The Steller’s sea eagle, belonging to genus Haliaeetus, is a diurnal bird of prey. It was first described by naturalist Peter Simon Pallas as Aquila pelagic in 1811. This species was moved to genus Haliaeetus by George Robert Gray in 1849. The common name of this bird is given after Georg Wilhelm Steller, a German naturalist.
Species: H. pelagicus
The scientific name for Steller’s sea eagle is Haliaeetus pelagicus.
Sexual dimorphism is not seen, but females are larger than males. Adults range between 85 to 95 centimeters in length. Females weigh around 9 kilograms, while males tend to be around 6 kilograms.
The wingspan of the female stands at 132 to 136 centimeters, and the males’ wingspan is approximately 117 to 120 centimeters. Their plumage is black to dark brown on most parts of the body. Their crown, thighs, tails, and shoulders are white in color. They have large, yellow beaks. They possess sharp talons that are also yellow in color.
This species mostly inhabit estuaries and coastal cliffs. They breed along lakeshore forests, rivers or sea coasts with mature trees nearby.
At times, they can be seen perching on northern sea waters.
The Steller’s sea eagle breeds in Russia – on the Kamchatka Peninsula and throughout the Sea of Okhotsk. During winter most of its population move along rivers in Japan, and some of its population move inland mountainous areas instead of staying at coastal areas.
In fact, a small population remains in the Kamchatka Peninsula in Russia. The scattered population is also seen in North Korea, South Korea, and China.
This bird species is mostly solitary; commonly seen sitting on large tree branches. They congregate only during breeding season. However, at times, they can be seen in large numbers in places with the abundant food supply, such as nearby a river abundant in salmon and other fishes. They stay active during the daytime, and they migrate to warmer regions during winter. The size of each individual’s home range is not known. They locate their prey from perch, or while in flight, and then they swoop down to catch it from the water surface. They also stand in shallow water-bodies to catch fish. If fish is not always abundant, they feed on sea lion or seal carcasses. In large congregations at feeding sites, individuals steal food from others mouth; and this behavior is popularly called ‘Kleptoparasitism.’
Mating season starts around February or March. They make their breeding nest on rocky outcrops, or on large trees, and it can be as high as 148 ft from the ground. Nests, with the maximum diameter of up to 250 centimeters, are made (and lined) with sticks and twigs. Nest building follows copulation.
Females lay 1 to 3 eggs in April or May. The eggs, which are a bit larger compared to those of a Harpy eagle, are greenish-white in color, and it weighs around 155 to 165 grams. The incubation period lasts from 39 to 46 days. The newly hatched ones are altricial, and they are cover with whitish down. Generally, one chick successfully fledges – somewhere in August or September. They get their adult plumage at the age of four.
Their primary food is salmon – taken either alive or dead. When salmon is not abundant or scarce, they also feed on other food resources, such as small mammals, carrions, gulls, crabs, or mussels.
Their lifespan in the wild is not known. But researchers believe that it could be similar to that of its close relatives, namely White-tailed sea eagles that live for around 20 – 25 years.
These species make a “Ra-ra-ra-raurau”, which is a deep barking-like sound associated with aggressive interactions. They also emit deep, loud sounds during the breeding season.
Adult specimens have no predators. However, eggs and chicks are vulnerable to birds, or small arboreal mammals, such as ermine, martens or sables.
Industrial pollution, overfishing causing a food shortage, and ecosystem changes are big threats to their survival. Their current population is believed to be around 5000 and their number is sharply decreasing.
The IUCN Red List of Threatened Species has kept this species in the ‘Vulnerable’ category.
This species is legally protected in Japan, Russia, South Korea, and China. Key wild habitats are recognized as nature reserves in Japan and Russia.
This is a monotypic species, even though a doubtful subspecies H. p. Niger has been named. This name was given to the population that had no white feather apart from its tail, and it was believed to be a year-long resident of Korea. H. p. Niger was last seen in 1968, and it is believed to be extinct. It is also argued that H. p. Niger is a rare morph, and it is not a valid subspecies.
Steller’s sea eagle enjoys the protection of the Convention on International Trade of Endangered Species, where it is listed under Appendix II.
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