If the swan is a juvenile, the parents chased it from the habitat in September and/or it was on the migratory path and got lost. Once the cold weather begins, it will try to find warmer weather and should leave. If he does not, you may have to see if someone may rescue the swan should it get landlocked on the ice as it will be susceptible to predation, dehydration, starvation or drowning.

Having said that, you may need to be careful reporting the swan because in some states, wildlife officials will kill it or have it euthanized. They do so because they want to empty the habitats from Mute Swans so that they can introduce the larger Trumpeter Swans for Trophy Waterfowl hunting purposes. So, you may want to be very discreet in asking for help (such as wildlife or waterfowl sanctuaries/rehabilitation centers) should intervention be required. The Regal Swan