I have been watching this mallard couple swim in my above ground food since March. They were eating the organisms growing on top of the cover. They seem to come back each year, but when the cover comes off, we no longer see them. Well, I guess the heat is getting to the ducks too because I just found them taking a dip in the pool! They were swimming and bathing and enjoying the water! What a funny thing to come across in your own backyard!