Nearly 50 per cent of bald and golden eagles in north America have faced widespread and frequent lead poisoning, impacting both species’ population, according to a report.
Poisoning at the levels found in the study is causing population growth rate to slow for bald eagles by 3.8 per cent and golden eagles by 0.8 per cent annually.
“Studies have shown lethal effects to individual birds, but this new study is the first to show population-level consequences from lead poisoning to these majestic species at such a wide scale,” said Anne Kinsinger, US Geological Survey, Associate Director for Ecosystems.
The report published in the journal Science looked at samples from 1,210 eagles over 38 US states, including Alaska from 2010 to 2018.
The findings also showed that nearly 50 per cent of the birds sampled showed evidence of repeated exposure to lead.
Both eagle species are scavengers and use dead animals as a food source round the year, but particularly rely on them during the winter months when live prey is hard to find.
Lead poisoning typically occurs when an eagle eats lead ammunition fragments lodged inside an animal carcass or in gut piles.
The frequency of chronic lead poisoning found in both species increased with age because lead accumulates in bone, as eagles are repeatedly exposed to heavy metal throughout their lives, the researchers said.