Feather Picking (?)

I’m looking for what has worked with other people to solve feather picking.

I have 8 laying hens, all about 1 year old. They spend most of the day in a 12x12 screened off area.

All of their butts, except one hen who looks fine, are bare. Most of the front of the necks are also bare. Generally the exposed skin is not irritated-looking, but in the last few days I’ve noticed increased irritation levels.

I’ve ruled out mites. I’ve watched my birds quite a bit and have seen them pick themselves and each other. Are they bored? Is their area too small? I feel stuck!