Most bands are made of an aluminum alloy. The numbers are stamped into the band and can wear off with time. The average band on a Mallard wears one number off in 8-10 years. A band on a Redhead is often worn completely (no numbers legible) in this same 8-10 years. Band wear depends greatly on the amount of time a bird spends in the water, particularly salt water.
If you find a bird band with one or more numbers worn off (or if the band number
is struck with shot) mail it to the Bird Banding Laboratory to be etched. The
number can be retrieved successfully in most cases. Bands are etched using an
acid solution. Where the number was stamped on the band is weaker
and the acid solution lightly erodes away more metal where there were numbers,
so the actual number is seen when the band is rinsed. The band will be returned
to you when the number has been determined.
To send a band to the Bird Banding Laboratory, flatten the band, tape it between two pieces of cardboard, wrap the band in padding, or place it in a small box if you want to keep it round. This is very important, as otherwise the band may cut the envelope and be lost in the postal system. Also write on the envelope HAND CANCEL. Send the band with all the information on how, when, and where you found the band with your address and email address to: Bird Banding Laboratory, Attention: Band to Be Etched, 12100 Beech Forest Lane, Laurel MD 20708. The band will be mailed back to you whether we are successful in retrieving a number or not.
Please be sure to include your email address with the band to allow us to email your Certificate of Appreciation that will include the original banding details.