Pigeons Measure Pollution..

Studies conducted on pigeons in Jaipur city show that theses
birds can be used to measure city pollution, says researchers
at the University of Rajasthan, in northern India.

" Heavy metals present in the environment of the habitat
enter the feathers, and remain even after [the feathers]
are shed," explains New Delhi's Gobar Times, a supplement
to Down to Earth magazine.

Since pigeons normally live in a fixed area, the levels of
cadmium, chromium, copper, and lead detected in their feathers
may be an accurate indicator of local pollution..