Because of the use of lead-containing hunting ammunition, raptor populations in Europe are significantly smaller than they actually are.
This is the conclusion reached by a team of German and British researchers.
White-tailed eagles, common buzzards and other birds ingest the toxic heavy metal when they are shot with such ammunition or eat dead animals.
The resulting poisoning led to the disappearance of around 55,000 adult birds from ten raptor species from European airspace, the scientists report in the journal Science of the Total Environment.
Lead ammunition poses a great danger to the entire bird world: According to estimates by the European Chemicals Agency ECHA, 135 million birds in the EU are at risk of lead poisoning - either by swallowing lead shot directly or by eating animals that have lead in their bodies.
Such lead poisoning can result in slow and painful death in animals at high doses, while smaller doses have been associated with physiological and behavioral changes.
Biologists from the University of Cambridge, with the support of the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin, have calculated the extent of the poisoning's effects on birds of prey.
The white-tailed eagle (Haliaeetus albicilla) population is 14 percent smaller than it would have been had it not been for more than a century of exposure to lethal levels of lead in some food sources.
Populations of golden eagle (Aquila chrysaetos) and griffon vulture (Gyps fulvus) are down 13 and 12 percent, respectively, while populations of goshawk (Accipiter gentilis) are down 6 percent, and red kites (Milvus milvus) and marsh harriers (Circus aeruginosus) are down 6 percent. are each three percent lower.
The biologists urgently advocate a ban: "The avoidable suffering and death of numerous individual raptors from lead poisoning should be enough to call for the use of non-toxic alternatives," emphasizes co-author Debbie Pain.