Sports

Lead poisoning in eagles: The hunters’ role

Wildlife rehabilitator Robyn Graboski, left, and Penn State senior Kali Gulliver tube-feed a lead-poisoned bald eagle at Centre Wildlife Care.
Wildlife rehabilitator Robyn Graboski, left, and Penn State senior Kali Gulliver tube-feed a lead-poisoned bald eagle at Centre Wildlife Care. For the CDT

The recovery of the bald eagle, our national symbol, has been a wildlife success story, particularly here in Pennsylvania where numbers are soaring.

However, even as eagle numbers increase, a new threat is showing its face: lead toxicity.

Research suggests the poisoning is coming from the ingestion by scavenging eagles of lead shot, bullet fragments or lead fishing weights.

I grew up in a hunting family where grouse, rabbit and venison were frequently on the menu, and maybe you did, too. During my life, I have possibly ingested dozens of lead pellets and bullet fragments — and I am still alive.

So, why is it killing eagles?

If a mammal, such as a coyote or human, eats a lead particle, it quickly passes through their digestive tract and usually causes little harm. Birds are not so fortunate.

According to Pennsylvania Game Commission wildlife veterinarian Dr. Justin Brown, if an eagle, other raptor or duck ingests a piece of lead, it is usually retained in the bird’s gizzard. Once there, digestive acids dissolve the lead and the bird often suffers a slow and painful death. One or two lead pellets could kill a mature eagle.

Brown, who presented data to the game commissioners at their Sept. 25 meeting, cited lead toxicity as a major killer of eagles in the state. During the past 10 years, 202 dead bald eagles were tested and low levels, what Brown referred to as “background” amounts, showed up in 142 birds. Four had a sub-lethal amount of lead in their system, and 56 had clinical or severe levels — enough to kill the bird or cause serious impairment.

“Eagles with lead toxicity are progressively weakened, they eventually refuse to eat, lose muscle coordination and they might become blind,” Brown said.

“It is not a humane death,” noted licensed wildlife rehabilitator Carol Holmgren of the Tamarack Wildlife Center in Crawford County. “It is a slow and painful death.”

It is not a humane death. It is a slow and painful death.

Carol Holmgren, wildlife rehabilitator from Tamarack Wildlife Center, Crawford County

Tamarack has treated six bald eagles for lead poisoning in the past six weeks, and all but one died. Locally, Centre Wildlife Care is currently treating four birds for lead poisoning, including one bald eagle.

While 32 percent of the eagles in Brown’s data set died from some sort of trauma, such as collisions with vehicles, many probably got into trouble because of the effects of lead in their system.

“Most of the birds that we find to have high lead levels were admitted because of some other type of trauma. The lead leaves them weak and less aware of their surroundings,” said Robyn Graboski of Centre Wildlife in Port Matilda.

“I am still analyzing the (Game Commission) data,” Brown said, “... but I do know that there certainly were animals found dead due to trauma from being hit by a car or a train that had high enough levels of lead in their livers to be consistent with disease.”

Not included in Brown’s data are 10 bald eagles with toxic lead levels that have been brought to Pennsylvania wildlife rehabilitators this year. All but two have died.

Not something new

In 1991, the U.S. Fish and Wildlife Service banned the use of lead ammo for waterfowl hunting. Thousands of tons of lead pellets were being deposited in wetlands by duck hunters every year. As a result, millions of ducks were dying from lead poisoning after they ingested the spent shot. The highest numbers of poisoned ducks were divers or dabblers — those who were picking the lead pellets up off of the bottom of the marshes.

Compared to lead-caused mortalities in the 1980s, the USFWS estimates 500,000 to 1 million waterfowl are saved each year by the ban. Many hunters looked at the science and supported the ban, while others complied — though kicking and screaming. In reality, the ban has benefited wildlife and hunters.

I have never encountered anyone today who claims the 1991 lead-shot ban was an anti-hunting move or “back-door gun control.” The ban has saved millions of waterfowl and probably thousands of birds, such as bald eagles, that scavenge on dead ducks. Hunting continues and people own more guns today than they did in 1990.

Ducks Unlimited, the premiere waterfowl conservation group, has conserved over 3.8 million acres of duck habitat since 1937. DU is a science-based organization, and more waterfowl hunters belong to DU than any other organization.

“We absolutely support the ban on lead shot for waterfowl hunting,” DU chief scientist Tom Moorman said. “We recognize that a lot of birds are being saved every year. That USFWS estimate might even be conservative.”

Enough for the history lesson. What about today? As noted, mounting evidence suggests that many raptors, including bald eagles, are dying because of the use of lead rifle bullets, lead shot, lead fishing lures and sinkers.

Some hunters have voluntarily made the switch to non-lead ammo for part or all of their hunting. The science is strong enough for Moorman: he will be switching to copper bullets for all of his deer hunting this fall.

Retired forester Mary Hosmer, from Johnsonburg, is very active in The Ruffed Grouse Society. She hunts 20 to 25 days per year, and chose years ago to stop using lead for any of her small game hunting.

“I still shoot lead at the range, but I switched to using non-toxic bismuth for small game,” Hosmer said. “Yes, it costs more, but I feel better about using bismuth. It is better for the environment.”

Charlie Burchfield, an outdoor communicator from DuBois, has harvested several deer using copper rifle ammunition.

“I have been testing the performance and ballistics of non-lead ammo for quite some time,” Burchfield said. “Copper rifle bullets can be extremely effective. For hunters, it should be a matter of choice.”

Looking at the science and communicating with biologists, wildlife rehabilitators and a veterinarian, this outdoors write and hunter has made a choice: I will be using non-lead ammo for deer hunting this fall.

What can you do?

If you hunt big game with a common caliber, such as .243, .270, .30-06, .308, .300 Winchester or a few others, you can purchase ammo loaded with copper bullets. I purchased Federal Power-Shot online from Bass Pro Shop — about $27 for a box of 20, with a $2.50 rebate. Non-lead shotgun ammo is available locally. Copper bullets are also available for reloaders. Check locally or order online.

Wildlife rehabilitators Peggy Hentz and Greg Nason, from Red Creek Wildlife Center, testified at the game commission meeting last week. They suggested, since non-lead ammunition is not available in all calibers, hunters using lead bullets should bury or cover entrails with branches and groundhogs should be buried. Since bald eagles and hawks locate food to scavenge by sight, covering remains keeps the raptors from locating them.

Education is the key, not legislation. Hunters have been conservation leaders. I hope they will demonstrate that leadership once again to benefit raptors.

Mark Nale, who lives in the Bald Eagle Valley, is a member of the Pennsylvania Outdoor Writers Association and can be reached at MarkAngler@aol.com

  Comments