The White-tailed eagle is one of the largest living birds of prey. It is sometimes considered the fourth largest eagle in the world and is on average the fourth heaviest eagle in the world. White-tailed eagles usually live most of the year near large bodies of open water and require an abundant food supply and old-growth trees or ample sea cliffs for nesting. They are considered a close cousin of the Bald eagle, which occupies a similar niche in North America. The adult White-tailed eagle is a greyish mid-brown color overall. Contrasting with the rest of the plumage in the adult are a clearly paler looking head, neck and upper breast which is most often a buffy hue. The brownish hue of the adult overall makes the somewhat wedge-shaped white tail stand out in contrast. All the bare parts of their body on adults are yellow in color, including the bill, cere, feet, and eyes.
White-tailed eagles are widely distributed in northern Europe and northern Asia. They breed as far west as Greenland and Iceland across to as far east in Hokkaido, Japan. These birds live in varied habitat but usually are closely associated with water and generally occur in lowland areas. Especially in winter, many White-tailed eagles often frequent low coastal spots, estuaries and coastal marshes. Inland, birds usually require secluded woods, forested areas or groups of trees with tall mature trees and access to freshwater wetlands such as lakes, river systems, marshes or extensive, low-disturbance farmland.
White-tailed eagles are diurnal and spend much of their day perched on trees or crags, and may often not move for hours. 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. While a relatively gregarious raptor, White-tailed eagles are territorial and any intrusion often provokes vigorously fighting, in which either combatant can even die. White-tailed eagles may be considered partial migrants. They seldom migrate in the western part of their range, and eagles that breed as far north as Greenland, Iceland and coastal Norway do not move at all for winter. During winter, migrating White-tailed eagles tend to become gregarious, especially younger juvenile birds. Many such groups can contain up to 10 birds and, in areas near large breeding populations - at least 30-40 individuals. White-tailed eagles are powerful predators and hunt mostly from perches, in a “sit-and-wait” style, usually from a prominent tree perch. Fish is usually grabbed in a shallow dive after a short distance flight from a perch, usually with the eagles only getting their feet wet. At times they will also fish by wading into shallows, often from shores or gravel islands. When it comes to non-fish prey, White-tailed eagles often hunt by flying low over sea coast or lake shore and attempt to surprise victims. White-tailed eagles become very vocal during the breeding season. The male call is gri-gri-gri or krick-krick-krick, while the female is a deeper gra-gra-gra-gra or krau-krau-krau-krau. Often pairs will duet during early spring, in flight or from a perch. Alarm calls tend to be 3-4 short, loud klee or klek notes.
White-tailed eagles are monogamous and pairs mate for life. The breeding season occurs from January to July in the south of their range, and from April to September in the northern part of their range. Pairs 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. White-tailed eagles usually nest in large trees and nests may be in a high main fork, on the canopy or a large side branch. Nests are usually huge, constructed of sticks and branches, averaging roughly 1 m (3.3 ft) across and up to 2 m (6.6 ft) deep, lined variously with moss, greenery, seaweed or wool. The female lays 2 broad oval shape and dull white in color eggs which she incubates between 38 and 42 days. Hatchlings have a creamy white down which is longest and whitest on the head and often dirty grayish on wings and rump. They are able to move around the nest 10 days after hatching and fledge at 70-80 days of age. They become independent 1 or 2 months later and reach reproductive maturity at 5 to 6 years of age.
For many years White-tailed eagles have been threatened mainly due to human activities. These have included habitat alterations and destruction of wetlands, about a hundred years of systematic persecution by humans followed by inadvertent poisonings and epidemics of nesting failures due to various manmade chemical pesticides and organic compounds, which have threatened eagles since roughly the 1950s and continue to be a potential concern. Due to this, White-tailed eagles were considered endangered or extinct in several countries. These beautiful birds still suffer from illegal persecution by gamebird shooting and egg thieves, habitat loss, deforestation, pollution, accidental poisoning, and collision with wind generators and wind turbines.
According to the IUCN Red List, the total White-tailed eagle population size is around 20,000-49,999 mature individuals. In Europe, the breeding population consists of 9,000-12,300 breeding pairs, equating to 17,900-24,500 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are increasing.