We have 24 Plymouth Barred Rocks that we hatched via an incubator that are now 13 weeks old, and doing great free-ranging and sleeping in the barn with our year-old hens (their moms). Out of the 24, we have nine pullets and 15 cockerels, and the boys have all started their normal rooster behavior (including crowing) in the past few weeks. Except for one cockerel, who opens his mouth to crow, and does the whole neck-stretching thing, but no sound comes out. He's quite large and healthy looking in every other way, but appears to be completely silent. Is it possible that he is somehow completely mute? He'll go through the motions numerous times a day, but there's just nothing coming out. Just curious!