Waterfowl

Waterfowl are any type of bird that spends a lot of its life in or near water. However, it mostly refers to the family Anatidae, which are ducks, geese and swans.
The term can be used more widely to include birds such as coots, grebes, moorhens, shorebirds and seabirds.
A very similar term is "water bird", which is used in contrast to waders, which walk about in shallow water.