Please research "depluming mites" on BYC. You cannot see them because they stay beneath the skin at the shaft of the feather. They drive the chickens insane. First the chickens peck themselves at the base of the tail and, when blood shows, they peck each other. It looks like cannibalism but it is not. I was able to fix this by immersing in a bath of water and dog flea shampoo (it must have permethrin in it). Anyway, research here at BYC and check it out on the open internet. Make sure to be able to dry them after the bath.
Thanks for the info. I researched depluming mites, and I don't think this is my issue; however I have not ruled it out. My peepers just came, & unfortunately due to long work hours this week, we have not gotten to put them on Bertha yet. I really hope they sole the problem as I feel terrible about keeping her by herself. She was free ranging for one day with Percy, and it did not take long until I caught her pecking Percy's butt & causing her to bleed again. Other than that, they play so well together; always side by side. I hope to have the peepers on by this weekend, and I will let you all know how it goes.