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The Deer You Hunted Could Be Killing Michigan Bald Eagles

People who eat venison shot with lead ammo could be at risk, too

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Less than 20 years after being moved off the endangered species list, U.S. bald eagles are again facing a crisis. Now the threat comes in the form of chronic lead poisoning. The cause? Lead ammunition.

Lead is an especially toxic heavy metal when ingested by bald eagles, golden eagles and other wildlife. Eagles, which are natural scavengers, often feed on the remains of animals that have been shot by sportsmen using lead ammunition.

What we know is that it takes a very small amount of lead, around the size of a grain of rice, to affect eagles,” said Doug Craven, natural resource department director for the Little Traverse Bay Band of Odawa Indians (LTBB).


An eagle with lead poisoning may exhibit symptoms like lethargy or poor motor skills but otherwise may look healthy. Lead also affects the cardiac system and gastrointestinal track. It not only can kill them outright but can build up in their system over time, often leading to shorter lifespans, increased health problems and higher risk of traumatic injury.

James Manley is the executive director at Skegemog Raptor Center located in Traverse City, which was established in 2021. The center treats, rehabilitates and releases injured eagles. Upon arrival, the eagles are blood tested for lead exposure by the staff.

“So far we’ve tested 17 bald eagles. Of those, 13 had levels that we would consider in the subclinical poisoning range,” Manley said.

When an eagle eats lead, it shows up in the bloodstream, filters through the liver, and can build up in the bones if the bird eats enough lead throughout its lifetime.


“The last three birds we admitted showed severe acute poisoning, meaning they are over 100 micrograms of lead per deciliter,” Manley said. “One of them actually was 142, another 130, and the third 976.5. When they have acute poisoning at that level, it affects them neurologically and causes permanent damage.”

Two of those birds had to be humanely euthanized.

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How does it happen?

At the moment of impact, a lead bullet fragments into several hundred pieces, traveling throughout the flesh of the carcass, up to 18 inches from the impact site.

“We’ve seen through similar studies that the bullet will create these micro-fragments. Lead is a soft material to begin with, but it’s designed to fall apart, mushroom out. The impact is beyond that wound chamber. The lead will go out farther into different parts of the meat,” Craven said.


Lead fragments are dispersed in the gut pile that’s left behind by hunters. Research indicates this is the primary contributor to lead poisoning in the environment.

Eagle rehabilitators see a spike in lead poisoning shortly after hunting season, then again in the spring when the snow melts and exposes those gut piles.

Wildlife isn’t the only one impacted, these fragments make their way into processed meat and often time go unnoticed by the human consumer.

Lead poisoning impacts their ability to feed and operate

At the Skegemog Raptor Center, eagles with lead exposure over 10 micrograms per deciliter receive treatment. If it’s between 10 and 20 micrograms, they treat with an oral collations drug; anything over 20 micrograms is treated with an injectable as well as an oral collation drug. Much of the treatment has to do with presenting symptoms on admission. Once neurologic damage is done to a certain point, it’s irreversible.


“We are looking to work beyond when an eagle is released and track how it does long-term,” Craven said.

“We have an eagle that we helped rehabilitate. It came in and was impacted by lead. It was lethargic, it wasn’t feeding, and it had problems flying. After it was rehabilitated, it started to feed. By all intents and purposes, it looked like it had recovered.”

Craven’s team released the bird with a retrofitted backpack that monitored its movements.

“We started noticing that it wasn’t moving. It wasn’t flying from its perch tree. Subsequently we got a mortality signal from that backpack,” Craven said. “What we surmised is that though that eagle looked healthy and seemed to be rehabilitated, it was affected by lead poisoning such that it wasn’t able to cognitively hunt. It was able to feed in captivity, but its ability to hunt was impacted.”

The majestic eagle

For the LTBB, eagles are a revered animal.

“They are the highest-flying bird, they have great eyesight and to a certain degree, they are calculating,” Craven said.

“They plan on how to predate on certain species. We see them in the winter months looking on ducks as they migrate through. We know that they move around and are able to calculate and think where different prey will be.”

After ingesting lead, their cognitive power is limited, and more often they will scavenge instead of hunt.

Which only intensifies the problem.

The issue is nationwide

A national study that looked at 38 states concluded almost half of bald and golden eagles in the United States have lead poisoning.

Over a period of eight years, they gathered tissue from 1,210 bald eagles and golden eagles. Wildlife monitors who band birds with tracking transmitters and veterinarians rehabilitating sick or injured individuals sent feathers and blood to the team, and the researchers gathered liver and bone samples from dead eagles.

The team then measured lead levels, looking for acute exposure in blood, liver, and feathers and indications of chronic poisoning in bones. Nearly half of the birds showed signs of chronic lead poisoning — 46% of bald eagles and 47% of golden eagles.

Risk to humans

The Michigan Health Department recommends that children under 6 and pregnant women do not ingest venison if it has been shot with lead. These people have a lower threshold for handling lead in their systems.

Sporting Lead-Free is a non-political, educational initiative that does research on the topic. From 2020-22, the organization scanned more than 2,300 pounds of donated meat. Samples included animals like deer, elk, bison and pronghorn. They identified that more than 18% of packaged ground game meat contained at least one lead fragment.

Deer also have been known to eat small animals, and if that animal has lead in it, that affects the deer as well.

While an adult human has low risk from occasional small lead ingestion, no amount of lead is considered safe to consume.

Michigan becoming a lead-free state

“Our goal is to educate hunters and anglers to consider non-lead options. In my discussions with hunters, most of them don’t realize that it’s become such a problem with our eagle population in Michigan,” Manley said.

California is the only state in the nation that requires lead-free ammunition for hunting. The state implemented the law for a couple of reasons. One, they spent a lot of time rehabilitating condors, an endangered vulture. Lead-free ammunition helps sustain their protection. Two, California wanted to protect hunting families from lead as well.

In Michigan, LTBB is being proactive in the fight against lead.

“For us here at Little Traverse, we have implemented a lead exchange program for our tribal members,” Craven said. “So if they have lead ammunition, they can bring that in and we will give them non-lead ammunition.”

He added: “In order for this to take root here in Michigan, it’s just getting the information out and making these programs available on a larger scale.”

Lead-free options include solid-copper or copper alloys, available in a large variety of calibers and bullet weights.

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