You are on the right track. Although we cannot surmise if the swans may have been on the migratory path and got sidetracked or new parents looking for a suitable home, providing a safe, secure and welcoming habitat will at least make them feel at home. They may still leave during the winter months, but if they feel safe from predators (man and animals), have plenty to eat (cracked corn, poultry layer pellets, a little bread and lettuce), shelter, shade, etc., they should want to stay or at least continue coming back to the same area during migratory season. The Regal Swan