Steller's sea eagle is among the heaviest eagles on Earth and one of the most habitat-restricted raptors in the world, with a global range concentrated along the cold coasts and salmon rivers of the Russian Far East and the wintering grounds of northern Japan [BirdLife International 2021]. Its survival is tightly bound to the seasonal pulse of Pacific salmon and to a handful of intact coastal nesting areas, leaving the species unusually exposed to changes in just a few landscapes. This profile examines the eagle's biology, its narrow geographic range, and the conservation work underway to keep its small, declining population stable.
Biology and Identification
Steller's sea eagle is a massive, sexually dimorphic raptor in the family Accipitridae. Females are substantially larger than males, weighing roughly 6.2–9.5 kg compared with about 4.9–6.8 kg in males, which makes it on average the heaviest eagle in the world even though its wingspan and total length are exceeded by some other large raptors [BirdLife International 2021]. Adults are unmistakable: a deep brownish-black body offset by white shoulders, white thighs, a white wedge-shaped tail, and an exceptionally large, deep, orange-yellow bill that is the largest of any eagle.
The species is strongly tied to water and to fish. Pacific salmon and trout dominate the diet across much of the range, supplemented by other fish, waterbirds, and carrion; on the Japanese wintering grounds, Pacific cod and Alaska pollock (Gadus chalcogrammus) become important prey [BirdLife International 2021]. The eagle's seasonal use of habitat tracks this food supply closely. Satellite-tracking studies have shown that in autumn the birds concentrate along rivers, a pattern linked to the abundance of post-spawning salmon carcasses, while in winter they spread across seacoasts, lakesides, and remaining open rivers [Ueta et al. 2003].
Steller's sea eagles are long-lived and slow to reproduce. Pairs are monogamous and territorial, building bulky stick nests on coastal cliffs or in large trees, and maintaining several alternate nests within a territory. Clutch size is typically one to three eggs, with breeding success limited by the availability of large nest trees and undisturbed coastal sites — a dependence that makes the species sensitive to logging and coastal development [BirdLife International 2021].
Habitat and Range
Steller's sea eagle has one of the most geographically restricted ranges of any large raptor. Its breeding distribution is essentially confined to the Russian Far East, along the coasts of the Sea of Okhotsk, the Kamchatka Peninsula, the lower Amur River, northern Sakhalin, and the Shantar Islands, with nesting concentrated in coastal forests and river valleys that combine tall nest trees with productive fishing waters [BirdLife International 2021; Birds Russia 2024].
Outside the breeding season the population shifts south. Many birds winter in the southern Kuril Islands and on Hokkaidō, Japan, where wintering eagles concentrate around the Nemuro Strait and the drift-ice edge of the Sea of Okhotsk; smaller numbers reach the Korean Peninsula and coastal China [BirdLife International 2021]. Satellite tracking of juvenile and immature eagles documented long autumn and winter migrations from natal areas in Magadan, Khabarovsk, the Amur region, Sakhalin, and Kamchatka, with dispersal and migration spanning September through January along consistent coastal routes [McGrady et al. 2003]. This reliance on a narrow set of breeding coasts and an even smaller set of wintering areas means that pressures concentrated in a few places can affect a large share of the global population.
In accordance with NRWL sensitive-species policy, specific site locations, corridor routes, and seasonal movement details are not disclosed in this article.
Conservation Status
Steller's sea eagle is listed as Vulnerable on the IUCN Red List, assessed by BirdLife International in 2021 under criterion C2a(ii), reflecting a small global population that is in continuing decline and concentrated in a single subpopulation [BirdLife International 2021]. The global population is estimated at roughly 4,600–5,100 individuals, including approximately 1,830–1,900 breeding pairs, and the overall trend is decreasing [BirdLife International 2021].
The species is listed on CITES Appendix II, which regulates international trade to prevent it from becoming incompatible with the species' survival [CITES 2023]. It is also included in the Convention on the Conservation of Migratory Species of Wild Animals (CMS), and is covered by bilateral migratory-bird protection agreements between Russia and Japan, the Republic of Korea, and other range states [CMS 2024]. Within range countries it receives national legal protection, including designation as a Natural Monument in Japan [BirdLife International 2021].
Threats
Habitat alteration and coastal development are central pressures on the breeding range. Logging removes the large, old trees the eagles depend on for nesting, while oil and gas development on the Sakhalin shelf and along the Sea of Okhotsk coast overlaps directly with key nesting areas, raising the risk of disturbance, habitat degradation, and pollution in the species' core breeding habitat [BirdLife International 2021].
Lead poisoning is a well-documented and persistent threat on the Japanese wintering grounds. Eagles scavenging the carcasses and gut piles of Sika deer ingest fragments of lead rifle bullets and shotgun slugs left by hunters; by 2007, well over a hundred Steller's and white-tailed eagles in Hokkaidō had been diagnosed as lead-poisoning fatalities [Saito 2009]. Despite Hokkaidō's regulations requiring non-lead ammunition for deer hunting, monitoring of raptors in Japan from 2015 to 2018 found that lead exposure was still occurring, indicating that the threat has not been eliminated [Ishii et al. 2020].
Reduced prey availability and ecological traps also affect the population. Overfishing and disruption of salmon spawning runs reduce the food base, and in parts of the northern Sea of Okhotsk eagles that linger at productive, late-freezing rivers can become cut off from wintering grounds as surrounding waters ice over [BirdLife International 2021]. Additional hazards include pesticide and industrial contamination, collisions, and localized persecution.
What Is Being Done
Long-term population monitoring. Russian researchers, including teams associated with Birds Russia, conduct sustained monitoring of breeding populations across Sakhalin, the lower Amur, and the northern Sea of Okhotsk, tracking reproduction and survival to inform conservation planning [Birds Russia 2024]. In connection with oil and gas development on Sakhalin, an eagle monitoring programme has been maintained since 2004 to track the species in areas affected by industrial activity [BirdLife International 2021].
Reducing lead exposure. Conservation and veterinary organizations in Japan, working alongside Hokkaidō authorities and the Ministry of the Environment, have promoted non-toxic ammunition, treated poisoned birds, and documented ongoing exposure to support stronger enforcement of lead-ammunition restrictions [Saito 2009; Ishii et al. 2020].
International coordination. Listing under CITES Appendix II and CMS, together with bilateral migratory-bird agreements among Russia, Japan, and neighbouring states, provides a framework for coordinated protection across the species' breeding and wintering ranges [CITES 2023; CMS 2024]. National protections in range states, including Natural Monument status in Japan, reinforce these measures [BirdLife International 2021].
Research on movements and habitat needs. Satellite-tracking and habitat-use studies have clarified the eagle's seasonal dependence on salmon rivers, coastal feeding areas, and migration corridors, providing the evidence base needed to prioritize site protection [Ueta et al. 2003; McGrady et al. 2003].
How Readers Can Help
Support non-lead ammunition. Where you hunt or know hunters, encourage the use of copper and other non-lead bullets and slugs. Lead poisoning from scavenged carcasses remains a leading documented cause of death for wintering Steller's sea eagles, and reducing spent lead in the environment directly benefits the species [Saito 2009; Ishii et al. 2020].
Be a responsible wildlife viewer. Steller's sea eagles draw birdwatchers to Hokkaidō and other wintering sites. Choose operators that keep a respectful distance from roosting and feeding eagles, and avoid disturbing birds at nesting and wintering concentrations.
Contribute to citizen science. Log eagle observations through platforms such as eBird and iNaturalist. Verified records, especially of vagrant individuals far outside the normal range, help researchers and contribute to range-mapping and status assessments.
Stay informed and share accurate information. Support organizations conducting monitoring and lead-poisoning prevention in Russia and Japan, and share science-based information about the species' narrow range and its dependence on intact salmon rivers and coastal nesting habitat.
References
[BirdLife International 2021] BirdLife International. (2021). Haliaeetus pelagicus. The IUCN Red List of Threatened Species 2021: e.T22695147A204871862. https://doi.org/10.2305/IUCN.UK.2021-3.RLTS.T22695147A204871862.en
[Birds Russia 2024] Russian Bird Conservation Union (Birds Russia). (2024). Steller's Sea Eagle: ecology, evolution and conservation (project overview). https://birdsrussia.org/projects/steller-s-sea-eagle-ecology-evolution-and-conservation/
[CITES 2023] CITES. (2023). Appendices I, II and III. Convention on International Trade in Endangered Species of Wild Fauna and Flora. https://cites.org/eng/app/appendices.php
[CMS 2024] Convention on the Conservation of Migratory Species of Wild Animals. (2024). Haliaeetus pelagicus species page. https://www.cms.int/species/haliaeetus-pelagicus
[Ishii et al. 2020] Ishii, C., Ikenaka, Y., Nakayama, S.M.M., Kuritani, T., Nakagawa, M., Saito, K., Watanabe, Y., Ogasawara, K., Onuma, M., Haga, A. & Ishizuka, M. (2020). Current situation regarding lead exposure in birds in Japan (2015–2018); lead exposure is still occurring. Journal of Veterinary Medical Science, 82(8), 1118–1123. https://doi.org/10.1292/jvms.20-0104
[McGrady et al. 2003] McGrady, M.J., Ueta, M., Potapov, E.R., Utekhina, I., Masterov, V., Ladyguine, A., Zykov, V., Cibor, J., Fuller, M. & Seegar, W.S. (2003). Movements by juvenile and immature Steller's Sea Eagles Haliaeetus pelagicus tracked by satellite. Ibis, 145(2), 318–328. https://doi.org/10.1046/j.1474-919X.2003.00153.x
[Saito 2009] Saito, K. (2009). Lead poisoning of Steller's Sea-Eagle (Haliaeetus pelagicus) and White-tailed Eagle (Haliaeetus albicilla) caused by the ingestion of lead bullets and slugs, in Hokkaido, Japan. In R.T. Watson, M. Fuller, M. Pokras & W.G. Hunt (eds.), Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. https://doi.org/10.4080/ilsa.2009.0304
[Ueta et al. 2003] Ueta, M., McGrady, M.J., Nakagawa, H., Sato, F. & Masterov, V.B. (2003). Seasonal change in habitat use in Steller's sea eagles. Oryx, 37(1), 110–114. https://doi.org/10.1017/S003060530300019X