White-tailed eagle

Latin Haliaetus albicilla (L.)
Estonian Merikotkas

Also known as: sea eagle, white-tailed sea-eagle, ern or erne, grey sea eagle, Eurasian sea eagle

Status in Estonia

Breeding, migratory and wintering bird.

Description

The white-tailed eagle is very large with long, wide wings, the tips of which are ‘fingered’. A short blunt-wedged tail, a long neck and a powerful beak give it a distinctive flight appearance. Adults are brown with a lighter yellowish brown head and neck. Some of the wing coverts as well as the top of the back and shoulder feathers, have yellow tips, giving the bird a slightly mottled appearance. The beak is yellow, while the tail is either fully white or has brown patches on the base or tip. A juvenile bird’s plumage might be equally fresh or weathered. The secondaries are longer than those of an adult bird, giving the wing a ‘bulging’ edge; the tail is longer and less wedged at the tip. The head, neck and body are dark brown, with broad black tips on the feathers of the breast, abdomen, back and upper portion of the wings; the little coverts are the darkest. Tail feathers are dark with a light centre and when the tail is retracted, they can appear completely dark. The beak is dark.

Size

Body length 76–94 cm, wingspan 190–240 cm, male body mass 3.9–4.2 kg, female body mass 4–6 kg.

Similar species

Lesser spotted eagle, greater spotted eagle, golden eagle.

Distribution

The distribution area ranges from Europe to North Asia, India, China, Japan and Greenland. It breeds throughout Northern, Central and Eastern Europe. It nests only at a few breeding sites in Estonia.

Population

Estonia has 290–330 breeding pairs.

Occurrence in Estonia

Sedentary bird. Adult birds tend to stay near their nests all year, whereas young birds tend to migrate south in the autumn, between October and November. The wintering population is estimated at 1000–1500 individuals.

Diet

It feeds on waterfowl, aquatic animals and their young as well as sick and dead fish and is an expert predator of waterfowl nests. In the winter, it also targets weaker deer, rabbits and foxes. Carcasses, particularly seal carcasses washed ashore on the beach, play a significant role in their diet.

Habitat

It prefers habitats near water bodies, primarily very old spruce-mixed forests and pine forests. Nests are being increasingly built on preserved trees in clear-cut forests, which is most likely due to a lack of good habitats and conspecific colonisation.

 Nesting

Pine is the most common nesting tree, followed by aspen in its absence. A nest site that has been in use for a long time typically has multiple nests. The white-tailed eagle nest is always elevated, with open access. In early April, the female bird lays two eggs, which she incubates for 35 days. Most of the time, only one of the chicks grows up. This is due to cannibalism among the chicks inside the nest as well as fights, which usually results in the weaker bird falling out of the nest. The chicks start to eat food brought by the parents at the age of 5–6 weeks and they leave the nest at the age of two months. The brood stays together until autumn.

Conservation status and protection

It belongs to the protected species of category I. Protecting habitats, particularly nesting areas, is the most important measure to protect the species. It is very sensitive to disturbance during nesting, particularly during incubation and raising the young; therefore, peace and quiet must be ensured in nesting areas. As a top predator, environmental pollutants threaten the white-tailed eagle greatly. One significant factor is toxic lead ammunition entering their body via diet.

Distribution and population in Lääne County

The sea eagle is a bird of prey that is difficult to stay away from before leaving Matsalu or Haapsalu Bay. When you arrive at the bay and look at the larger rocks, you are likely to see a sea eagle sitting on one of them. In Matsalu, white-tailed eagles are commonly observed in Haeska, Keemu and Põgari as well as Haapsalu’s Tagalaht Bay and Saunja Bay inside the Silma Nature Reserve.
In winter, when the inner bays freeze, wintering white-tailed eagles in Lääne County head to coastal areas with open water and resting waterfowl.