That is now my understanding as well. My question had been how long one needed to let the area be fallow (e.g., free of any wild birds) before it was "safe" for our ducks, but my research leads me to believe that the virus remains active in manure for 3+ months. So that eliminates the moveable run idea unless we had a floor or did something practive to clean the floor area. Ugh.I think because they could be grazing where a wild bird pooped if the tractor was moved. It’s a good question.