Metals in Moose and How Hunters Can Help Eagles

Female moose feeding on grass. Photo by Michelle McAfee

April 24, 2025

Anna Somers - CRR Staff

On March 21, WISE hosted a “double header” of lectures as part of its 2025 Science Lecture Series at the Wrangell St Elias National Park Visitor Center in Copper Center. Kelsey Stanbro from Ahtna Intertribal Resource Commission (AITRC) spoke about toxicology research in moose populations in Ahtna region, and Travis Booms from the Alaska Department of Fish and Game (ADF&G) discussed the connection between lead ammunition and poisoning in Alaska’s hunter and wildlife biologist who has spent years evaluating the impact of lead bullets on the Alaska ecosystem. He has worked for 16 years for ADF&G, based in Fairbanks. Booms has found lead bullets are likely the culprit of lead poisoning seen in eagles across the state.

Booms is a co-author of a paper first published by the journal Science in 2022, which showed that across the entire United States, nearly half (46%-47%) of bald and golden eagles show signs of lead poisoning. In Alaska, Booms focuses his attention on lead poisoning in golden eagles, testing the levels of lead in the blood of animals from Nome all the way to Gunsight Mountain. In raptors, as well as many other mammals, too much lead in the blood can cause seizures and other neurological problems, organ damage or failure, lowered immune response, reproductive issues, and more.

According to Booms’ Alaska-based research, 16% of golden eagles in the state showed blood lead levels that indicate lead poisoning. Lead can be introduced into an ecosystem in a variety of ways. For example, if a house burns down that had lead in its paint, some of that lead is released into the environment. However, Booms believes that lead bullets are the primary culprit for the high lead levels in eagles, citing a research study that showed significantly higher amounts of lead in eagles during and just after hunting season.

One reason that lead bullets can result in lead poisoning in eagles, according to Booms, is that when a moose or a caribou is shot with a lead bullet, the lead fragments and disperses, with up to 40% of the bullet’s weight left behind in the animal.

According to Booms, 20 mg of lead (about the weight of a grain of rice) is enough to kill a bald eagle. For this reason, Booms is in favor of copper bullets, which retain 99% of their weight instead of fragmenting and do not cause the same health impact on animals as lead poisoning.

In 2024, as part of a partnership with the Alaska Falconers Association and the Alaska Backcountry Hunters & Anglers, the Alaska Copper Ammo Challenge was launched. A hunter with a valid hunting license and Alaska mailing address can turn in receipts for two boxes of copper bullets in exchange for $80 in gift cards. This is part of a statewide initiative to encourage hunters to switch to copper bullets, which Booms states have higher penetrative power than their lead counterparts and are therefore more effective for hunting apart from their safer impact on the ecosystem.

To date, over 600 boxes of copper bullets and gift cards have been claimed. You can learn more about the Alaska Copper Ammo Challenge at akcopperchallenge.com. Kelsey Stanbro is a Glennallen-based ecologist at AITRC whose work includes studying toxicology in Alaska wildlife.

Stanbro is conducting a moose health project, which measures copper and cadmium levels in moose harvested in the Ahtna region. Stanbro’s team requests small Ziploc bags from hunted or roadkill moose that contain a small sample from the moose’s kidney and liver, as well as two teeth and some hair with roots attached.

These samples are assessed for nutrient levels, and Stanbro specifically looks to see if there are risks of cadmium poisoning or copper deficiency in our region’s moose populations. Some older moose show signs of higher cadmium levels, and 27% of moose tested had copper levels below the ideal threshold, but Stanbro and her team plan to engage in more research to fully understand their results.

Both of Friday night’s lectures shared valuable insights about how human activity can impact the ecosystem and how important it is to ensure good health for the animals we depend on for sustenance.

Disclosure: WISE is a CRR advertiser. This does not impact our coverage of their events.