The feather picking is a big issue. You need to remove the injured chickens and place them in a rehab pen until they are better. And, police the area until you find the culprit because they will move on to the next chicken low in the pecking order. Then...remove the culprit or put peepers on that chicken. Also, anyone else that has red areas..spray with Blu Kote to cover up the red. Chickens can't resist pecking at red. And once they see blood...they won't stop. Also, try giving them something to do other then feather plucking. Scratch at straw, hang cabbage, a Flock Block. Try giving them extra protein like BOSS or scrambled eggs. Make sure they have enough room to get away from each other. Add another pen and put some roost bars in the pens. Good Luck. I hope your injured birds are ok.