Lead hunting bullets in carrion are killing eagles and other scavenging animals, and in Wisconsin at least, it mostly stems from deer hunting, and more and more wildlife experts are raising the alarm.
“Modern hunting bullets are designed to mushroom quickly to transfer energy through hydrostatic shock and cause quick, humane kills with a properly placed shot, something that firearms authorities agree that they do reliably and well,” writes the Ashland Daily Press of Wisconsin. “However, recent research has shown that traditional lead-cored bullets encased in copper-based gliding metal jackets quickly fragment in the body of the deer, spraying lead throughout, as far as 18 inches from the point of impact. It is not unusual for even premium quality hunting ammunition to lose up to half of its original mass upon impact with a deer.”
It contributed not only to the discovery of lead fragments in 53 of 95 venison packages X-rayed in South Dakota food pantries in 2008, but also to the realization that much lead is left behind in the piles of innards that hunters discard once they are done dressing the deer, or other game, in the field. Devoured by scavengers, including eagles, the piles become sources of toxins, not nutrition.
An adult bald eagle can be poisoned by just three-tenths of a grain of soluble lead, the Ashland Daily Press said, quoting Wisconsin Department of Natural Resources Biologist Todd Naas.
“Lead poisoning in bald eagles peaks in late fall and early winter, during and right after deer hunting season,” wildlife biologist Karin Kozie told the newspaper after she and her husband, National Park Service wildlife biologist Bill Route, were contacted by people who had found a lead-poisoned, nearly starved, bald eagle in Bayfield County, Wisconsin. The bird’s lead level was about twice as much as was treatable, and it had to be euthanized, the Ashland Daily Press reported in late January.
“Eagles and other predators feed on deer gut piles filled with lead bullet fragments,” Kozie said. “But it’s not just eagles that are affected. We’re now starting to understand that most lead bullets shatter so explosively on impact that they end up in far larger portions of the deer meat than we thought. So we are eating lead as well.”
The only way to stop such poisonings is to remove the lead from big-game bullets, sources told the Ashland Daily Press.
“An eagle with lead poisoning is very likely to die,” said Pat Redig, a veterinarian with the University of Minnesota’s Raptor Center, to the newspaper. “Even if the bird responds to treatment and doesn’t die as a direct result of the poisoning, the permanent damage to his heart or brain will significantly impede his ability to survive in the wild.”
Such deaths are not relegated to the upper Midwestern United States. In early January a lethargic bald eagle was brought into the Alaska Raptor Rehabilitation Center in Sitka, where it died two days later, the center’s first-ever case of lead poisoning, the radio station KCAW reported on February 5. And California is battling the same issue regarding condors.
Below, a quick look at what lead poisoning does to eagles, from the Raptor Center in Minnesota.