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. You can report the sighting to the Bird Banding Laboratory, a part of the U.S. Geological Survey that studies banded birds across the continent. Analyzing where and when banded birds are seen helps biologists figure out bird lifespans, migratory routes, and how their populations are changing.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.