Over the past week or two, the swans have been joined by approximately a dozen American Coots. No matter where the swans go, the Coots are sure to follow. They seem to be living together harmoniously, with no territorial problems from either side.
One guess I have is that the Coots are "hanging" with the swans so that they can benefit from the food that the swans are digging up from the bottom of the pond. But this is purely a guess on my part.