First Symposium on Steller’s and White-tailed Sea Eagles in East Asia pp. 107-109, 2000
UETA, M. & MCGRADY, M.J. (eds) ©Wild Bird Society of Japan, Tokyo Japan

Lead poisoning in Steller’s Sea Eagles and White-tailed Sea Eagles
Nobumichi KUROSAWA
Hokkaido Veterinary Medical Association, 3-10-11 Sakuraoka, Tesikaga-cho,
Hokkaido 088-3213 Japan. e-mail: kuromail@d2.dion.ne.jp

Lead poisoning in waterfowl has been known in Europe and the United States for a longtime (Anderson 1975, Guitart et al. 1994). And is caused by the consumption of lead left in theenvironment as the result of hunting activities. In Japan, the problem became widely known in1989 when many Whooper Swans Cygnus cygnus suffered from lead poisoning in Miyajima
Numa (Jin et al. 1989). Apart from this direct poisoning of waterfowl from ingesting leadpellets, secondary poisoning occurs. In North America more than 300 Bald Eagles Haliaeetus
leucocephalus died when they fed upon waterfowl that had been shot or had ingested leadpellets (Elliott et al. 1992, Locke et al. 1992). Similar cases of lead poisoning caused byingesting contaminated waterfowl have been found in Japan in Steller’s Sea Eagles H.
pelagicus in 1988 (R. Shimura unpublished) and 1996 (K. Saito unpublished).
Recently, researchers have found a new source of lead poisoning in eagles in Hokkaido,
Japan, when lead bullet fragments in the remains of deer are consumed by scavenging eagles.
According to records kept by the Kushiro Zoo, seven Steller’s Sea Eagles and one
White-tailed Sea Eagle H. albicilla were brought to the zoo, dead or emaciated in winter
1994-95. Records show that most of these eagles were found in inland areas, away from their’typical’ habitat on the coast and along the lower reaches of big rivers. There had been noprecedent for this level of mortality, and at that point in time lead poisoning was not known to
be a major cause of sea eagle mortality. In winter 1995-96, five Steller’s Sea Eagles and one
White-tailed Sea Eagle were brought to the zoo (Kushiro Zoo 1996). In the search for thecauses of these mortalities, the blood of one bird was examined, and it was found to besuffering from lead poisoning (R. Shimura unpublished).
In 1997, K. Saito (DVM) and Y. Masuda (DVM) independently examined the cause ofdeath of six eagles that died in the winter of 1996-97. Both veterinarians found that eagles diedfrom eating lead fragments from rifle bullets in the carcasses of Sika Deer Cervus nippon.
They advised the Environment Agency of Japan to take immediate steps toward resolving thisproblem. In total, five Steller’s and three White-tailed Sea Eagles were found to have died oflead poisoning in that winter.
The number of eagle victims increased during the winter of 1997-98, when 19 birds (16Steller’s Sea Eagles and three White-tailed Sea Eagles) were found from December to May.

10830
Steller's Sea Eagle

25White-tailed Sea Eagle

20151050
1995-1996

1996-1997

1997-1998

1998-1999

Fig. 1. The number of Steller's and White-tailed Sea Eagles that died of lead poisoning each winter inHokkaido.

Two more Steller’s Sea Eagles were found afterward and as of July 1999 the total known
mortality of eagles during that winter is 21. Furthermore, 16 Steller’s Sea Eagles and nine
White-tailed Sea Eagles were found to have died of lead poisoning in winter 1998-99 (Fig. 1).
Historically, most sea eagles that wintered in Japan gathered on the coast of the Shiretoko
peninsula, attracted by an abundance of Walleye Pollack Theragra chalcogramma discarded byfishermen this situation persisted until 1990 (WGWS 1996). Because of the recent decline in
the fishery, many eagles moved to inland areas in search of more plentiful food (WGWS1996). Concurrently, the number of Sika Deer has greatly increased and the Hokkaido
Government has encouraged people to hunt more deer in order to lessen agricultural damage.
This increase in hunting has resulted in more deer carrion being available to eagles. Because awhole deer carcass is heavy, many deer hunters leave some portion of the carcass in the field
and take away only the choice parts. Also, some injured deer die in the field, unfound byhunters. Because almost all deer are shot using lead bullets, and these bullets usually fragmentin the deer body (Hokkaido Government unpublished), eagles are exposed to the threat of leadpoisoning.
Of 30 eagle carcasses retrieved last winter (1997-98), 21 were identified as being leadpoisoned. If this rate of mortality (70%) is an accurate measure of lead poisoning’s overall
contribution to mortality, then it has caused more than 3-fold increase in known yearly eagle
mortality in Hokkaido. The increase of mortality due to starvation seems to affect younger
eagles more, presumably because they are less efficient hunters/scavengers. However,mortality caused by lead poisoning affects all age classes equally. As the death of adult
raptors usually has a larger influence on the population, a high rate of mortality in eagles due tolead poisoning might cause declines in their population (Ueta & Masterov 2000).
The Lead Poisoning Network started a study of the distribution and behavior of eagles in109
Eastern Hokkaido in winter of 1998-99. The Network found that at least 214 eagles are
dependent upon deer carcasses in inland areas through the winter, and that another 400 eagles
have access to deer carcasses in inland areas, although they were found in coastal areas(LPNE 1999). The Wild Bird Society of Japan also reported that some eagles moved toinland area from coastal area in spring to eat deer carcasses (Ueta 1998).
Reports of lead poisoning are occurring more regularly, and effective measures to control
this source of additional eagle mortality should be taken immediately. It is important that thecomplete carcasses of deer shot by hunters should be removed. It is likely that the mosteffective measure in controlling lead contamination of carcasses would be to use lead-free orcopper bullets. At present only about 3% of deer hunters use copper ammunition. If thissituation continues, then one has to worry about the fate of eagles wintering in Japan. The
Environment Agency of Japan is planning a ban on the use of lead bullets for deer hunting by
2001 at the latest.

LITERATURE CITED
Anderson W.L. 1975. Lead poisoning of waterfowl at Rice Lake, Illinois. J. Wildl. Manage. 39: 264-270.
Elliott, J.E., Langelier, K.M., Scheuhammer, A.M., Sinclair, P.H. & Whitehead, P.E. 1992. Incidence of leadpoisoning in Bald Eagles and lead shot in waterfowl gizzards from British Columbia 1988-91. Canadian
Wildlife Service Program Note No.200, Canadian Wildlife Service, Quebec, Canada.
Guitart R., To-Figueras, J., Mateo R., Bertolero, A., Cerradelo, S. & Martinez-Vilata, A. 1994. Lead poisoning
in waterfowl from the Ebro Delta, Spain: Calculation of lead exposure thresholds for Mallards. Arch.
Environ. Contam. Toxicol. 27: 289-293.
Jin, K., Ohyama, T., Katoh,Y., Chiba, Y. & Tsuzuki, T. 1989. Lead poisoning in Whooper Swans at Miyajima
swamp in Hokkaido. Bull. Hokkaido Inst. Pub. Health 39: 107-109.
Kushiro Zoo. 1996. Newsletter of the Zoo ’Fureai’ No.56. Kushiro Zoo, Kushiro, Japan.
Lead Poisoning Network of Eagles (LPNE). 1999. Annual Report of 1998. LPNE, Kushiro, Hokkaido,Japan. In Japanese.
Locke, L.N. & Friend, M. 1992. Lead poisoning of avian species other than waterfowl. In: Pain, D.J. (ed).
Proceeding of an International Waterfowl and Wetlands Research Bureau Workshop Spec. Publ. 16. pp.
19-22. International Waterfowl and Wetlands Research Bureau, Slimbridge, UK.
Ueta, M. 1998. Problem of Lead poisoning in birds. Yacho (615): 36-38. In Japanese.
Ueta, M. & Masterov, V.B. 2000. Estimation of population trend of Steller’s Sea Eagles by a computer
simulation. In: Ueta, M. & McGrady, M.J. (eds). First Symposium on Steller’s and White-tailed SeaEagles in East Asia. pp. 111-116. Wild Bird Society of Japan, Tokyo, Japan.
Working Group of White-tailed Eagle and Steller’s Sea Eagles (WGWS). 1996. Wintering status of Steller’s
Sea Eagles and White-tailed Eagles in northern Japan. Survey of status and habitat conditions ofthreatened species. pp. 1-9. Environment Agency, Tokyo, Japan.