Description
Steller’s sea eagle is one of 8 species of sea and fish eagles in the genus Haliaeetus. The genus includes large to very large eagles with powerful bills and feet, rather short legs, unfeathered tarsi, and often bold color patterns in adults.
The genus is nearly cosmopolitan in distribution. Sea eagles frequent coasts, lakes, and rivers, often scavenge fish, but also take live fish, birds, and mammals.
The adult Steller’s sea eagle is characterized by immense size, dark brown to black plumage with prominent white tail, shoulders, thighs, forehead, and usually crown (except H. p. niger). and a yellow, very deep, strongly arched and compressed beak.
Rump, upper and undertail, and underwing coverts also white. Eye, cere, and legs are yellow, the tail wedge-shaped. Males and females are similar, but females are noticeably larger. Wing length of females up to 680 mm, males 590. Weight of females up to 9 kg, males 6 kg.
First down plumage of nestlings is silky white, the second smoky brown-gray. As in other sea eagles, remiges and retrices of first-year (Juvenal) plumage are longer than adults. Juvenal plumage is uniformly dark brown with white feather bases and light mottling on retrices. Iris is dark brown, legs whitish, beak blackish-brown. Through at least three intermediate plumages, mottling in the tail decreases, body and wing feathering acquires a bronze cast, and the eye and bill lighten in color. Definitive plumage is probably reached in the fifth calendar year (based on fragmentary data from captives). First and intermediate plumages difficult to distinguish from those of the white-tailed sea eagle (H- albicilla) with which it shares all of its breeding range.
Range and Habitat
Steller’s Sea-Eagle: Rare vagrant to the Aleutian and other Alaskan islands. breeds along the north Pacific coast of Asia from Bering Sea coast south to Kamchatka peninsula and north coast of Sea of Okhotsk. Spends winters south to Korea and Japanese island of Hokkaido. Found along coasts and large rivers.
Breeding behaviour
This species’ display is seen in March and consists of soaring above the breeding area calling. Mating may take place on the nestjust prior to egg-laying.
The nests are huge structures, used year after year, built in large trees or occasionally on crags or on smaller trees. Deciduous trees - poplars, birch - and conifers are both used, and the availability of large trees to some extent determines the breeding range. The nests are usually on top of the tree and may be up to eight feet across and from six to twelve feet thick, made of big branches, and up to 100 feet above the ground.
One to three eggs are laid in late April or early May. The earliest young hatch in early June, indicating an incubation period of 38-45 days. Their first feathers appear in early July, and they leave the nest in August, after a fledging period of about 70 days. The whole breeding cycle from display to fledging of the young occupies about six months.
Usually only one young is reared in a nest, but up to three have been successfully reared. The young, after leaving the nest, feed principally on cast up fish and other such offal in the autumn. They acquire full adult plumage at about four years of age, but do not necessarily breeds till later.
Ecology:
It breeds on sea coasts and inland near rivers or lakes, where there are stands of mature trees. During the autumn birds forage along rivers where dead salmon are abundant. During mid-winter, birds in Russia tend to remain on the coast while those wintering in Japan mainly stay near water, but c.35% move to mountainous areas where many forage on deer carcasses
Distribution
Steller’s sea eagle range across eastern Asia. They can be found on the Siberian coast, Kamchatkan peninsula, Japan and Aleutian Islands.
Conservation status
Vulnerable. Total world population is estimated at 5,000 birds and declining. Main threats are felling of old forest and building of hydroelectric plants, over-fishing and lead-poisoning from shot in deer carcasses left by hunters. Recommendations for alleviation of threats include minimizing the impact of industrial development in Russia, establishing artificial feeding sites, encouraging sustainable management of fishing stocks and protection of salmon spawning grounds.
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