I've got 6 silver laced wyandottes and since 6 weeks I've had an unknown feather picker. I've spotted blood on the roosts three times. Now they are at 10 weeks and there is still feather picking going on. The chickens are allowed to free range all day, at night I put them in the run with their coop. Their run is huge and the coop is a comfy 8' x 10'. I've been feeding them grower feed, they have access to grit, and anything they can find free ranging. The feathers are usually the smaller softer feathers, but every once in a while I find a longer wing feather. When I let them out of their run in the morning and clean their coop up, every other day there is a little pile of feathers in the corner. All of the chickens seem healthy, robust, and active. I'm so stumped. Any suggestions would be greatly appreciated!