I have 8 chickens that are all about 1.5 years old. I have 2 RR, 2 Easter Egg Layers, 2 Barred Rocks, a wyandotte and an australorp. The two EE's are slightly smaller than the rest and they are the ones getting picked on. 5 of the chickens came together then I added the 2 barred rocks and the wyandotte a few months later. The pecking started a couple months after that. They have pecked the one EE more than the other. She has 2 bare spots on her wings but her other EE buddy is starting to get bare spots too now. They have never pecked so much that there has been blood but it has been going on for a month or so at this point. Today we put Bagbalm on their bare spots to dissuade more pecking and to help them heal and re-feather. I also added 1 TBS vinegar / gallon to their water. I read that this sometimes helps if there is a vitamin deficiency. Our girls have a lot of space. They free-range over a 1/4 acres at a minimum but typically have access to our entire yard which is more than an acre. I have noticed bullying when I bring goodies out for the girls to eat ... but never pecking that pulls out feathers. I believe the feather pecking happens at night when they are roosting and settling in together. Their coop is about 10 x 14 with plenty of roosting space and at least 10 nesting boxes. When they sleep at night the girls take up less than half of the roosting space. In addition to their coop they have access to a fenced pen that is about 20 x 15. They spend a few hours in the morning with only access to their coop and pen before we open their gate to let them free-range from about 9 am until dusk. So I doubt that space is the problem. I've been reading a lot of posts on the forum and have read that you can separate the picked on chickens out and let them heal and then reintroduce them to the flock. But I have also read that you can cull out the aggressive birds and then reintroduce them individually and they will then get a different pecking order when they return one by one. I'm leaning towards culling out the aggressive birds (the 2 BR's and the wyandotte) ... but wanted to get input from more experienced owners.