Girls missing feathers. Pecking?

[216 chickens]

I have 6 ISA browns. They are all the same age, 15 months. All of them are missing feathers on their chests and bottoms. They look ridiculous lol! I have witnessed them picking the feathers off of one another so I'm fairly certain that is the cause. I check regularly for mites. How can I prevent this from happening? My brother built their coop and run. Coop is probably 4 ft x 4 ft and run is 4ft x 15 ft. I can tell who the bigger bullies are because they aren't missing as many feathers as the others. Also, when I close them up for the night, I see usually 1 sometimes 2 hens are sleeping on the coop floor instead of the roost. Weirdos are stressing me out!

 

[Mattemma]

I spray bald spots with blukote and was told to give them sunflower seeds. Maybe add some more foods and roost/play options to the run. I always pulled bullies and crated for a bit to change the pecking order. Sometimes I just craiglisted the bullies.

I have had hens on the floor or in a nestbox at night. I would place them upon the 2x4 roosting board. My coop is a junky old metal shed 6x8. All 15 fit on the 2x4, but need to be let out asap in the am.No bullies for me so far with this flock,but a few bare backs thanks to our roo Vegeeta.