Birds are an ecological litmus paper.

Vultures are homely, but they clean up all the garbage and that's good. And they're elegant in the sky.

Birds, it must be admitted, are the most exciting and most deserving of the vertebrates; they are perhaps the best entre into the study of natural history, and a very good wedge into conservation awareness.

Birds ... are sensitive indicators of the environment, a sort of "ecological litmus paper," ... The observation and recording of bird populations over time lead inevitably to environmental awareness and can signal impending changes.

The truth of the matter is, the birds could very well live without us, but many -- perhaps all -- of us would find life incomplete, indeed almost intolerable without the birds.