I had this same issue when I introduced my RIR Emma to my little flock of three. I could tell who was who on the pecking order, My BR Zoii was the queen of the flock and everybody knew it. And then there was my EEs Gladys and Ginger. After her quarentine, Emma's coop and run was moved next to the Big Coop so they could get used to one another. Apparently, I didn't leave them alone long enough. When I put Emma in for the first time, Zoii ignored her and Gladys and Ginger attacked her. I had no choice but to separate her (they had not only pulled feathers, but drew blood). We separated Emma for a week or so more and tried it again with the same result. So I resulted to HorseFeather's method- I took Gladys and Ginger out of the Big Coop and put them in the quarentine coop. That left Zoii and Emma to get to know each other. They stayed like that for a couple of weeks, Zoii and Emma got along really well. Then one night, we moved Gladys and Ginger back to the Big Coop. They woke up the next morning thinking they were completly new birds! They fought alittle, pecked and what not and after a few days of staying out of it and watching, they formed a new pecking order. Separation worked for me. Try taking your new birdie and confining it with one of your established flock. Then a week later (or when they are no longer pecking at each other and roost together) re-introduce the other bird. Then they will bicker and fight a little and form a new pecking order. I think the hardest part of this method is trying to stand back and let them squabble and fight it out for a couple of days. I hope that whatever you decide to do, it works out for you and your chooks. Good luck!
