This is bird note.

If you see a wild bird with a small metal band around its leg, that means researchers

have given the bird a unique ID to keep track of it over the course of its life.

Only bird banders with a permit are allowed to catch and band birds.

Each species gets a band that's just the right size for its legs, from tiny hummingbirds

to massive swans.

If you see a banded bird, you can try and read off the serial code on the band with binoculars

or a zoom lens.

Then you can report the sighting to the bird banding laboratory, a part of the US geological

survey that studies banded birds across the continent.

The lab has amassed tens of millions of banding records over the years, analyzing where

and when banded birds are seen helps biologists figure out bird lifespans, migratory roots,

and how their populations are changing.

And that, in turn, can improve conservation efforts.

Banding records helped raise the alarm about declines in bald eagle populations due to

the pesticide DDT.

To learn more about bird banding, visit birdnote.org.

I'm Michael Stein.

Support for bird note is provided by the Bobbling Foundation and generous listeners around the world.