Mögliche Auswirkungen von Bleivergiftungen auf die Seeadlerpopulation im Persina Naturpark, Bulgarien

Stipendiatin/Stipendiat: Emil Todorov


The White-tailed Sea Eagle is a flagship species as well as a symbol for nature protection in Europe.
Lead poisoning in waterfowl has been known in Europe and the United States for a long time. And is caused by the consumption of lead left in the environment as the result of hunting activities. In Japan, the problem became widely known in 1989 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 lead pellets, 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 lead pellets (Elliott et al. 1992, Locke et al. 1992). Similar cases of lead poisoning caused by ingesting contaminated waterfowl have been found in Japan in Steller’s Sea Eagles H. pelagicus in 1988 (R. Shimura unpublished) and 1996 (K. Saito unpublished).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, when lead bullet fragments in the remains of deer are consumed by scavenging eagles.
White-tailed Eagle and other scavenging bird species are threatened by the ingestion of lead bullet fragments taken up with the remains of shot game animals. Conventional hunting rifle bullets are lead-based. Although lead-free alternatives exist they are seldom used because of their allegedly minor killing ability.

Scientific state of knowledge

The White-tailed Eagle is classified as “Least concern” in the IUCN Red List. In Europe, the breeding population is estimated to number 5,000-6,600 breeding pairs, equating to 15,000-19,800 individuals (BirdLife International 2004). Europe forms 50-74% of the global range, so a very preliminary estimate of the global population size is 20,300-39,600 individuals, although further validation of this estimate is needed. In Bulgaria it is priority for conservation threatened species (Biodiversity Act, Annex 2), protected over the whole territory of the country (Biodiversity Act, Annex 3). Threats that affect this species include loss and degradation of wetlands, human disturbance and persecution, environmental pollution, collision with wind turbines and indiscriminate use of poisons. Modern forestry methods reduce the availability of suitable nesting habitat.

The BSPB has been gathering data on the species and taking conservation actions for it for more than 15 years. During the last 5 years BSPB studied intensively the eagle’s distribution in Bulgaria and especially its main breeding sites within the territory of Persina Nature Park. The coordination of the activities is taken by the BSPB Svishtov Office.
In 2011 I established cooperation with the Lebniz Institute for Zoo and Wildlife research in Berlin, Germany. Experts from this institute came to Bulgaria and help us to put two satellite transmitters on young eagles. Now we are in the process of collecting the data about the eagle’s movements. In parallel, we began to working with hunting organizations to gather information on the number of game animals in the area. The region is preferred by the hunters during the winter season, because its hold big numbers of game animals and waterfowls. We believe that lead poisoning in this area can be very high and up to this moment there is lack of information about this threat.

Main goal

In order to fill in knowledge gaps about the White-tailed eagle home range we will produce a map with their movements, their hunting territory, and their roosting areas. Therefore the main goal of my internship would be to study some methods and tools for assessing of the possible impact of lead intoxication of the eagles.
As a result I would like to produce an investigation about the potential impact of lead intoxication of White-tailed eagles along the Danube River. I believe this study will help to choose the best and most appropriate conservation measures for the protection of scavenge birds. In Germany I found many respected scientists who work over the lead poisoning especially Dr. Oliver Krone who is one of the best White-tailed eagle’s experts with many scientific publications and great experience.

Reasons for choosing this topic
The motivation for choosing exactly this topic for my internship stay in Germany comes as result of the following important considerations.
? The White-tailed eagle is on top of the food pyramid and an ideal indicator of the state of the environment;
? There are no any investigations about the lead poisoning in SE Europe and in the same time this threat is marked by the European Species Action Plan as high importance;
? White-tailed eagle have good breeding and wintering population in the project area along the Danube;
? An internship stay in Institute of Zoo and Wildlife Research has a team of experts who would help me to do these studies;

Project objectives:
The objectives of the internship:
? Writing a project proposal for presenting the results of my investigations for potential impact of the lead poisoning of eagles population;
? Preparation of a scientific paper for the White-tailed eagle using the knowledge gained during the internship;

In order to fulfill the objectives of my internship I am going to use different methods.
First, I will have to do thorough desk research for determining all existed literature about this topic. Most of the information is available in the Institute of Zoo and Wildlife Research, but I will try to find more published information about this study. After that, I will do survey on the knowledge and expectations of hunters towards the toxicity of lead versus lead-free ammunition and of current hunting practise regarding the use of lead-free ammunition, including protected areas. In order to create the analyses of the potential impact I will collect and analyse all available field data from the region.

Literature cited

ELLIOTT, J.E., Langelier, K.M., Scheuhammer, A.M., Sinclair, P.H. & Whitehead, P.E. 1992. Incidence of lead poisoning 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.
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.
KUROSAWA, N. 2000. Lead poisoning in Steller’s Sea Eagles and White-tailed Sea Eagles. First Symposium on Steller’s and White-tailed Sea Eagles in East Asia UETA, M. & MCGRADY, M.J. (eds) ©Wild Bird Society of Japan, Tokyo Japan. pp. 107-109
KRONE, O. (2011). Killing capacity of lead-free and lead-based rifle bullets on ungulates in normal hunting conditions. Der Seeadler als Indikator. Leibniz-Institut für Zoo- und Wildtierforschung (IZW). Berlin, Germany, p. 21

01.05.2012 - 31.10.2012

Leibniz-Institut für Zoo- und Wildtierforschung im Forschungsverbund Berlin e. V.

Dr. Oliver Krone

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