When do roos change tones?

[mtcookie]

I currently have a 15 week old cochin roo that still chirps. When should I expect this voice to drop?

My girls had changed by this time.

 

[RonB]

MY 18 week old BR rooster crowed for the first time today! twice at about 11:am and then twice at about 5:00pm. He sounded like a pro!!!!

 

[australorp_breeder]

Most of the roosters I've raised in the past started crowing around 6 or 7 months when my hens started laying. I'd love to see a picture of him! I just bought a Partridge Cochin cockerel from someone at the County Fair and he's 8 months and crows. So definately by 8 months your Blue Cochin should be crowing.