Canary in a Coal Mine

Common birds are disappearing:

Some of the most common birds seen and heard in American back yards are becoming a less frequent sight and sound in much of the United States, according to a study released by the National Audubon Society.

Twenty common birds -- including the northern bobwhite, the field sparrow and the boreal chickadee -- have lost more than half their populations in the past 40 years, according to the society's research.

"These populations are not yet on the endangered species list, but it is noteworthy, and we need to take steps to protect their habitat," said Carol Browner, Audubon chair and former Environmental Protection Agency administrator.

And like the proverbial canary in the coal mine, the health of a region's bird population is often a harbinger of the health of other wildlife and of human populations as well.

"The focus isn't really on what's happening to these 20 birds, but what's happening to their environment," said Greg Butcher, the society's conservation director.

Global warming and increasing corn production to feed the ethanol boondoggle are contributing to the loss of birds.