So one of my ducks has a patch on his neck where all the feathers are falling out. There are just down feathers left. It's not from mating, he is the only drake. A couple months ago (at least 6) he did get a cut there and I clipped some feathers to see better but this patch is much larger than where I clipped and the cut was minor. Any idea what this could be? I can't seem to move the down enough to see to his skin but I would think if it was an infection or something, the down would fall out too...