I am pretty new to the chicken thing and sofar rooster have been eaten once making noise and never had a capon BUT I wonder if the crowing thing is sort of like with dogs, if you get them neutered before they begin leg lifting they often don't start leg lifting, but if you neuter them later and the behavior has begun memory can make it continue rather than hormones.
Do capons crow? - Page 3
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I know it's been a long time since this thread has started but just as an FYI some capons will eventually start crowing. I've read that they don't depending on how early you caponize them but I did mine roughly between 5-8 weeks and one of them just started to crow at 8 months. The others never made it this far... The slips continued to grow as if they were in tact so they crowed around 4 or 5 months and is now in freezer camp for rehabilitation. I haven't tried to see if they will crow if there are no other roosters in the area. Roosters crow to show dominance and let other roosters know whose territory it is along with attracting other females in the area. I believe if other roos are crowing nearby they have a higher tendency do it also. I hope this helps.