Steller’s sea eagle (Haliaeetus pelagicus) is a large and beautiful bird of prey.
Like all eagles, it belongs to the family Accipitridae.
These eagles lives in coastal northeastern Asia.
Steller’s sea eagles breed only in eastern Russia, around the Sea of Okhotsk and on the Kamchatka Peninsula. A small number of birds remain in Kamchatka over the winter but the majority fly south to the Kuril Islands, Russia and Hokkaidō, Japan. This species is also occasionally seen in North America, China, and North and South Korea.
Steller’s sea eagle lives near water; on narrow strips of coast, together with forested valleys along lower reaches of rivers. They are generally found at elevations ranging from sea level to approximately 100 meters (328 feet).
These eagles are believed to have a lifespan of about 20 years or more.
Steller’s sea eagle is the largest of all sea eagles and the heaviest known eagle.
Females vary in weight from 6,2 to 9,5 kg (13.5 to 21 lb), while males being rather lighter with a weight range of 4,9 to 6,8 kg (10.8 to 15 lb).
Steller’s sea eagle can range in total length from 85 to 105 cm (2 ft 9 in to 3 ft 5 in), apparently males average about 89 cm (2 ft 11 in) in length, while females average about 100 cm (3 ft 3 in), marginally shorter on average than the harpy eagle and about 65 mm (2.6 in) shorter than the Philippine eagle.
Steller’s sea eagle’s wingspan is one of the largest of any living eagle. The wingspan is from 1.95 to 2.5 m (6 ft 5 in to 8 ft 2 in) and the wing chord measurement is 56 to 68 cm (22 to 27 in).
The mature Steller’s sea eagle is dark brown to black over the majority of its body, with strongly contrasting white on the lesser and median upper-wing coverts, underwing coverts, thighs, under-tail coverts and tail.
They have very large yellow beaks, and sharp, yellow talons.
With forward-facing eyes, Steller’s sea eagle has a wide field of binocular vision. But they can use both monocular and binocular vision, meaning they can use they eyes independently or together depending on what they are looking at.
They are diurnal, meaning they are active during the day and rest during the night.
Steller’s sea eagle mainly feeds on fish. Their favored prey in river habitats are salmon and trout. Among these, pink salmon and chum salmon are reportedly favored, sometimes intensely supplemented by grayling and three-spined stickleback. In addition to fish, they eat crabs, shellfish, squid, small animals, water-dwelling birds, and carrion.
Three types of hunting behaviors have been observed, hunting from a perch, hunting on the wing while circling 6 to 7 meters (20 to 23 feet) above the water, and hunting in shallow water.
Like all raptors, they clamp onto prey with talons as sharp as switchblades and cannot let go until the prey is dead.
Steller’s sea eagles are solitary birds, congregating with others only to breed. However, large numbers can be seen congregating on particularly productive salmon rivers due to an abundant food supply.
Steller’s sea eagles are not extensively known for their voices, but are known to make a deep barking cry, ra-ra-ra-raurau, in aggressive interactions. Their call is similar to the white-tailed eagles but deeper. During the display at the beginning of the breeding season, they have been heard to make calls to each that sound like very loud, deep-voiced gulls.
Steller’s sea eagles are monogamous, they are often seen in breeding pairs throughout the breeding season, usually lasting from February through August. Both males and females secure their own breeding territories early in the season and nest building occurs in February or March. Displaying begins in March and consists of soaring high above the breeding area while calling.
Typically, a pair will maintain two to four nests in one breeding territory and use alternate nests from year to year. Nests are most often built on rocky cliffs or in large trees out of thick branches and can reach a size of 2 meters (6.5 feet) across and 2 to 4 meters (6.5 to 13 feet) thick. The average clutch size is 2 but ranges from 1 to 3. The egg-laying period normally lasts from April through May, and the typical incubation period is 38 days. Eggs hatch between May and June, with fledging taking around 70 days. Chicks leave nests by August or September.
There are no known predators of adult Steller’s sea eagles. Eggs and hatchlings are commonly preyed on by arboreal mammals that gain access to nests, such as martens, and by crows.
Steller’s sea eagle is classified as vulnerable by the International Union for Conservation of Nature (IUCN).
They are legally protected, being classified as a National Treasure in Japan and mostly occurring in protected areas in Russia. However, many threats to their survival persist. These mainly include habitat alteration, industrial pollution, and overfishing, which in turn decrease their prey source.
The current population is estimated at 5,000 and decreasing.
The Steller’s sea eagle was named for Georg Wilhelm Steller, an 18th century zoologist and explorer.
Besides its normal common name, the species has sometimes been referred to as the Pacific eagle or white-shouldered eagle.
In Russian, the eagle has been called morskoi orel (sea eagle), pestryi morskoi orel (mottled sea eagle) or beloplechii orlan (white-shouldered eagle). In Japanese, it is called ō-washi (large eagle or great eagle).