Courtesy of Paul Baicich and The Swarovski Birding Community E-Bulletin:MERCURY, COAL, AND BIRDS
It all started with loons. Loon numbers in many locations have been
slipping. The causes have included water pollution, noisy boats, and
lakeshore development. But there is also the issue of fish and crayfish
(primary prey for loons) containing high mercury levels. And where does
this mercury come from?
Quite simply, the mercury comes from power plants and incinerators around
the country, and then is deposited in rain. For years we have known that
mercury emitted from coal-fired power plants, industrial boilers,
incinerators, and chlorine manufacturing plants falls into lakes and ponds,
where the mercury is then easily converted into a toxic form that interacts
with bacteria in freshwater sediment.
While the sources of mercury emissions in places such as in the Northeast
have declined 40 percent since 1990, coal-burning sources are still the
largest single contributor of airborne mercury. The upshot is that New
England now has a number of mercury "hotspots" where high mercury levels
threaten fish and wildlife. Studies have indicated that Common Loons in the
states of Maine and New Hampshire, for example, appear to be raising fewer
young than they need to keep the loon population stable. Besides loons,
other fish-eating birds - like bald eagle, osprey, and belted kingfisher -
can also have high mercury levels.
Researchers such as David C. Evers of the BioDiversity Research Institute,
however, have painted a much broader picture. In a study released earlier
this year, Evers and others have discovered that birds that do not eat
fish, such as forest songbirds and coastal sparrows, have also been found
to have elevated mercury levels in their bodies.
Indeed, the forest songbird species with the highest level of mercury
concentrations in its blood was the Bicknell's thrush
, a high-elevation
mountain species that might be considered among the farthest in distance
(altitude) from the lakeside habitat of the common loon. Apparently when
mercury-laden rain reaches mountaintops and moist forest floors, tiny
insects take up the mercury, and the mercury is then passed along through
the food chain, in this case to the Bicknell's thrush.
Until now, these terrestrial systems have been completely overlooked. While
the nine states in the Northeast examined in this study have or are
attempting to put mercury controls in place, there are still over 100 new
coal-fired power plants proposed in the U.S.
And as in the case of ethanol and other alternative energy sources, you
have to use energy to extract energy! Clearly everyone needs to become more
aware of what happens when we turn on the lights.
For a copy of the informative BioDiversity Research Institute report on
mercury, see this link