Challenge Certificates
At some of the larger shows Challenge Certificates (CCs) are awarded to the best budgerigar of each colour group. When a bird has won a specified number of CCs it can be registered as a Champion Bird, regardless of the status of its owner. The best budgerigar of each CC colour goes forward to compete for the Best in Show award.
See https://www.budgerigarsociety.com/types-of-patronage-available/