Years ago I had some hatchery Reds that were very aggressive towards the other birds but not with people. There was one I thought she was going to kill some of the pullets that were in the same pen. She would get on them and peck them bloody. I would take her out of the pen and put her in a cage for a few days and then put her back in with the flock and she would go after the others again and I would take her out again. She would guard the pop door and not let others into the coop to eat so I put another feeder under cover in their run and cut a second pop door in the coop. She would still attack the others but that did help. One day I saw her beating up on a pullet. She was so intense she didn't know I was there. I had a hose in my hand and gave her a good squirt. She was so startled by the water that she jumped off the pullet and ran into the coop. She didn't come out for quite awhile. I did that several times. She finally gave up. It did finally break her but it wasn't easy.
