This is BirdNode.

When a Carolina Renn tips back its head and sings, something remarkable happens.

A Carolina Renn can sing so loudly that he almost has to shout to be heard over its song.

Renns aren't the only small birds with big voices, but they are the best known for this

ability.

How can a bird like a Carolina Renn, all of five and a half inches long and weighing

only as much as four nickels, produce so much sound?

The answer lies in the songbird's vocal anatomy.

Unlike the human voice, which comes from the larynx way up at the top of the windpipe,

a bird's song comes from deep within its body.

Birds produce song in a structure called the serenx, located at the bottom of the windpipe,

where the bronchial tubes diverge to the lungs.

The serenx is surrounded by an air sac, and the combination works like a resonating chamber

to maintain or amplify sound.

Evolution has given birds a far more elaborate sound mechanism than its given humans.

Where we wound up with a flute, songbirds got bagpipes.

For Bird Note, I'm Michael Stein.

Support for Bird Note is provided by Jim and beer to Faulkner from Seattle, Washington,

and generous listeners around the world.