I have 5 hens that were brought up together and have done fine for the last 2 years. Then suddenly I noticed one black australorp hen picking on one of my easter eggers to the point she would hide. I separated the australorp for a week and then put her back into general population. Things did not change and now I noticed 4 were picking on the easter egger, I have had the easter egger isolated for about a month now. Every morning when I clean the coop and refuel I let them all out together and she stays away from the other hens. Today she went into the main coop and all 4 hens jumped on her and held her to the ground picking on her. I ran over and pulled them off her and grabbed her and got her out of there.
I don't know what to do, any suggestions would be helpful.