle/art/02430 | publisher=[[Dansk Ornitologisk Forening]] | access-date=30 July 2023 }}</ref><ref name=DOF17Aug2021>{{cite web | title=Ny viden om havørne: Kollektive om vinteren, solister om sommeren | url=https://www.dof.dk/om-dof/nyheder?nyhed_id=1993 | date=17 August 2021 | publisher=[[Dansk Ornitologisk Forening]] | access-date=30 July 2023 }}</ref><ref name="JV-2023">{{cite news | title=Havørnen er flyvende: Aldrig før har der været så mange i Vadehavs-området som nu: Læs her, hvor du kan se dem | url=https://jv.dk/toender/havoernen-er-flyvende-aldrig-foer-har-der-vaeret-saa-mange-i-vadehavs-omraadet-som-nu-laes-her-hvor-du-kan-se-dem | date=1 January 2023 | publisher=JydskeVestkysten | access-date=30 July 2023}}</ref> Other established wintering areas are known in Europe in west-central [[Italy]], northern Austria, fairly broadly in southern [[Slovakia]] and northern Hungary and a few protected pockets of [[Southeast Europe]] apart from the portions in the north and east where they still breed.<ref name="iucn status 19 November 2021" /><ref name= Helander/> 

Intermittent forms of vagrancy and migration (most from eagles that breed in or disperse from Russia) are known to occur in several areas of Turkey, the [[Levant]] countries, [[Azerbaijan]] and Iran down to even the [[Persian Gulf]], albeit seldom is the species to be found commonly or reliably anywhere in these regions. Further east, rare wintering areas are known in a few small, scarce pockets of Turkmenistan, [[Afghanistan]], [[Uzbekistan]], [[Tajikistan]] and [[Pakistan]].<ref name="iucn status 19 November 2021" /><ref name= Ferguson-Lees/><ref name= Firouz/> It is a rare winter visitor to [[India]], namely the extreme northwest and along the border of [[Nepal]] to [[Bhutan]] and extreme northern [[Bangladesh]].<ref>{{Cite book |title=Birds of South Asia. The Ripley Guide |last1=Rasmussen & Anderton |first1=P.C. & J.C. |publisher=Smithsonian Institution and Lynx Edicions |year=2005 |location=Washington, D.C. and Barcelona. |pages=87}}</ref><ref>{{Cite journal |last1=Khan |first1=Asif N. |date=1 August 2015 |title=Sighting of a Juvenile White-Tailed Eagle at Jor Beed Carcass Dump, Bikaner, Rajasthan, India |url=http://www.bnhsjournal.org/index.php/bnhs/article/view/104934 |journal=Journal of the Bombay Natural History Society |language=en |volume=112 |issue=2 |pages=92–93 |doi=10.17087/jbnhs/2015/v112i2/104934 |issn=0006-6982 |doi-access=free}}</ref> Scattered pockets of wintering birds are known to occur too in [[Central China|central]] and [[South China|southern China]], into northeastern [[Myanmar]], and more broadly and regularly in much of Northeast China.<ref>Mackinnon, J., & Hicks, N. (2017). ''Birds of China''. Bloomsbury Publishing.</ref><ref name=Brazil>Brazil, M. (2009). ''Birds of East Asia: China, Taiwan, Korea, Japan, and Russia''. A&C Black.</ref> Good numbers winter too in much of [[South Korea]] and Japan down to as far as [[Honshu]].<ref name="iucn status 19 November 2021" /><ref name=Brazil/> White-tailed eagles dispersing from their breeding grounds or natal sites in the Russian Far East are known to occasionally disperse across the Bering Sea to North America in several parts of the [[Aleutian Islands]], the [[Pribilof Islands]] and some of mainland coastal [[Alaska]] down to [[Kodiak Island]].<ref name=Howell/><ref>Murie, O. J. (1959). ''Fauna of the Aleutian Islands and Alaska peninsula''. North American Fauna, pp. 1–364.</ref> Some white-tailed eagles even bred in [[Alaska]] on [[Attu Island]] in the late 1970s to the early 1980s (until 1984 when the last attempts were recorded) but it was not clear whether young were ever successfully fledged.<ref>Tobish Jr, T. G., & Balch, L. G. (1987). ''First North American nesting and occurrence of ''Haliaeetus albicilla'' on Attu Island, Alaska''. The Condor, 89(2), 433–434.</ref>

===Habitat===
[[File:Noor merikotkas puul..jpg|thumb|right|White-tailed eagles are fairly associated with wooded areas but usually ones quite near water.]]
White-tailed eagles may be found in varied habitat but usually are closely associated with water and generally occurs in lowland areas.<ref name=Ferguson-Lees/> Although mainly a lowland species, the species is known to live at elevations of {{convert|1500|to|2300|m|ft|abbr=on}} so long as there is water access in some parts of [[Central Asia]] and [[Siberia]].<ref name=Brown/> In coastal areas, the species may range from high sea [[cliff]]s down to low-lying [[island]]s and [[archipelago]]s. Especially in winter, many white-tailed eagles often frequent low coastal spots, [[Estuary|estuaries]] and [[Saltmarsh|coastal marshes]]. Several studies have supported that coastal areas are preferred when available during winter.<ref name=Ferguson-Lees/><ref name=Helander/><ref name=Treinys>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.</ref> In many areas, white-tailed eagles can seem to switch freely between usually cliff habitat and [[Woodland|wooded spots]] for nesting sites and the center of their home range habitat.<ref name=Evans>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.</ref> In some areas, such as Japan, this species may occur in regions with intensive human [[fishing]] activity and they may become unusually partially habituated to this human presence.<ref name=Ferguson-Lees/><ref name=Tingay>Tingay, R. E., & Katzner, T. E. (Eds.). (2010). ''The eagle watchers: Observing and conserving raptors around the world''. Cornell University Press.</ref> Inland, white-tailed eagles usually require secluded woods, forested areas or groups of trees with tall [[Old growth forest|mature trees]] and access to freshwater [[wetland]]s such as [[lake]]s, [[River|river systems]], [[marsh]]es or extensive, [[Agricultural land|low-disturbance farmland]].<ref name=Ferguson-Lees/> In the [[Alluvium|alluvial wetlands]] of Croatia, 95% of nests were found within {{convert|4|km|mi|abbr=on}} of deep freshwater.<ref name="Radović-2009">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.</ref>

In some areas, white-tailed eagles readily visit [[Commercial fishing|commercial fish farms]], [[Koi pond|carp ponds]] and similar areas with easily accessible food but they will usually avoid areas where human disturbances (especially noisy varieties such as [[construction]], [[List of water sports|water sporting]] and heavy [[boating]] activities and [[hunting]]) commonly occur.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name=Helander/> However, forestry activity and resulting lessened numbers of tall mature trees and large tree stands in [[Estonia]] was found to affect breeding white-tailed eagles less so than it seemed to affect breeding [[black stork]]s (''Ciconia nigra'').<ref name=Rosenvald>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.</ref> 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.<ref name=Rijn/> 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,<ref name="DOF 2022"/> and they can also successfully breed in such locations.<ref>{{cite news |title=Havørne-par har igen i år fået unger |url=https://voresbrabrand.dk/havoerne-par-har-igen-i-aar-faaet-unger/ |publisher=VoresBrabrand |date=6 June 2018 |access-date=15 June 2022}}</ref><ref>{{cite web |title=Havørne har ynglet med udsigt til København |url=https://www.dof.dk/om-dof/nyheder?nyhed_id=1682 |publisher=[[Dansk Ornitologisk Forening]] |date=19 October 2018 |access-date=15 June 2022}}</ref>

== Behaviour ==
[[File:NuukSeaEagle.ogv|thumb|Greenland eagle]]
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.<ref name="Love-1983"/><ref name=Brown/> 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.<ref name=Brown/>

===Migration and dispersal===
The white-tailed eagle may be considered a rather inconsistent and partial migrant.<ref name="Love-1983"/><ref>Sutherland, W. J. (1998). ''Evidence for flexibility and constraint in migration systems''. Journal of Avian biology, pp. 441–446.</ref> 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.<ref name=Ferguson-Lees/><ref name=Brown/> Few Norwegian juveniles, per banding studies, were recorded to travel any considerable distance. Extreme cases include one that was found {{convert|720|km|mi|abbr=on}} south of its nest near [[Karlstad]], Sweden, another set of four colour-marked first-year juveniles were also recorded to turn up in southern Sweden but one was found down to the [[Wadden Sea]] in the Netherlands and it is likely that trickling down numbers of Norwegian post-dispersal juveniles have gone onto form much of the known Dutch white-tailed eagle population.<ref name=Rijn/><ref name="Hagen,Y. 1976">Hagen,Y. (1976). ''Havørn og kongeørn i Norge''. Viltrapport, 1: 93 pg.</ref> 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 {{convert|520|km|mi|abbr=on}} west in northern Norway and another was found as far south as Bulgaria.<ref>Helander, B. (1985). ''Colour-ringing of white-tailed sea eagles in northern Europe''. Conservation studies on raptors.–ICBP Technical Publication, (5), 401–407.</ref><ref name="Stjernberg"/> In more southerly areas, winter movements are drawn-out and irregular, with most mature pairs probably never leaving their nesting haunts year-around.<ref name=Brown/> Those that breed on inland waterways may migrate to sea coast.<ref name= Brown/> German juveniles usually do not travel far, with most recorded to travel less than {{convert|50|km|mi|abbr=on}} 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, {{convert|1030|km|mi|abbr=on}} away to the southeast, or to [[Gironde]], [[France]], {{convert|1520|km|mi|abbr=on}} to the southwest.<ref name=vonBlotzheim>von Blotzheim, U. N. G., Bauer, K., & Bezzel, E. (1993). ''Handbuch der Vögel Mitteleuropas''. [[Akademische Verlagsgesellschaft]].</ref> In several parts of Russia, quite unlike many European populations, the white-tailed eagle seems to be largely migratory.<ref name=Ferguson-Lees/> 

In the far east, the species appear to take different migratory routes in autumn and spring, traveling from north-central [[Kamchatka]] thru the [[Kurile islands]] to Hokkaido in autumn, while in spring these eagles travel north through [[Sakhalin]] and the [[Okhotsk Coast]].<ref name=UetaSato>{{cite journal|last1=Ueta |first1=Mutsuyski |last2=Sato |first2=Fumio |last3=Lobkov |first3=Evgeni. G. |last4=Mita |first4=Nagashisa |orig-year=1998 |year=2008 |title=Migration route of White-tailed Sea Eagles Haliaeetus albicilla in northeastern Asia |journal=Ibis |volume=140 |issue=4 |pages=684–686 |doi=10.1111/j.1474-919X.1998.tb04715.x |s2cid=86622502}}</ref> In the [[White Sea]] area, southward moments begin in September with most white-tailed eagles being gone by November but in mild winters some adults may remain behind. Some white-tailed eagles from the White Sea were found well over {{convert|2000|km|mi|abbr=on}} away to the west, in countries such as Hungary and Italy. Return spring migration to the White Sea is by February–March.<ref name=Flerov/> During winter, whether long-distance migrants or short-distance dispersers, white-tailed eagles tend to become gregarious, especially younger immature birds. Many such groups can contain up to 10 and, in areas near large breeding populations such as the Scandinavian countries, up to at least 30–50 individuals.<ref name="Love-1983"/><ref name=Willgohs/><ref name=DOF17Aug2021/><ref name="JV-2023"/> Wintering congregations at the Baltic coast and on the [[Elbe|River Elbe]] from 37 winters show that arrivals begin in November, with numbers peaking in January and then declining during March and early April.<ref name=vonBlotzheim/> 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 {{convert|330|km|mi|abbr=on}} north of their natal site and {{convert|510|km|mi|abbr=on}} northeast of their natal site.<ref name=vonBlotzheim/>

===Territoriality===
Territory size in white-tailed eagles may vary from {{convert|52|to|415|km2|sqmi|abbr=on}}, usually less than {{convert|130|km2|sqmi|abbr=on}}, per one estimate.<ref name=Brown/> However, home ranges in northeastern Germany were much smaller than this, at {{convert|2.25|to|19.16|km2|sqmi|abbr=on}}.<ref>Krone, O., Nadjafzadeh, M., & Berger, A. (2013). ''White-tailed Sea Eagles (''Haliaeetus albicilla'') defend small home ranges in north-east Germany throughout the year''. Journal of Ornithology, 154(3), 827–835.</ref> While territorial behaviour is known in well more than half of all modern birds, essentially all predatory birds of different lineages are particularly strongly territorial because the live prey necessary to feed a family, including the female of the pair (which must remain near the young for them to survive) and the young themselves, tends to be sparser. Furthermore, appropriate habitat is needed in which to execute this hunting and also, of course, to build a nest with some security.<ref>Brown, J. L. (1969). ''Territorial behaviour and population regulation in birds: a review and re-evaluation''. The Wilson Bulletin, pp. 293–329.</ref> 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.<ref name="Love-1983"/><ref name=Brown/>

== Dietary biology ==
[[File:Haliaeetus albicilla, Mull 2.jpg|thumb|About to grasp a fish near the [[Isle of Mull]], Scotland]]

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.<ref name="Love-1983"/><ref name=Ferguson-Lees/> 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.<ref name="Love-1983"/><ref name=Valero>Valero, S.O.P. (2008). ''White-tailed Eagle hunting behaviour and food choice in Kvismaren''. Sveriges Ornitologiska Förening.</ref> 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 [[corvid]]s, [[Old World vulture|vultures]] or other raptors.<ref name="Love-1983"/> 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]], seldom hunting fish when they exceed a water depth of {{convert|1.5|to|2|m|ft|abbr=on}}.<ref name=Valero/><ref name=Nadjafzadeh2>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.</ref> In addition to trees, they may also use [[Cliff|crags]], [[hillock]]s or high [[Tussock (grass)|grassy tussocks]] as hunting perches so long as the perch provides a good overall view of the environment.<ref name="Love-1983"/><ref name=Willgohs/> 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.<ref name="Love-1983"/><ref name=Ferguson-Lees/> Occasionally, though, white-tailed eagles have been recorded [[Diving bird|plunging]] right into water, usually while hunting on the wing at a height of at least {{convert|200|m|ft|abbr=on}}. In Norway, plunge-diving is considered rare.<ref name=Willgohs/><ref name=vonBlotzheim/> At times they will also fish by wading into shallows, often from shores or gravel islands.<ref name="Love-1983"/> 

The species will at times variously follow [[Fishing vessel|fishing boats]], readily exploits commercial [[Fishery|fisheries]], [[Fish stocking|stocked lakes]], [[Koi pond|carp ponds]] and the like, and scavenges dead fish or [[Offal|fish-offal]] in a wide range of situations.<ref name=Ferguson-Lees/> When it comes to non-fish prey, it has been said that white-tailed eagles often hunt by flying low over [[Coast|sea coast]] or [[Marsh|lakeshore]] and attempt to surprise victims.<ref name=Brown/> However, the hunting success rates on healthy birds can be low as revealed in studying wintering eagles in Sweden attempting to hunt [[mallard]]s (''Anas platyrhynchos'').<ref name=Rudebeck>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.</ref> White-tailed eagles also regularly [[Kleptoparasitism|pirate]] food from [[otter]]s and other birds including [[cormorant]]s, [[gull]]s, [[osprey]]s, corvids and various other [[Bird of prey|raptors]].<ref name="Love-1983"/><ref name=vonBlotzheim/> [[Carrion]] is often the primary food source during lean winter months, with fish and [[ungulate]]s preferred but everything from [[cetacean]]s to [[livestock]] to even [[human]]s being eaten after death.<ref name=Ferguson-Lees/><ref name=rspb>{{cite web |title=White-tailed eagle: Feeding |url=http://www.rspb.org.uk/wildlife/birdguide/name/w/whitetailedeagle/feeding.aspx |publisher=[[RSPB]] |access-date=3 February 2012}}</ref> From studies of captive white-tailed eagles, daily food requirements were estimated at {{convert|500|to|600|g|lb|abbr=on}}, which is equivalent to about 10% of the birds' body weight, with crop contents commonly of {{convert|190|-|560|g|lb|abbr=on}}.<ref name=Brown/><ref name=Uttendorfer>Uttendorfer, O. (1939). ''Die Ernahrung der deutschen Raubvogel und Eulen''. Neudamm. Verlag Neumann, 204–209.</ref> Some semi-captive juveniles on the isle of [[Rùm]], Scotland could eat up to {{convert|1.4|kg|lb|abbr=on}} in one sitting.<ref name="Love-1983"/><ref name="Love-1988"/> 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 {{convert|625|g|lb|abbr=on}} per bird each day. Furthermore, one male consumed an estimated {{convert|2|kg|lb|abbr=on}} in a single meal upon capturing a large fish. The crop can bulge to the size of a small [[grapefruit]] after they've consumed a large meal.<ref name="Love-1983"/><ref name=Willgohs/>

[[File:Haliaeetus albicilla 1 (Bohuš Číčel).jpg|thumb|left|In winter, white-tailed eagles often live largely on carrion.]]
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.<ref name="Love-1983"/><ref name=Ferguson-Lees/><ref name="Mlíkovský-2009">Mlíkovský, J. (2009). ''The food of the white-tailed sea eagle (''Haliaeetus albicilla'') at Lake Baikal, East Siberia''. Slovak Raptor Journal, 3: 35–39.</ref> 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.<ref name="Love-1983"/><ref name=Vrezec>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.</ref> 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 favour fish. Going on pellet/remains alone here in Greenland from 557 items in the 1979 study, 68% of the diet would have 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.<ref name=Wille>Wille, F., & Kampp, K. (1983). ''Food of the white‐tailed eagle ''Haliaeetus albicilla'' in Greenland''. Ecography, 6(1), 81–88.</ref><ref name=Kampp>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).</ref> However, this kind of direct continuous observation of food deliveries to nests is not always possible.<ref name="Love-1983"/> 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.<ref name=Valero/><ref>Mersmann, T. J., Buehler, D. A., Fraser, J. D., & Seegar, J. K. (1992). ''Assessing bias in studies of bald eagle food habits''. The Journal of wildlife management, pp. 73–78.</ref> 

During winter, mammal prey can become more important in foods locally, as indicated in Scotland and shown in Norway and eastern Germany.<ref name="Love-1983"/> As much as 41% of the diet can be made up of mammals, as was the case on the [[Kola Peninsula]].<ref name=Flerov/> 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.<ref name=Willgohs/><ref name=Dornbusch>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.</ref> Among both fish and bird prey, it is thought that a majority that are caught weigh between {{convert|0.5|and|3|kg|lb|abbr=on}}.<ref name="Love-1983"/> At times it has been said that "most" prey of white-tailed eagles will weigh only {{convert|0.5|to|1|kg|lb|abbr=on}}.<ref name=Sulkava>Sulkava, S., Tornberg, R., & Koivusaari, J. (1997). ''Diet of the white-tailed eagle ''Haliaeetus albicilla'' in Finland''. Ornis Fennica, 74(2), 65–78.</ref> However, the mean prey sizes caught can show greater variability. Three studies showed that mean prey size varied from {{convert|578|g|lb|abbr=on}} in the [[Wigry National Park]], Poland,{{convert|1062.1|g|lb|abbr=on}} in the [[Rybinsk Reservoir]], Russia and {{convert|1.72|kg|lb|abbr=on}} in the [[Volga-Kama Nature Reserve]], Russia.<ref name=Zawadzka>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.</ref><ref>Babushkin, M. V., Kuznetsov, A. V., & Demina, O. A. (2017). ''White-Tailed Eagle on the Rybinsk reservoir: abundance, ecology, migration and wintering sites''. In The collection of Abstracts and Short Notes of the SEA EAGLE 2017 conference (pp. 5–7).</ref><ref>Ayupov, A.S. (2017). ''The use of camcorder in nesting biology research of ''Haliaeetus albicilla'' (L)''. In The collection of Abstracts and Short Notes of the SEA EAGLE 2017 conference (p. 13).</ref> Thus, the mean prey size falls just slightly short of the mean prey mass of the golden eagle, which globally averages about {{convert|1.35|to|1.63|kg|lb|abbr=on}}.<ref name=Watson/>

===Fish===
[[File:Sea Eagle (14992790955).jpg|thumb|White-tailed eagle with caught fish]]
Overall, nearly 70 species of fish are known to be taken from throughout the white-tailed eagle's range.<ref name="Love-1983"/><ref name=Vrezec/> White-tailed eagles can hunt fish in fresh or saltwater as well as those that prefer brackish water areas. However, they are restricted to taking fish in extremely shallow water, often by preference in water less than {{convert|1|m|ft|abbr=on}} deep.<ref name="Love-1983"/> Ideal fishing areas can be found in areas such as the Baltic Sea, where low coasts and archipelagos often have relatively shallow water.<ref name=Bergman>{{cite journal |last1=Bergman |first1=Göran |year=1961 |title=The food of birds of prey and owls in Fenno-Scandia |journal=British Birds |volume=54 |issue=8 |pages=307–320 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V54/V54_N08/V54_N08_P307_320_A051.pdf}}</ref> 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 [[Diphyllobothrium|fish tapeworm]], as is often the case with some fish families such as [[carp]].<ref name="Love-1983"/><ref>Bolam, G. (1913). ''Wild life in Wales''. F. Palmer.</ref> 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.<ref name="Love-1983"/> [[Demersal fish|Benthic fish]] which tend to cling to rocks or sandy soil in shallows may be more vulnerable since they tend to look downward rather than upward and are less competent at escaping predators coming from above the water's surface. Therefore, lurking benthic fish such as [[lumpsucker]]s are more vulnerable than many.<ref name=Willgohs/> 

Besides vulnerability, habitat, and prey behavior, fish body size may be a driver in the piscivore's dietary preferences. White-tailed eagles usually can take various fish from {{convert|0.1|to|8|kg|lb|abbr=on}}, but fish ranging {{convert|0.5|to|3|kg|lb|abbr=on}} typically preferred.<ref name="Love-1983"/><ref name=Tadeusz>Tadeusz Mizera: Bielik. Świebodzin: Wydawnictwo Lubuskiego Klubu Przyrodników, 1999, s. 195, seria: Monografie Przyrodnicze, nr 4.</ref> Similarly, studies have indicated that fish less than {{convert|20|cm|in|abbr=on}} are taken infrequently, since they have a lower yield, fish of up to {{convert|30|cm|in|abbr=on}} are taken secondarily and fish between {{convert|30|and|60|cm|ft|abbr=on}} are preferred since they have the highest nutritional benefit. Fish taken can exceed {{convert|0.9|to|1|m|ft|abbr=on}} but since they can start to considerably exceed the weight of the eagle itself, they may prove too heavy to carry.<ref name="Love-1983"/><ref name=Valero/><ref name=Nadjafzadeh2/> One large [[Atlantic halibut]] (''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.<ref>Buckley, T. E., & Harvie-Brown, J. A. (1891). ''A vertebrate fauna of the Orkney Islands (Vol. 4)''. D. Douglas.</ref> 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 fly to a feeding perch or nest as soon as possible most of the time.<ref name="Love-1983"/><ref name=Nadjafzadeh2/> 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.<ref name=Willgohs/><ref>Wille, F. (1979). ''Choice of Food of the Greenland White-tailed Eagle- method and preliminary results''. Dansk ornithogisk Forenings Tidsskrit, 73: 165–170.</ref>

The most frequently recorded prey species in 18 food studies from across the range is the [[northern pike]] (''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 (Sweden)|Lapland]] in Sweden, at three breeding locations in Finland, in two studies from Germany, and in [[Belarus]]. The maximum representation of pike known was in Lapland, where they comprised 38.2% of 809 food items.<ref name=Vrezec/><ref name=Sulkava/><ref name=Fischer1>Fischer W. (1982). ''Die Seeadler'' . Die Neue Brehm-Bücherei , A. Ziemsen Verlag , WittenbergLutherstadt.</ref><ref name=Ekblad>Ekblad, C. (2004). ''Havsörnens häckningstida näringsval i olika skärgårdszoner på Åland''. Doktorsavhandling. Institutionen för Ekologi och Systematik. Avdelningen för populationsbiologi. Februari.</ref> While an average mature weight for a pike is around {{convert|1.4|kg|lb|abbr=on}}, white-tailed eagles often attack larger-sized pike, with an estimated average weight range of {{convert|2|to|5|kg|lb|abbr=on}}.<ref name="Love-1983"/><ref name=Flerov/><ref name="Adrianova">Babushkin, M. V. (2005, November). Species diversity, population and ecology of raptors on the northeastern shore of the Rybinsk reservoir. In Status of raptor population in Eastern Fennoscandia: proceedings of the workshop, Kostomuksha, Karelia, Russia (pp. 10-22).</ref><ref>Sternberg, D. (1992). ''Northern Pike and Muskie: Tackle and Techniques for Catching Trophy Pike and Muskie''s. Creative Publishing International.</ref> The largest pike taken by white-tailed eagles were even estimated to weigh around {{convert|12|to|15|kg|lb|abbr=on}}.<ref>GILYAZOV, A. (2005, November). Population of diurnal raptors (Falconiformes) in the Lapland Nature Reserve and adjacent areas: Dynamics in 1930–2005. In Status of Raptor Populations in Eastern Fennoscandia. Proceedings of the Workshop, Kostomuksha, Karelia, Russia (pp. 35-43).</ref> 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]] region of Russia, and in the [[Kostomuksha Nature Reserve]], Russia.<ref name="Adrianova"/><ref name=Yurko>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.</ref><ref name=Samago>Samago, L. (1995). ''White-tailed eagle - ''Haliaeetus albicilla'' L.'' Propagation of the Urals and adjacent territories to poly-terrestrial sources: 107–122.</ref> Breams taken by reeding eagles at [[Augustów Forest]], [[Poland]] ranged from {{convert|0.2|to|2|kg|lb|abbr=on}} in weight.<ref name =Zawadzka.>Zawadzka D., Zawadzki J., Sudnik W. (2006): Rozwój populacji, wymagania środowiskowe I ekologia bielika Haliaeetus albicilla w Puszczy Augustowskiej. Notatki Ornitologiczne 47: 217–229.</ref>

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.<ref name=Valero/><ref name=Nadjafzadeh2/> Particularly diverse in the white-tailed eagle's prey spectrum are the family [[Cyprinidae]], of which more than 20 species are known to be predated including the common bream.<ref name="Love-1983"/><ref name=Vrezec/> Others taken with some preference may include [[salmonid]]s and [[Gadidae|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.<ref name="Love-1983"/> In Greenland, the leading prey species is the salmonid, the [[Arctic char]] (''Salvelinus alpinus''), which comprised 27.2% of 660 prey items. The secondary prey in Greenland was recorded as two species of [[cod]]. While the average weight of cod taken here was estimated at only {{convert|420|to|640|g|lb|abbr=on}} and the average char at {{convert|660|to|740|g|lb|abbr=on}}, The eagles occasionally brought larger individuals up to {{convert|2.2|kg|lb|abbr=on}} for cods and up to {{convert|3.2|kg|lb|abbr=on}} for chars respectively.<ref name=Wille/><ref>Harris, L. N., Tallman, R. F., & Department of Fisheries and Oceans, Ottawa, ON(Canada); Canadian Science Advisory Secretariat, Ottawa, ON(Canada). (2010). ''Information to support the assessment of Arctic Char, Salvelinus alpinus, from the Isuituq River system, Nunavut''. Fisheries and Oceans Canada, Science.</ref> In Norway, of 524 fish prey items, the [[Cyclopterus lumpus|common lumpsucker]] (''Cyclopterus lumpus''), which averages up to {{convert|1.43|kg|lb|abbr=on}} but is usually smaller, made up 24% of fish taken and the {{convert|2.13|kg|lb|abbr=on}} [[Atlantic wolffish]] (''Anarhichas lupus'') made up 17% of fish taken.<ref name=Willgohs/><ref>Collette, B., Fernandes, P. & Heessen, H. 2015. ''Anarhichas lupus''. The IUCN Red List of Threatened Species 2015: e.T18155993A44739312.</ref><ref>Simpson, M.R., Gauthier, J., Benoît, H.P., MacDonald, D., Hedges, K., Collins, R., Mello, L. & Miri, C. (2016). ''A pre-COSEWIC assessment of the Common Lumpfish (Cyclopterus lumpus, Linnaeus 1758) in Canadian Atlantic and Arctic waters''. Canadian Science Adversary.</ref> However, fish were secondary to birds overall in Norway.<ref name=Willgohs/> Per two studies from Sweden, fish were usually the main food unlike in Norway and Finland, and could comprise 51–60% of the diet.<ref name=Vrezec/><ref name=Sulkava/><ref name=Ekblad/> Fish were also somewhat dominant in the foods from two studies in Belarus, making up 48.1–53.7% of the diet.<ref name=Yurko/><ref name=Ivanovsky>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.</ref> Fish similarly were important to nesting eagles in Hokkaido, Japan where 54% of 533 prey items were fish, led by the {{convert|800|g|lb|abbr=on}} [[Alaska pollock]] (''Gadus chalcogrammus'') at 18.4%.<ref name=Mori>Mori, S. (1980). ''Breeding biology of the White-tailed Eagle ''Haliaeetus albicilla'' in Hokkaido, Japan''. Japanese Journal of Ornithology, 29(2–3), 47–68.</ref><ref>Bailey, K. M., Powers, D. M., Quattro, J. M., Villa, G., Nishimura, A., Traynor, J. J., & Walters, G. (1999). ''Population ecology and structural dynamics of walleye pollock (Theragra chalcogramma)''. Dynamics of the Bering Sea, pp. 581–614.</ref> In different studies of the [[Danube Delta]] of Romania, from 44.6% to 79% of the diet was comprised by fish, led by the [[common carp]] (''Cyprinus carpio'') and [[Prussian carp]] (''Carassius gibelio'').<ref name="Love-1983"/><ref name=Sandor>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.</ref><ref>Tuvia, J., & Välia, Ü. (2007). ''The impact of the White-tailed Eagle ''Haliaeetus albicilla'' and the Osprey ''Pandion haliaetus'' on Estonian Common Carp Cyprinus carpio production: How large is the economic loss?'' Estonian Journal of Ecology, 56(3).</ref> Similarly, in [[Podlaskie Voivodeship]], [[Poland]] 55% of all the identified fish species brought to the nest were common carps, up to {{convert|2.1|kg|lb|abbr=on}} in weight with the mean mass of {{convert|493|g|lb|abbr=on}}.<ref name =Mirski>Mirski, Paweł, and Ervin Komar. "The White-Tailed Eagle, the Apex Predator, Adjusts Diet towards Larger Prey in Suboptimal Territories." Diversity 15.6 (2023): 747.</ref> However, there are reports that white-tailed eagles managed to catch extreme sizes of carps, up to {{convert|15|kg|lb|abbr=on}}in weight.<ref name = Kiss>Kiss J.B., Sándor A., Alexe V., Doroșencu A., Marinov M. 2014. Date privind situaţia actuală a codalbului Haliaeetus albicilla (L.) în Delta Dunării - România şi contribuţii la cunoaşterea regimului său trofic în perioada reproducerii. Revista Pădurilor. București. 129 (1-2) pp. 77-86</ref>

===Birds===
[[File:An adult white-tailed eagle (Haliaeetus albicilla) defending its prey.jpg|thumb|An adult white-tailed eagle with an apparent bird kill, of unidentified species. It is warding off [[Carrion crow|crow]]s wishing to scavenge it.]]
White-tailed eagles are known to prey on about 170 species of bird, the most diverse group in their prey spectrum.<ref name="Love-1983"/><ref name=Willgohs/><ref name=Vrezec/> 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.<ref name="Love-1983"/><ref name=Nadjafzadeh2/> For example, [[grey heron]]s (''Ardea cinerea'') have been caught after an eagle used a low flight over turbulent water to ambush them.<ref name=Willgohs/> However, even with a stealthy attack, the [[waterfowl]] favoured in the avian diet tend to be highly wary and will more often than not escape.<ref name=Rudebeck/> 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.<ref name="Love-1983"/> [[Diving duck]]s 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 eider]]s (''Somateria mollissima''), with their pale plumage, may be easier to see under water and so may be taken somewhat more via this hunting method.<ref name="Love-1983"/><ref name=Willgohs/> Beyond waterfowl, both [[loon]]s and [[grebe]]s have been seen to be successfully hunted in this way.<ref name="Love-1983"/> 

Eagles were recorded doing up to 12 attacks on [[eider]]s 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'').<ref name=vonBlotzheim/><ref name=Flerov/> While bald eagles may attack diving ducks in the same way, they appear to do so somewhat less regularly and successfully.<ref>Todd, C. S., Young, L. S., Owen Jr, R. B., & Gramlich, F. J. (1982). ''Food habits of bald eagles in Maine''. The Journal of Wildlife Management, pp. 636–645.</ref><ref name=Buehler>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.</ref> White-tailed eagles usually have less success hunting [[dabbling duck]]s because their normal predator response behaviour 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]] (''Anser fabalis'') was even recorded to have defended itself successfully against an eagle's attack even though this goose was injured.<ref name=Rudebeck/> White-tailed eagles often hunt dabbling ducks and geese most successfully when they are [[moult]]ed into their [[Plumage|eclipse plumage]] which renders them temporarily flightless.<ref name="Love-1983"/> [[Swan]]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.<ref name=Fischer2>Fischer, W. (1970). ''Die Seeadler''. A. Ziemsen Verlag.</ref> They've also been seen to attack numerous waterfowl when the birds are injured by buckshot from duck hunters.<ref name=Fischer2/> Due to their status as enemy of other large birds, they are frequently [[Mobbing (animal behaviour)|mobbed]] 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]] (''Accipiter gentilis'').<ref name="Love-1983"/><ref name=Meinertzhagen>Meinertzhagen, R. (1959). ''Pirates and Predators: The piratical and predatory habits of birds''. Oliver and Boyd.</ref> 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]], large corvids or other accipitrids.<ref name=Uttendorfer/> In Germany and Scotland, up to 86% of gulls taken were nestlings and juveniles.<ref name=Fischer1/><ref>Wolley, J. (1907). ''Ootheca Wolleyana: an illustrated catalogue of the collection of birds' eggs''. Repressed Publishing LLC.</ref> 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 [[kittiwake]]s, [[eider]]s, cormorants and gulls.<ref name=vonBlotzheim/><ref name=Fischer2/>

The most widely recorded avian prey species and, second most widely recorded prey species behind the pike, is the {{convert|1.14|kg|lb|abbr=on}} mallard, due to its circumpolar range and commonality in many wetlands areas.<ref name="Love-1983"/><ref name="CRC"/><ref name=Vrezec/> 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.<ref name="Love-1983"/><ref name=Rudebeck/> 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]] in Germany, where mallards were the third best represented prey species at 10.1% of 247 items and from [[Augustów Primeval Forest]] in Poland, where mallards were the second most numerous prey and made up 9.84% of 803 items.<ref name=Vrezec/><ref name=Fischer1/> Taken more preferentially where they occur are common eiders. When hunting eiders, perhaps the largest of diving ducks at a mean weight of {{convert|2.06|kg|lb|abbr=on}}, white-tailed eagles frequently force the eider to dive repeatedly until it is exhausted and can be captured.<ref name=Willgohs/><ref name="CRC"/><ref name=Flerov/> 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.<ref name=vonBlotzheim/><ref>Kilpi, M., & Öst, M. (2002). ''The effect of White-tailed Sea Eagle predation on breeding Eider females off Tvärminne, Western Gulf of Finland''. Suomen Riista, 48: 27–33.</ref> Otherwise the pale plumage of adult male common eiders while they're diving is reported to make them more vulnerable to eagle attacks.<ref name="Love-1983"/><ref name=Willgohs/> Eiders were the leading prey species in Norway making 18.8% of 1612 prey items, as well as in [[Åland]], Finland where the eider comprised 18.63% of 5161 prey items (thus nearly a thousand eiders were taken here).<ref name=Willgohs/><ref name=Vrezec/><ref name=Ekblad/> Eiders also appeared to be the main prey species in Iceland.<ref name="Ingólfsson">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.</ref> 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.<ref>Ravn Merke, F., & Mosbech, A. (2008). ''Diurnal and nocturnal feeding strategies in common eiders''. Waterbirds, 31(4), 580–586.</ref><ref name=Hipfner>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.</ref> In inland regions, an avian prey species preferred by white-tailed eagles is the {{convert|836|g|lb|abbr=on}} [[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.<ref name="Love-1983"/><ref name="CRC"/><ref name=Vrezec/> 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.<ref name="Love-1983"/> 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.<ref name=Rudebeck/><ref name=Valero/><ref name=Nadjafzadeh2/> 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.<ref name=Vrezec/><ref name=Zawadzka/> 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.<ref name=Fischer2/><ref name=Sandor/>

[[File:Somateria mollissima - Holzbrücke 2011-03-24 15-21-26.JPG|thumb|Swimming male [[common eider]]s are a frequent quarry of white-tailed eagles.]]

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 [[Rail (bird)|rails]], [[Procellariiformes|tubenose]]s as well as [[heron]]s, [[stork]]s and other assorted large waders. White-tailed eagles also are known to hunt some 42 species of [[shorebird]], most significantly gulls and [[alcid]]s.<ref name="Love-1983"/><ref name=Vrezec/><ref name=Ekblad/> Even shorebirds as small as {{convert|21.1|g|oz|abbr=on}} [[little stint]] (''Calidris minuta''), {{convert|62.6|g|oz|abbr=on}} [[wood sandpiper]] (''Tringa glareola'') and {{convert|64|g|oz|abbr=on}} [[common ringed plover]] (''Charadrius hiaticula'') are known to be preyed upon, albeit quite rarely.<ref name="CRC"/><ref name=Sulkava/><ref>Ryabtsev, V.V. (1997). ''The White-tailed Sea Eagle ''Haliaeetus albicilla'' in Baikal Lake''. Russian Ornithological Journal, 20: 3–12.</ref> More than a dozen gulls are known in the prey spectrum from the [[Little gull|smallest]] to all four largest extant species.<ref name="Wille" /><ref name=Sulkava/><ref name="Mlíkovský-2009"/><ref>Vasilievich, S.B. (2014). ''Nesting of the White-tailed Sea Eagle ''Haliaeetus albicilla'' in the Black Irtysh''. Russian Ornithological Journal, 1007: 1720–1725.</ref> In the [[United Kingdom]], [[northern fulmar]] (''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.<ref name=rspb/> 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".<ref name="Love-1983"/><ref name=Broad>{{cite journal |last1=Broad |first1=Roger A. |year=1974 |title=Contamination of birds with Fulmar oil |journal=British Birds |volume=67 |issue= |pages=297–301 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V67/V67_N07/V67_N07_P297_301_A049.pdf}}</ref> Alcids such as [[murre]]s 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.<ref name=Willgohs/><ref name=Hipfner/> 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.<ref name="Love-1983"/><ref name=Fischer2/> 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]], where they comprised 51.8% of 199 prey items.<ref name="Mlíkovský-2009"/><ref name="Mlíkovský-1992">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.</ref> In [[Fennoscandia]], they are attracted to coastal waters during winter to attack large numbers of diving ducks including eiders, [[common goldeneye]] (''Bucephala clangula''), [[Common merganser|goosander]] (''Mergus merganser'') and [[red-breasted merganser]] (''Mergus serrator''), [[tufted duck]]s (''Aythya fuligula'') and [[scoter]]s. Year around in [[Åland]], 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.<ref name=Sulkava/><ref name=Bergman/><ref name=Ekblad/> 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%<ref name=Fischer1/><ref name=Vrezec/> 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.<ref name="Love-1983"/><ref name=Flerov/> 
[[File:Haliaetus albicilla EM1B6120 (35944276502).jpg|thumb|left|Juvenile white-tailed eagle pursuing two [[northern lapwing]]s]]
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 moulting dabbling water birds), white-tailed eagles routinely attack larger water birds as well. In many areas, large numbers of [[greylag 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.<ref name="CRC"/><ref name=Rijn/><ref name=Vrezec/><ref name=Probst>Probst, R. (2009). ''Der Seeadler (''Haliaeetus albicilla'') in Österreich'': Das WWF Österreich Seeadlerprojekt. Denisia, 27, 29–50.</ref> They will take many goslings during summer, as greylag goslings alone can comprise up 23% of the seasonal bird prey. Fully-grown greylag geese up to {{convert|4|kg|lb|abbr=on}}, especially infirm individuals are also taken in other seasons.<ref name="Love-1983"/><ref name=Fischer2/><ref name = roy>Roy Dennis. (2019). "The feasibility of reintroducing White-tailed Eagles Haliaeetus albicilla to the Isle of Wight and the Solent"</ref><ref>{{cite web|title=On the Menu|url=https://www.isle-of-mull.net/wildlife/eagles/white-tailed-eagles/on-the-menu/|publisher=MullWeb.site 2023|access-date=February 4, 2024}}</ref> White-tailed eagles are also known to attack and prey on other geese, ranging in size from the {{convert|1.23|kg|lb|abbr=on}} [[red-breasted goose]] (''Branta ruficollis'') to the non-native {{convert|3.69|kg|lb|abbr=on}} [[Canada goose]] (''Branta canadensis'').<ref name="CRC"/><ref name = black>Black, Jeffrey M., Jouke Prop, and Kjell Larsson. The barnacle goose. Bloomsbury Publishing, 2014.</ref><ref>Berezovikov,  N.N. (2006). ''White-Tailed Eagle Haliaeetus Albicilla and the Local Concentration of Water Birds On Lakes of North Kazakhstan''. Russian Ornithological Journal, 335: 1028–1030.</ref><ref>Kruckenberg, Helmut, Jochen Bellebaum, and Volkhard Wille. "Escape distances of staging Arctic geese along the flyway." Vogelwelt 129 (2008): 169-173.</ref><ref>Ouweneel, O., & van Straalen, D. (2016). ''Paalzittende Zeearenden ''Haliaeetus albicilla'' op de Hellegatsplaten''. De takkeling, 24(3), 188–193.</ref> Goslings and juveniles are usually targeted, but adult geese are also taken, especially while incubating or weakened by various reasons.<ref name = roy/><ref name = black/> Another large water bird taken as adults are {{convert|4.98|kg|lb|abbr=on}} [[common loon]]s (''Gavia immer'').<ref name="Love-1983"/><ref name="CRC"/> Large waders are taken when possible, including [[grey heron]]s and [[great bittern]]s (''Botaurus stellaris''), both weighing between {{convert|1|and|2|kg|lb|frac=4|abbr=on}}.<ref name=Vrezec/><ref name=Willgohs/> Larger {{convert|2.93|kg|lb|abbr=on}} [[Black stork|black]] and the {{convert|3.44|kg|lb|abbr=on}} [[white stork]] (''Ciconia ciconia'') of all ages can be preyed upon. Black and white storks are the 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 storks were also taken in Augustów Primeval Forest where remains of nearly 50 individuals were found around eagle nests.<ref name="Love-1983"/><ref name=Vrezec/><ref name=Sulkava/><ref name=Yurko/> White-tailed eagles even attack and prey on both the young and adults of {{convert|5.1|kg|lb|abbr=on}} [[common crane]]s (''Grus grus'').<ref name =Mirski/> The largest waterbirds species preyed upon are swans, including [[Mute swan|mute]] (''Cygnus olor''), [[Whooper swan|whooper]] (''Cygnus cygnus'') and [[Bewick's swan]]s (''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 preyed upon even healthy adult swans up to {{convert|10|kg|lb|abbr=on}}.<ref name="Love-1983"/><ref name=Vrezec/><ref name=Zawadzka/><ref>Brazil, M. (2010). ''The whooper swan''. Bloomsbury Publishing.</ref><ref name = Kiss/>

They are reported to have attacked and eaten the largest seabirds they encounter, such as [[great cormorant]]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 {{convert|2.57|kg|lb|abbr=on}}.<ref name="CRC"/><ref name=hs.fi>{{cite web |title=Turun Sanomat: Merikotkat oppineet syömään aikuisiakin merimetsoja |url=http://www.hs.fi/kotimaa/artikkeli/Turun+Sanomat+Merikotkat+oppineet+sy%C3%B6m%C3%A4%C3%A4n+aikuisiakin+merimetsoja/1135256870866/?cmp=tm_etu_uusimmat_uutiset |access-date=3 February 2012 |language=fi}}</ref> In the [[Estonia]]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.<ref name=Hiiumaa>{{cite web |title=Kormoraniküttidel läheb hästi |trans-title=Cormorant Hunters are doing well <!-- Google translated --> |website=eestielu.delfi.ee |url=http://eestielu.delfi.ee/hiiumaa/elu/loodus-reguleerib-kormoranikuttidel-laheb-hasti?id=64246361 |date=13 April 2012 |language=et}}</ref> Similarly large numbers were taken of the {{convert|2.82|kg|lb|abbr=on}} [[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]] colonies are accessed, great numbers of {{convert|3|kg|lb|abbr=on}} [[northern gannet]]s (''Morus bassanus'').<ref name="CRC"/><ref name=Mori/><ref name=Whitfield>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.</ref> Vagrant white-tailed eagles in [[Hawaii]] were recorded to prey on several [[Laysan albatross]] (''Phoebastria immutabilis'') and were suspected to prey on [[black-footed albatross]] (''Phoebastria nigripes''), both weighing about {{convert|3.17|kg|lb|abbr=on}}.<ref name="CRC"/><ref>Zaun, B. J. (2009). ''First modern record of the White-tailed Eagle in Hawaii''. Western Birds, 40: 35–38.</ref>

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.<ref name="Love-1983"/><ref name=Vrezec/> For the most part, land birds are taken so infrequently as to not warrant much mention. However, variable numbers of [[gamebird]]s are taken opportunistically, and in Belarus and Russia, especially around the [[White Sea]] 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.<ref name=Flerov/><ref name=Ivanovsky/><ref name=Probst/> They will at times attack adult male [[western capercaillie]] (''Tetrao urogallus''), of note for their large size at {{convert|4.2|kg|lb|abbr=on}}.<ref name=Adrianova/> 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 {{convert|15|kg|lb|abbr=on}} (which, much like exceptionally large fish taken, must have been consumed in the killing spot or subsequently dismantled as too large to fly with).<ref name="Love-1983"/> Among the land birds taken, more than 20 [[passerine]]s are included in the prey spectrum but most are obviously too small and swift to be anything but incidental prey.<ref name="Love-1983"/> The smallest avian prey known for white-tailed eagles was a [[great tit]] (''Parus major''), a species which weighs {{convert|16.4|g|oz|abbr=on}} on average.<ref name="CRC"/><ref>Müller, H. (2011). ''Brutbiologische Beobachtungen an einem Seeadler ''Haliaeetus albicilla''-Brutplatz in Bayern''. Ornithol. Anz, 49: 193–200.</ref> 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 [[Flocking (behavior)|murmuration]] of [[Eurasian starling]]s (''Sturnus vulgaris'') and come away with a starling in hand.<ref name="Love-1983"/><ref name=Willgohs/> The only passerine family taken in numbers would be the larger corvids, of which eight species are known in the prey spectrum.<ref name=Sulkava/><ref name=Sandor/><ref name=Samago/> In Hokkaido, Japan, two species of corvid were well-represented in the diet, the {{convert|519.5|g|lb|abbr=on}} [[large-billed crow]] (''Corvus macrorhynchos'') and the {{convert|570|g|lb|abbr=on}} [[carrion crow]] (''Corvus corone''), which together comprised 14.8% of 533 prey items.<ref name="CRC"/><ref name=Mori/>

===Mammals and other prey===
[[File:British birds with their nests and eggs (1896) (14747475321).jpg|thumb|1896 rendering of a white-tailed eagle with [[European rabbit|rabbit]] 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.<ref name="Love-1983"/> In known dietary studies, the mammalian contribution can vary from 0.49% to 41% of prey by number.<ref name="Love-1983" /><ref name=Flerov/><ref name=Vrezec/> When mammals are most significant to the diet, it usually due to local white-tailed eagles preying on [[Leporidae|rabbits and hares]] with some regularity.<ref name=Whitfield/> While [[mountain hare]]s (''Lepus timidus'') only comprise 1.4% of total prey in [[Finland]], the proportion of mountain hares in the diet of White-tailed Eagles taken from [[Norway]] to [[Scotland]] is around 20.3%, which indicates that White-tailed Eagles are, when necessary, well capable of hunting on land and catching hares.<ref name=Sulkava/> Other studies from Scotland indicate [[mountain hare]]s along with the [[European rabbit]] (''Oryctolagus cuniculus'') were found to contribute as much as nearly 20% to 40% of the diet at times.<ref name=Whitfield/><ref name=Halley>{{cite journal |last1=Halley |first1=D. J. |year=1998 |title=Golden and White-tailed Eagles in Scotland and Norway. Coexistence, competition and environmental degradation |journal=British Birds |issn=0007-0335 |s2cid=56392681 |volume=91 |issue=5 |pages=171–179 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V91/V91_N05/V91_N05_P171_179_A044.pdf}}</ref><ref name=Watson2>{{cite journal|last1=Watson |first1=J. |last2=Leitch |first2=A. F. |last3=Broad |first3=R. A. |year=1992 |title=The diet of the Sea Eagle Haliaeetus albicilla and Golden Eagle Aquila chrysaetos in western Scotland |journal=Ibis |volume=134 |issue=1 |pages=27–31 |doi=10.1111/j.1474-919X.1992.tb07225.x |s2cid=83483229}}</ref><ref>Forrest, H. E. (1907). ''The vertebrate fauna of North Wales''. Witherby.</ref><ref>MacGillivray, W. (1836). ''Descriptions of the Rapacious Birds of Great Britain.[With plates.]''. Maclachlan & Stewart.</ref> A similar contribution of [[European hare]]s (''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).<ref name=Probst/> In studies from Germany, European hares were taken fairly often but were numerically secondary prey.<ref name=Vrezec/><ref name=Fischer1/> These rabbits and hares have average mature weights from {{convert|1.8|kg|lb|abbr=on}} in rabbits, {{convert|2.7|kg|lb|abbr=on}} for mountain hares, 
{{convert|3.8|kg|lb|abbr=on}} in European hares.<ref>Chapman, J. A., & Flux, J. E. (Eds.). (1990). ''Rabbits, hares and pikas: status survey and conservation action plan''. IUCN.</ref><ref>Angerbjörn, A. (1995). ''Lepus timidus''. Mammalian species, (495), 1–11.</ref> As large prey, they can make a hearty contribution to the prey biomass when available juveniles are attacked as much if not more so than adult rabbits and hares.<ref name=Watson2/><ref>Tomáš, B., & HORAL, D. The White-tailed Eagle (Haliaeetus albicilla) in the Czech Republic.</ref>

The most widely reported mammalian prey known usually as a supplemental prey species are [[rodent]]s, especially the non-native [[muskrat]] (''Ondatra zibethicus''), which averages about {{convert|1.1|kg|lb|abbr=on}}, 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.<ref name="Love-1983"/><ref name=Sulkava/><ref>Feldhamer, G. A., Thompson, B. C., & Chapman, J. A. (Eds.). (2003). ''Wild mammals of North America: biology, management, and conservation''. JHU Press.</ref> Also, a study on the [[Ili River|Ili delta]] in Kazakhstan has shown up to 30–43% of prey remains at eyries to consist of muskrat in spring and autumn but only 14% in summer (for unknown reasons).<ref name=vonBlotzheim/> In total, about 20 [[rodent]] 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.<ref name=Flerov/><ref name=Samago/> Even agile [[red squirrel]]s (''Sciurus vulgaris'') may be caught from trees in some cases.<ref>Berg, B. (1923). ''De sista örnarna''. Norstedt.</ref> The smallest rodents known in the prey spectrum are the {{convert|27.4|g|oz|abbr=on}} [[common vole]] (Microtus arvalis) and the {{convert|23.4|g|oz|abbr=on}} [[wood mouse]] (''Apodemus sylvaticus'') but mammalian prey down to the size of {{convert|8.1|g|oz|abbr=on}} [[common shrew]]s (''Sorex araneus''), indeed the smallest vertebrate known to have been preyed upon, has been recorded.<ref name="Love-1983"/><ref name=Samago/><ref>Korpimäki, E., & Norrdahl, K. (1989). ''Avian and mammalian predators of shrews in Europe: regional differences, between-year, and seasonal variation, and mortality due to predation''. In Annales Zoologici Fennici (pp. 389–400). Finnish Zoological Publishing Board, formed by the Finnish Academy of Sciences, Societas Scientiarum Fennica, Societas pro-Fauna et Flora Fennica and Societas Biologica Fennica Vanamo.</ref> The largest rodents taken by white-tailed eagles are [[nutria]] (''Myocastor coypus'') and kits of [[Eurasian beaver|Eurasian]] (''Castor fiber'') and introduced [[North American beaver]]s (''Castor canadensis'').<ref name=Yurko/><ref>Božić, B., Puškarić, V., Delić, D., Meštrović, L., Mandić, K., Mandić, A., ... & Castle, P. (2022). The first breeding of the White-tailed Eagle Haliaeetus albicilla in the Istria County. Larus-Godišnjak Zavoda za ornitologiju Hrvatske akademije znanosti i umjetnosti, 57(1), 89-90.</ref><ref>Rosell, F., Bozser, O., Collen, P., & Parker, H. (2005). ''Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems''. Mammal review, 35(3‐4), 248–276.</ref>
[[File:Merikotkas kanarbikus.jpg|thumb|left|White-tailed eagle adult on the island of [[Hiiumaa]] in [[Estonia]]]]
More than a dozen ungulate species have been found in the foods of white-tailed eagles, but a large proportion of this is likely from carrion found already dead.<ref name=Sulkava/> Large food sources such as [[horse]]s (''Equus ferus caballus''), [[moose]] (''Alces alces''), [[cattle]] (''Bos taurus'') and [[European bison]] (''Bison bonasus'') are certainly visited as carrion always.<ref name="Love-1983"/><ref name=Rijn/><ref name=Sulkava/><ref>Selva, N., Jedrzejewska, B., Jedrzejewski, W., & Wajrak, A. (2003). ''Scavenging on European bison carcasses in Bialowieza primeval forest (eastern Poland)''. Ecoscience, 10(3), 303–311.</ref> Wild ungulate species known to have their young attacked by white-tailed eagles in variable numbers may include deer such as [[reindeer]] (''Rangifer tarandus''), [[red deer]] (''Cervus elaphus'') and [[European roe deer]] (''Capreolus capreolus'') and [[wild boar]] (''Sus scrofa''). Boar made up 7.1% of the prey remains at Polesski Reserve, Belarus.<ref name="Love-1983"/><ref name=Willgohs/><ref name=Yurko/> At least two attacks on adult roe deer have been reported, which could potentially weigh around {{convert|25.4|kg|lb|abbr=on}} (their average mature weight), in addition to several cases of predation on young roe deer.<ref name=Willgohs/><ref>MacGillivray, W. (1836). ''Descriptions of the Rapacious Birds of Great Britain''. [With plates.]. Maclachlan & Stewart.</ref><ref>Alexander, T. L., & Buxton, D. (Eds.). (1986). ''Management and diseases of deer: a handbook for the veterinary surgeon''. Veterinary Deer Society.</ref><ref>Gorbet, G.B. & Harris, S. (1991). ''The Handbook of British Mammals, Third Edition''. Blackwell Science Publications. {{ISBN|0-632-01691-4}}.</ref> A yearling juvenile male eagle scaling {{convert|5|kg|lb|abbr=on}}, newly reintroduced into the wild on the isle of Rùm killed a healthy, {{convert|7|kg|lb|abbr=on}} red deer calf within a couple of days.<ref name="Love-1983"/> 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 [[domestic goat|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.<ref name=Willgohs/><ref>Marquiss, M., Madders, M., Irvine, J., & Carss, D. N. (2004). ''The impact of White-tailed Eagles on sheep farming on Mull''. Scottish Executive.</ref><ref>Marquiss, M., Madders, M., & Carss, D.N. (2003). ''White-tailed Eagles (Haliaeetus Albicilla) and Lambs (Ovis Aries)''.</ref>

Prey of other animal classes is rarely taken by white-tailed eagles. Particularly, the diversity of [[reptile]]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]]s only two species of toad are known to be taken.<ref name="Love-1983"/><ref name=Mori/><ref name=Samago/><ref name="Sherrod-1978">{{Cite journal|last=Sherrod |first=Steve K. |title=Diets of North American Falconiformes |url=https://sora.unm.edu/sites/default/files/journals/jrr/v012n03-04/p00049-p00121.pdf |journal=Journal of Raptor Research |volume=12 |issue=3/4 |pages=49–121 |year=1978 |s2cid=127093159}}</ref> The Ural mountains is the only region where some diversity of reptile and amphibian species have been reported in their diet.<ref name=Samago/> In only the white-tailed eagles nesting in Hokkaido, they've been known to hunt large [[cephalopod]]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.<ref name=Mori/> White-tailed eagle juveniles have been seen rarely foraging for unidentified [[clam]]s and [[mussel]]s on the [[Rhine]].<ref>Uttendörfer, O. (1952). ''Neue Ergebnisse überdie Ernährung der Greifvögel und Eulen''. Stuttgart & Ludwigsburg: Eugen Ulmer.</ref> However, the miscellaneous shells of marine mussels and snails found in Norway are probably usually consumed secondarily from the stomachs of eiders.<ref name=Willgohs/> An exceptional number of [[insect]]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.<ref name=Vrezec/>

===Interspecies predatory relationships===
[[File:White-tailed Eagle with 2 Buzzards.jpg|thumb|A juvenile (right) being [[Mobbing (animal behavior)|mobbed]] by a pair of [[common buzzard]]s over the [[Canna, Scotland|Isle of Canna]]]]

As the largest eagle in the majority of its distribution, the white-tailed eagle is an [[apex predator]] in its range.<ref name="Love-1983"/><ref name=Salo>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.</ref> In some areas it may compete with other large raptors, especially [[golden eagle]]s. Relations between these two species are complex and variable.<ref name=Whitfield/><ref name=Halley/><ref name=Watson/> 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 favour 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.<ref name=Halley/><ref name=Watson/> 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.<ref name="Love-1983"/><ref name=Halley/> 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.<ref name="Love-1983"/><ref name=Halley/><ref name=Halley2/> 

In many intraguild diurnal raptor assemblages, a slightly smaller, swifter-flying species often dominate their heavier competitors unless size differences become extreme,<ref>Poole, K. G., & Bromley, R. G. (1988). ''Interrelationships within a raptor guild in the central Canadian Arctic''. Canadian Journal of Zoology, 66(10), 2275–2282.</ref><ref>Janes, S. W. (1985). ''Interspecific Interactions Among Grassland and Shrubsteppe Raptors: The Smaller Species Wins. Behavioral interactions and habitat relations among grassland and shrubsteppe raptors'', 7.</ref> to the contrary of [[owl]]s and several other predators which often adhere fairly strictly to a size-based dominance hierarchy.<ref name=Voous>Voous, K.H. 1988. ''Owls of the Northern Hemisphere''. The MIT Press, 0262220350.</ref><ref name=Mikkola>{{cite journal |last1=Mikkola |first1=Heimo |year=1976 |title=Owls killing and killed by other owls and raptors in Europe |journal=British Birds |volume=69 |issue= |pages=144–154 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V69/V69_N04/V69_N04_P144_154_A030.pdf}}</ref> 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.<ref name=Halley/><ref name=Halley2>{{cite journal|last1=Halley |first1=Duncan J. |last2=Gjershaug |first2=Jan Ove |orig-year=1998 |year=2008 |title=Inter-and intra-specific dominance relationships and feeding behaviour of Golden Eagles Aquila chrysaetos and Sea Eagles Haliatetus albicilla at carcasses |journal=Ibis |volume=140 |issue=2 |pages=295–301 |doi=10.1111/j.1474-919X.1998.tb04392.x |s2cid=84810788}}</ref> 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.<ref>Pettersson J. 1977. ''White-tailed Eagle, ''Haliaeetus albicilla'', robbing Golden Eagle, ''Aquila chrysaetos'', of its prey''. Var Fagelvarld, 36: 54.</ref><ref>{{cite news |url= https://www.telegraph.co.uk/earth/wildlife/8206695/Golden-Eagle-surrenders-meal-to-White-Tailed-Eagle.html |archive-url= https://web.archive.org/web/20101219072225/http://www.telegraph.co.uk/earth/wildlife/8206695/Golden-Eagle-surrenders-meal-to-White-Tailed-Eagle.html |url-status= dead |archive-date=19 December 2010 |title=Golden Eagle surrenders meal to White Tailed Eagle |newspaper=The Telegraph |access-date=30 April 2013 |location=London |date=16 December 2010}}</ref><ref>Whitfield, P. (2000). ''Golden Eagle Aquila chrysaetos ecology and conservation issues''. SNH REVIEW, (132).</ref> Some territorial conflicts in Scotland have escalated, albeit rarely, to both eagle species killing the other.<ref name=Watson/> 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.<ref name=Whitfield/><ref name=Halley/><ref name=Halley2/> Notably, in competition in [[North America]], 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.<ref name=Buehler/><ref>{{cite journal |last1=Jorde |first1=Dennis G. |last2=Lingle |first2=Gary R. |title=Kleptoparasitism by Bald Eagles wintering in South-Central Nebraska |journal=Journal of Field Ornithology |volume=59 |issue=2 |pages=183–188 |year =1998 |url=https://sora.unm.edu/sites/default/files/journals/jfo/v059n02/p0183-p0188.pdf}}</ref><ref>Garcelon, D. K. (1988). ''The reintroduction of bald eagles on Santa Catalina Island, California'' (Doctoral dissertation, Humboldt State University).</ref><ref name=Auk85.4.681>{{cite journal|last1=Erskine |first1=Anthony J. |year=1968 |title=Encounters between Bald Eagles and Other Birds in Winter |journal=The Auk |volume=85 |issue=4 |pages=681–683 |doi=10.2307/4083378 |jstor=4083378|doi-access=free }}</ref>
[[File:Haliaetus albicilla 6043 (16702793704).jpg|thumb|left|upright=0.9|White-tailed eagles often steal food opportunistically from other birds, especially fish from [[osprey]]s.]]
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.<ref name="Love-1983"/> For example, in Kazakhstan, white-tailed eagles were recorded to nest in proximity to golden eagles, [[eastern imperial eagle]]s (''Aquila heliaca'') and [[steppe eagle]]s (''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.<ref>Katzner, T. E., Bragin, E. A., Knick, S. T., & Smith, A. T. (2003). ''Coexistence in a multispecies assemblage of eagles in central Asia''. The Condor, 105(3), 538–551.</ref> A more direct effect may be detected on other fish-eating birds, for example recovering numbers of white-tailed eagles in [[Lithuania]] was thought to limit local osprey populations. However, in similar habitats, white storks and [[lesser spotted eagle]]s (''Clanga pomarina'') appeared to not be competitively effected.<ref name=Treinys2>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.</ref> Besides competitive effects, white-tailed eagles may adversely effect ospreys by habitually robbing them of their catches.<ref name=Willgohs/> 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.<ref name="Love-1983"/><ref name=Brown/> 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.<ref>Ladygin, A. (1991). ''Morpho-ecological adaptations in Stellers sea and White-tailed sea eagles, a comparative analysis''. Current Ornithology, 1991. Vol.1. pp. 42–56.</ref><ref>Masterov, V.B. 1992. ''Ecological energetic and interspecific relations between White-tailed and Steller's Sea eagles (''Haliaeetus albicilla'' L., ''Haliaeetus pelagicus'' Pall.) in Lower Amur and Sakhalin''. The materials of Ph.D. work, 157 pp., (In Russian).</ref> Although the Steller's sea eagle may be somewhat favoured 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.<ref>{{cite web |url=http://www.arkive.org/stellers-sea-eagle/haliaeetus-pelagicus/image-G113853.html |title=Steller's sea eagle photo (Haliaeetus pelagicus) – G113853 |website=ARKive.org |publisher=Wildscreen |archive-url=https://web.archive.org/web/20130505070526/http://www.arkive.org/stellers-sea-eagle/haliaeetus-pelagicus/image-G113853.html |archive-date=5 May 2013 |url-status=dead |access-date=21 August 2012}}</ref><ref>{{cite web |url=http://www.nwf.org/News-and-Magazines/National-Wildlife/Birds/Archives/2009/Sea-Eagles.aspx |title=The Secret Lives of Sea Eagles |website=NWF.org |publisher=The National Wildlife Federation |last=Williams |first=Laura |date=12 January 2008 |access-date=21 August 2012 |archive-url=https://web.archive.org/web/20110218095214/http://www.nwf.org/News-and-Magazines/National-Wildlife/Birds/Archives/2009/Sea-Eagles.aspx |archive-date=18 February 2011 |url-status=dead}}</ref><ref>{{cite web |url=http://www.goldenfirstlight.com/keyword/steller's%20sea%20eagle/1/1217921310_H9hW4 |title=Steller's sea eagle photos |website=Golden First Light |last=Golden |first=Laurie |date=21 June 2012 |access-date=21 August 2012}}</ref> 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.<ref name="Sherrod-1978" /><ref name="Stalmaster">Stalmaster, M.V. (1987). ''The Bald Eagle''. Universe Books, New York.</ref><ref>Grubb, T. G. (1995). ''Food habits of bald eagles breeding in the Arizona desert''. The Wilson Bulletin, pp. 258–274.</ref>

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.<ref name="Love-1983"/> 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.<ref name="Love-1983"/><ref name=Bergo>{{cite journal |last1=Bergo |first1=Gunnar |year=1987 |title=Territorial behaviour of Golden Eagles in Western Norway |journal=British Birds |s2cid=54701876 |volume=80 |issue= |pages=361–376 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V80/V80_N08/V80_N08_P361_376_A086.pdf}}</ref><ref>Cheke, A. S. (1964). ''Some Notes On Birds in Eastern Hokkaido''. Tori, 18(83): 175–185.</ref> 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.<ref name="Love-1983"/><ref name=Meinertzhagen/><ref name=Treinys2/> Other accipitrids they are known to have preyed upon, in increasing order of size are the [[Eurasian sparrowhawk]] (''Accipiter nisus''),<ref name=Sulkava/> [[western marsh harrier]] (''Circus aeruginosus''),<ref name=Probst/> [[black kite]] (''Milvus migrans''),<ref name=Mori/> [[European honey-buzzard]] (''Pernis apivorus''),<ref name=Sulkava/> [[common buzzard]] (''Buteo buteo''), [[northern goshawk]],<ref name= Sulkava/> [[red kite]] (''Milvus milvus''),<ref name=Palmer>Palmer, R. S. (Ed.). (1988). ''Handbook of North American Birds Volume VI: Diurnal Raptors (Part 1)''. Yale University Press.</ref> lesser spotted eagle (''Clanga pomarina'')<ref>Dementavičius, D., Rumbutis, S., Vaitkuvienė, D., Dagys, M. & Treinys, R. (2017). ''Does mesopredator Lesser Spotted Eagle suffers breeding costs in a high-density area of the White-tailed Eagle?'' The Collection of Abstracts and Short Notes of the Sea Eagle Conference 2017.</ref> and eastern imperial eagle,<ref name=Palmer /> in addition to osprey.<ref name=Sulkava/> Non-accipitrid raptorial birds, these more likely restricted to fully independent birds due to their less conspicuous nests, known to fall prey to white-tailed eagles include [[Eurasian pygmy owl]] (''Glaucidium passerinum''),<ref name=Voous/> [[boreal owl]] (''Aegolius funereus''),<ref name= Sulkava/> [[Eurasian hobby]] (''Falco subbuteo''),<ref name= Arkadevich/> [[long-eared owl]] (Asio otus),<ref name=Ivanovsky/> [[northern hawk owl]] (''Surnia ulula''),<ref name=Sulkava/> [[short-eared owl]] (''Asio flammeus''),<ref name=Sulkava/> [[peregrine falcon]] (''Falco peregrinus''),<ref name=Sulkava/> [[snowy owl]] (''Bubo scandiacus'')<ref>Golovatin, M.G. & Paskhalny, S.P. (2005). ''Distribution, numbers and ecology of White-tailed Eagle in the north of West Siberia''. Berkut, 14 (1): 59–70.</ref> and [[Eurasian eagle owl]] (''Bubo bubo'').<ref name=Mikkola/> Accipitrid prey size ranges by body mass ranges from {{convert|237|g|oz|abbr=on}} for a sparrowhawk to {{convert|3.13|kg|lb|abbr=on}} in the imperial eagle and that of non-accipitrid raptors ranges from {{convert|58.5|g|oz|abbr=on}} for the pygmy owl to {{convert|2.68|kg|lb|abbr=on}} for the eagle owl and apparently both imperial eagles and eagle owls that were caught were adults.<ref name="CRC"/><ref name=Palmer/><ref name=Voous/><ref>Kirmse, W. (1998). ''Morphometric features characterizing flight properties of palearctic eagles''. Holarctic Birds of Prey, pp. 339–348.</ref> 

White-tailed eagles occasionally prey on mammalian carnivores. [[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).<ref name=Salo/><ref>Salo, P. (2009). ''On lethal and nonlethal impacts of native, alien and intraguild predators-evidence of top-down control''. Section of Ecology, Department of Biology, University of Turku, Finland.</ref> A few species of native [[mustelid]], including [[stoat]]s (''mustela erminea''), [[European polecat]]s (''mustela putorius''), [[pine marten]]s (''Martes martes''), [[sable]]s (''Martes zibellina'') and even [[European otter]]s (''Lutra lutra'') can be taken infrequently.<ref name="Love-1983"/><ref name=Arkadevich>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.</ref><ref name="Sidorovich">Sidorovich, Vadim. Analysis of vertebrate predator-prey community: Studies within the European Forest zone in terrains with transitional mixed forest in Belarus. Tesey, 2011.</ref><ref name="NOVIKOV">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)</ref><ref>Miyoshi, Kazuki, and Seigo Higashi. "Home range and habitat use by the sable Martes zibellina brachyura in a Japanese cool-temperate mixed forest." Ecological Research 20 (2005): 95-101.</ref><ref>Hancox, M. "Some Key Factors in Breeding, Conservation, and Sociology of Otters IUCN Otter Spec." Group Bull 7 (1992): 2-4.</ref> Among [[canid]]s, pups of [[Arctic fox]]es (''Vulpes lagopus'') are the sixth most regular prey species in [[Greenland]],<ref name=Wille/> While adult [[corsac fox]]es (''Vulpes corsac'') are occasionally taken in [[Russia]].<ref>Plaksa, S.A., Yarovenko, Y.A. & Gadzhiev, A.A. Status evaluation of corsac fox (Canidae, Vulpes corsac) population in Dagestan. Arid Ecosyst 3, 85–91 (2013). https://doi.org/10.1134/S207909611302008X</ref> Several [[red fox]]es (''Vulpes vulpes'') was taken or scavenged in [[Norway]] and [[Finland]], and suspected predation on red fox have been reported in [[Belarus]] and [[Slovenia]].<ref name=Willgohs/><ref>Sulkava, Seppo, Risto Tornberg, and Juhani Koivusaari. "Diet of the white-tailed eagle Haliaeetus albicilla in Finland." Ornis Fennica 74.2 (1997): 65-78.</ref><ref name="Sidorovich"/><ref>Vrezec, Al, et al. "Population and ecology of the White-tailed Eagle (Haliaeetus albicilla) and its conservation status in Slovenia." Denisia 27 (2009): 103-114.</ref> White-tailed eagles are also considered predators of [[raccoon dog]]s of all ages, as well as scavenging their carcass.<ref name="NOVIKOV"/><ref>Kowalczyk, Rafał, et al. "Reproduction and mortality of invasive raccoon dogs (Nyctereutes procyonoides) in the Białowieża Primeval Forest (eastern Poland)." Annales Zoologici Fennici. Vol. 46. No. 4. Finnish Zoological and Botanical Publishing Board, 2009.</ref><ref name="Sidorovich"/> Domestic carnivores, including [[cat]]s (''Felis catus'') and small [[dog]]s (''Canis familiaris'') are known to be taken on rare occasions.<ref name=Vrezec/><ref name=Mori/> 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.<ref name=Bannerman>Bannerman, D. A. (1959). ''The birds of the British Isles (Vol. 8)''. Oliver and Boyd.</ref> 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]] (''Pusa sibirica'') pups were taken in Lake Baikal.<ref name="Mlíkovský-2009"/> They are considered a predator even for live [[grey seal]] (''Halichoerus grypus'') pups that weigh {{convert|11.75|kg|lb|abbr=on}} at birth.<ref>{{cite iucn |author=Bowen, D. |date=2016 |title=''Halichoerus grypus'' |volume=2016 |page=e.T9660A45226042 |doi=10.2305/IUCN.UK.2016-1.RLTS.T9660A45226042.en |access-date=19 November 2021}}</ref> Successful attacks on young [[common seal]] (''Phoca vitulina'') weighing up to {{convert|18|-|20|kg|lb|abbr=on}} have been observed.<ref name=Tadeusz/>

As true apex predators, healthy adult white-tailed eagles have no known natural predators.<ref name="Love-1983"/><ref name=Treinys2/> However, there have been reports of eagles losing their lives after accidentally attacking non-prey animals. In one instance, a white-tailed eagle reportedly tried to attack an adult [[common seal]] but was immediately dragged into the water and soon surfaced dying with a broken wing.<ref name=Bannerman/> Similarly, in one anecdote, an eagle drowned while apparently attacking an adult [[harbour porpoise]] (''Phocoena phocoena'').<ref name=Willgohs/>

== Breeding ==
===Courtship and mating===
[[File:Zeearend paar op het vogeleiland-4962007.webm|thumb|A pair of white-tailed eagles around their nest]]
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.<ref name=Ferguson-Lees/> 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.<ref name=Ferguson-Lees/><ref name=Helander2>Helander, B. (1985). ''Reproduction of the white‐tailed sea eagle ''Haliaeetus albicilla'' in Sweden''. Ecography, 8(3), 211–227.</ref> 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 behaviour, of course, peaks.<ref name=Brown/> 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 {{convert|1|to|6|m|ft|abbr=on}} 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.<ref name="Love-1983"/><ref name=vonBlotzheim/><ref name=Helander2/> 

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.<ref name="Love-1983"/><ref>Simmons, R. E., & Mendelsohn, J. M. (1993). ''A critical review of cartwheeling flights of raptors''. Ostrich, 64(1), 13–24.</ref><ref>Debus, S. J. S. (2008). ''Biology and diet of the White-bellied Sea-Eagle Haliaeetus leucogaster breeding in northern inland New South Wales''. Australian Field Ornithology, 25(4), 165.</ref> 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.<ref name=Brown/> In Greenland, recorded pair densities were 0.3–0.6 occupied territories per {{convert|100|km2|sqmi|abbr=on}}.<ref>Hansen, K. (1979). ''Status over bestanden av Havorn ''Haliaeetus albicilla groenlandicus'' Brehm i Grönland i ärene 1972–74''. Danskorn. Foren. Tidskr. 73: 107–130.</ref> In eastern Germany, densities were reported as 1.6–2 pairs per {{convert|100|km2|sqmi|abbr=on}}. Norwegian nests appear at no closer than {{convert|1|-|2|km|mi|abbr=on}}; territory size on Norwegian coasts were reported as roughly {{convert|6|to|9|km2|sqmi|abbr=on}}.<ref name=Willgohs/> Fischer noted 8–9 pairs on the small Norwegian island of [[Nord-Fugløya]] due to its huge seabird colonies, with late summer numbers boosting to 75 eagles, all within an area of only {{convert|22|km2|sqmi|abbr=on}}.<ref name=Fischer2/> Five occupied nests were noted on an {{convert|80|km|mi|abbr=on}} stretch of the Russian [[Yenisei River]].<ref name=Fischer2/> 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.<ref name=Brown/> 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 {{convert|3|km|mi|abbr=on}} 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.<ref name="Love-1983"/><ref name=Willgohs/><ref name=vonBlotzheim/>

===Nest characteristics===
[[File:Haliaeetus albicilla empty nest.jpg|thumb|An unoccupied white-tailed eagle nest in [[Norway]]. Despite the preferable location, it is likely an alternate nest.]]
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.<ref name=Brown/> Access to food is a key consideration in the nest's location in white-tailed eagles. In Germany, 75% of eyries were within {{convert|3|km|mi|abbr=on}} of a lake, although one was {{convert|11|km|mi|abbr=on}} away from any lake though was somewhat closer to the Baltic Sea.<ref name=Oehme>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.</ref> 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 {{convert|150|m|ft|abbr=on}} 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 {{convert|2|to|10|m|ft|abbr=on}} off ground in the main fork of trees, rarely on ample horizontal tree branches.<ref name="Fischer2" /><ref name=Oehme/> 

Tree nest height is partially based on tree species, i.e. in Romania, on [[Populus nigra|black poplars]] (''Populus nigra'') and [[willow]]s nest height would was recorded at {{convert|15|to|25|m|ft|abbr=on}} of the ground but one was on a broken tree at only {{convert|7|m|ft|abbr=on}} 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 [[oak]]s, five in [[Populus alba|white poplars]] (''Populus alba''), two in [[beech]]es and one in a wild [[pear]] tree.<ref name= Bannerman/> Another quote on eyrie height along the Danube was at {{convert|19|to|33|m|ft|abbr=on}} above the ground.<ref name= vonBlotzheim/> Trees used for nests in Hokkaido were often the tallest in a stand, averaging {{convert|2.8|m|ft|abbr=on}} higher than the average tree height in their stand. Tree species preferred here were ''[[Picea glehnii]]'' and ''[[Alnus japonica]]''.<ref>Shiraki, S. (1994). ''Characteristics of white-tailed sea eagle nest sites in Hokkaido, Japan''. Condor, pp. 1003–1008.</ref> Nest height in Hokkaido was similar to that in Europe at {{convert|16.5|to|25|m|ft|abbr=on}} above the ground.<ref name=Mori/> In eastern Germany, among 177 nests, 65% were in mature pines, 22% in [[Fagus sylvatica|copper beech]]es (''Fagus sylvatica''), 8% in [[oak]] with the remainder in [[alder]], [[elm]], [[Populus|poplar]] and [[birch]]. The German eyries ranged in height from {{convert|8|to|30|m|ft|abbr=on}}, averaging {{convert|20|m|ft|abbr=on}}, usually in tallest trees available.<ref name=Oehme/> Nests can be on crags, whether or not trees may be available, depending on regional habitat.<ref name=Brown/> 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.<ref name="Love-1983"/><ref name=Willgohs/><ref name="Ingólfsson"/><ref name=Christensen>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.</ref> Nest height on cliffs can be over {{convert|75|m|ft|abbr=on}} above the nearest flat ground.<ref name=Ferguson-Lees/> 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.<ref name=Brown/> Showing their adaptability, one pair even nested on a [[buoy]] on a Norwegian shipping route.<ref name=Willgohs/>

Nests are usually huge, constructed of sticks and branches, averaging roughly {{convert|1|m|ft|abbr=on}} across and up to {{convert|2|m|ft|abbr=on}} deep, but can be several metres in width & depth, lined variously with moss, greenery, seaweed or wool.<ref name=Ferguson-Lees/> 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.<ref name="Love-1983"/> 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 {{convert|1.5|m|ft|abbr=on}} 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.<ref name=Willgohs/> In tree nests, the average nest diameter is about {{convert|1.5|m|ft|abbr=on}}, with nests in trees tending to be larger, more rigid and stronger. A relatively new four-year-old nest weighed {{convert|240|kg|lb|abbr=on}} and one about twice that age can exceed {{convert|600|kg|lb|abbr=on}} in mass. Some tree nests may range easily up to {{convert|2|m|ft|abbr=on}} in diameter and {{convert|3|m|ft|abbr=on}} deep after many repairs over years, with extreme sizes of perhaps another metre in diameter and depth, or "twice the height of a man".<ref name=Brown/><ref name=Willgohs/><ref name=vonBlotzheim/><ref>Ussher, R. J., & Warren, R. (1900). ''Birds of Ireland''.</ref> Tree nests may be lined with [[lichen]], [[moss]], [[seaweed]], [[fern]]s, [[grass]], [[woodrush]], [[Calluna|heather]] or ''[[Empetrum]]''; many tree nests may be lined with sheep's wool.<ref name="Love-1983"/><ref name=Willgohs/><ref name=Christensen/> 

The male of the pair more often brings nesting branches, while the female takes the primary role in construction.<ref name="Love-1983"/> 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.<ref name=Brown/> Repair to an existing nest can take about 18 days.<ref name="Love-1983"/> White-tailed eagles have also used nests built by other species: [[black kite]], [[common buzzard]], [[common raven]] (''Corvus corax'') and, subsequent to the eagles evicting them, [[osprey]]s and [[red kite]]s. [[Eastern imperial eagle]]s, [[Saker falcon|saker]] (''Falco cherrug'') and [[peregrine falcon]]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.<ref name=Fischer1 /><ref name=vonBlotzheim/> 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.<ref>Deppe, H. J. (1972). ''Einige Verhaltensbeobachtungen an einem Doppelhorst von Seeadler (''Haliaeetus albicilla'') und Wanderfalke (''Falco peregrinus'') in Mecklenburg''. Journal für Ornithologie, 113(4), 440–444.</ref> In Norway, pairs of ravens, peregrines and white-tailed eagles have been known to successfully nest on the same cliff face.<ref name=Willgohs/> Many small species of bird may nest in the immediate area of white-tailed eagle eyries, presumably due to incidental protection: [[Eurasian tree sparrow]] (''Passer montanus''), [[white wagtail]] (''Motacilla alba''), [[Eurasian treecreeper]]s (''Certhia familiaris''), [[common redstart]]s (''Phoenicurus phoenicurus''), [[European crested tit]]s (''Lophophanes cristatus''), [[Eurasian starling]]s and [[stock dove]]s (''Columba oenas'').<ref name=Fischer1 /><ref name=Fischer2/> 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.<ref name= Brown/><ref name= Willgohs/>

===Eggs and incubation===
[[File:Haliaeetus albicilla MWNH 0837.JPG|left|thumb|Egg, Collection [[Museum Wiesbaden]]]]
[[File:Haliaeetus albicilla groenlandicus MHNT.ZOO.2010.11.96.3.jpg|thumb|left|egg, ''Haliaeetus albicilla groenlandicus'' - [[MHNT]]]]
Individual white-tailed eagles tend to be remarkably consistent on egg-laying times from year to year, seemingly regardless of surrounding weather conditions.<ref name="Love-1983"/><ref name=Willgohs/> Egg laying does vary of course by latitude. Historic breeders from [[Israel]] and Iran (where they still usually breed) were reported to lay eggs in January, while in Greece and the lower [[Volga river]] it is during February, in Germany mostly during March and in the subarctic of [[Lapland, Finland]] and northern Russia, to as late as late April to early May.<ref name=Bent/><ref name=Flerov/><ref name="Ingólfsson"/> 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.<ref name="Love-1983"/><ref name=Willgohs/><ref name=Bannerman/> Even near Arctic in Finland, eggs were found as early as 5 March despite ranging often to as late as May.<ref name="Love-1983"/> Younger pairs may nest later on average than older ones.<ref name=Brown/> 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]], as well as in at least Poland, Romania and Norway.<ref name=Willgohs/><ref name=Fischer2/><ref>Witherby, H. F., Jourdain, F. C. R., Ticehurst, N. F., & Tucker, B. W. (1943). ''Handbook of British birds''.</ref> Clutch size in Scotland averages 1.56, while in Norway it is 2.16.<ref name="Love-1983"/><ref name=Willgohs/> 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.<ref name=Brown/> Fresh egg weigh from {{convert|120|to|148|g|oz|abbr=on}}, with an average of approximately {{convert|135|g|oz|abbr=on}} for the first egg and {{convert|124|g|oz|abbr=on}} for the second. If replacement clutch is laid, usually a single egg is laid which may weigh as little as {{convert|112|g|oz|abbr=on}}.<ref name=vonBlotzheim/><ref name=Bannerman/><ref name=Fentzloff>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.</ref> 

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 {{convert|71.8|x|56.2|mm|in|abbr=on}} to the largest in three surveys from Greenland, where they were {{convert|78|x|59.3|mm|in|abbr=on}}. In 54 eggs from Scotland they ranged from {{convert|67.5|to|84.2|mm|in|abbr=on}}, averaging {{convert|75.8|mm|in|abbr=on}}, in height by {{convert|53.4|to|64|mm|in|abbr=on}}, averaging {{convert|58.7|mm|in|abbr=on}}, in width.<ref name=Fischer1 /><ref name=Bent/> In comparison, 90 eggs from mainland Europe ranged from {{convert|66|to|88.2|mm|in|abbr=on}}, averaging {{convert|73.4|mm|in|abbr=on}}, by {{convert|54|to|63.5|mm|in|abbr=on}}, averaging {{convert|57.6|mm|in|abbr=on}}.<ref name=Brown/> Eggs may be compromised quickly by frost and snow in relatively early clutches.<ref name=Brown/> 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.<ref name="Love-1983"/><ref name=Brown/> The female does up to 80–90% of incubation and all known nighttime incubating.<ref name=Brown/> 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.<ref name=Willgohs/> In some cases female may do all the incubation alone, however.<ref name=Brown/> 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.<ref name=Brown/> 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.<ref name=Fischer1/><ref name=Fischer2/>

===Hatching, development and fledgling===
[[File:Haliaeetus albicilla 070525 njg.JPG|thumb|A large nestling in [[Brandenburg]], [[Germany]]]]
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.<ref name="Love-1983"/><ref name=Helander/><ref name=Willgohs/><ref name=vonBlotzheim/> New hatchlings will weigh about {{convert|90|to|100|g|oz|abbr=on}} but in Hokkaido new hatchlings were surprisingly notably heavier at {{convert|110|to|115|g|oz|abbr=on}}.<ref name=Brown /><ref name=Mori/> The sex of nestlings can be identified using field methods, or using [[DNA]].{{sfn|Helander|Hailer|Vilà|2007|p=}} Initially, the hatchlings have a creamy white down which is longest and whitest on the head and often dirty greyish on wings and rump. Before they start walking about the nest, their underside may have several bare patches.<ref name="Love-1983"/> 

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.<ref name=Brown/> The initial down is replaced by a thick woolly coat of longer, coarser greyish 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.<ref name="Love-1983"/> By about 30 days the first feathers poke through the down.<ref name="Love-1983"/> The eaglets can feed themselves starting at 35–40 days.<ref name=Brown/> 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.<ref name="Love-1983"/> Wing flapping begins only when the wings are partially feathered at 42 days.<ref name=Brown/> Around seven weeks of age, the eaglet is more alert and stronger and frequently manipulates sticks and walks more so.<ref name="Love-1983"/> 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.<ref name="Love-1983"/><ref name=Brown/> The eaglets will attempt their first flight at about 70 days and will usually be flying well by about 90 days of age.<ref name=Brown/><ref name=Mori/> Fledgling occurs around mid- to late July in Norway, and about 3–4 weeks later in Russian White Sea.<ref name=Willgohs/><ref name=Flerov/>
[[File:Seeadler 684-2.jpg|thumb|left|Young white-tailed eagles quickly become assured fish predators.]]
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.<ref name=Willgohs/><ref name=Fischer2/> Thereafter, at 14 to 28 days, brooding behaviour by the female gradually declines.<ref name=Brown/> The male may start to brood occasionally around this time period but will not do so at night.<ref name=Willgohs/><ref name=Fischer2/> Females may sit on the nest or shelter the fledglings from rain even 28 days after fledging but usually such behaviour is much reduced.<ref name=Brown/> Chicks may be fed as many as 11 times in 24 hours by the female who usually dismantles prey brought by the male.<ref name="Love-1983"/><ref name=Willgohs/> 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.<ref name=Brown/> As the chicks grow older, favoured food often switches from fish to birds to meet their increasing food requirements as well as prey behaviour as waterfowl may be flightless during [[Plumage|eclipse]].<ref name="Love-1983"/><ref name=Willgohs/> [[Hoarding (animal behavior)|Caches]] are often depleted quickly late into nestling development.<ref name=Willgohs/> 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.<ref name=Brown/> 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.<ref name=Brown/><ref name=Mori/> 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.<ref name="Love-1983"/><ref name=Brown/> In regions where many gather during the winter and spring, such as parts of Scandinavia, communal roosts of immatures can maintain up to at least 30–50 white-tailed eagles usually in trees or steep slopes of offshore islands; during the summer immatures are more likely to occur singly.<ref name=Willgohs/><ref name=DOF17Aug2021/><ref name="JV-2023"/> Sexual maturity is reached at 5–6 years of age.<ref name="Love-1983"/><ref name=Willgohs/>

===Nesting failures and longevity===
[[File:An adult and a juvenile white-tailed eagle (Haliaeetus albicilla) fighting.jpg|thumb|An adult and a juvenile white-tailed eagle fighting]]
Normally, white-tailed eagles succeed in raising one or two young from a clutch of two, and two from a clutch of three.<ref name=Brown/> 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).<ref name=Brown/><ref name=Willgohs/> 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).<ref name="Love-1983"/> Beyond manmade threats to white-tailed eagle nestlings, starvation, and nest collapse are considerable causes of nestling deaths.<ref name="Love-1983"/><ref name=Brown/> Natural threats in the nest may also include [[siblicide]] (or "cainism") wherein the largest nestling behaves aggressively and gradually kill its smaller sibling, which is often consumed.<ref>{{cite journal |last=Simmons |first=Robert E. |orig-year=1988 |year=2008 |title=Offspring quality and the evolution of cainism |journal=Ibis |volume=130 |issue=4 |pages=339–357 |doi=10.1111/j.1474-919X.1988.tb08809.x |s2cid=86569928}}</ref> Despite claims to the contrary,<ref name=Brown/> siblicide in white-tailed eagles does occur in some parts of the range, from Germany to Hokkaido although is certainly rare and highly unusual.<ref name="Love-1983"/><ref name=Mori/><ref>{{cite journal|last=Meyburg |first=Bernd-Ulrich |orig-year=1974 |year=2008 |title=Sibling aggression and mortality among nestling eagles |journal=Ibis |volume=116 |issue=2 |pages=224–228 |doi=10.1111/j.1474-919X.1974.tb00243.x}}</ref><ref>Eriksen, E. (2016). Diet and activity pattern of the white-tailed eagle (Haliaeetus albicilla) under the midnight sun (Master's thesis, Norwegian University of Life Sciences, Ås).</ref> Single cases were reported in the [[White Sea]] 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.<ref name=Flerov/><ref name=ArnoldMaclaren>{{cite journal |last1=Arnold |first1=E. L. |last2=Maclaren |first2=P. I. R. |year=1938 |title=Notes On the Habits and Distribution of the White-Tailed Eagle in N.W. Iceland |journal=British Birds |volume=34 |issue= |pages=4–10 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V34/V34_N01/V34_N01_P004_011_A002.pdf}}</ref> 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]] 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.<ref name=Helander2/><ref name=Meyburg>Meyburg, B. U. (1975). ''Protective management of eagles by reduction of nestling mortality''. World Confer. Birds of Prey, Vienna, pp. 387–391.</ref>

Known natural predators of white-tailed eagle eggs and nestlings include [[red fox]]es, [[marten]]s and [[bear]]s, especially if nesting in overly accessible rock formations, while [[wild boar]]s have been recorded eating eggs and nestlings that have 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 [[crow]]s, [[common raven]]s, and [[western marsh harrier]]s, which are likely to succeed in cases where nest attendance is low or if successful in driving away the parents via fierce mobbing.<ref name="Love-1983"/><ref name=Flerov/><ref name=Fischer2/> Furthermore, Eurasian eagle owls have been reported to prey upon "fairly large" nestlings of white-tailed eagle in nighttime ambushes.<ref name=Mikkola/> Many juveniles do not survive their first years post-independence, but the number significantly increases when well-protected. In the 1970s, an average of 56% [[Bird ringing|ringed]] first-year white-tailed eagles in Norway, Sweden and Greenland were found dead, most often having been shot.<ref name="Hagen,Y. 1976"/><ref name=Helander3>Helander, B. (1975). ''Havsörnen i Sverige''. Fören.</ref><ref>Hansen, K. (1979). ''Population status for the Greenland White-tailed Eagle ''Haliaeetus albicilla groenlandicus'' Brehm covering the years 1972–74''. Dansk orn. Foren. Tidsskr., 73: 107–130.</ref> Following better protection in the Nordic countries and other regions, studies point to a considerably higher survival once fledged. For example, in Norway and Finland, studies showed that, in the 1990s, about 80% or more survived their first two years.<ref>{{cite book | last1=Nygård | first1=T. | last2=Kenward | first2=R.E. | last3=Einvik | first3=K. | year=2000 | chapter=Radio telemetry studies of dispersal and survival in juvenile white-tailed sea eagles Haliaeetus albicilla in Norway | pages=487–497 | editor=R.D. Chancellor | editor2=B.-U. Meyburg | title=Raptors at Risk | publisher=Hancock House Publishers | isbn=0-88839-478-0 }}</ref><ref>{{cite book | last1=Saurola | first1=P. | last2=Stjernberg | first2=T. | last3=Högmander | first3=J. | last4=Koivusaari | first4=J. | last5=Ekblom | first5=H. | last6=Helander | first6=B | year=2003 | chapter=Survival of juvenile and sub-adult Finnish white-tailed eagles in 1991–1999: a preliminary analysis based on resightings of colour-ringed individuals | title=Sea Eagle 2000 | pages=155–167 }}</ref> 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.<ref name=Oehme/> It is estimated that the survival of those that reach adulthood at 70%.<ref name=Cramp/>

The average lifespan has often been based on estimates rather than hard data but varies considerably depending on protection from human persecution. In 1968, it was estimated that the average lifespan for those who reach adulthood was just over 12 years.<ref name=Brown/> Another, more recent estimate of mean lifespan (presumably without persecution) is 21 years.{{sfn|The Nature of Scotland|p=49}} White-tailed eagles in captivity have lived for more than 40 years, though the exact captive longevity record is not known.<ref name="Love-1983"/><ref name=Helander3/><ref>McNicoll, G. (2001). ''Longevity Records: Life Spans of Mammals, Birds, Amphibians, Reptiles, and Fish''. Population and Development Review, 27(2), 381 pp.</ref> A male white-tailed eagle<!--"Skye"--> that was ringed as a chick on the [[Isle of Skye]] in 1994, was recorded on the [[Isle of Mull]] in early 2022 at the advanced age of 28 years old.<ref>{{Cite web |url=https://www.thenational.scot/news/19876266.oldest-white-tailed-sea-eagle-record-found-living-mull-bbc-team/ |title='Oldest white-tailed sea eagle on record' found living on Mull by BBC team |last=Richards |first=Xander |website=[[The National (Scotland)|The National]] |date=26 January 2022 |access-date=25 February 2022 |archive-date=28 January 2022 |archive-url=https://web.archive.org/web/20220128154627/https://www.thenational.scot/news/19876266.oldest-white-tailed-sea-eagle-record-found-living-mull-bbc-team/ |url-status=live}}</ref> His mate, a female white-tailed eagle<!--"Frisa"--> that hatched in 1992 on Mull, will now be 30 years old although her identity has not been confirmed.<ref>{{Cite web |url=https://www.bbc.co.uk/blogs/natureuk/entries/c952d0c6-e967-4ded-a019-887c89efb9a5 |title=A tale of two white-tails: Skye & Frisa |last=Secton |first=Dave |date=18 January 2022 |website=bbc.co.uk |publisher=BBC |archive-date=25 January 2022 |archive-url=https://web.archive.org/web/20220125203228/https://www.bbc.co.uk/blogs/natureuk/entries/c952d0c6-e967-4ded-a019-887c89efb9a5 |url-status=live}}</ref> Comprehensive ringing records from Germany since the 1980s have shown that a typical wild lifespan is up to about 30 years, exceptionally up to about 35.<ref name=DOF23aug2022>{{cite web | title=Vild dansk havørn sætter aldersrekord | url=https://www.dof.dk/om-dof/nyheder?nyhed_id=2092 | date=23 August 2022 | publisher=[[Dansk Ornitologisk Forening]] | access-date=30 July 2023 }}</ref> The oldest known is a female that was ringed as a chick in northern Germany in 1985 and has been part a highly successful breeding pair in southern Denmark since at least 2006. She still paired with the same male at the same location in 2022 and they also fledged a young that year; at 37 years old, she is showing some signs of her age in both colour and feathering.<ref name=DOF23aug2022/>

== Relationship with humans ==
[[File:Haliaeetus albicilla - Museum fur Naturkunde, Berlin - DSC00208.JPG|thumb|upright=0.8|White-tailed eagle skeleton]]

===Extirpations===
The white-tailed eagle formerly bred over much wider area, extending west to much of [[western Europe]] and perhaps south almost continuously in that region to the [[Mediterranean]]. 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]] (mainly remaining in Norway) and some sparse patches of [[eastern Europe]]. They were extinct in the entire [[British Isles]] by the early 1900s.<ref name="Love-1983"/> At one time, the white-tailed eagle bred down to [[Egypt]] in Africa, particularly around [[Lake Manzala]] with individuals wandering rarely to [[Algeria]] and [[Tunisia]]. It is likely that habitat degradation and drying conditions caused the extirpation of the species as all but a vagrant in Egypt.<ref>Maurer, G., Russell, D. G., Woog, F., & Cassey, P. ''The eggs of the extinct Egyptian population of White-tailed Eagle'' Haliaeetus albicilla. Bull. B.O.C. 2010 130(3). 204–210.</ref> Two pairs that nested in the [[Jordan Valley]] ceased to breed, apparently due to [[agrochemical|agricultural chemicals]], in the early 1950s.<ref name="Love-1983"/> The species also once bred in northern [[Syria]] but is not found reliably there even in winter in modern times.<ref name=Cramp/>

===Causes of decline===
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 | caption2  = Adult (top) and immature (below) white-tailed eagle pegged out as decoy by eagle catchers in [[Qinhuangdao]] in late [[Qing dynasty|Qing]] China 
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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, which is largely untrue and game animals for gamekeepers. Therefore, laws were passed to facilitate their destruction.<ref name="Love-1983"/><ref>Murton, R. K. (1971). ''Man and birds (Vol. 51)''. HarperCollins UK.</ref> 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]], [[Lundy]], [[Isle of Man]] and (probably) near [[Plymouth]]; within a couple of decades the species only remained in the [[Lake District]].<ref name=Bannerman/> 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 raised the bounty on eagles to 5 shillings a head by the turn of the 18th century.<ref name="Love-1983"/> Eyries in many coastal sites were found to be easily accessible so that destroying or selling eggs used to be 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.<ref name="Love-1983"/><ref name=Willgohs/><ref name=Christensen/> 

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.<ref name="Love-1983"/><ref name="Ingólfsson"/><ref name=Christensen/> 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 favourable and even when conditions were correct, success at capture as such was low.<ref name="Love-1983"/><ref name=Willgohs/><ref name=Bannerman/> The main driver of declines before firearms and industrialized poisons was habitat alterations.<ref name="Love-1983"/> 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]]. 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.<ref name="Love-1983"/><ref name=Bannerman/> Many [[gamekeeper]]s 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.<ref name="Love-1983"/> Also many white-tailed eagles were poisoned by shepherds who considered it enemy of the flock.<ref>Hudson, W.S. (1906). ''British Birds''. Harper Collins.</ref> 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.<ref name=Bijleveld/> In Norway between 1959 and 1968, an average of 169 eagles were killed annually; with a maximum of 221 in 1961.<ref name=Willgohs/> Around the year 1860, an author estimated that about 400 were being killed annually throughout Germany.<ref name=Bijleveld/> 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.<ref name=Oehme/>

Top predators, especially those that are aquatic and coastal, are vulnerable to exposure to [[DDT]]. Therefore, white-tailed eagles are highly susceptible to this pesticide, as are similar fish eaters, such as [[Eurasian otter|otters]], and bird eaters, such as [[peregrine falcon]]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.<ref name=Newton>Newton, I. (2010). ''Population ecology of raptors''. A&C Black.</ref> In fact, the species was found to have the highest concentration of DDT of any European raptor.<ref>Jensen, S., Johnels, A. G., Olsson, M. & Westermark, T. (1972). ''The avifauna of Sweden as indicators of environmental contamination with mercury and chlorinated hydrocarbons'' . -Proc . XV Int. Ornithol . Congr., Leiden : 455–465</ref> Egg shell thickness was found down from {{convert|0.62|mm|in|abbr=on}} prior to 1935 from 1969 to 1975 down to only {{convert|0.52|mm|in|abbr=on}}, a 16% reduction.<ref>Joutsamo, E., & Koivusaari, J. (1976). ''White-tailed Eagle in Finland 1970–1976''. In Proceedings from the World Wildlife Fund Sea Eagle Symposium, Norway, September 1976.</ref> In Sweden, coastal birds were considerably more effected by DDT than the inland birds of Lapland, Sweden.<ref name=Helander3/> In eastern Germany, where pesticide use was heavy, only 1 out of 28 nesting attempts were known to succeed in 1976.<ref name="Love-1983"/> Overall, about 75% nesting attempts failed in western Germany, Finland and the Swedish Baltic area.<ref name="Love-1983"/> Other environmental pollutants affecting the species include heavy metals which affect individuals through [[bioaccumulation]]. 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.<ref>Oehme, G. (1969). ''Population trends in the white-tailed sea eagle in North Germany''. Peregrine Falcon Populations: Their Biology and Decline, pp. 351–352.</ref><ref>Koeman, J. H., Hadderingh, R. H., & Bijleveld, M. F. I. J. (1972). ''Persistent pollutants in the white-tailed eagle (''Haliaeetus albicilla'') in the Federal Republic of Germany''. Biological Conservation, 4(5), 373–377.</ref> It was estimated that pesticides and metal contaminations reduced the white-tailed eagle population in Hungary from 1957 to 1967 by about 50–60%.<ref name=Bijleveld/> 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.<ref>Kalisńska, E., Salicki, W., & Jackowski, A. (2006). ''Six Trace Metals in White-Tailed Eagle from Northwestern Poland''. Polish Journal of Environmental Studies, 15(5).</ref><ref>Kim, E. Y., Goto, R., Iwata, H., Masuda, Y., Tanabe, S., & Fujita, S. (1999). ''Preliminary survey of lead poisoning of Steller's sea eagle (Haliaeetus pelagicus) and white‐tailed sea eagle (''Haliaeetus albicilla'') in Hokkaido, Japan''. Environmental Toxicology and Chemistry, 18(3), 448–451.</ref><ref>Iwata, H., Watanabe, M., Kim, E. Y., Gotoh, R., Yasunaga, G., Tanabe, S., Masuda, Y. & Fujita, S. (2000). ''Contamination by chlorinated hydrocarbons and lead in Steller’s Sea Eagle and White-tailed Sea Eagle from Hokkaido, Japan''. In First Symposium on Steller’s and White-tailed Sea Eagles in East Asia. Wild Bird Society of Japan, Tokyo (pp. 91–106).</ref> 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.<ref>Kenntner, N., Tataruch, F., & Krone, O. (2001). ''Heavy metals in soft tissue of white‐tailed eagles found dead or moribund in Germany and Austria from 1993 to 2000''. Environmental Toxicology and Chemistry, 20(8), 1831–1837.</ref>

===Conservation measures===
[[File:Haliaeetus albicilla 2 (Martin Mecnarowski).jpg|thumb|upright=0.8|A dark-hued juvenile feeding on the carcass of a large fish, likely that of a large [[Common carp|carp]]]]
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 favour 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.<ref name=Helander3/><ref>Helander, B. (1985). ''Winter feeding as a management tool for white-tailed sea eagles in Sweden''. Conservation studies on raptors. ICBP Technical Publication, (5), 421–427.</ref> Similar winter feeding stations set up in Finland from 1972 to 1978.<ref>Hario, M. (1981). ''Vinterufodring av Havsorn I Finland. In Projekt Hasvorn I Finland och Sverige''. T. Stjernberg (ed.)</ref> 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.<ref>Helander, B., Bignert, A., & Asplund, L. (2008). ''Using raptors as environmental sentinels: monitoring the white-tailed sea eagle ''Haliaeetus albicilla'' in Sweden''. AMBIO: A Journal of the Human Environment, 37(6), 425–431.</ref> 

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.<ref name="Love-1983"/> Since recolonizing [[Schleswig-Holstein]], 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.<ref name="Krüger"/> 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.<ref name=Bijleveld/> In Poland, 78% of forests are state owned and clusters of 10 or more trees are preserved around each white-tailed eagle eyrie.<ref name="Bogucki"/> The Swedish Forest Service limits logging activities to within {{convert|200|m|ft|abbr=on}} of a nest tree which expands to within {{convert|1000|m|ft|abbr=on}} during breeding season; however this acts not as a law but only as an advisory where the eyries are located on private land.<ref name=Helander3/> 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]].<ref name="Love-1983"/><ref name=Flerov/> 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.<ref name=Stjernberg/> 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.<ref name=Movalli>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.</ref><ref>Gómez-Ramírez, P., Shore, R. F., Van Den Brink, N. W., Van Hattum, B., Bustnes, J. O., Duke, G., & Krone, O. (2014). ''An overview of existing raptor contaminant monitoring activities in Europe''. Environment international, 67, 12–21.</ref> Similarly, regulations on lead usage in hunting has been inconsistent in comparison with the stronger efforts to ban lead bullet fragments in [[North America]].<ref>Thomas, V. G., & Guitart, R. (2010). ''Limitations of European Union policy and law for regulating use of lead shot and sinkers: Comparisons with North American regulation''. Environmental Policy and Governance, 20(1), 57–72.</ref> 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.<ref name=Newton/><ref name=Movalli/><ref>Guynup, S., & Safina, B. C. (2012). ''Mercury: Sources in the environment, health effects, and politics''. Blue Oceans Institute, pp. 1–54.</ref>

=== Reintroduction ===
[[File:Haliaeetus albicilla -Loch Portree, Isle of Skye, Scotland -flying-8.jpg|thumb|left|upright|Adult in flight in [[Isle of Skye]], Scotland, from the population of reintroduced birds of Norwegian stock]]
The first attempts at [[reintroduction]] in Scotland were in 1959 in [[Glen Etive]], [[Argyll]] abortively, followed by a better informed but also ultimately unsuccessful attempt on [[Fair Isle]] in 1968.<ref name="Love-1983"/> Successful reintroduction into Scotland did not occur until the 1970s, with the isle of [[Rùm]] in the [[inner Hebrides]] being chosen because of its large size ({{convert|10600|ha|abbr=on}}) with access to the [[Isle of Skye]] (where last native pair known in Britain last bred in 1916) and it is only {{convert|24|km|mi|abbr=on}} from the mainland. Also Rùm hosts large seabird colonies that make for viable prey, including [[Common eider|eider]] (''Somateria mollissima''), [[European shag|shag]] (''Phalacrocorax aristotelis''), [[auk]]s and [[gull]]s; as well as one of the few in Britain of [[manx shearwater]] (''Puffinus puffinus''). Furthermore, mainly as a source of carrion, were a population of around 1500 [[red deer]] and 200 feral [[goat]]s; otters and gulls were also numerous and available to [[Kleptoparasitism|kleptoparasitize]].<ref name="Love-1983"/><ref name="Love-1988"/> 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 (psychology)|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.<ref name="Love-1983"/><ref name="Love-1988"/> The white-tailed eagle now breeds throughout the [[Outer Hebrides|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.<ref>Green, R. E., Pienkowski, M. W., & Love, J. A. (1996). ''Long-term viability of the re-introduced population of the white-tailed eagle ''Haliaeetus albicilla'' in Scotland''. Journal of Applied Ecology, pp. 357–368.</ref> In August 2008, an additional fifteen chicks raised in Norway were released at a secret location in [[Fife]], in expectation of reintroducing the species to the east coast of Scotland as well.<ref name=bbc>{{cite news |url=http://news.bbc.co.uk/1/hi/scotland/edinburgh_and_east/7559305.stm |work=BBC News |title=Birds released in secret location |date=13 August 2008 |access-date=13 August 2008 |archive-url=https://web.archive.org/web/20080814011737/http://news.bbc.co.uk/2/hi/uk_news/scotland/edinburgh_and_east/7559305.stm |archive-date=14 August 2008 |url-status=live}}</ref> 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.<ref name= Evans2>{{cite journal |last1=Evans |first1=Richard J. |last2=Wilson |first2=Jeremy D. |last3=Amar |first3=Arjun |last4=Douse |first4=Andrew |last5=Maclennan |first5=Alison |last6=Ratcliffe  |first6=Norman |last7=Whitfield |first7=D. Philip |display-authors=1 |date=2009 |title=Growth and demography of a re-introduced population of White-tailed Eagles Haliaeetus albicilla |journal=Ibis |volume=151 |issue=2 |pages=244–254 |doi=10.1111/j.1474-919X.2009.00908.x}}</ref> Overall in Britain, there are estimated 36 breeding pairs in 2006 and 40 in 2008.{{sfn|The Nature of Scotland|p=49}}{{sfn|Snow|Perrins|1998|p=48}}<ref name=rspb2>{{cite web |website=[[RSPB]] |url=http://www.rspb.org.uk/supporting/campaigns/birdsofprey/threatened.asp |title=Birds of prey: Which birds are threatened? |date=23 January 2008 |url-status=dead |archive-date=23 November 2008 |archive-url=https://web.archive.org/web/20081123034253/http://www.rspb.org.uk/supporting/campaigns/birdsofprey/threatened.asp}}</ref> Juvenile survival rates are somewhat low overall compared to other areas.<ref name= Evans2/> Reintroduction efforts succeeded in the [[Bohemia]] area of the Czech Republic as well, where the biologists similarly followed the guidelines of guarding of occupied eyries and provision of safe foods.<ref name= Ferguson-Lees/><ref>Ševčík, J. (1987). ''Hnízdění orla mořského ''(Haliaeetus albicilla'') na Třeboňsku.[Nesting of the White-tailed Eagle (''Haliaeetus albicilla'') in the Třeboň region (south Bohemia)]''. Buteo, 2: 41–50.</ref><ref name="Rajchard-2010">{{Cite journal|last1=Rajchard |first1=Josef |last2=Procházka |first2=Jan |last3=Šmahel |first3=Lukáš |year=2010|title=Nest Sites and Reproductive Success of a Restored Population of White-tailed Eagles in the Czech Republic |journal=Journal of Raptor Research |volume=44 |issue=3 |pages=243–246 |doi=10.3356/JRR-09-35.1 |s2cid=86758235}}</ref>

The white-tailed eagle is also being reintroduced to Ireland, where its [[Irish language|Irish]] name of Iolar Mara (sea eagle) reflects its historic association with the island's long coast. The Irish programme was begun in the summer of 2007. Fifteen to twenty young eagles from Norway are being released each spring into the [[Killarney National Park]] 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.<ref name=rte>{{cite news |url=https://www.rte.ie/news/2007/0816/92497-eagles/ |title=Rare eagle reintroduced to Ireland |date=16 August 2007 |newspaper=RTÉ News |archive-url=https://web.archive.org/web/20131030020433/https://www.rte.ie/news/2007/0816/92497-eagles/ |archive-date=30 October 2013 |url-status=live}}</ref> The last pair bred on the coast of Mayo in 1912.<ref name=birdwatchireland>{{cite web |url=http://www.birdwatchireland.ie/IrelandsBirds/Raptors/WhitetailedEagle/tabid/1153/Default.aspx |title=White-tailed Eagle |website=birdwatchireland.ie |access-date=30 April 2012 |archive-url=https://web.archive.org/web/20120501020736/http://www.birdwatchireland.ie/IrelandsBirds/Raptors/WhitetailedEagle/tabid/1153/Default.aspx |archive-date=1 May 2012 |url-status=dead }}</ref> In 2007, a hundred local sheep farmers gathered at Kerry airport to protest against the eagles' arrival. Irish Farming Association Hill Committee chairman Mr O'Leary said he had no doubt the eagles would take lambs.<ref name=Drimnagh>{{cite web |url=http://drimnaghbirdwatch.wordpress.com/2010/03/04/farmers-protest-at-the-arrival-of-the-eagles-in-2007/ |title=Farmers protest at the arrival of the Eagles in 2007 |website=drimnaghbirdwatch.wordpress.com |date=4 March 2010 |access-date=30 May 2011 |archive-url=https://web.archive.org/web/20121114130433/http://drimnaghbirdwatch.wordpress.com/2010/03/04/farmers-protest-at-the-arrival-of-the-eagles-in-2007/ |archive-date=14 November 2012 |url-status=dead}}</ref> 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]]. 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."<ref name=irishtimes>{{cite news |first1=Anne |last1=Lucey |url=https://www.irishtimes.com/news/sea-eagle-death-in-kerry-park-brings-total-to-13-1.660542 |title=Sea eagle death in Kerry park brings total to 13 |newspaper=The Irish Times |date=4 May 2010 |access-date=30 May 2011 |archive-url=https://web.archive.org/web/20160305064532/https://www.irishtimes.com/news/sea-eagle-death-in-kerry-park-brings-total-to-13-1.660542 |archive-date=5 March 2016 |url-status=live}}</ref> The first white-tailed eagle breeding pair since 1912 nested one hundred years later on [[Lough Derg (Shannon)|Lough Derg]] (Loch Deirgeirt), marking a great success for the Irish reintroduction programme.<ref name=irishtimes2>{{cite news |first1=Lorna |last1=Siggins |url=https://www.irishtimes.com/news/sea-eagles-return-to-irish-nest-1.712237 |title=Sea eagles return to Irish nest |newspaper=The Irish Times |date=30 April 2012 |access-date=30 April 2012 |archive-url=https://web.archive.org/web/20151017062514/https://www.irishtimes.com/news/sea-eagles-return-to-irish-nest-1.712237 |archive-date=17 October 2015 |url-status=live}}</ref> 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.<ref name=rte2>{{cite news |url=https://www.rte.ie/news/2013/0508/391034-eaglets-born/ |title=First white-tailed eagles born in Ireland in over 100 years |newspaper=RTÉ News |date=9 May 2013 |access-date=20 May 2013 |archive-url=https://web.archive.org/web/20140104212603/https://www.rte.ie/news/2013/0508/391034-eaglets-born/ |archive-date=4 January 2014 |url-status=live}}</ref> In Spring 2015, five nests hatched chicks in four counties in Ireland – Clare, Cork, Galway and Kerry.<ref name=irishtimes3>{{cite news |url=https://www.irishtimes.com/news/environment/white-tailed-eagle-chicks-hatch-in-five-nests-1.2234643|title=White-tailed eagle chicks hatch in five nests|date=2 June 2015|newspaper=The Irish Times |last=Curran |first=Finnian |archive-url=https://web.archive.org/web/20150719001458/https://www.irishtimes.com/news/environment/white-tailed-eagle-chicks-hatch-in-five-nests-1.2234643 |archive-date=19 July 2015 |url-status=live}}</ref>
[[File:White tailed Eagle from Bridgwater Bay.jpg|thumb|upright|A white tailed eagle was shot in the winter of 1857 at Stolford in [[Bridgwater Bay]] and subsequently preserved for display. It may be seen at the Somerset Heritage Centre (TA2 6SF). It was presented to the county museum by Miss Bailey, the executrix of the owner's will, in 1881.<ref>{{cite journal |journal=The Somerset Archaeological and Natural History Society: Proceedings During the Year 1880 |date=1881 |volume=XXVI |page=86 |title=The Museum: Additions Since the Publications of the Last Volume |url=https://archive.org/details/proceedings26some_0/page/n101/mode/2up}}</ref>]]
In 2019, a reintroduction project on the [[Isle of Wight]] 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.<ref>{{cite news |title=Sea eagles' return to Isle of Wight given go-ahead |work=BBC News |date=2 April 2019 |url=https://www.bbc.co.uk/news/uk-england-hampshire-47792380 |archive-url=https://web.archive.org/web/20190506053524/https://www.bbc.com/news/uk-england-hampshire-47792380 |archive-date=6 May 2019 |url-status=live}}</ref> Following the release of six juveniles on the island in 2019,<ref name=Guardian /> 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.<ref>{{Cite web |date=3 September 2019 |title=Reintroduced White-tailed Eagle tours south-east England |url=https://www.birdguides.com/news/reintroduced-white-tailed-eagle-tours-south-east-england/ |access-date=26 November 2020 |website=BirdGuides |language=en}}</ref>

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]], thus reintroducing the white-tailed eagle to [[East Anglia]]. Up to 60 birds are to be released over a span of 10 years at [[Wild Ken Hill]] in West Norfolk.<ref>{{Cite web |title=From Island to Norfolk as Roy Dennis Wildlife Foundation eagle project expands |url=https://www.countypress.co.uk/news/19291437.white-tailed-eagles-project-expands-norfolk/ |access-date=24 May 2021 |website=Isle of Wight County Press |date=11 May 2021 |language=en}}</ref>

===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.<ref name=rspb2/> In prime habitat in north Europe, distance between breeding pairs can be only {{convert|4|km|mi|abbr=on}} (even as little as {{convert|1|-|2|km|mi|abbr=on|disp=sqbr|1}} locally) such as in Norway, density at one Polish forest were even reported at 6–7 in each square kilometer.<ref name=Ferguson-Lees/> 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]], led by Norway (1,500+ pairs), European Russia (900–1,100), Poland (180–240), Germany (140–150) and Sweden (100–150).<ref name=Ferguson-Lees/> The largest population in Europe is found along the coast of Norway.<ref name="iucn status 19 November 2021" /><ref name=birds.poland.pl>{{cite web |url=http://birds.poland.pl/directory/gallery,White-tailed_Eagle_(Haliaeetus_albicilla),gid,236008,cid,923.htm |title=Polish Birds Directory |website=birds.poland.pl |access-date=30 May 2011 |archive-url=https://web.archive.org/web/20111019142647/http://birds.poland.pl/directory/gallery,White-tailed_Eagle_(Haliaeetus_albicilla),gid,236008,cid,923.htm |archive-date=19 October 2011 |url-status=dead}}</ref> 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.<ref name="Love-1983"/><ref name=Ferguson-Lees/>{{sfn|The Nature of Scotland|p=49}} Even in the early 1980s, Norway maintained a population greater than all other European white-tailed eagle populations combined.<ref name="Love-1983"/> In isolation, Turkey holds merely 10–30 pairs.<ref name=Ferguson-Lees/> Over 500 winter in Japan, mainly Hokkaido, but this island may have only 20 pairs breeding.<ref name=Ferguson-Lees/> 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.<ref name="Radović-2009"/><ref>Literák, I., Mrlík, V., Hovorková, A., Mikulíček, P., Lengyel, J., Št’astný, K., & Dubská, L. (2007). ''Origin and genetic structure of white-tailed sea eagles (''Haliaeetus albicilla'') in the Czech Republic: an analysis of breeding distribution, ringing data and DNA microsatellites''. European Journal of Wildlife Research, 53(3), 195–203.</ref>

Beyond the threat of chemical poisonings, a new threat from [[wind turbine]]s is emerging with significant mortality (considerably in excess of the area's population productivity) occurring at the [[Smøla Wind Farm]] in Norway.<ref name=BirdLife>{{cite web |publisher=BirdLife International |url=http://www.birdlife.org/news/news/2006/02/norway.html |title=Wind farm causes eagle deaths |date=3 February 2006 |archive-url=https://web.archive.org/web/20130922155402/http://www.birdlife.org/news/news/2006/02/norway.html |archive-date=22 September 2013 |url-status=dead}}</ref><ref name=fatbirder>{{cite web |first1=Brian |last1=Unwin |date=4 July 2014 |url=http://www.fatbirder.com/news/index.php?article=779 |website=fatbirder.com |title=Arrivals & Alarms: White-tailed Eagle Imports Endangered by Windfarms |access-date=28 August 2007 |archive-url=https://web.archive.org/web/20070927191005/http://www.fatbirder.com/news/index.php?article=779 |archive-date=27 September 2007 |url-status=dead }}</ref> From 2005 to 2010, 36 birds were killed by wind farm on the isle of [[Smøla]], including four of the 45 recent radio-tagged fledglings. Breeding attempts within {{convert|500|-|1000|m|ft|abbr=on}} of the wind farm were considerably reduced in success. The white-tailed eagles of the region seem to have no behavioural avoidance capabilities, as in many raptors, since the blades are not visible at close range.<ref>Nygård, T., Bevanger, K., Dahl, E. L., Flagstad, Ø., Follestad, A., Hoel, P. L., & Reitan, O. (2010). ''A study of White-tailed Eagle ''Haliaeetus albicilla'' movements and mortality at a wind farm in Norway''. BOU Proceedings-Climate Change and Birds. British Ornithologists’ Union.</ref><ref>Dahl, E. L., Bevanger, K., Nygård, T., Røskaft, E., & Stokke, B. G. (2012). ''Reduced breeding success in white-tailed eagles at Smøla windfarm, western Norway, is caused by mortality and displacement''. Biological Conservation, 145(1), 79–85.</ref><ref>Dahl, E. L., May, R., Hoel, P. L., Bevanger, K., Pedersen, H. C., Røskaft, E., & Stokke, B. G. (2013). ''White‐tailed eagles (''Haliaeetus albicilla'') at the Smøla wind‐power plant, Central Norway, lack behavioural flight responses to wind turbines''. Wildlife Society Bulletin, 37(1), 66–74.</ref> 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.<ref>{{cite journal |last1=Heuck |first1=Christian |last2=Herrmann |first2=Christof |last3=Schabo |first3=Dana G. |last4=Brandl |first4=Roland |last5=Albrecht |first5=Jörg |year=2016 |title=Density-dependent effects on reproductive performance in a recovering population of White-tailed Eagles Haliaeetus albicilla |journal=Ibis |volume=159 |issue=2 |pages=297–310 |doi=10.1111/ibi.12444 |s2cid=89408660 |display-authors=1}}</ref>
[[File:Szélerőművek hatása a madárvilágra.jpg|thumb|left|A white-tailed eagle killed by a wind turbine in Hungary]]
White-tailed eagles have 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]] and Slovakia (scattered pairs in both now with reintroductions factoring in the Czech Republic), Hungary, and Bulgaria.<ref name="iucn status 19 November 2021" /><ref name="Love-1983"/> In Denmark (excluding Greenland where the species never was extirpated as a breeder and there are 150–200 pairs in the south),<ref name=DOFNorthGL/><ref>{{cite web |title=Havørn |url=http://www.natur.gl/pattedyr-og-fugle/fugle/havoern/ |publisher=Grønlands Naturinstitut |date=6 July 2019 |access-date=18 December 2019}}</ref> the breeding population increased from none in 1995 to at least 37 pairs by 2011.<ref name="Ehmsen"/> In 2021, there were more than 150 breeding pairs in Denmark, far surpassing the initial goals of the species' recovery program in the country, which has focussed on better protection and habitat restoration (it has not involved reintroductions). From 1996 when the first pair bred to 2021, altogether more than 1,350 young have fledged.<ref name="DR 2022">{{cite news |title=Havørnene fortsætter med at slå rekord: For 30 år siden var der ingen ynglende par, nu er der over 150 |url=https://www.dr.dk/nyheder/indland/havoernene-fortsaetter-med-slaa-rekord-30-aar-siden-var-der-ingen-ynglende-par-nu-er |publisher=[[DR (broadcaster)|DR]] |date=17 February 2022 |access-date=15 June 2022}}</ref><ref name="DOF 2022">{{cite web |title=Havørnebestand på himmelflugt |url=https://www.dof.dk/om-dof/nyheder?nyhed_id=2046 |publisher=[[Dansk Ornitologisk Forening]] |date=16 February 2022 |access-date=15 June 2022}}</ref> 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.<ref>Horváth, Z. (2009). ''White-tailed Eagle (''Haliaeetus albicilla'') populations in Hungary between 1987–2007''. Denisia, 27: 85–95.</ref> In [[Lithuania]], back in 1985 no pairs were known to have bred but established pairs numbered 90 by 2007 and swelled to 120 by 2011.<ref>Dementavičius, D. (2007). ''White-tailed Eagle (''Haliaeetus albicilla'') in Lithuania: population numbers and trends 1900–2007''. Acta Zoologica Lituanica, 17(4), 281–285.</ref> 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.<ref name=webcam>{{cite web |url=http://www.staatsbosbeheer.nl/actueel/zeearend/default.asp?id=%7B8301F776-F5D0-46A9-8432-99B08D34A3AC%7D |title=zeearend in beeld [sea eagle in the picture] |work=[[Staatsbosbeheer]] |archive-url=https://web.archive.org/web/20070310162650/http://www.staatsbosbeheer.nl/actueel/zeearend/default.asp?id=%7B8301F776-F5D0-46A9-8432-99B08D34A3AC%7D |archive-date=10 March 2007 |url-status=dead}}</ref> In 2010, it turned out that the white-tailed eagle was also breeding in the Zwarte Meer nature district and in the Lauwersmeer area.<ref name=Janssen>{{cite web |first1=Caspar |last1=Janssen |url=http://www.volkskrant.nl/binnenland/zeearend-nestelt-zich-in-nederland~a996141/ |title=Zeearend nestelt zich in Nederland |trans-title=White-tailed eagle nests in the Netherlands |language=nl |publisher=[[De Volkskrant]] |date=24 March 2010 |access-date=30 May 2011}}</ref> There is also a confirmed case of breeding white-tailed eagles in the [[De Biesbosch|Biesbosch]]. Currently (2023), there are over twenty pairs breeding in the Netherlands. They have been spotted at [[Poole Harbour]] in [[Southern England]].<ref>{{Cite web |date=2024-07-23 |title='Huge' birds of prey spotted in Poole Harbour |url=https://www.bournemouthecho.co.uk/news/24467214.photos-pair-white-tailed-eagles-poole-harbour/ |access-date=2024-07-23 |website=Bournemouth Echo |language=en}}</ref>

Studies of [[Microsatellite (genetics)|microsatellite]] and [[mitochondrial DNA]] in white-tailed eagles from north-central Europe have shown that the recovering European population has retained appreciable amounts of [[genetic diversity]], implying low risk of [[inbreeding depression]] (a serious concern in species with low [[population density]]). 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.{{sfn|Hailer|Helander|Folkestad|Ganusevich|2006|p=}}{{sfn|Hailer|2006|p=}}<ref name=Hailer/> As of 2013, the [[IUCN]] estimated the total  population of mature breeding white-tailed eagles at 20,000–49,999 individuals.<ref name="iucn status 19 November 2021" />

== Heraldry ==
[[File:Herb Polski.svg|thumb|upright=0.7|The White-tailed eagle is depicted in the [[Coat of arms of Poland|Polish coat of arms]]]]
[[File:Kumlinge.vapen.svg|thumb|upright=0.7|The white-tailed eagle in the coat of arms of [[Kumlinge]], [[Åland]]]]
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 [[Coat of arms of Poland|Polish coat of arms]].<ref name=birds.poland.pl/> The sea eagle is often blazoned grasping a fish (usually a [[Esox|pike]]) in its talons, distinguishing it from an ordinary eagle.

== Prehistory ==
On [[Orkney]], 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.{{sfn|The Nature of Scotland|p=49}} Cut marks have been found in white-tailed eagle talons in [[Krapina]], suggesting [[Neanderthal]]s' use of [[jewellery]].<ref name="Radovčić-2015">{{cite journal |last1=Radovčić |first1=D. |last2=Sršen |first2=A.O. |last3=Radovčić |first3=J. |last4=Frayer |first4=D.W. |year=2015 |title=Evidence for Neandertal Jewelry: Modified White-Tailed Eagle Claws at Krapina |journal=PLOS ONE |volume=10 |issue=3 e0119802 |doi=10.1371/journal.pone.0119802 |pages=e0119802 |pmid=25760648 |pmc=4356571|bibcode=2015PLoSO..1019802R |doi-access=free}}</ref>

== 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.{{sfn|The Nature of Scotland|p=49}}

==References==
=== Citations ===
{{reflist}}

===Cited works===
* {{cite thesis |last1=Hailer |first1=Frank |year=2006 |title=Conservation genetics of the white-tailed eagle (''Haliaeetus albicilla''). |type=PhD thesis |publisher=Uppsala University |location=Sweden |isbn=978-91-554-6581-0 |oclc=185328184 |url=http://publications.uu.se/abstract.xsql?dbid=6911 |access-date=30 May 2011}}
* {{Cite journal |last1=Hailer |first1=Frank |last2=Gautschi |first2=Barbara |last3=Helander |first3=Björn |year=2005 |title=Development and multiplex PCR amplification of novel microsatellite markers in the White-tailed Sea Eagle, ''Haliaeetus albicilla'' (Aves: Falconiformes, Accipitridae) |journal=Molecular Ecology Notes |volume=5 |issue=4 |pages=938–940 |doi=10.1111/j.1471-8286.2005.01122.x}}
* {{Cite journal |last1=Hailer |first1=F. |last2=Helander |first2=B. |last3=Folkestad |first3=A. O. |last4=Ganusevich |first4=S. A. |last5=Garstad |first5=S. |last6=Hauff |first6=P. |last7=Koren |first7=C. |last8=Nygard |first8=T. |last9=Volke |first9=V. |last10=Vilà |first10=C. |last11=Ellegren |first11=H. |year=2006 |title=Bottlenecked but long-lived: High genetic diversity retained in white-tailed eagles upon recovery from population decline |journal=Biology Letters |volume=2 |issue=2 |pages=316–319 |doi=10.1098/rsbl.2006.0453 |pmc=1618921 |pmid=17148392}}
* {{Cite journal |last1=Hailer |first1=F. |last2=Helander |first2=B. |last3=Folkestad |first3=A. O. |last4=Ganusevich |first4=S. A. |last5=Garstad |first5=S. |last6=Hauff |first6=P. |last7=Koren |first7=C. |last8=Masterov |first8=V. B. |last9=Nygård |first9=T. |last10=Rudnick |first10=J. A. |last11=Saiko |first11=S. |last12=Skarphedinsson |first12=K. |last13=Volke |first13=V. |last14=Wille |first14=F. |last15=Vilà |first15=C. |year=2007 |title=Phylogeography of the white-tailed eagle, a generalist with large dispersal capacity |journal=Journal of Biogeography |volume=34 |issue=7 |pages=1193–1206 |doi=10.1111/j.1365-2699.2007.01697.x |bibcode=2007JBiog..34.1193H |s2cid=56460818}}
* {{Cite journal |last1=Helander |first1=Björn |last2=Hailer |first2=Frank |last3=Vilà |first3=Carles |year=2007 |title=Morphological and genetic sex identification of white-tailed eagle ''Haliaeetus albicilla'' nestlings |journal=Journal of Ornithology |volume=148 |issue=4 |pages=435–442 |doi=10.1007/s10336-007-0156-y |s2cid=907566}}
* {{cite journal |title=Birds of Fortune |url=https://www.scribd.com/doc/296105758/Scottish-National-Heritage-The-Nature-of-Scotland-Spring-2009 |journal=The Nature of Scotland |date=Spring 2009 |oclc=310094759 |ref={{harvid|The Nature of Scotland}} }}
* {{cite book |last1=Snow |first1=David W. |last2=Perrins |first2=Christopher M. |year=1998 |title=The Birds of the Western Palearctic |edition=Concise |publisher=Oxford University Press |isbn=978-0-19-854099-1 |title-link=The Birds of the Western Palearctic}}
* {{cite journal |last1=Wink |first1=M. |last2=Heidrich |first2=P. |last3=Fentzloff |first3=C. |year=1996 |doi=10.1016/S0305-1978(96)00049-X |title=A mtDNA phylogeny of sea eagles (genus ''Haliaeetus'') based on nucleotide sequences of the cytochrome ''b'' gene |journal=Biochemical Systematics and Ecology |volume=24 |issue=7–8 |pages=783–791 |bibcode=1996BioSE..24..783W |url=http://www.uni-heidelberg.de/institute/fak14/ipmb/phazb/pubwink/1996/20_1996.pdf}}. The authors' reservations about using the generalized "2%" rate of [[molecular evolution]] have since proven to be well founded.

== Further reading ==
; Identification
* {{cite journal |last1=Grant |first1=Peter J. |author-link=Peter J. Grant |year=1988 |title=The Co. Kerry Bald Eagle |journal=Twitching |volume=1 |issue=12 |pages=379–380 |quote=describes plumage differences between Bald Eagle and White-tailed Eagle in juvenile plumage}}

; Extinction in Scotland
* {{cite book |last1=Harvie-Brown |first1=J.A. |last2=Buckley |first2=T.E. |year=1892 |title=A Vertebrate Fauna of Argyll and the Inner Hebrides |location=Edinburgh |publisher=David Douglas |pages=104–107}}
* {{cite book |last1=Harvie-Brown |first1=J.A. |last2=Buckley |first2=T.E. |year=1888 |title=A Vertebrate Fauna of the Outer Hebrides |url=https://archive.org/details/bub_gb_fkfPAAAAMAAJ |location=Edinburgh |publisher=David Douglas |pages=[https://archive.org/details/bub_gb_fkfPAAAAMAAJ/page/n228 84]–87}}

== External links ==
{{Commons category|Haliaeetus albicilla}}
{{Wikispecies|Haliaeetus albicilla}}
* [https://web.archive.org/web/20150315033157/http://www.tk.no/vis/direktevideo/reir White-tailed Eagle Webcam - Smøla, Norway]
* [http://www.rspb.org.uk/birds/guide/w/whitetailedeagle/index.asp White-tailed Eagle] at [[RSPB]]: Birds by Name
* [http://www.birdsnetherlands.nl/white%20tailed%20eagle.htm Live webcam nest White-tailed Eagle, Oostvaardersplassen, Netherlands].
* [https://www.flickr.com/search/groups/?q=Haliaeetus%20albicilla&w=42637302%40N00&m=pool Fieldguide page on Flickr]
* [https://web.archive.org/web/20101106084809/http://www.bbc.co.uk/nature/species/White-tailed_Eagle White-tailed Eagles in Scotland]. BBC website.
* {{BirdLife|22695137|Haliaeetus albicilla}}
* {{Avibase|name=Haliaeetus albicilla}}
* {{InternetBirdCollection|white-tailed-sea-eagle-haliaeetus-albicilla|White-tailed Sea-eagle}}
* {{VIREO|White-tailed+eagle}}
* {{Xeno-canto species|Haliaeetus|albicilla|White-tailed eagle}}
* [https://www.youtube.com/watch?v=xQu9kZeQtZ0 Jūras ērgļi (Haliaeetus albicilla) Durbē - LDF tiešraide // White-tailed eagles, Durbe, Latvia]

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[[Category:Haliaeetus|white-tailed eagle]]
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[[Category:Birds of prey of Eurasia]]
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[[Category:Birds described in 1758|white-tailed eagle]]
[[Category:Eagles]]
[[Category:Taxa named by Carl Linnaeus|white-tailed eagle]]
[[Category:Apex predators]]