OK, so we have a Red Star hen named Abby, along with 3 other Red Stars and a RIR rooster. We got Abby, along with her friend, Penny, from a friend. Both were in terrible condition; very bad leg mites, loss of a lot of feathers, etc. And they were very shy. Abby and Penny look much better now. Abby is still shy, but Penny is much more friendly. And now I've noticed a problem with Abby; she almost constantly pecks the other chicken's rear ends and tail feathers, every chance she gets! She even pecks at Marty, the roosters', butt! While he's eating, she will come up behind him and peck him. Poor guy. She does the same thing with the others. What do we do about this mean hen?