One of the world’s largest birds of prey, it is also known as Steller’s Fish Eagle, the White Shouldered Eagle and a Pacific Sea Eagle. The bird is monotypic meaning there are no subspecies.
Steller’s Fish Eagle, White Shouldered Eagle, Pacific Sea Eagle
One of the most striking things about the Steller’s sea-eagle is the size of its bright yellow coloured bill which is huge, robust and rounded into a vicious hook shape. The nostrils are also large and prominent. The bird is predominantly black or blackish brown above and below with contrasting bright white tail, rump and leg feathers. The shoulders and leading edge of the wings are white and there is a small white patch on the forehead just above the base of the upper mandible. The eyes are yellow as is the eye ring (the area of skin immediately surrounding the eye). Feet are also yellow with sharp hooked dark grey coloured talons. The adult female resembles the male apart from her size which is much larger.
There is an alternative colour morph to the adult Steller’s sea-eagle where the adult bird is black all over apart from a white tail. Although this colour variant is less common, it was also once thought to belong to a subspecies of the nominate.
Juvenile birds appear more blackish brown than black, with grey streaks across the head and breast and dark mottling on a white tail. The beak and feet, like the adult, are yellow.
Upon hatching, chicks have white downy feathers which change to a dirty greyish brown within a week or two.
Steller’s Sea-Eagle walking on the ground
The Steller’s sea-eagle is one of the largest raptors on the planet with a body length from the head to the tip of the tail at just over a metre or 39 inches. The wingspan of an adult can reach 2.5 metres which equates to over 8 feet in length. The plumage and large bill also helps to emphasise the size of this magnificent predator.
Adult and juvenile Steller’s Sea-Eagle next to one another
Adult females are larger than males and can reach a maximum weight of 9.5 kilos which is 21 pounds and it is thus one of the world’s heaviest eagles. The average adult male weighs between 5 and 6 kilos.
Steller’s Sea-Eagle hunting for fish in the sea
Its huge wings and strong legs and talons enable the Steller’s sea-eagle to carry prey up to 7 kilos (in excess of 15 pounds). Considering that an adult male sea-eagle weighs a maximum of 6 kilos this indicates the bird’s incredible strength allowing it to grab a live struggling fish from the water and fly off.
This particular eagle survives mainly on a diet of fish and as such its feet and talons (hooked claws) are smaller than some raptors with a diet of mainly birds and mammals. The toes are shorter than land eagles but very strong and the underside of the feet have ridges which, combined with the overly curved claws, are perfectly designed to hold on to a large, slippery struggling fish.
Close up of Steller’s Sea-Eagle talons
Belonging to the family Accipitridae, the scientific name for the Steller’s sea-eagle is ‘Haliaeetus pelagicus’ which is derived from ancient Greek. The first word is split in two with ‘Hali’ meaning ‘at sea’ and the remainder of the word meaning ‘eagle’. Pelagicus indicates ‘open sea or ocean’.
Generally considered solitary birds, they will on occasion come together in flocks particularly during seasonal salmon runs when food is in abundance. They are particularly fierce hunters and tend to stick to their own breeding areas. During migration they will either fly totally alone or if in a small group they will often remain hundreds of metres apart.
Juvenile Steller’s Sea-Eagle
It is unusual for a full brood of chicks, normally no more than three, to reach adulthood, with generally only one of the clutch surviving to become a breeding adult. The average lifespan of the Steller’s sea-eagle in the wild is twenty years although this can be extended in captivity.
Not only are these birds considered to be Rare they are also classified by the International Union for Conservation of Nature (IUCN) as being on their Red List and are Globally Threatened and Vulnerable. In the most recent estimates it is believed that worldwide there are approximately 5,000 birds which includes up to 2,000 breeding pairs and with the population overall being in decline.
Steller’s Sea-Eagle stood on the ground
The sea-eagle’s diet comprises predominantly of fish and in particular salmon and trout. They will not necessarily just prey on live fish but will also scavenge for dead fish and even steal from other birds. Where fish are not available, they will prey on small sea birds and mammals. Generally, they feed by catching live fish in their talons, diving down to the water’s surface feet first as their prey swims by.
Steller’s sea-eagles are monogamous meaning they have only one mate at a time and they normally establish a long lasting bond. If one partner loses another it will generally seek a second mate.
A pair of Steller’s Sea-Eagle in flight
Breeding pairs will often build a number of large heavy nests close to water on rocky outcrops or high up in the forks of trees, but they will raise their chicks in only one nest. The same adults may visit the same nests year after year during subsequent breeding seasons. Nests are constructed from sticks and twigs and are made or repaired (if using nests from a previous year) during the months of February and March.
The adult breeding female produces one clutch of one to three eggs annually, normally just the two, between the months of April and May. The eggs are incubated for between 38 to 45 days. Infant mortality due to falls from the nest or disease often means only one chick per season will survive. Young fledge around ten weeks after hatching.
Steller’s sea-eagle eggs are a greenish white and are medium to large in size weighing 5.6 ounces (160g) which is slightly larger than a goose egg.
Steller’s Sea-Eagle taking off with caught fish
Generally regarded as silent birds, their calls are more frequent during the breeding season when their song is similar to a large gull’s ‘kyow – kyow’ sound or alternatively, when feeding or roosting outside the breeding season it consists of a raucous deep barking noise, ‘kra – kra – kra’.
Steller's Sea Eagle Call
Andrew Spencer, XC160957. Accessible at www.xeno-canto.org/160957.
Steller’s sea-eagles live in an area of the Palearctic in the northeast corner of Russia, on its Pacific east coast, predominantly along the Kamchatka Peninsula, the western area of the Bering Sea and the Sea of Okhotsk which lies between the east coast of the Russian mainland and the west coast of the Kamchatka Peninsula.
Steller’s Sea-Eagle chick
Heavily dependent upon a fish diet influences where the Steller’s sea-eagle lives which is either along sea cliffs or in mature forested valleys overlooking richly stocked salmon and trout rivers.
Unless you are particularly adventurous you are most likely to come across a Steller’s sea-eagle at a zoo or wildlife park! As a resident breeder in the Russian north east, predominantly along the Kamchatka Peninsula, their chosen domain may not be easily accessible.
Steller’s Sea-Eagle coming in to land
Not all of this species migrates, although the majority do and do so at a time which is dependent upon the availability of food stocks and the conditions of the ice across the breeding grounds. Some simply move away from the coast and settle on the ice sheets close to open water. Those birds that do migrate during the winter months travel south to Russia’s Kuri Islands, Japan’s northernmost land mass Hokkaido, and Korea. Very occasionally vagrant birds find their way across the Bering Straits into Alaska.
Europe’s smallest eagle, the booted eagle, otherwise known as the Booted Hawk Eagle, prefers the warmer climes of southern Europe and south central Asia and whilst not threatened globally, its population within Europe is showing signs of decline.
A member of the sub-family of booted eagles due to its feather covered legs and named after the famous Italian ornithologist Franco Andrea Bonelli, the species is considered endangered across Europe but secure elsewhere within its range.
European Honey Buzzard
The European Honey-Buzzard, which is monotypic, is classified as a bird of prey and is one of six species of Honey-Buzzards from the family Accipitridae, which also includes Kites, Vultures, Harriers, Hawks and Eagles.