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Study Finds Elevated Lead Levels In Bitterroot Valley Eagles

A screen capture from a 2019 Montana Fish, Wildlife and Parks video shows a golden eagle picking at an animal carcass while two magpie stand nearby.
Montana Fish, Wildlife and Parks
A screen capture from a 2019 Montana Fish, Wildlife and Parks video shows a golden eagle picking at an animal carcass.

A recent studyfrom RaptorView Research Institute in Missoula found that most golden eagles that wintered in the Bitterroot Valley between 2011 and 2018 had elevated levels of lead in their blood. RaptorView Executive Director Rob Domenech says lead in the birds is related to hunters using lead bullets.

In this video taken by researchers at MPG Ranch in Florence, a golden eagle pecks at an elk carcass that didn’t make it through a recent winter. The bird flies away after eating.

Researchers caught 91 golden eagles that wintered in the Bitterroot Valley and tested the level of lead in their blood. More than 90% of the birds had lead in their systems. Eight of the birds had enough lead in their blood to cause health problems.

Domenech says he was shocked to learn that so many golden eagles in the area had such elevated lead levels. 

“It just kills us when we see a big, beautiful female golden eagle that knows how to survive, knows how to raise young successfully, knows how to hunt, eat some poisoned piece of meat and die.”

Federal guidance for the use of lead ammunition on certain federal lands has shifted in recent years. 

President Barack Obama’s administration created a plan to phase out the use of lead ammunition on federal lands in 2017, just before he left office. Former Interior Secretary Ryan Zinke reversed the ban weeks later when President Donald Trump entered the White House. 

Joe Biden’s administration has not announced plans to reinstate the ban on lead bullets. A spokesperson for the Department of Interior declined to comment for this story. 

Studies published over the last decade have linked lead-based ammunition to health risks posed to humans and wildlife. But some hunting groups have opposed a ban on lead bullets because switching to copper could be more expensive.

In 2019, Montana Fish, Wildlife & Parks released a video with MPG Researcher Mike McTee encouraging Montana hunters to consider using copper bullets

“We’re to the point that the evidence of lead poisoning in wildlife from lead bullets is so overwhelming it’s more of a social issue,” McTee said in the video. “It’s about outreach and it’s about communication.”

Amy Seaman, director of policy and science for Montana Audubon, says she doesn’t see any action at the state or federal level to put new regulations on the use of lead ammunition. She says new regulations would reduce the number of golden eagles that ingest lead.

“It would be great to have the state take a stronger stance.”

While studies have raised concerns about the impact of lead fragments on wildlife more broadly, golden eagles are at the center of research in Montana. 

Domenech says some experts worry golden eagles could go extinct unless human behavior, including the use of lead bullets, changes. Researchers say wind turbines, vehicle collisions and electrocution from power lines also kill golden eagles each year. 

It’s illegal to kill a golden eagle, according to the Bald and Golden Eagle Protection Act of 1962. 

Mary is a UM School of Journalism student and MTPR student reporter.
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