I have 25 12 week old EE in coop 2. We are trying to build the run, but a week off from really finishing it. It is hot, have fan, etc. They are in 12x12 area. Tonight noted one of my girls had only one tail feather. I look and her back side is bloodied, but not bad. I separated her into dog crate and have one end of it safely butted up so she can still see and be seen while she heals. I saw one of the culprits, my question is, is the culprit in need of separation too? Just in case I put an extra brooder with lid in the coop so i can quickly separate the picker or another that has been picked. I will take measure to give them more to do tomorrow. I have tried to free range 12 wk olds with my other group but this group is a bunch of well, . . . Chickens. They run back into coop with or without the other group (16 weeks) outside free ranging. So, is it likely one culprit? or once it got started, a free for all and I just happened to see one trying to get her fair share of the bloodied tail? Anyone with experience, please chime in, I know fault lies with them needing more space, but has never happened until tonight, so we are working ASAP to fix this but it takes time and money and I am working on it. Thanks in advance, my flock thanks you too. Poor little girl is ver flighty but as soon as I cuddled her, she relaxed and closed her eyes. Such a sweety. Also her injuries do not seem nearly as severe as some I have seen here, so I think she will be ok.