I have three RIR and one Lakenvelder (all hens) and two of the RIR's have missing feathers on their backs above their tails and below their vents. They are completely bald. The third RIR has full plumage, so she is obviously the troublemaker (or is she). They were all in a 4' x 6' cage through the winter in my garage, and all were fully feathered until a few weeks ago. I noticed the feather plucking and wasn't sure if it might have been self inflicted, but about a week ago, one of the RIR's had a hole about the size of a silver dollar and 1/4" deep just to the right of the plucked out area. I immediately confined her alone and took a wait and see approach and she appears to be healing steadily and has substantial feather regrowth. The other three have since gone into a chicken tractor (4' x 4' coop with covered 4' x 8' run) which we move twice a day. The second plucked out girl has no feather regrowth and so I pulled her out of the bunch tonight and put her in confinement. I am afraid that we may have contributed to the girls getting picked on, even though the winter quarters were 4' x 6' which is 24 square feet or 6 sq ft per bird. I was also hoping that getting them on pasture (grass) would have helped, but no feather regrowth in a week and a half so I think there is still a certain amount of feather picking going on. Does anyone have any recomendations?