A bald eagle takes flight from a sandbar with its meal in its talons off of Maine on August 22, 2011.
Pat Wellenbach.
The bald eagle population was almost wiped out by a pesticide. Researchers at Cornell University have found that the resilience of American icons is hampered by lead.
The population of bald eagles in the Northeast has grown at a slower rate than in the lower 48 states because of the use of lead bullets.
The dead animals can be contaminated with lead if they are left behind by hunters. The research spans decades of data, between 1990 and 2018, and covers seven states: Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, New York and Vermont.
The study focuses on bald eagles, but it could have implications for other animals that are also known to feed on carcasses.
The Cornell Wildlife Health Lab has a lot of data on bald eagles. "They're the poster species that we're using for this issue because we don't have the same amount of data to do this type of analysis on other species."
The bald eagles were almost wiped out by the use of the pesticide DDT, which was hailed as an "American success story" by the U.S. Fish and Wildlife Service. The eagles were included on the list of threatened species after the pesticide was banned. Bald eagles were removed from the list.
Lead didn't help the eagles' recovery, but it didn't stop them.
When a hunter shoots a deer, the bullet goes into small pieces. If a hunter dresses the carcass by removing its internal organs, the organs left behind can carry lead fragments. The eagles feed on lead contaminated organs.
The acid in eagles' stomachs breaks down the lead, which causes it to circulate in their bodies.
"It's a source of mortality that's very familiar to me," he said. The eagles are picking up lead from the environment that we put there, and hunters have a choice in what they use.
The use of other types of bullets, such as copper, could help keep lead out of bald eagle habitats. The eagle population could be kept from being impacted by the contaminant if the organs of a carcass shot with lead were buried.
"This is not an anti-hunting effort," he said. We're trying to emphasize the choice and the education components.
Washington has also heard of the use of lead.
The director of fish and wildlife banned lead on national wildlife refuges on the last day of the Obama administration. Donald Trump's first interior secretary overturned it a few weeks later.
Ted Lieu introduced a bill in July of 2020 that would ban the use of lead on US Fish and Wildlife Services land. The bill was not passed in Congress. In March 2021, a member of the Maine Legislature introduced a bill. The bill died as well.
Lieu told a radio station that lead is a deadly toxin. It's also deadly to animals and we shouldn't just be spreading it all over the place.
The researchers publicly shared their software so others could use it to investigate other species.
We didn't know what we were going to find when we started. For as long as I can remember, it's been a big question in my career.
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