I had a hen that started a 3/4 crow at about 2 years. About the only sound she could make but rarely did was normal hen noises. She would bugle, squeal, whistle. But "bawk, bawk"?? None of that silly stuff though she did sing the egg song like a proper girl. She wasn't a morning crower, she (like any rooster) crowed whenever she felt like it during the day. It was just one of her repertoire of vocalizations.