I have over fifty water contains for my chickens around the property and a pond they can drink out of. Last week I notice that one contain was covered and full of poop. I took it to the house to clean and checked all the rest, nothing all clean. The nest day I put the clean container back in a different spot, when I checked the container the following day, it was full of poop again. I have cleaned this container three times and placed it in a different spot each time only to found it dirty the next day. It is like they roost on it. Has anyone else ever had this happen? It is only this one container that they dirty. I have seen them do something like this when cooped up all the time, but never when free ranged.