There have been a lot of Muscovies released into the wild and have become an invasive species in the South, especially Florida. There was talk of bans on them a few years ago because of this. My brother worked in the Fish and Wildlife Service and told me about all this when I was discussing breeds with him one time. The quality of being such good brooders and mothers makes them great for keeping on the farm, but if they get out in the wild, they can quickly take over the natural habitat of other waterfowl. Just one more reason too, to clip your wings on waterfowl and keep them home. Mallards are a wild specie, but more than one Call duck keeper has gone out to find their little Calls have flown to coop to join their wild cousins, but those are ducks not accustomed to life in the wild and often end up food for other critters.