We can't tell from this angle the species. It actually looks like a juvenile swan with the bill not colored, so unless you can get a better close-up, we can't identify the species at this time.

Provide the swan with poultry layer pellets mixed with cracked corn, lettuce and some small amounts of bread to see if the swan will eat. If it is a juvenile it may stay, but whether it is an adult or a juvenile, if it can fly, it probably will fly during migratory or nesting season. It may also succumb to predators if it is a juvenile and does not know how to protect itself. The Regal Swan