Hi, we live alongside the River Eden and my ducks and geese use this every day and return to our land at various times during the day, I also have 3 Indian Runners amongst them. The secret is when you first get them keep them in their pen for a few weeks, the longer the better. Once they are settled with you they know where home is and are happy that you are going to feed them they shoudl come home. As to putting themselves to bed at night, I doubt that very much.
The river Eden is tidal and wide beside us and the ducks happily co exist with the swans, wild ducks and geese, seals and various other wild birds.