The white-tailed or sea eagle (Haliaeetus albicilla) is found mainly in coastal areas and is the UK's largest bird of prey. Adults have a conspicuous pale head and neck, a white tail and yellow beak. Immature birds are much darker brown with a black beak initially and very limited white in the tail. They take around 5 years to reach adult plumage through a series of moults where the plumage become paler brown. Over the same time the beak becomes increasingly yellowish and the tail whiter.
Legal and conservation status
The white-tailed eagle is listed on Annex I of the EC Birds Directive and is specially protected under the Wildlife and Countryside Act 1981, as amended.
Under the IUCN conservation criteria the species has moved from Threatened in 1988 to Least Concern currently. This has been a result of conservation efforts for the species primarily across Europe including the successful reintroduction to Scotland.
It is a high profile species which can be used in raising biodiversity issues more broadly, including specific management issues such as persecution and livestock conflict.
Habitat, distribution and abundance
The species was reintroduced to Scotland from 1975. There have been three releases of young birds sourced from Norway, on Rum from 1975-1985; in Wester Ross 1993-1998; and most recently in Fife from 2007-2013. There are no further plans to release more birds. The first successful breeding was on Mull and a self-sustaining population now mainly comprising wild bred Scottish birds has formed on the west coast of Scotland.
Most of the west coast white-tailed eagle population (which numbered 79 pairs in 2013) is now found on Mull, Skye, Small Isles and the Outer Hebrides. It continues to spread its range with some pairs on the West Highland and Argyll mainland and expansion more widely in the Inner Hebrides. The Fife release birds are just reaching breeding age and the first successful nesting in eastern Scotland for around 200 years occurred in 2013. The Fife release birds and young west coast birds wander widely and have occurred throughout the Highlands and along the east coast.
It is mainly a coastal species, but it also occurs in upland habitats and is found near rivers and large lakes. In Europe and Russia, these may be several hundred miles inland. Wintering areas are similar to the breeding habitats.
The European breeding population is approximately 50% of the global population and has increased notably since 1970. The largest populations are found in Norway (3500-4000 pairs) and Russia, with the species occurring from Greenland to eastern Russia and China. The global population has been estimated at approximately 40,000 birds.
Sea eagles feed on a wide range of prey items, including fish, hares, rabbits, ducks and seabirds, as well as scavenging for carrion especially during the winter months. In Scotland there has been concern expressed about the species taking lambs, and whilst they can take lambs two studies on Mull and in Wester Ross have shown that this is generally at low levels.
In recognition of eagles taking some lambs SNH does operate a sea eagle management scheme.
Nests in Scotland are mostly built in trees, where available but crags and cliffs are also used. These structures can huge and are either used in successive years or alternated with other sites in the territory. Two, occasionally three eggs are laid in March, though sometimes as late as April, with chicks fledging in late July or August. Breeding usually occurs from four or five years old, but territory establishment may be earlier.
History of decline, contributory factors and current threats
In the 19th century over 100 eyries were known from Britain, with birds breeding in Scotland, England and the Isle of Man, and 50 in Ireland. However, following prolonged persecution in the early 19th century, it became extinct in the UK with the last bird shot on Shetland in 1916. Habitat loss was not a factor.
In western Europe, numbers also declined dramatically and its range contracted during the 19th and first half of the 20th centuries due mainly to persecution but also to environmental pollution (e.g. mercury, organochlorines). This trend has been in reverse in the north-west of the range since the 1970s.
Globally, current threats include loss and degradation of wetlands, increasing human disturbance, indiscriminate use of poisons, collisions with wind turbines and overhead wires; reduced availability of suitable habitat, and susceptibility to environmental pollution leading to reduced breeding success.
The 'Species Lead' at Scottish Natural Heritage
Andrew.Stevenson@snh.gov.uk Tel 01878 710381
Last updated on Friday 27th November 2015 at 09:51 AM. Click here to comment on this page