I have a few hens and my rooster with poopy butts. I've never really had this before but I do know how to clean it. I did a search here and didn't find any conversations about why this happens. Could it be worms? Diet? They are eating the same thing as always. Weather is cold alternating with wet and they do seem to be extra dirty this winter. Out of 30 birds, 8 have messy bottoms.