by Monique Pettit, member of Water, Earth, Birds, and Bugs (W.E.B.B.) –
Anyone who has spent a weekend, a month, or a lifetime on North Haven knows the sense of awe in a serendipitous sighting of a bald eagle soaring above the island, or just resting on a tree branch. These magnificent raptors enrich our human experience.
But almost half of all bald eagles nationwide (the “lower 48”) are suffering from lead poisoning, according to a report released early last year.* Tissue samples from over 1200 golden and bald eagles, as well as blood samples from about 620 live eagles, showed harmful levels of lead in 46% of those tested. In high doses, this neurotoxin can cause seizures, respiratory problems, organ failure, brain damage, anemia and eventually death—but even low levels will undermine eagles’ balance and stamina, impairing their ability to fly, hunt, and reproduce. Leigh Hallet, the Executive Director of Avian Haven, a bird rescue and rehabilitation organization based in Freedom, Maine, stated that since November of 2022, six bald eagles were admitted to their facility with elevated lead levels, and four of those died.
Eagles aren’t the only victims. The American Bird Conservancy website states that, “an estimated 16 million birds are poisoned by lead every year. Some birds, like Bald Eagles, accidentally ingest lead shotgun pellets and ammunition fragments when scavenging on carcasses or remains left by hunters. Other birds such as Mourning Doves mistake spent shot for seed in fields and forests, while diving birds like Common Loons swallow lead fishing tackle while foraging on lake bottoms.” And in fact, in addition to the bald eagles treated in recent months, Avian Haven also admitted two loons with elevated lead levels. Fall and winter hunting seasons are particularly dangerous for eagles and other “scavengers.” Ingested bullet fragments are absorbed into the bloodstream, and gradually build up in bones and the liver. As little as 0.5 to 1 centimeter of lead (about the size of a grain of rice) is enough to poison a bald eagle; less than that will build up into chronic poisoning, ravaging the bird’s nervous system. And human health takes a toll as well. Lead bullet fragments or residues in game meat pose a significant risk to hunters and their families – particularly children – due to the ease of absorption into the bloodstream, and accumulation of even small amounts over time.
For eagles, the dangers from lead poisoning contrast with other successful conservation efforts for the species. After facing extinction in the 1960s, bald eagle populations rebounded with new bans on pesticides (particularly DDT in 1972), and protection of their habitat. As a result, they were removed from the federal endangered species list in 2007. The current plague of lead poisoning threatens that progress, likely stunting their rate of population growth by at least 4%. While that number may seem small, it undermines the overall resilience of eagle populations as they face other threats from climate change, disease, and collisions with wind turbines and power lines.
Researchers, conservationists, and wildlife managers hope that a voluntary switch by hunters to non-lead ammunition will make a difference, just as the ban on lead ammunition for waterfowl in 1991 reduced contamination of waterways. In California, lead bullets were banned in 2019, largely to protect the endangered California condor, and wildlife organizations now offer hunters free non-lead ammunition to make it easier for them to comply with the law. Hunters are also encouraged to switch to copper bullets – offering better performance and cost-effectiveness – and to bury all carcass remains that are contaminated with lead shot, since removal of all bullet fragments is nearly impossible. And hunters have suggested even more innovative solutions, such as “trade-in” programs that swap out lead shot for other less toxic options.
One problem is that there is a lack of knowledge about the profound impacts of lead on eagles, and about its insidious persistence across the environment. Basic education can help to catalyze these changes. Avian Haven’s Hallett states that “fortunately, there are now many hunters who are fully aware and act as advocates on this cause,” and they are part of a growing movement to ditch lead entirely. These changes ripple across the environment, not only protecting eagles and other birds, but also keeping lead out of precious groundwater which we use for our drinking water supply, and protecting all species – humans included! – from lead contamination in meats and associated products.
As scientist Rachel Carson described so poignantly in Silent Spring, toxins find their way across and through the whole ecosystem. Lead is one of those. But as with DDT and other poisons, we can change our course, with both voluntary actions, and well-informed regulatory decisions. Most people now agree that removing lead from gasoline was a good idea. We know how to do this when we understand the need to do so. And the results are so positive when we care enough to act. Let’s work together to make Maine lead-free!
For more information on this issue, and key steps you can take to help eagles, birds, and our planet, go to Cornell University Wildlife Health Lab publication, https://cwhl.vet.cornell.edu/article/what-you-leave-behind
* study cited above was conducted by U.S. Geological Survey, U.S. Fish and Wildlife, West Virginia University, the Virginia Department of Wildlife Resources, and Conservation Science Global.