NEWS

Lead level high in few eagles, Iowa State study finds

Mike Kilen,
mkilen@dmreg.com

Only a small fraction of bald eagles suffer from high levels of lead exposure, according to an Iowa State University study released Friday.

It’s a controversial subject — raptor rehabilitators in Iowa have found that most bald eagles that arrive sick or injured at their facilities are poisoned by lead from ammunition, and they have called for ending the sale of shot and slugs made of lead.

“We found very few (wild) eagles had high levels of lead exposure, and a lot of the samples had small amounts,” said Julie Blanchong, associate professor of natural resource ecology and management, who led the study.

Prior to the two-year study, which began in 2011, data on lead levels came from birds in rehabilitation centers, where the exposure was considerably higher.

“It raised a question: Does that represent the overall population?” Blanchong said.

Researchers gathered excrement samples from around 110 Iowa nests twice a year and tested them for lead, comparing them with levels in three rehabilitation centers, which were much higher. Blood samples are preferred for testing, but the method is impractical to gather in wild birds.

Lead in bald eagles, often thought to occur through scavenging carcasses shot by hunters, disrupts their bodily functions and development, and can lead to death.

Researchers say no lead levels are good for birds. But it’s cautious good news for a population that has steadily grown in Iowa from one bald eagle nest in 1977 to more than 250 today.

During the monitoring, they also found 83 percent of the nests produced at least one offspring, “the highest success rate we have ever found,” said ISU’s Stephen Dinsmore, who also worked on the project.

But Kay Neumann of Saving Our Avian Resources, a raptor rehabilitator in Dedham, said the research is “like walking down the street, checking every teenager to see if they died in a car accident. You might not find one, but it is one of the leading causes of mortality.”

She said of 280 bald eagles that have come into her facility, 60 percent have had exposure to lead, which led directly to their illness or may have contributed to their injuries because of the effects on their systems. She said studies have shown it is the leading cause of bald eagle death at rehab sites.

“And these are only the ones we are finding and the public is getting to us,” she said. “If you are a wild eagle and you can’t see well because of lead poisoning or your stomach hurts, you might starve to death.

“We should always be proactive with conservation, and this is an easy thing to do. We don’t have to poison eagles.”