I don't know if this is the same couple ( they all look alike) but every year about this time they show up for a swim. The Pool Guy (that's his company name) always wants me to shoo them away because he says they make a mess, but I'd really like them to stay. They never do, though and I don't shoo them away. At my previous house a couple moved in and had ducklings. It was fun to watch them enjoy the pool. A friend, who was watching my house while I was away, fashioned a ramp for them so that the ducklings could get out of the pool. He thought they were ready to leave but couldn't fly to get out on their own.