The reasons for not banding vary, while the reasons to band remain the same. Reasons for Banding Closed bands placed on a chick while it is still in the nest are the only sure-fire ways to identify a bird. The window for banding a chick is usually open for a few days, a week at the most. Once the bird is an adult, it is nearly impossible to remove or add a closed band without cutting the band itself. The band remains as a permanent marker that the bird was bred domestically, and the band numbers are used to trace show points, or simply as an identification device.
Bands make it easier for the chick to be traced back to the breeder.
Many societies that offer bands also offer services to trace them back to the person to whom the band was issued. If someone purchases a bird with a traceable band, then if the person would like more birds from the same breeder, the person can have the band traced through the society from which it was issued. People who purchase bands on their own usually place their initials on the band, and while this isn't as easy to track, it still is traceable back to the person with those initials through contacts within the avian world. Bands may be the only way to tell the age of a bird. Birds do not visibly age for many years once they reach maturity.