Most bands have the year, a code for the aviary where the bird was hatched,sometimes state intials, and usually a number which only the breeder uses to keep records on the individual bird.
for example my bands have KPPA for my aviary followed by NYS, the state and then numbers so i can keep track of whose related as well as records on the baby such as weight.
another example my suns band number is MBF NYS 18...breeder, state, bird number..
although imports have round bands that usually just have numbers on them which i believe are only a number given to track them after theyve come into the country.. only while they are in quarantine then its just a sign that they are in the country legally..
alsoits okay to say the birds number unless it's lost/stolen then people could take the number and say its their bird if say you publically announced it in fliers or such where everyone could see, then someone posts a found flier and asks for that identifyng info to re-claim.. hope that made sense!
hope i could help!
