Welcome to Backyard Chickens! We are glad you joined the flock! BYC is a helpful site providing all the information you need to know about poultry! There is always space for more members on the BYC roost! Molting could possibly be a factor. My chickens always go through that period this time of season. Hope you enjoy it here as much as we all do!
agree with Sourland. The birds that are untouched, are the ones doing the feather plucking. Shame on them. If you can move them elsewhere - you should see a return of feathers to the poor plucked ones.