freshwater aquatic bird
"The herons and ducks we saw wading through the pond were just a few of the many waterfowl migrating south for the winter."
Any of the birds, such as ducks, geese and swans, that spend most of their non-flying time on water; especially those of the family Anatidae.
"The marsh was teeming with waterfowl like mallards and Canada geese feeding near the reeds at dawn."
The word comes from Middle English, where it was formed by combining "water" and "fowl." Its earliest ancestor in Old English literally meant a bird that dips.