Steller's Sea Eagle

About the Steller's sea eagle

Steller's sea eagle, also known as the Pacific sea eagle or white-shouldered eagle, is a very large bird of prey in the family Accipitridae, first described by Peter Simon Pallas in 1811. It's named for the German naturalist Georg Wilhelm Steller, and the International Ornithologists' Union has designated "Steller's sea eagle" as its official name, though it's also known as Steller's fish eagle, and in Russian as the "white-shouldered sea eagle." A 1996 genetic analysis found that it diverged from the lineage that produced the bald eagle and the white-tailed eagle around three to four million years ago; all three species share yellow eyes, beaks, and talons, a trait their next-closest relative, Pallas's fish eagle, lacks.

A very rare dark morph, once thought to be a separate subspecies called H. p. niger, lacks the white plumage of typical birds except on the tail. Long believed extinct after last being seen in 1968, a female matching this dark form hatched in captivity in Germany in 2001 and was later moved to Tierpark Berlin; one of her offspring, a male hatched in 2014, now lives at Skandinavisk Dyrepark in Denmark. Both of the dark female's parents had ordinary coloring, which suggests the dark morph is simply a rare variation rather than a genuine subspecies.

Steller's sea eagle is the largest species in the genus Haliaeetus and one of the largest raptors alive. It's typically the heaviest eagle in the world, though the harpy eagle and Philippine eagle can exceed it on some other measurements. Its wingspan, at a median of roughly 2.13 to 2.2 m (7 ft), is among the largest of any living eagle, and some unverified records claim wingspans up to 2.8 m (9 ft 2 in). Its bill is probably the largest of any living eagle as well, similar in robustness (if slightly shorter) to those of the largest Old World vultures. Mature birds have dark brown to black plumage set off by strongly contrasting white on the shoulders, wing coverts, thighs, and tail, with a yellow beak, unlike other sea eagles, that stays yellow even in juveniles. The species also has 14 tail feathers rather than the 12 found in most other sea eagles.

Behavior and diet

Steller's sea eagle feeds mainly on fish, hunting in shallow water like other members of its genus, and is considered an apex predator within its environment. In river habitats its preferred prey is Pacific salmon and trout, particularly pink salmon and chum salmon, supplemented at times by grayling and three-spined stickleback; the eagles regularly take fish weighing 6 to 7 kg (13 to 15 lb), well above the average adult mass of the salmon species they favor. Along the coast, nesting eagles also take fish such as Bering wolffish and smooth lumpfish. Water birds round out the diet. Though normally solitary, the species will gather in large numbers where food is abundant — on Kamchatka, aggregations of up to 700 eagles have been recorded at productive spawning rivers between August and September.

Vocally, the species produces a deep barking cry rendered as "ra-ra-ra-raurau," along with honking calls similar to those of Canada geese; during aggressive encounters its calls resemble the white-tailed eagle's but pitched lower, and during breeding-season display the birds make loud, deep calls likened to large gulls.

Range and habitat

Steller's sea eagle breeds on Russia's Kamchatka Peninsula, along the coast of the Sea of Okhotsk, on the lower Amur River, and on northern Sakhalin and the Shantar Islands. Many birds migrate in winter to Korea, Japan, and China, with most wintering south of the breeding range in the southern Kuril Islands and on Hokkaido, Japan; drifting sea ice on the Sea of Okhotsk each winter pushes thousands of eagles south, with numbers peaking in Japan's Nemuro Strait in late February before birds head back north between late March and late April. Some coastal-nesting eagles don't migrate at all. Nests are built on large rocky outcroppings or in the tops of large coastal or riverside trees, with a preference for Erman's birch and floodplain forests of larches, alders, willows, and poplars.

The species is a rare vagrant to North America, but one individual — nicknamed "Stella" — has drawn sustained attention after first being spotted near Alaska's Denali National Park in August 2020. It went on to appear in Texas, New Brunswick, Quebec, Nova Scotia, Massachusetts, and Maine before settling into a pattern of returning to Newfoundland, where it has stayed year-round in recent years. In spring 2024 it began showing nesting behavior there and has been aggressive toward nearby bald eagles.

Conservation status

Steller's sea eagle is listed as Vulnerable on the IUCN Red List. The Kamchatka Peninsula in far eastern Russia holds a relatively large share of the world's population, with an estimated 4,000 eagles living there. No specific threats to the species are detailed beyond this population picture.