Poisoning caused by preying on or scavenging animals shot by hunters using lead ammunition has left the populations of many raptors far smaller than they should be, according to the first study to calculate these impacts across Europe.
When birds like eagles and Red Kites scavenge carcasses or eat injured animals with fragments of toxic lead from gun ammunition embedded in their bodies they can become poisoned, suffering slow and painful deaths. Smaller doses have been shown to alter behaviour and physiology.
Now, scientists from the University of Cambridge have used data on lead levels in the livers of over 3,000 raptors found dead in more than a dozen countries to calculate the extent to which poisoning by lead ammunition has affected Europe’s raptor populations.
Researchers estimate that, for ten raptor species, poisoning from lead ammunition alone has resulted in an absence of around 55,000 adult birds from European skies.
Worst affected are species like eagles that are naturally long-lived, rear few young per year and breed later in life. However, even populations of species familiar to bird-watchers across countries like the UK, such as the Common Buzzard and Red Kite, would be significantly bigger were it not for lead ammunition.
For example, the study suggests that Europe’s White-tailed Eagle population is 14% smaller than it would have been without more than a century of exposure to lethal levels of lead in some of its food.
This is closely followed by the Golden Eagle and Griffon Vulture with populations 13% and 12% smaller than they would otherwise have been. Northern Goshawk numbers are 6% smaller, and both Red Kite and Western Marsh Harrier populations are 3% smaller.
Common Buzzard populations are 1.5% smaller, but this equates to almost 22,000 fewer adults of this widespread species, say the researchers.
They estimate that the overall European population of ten raptor species is at least 6% smaller than it should be, solely as a result of poisoning from lead ammunition. The findings are published today in the journal Science of the Total Environment.
