I have a flock of two and I am attempting to add a third. The third hen (Squeaky) has been with us a little over a week. I keep her in a big dog cage next to the regular coop. Robin a bigger hen keeps attempting to attack Squeaky in her pen. I switch the hens between the coop and the dog cage - Squeaky in coop other Robin and Lilly in the dog cage; then switch in couple hours. I have had all three out in the yard so it was less territorial but when Robin sees Squeaky she will race across the yard to get her. Robin has jumped on Squeaky and savagely started pecking her head. I keep them separated but I sit in the coop area and let them out together once in a while. Robin is obsessive! What can I do? Have I made a mistake bringing in Squeaky?