If the weather in your area turns extremely hazardous during the winter, then the swan will likely leave and migrate further south. If you feed it, it may stay, but you will need to keep it inside or protect it if your pond freezes during the winter. Frozen ponds can be accessed by predators walking across the ice. Swans are basically sitting ducks on a frozen pond, not to mention that the birds cannot drink fresh water, preen or bathe. In fact, the swan could die from starvation, pneumonia from being so cold or drowning from the inability to get out from under the ice.

If your pond stays open during the winter and you can get friendly with the bird, then feeding it supplementally, cracked corn/poultry layer pellets and lettuce can help sustain the swan through the winter.

More than likely, this is a young swan that either got lost on the migratory path or needed a resting area before traveling to the winter migration area. The Regal Swan