They leave for the winter, they are "smart swans"...
When they come back during spring and summer they come back slowly.
2 or 4 at first, on my next visit I see 10 and then there are 30 or more swans swimming about.
Mute Swans are large unmistakable water birds,
common in the northeast, seen in most of our many lakes and they are even seen in ornamental ponds.
It's neck is held curved when swimming, the wings make a humming/throbbing sound when in flight.
Often seen in pairs, sexes are similar and difficult to tell apart...they mate for life.