About two weeks ago I noticed that one of my BO hens had a bald spot on her rump, it was about the size of an egg funnily enough, but lower than her vent. I felt it and it felt a little like there might be an egg behind it. She wasn't acting bothered by it so I decided to watch it. No one else had any spots. The next day she had a spot on the side of her chest that was bald with a little cut on it. I didn't know if she had done it to herself or someone else. I see very little squabbling and have never seen pecking, but I know they can be sneaky. But I thought maybe she was in pain from something going on on her behind and was pecking herself. She never acted any differently though. The feathers on her chest are growing back but her butt is still bald and the skin looks a little red. NOW, In the past three days I have noticed 3 more chickens with bald spots. One EE I noticed had a bald spot near the base of her tail the other day. She is one of the more dominant ones and always gets the prime roost spot she wants. Again not showing any symptoms. Today I noticed a brown leghorn had the same bareness at the base of her tail (on her back) with a little blood on it. AND one of my RIR has the same bald butt as the BO. It has been really cold here for the last few weeks and I think this all might have started when i started using a red heatlamp at night. The problem is now I have these chickens with bald spots and it is getting down to 10 degrees tonight, so i feel like i can't try turning the heatlamp off. I was just out there tonight with a headlamp looking for mites, but I don't know what I'm looking for exactly. I didn't see any bugs or moving things on them- I looked mostly around the bald areas. If it is a pecker, how do I catch the perpetrator? I have 10 hens in all, no rooster. They get oyster shell, organic layer pellets, a little corn daily. Before this started they got a lot of pumpkin from leftover pumpkins from halloween. Routinely they get some greens I buy at the store a few times a week, once in a while some leftover cooked rice or oatmeal, and yogurt and flaxmeal once a week. They have pine chips in the bottom of the coop, deep litter, roosts high above this. The heat lamp points down under the roost so the heat can rise, but the light isn't pointing on them. They have all been laying almost every day still, except for a completely feathered EE that decided to go broody at the same time as all this was happening and stopped laying- a whole story to itself that has been fairly amusing actually. Another element i just though of is that i use a poop shelf below the roost. This allows me to keep the coop cleaner, but it also allows chickens to walk or sit right behind another chicken who is roosting. What I am imagining is one chicken sitting on the roost and one chicken sitting on the poop shelf with its head right by anothers butt, picking maybe? Any thoughts on what is causing it and more importantly how to stop it are greatly appreciated.