You bagged a banded duck; now what?
Q. I shot a mallard recently that had an aluminum band around its leg. How do I report it?
A. To report the band, call toll-free to 1-800-327-2263 (BAND) or report online. You can keep the band, as most duck hunters want to do. The U.S. Geological Survey will send you a certificate that tells you when and where the bird was banded, if you give a mailing address.
Any species of waterfowl or other kinds of birds can be reported at the same site. You can also report colored plastic bands, such as numbered neck bands on snow geese and swans, and wing tags on white pelicans.
Biologists have been banding migratory birds for decades, to gather valuable information about migration. Banding also provides clues about waterfowl harvest levels, and the data are used to set waterfowl hunting seasons nationally.
--Idaho Fish and Game