Every once in a while I find a pile of feathers in my chicken coop. Not scattered feathers like from one chicken bullying another - I've seen that before when one chicken had her tail feathers pulled out by another. But she didn't stand still and let them pull the feathers out all in the same place! These feathers are all in a bunch about the size of my hand. It's happend three or four times now. I can't tell which chicken they're coming from, either. None of them have bald patches. One does seem to be missing a good number of "under" feathers from her chest area, but not enough to account for all the feathers I've found lately. (And since the feathers are from her chest, it would mean she's plucking her own feathers, right?) None of the hens are broody. None seem to care about the plucked feathers. The feathers just sit there on top of the shavings in the general coop area. Any thoughts would be appreciated. It's below freezing temperatures at night now, I don't like the idea of my hens missing any feathers! If I need to change something to change this behavior, I would.