A bird which is typically found in or near water; (in later use often) spec. any of the larger kinds of swimming birds, esp. those regarded as…

An animal that (habitually) swims, or whose structure is adapted for swimming; spec. a bird of the order Natatores, a swimming bird.

A waterbird (not identified, but probably the red-breasted merganser, Mergus serratus).

Any of various birds, esp. waders, that obtain their food from mud.