Bird Research News

Vol.6 No.2

Steller’s Sea Eagle

2009.2.24.

Oh-washi (Jpn) Haliaeetus pelagicus

Morphology and classification
Classification: Accipitriformes Accipitridae
Total length:
Wing length:
Tail length:
Tarsus length:85-94cm♂ 560-590mm
330-400mm
96-115mm♀ 600-650mm
Culmen length: 62-75mm
Weight:4.9-9.0kg

The total length and weight after del Hoyo et al. (1994), and others after Kiyosu(1978).

Appearance:
Males and females are similar in plumage coloration. Adult birds are blackish
brown all over except for rectrices, wing
coverts, thighs and forehead, which areconspicuously white. The beak, feet andirises are bright yellow. Juveniles of theyear are dark brown all over with awhite patch on the wing. The tail has
blackish brown flecks on a whiteground. The beak is pale yellow, but Photo 1. Adult Steller's Sea
Eagle on the sea ice.
very dark at the tip and almost white atthe base. Young birds of 2-3 years of age have white tails with somedark mottles. The leading edges of the wings start to have whitefeathers. The beak is vivid yellow but some individuals may retaindark tips. Subadults of 4-5 years have white parts on the leadingedges of the wings and the tail, but some dark feathers may bemixed. Adult plumage will be completed at the age of 6 years(Nakagawa umpubl.).

Vocalization:
They bawl like "Kak, kak, kak, kak" in roosting forests and on thesea ice. Although similar, the call of Steller's Sea Eagles sounds
thicker and deeper compared to that of White-taile Eagles, whichsounds drier.

Distribution and Habitat
Distribution:
Steller's Sea Eagles are distributed in far
eastern Russia, Japan, northern China andthe Korean Peninsula. They breed in thelimited areas of far eastern Russia such as,
southern Koryak, the Kamchatka Peninsula, the lower reaches of the Amur River,the Shantar Islands, northern Sakhalin
Island, and the coastal areas of Magadan
and Khabarovsk. They over-winter primarily in northern Japan (Hokkaido andnorthern Honshu), the southern Kamchatka and the Kuril Islands, with some birds
in northeastern China, the Korean Peninsula and western Japan. The world population is estimated to be 5,000-7,000
birds, and approximately 2,000-2,500birds are assumed to winter in Japan andthe southern Kuril Islands.

Fig. 1. Distributions of
Steller's Sea Eagles.
Deep green: Breedinggrounds and the areas
as year-roundresidents. Light green:
Wintering grounds
and the areas as raremigrants.

Habitat:Steller's Sea Eagles build their nests on sea cliffs, huge rocks and in
the woods on a coastal slope, while they use seashores, lagoons andmouths of a salmon spawning river as a foraging site in the breeding
period. In inland areas, on the other hand, they build the nest in talltrees of a forest and cliffs along a river and around a lake and amarsh. Steller's Sea Eagles wintering in Hokkaido frequently feed insalmon spawning rivers and estuaries as well as forests, lakes andmarshes of a coastal area. They are also found in inland areas withdeer carcasses （Collar et al. 2001, Ueta & McGrady2000)．
24♪ http://www.bird-research.jp/1_shiryo/koe/oowashi_110119_yakumo_mju.mp3
Mutsuyuki Ueta

Life history
1

2

3

4

wintering
period56

78

breeding period

91011 12migration

Breeding system:
Steller's Sea Eagles are monogamous. The breeding period varies
with the region.

Nest and egg:
They build the nest in tall trees and on cliff ledges of the coastal
areas, such as the wetlands along rivers, around lakes and marshes.
They generally use birches and aspens as a nest tree in Kamchatka,
while they frequently nest in larches in the lower reaches of theAmur River and Sakhalin. Their breeding season starts in late
February in Kamchatka with a regional variation. They exhibit
display flight while calling at the same time, and start building anest which is completed in early April. The egg-laying generally
starts in late April, but may occur as late as late May. The clutch
size is usually 2 eggs, with a range of 1-3 eggs. The color of theegg is white.

Incubation and nestling periods:
The incubation period is 1-1.5 months. The eggs hatch from midMay to mid-July. The hatchlings are covered with gray down, andare fed fish and birds by the parent birds. Fish (pikes, etc.) andbirds account for 80% and 10% of the food carried to the nest,
respectively in the lower reaches of the Amur River. In Kamchatka
and Sakhalin, on the other hand, Japanese pond smelts(Hypomesus nipponensis) and cod are fed to the nestlings. Thejuveniles grow up to the size of half to 2/3 of the parents by theend of July. They usually fledge in August, but occasionally inearly September (Lobkov & Neifel'dt 1986).

Migration and wintering ground:
Steller's Sea Eagles set out on a migration from the breeding
grounds in September. Those breeding in Kamchatka, for instance,head for the southern part of the peninsula and the Kuril Islands towinter. The majority of the Steller's Sea Eagles that breed in thenorthern part of the Sea of Okhotsk such as Magadan, the lower
reaches of the Amur River and northern Sakhalin Island go south
through Sakhalin and arrive in Hokkaido via the Soya Strait afterOctober. After they land in Hokkaido, they generally travel southeast to the Shiretoko Peninsula along the coast of the Sea ofOkhotsk. Some of them stay for a short period of time in salmon
spawning rivers from the Soya Cape (the northernmost cape ofJapan) to the Shiretoko Peninsula. The recent studies of winteringeagles, however, have revealed that most of them go over to Kunashirito and Etorofuto Islands of the Krill Islands to spend the firstpart of the winter. A total of nearly 2,000 Steller's Sea Eagles headeast along the coast of the Shiretoko Peninsula between late October and late November. More than 400 birds pass the coast in asingle day at the peak period. The eagle count showed that 1,135
Steller's Sea Eagles wintered in Kunashirito and Etorofuto Islands
at the end of December 1998. They are assumed to return to eastern Hokkaido again in January because wintering Steller's Sea
Eagles increase in number in the coastal areas of the Shiretoko
Peninsula and Lake Furen in January. In addition to eastern Hokkaido, Steller's Sea Eagles winter in the Ishikari River basin, riversof the Hidaka and Oshima regions in central-south Hokkaido, andIwate and Miyagi Prefectures (north-east Honshu). Therefore, thetotal of Steller's Sea Eagles wintering in northern Japan amounts to1,700-2,300 birds. Some of them begin to depart their winteringsites for the breeding ground as early as March. In spring, they
retrace the route along the coast of the Sea of Okhotsk to Sakhalin,
stopping over at lakes and marshes. In April many Steller's Sea
Eagles are observed to fly north out of Cape Soya. (McGrady et al.
2000, WGWS 1996, Ueta et. al. 2004).

Bird Research News

Vol.6 No.2

2009.2.24.

© Japan Bird Research Association
Sumiyoshi 1-29-9, Fuchu, Tokyo, Japan

Diet and foraging behavior
The diet of Steller's Sea Eagles consists of fish, birds and mammals
including their carcasses. The fish is composed principally of Salmonid fish such as pink and chum salmons and gadidae fish such as
Alaska pollacks (Theragra chalcogramma), the prey bird is comprised primarily of alcids, gulls and cormorants, and the mammal ismainly made up of foxes, muskrats, hares and ringed seals. In thebreeding season, fish predominate their diet in the lower reaches of
the Amur River and Kamchatka, while birds occupy the major part of
it in the northern coast of the Sea of Okhotsk (Utekhina et al. 2000).
From late autumn to early winter in Hokkaido, they gather in estuaries or along rivers to forage for pink and chum salmons. In the coastof the Shiretoko Peninsula, they consume carcasses of whales and pinnipeds washed up on the beach by roughseas. During the coldest period ofwinter, they ingest frozen salmon
carcasses preserved in the river. Whenthey finish off the supply of thesecarcasses, however, they turn to leftover fish from fishery. A large numberof Steller's Sea Eagles are attracted tosmall fish, such as White-edged rock- Photo 2. Steller's Sea Eagles
gathered at an ice-fishing
fish, tidepool gunnel and Japanesesite (above) and around adace discarded from ice fishing on
whale carcass (below).
lakes of eastern Hokkaido.

Topics of ecology, behavior and conservation● Changes of food and distribution
個体数

The studies of the Work- 2500
羅臼
Rausu, eastern Shiretoko
斜里
Shari, western Shiretoko
ing Group for White2000
知床以外
Other areas
tailed Eagles and Steller's
Sea Eagles show a long- 1500
term change in the distri1000
bution of Steller's Sea
Eagles wintering in Hok- 500
kaido. More than 90% of0
the Steller's Sea Eagles
85 86 87 89 90 93 94 95 96 97 98 99 00 02 03 04 06 07 08
wintering in Hokkaido Fig. 2. Long-term changes in the abunconcentrated in the coast
dance and distribution of winteringof Rausu at the eastern
Steller's Sea Eagles.(Based on the study
base of the Shiretokoof the Working Group for White-tailed
Eagles and Steller's Sea Eagles).
Peninsula from the mid1980s to 1990. They wereattracted to fish discarded from the gill net fishing of Alaska pollacks
along the coast of Rausu. In the 1990s, however, the Alaska pollack
haul declined rapidly to 10% of that of the peak period. With thedrop of the haul, Steller's Sea Eagles gathering in the coast of Rausu
decreased in number as well. They dispersed to other areas of Hokkaido (Fig. 2). They increased in lakes where the ice fishing wascarried out, such as Lakes Furen and Akkeshi and rivers with salmon
carcasses. In addition, they started to be observed in the inland areasof eastern Hokkaido where few Steller's Sea Eagles had wintered
before. In these sites, they were attracted to the carcasses of shika
deer which rapidly increased in the 1990s. Some of the deer carcasses were left over from hunting, which was responsible for lead poisoning of some eagles. In the coast of Rausu, tour boats operated in
the sea ice period started to place fish scrap, which attracted many
White-tailed and Steller's Sea Eagles (Nakagawa 1999, 2007).

● Conservation issues
Lead poisoning has represented a serious threat to Steller's Sea Eagles since the mid-1990s. They suffer from lead poisoning by accidentally ingesting lead fragments when they consume deer carcasses
or remnants hunters killed with lead bullets. In the the winter of 1998

バードリサーチ生態図鑑
when cases of lead poisoning occurred most frequently, a total of 26
White-tailed and Steller's Sea Eagles died of lead poisoning. In Hokkaido, the use of lead bullets for deer hunting was banned by 2001,
and the cases of lead poisoning in eagles have decreased accordingly.
However, up to 5-8 White-tailed and Steller's Sea Eagles are stillfound dead due to lead poisoning every year. A regional ban on thelead bullet use in Hokkaido is not sufficient, and the nationwide
restriction of the possession and sale of lead bullets is urgently required to prevent eagles from falling victim to lead poisoning. Inaddition, wintering Steller's Sea Eagles are not only killed by collision with automobiles and trains but also electrocuted on powerlines. In Sakhalin, on the other hand, the breeding habitat of Steller's
Sea Eagles has been degraded due to the development of energy
resources. In 2006, a large amount of seabird carcasses covered withoil were washed up on the coast of the Shiretoko Peninsula, and two
Steller's Sea Eagles died of secondary oil poisoning because they
consumed the polluted seabirds. It is also confirmed that they haveaccumulated chlorinated hydrocarbons, such as PCB in their body
(Lead Poisoning Network 2004, etc.).

Literature
Collar N.J., et al. (eds.) 2001. Threatened Birds of Asia: The BirdLife International
Red Data Book Part A. BirdLife International, Cambridge.
del Hoyo J., Elliot A. & Sargatal J. (eds.) 1994. Handbook of the Birds of theWorld. Vol.2. New World Vultures to Guineafowl. Lynx Editions, Barcelona.
Kiyosu Y. 1978. Great Reference of Japanese Birds II Revised edition with supplement. Kodansha, Tokyo. [J]Lobkov E.G. & Neifel'dt I.A. 1986. Distribution and biology of the Steller's Sea
Eagle Hariaeetus pelagicus (Pallas). Proceedings of the Zoological Institute 150“The Distribution and Biology of Birds of Altai and Far East”, 107-146. (YuzoFujimaki translation. "Birds of the Far East -11" pp.1-32 . the Far Eastern Bird
Society, Obihiro) [J (original in Russian)]
McGrady M.J. et al. 2000. Migration and wintering of Juvenile and immature
Steller's Sea Eagle. In Ueta M. & MacGrady M.J. (eds.). First Symposium on
Steller's and White-tailed Sea Eagles in East Asia. pp.83-90. Wild Bird Societyof Japan, Tokyo.
Nakagawa H. 1999. The Steller's Sea Eagle. In Shiretoko museum（eds.). Birds inShiretoko. pp.178-219 . Hokkaido Shimbunsha, Sapporo. [J]Nakagawa H. 2007. The Steller's Sea Eagle and the White-tailed Eagle: conservation measures. Kakkou (Sapporo Chapter of Wild-Bird Society of Japan newsletter) 290:6-9. [J]
WGWS: Working Group for White-tailed Eagles and Steller's Sea Eagles. (1996)
Yearly fluctuations of number of Steller's Sea Eagle and White-tailed Eagles
wintering in Hokkaido and northern Honshu. The status of rare species of wild
fauna and flora report consigned by the Environment Agency in 1995 fiscalyear. Pp1-9 . Wild-Bird Society of Japan, Tokyo. [J]Ueta M., Fukuda Y., Matsumoto K. & Nakagawa H. 2004. The migration of Steller's Sea Eagles in the Shiretoko Peninsula. Strix 22:71-80. [J+E]
Ueta M. & MacGrady M.J. (eds.) 2000. First Symposium on Steller's and Whitetailed Sea Eagles in East Asia. 127pp. Wild Bird Society of Japan, Tokyo.
Ueta M., Sato F., Nakagawa H. & Mita N. 2000. Migration routes and differencesof migration schedule between adult and young Steller's Sea Eagles Haliaeetus
pelagicus. Ibis 142:35-39.
Utekhina I., Potapov E. & MacGrady M.J. 2000. Diet of the Steller's Sea Eagle inthe Northern Sea of Okhotia. In Ueta M. & MacGrady M.J. (eds.). First Symposium on Steller's and White-tailed Sea Eagles in East Asia. pp.83-90. Wild Bird
Society of Japan, Tokyo.
Lead Poisoning Network of Eagles. 2004. Aiming at stopping the lead poisoning ineagles VI. Lead Poisoning Network of Eagles, Kushiro. [J]AuthorHajime NAKAGAWA Shiretoko Museum, Shari TownAs soon as I graduated the Agriculture Department of
Hokkaido University in 1973, I moved to eastern Hokkaido
to live and work on nature conservation activities as wellas bird studies. I became a curator of the Shiretoko Museum in 1978 and was engaged in educational activities aswell as studies of bird and mammal ecology. As the secretary-general of the Shiretoko Foundation, I began to work
to promote the use of the Shiretoko National Park and help
with the management in 1991. I have served as the directorof the Shiretoko Museum since 1995. I specialize in animal
ecology and wildlife conservation and management.

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