We are having an issue with butt picking in our coop. We have 4 hens (2 years) who are at the top of the pecking order, then 9 pullets who will be 1 year old in April. One of the pullets, a black australorp, 5th in the pecking order, recently started this horrible habit of butt picking. I've heard that the lower ranking chickens are usually the ones who get their butts picked, but it isn't the case here. She mostly pecks the older 4's butt feathers. This started when they were all molting. Now the other black australorp who is at the bottom of the order does it, along with a red sex link, who is second to last. The 4 speckled sussexes have caught on by now, and will usually go after them if they come close, but when their backs are turned it still happens. We actually now have a bare butt cuckoo maran, and a buff orpington with a sore on her butt. (She is now separated) We had a broody hen who just finished with her chicks, and she was up on a perch, and the australorp was actually following her around from the ground looking up at her butt feathers. Right now all 3 are in a cage because we don't want to cull them, but don't know what to do! They are our pets, so we really don't want to do that. Anyone have ideas on what to do to stop this?