How old is the one pictured? Could it be molting? IF you suspect it might be your rooster causing it, then the easiest solution is to separate him for awhile, until the feathers have grown back in. It will be easier to reintroduce him back into the flock, than to remove a hen, reintroduce her, and have to re-establish pecking order. Yes, you will get more roosters when you hatch, so prepare in advance as to what you are going to do. My bachelor pad consists of multiple, individual smaller coop/run areas, that are fine for one rooster. I have them separated with 1/2 x 1/2 inch hardware cloth, so they can't do any real pecking, or spur damage to their neighboring rooster.