Return of White-tailed Eagles to Finland
White-tailed eagles (Haliaeetus albicilla) like all raptors have been actively hunted over long time. Early 1900’s state was even paying for killing of birds. Common attitude was to reduce raptors and all predator animals to increase the populations of their prey animal species. White tailed eagles were seen to be predators for the fish and young seals, at least. Finnish population was already close to extinction when the species was finally protected by law in 1920. However, poaching continued during several decades.
Toxicological problems appear
During 1960’s and 70’s large use of PCB and DDT as well as dioxin and methylmercury were causing serious problems for the top predators like eagles. These fat liquid compounds are concentrated in the food chain and top predators (including large raptors) get the highest amounts of these chemicals from their food.
DDT and PCB decrease the reproduction rate of birds. Cover of eggs become thinner and in extreme cases the thin cover of eggs gets broken from the weight of adult bird. Also, DDT and PCB and other environmental toxins cause developmental disorders in birds. Even if the species was protected the growth rate stayed low over several decades.
WWF establishes a working group to save the population, Natura 2000 network
The observation on the low reproduction rate increased worry among bird enthusiasts and finally in 1973 World Wide Fund for Nature (WWF) established an expert group to help White-tailed eagles. The group started to offer clean food (dead pigs) for the eagles. Also, according to Nature Conservation Act any tree hosting nest of a large bird of prey is protected. In many cases, the nesting trees were in islands and in such cases regional environmental centers made decision to limit any visits to the islands during the nesting seasons. Later, as Finland established Natura 2000 sites, many of these localities were included in this European network of protected areas.
Results from the active conservation
Clean food, awareness growth and different types of protection activities helped the population into a new increase. In 40 years, the population has been growing a lot and nowadays the species is not red listed any more.
Earlier the population was limited to live only at the archipelago of Baltic Sea. Now the species has been spreading to new areas and it is nesting in large areas in the North and North-East Finland.
Young white-tailed eagles are competing for food.
White-tailed eagle is the largest nesting raptor in the Northern Europe. It is majestic species. Wing span of adults can be up to 190 cm.
Petri Ahlroth, Director of the Biodiversity Centre
Finnish Environmental Institute - SYKE
Petri.Ahlroth (at) syke.fi