I think the OP means an adult rooster who does not crow, so if one is just five months, that wouldn't necessarily be considered a non-crower, just a late crower. If the rooster is under a year old, he still has time to crow. My show type Barred Rock cockerel, Rex, did not crow until he was 6 months old, the latest I've ever had. I've also had one crow at just 4 DAYS old in the brooder. It would be one in a million rooster who just never starts to crow, even as an adult male, mating the hens and doing all other general rooster duties. We can always dream, I guess, though personally, I like my roosters' crowing, even at 3 a.m.