I'm not sure this is even an injury or disease question because it could just be molting ... and as a newbie I'm not familiar with how that looks: Our flock just started to lay in August. We have 60 chickens representing several breeds in the "General Population" area of the coop/run. One breed in particular (but a few individuals from other breeds) is getting what looks like "bulls-eye butt." By this I mean the feathers at the base of the back just above the tail are disappearing. On one Brown Leghorn hen, I noticed this featherless situation has progressed all the way around her behind, and there are a few long tail feathers sticking out the middle. If I weren't worried I would say it is very amusing looking. But I'm worried. This is even happening on the rooster, otherwise I'd might think it is mating related. In addition to the bare behind thing, there was an incident yesterday with a rooster we keep separated getting in with the General Population and going after our top roo ... which is the Brown Leghorn rooster I'm describing. Now there are some very minor looking blood spots in that naked area (which we've treated cuz the hens were starting to pick on him when his back was turned). So that situation is both the same and also different from the rest. We've checked for visible pests, and can see none. The birds seem to be happy and energetic and are laying quite well ... the BLHs are giving us more and bigger eggs each day/week, so they don't seem to be in distress. I'll try to post some photos. But I'm sure you can imagine it isn't the easiest photo project! Any ideas?