I agree with @Debbie292d this looks like plucking, another bird is pulling out her feathers. Does she roost higher than another bird so that the bird below might be plucking her feathers out?Thank you everybody!! I really appreciate it. I posted my first question in a forum but will post it here too.. is this mites/lice or nothing to worry about? It’s in the vent area of some of my chickens. I don’t see any little bugs anywhere tho.