It's possible the other duck could be doing this, or she might doing it herself. If she's doing it herself, I highly doubt she's doing it intentionally. It's more likely that she has parasites like mites.@ryneaeiel I might be able to, though she does like to roam around and she doesn't like being enclosed. I don't have any other animals, and I only have one other duck. I've never seen her or the other duck fight. They've always been super nice to each other and even go out to look for earthworms together.