There are several reasons for this behavior. The swan may have gotten tired of flying and landed in the nearby area or was walking to look for another pond. If it had been raining, sometimes swans will land on slick roads because it looks like a stream/river to them.

If neither of these were the case, then it might have been a juvenile from this year which was chased by a nearby pond by swan inhabitants and told to find another pond. Is there anyone in your area that might have swans or ponds with swans that it might have become disoriented? If so, you might check with the owners and see if they are missing a swan so they can begin a search.

More than likely, the swan got its rest and proceeded on its journey. The Regal Swan