I don't have that many birds to keep track of so it's not hard. The most clutches I've ever had in a single year was 4 (18 chicks total), and it's usually just 2 clutches a year with 8 to 10 chicks. I do keep some simple written records showing the parents, date egg was laid, date of hatch, sex and mutation of the baby, etc. My total to date is 10 clutches and 46 chicks, so I would have completely lost track by this time if I didn't keep some kind of record.
Bigger breeders often keep more extensive records, especially if they're show breeders who need to keep track of the pedigrees for several generations. Susanne (srtiels) has some forms on her website at
http://www.justcockatiels.net/free-stuff.html that people can use, and other websites also have samples of breeding record forms.
