I have 8 barred rocks that are about 8 weeks old. I am nervous that several of them might be male. I cannot put my finger on what exactly seems male about them, perhaps their slight scary Velociraptor look Some seem to have a more upright posture, and they are fighting a bit. Their fighting includes puffed feathers and bumping chests. Is that a chicken behavior? At 8 weeks are there any characteristics I can look for to sex these chickens? Thanks so much in advance for your expertise.