LETTER FROM THE AMAZON - Amazon Conservation Association

Letter from the Amazon January-March, 2010
The Raptors of CICRA
While working as a field assistant for Ursula Valdez
in 2004 and 2005, I noticed that the mining along
the river Madre de Dios had almost tripled over the
course of the year. Because the miners use
mercury to extract gold from the sediment, I began
to wonder about the presence of mercury in the
area, and particularly its effect upon the wildlife.
Because mercury bio-concentrates over the lifetime
of an individual, and bio-magnifies in the food web,
top predators like raptors are ideal for diagnosing
and monitoring mercury contamination in the
ecosystem. In August of 2006, along with my
collaborator Juan Carlos Galvez, I began a study to
measure and monitor mercury levels in the raptors
of Los Amigos.
Mercury is one of the most toxic substances on
earth. It is a teratogen (causes birth defects), a
mutagen (permanently changes genetic material), a
carcinogen (causes cancer), and a neurotoxin
(affects nerve tissue including the brain); it also
causes blood chemistry and cytochemical changes.
In birds, dietary mercury exposure can be directly
lethal, or can have sub-lethal adverse effects on
reproduction, growth and development, behavior,
metabolism, and blood and tissue chemistry.
In the field, we capture raptors using mist nets or
Bal-Chatri (BC) traps and take blood and feather
samples for mercury analysis. Feather sampling is
an easy, non-invasive method of determining
mercury levels because mercury is deposited in
feathers as they grow. The concentration of
mercury within the feather has a direct correlation
with the individual’s mercury level. Samples are
later analyzed at Clemson University.
Roadside hawk (Buteo magnirostris); Margaret Shrum.
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