I am starting to use leg bands only because I think I can remember the date they were born only to forget about 6 months later. Leg bands are great ex a green leg band could mean a 1 year old chicken a red one might mean a 2 year old ect
which offer a numbering system. This is what i was looking at cause later i can document details from how early i could see movement, to what my prediction in candling was to bloodline of the chicken (so i dont inbreed) and anything up to and including if she whooped the chiuaha in the yard on may 27th and made the kids giggle. I know its overkill but im very scientific so i like to keep logs of complications, suprises, egg production, etc.