Sounding an Alarm on Birds and Mercury It was in 2005 that I first accompanied David Evers into the cool dampness of a Catskills forest. At the time, Dr. Evers, a biologist and director of the Biodiversity Research Institute in Gorham, Me., was hunting for some pretty small game. He had draped a net between several trees in a section of the forest in upstate New York and, with the help of a portable cassette player that replicated the sound of songbirds trilling merrily away, was luring tiny wood thrushes into the trap. It was a benign trap, part of a scientific study. Once he gently disentangled a bird from the net, Dr. Evers would stretch out its wing and count down to the 11th flight feather. With a quick tug, he would remove the feather and save it for analysis along with a sampling of the thrush's blood. What he was looking for was mercury. Back then Dr. Evers and other biologists already knew that mercury contamination in lakes and rivers had caused the neurotoxins to accumulate in the bodies of fish. Water birds like common loons that feed primarily on freshwater fish had also been contaminated; the toxin attacked the nervous system, making them act strangely. Among other signs, Dr. Evers noticed that the contaminated birds had trouble sitting on their eggs long enough for them to hatch. They seemed easily distracted, and the impact on the rates of reproduction was alarming. As he pursued his ecological sleuthing, he found that the mercury, which drifts into the Northeast largely from coal-burning power plants in the Midwest, was also being deposited on dry land, and that songbirds that survive solely on insects were also taking in dangerous amounts of mercury. As I write in Tuesday's Times, in the 11 years since he first started looking into mercury contamination, Dr. Evers has examined more than 6,500 blood samples from birds in 11 states. The bottom line, he says, is that the more he looks for mercury, the more he finds it. In a new study titled "Hidden Risk," he and his colleagues detail discoveries of mercury in habitats that were once thought to be safe, including beaver bogs, salt marshes and mountain forests far from power plants. For the first time he also sampled little brown bats, the ones that already are under so much pressure from white-nose syndrome, and found alarming levels of mercury. "We're finding out that many more species are in harm's way from mercury than we thought," Dr. Evers said. That follows what they're finding with human health. We keep ratcheting down to smaller exposures in people and finding more impacts. There's a parallel here. We're not working in isolation. Dr. Evers is not alone is finding troubling parallels between mercury contamination in birds and harmful effects in humans. Joanna Burger, a behavioral ecologist at Rutgers University who has studied mercury contamination in terns, skimmers and other shore birds, said those species were like canaries in a coal mine, showing us how dangerous the pollutants could be for people. Both she and Dr. Evers are encouraged by the new standards that the Environmental Protection Agency introduced last month to sharply reduce mercury emissions from power plants. But their long experience with mercury in nature has led both Dr. Burger and Dr. Evers to believe that the new standards, while important, are not sufficient in themselves to control the problem. Dr. Evers said that to determine how much of an impact the regulations would have, a national mercury monitoring network should be established. Legislation to create one has already been introduced in Congress (S. 1183 in the Senate and H.R. 3391 in the House) but with Congress at loggerheads over so many other issues, there is no expectation that passage will be either quick or easy. Because mercury pollution is a global problem, Dr. Evers and Dr. Burger also support the multinational effort to establish a global mercury treaty. Since 2009, the governing council of the United Nations Environment Program has been working to get a consensus among the countries of the world to decrease the rate of mercury pollution in the atmosphere. Dr. Evers said that 170 countries had already agreed to support the treaty, and the United Nations hopes to have it ratified before the end of next year. With the Chinese building a new coal-fired power plant every week, some in the electrical generating industry here in the United States have argued that the expensive new rules on domestic power plants will not accomplish anything. Dr. Burger disagrees. "We're putting more mercury into the air, and the situation is going to get worse unless we do something," he said. It may take weeks, months or years before we start to see any effects but we have to try to control things that we can control.