See if he will stay in the pond (as long as it is free from predators both wild and domestic, i.e., cats and humans). You can do this by making it extremely comfortable for him by providing food and having your neighbor or you constantly feed and making him understand that you are his caretakers and a safety net for him. If you do not want him to continue staying or if he tries to walk off, we would suggest that you take him to a local wildlife rehabilitation center and see if they can find him a good home or take him to an area with other juveniles. In any case, if someone is shooting them with a gun, it means that either they are wildlife officials who do not want feral mute swans in the area or someone getting their fun out of shooting a large swan. So, just turning him loose in an unprotected area will get him killed. Let us know how this progresses. The Regal Swan