I noticed today that several of my hens are missing feathers on their undersides, starting a couple inches from the vent and going all the way up to their crops. It's not a lot, as you can't see the bald spots without pulling the feathers around them back, but it's concerning me. It looks just like my broody does when she's sitting eggs and plucks to keep them warm, except non of these gals act broody at all. At first I suspected feather picking but it's in such a hard to reach area and is on some of the top hens. I know my head hen didn't do it because she's broody right now and has never pulled feathers that I've ever seen. I watch my ladies a lot and I haven't seen any abnormal behavior. What the heck? Any ideas?