Eagles in US Face Widespread Lead Poisoning, New Study Says

Scientists say the ongoing trend may wipe out the work of conservationists, who have for decades fought to restore the population of bald eagles, which were placed on the list of endangered species in the second half of the 20th century.

The national bird of the United States is under threat, as a new study conducted by local scientists has revealed that eagles have been suffering from lead poisoning. Researchers say they examined 1,200 bald and golden eagles across 38 US states. They tested their feathers, bones, internal organs, and blood and discovered that half of the animals had signs of chronic lead poisoning.

Up to 33 percent of bald eagles and up to 35 percent of golden eagles showed signs of acute poisoning.

"Lead can affect every single system of an eagle’s body — their respiratory system, their digestive system, their reproductive system", said Dr Vincent A. Slabe, the lead author of the study and a research wildlife biologist for Conservation Science Global in Montana.

The researchers say birds with repeated exposure suffered from weakness, lesions, convulsion, and paralysis. The study also showed that that poisoning led to the slowing down of population growth rates by around four percent for bald eagles and one percent for golden eagles.

"These percentages seem small, but, over time, thousands and thousands of individual birds are being removed from the population [due to lead poisoning]", said Todd E. Katzner, a research wildlife biologist at the US Geological Survey.

The researchers believe that hunting activity has led to the ongoing problem. Eagles scavenge on carcasses of animals that have been shot by hunters. According Todd Katzner, it takes a tiny fragment of a bullet to cause severe damage to a bird's health. "Something the size of the head of a pin" can kill an animal, said the biologist.

The scientists discovered that the concentrations of lead in eagles' digestive systems spiked in wintertime, when birds were less likely to find prey and more likely to be scavenging for a meal.

Researchers have known about the potential danger of lead ammunition, but this study is the first of its kind to look into the effects of lead poisoning on the bird populations. The scientists say they hope their findings will persuade hunters to switch to copper bullets.

Some hunters have already stopped using lead bullets since learning about the damage they can cause.

Laura Hale, president of the Badger Run Wildlife Rehab in Klamath Falls, whose organisation has also treated different kinds of animals, recalled how in 2018 a hunter contacted them. The man was trying to save an eagle he found in the woods. The bird was unable to fly and was gasping for air. Doctors found that it had become sick after eating meat that contained pieces of lead.

"[The hunter] was horrified. He wanted to stop hunting", Hale said.