Wild Life Considerations: N.E. loons facing new threat
By Robert Braile
Boston Globe Correspondent
The loons that grace northern New England's lakes and rivers are cherished birds, the inspiration for everything from festivals in their honor, to compact discs of their distinctive wail, to wood carvings of their elegant black and white form. But toxic methylmercury is taking a toll on the loons, undercutting their ability to reproduce and survive, according to the findings of a team of private, government, industry, and academic researchers.
Many loons are producing only half their normal number of offspring, they found, in part because their eggs have become more fragile. The contaminant in their blood, a form of mercury, exists naturally in the environment, but it is turning up in high levels across New England, mostly because of air pollution, especially from incinerators and coal-burning plants.
''There's a lot of evidence to suggest that New England's loons are in trouble,'' said David Evers, director of the BioDiversity Research Institute, a Maine nonprofit group on the team. After seven years of research, the team has shown for the first time that loons are being damaged by methylmercury.
The most threatened loons are in Maine, where most of the pollution sweeping into New England from the South and West ends up. There, 27 percent of the loons contain so much methylmercury that it is disrupting the formation of their eggs, as well as the birds' behavior, development, immunity, and long-term survival. The picture is not much better in New Hampshire, where loons soared to fame in ''On Golden Pond,'' the 1981 movie starring Katherine Hepburn and Henry Fonda that was filmed on Squam Lake. In that state, 15 percent of the loons are threatened by mercury. The figure is the same in Vermont and 10 percent in New York.
New England's loons have long been known to have the highest methylmercury levels in the country, at least four times those of the same birds in relatively pristine Alaska, which are considered baseline. Methylmercury is so pervasive and severe that every state in the region has advised anglers in recent years to avoid eating much freshwater fish, the loons' top food source, because the fish are laced with the contaminant.
But loons are not the only creatures that consume fish, and the researchers say it is now time to take a closer look at how methylmercury may be harming wildlife such as bald eagles, great blue herons, otters, and minks. All may be facing the same threat as loons, an ''indicator species'' whose health reflects the overall ecological health of the landscape on which it lives.
''Any of the wildlife that depends on fish for its diet will be similarly affected,'' said Drew Major, a biologist at the US Fish and Wildlife Service. It is also on the loon research team, along with the US Environmental Protection Agency, state fish and game and environmental agencies, private conservation groups, Tufts University School of Veterinary Medicine, Canadian Wildlife Service, and SPL Energy Maine Hydro.
The team, known as the Northeast Loon Study Work Group, also found that the loons at risk are behaving in ways that harm their young: spending less time nest-sitting, foraging, resting, and preening than healthy birds, while rustling about more for no productive reasons, wasting needed energy. As their blood-mercury levels rise, the birds are producing lighter eggs that are less likely to survive, and are growing asymmetrical flight feathers, making it harder to fly, and thus compete and survive.
They are also producing more corticosterone, a hormone associated with stress. ''When you see a report like this, you realize that more has to be done faster,'' said Kate Hartnett, senior biologist with the Loon Preservation Committee, an arm of the Audubon Society of New Hampshire and another team member. ''This should serve as a wake up call to get going.''
Efforts are underway in the region to slash mercury emissions from incinerators, power plants, manufacturing plants, and other sources. The states are at various stages of meeting a 1998 pledge by the New England governors and Eastern Canadian premiers to halve emissions by 2003. Some on Capitol Hill, including Sen. Patrick Leahy, Democrat of Vermont, are pushing for stronger federal controls following the release last year of a long overdue EPA report to Congress.
''Loons have been like coal mine canaries as we have studied the environmental effects of mercury,'' Leahy said, commenting yesterday on the report. ''They are among the first animals to show its poisonous effects on organisms and ecosystems as it accumulates on its way up the food chain. Mercury is the last major toxic without a control strategy because the corporate polluters have prevented action by arguing that we need more evidence.''