I have a Barred Rock and an Ameraucana that I got from the feed store that are both 13 weeks old (the 3rd one, a Rhode Island Red, all of a sudden had seizures then dropped dead at 8 weeks). We bought them at 4 weeks and all 3 were supposed to be pullets. The RIR was clearly a pullet. I mention her because she was only half the size of the other two when she passed (all the same age), which could be an indication the much larger ones are cockerels. But based on looks alone, the Ameraucana clearly looks to be a pullet to me. I'm just not sure about the Barred Rock. I think we might have one boy and one girl. But recently they started sparring against each other very aggressively with their neck feathers flared. This was strange behavior to me because I did not think cockerels and pullets would fight each other. I have heard of boys fighting boys and girls fighting girls, but I have not heard about boys fighting girls. I would think that the pullet would immediately back down against the cockerel. If boys and girls do not fight each other, then that probably means we either have 2 pullets or 2 cockerels, but not one of each.