I'm sure a lot has to do with the age of the capon, the age at which it was caponized, if there were any bits left behind during the operation, and the individual bird. Perhaps not all capons will crow, but I'm here to tell ya that some of them do. Furthermore, some won't crow but instead make a sound never before heard from any other chicken you've ever known, something like a shrieking yelp, sort of like the sound of nails being pulled from a board. It might make you wish they would crow instead. I want to share this information, because some folks think that caponization is the solution that will let them keep their roosters in yards where they shouldn't have crowing birds. I think it's just not a guarantee. I caponized these cockerels in order to make them more meaty when it's time for them to come in for dinner. They were about 8-10 weeks old when I did them, they're around 6 months old now. And just this morning I heard one of them giving a genuine crow, and another one sounding like some rare jungle bird.