I know this is a hot topic by many. I have searched thru the threads but really didn't find a definitive answer to my situation. I have three layers, Barred Rock, Iza Brown and an Easter. These three are my first ones and now are 1y 4m old. I recently picked up two more this year, Buff Orpington and a Black Laced Wyandotte. My Easter is at the top of the order and my Iza at the bottom. Both my Iza and Barred have bare bottoms, no blood, from the Easter pecking at them. I have been trying to introduce the new girls, which are now 15 weeks, for about a month. When it was warm enough to set the them outside, I put them in a brooder within the pen. I also have a tractor which I have setup outside of the pen. I have been rotating the two groups, in the tractor and pen, so they all get equal amounts of time for dust baths and foraging, trying to get them acquainted with each other without the physical drama. Moving FWD I did have them all in the tractor and in the pen multiple times, while monitoring, to see how the transition went. My Barred pecked at them somewhat but my Easter and Iza just go insane and gang up on the new addition without remorse. I am at a point now where I can leave my Barred housed with the new ones with no issues but the issue still persists with the Easter and Iza. My setup is this ... a 4'x7' pen attached to a shed. Within the shed are their nest boxes, food and water. For the 5 hens I would imagine this is enough space, including the tractor? At night i rotate them between the coop and the pen but now leaving my Barred with the new girls, isoalting the bullies. I don't what to do with the other two. When they start hammering the new girls, my Barred will follow suit sometimes which is frustrating.