I've had 2 girls that have crowed.
The one who has crowed the most, the rooster does not like. She's never been fertile. Maybe it threatens his masculinity.
The other one was a bantam who hatched out 2 chicks. At first I thought the little buggers were crowing at 3 weeks old. Nope. I saw mom crowing. I guess she was teaching them their language. Once she weaned them, I never heard her crow again.