I have spent a lot of time reading about feather picking and how to stop it. I have 10 chickens total, 2 are americanas that are missing feathers over their backs and wing tips. They have been missing for over a year. I got rid of an extremely mean BR hen this spring that I thought was the picker. I have tried the dog food-extra protein trick, the blue kote spray over the bare patches, the pine tar.....every trick I have read on this site, and still no feather regrowth. I have spent hours in the coop, watching them, I can't identify the picker. They free range all day and aren't bored. Maybe they are preening themselves to vigorously?? Is is possible they have been featherless so long, their feather 'folicles'? have forgotten how to grow feathers?? I even had to put sunblock on the bare spots because they were getting sunburnt, honestly..........I know, my DH thinks I'm nuts too. They are ugly and I am sad. Any further ideas before I start the "How to cope with/accept chronic feather loss" 12 step program?