Swallowed lead ammunition threatens birds of prey – wissenschaft.de

Hunting shots with additional damage: Dead or injured victims carrying lead ammunition are fatal to many raptors in Europe, research shows. The data and extrapolations collected by the scientists show that the use of lead-containing ammunition for hunting has significantly reduced the populations of some species of birds of prey. Therefore, the use of non-toxic ammunition should now be consistently enforced, the researchers demand.

Metal pellets made of lead-containing alloys: These traditional projectiles still fire from many shotguns and rifles used to hunt rabbits, pheasants and the like in Europe. In fact, it was already known that this ammunition could indirectly cause problems for raptors: by eating carrion or capturing injured animals, they could ingest lead in lethal or harmful amounts. X-ray images of wild ducks and wild geese illustrate the possibility of swallowing: about a quarter to a third of the living birds have shattered into their bodies.

However, it is not clear to what extent contaminated feed actually affects populations of frequently endangered species of birds of prey. In order to be able to better assess the importance of this factor, scientists from the University of Cambridge and the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in Berlin have now collected extensive data in Europe and performed calculations.

Quantified for the first time

They used information from a study of the livers of thousands of raptors found dead in 13 countries since the 1970s. They then statistically linked lead exposure data to the average number of hunters per square kilometer for each country. In turn, the researchers also used this relationship to predict poison rates in countries where there is no data on liver-enriched lead – but where the density of hunters is known. The scientists then used population models to estimate how large the population of European raptors would be without the use of lead ammunition.

As reported by the scientists, their results show: Due to the long tradition of using lead ammunition, the European skies in total are missing at least 55,000 birds of prey. Long-lived species are particularly affected, as they raise only a few young each year and only reproduce later in life, when lead levels often reach critical levels. In particular, the results show that Europe’s white-tailed eagle population is 14% smaller than it would have been without dietary lead contact, followed by the golden eagle and griffon vulture, which have decreased by 13% and 12% respectively. The study shows that this also applies to the more common species: the hawk population has declined by 6% and the red kite and marsh harrier populations by 3%. The buzzard population continues to decline by 1.5 percent. As scientists emphasize, even this corresponds to almost 22,000 specimens of this widespread species.

Non-toxic alternatives required

“We can now see the significant impact that lead poisoning can have on the populations of some of our most vulnerable bird species – birds of prey protected by EU rules and the UK Wildlife and Countryside Act,” said lead author Debbie Pain of the University of Cambridge. That is why she and her colleagues are now stressing the need to refrain from the use of lead ammunition when hunting in Europe. According to the researchers, there are also many non-toxic and well-functioning alternatives available. As the appeals for a voluntary waiver have apparently not worked so far, the legislature is asked, the researchers said.

Currently, only Denmark and the Netherlands have enacted a nationwide ban on the use of lead shot. So far, both the European Union and the UK are considering only a broader legal ban on all ammunition containing lead. Regarding Germany, co-author Oliver Krone of Leibniz-IZW says: “Only 4 out of 16 federal states have banned the use of lead rifle ammunition during hunting. In addition, lead munitions are prohibited in all Länder in state forests and in several Länder in state forests, as well as in national parks and nature reserves. However, this mosaic leaves plenty of room for the continued use of lead ammunition, also because the vast majority of hunting grounds, such as forests and agricultural land, are privately owned. Partial solutions to the problem will not be enough to end the negative effects of lead poisoning on the population of birds of prey in Germany – a nationwide solution to the problem would be needed, says Krone.

Source: University of Cambridge, Leibniz Institute for Zoo and Wildlife Research, Article: Science of The Total Environment, doi: 10.1016 / j.scitotenv.2022.154017

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