Bald eagles are being affected by lead poisoning. A study performed by the Department of Public and Ecosystem Health at Cornell found that between 1990 and 2018, birds are eating hunters’ gunshot ammunition. This has decreased their population by 4% to 6%. 

Scientists looked at population regrowth numbers for bald eagle populations across the Northeast. They found that a majority of hunters take the meat of an animal and leave the contaminated organs. Any animal who then eats these remains has a chance of getting poisoned. They get lead poisoning from the contamination left from the animals being shot. There are types of bullets, such as copper-based ammunition, that would not have effects on animals. 

The last time bald eagles were threatened as they are now was during World War II. The use of dichloro-diphenyl-trichloroethane greatly declined the bald eagle population until the Endangered Species Act was enacted in 1973. Soon after, the population began to increase again. The bald eagle population has quadrupled between 2009 and 2021. However, scientists have estimated that bald eagle growth rates are still suppressed by 4.2% for females and 6.3% for males. 

Krysten Schuler, assistant research professor in the Department of Public and Ecosystem Health at Cornell University and senior author on the study, said, “Even though the population seems like it is recovered, some perturbation could come along that could cause eagles to decline again.”