Steller's fish eagle, Pacific sea eagle, White-shouldered eagle
Steller's sea eagle (Haliaeetus pelagicus) is a large diurnal bird of prey in the family Accipitridae. It was described first by Peter Simon Pallas in 1811. Typically, it is the heaviest eagle in the world.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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ScavengerScavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While sc...
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ArborealArboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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PredatorPredators are animals that kill and eat other organisms, their prey. Predators may actively search for or pursue prey or wait for it, often conceal...
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AltricialAltricial animals are those species whose newly hatched or born young are relatively immobile. They lack hair or down, are not able to obtain food ...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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Soaring birdsSoaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by m...
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MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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Generally solitaryGenerally solitary animals are those animals that spend their time separately but will gather at foraging areas or sleep in the same location or sh...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withMature Steller’s sea eagles have mostly dark brown to black plumage, with strongly contrasting white on the lesser and median upper-wing coverts, under-wing coverts, thighs, under-tail coverts, and tail. Their diamond-shaped, white tails are relatively long. The bold, pied coloration of adults may play some part in social hierarchies with other eagles of their own species during the non-breeding season, although this has not been extensively studied. A very rare dark morph, once regarded as a separate subspecies, H. p. niger, lacks white in its plumage, except for the tail. The eyes, bill, and feet of adults are yellow. The downy plumage of chicks is silky white on hatching, though it soon turns a smoky brown-grey. As in other sea eagles, remiges and rectrices of the first-year plumage are longer than those of adults. Juvenile plumage is largely a uniform dark soot-brown with occasional grey-brown streaking about the head and the neck, white feather bases, and light mottling on the rectrices. The tail of the immature eagle is white with black mottling distally. The young Steller's sea eagle has dark brown irises, whitish legs, and a blackish-brown beak. In all sea and fish eagles, the toes are relatively short and stout, with the bottom of the foot covered in spicules and the talons being relatively shorter and more strongly curved than in comparably sized eagles of forests and fields. The spicules, which are bumpy waves all along the bottom of their feet, allow them to hold fish that may otherwise slip out of their grasp.
Steller's sea eagles breed on the Kamchatka Peninsula, the coastal area around the Sea of Okhotsk, the lower reaches of the Amur River, and on northern Sakhalin and the Shantar Islands, Russia. The majority of birds winter south of their breeding range, in the southern Kuril Islands, Russia, and Hokkaidō, Japan. Some eagles, especially those that nest in the seacoast, may not migrate. Steller's sea eagles prefer habitats with large Erman's birches and floodplain forests of larches, alders, willows, and poplar. On Kamchatka, they overwinter in forests and river valleys near the coast but are irregularly distributed over the peninsula. Eagles that do migrate fly down to winter in rivers and wetlands in Japan, but will occasionally move to mountainous inland areas as opposed to the sea coast. Each winter, drifting ice on the Sea of Okhotsk drives thousands of eagles south. They may also occasionally fly over the northern ocean or perch on sea ice during the winter.
Steller's sea eagles are generally solitary and spend much of their time soaring or perched on sea cliffs or trees looking for prey. They hunt by day most commonly from a perch in a tree or rocky ledge located 5-30 m (16-98 ft) above the water; they may also hunt on the wing while circling 6-7 m (20-23 ft) above the water. Once located, the prey is captured by diving. Eagles sometimes hunt by standing in or near shallow water on a sandbank, spit, or ice-flow, grabbing passing fish. Relatively large numbers of these birds may gather in flocks on particularly productive spawning rivers in August through September due to an abundant food supply. Outside the breeding period, they often roost communally near their feeding sites. When salmon and trout are dying in winter after their summer spawning, feeding groups of Steller's sea eagles may mix with smaller Golden eagles and White-tailed eagles to exploit the food source. The timing, duration, and extent of Steller's sea eagles' migration usually depend on ice conditions and food availability. The birds depart between late March and late April, adults typically leaving before immatures. Migrants tend to follow sea coasts and usually fly singly. When in groups, migrants typically fly 100-200 m (330-660 ft) apart. Steller's sea eagles communicate with each other using a call similar to the White-tailed eagles but deeper and also make a deep barking cry, ra-ra-ra-raurau, in aggressive interactions. During the breeding season, they make calls that sound like very loud, deep-voiced gulls.
Steller's sea eagles are carnivores (piscivores) and scavengers; they mainly feed on fish favoring salmon and trout. These raptors also eat water birds, land birds, mammals, and occasionally carrion.
Steller's sea eagles are monogamous and form long-lasting pair bonds. Courtship usually occurs between February and March and consists of a soaring flight above the breeding area. These birds nest on large rocky outcroppings or at the tops of large trees on the coast and alongside large rivers with mature trees. A pair builds several aeries (nests) but only one nest is used for raising chicks. The nest itself is a bulky construction of twigs and sticks, at a height of up to 150 cm (59 in) and a diameter of up to 250 cm (98 in). The female lays her greenish-white eggs around April to May. Clutches can contain from 1 to 3 eggs, with 2 being the average. Usually, only one chick survives to adulthood, though in some cases as many as three will successfully fledge. After an incubation period of around 39-45 days, the chicks hatch. They are altricial and covered in whitish-down on hatching. The eaglets fledge in August or early September. Adult plumage is attained at 4 years of age, but first breeding does not typically occur for another year or two.
The main threats to these rare sea eagles include habitat alteration, industrial pollution, and overfishing, which in turn decrease their prey source. It was observed that recent heavy flooding, which may have been an effect of global climate change, caused almost complete nesting failure for the eagles nesting in Russian rivers due to completely hampering the ability of the parents to capture the fish essential to their nestlings' survival. Persecution of the bird in Russia continues, due to its habit of stealing furbearers from trappers. Due to a lack of other accessible prey in some areas, increasingly, eagles on Hokkaido have moved inland and scavenged on Sika deer carcasses left by hunters, exposing them to a risk of lead poisoning through ingestion of lead shot.
According to the IUCN Red List, the total population size of Steller's sea eagle is around 4,600-5,100 individuals, including around 1,830-1,900 breeding pairs. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List, and its numbers today are decreasing.
