We just acquired a new flock of chickens. A total of 8 came together and we already had one hen and a rooster. One of the newer hens is an amercauna. She is smaller then all of the rest (red sex link, black sex link, silver laced, favorelles) and they all seem to pick on her. She plays dead (she will lay right down and put her head down for a couple minutes) when they go near her. Any suggestions to get them to stop picking on her?