Not sure what this might be. My white Americana has had a wet black butt for a few weeks now. I have 26 chickens and they free range during the day on 8 acres. During the evenings they are in a clean coop with a 50' run. I feed them Purina Pellets. Would love to know if anyone has any ideas what could be wrong. I am willing to do more research if I knew what to look up.