According to Wikipedia (which is always right about everything):
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group (the group of all descendants of a single common ancestral species) but a form taxon, since swans and geese are not considered ducks. Ducks are mostly aquatic birds, mostly smaller than the swans and geese, and may be found in both fresh water and sea water.
Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes, gallinules, and coots.
So, sorry all you loons, divers, grebes, gallinules, and coots. This ain't for you. These songs are for the ducks.
This next one by the beautiful Carolina Cotton, makes me wish I was a damn duck!
Eddie "The Chief" Clearwater walks the duck
Nobody has really done musical justice to the duck as much as this disco classic from Rick Dees & His Cast of Idiots
OK, the next one is stretching it. It's not really about a duck. It's not really really about oysters either. It's an old traditional American square dance mutated before your very ears by the late great Malcom McLaren. It's from his masterpiece album Duck Rock. And if I were a duck, I'd love this song.
Finally, just for weirdness' sake, here's a strange little band called Purple Duck I found while messing around on the Free Music Archive (The original video I had here disappeared, but here's another one)