I have 3 Barred Rocks too. One has a regularly recurring bald spot similar to the one in your pic (based on what I can see) when the poop ball that gets matted to her butt feathers falls off and takes some of her feathers with her. I have tried to keep it from forming, but it doesn't take much. And it's such an ordeal to try and clean, I almost rip as many feathers out trying to save them as she loses just letting the darn thing fall off. Worse than gum in a child's hair. Have you noticed a poop ball stuck to her butt fluff? Keep an eye out. Chances are she'll probably develop another if that's the reason for the bald spot. I don't know why some have trouble with it and others don't. Probably lazy posture and small variations in body structure that doesn't allow them to get the angle downward enough. Or it's just laziness like men who pee on the toilet.
Is the bump above the vent hard? Or super soft like a pus-filled sac would be? If it's not either of those and feels like normal healthy tissue underneath, I'm thinking it's always there and it's simply something we can't see when they have their full compliment of feathers and haven't been self-mutilating.
Is the bump above the vent hard? Or super soft like a pus-filled sac would be? If it's not either of those and feels like normal healthy tissue underneath, I'm thinking it's always there and it's simply something we can't see when they have their full compliment of feathers and haven't been self-mutilating.
