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Using Bald Eagles as Contaminant Monitors
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Learn More about Mercury• Mercury Falling Help us protect New York's Forests! Donate online now, or contact The Nature Conservancy office nearest you. Contact:
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What is being done to study the threat of mercury?
Last summer, The Nature Conservancy joined forces with the BioDiversity Research Institute (BRI) to evaluate the levels of mercury in the bloodstreams of songbirds found in the Catskills region of New York. Their results were alarming; research and analysis found high levels of mercury in several species of migratory songbirds, including the already-threatened wood thrush. The findings also raised concerns about how mercury could be affecting other high-risk species like bald eagles.
To investigate this threat, The Nature Conservancy and the BRI are partnering with the New York State Department of Environmental Conservation (NYSDEC) to expand the sampling to include eagles and fish species in the Catskills and Adirondacks. NYSDEC has the most intensive eagle monitoring programs worldwide, and has been documenting mercury levels in fish from lakes throughout New York for years. In addition, The Nature Conservancy will continue its long-term monitoring of surface and groundwater mercury, soil and sediment profiles, and invertebrate and fish sampling, all in an attempt to explore the connections between emissions that occur in the Midwest and human and ecological contamination in the Northeast.
How is the bald eagle sampling taking place?
This summer, scientists from The Nature Conservancy, BRI, and Peter Nye from NYSDEC traded in the gossamer mist-nets used to capture small-bodied song birds for the sturdy tree-climbing and protective gear necessary to reach the forest canopy and handle the sharp claws of nesting bald eagles. To obtain blood samples, trained climbers used boot hooks, ropes, and safety equipment to scale trees where eaglets between four and seven weeks of age had been confirmed present. When disturbed, the adult eagles will often circle overhead and vocalize, but will not aggressively defend their nest or attack the climbers.
Once in the nest, the scientists clipped a few feathers from the birds' breast for mercury analysis and banded their ankles. All eagles in New York are banded on one leg with a piece of blue aluminum carrying a unique letter-number combination and on the other with a standard U.S. Fish and Wildlife Service band. A small number of birds were removed from the nest for more in depth testing. When lowered to the ground, the eaglets were weighed and measured and a small blood sample was taken to test for contaminants as well as perform genetic analysis. When testing was complete, the chicks were hoisted back up to the nest. The entire process took about an hour per nest.
Sampling and banding efforts were immensely successful during the 2006 season, but samples have not yet been analyzed for contaminants. As in previous years, biologists visited roughly all of the active nests in the entire state, and samples collected on those visits will be analyzed for mercury.
For more information on eagles in New York, download the New York State Bald Eagle Report 2005 (.pdf, 517 kb) from the New York State DEC.
How Can I Help?
Help us protect New York's Forests! Donate online now, or contact The Nature Conservancy office nearest you.
