According to scientists at Cornell University’s Department of Public Health and Ecology, the population size of bald eagles is being affected by lead poisoning. One study found that birds were eating hunter bullets, reducing their population growth by 4 to 6%.
For the study, published in the Journal of Wildlife Management, scientists looked at the number of repopulations of bald eagle populations across the Northeast. They found that hunters “dressing” into the field for their prey and leaving contaminated organs in place put the remaining carrion eagles at risk. Other species, including owls, crows, coyotes, foxes, fishermen and bears, also eat carrion, meaning they are all at risk of poisoning.
“We didn’t collect data on other species,” said Krysten Schuler, research assistant professor in the Department of Public Health and Ecosystems at Cornell University and senior author of the study. This is like how we notice eagles. “We’re putting eagles out there as a poster species for this, but they’re not the only species affected.”
Even humans can be affected if they ingest a game species that has lead fragments in it.
The team hopes that this information will inform hunters – and political policy – about ammunition options, such as copper-based ammunition.
The diminishing growth rates of bald eagles have the potential to undo a “cushion layer” for populations that would protect them against unforeseen events such as natural disasters or viruses, the researchers say. West Nile could devastate populations, researchers say.
Eagle populations, which were threatened by the use of DDT during World War II, began to recover after the passage of the Endangered Species Act of 1973. In fact, their population size in the lower 48-year-old group quadrupled between 2009 and 2021.
However, the scientists estimate that the bald eagle’s growth rate is stunted by 4.2 percent for females and 6.3 percent for males.
“Although the population appears to have recovered, some disturbances could have caused the eagles to decline again,” Schuler said.
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https://www.winknews.com/2022/01/14/bald-eagle-population-growth-stunted-by-lead-poisoning-study-finds/ Bald eagles stunted population growth due to lead poisoning, study finds