I just moved 5 4 week old chicks into their coop, with a light in the corner for warmth, where it stays mid 80's. The coop is 4x6, bigger than the box they were in, with ladders to roost on and lots of room. All of a sudden they are viciously attacking the only obvious roo in the group, although there may be more roos. They're not just pecking, they're attacking to kill it seems! He had the most obvious pink comb, which is now bleeding, and he's so scared he won't come down from up on the highest roost, where it's going to be too cold! He isn't allowed under the light! He's a very healthy and active guy, not weak or sick so I don't get it. At the moment he's in my house but I know he has to go back - what do I do? These chicks are EE/bantam mixes, all different, starting to show some size difference. He was the biggest but 2 are now a bit bigger. HELP!