Rat poison was found in 80 percent of the 133 eagles tested by researchers in the U.S. between 2014 and 2018
Bald Eagle
Bald eagle
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Rat poison has been discovered in the bodies of over 80 percent of American eagles, according to findings from a new study published Wednesday.

The study, published in the journal PLOS One, found that anticoagulant rodenticide compounds — another name for rat poison — were found in approximately 82 percent of the 133 eagles tested by researchers between 2014 and 2018.

Of the 116 bald eagles tested, 96 had been exposed to rat poison, while 13 of the 17 golden eagles tested also had rat poison in their systems.

The researchers who examined the eagle carcasses over the four-year time period were unable to establish how the poison got into the eagles' bodies.

"Although the exact pathways of exposure remain unclear, eagles are likely exposed through their predatory and scavenging activities," said study author Dr. Mark Ruder, an assistant professor at the University of Georgia College of Veterinary Medicine's Southeastern Cooperative Wildlife Disease Study, according to CNN.

Researchers also learned that four percent of the birds examined died from rat poison. Per the study, tall the birds showed signs of internal bleeding, which is caused by blood clots as a result of the poison.

Bald Eagle
Credit: David Rosenblum/Icon Sportswire via Getty

Scott Edwards, a director of graduate studies and zoology professor at Harvard University, who was not involved in the study, told CNN that Americans should avoid rat poison. He also called humans a threat to the eagles.

"Humans need to understand that when those compounds get into the environment, they cause horrible damage to many species, including our national symbol, the bald eagle," Edwards reportedly said.

Despite the threat of rat poison, the American bald eagle — which was once listed on the endangered species list — has seen its numbers quadruple since 2009, according to a recent report by the U.S. Fish and Wildlife Service.

The species grew to 316,700 birds and 71,400 nesting pairs in the lower 48 states during the 2019 breeding season, per the report.