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While bald eagle populations are clearly healthier now then they were in the 1960s, Domenech and wildlife biologists are seeing a steady decline in the number of golden eagles migrating through Montana en route to northern nesting grounds. There's no proof the population is waning; the birds may be simply changing their behavior. Or there could be a darker cause. "Exact causes of the decline, that's up for debate," Domenech says. "Could lead be contributing to that? I would say it certainly could possibly be contributing to that."
How bad is a little lead?
Lynn Vaught is worried about a golden eagle she took in several weeks ago. It was found lying on a deer carcass near Whitefish Lake. Though right on top of a ready-made meal, the animal was too weak to feed.
"His lead levels were the highest I've ever seen," says Vaught, who through her nonprofit, Wildlife Return, rehabilitates everything from songbirds to mammals.
Vaught typically treats one or two birds with acute lead poisoning per year. The Center for Biological Diversity estimates that more than 10 million birds and other animals die in the United States annually from lead poisoning. Rehabbers treat the toxicity with chelation therapy, using a chemical that binds with lead. It helps the body flush the metal out.
Vaught's golden eagle responded well to treatment, but just as the bird appeared to be recuperating, all of its feathers fell out. Vaught, a 35-year-rehabbing veteran, believes lead poisoning from eating contaminated gut piles caused what she calls the "traumatic molt."
Because of the impacts of lead on wildlife, scientists are working to identify whether lead-harvested game meat could make people sick, too. Based on concerns about the metal's effect on humans, the CDC in 2008 conducted a study to gauge lead levels among people in North Dakota that ate lead-harvested game.
The CDC tested blood from 736 people in six North Dakota cities, evaluating how much lead-harvested wild game study participants ate and whether those tested could have been exposed to the metal through other means, via, for instance, occupational hazards, hobbies, or in the home. The CDC found that people who reported eating lead-shot game meat averaged lead levels of 1.27 microgram per deciliter, significantly higher than the 0.84 microgram-per-deciliter average among those who ate no lead-shot game.
Scientists know that lead affects people, specifically children, at levels lower than the CDC's 10 micrograms per deciliter threshold of concern, says Dr. Shahed Iqbal, the lead researcher on the North Dakota study. He cites studies that show cognitive changes in kids with lead levels in the 2 microgram-per-deciliter range. "There is no safe level of lead in the human body."
Still, Iqbal says it's too early to discern if game meat poses a threat to people. The CDC's North Dakota study did not examine health effects. "What we have identified from this study," he says, "is the consumption of wild game can serve as an added source (of lead). How it operates is a different question."
Based on concerns about lead poisoning in birds, the federal Fish and Wildlife Service in 1991 banned lead ammo in waterfowl hunting. In 2008, California prohibited lead ammunition use in areas of the state inhabited by the California condor, a federally recognized endangered species that, like the eagle, suffered a significant population loss from DDT. In Montana, FWP administrators proposed limiting lead shot in wildlife management areas statewide, but opposition from hunters put the kibosh on the idea, says FWP spokeswoman Vivica Crowser. "Overwhelmingly, (public comment) was not supportive of making that change." In 2010, the FWP commission, by a 3-2 vote, nixed a proposal to limit the use of lead shot on certain state-owned lands.
Similarly, acting National Park Service Director Dan Wenk in 2009 proposed phasing out lead fishing tackle and ammunition in national parks by the end of 2010. Wenk said in a release dated March 10, 2009, "The reduction and eventual removal of lead on Park Service lands will benefit humans, wildlife, and ecosystems inside and outside park boundaries and continue our legacy of resource stewardship."
Gun rights advocates argued the Park Service gave them no notice and mobilized quickly. Eight days after Wenk made his "Get the Lead Out" announcement, the agency backpedaled. "In the future, we will look at the potential for transitioning to non-lead ammunition and non-lead fishing tackle for recreational use by working with our policy office and appropriate stakeholders/groups," the Park Service said.
The debate is far from over. The EPA last year denied a petition submitted by the Center for Biological Diversity that sought to "ban the manufacture, processing and distribution in commerce of lead shot, bullets, and fishing sinkers." The agency said that Congress has not authorized it to regulate lead ammunition. Undeterred, the Center for Biological Diversity, Public Employees for Environmental Responsibility and a group of hunters that call themselves "Project Gutpile" sued the EPA in November 2010. They're asking a U.S. District Court judge to overrule the EPA's decision.
Sen. Tester's bill aims to end this legal wrangling by permanently exempting lead ammunition from federal regulation. Tester's camp says passing the bill is necessary to protect hunters, recreationalists and gun owners. "Even the EPA agrees it doesn't have the authority to ban lead in hunting ammo and fishing tackle," says Tester spokesman Aaron Murphy. "Rather than use the courts as a bully pulpit and sticking taxpayers with the bill, Jon believes in using a common sense approach that balances healthy wildlife with our outdoor traditions."