I'm starting to have some severe behavioral issues with my flocks. It's totally my fault. It's being corrected but I would like some opinions. For reference all birds are large fowl except one silkie roo. I had an established flock of 2 SF Roos, six SF hens one polish hen and one silkie roo all 1 1/2 years old. We decided we wanted to try some different breeds adding some color to the flock and the egg and I acquired 4 APA Ameraucanas two Dan Powell GLBs and two OEs which are Ameraucana roo x Bev Davis BCM lines. They are six months old now. I also have a younger 5 month old flock of SFs. The mixed batch and the mature birds shared space at night and the baby SFs had a separate coop. All free range together during the day. After the recent incidents, I have switched the mixed flock and the babies around. It was all fun and games, no trouble at all. There WAS the one little mishap where the olive egger roo got into the baby coop and killed two young roosters. Unfortunate but we fixed the faulty latch and it was all good. Then my lap pet silkie became an ankle biter. Not the worst thing in the world, but weird. I gave away 3 of my mature SF hens and one of the SF Roosters (guy and his wife both out of work, really needed the eggs now so I let go of the mature birds). Now, all of a sudden my OE Roo and one of my Ameraucana Roos is gang banging my poor little polish hen. I mean that literally. I have had to hunt this hen every evening for a week because she was not coming in at night. I finally caught them, one would help hold her down for the other to mate with her and then they would switch. She was in a tangle of briars that I had to hack my way through so I got quite an eyeful while trying to get to her. Once done with their mating, they were intent on killing her. It was brutal and she was a bloody mess. I broke up the attempted murder and have the hen sequestered. The Roos showed no aggression toward me when I shoved them away. These guys bother no one except this hen and none else gives the hen any trouble. She shows no sign of illness (and I'm pretty good at spotting early illness in my birds as I know they tend to hide it) so I'm not sure why she has been singled out. Sure she's docile but not nearly as much as the SF hens. The Roos don't fight amongst themselves at all. I know that mating can get aggressive but I had no idea that two Roos would work together in this way. Their obvious intent was to kill this hen, not to mate. It was just a sadistic act and I have never seen birds behave that way. Today, my OE hen lost her mind and started attacking my brahma roo and my youngest birds. Beak open flat out chasing them down to fight. She was as vicious as the Roos were two days before. The rest are pretty normal except that no one is laying eggs which I totally understand now. So, what's up with the sadistic aggressive birds? I have separated the evil roosters from the flock and tomorrow will separate their heads from their bodies but I am curious if this behavior is common. My two SF Roos ruled together with gentle yet firm wings. They were a great team. Down to one, I get that the younger Roos are going to vie for position but like this? And is the younger hen aggressive now because three of the older hens have gone and why is she after the poor brahma boy? I really want the hen to calm her jets and be able to keep her so I'll keep an eye on her. I understand that as she matures she may shake up the pecking order a little but I don't understand her singling out the roosters to pick on. Is she is angry about being separated from the Charles Manson club? Can a hen be a groupie? Are there documented cases of demonic possession of chickens? As I said, I know how to fix this. My question is why?