Until today, I had 2 runs side by side and separated with only chicken wire. One with 2 hens and a roo and the other with 1 hen and a roo. I had to give the roosters away today because I can not have them in the city. I was hoping to just move the one hen over with the other 2 since they are all bantam, and then add some larger hens to the other side. When I added the single hen to the other 2, the least dominant hen started attacking her. I left them alone for about 5 minutes, but ended up moving her back to the other side. It seemed to be very violent, pecking at each others eyes. The new hen actually had a peck mark about a centimeter from her eye. Not sure how to go about this or how long to let them fight it out. I do not want to see either of them loose an eye. They have been side by side looking at each other since last fall, so they are not strangers. Any suggestions?