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Virginia’s bald eagle population is under threat from lead bullets well after the bullets hit their initial targets.
The Wildlife Center of Virginia, where most injured bald eagles are taken for rehabilitation in the Commonwealth, took in 38 bald eagles in 2016, 35 in 2015, and 38 in 2014. Eighty percent of the bald eagles admitted to the center in 2016 had measurable levels of lead. These levels of lead can contribute to bald eagles injuring themselves in other ways, including inhibiting an eagle’s ability to fly properly, according to Director of Veterinary Services Dave McRuer.
“Lead has become an epidemic of a problem,” said Dr. Bryan Watts, director of the Center for Conservation Biology at the College of William and Mary and Virginia Commonwealth University. “It’s become one of the larger threats to the bald eagle population.”
Most bald eagles in Virginia live near the hunting grounds of the Chesapeake Bay and they are especially concentrated along the Potomac, Rappahannock and James Rivers.
Bald eagles with measurable levels of lead in their bodies can “fly drunk,” according to several experts at the Wildlife Center of Virginia.
Measurable levels of lead in a bald eagle can shut down the bird’s gastrointestinal tract, disrupt the nervous system, cause oxygen deprivation and disrupt the bird’s ability to see and fly. The Wildlife Center of Virginia believes lead poisoning to be a contributing factor to incidents of acute trauma, such as an eagle colliding with a motor vehicle or falling from its roost in a tree, according to McRuer.
The toxicity of lead is increased when consumed by wildlife compared to lead shot lodging in muscle tissue because of the exposure to digestive fluids and stomach acids which break the lead down. Lead is more easily absorbed into the bloodstream and disseminated throughout the animal’s entire body, according to a document from the Wildlife Center of Virginia.
As little as 1 part per million of lead in an eagle’s blood is usually lethal, according to the Wildlife Center of Virginia.
“1.1 parts per million, anything more than that and their [bald eagle’s] brain turns to swiss cheese, the optic nerve really does not regenerate, the bird essentially has blind spots or goes completely blind,” McRuer said. “Anything more than 1.1 parts per million and they’re basically not being released. Essentially anything over 1.0 [parts per million] is 99.99% a goner.”
A piece of lead the size of a grain of rice is enough to kill three to four bald eagles, according to McRuer.
“The Wildlife Center is one of the better wildlife rehab places and medical groups in the East,” Watts said. “They are one of the best. They handle most of the difficult cases.”
Virginia’s bald eagle population is at a new high of 1,070 nesting pairs from a low in the 1970s of 33 nesting pairs, according to the Department of Game and Inland Fisheries.
“That’s the first time that Virginia has broken 1000, since we started keeping records in the late 1950s,” Watts said. “It’s beyond what any of us thought the population could reach. The population is maybe on par with what it would have been in colonial times.”
McRuer, The Wildlife Center’s director of veterinary services, said he thinks the deaths of bald eagles from measurable levels of lead in their blood are preventable.
“The scientific community has put up enough overwhelming evidence, that the lead is coming from spent ammunition…The vast majority, especially from scavenging raptors, is from spent ammunition,” he said.
Raptors are a type of carnivorous bird with a hooked beak, strong feet with sharp talons, acute eyesight. Bald eagles are raptors, according to the United States Bureau of Land Management.
President and founder of the Wildlife Center of Virginia Ed Clark Jr. suggested that hunters need to be aware of where and how they dispose of game and field dressings at a bald eagle release at York River State Park in December 2016.
“Having been a hunter my whole life, I never heard anything about this,” Clark said. “I used to be a hunter safety instructor, an NRA certified instructor for the Department of Game and Inland Fisheries, and we always taught our students ‘you’re responsible for your bullet from the instant it leaves the gun until it stops’ and we just need to modify that. Even after that bullet stops it can continue to kill. People don’t go into the woods to deer hunt with the idea they’re going to kill an eagle, too.”
Information about the Center for Conservation Biology’s initiatives to track bald eagles in the Chesapeake Bay region is available here.