Stellers Sea Eagle (Haliaeetus pelagicus)

Stellers Sea Eagle

[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Haliaeetus pelagicus | [authority] Pallas, 1811 | [UK] Stellers Sea Eagle | [FR] Pygargue empereur | [DE] Riesen-Seeadler | [ES] Pigargo gigante | [NL] Stellers Zeearend

Subspecies

Monotypic species

Genus

Members of the genus Haliaeetus are large to very large eagles, with long, broad wings and medium to short rounded or wedge-shaped tails. The bill is large, strong and compressed. The legs are short and the toes and talons powerfully developed

Physical charateristics

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.

Listen to the sound of Stellers Sea Eagle

[audio:http://www.planetofbirds.com/MASTER/ACCIPITRIFORMES/Accipitridae/sounds/Stellers Sea Eagle.mp3]

Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 195 cm wingspan max.: 230 cm
size min.: 85 cm size max.: 94 cm
incubation min.: 38 days incubation max.: 45 days
fledging min.: 65 days fledging max.: 75 days
broods: 1   eggs min.: 1  
      eggs max.: 3  

Range

Eurasia : Northeast. Haliaeetus pelagicus breeds on the Kamchatka peninsula, the coastal area around the Sea of Okhotsk, the lower reaches of the Amur river (south to the Gorin river) and on northern Sakhalin and Shantar, Russia. A few hundred winter in Kamchatka and the coast of Okhotsk, but most (c.2,000) winter in the southern Kuril islands and Hokkaido, Japan. It is an uncommon winter visitor to north-eastern China, North Korea and South Korea. Its population is estimated at c.5,000 birds and declining

Habitat

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

Reproduction

The breeding period varies from region to region, depending on climate and food availability. On Kamchatka, birds begin drifting from wintering to breeding areas in late February. Nest building begins in late February and early March. Copulation occurs on the nest, and first clutches appear in mid April, occasionally earlier. The egg-laying period continues through late May. The incubation period is unknown, but lasts longer than 34 days. Judging from observed size differences in nestlings, incubation begins with the first egg. Hatching occurs between mid May and mid June. Clutches consists of 1-3 eggs, usually 2. Young fledge in August or early September.
Nests are always found near the mouths of rivers, in river valleys, along sea coasts, or on lakes. Nesting is most common in the coastal zone, where rocky shorelines, timbered river valleys, bays, and inlets are preferred. In the interior, nesting occurs less frequently in river valleys and on lakes. On Kamchatka, park-like stands ofErmann’s birch (Betula ermani) and floodplain alder-willow-poplar forests (Ainus. Salix. Populus spp.) are preferred. On the east coast, nests are usually within 30 km of the coast, but a few are 50 km or more inland. On the west coast, many pairs nest 50-80 km from the sea. Elsewhere in the range, nests on major rivers may be 100 km or more inland. Throughout the range, nests usually are in trees and occasionally on cliffs. On Kamchatka, nests are built most often in poplar and birch. All nests in the lower Amur and most on the Sea of Okhotsk and Sakhalin Island are in larches (Larix spp). Nests are typically in the tops of large, mature trees, usually with a dead top. Less often nests are constructed in healthy trees. Nests may be 15-20 m from the ground. Nests are often used for several years in succession, but alternate nests are often built, usually within 900 m of the previous nest. Nests are bulky, constucted of thick branches and twigs, and may reach 2 m in diameter. On one occasion, 2 occupied nests were only 100 m apart.
Breeding success appears to be poor. In any given year on Kamchatka, 45-67% of eggs produced will fail to produce young to fledging, and up to 27% of nestlings will be lost. Failed nesting attempts occur most often due to predation (sable and ermine) and collapsing nests. No nests with 3 fledging-age young have been recorded. All of the breeding range is shared with H. albicilla. Prey and habitat preferences of both species are the same, but on Kamchatka the congener predominates in places where H. pelagicus is rare or sporadic. Where the two species do occur together, H. pelagicus. the larger of the two, seems to accept the former’s presence.

Feeding habits

The diet consists principally of salmon (family Salmonidae). taken both living and dead. The species’ distribution and seasonal appearances are dictated largely by the availability of the salmon supply. The remainder of the diet is highly variable and important only when the principal food supply is scarce. In summer and autumn, the lakes, rivers, and streams containing salmon runs, together with the coastal areas, form the main feeding grounds. Thus, nests in Kamchatka invariably occur near spawning waters of salmon, and communal feeding is common. At the height of the spawing period (August-September), feeding aggregations reach their peak. On Kamchatka, aggregations of 700 birds have been reported, but much smaller groups are more common. During this period, young in the nest are fed on fish 20-30 cm long. On average, food is brought to the nest 2-3 times a day. In summer, spent fish are taken after spawning. In autumn, dead fish are typically taken.
Three hunting techniques and pirating have been observed. Most often, eagles hunt from a perch in a tree or rocky ledge 5-30 m above the water. When prey is spotted, the bird dives from its perch. Eagles may also hunt on the wing, while circling 6-7 m above the water. Again, prey is captured by diving. Eagles sometimes hunt by standing in shallow water on a sandbank, spit, or ice-flow, grabbing passing fish. Where feeding occurs in groups, kleptoparasitism is common. Kleptoparasitism is most beneficial in procuring food during periods of food abundance and in large feeding aggregations. Immatures use kleptoparasitism as much as adults, but are attacked more often by adults than birds of similar age. Adults appear to benefit most from this behavior. The bold color patterns of adults may be an important signal influencing the formation of feeding groups. Outside the breeding period, birds probably roost communally near their feeding sites.
On the lower reaches of the Amur River, summer diet consists of about 80% fish, 10% birds, and 5% mammals. Invertebrates (crabs, sea urchins, mussels, and squid) washed up on shore are also eaten. Along coasts, invertebrates and carrion (e.g., seals and sea lions) probably form a greater part of the diet of young birds. On Kamchatka, prior to the arrival of salmon, ducks and gulls may constitute 50-70% of the food fed to nestlings. After spawning, salmon returning to the sea may also provide an important food source up to the onset of winter. Eagles overwintering in Kamchatka take hares, ermine, sable, and fox (sometimes from the traps of commercial hunters). During winter, H. albicilla and golden eagles (Aquila chrysaetos) may also occur in feeding groups. On Hokkaido, eagles are attracted by abundant cod which peak in the Rausu Sea and Nemuro Straits in February. This resource supports an important commercial fishery which in turn helps to support eagles. In February, the commercial catch can reach 1,250 tons offish daily. If only 0.5% of the catch escapes or slips into the water, enough food becomes available to feed thousands more eagles than are gathered.

Video Stellers Sea Eagle

httpv://www.youtube.com/watch?v=6vQVqJ2Fd_0

copyright: Eugene Potapov


Conservation

This species has a small, declining population as a result of habitat degradation, pollution, poisoning by lead shot, and over-fishing. It therefore qualifies as Vulnerable.
In Russia, it is threatened by habitat alteration during the development of hydroelectric power projects, proposed large-scale coastal and offshore developments for the petrochemical industry, and logging for timber. Industrial pollution of rivers and high levels of DDT/DDE and PCBs are further threats. Over-fishing has caused a decline of fish stocks in Russia and Japan which has led to an increasing tendency of birds on Hokkaido to move inland and scavenge on sika deer carcasses left by hunters, exposing them to a risk of lead poisoning through ingestion of lead shot
Stellers Sea Eagle status Vulnerable

Migration

Chief overwintering areas outside breeding range are in South Primorski region, Kuril Is and Sakhalin; many birds overwinter on Hokkaido, particularly on East coast. However, estimated that major part of Kachatkan sub-population does not leave peninsula, but merely moves to South parts of it. A young bird tracked by satellite remained in nest area in Kamchatka for nearly 2 months after fledging, up to mid-Oct; within 3 weeks it migrated 1360 km South through Kuril Is to Urup, Northeast of Hokkaido.

Distribution map

Stellers Sea Eagle distribution range map

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