Lead bullets are killing more than just hunting game in the US

Bald and golden eagles are being decimated by frequent and widespread lead poisoning from hunters’ guns across the US, a new study shows.

Examining the carcasses of 1,210 dead eagles across 38 US states over eight years, scientists from the US Geological Survey, Conservation Science Global (USGS) have found that half of the birds presented high levels of lead – a poison they had likely ingested by consuming contaminated deer.

It’s the first study to show the consequences of lead poisoning on predatory birds on such a wide scale.

According to the USGS scientists behind the study, the repeated exposure to lead is hindering the population growth of both bald and golden eagles, which are protected species in the US and just recently made a comeback from the brink of extinction.

In the twentieth century, the two species were disappearing due to the widespread use of the insecticide dichlorodiphenyltrichloroethane, which was later banned.

The two species significantly increased their numbers in recent decades. While bald eagles are endemic in the US and their population is still growing yearly by an average of 10 per cent, lead poisoning threatens to tip the number of golden eagles in the country towards a dramatic decline.

A study by researchers at the Department of Public and Ecosystem Health at Cornell University in New York has estimated that ingesting hunters’ bullets left in wildlife have stunted the birds’ population growth by 6.3 per cent for males and 4.3 for females.