Hunting shots with collateral damage: Dead or wounded prey carrying lead ammunition is fatal to many birds of prey in Europe, a study shows. The researchers’ data collection and projections show that the use of lead-containing ammunition for hunting has significantly reduced the populations of some species of birds of prey. The use of non-toxic ammunition should therefore now be consistently enforced, the scientists demand.
Metal pellets made from alloys containing lead: These traditional projectiles still fire from many shotguns and rifles used for hunting rabbits, pheasants and the like in Europe. In principle, it was already known that this ammunition can indirectly cause problems for birds of prey: By eating carrion or by capturing wounded animals, they can ingest lead in fatal or damaging quantities. X-rays of wild ducks and wild geese illustrate the potential for swallowing: around a quarter to a third of living birds have shot pellets in their bodies.
However, to what extent the contaminated feed actually affects the populations of the often endangered bird of prey species was unclear. In order to be able to better assess the importance of the 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 carried out calculations.
Quantified for the first time
They used information obtained from examinations of the livers of thousands of birds of prey found dead in 13 countries, conducted since the 1970s. They then statistically related the lead exposure data to the average number of hunters per square kilometer in each country. In turn, the researchers used this relationship to also predict the poisoning rates in countries where there is no data on lead enriched in livers – but where the hunter density is known. The researchers then used population models to estimate how large the European bird of prey population would be without the use of lead ammunition.
As the researchers report, their results show: Due to the long tradition of using lead ammunition, the European sky is missing a total of at least 55,000 birds of prey. Particularly affected are long-lived species that raise only a few young each year and only breed later in life, when lead levels often reach critical levels. Specifically, the results show that Europe’s white-tailed eagle population is 14 percent smaller than it would be without dietary lead exposure, followed by golden eagle and griffon vulture, which are down 13 percent and 12 percent, respectively. The study shows that more common species are also affected: the population of hawks has fallen by six percent and the population of red kites and marsh harriers by three percent. The common buzzard population is still down by 1.5 percent. As the researchers point out, even this corresponds to almost 22,000 specimens of this widespread species.
Use of non-toxic alternatives required
“We can now see how significant the impact lead poisoning can have on populations of some of our most vulnerable bird species – raptors protected by EU regulation and the UK Wildlife & Countryside Act,” said lead author Debbie Pain of the University of Cambridge . That is why she and her colleagues are now emphasizing the demand to refrain from using lead ammunition when hunting in Europe. According to the scientists, there are also a number of non-toxic and well-functioning alternatives available. Since calls for voluntary renunciation have apparently not worked so far, the legislator is asked, say the researchers.
Currently only Denmark and the Netherlands have enacted a nationwide ban on lead shot. So far, both the European Union and the United Kingdom are only considering a broader legal ban on all lead-containing ammunition. As for Germany, co-author Oliver Krone from the Leibniz-IZW says: “Only 4 out of 16 federal states have banned the use of leaded rifle ammunition for hunting. In addition, lead ammunition is banned in all federal states in the state forest and in several federal states in the state forests as well as in national parks and nature reserves. However, this patchwork leaves a lot of room for the continued use of lead ammunition, also because the vast majority of hunting areas such as forests and agricultural land are privately owned. Partial solutions to the problem are not enough to end the negative effects of lead poisoning on the raptor population in Germany – a nationwide solution to the problem would be necessary,” says Krone.
Source: University of Cambridge, professional article: Science of The Total Environment, doi: 10.1016/j.scitotenv.2022.154017