Dark and light pair of ducks with curved tail feathers (1 Viewer)

Photographed today Oct. 1, 2011, in Wareham, Mass., USA. We've lived on the brackish Buzzards Bay inlet called the Crooked River (a tributary of the Wareham River in Massachusetts) for ten years and have seen all sorts of geese, brants, mergansers and various ducks, but have never before seen a pair like this. Obviously a mating pair, they always stick close together. Both have curled tail feathers. The lighter-colored bird has a small tuft on the back of the head, almost like a merganser -- but we have never seen them dive over several weeks observation. Also, they are sometimes closely accompanied by young (smaller ducks) but are usually swimming together alone. Can you tell us their name?
Thanks,
David

Some kind of domestic Mallards.

Barnyard ducks (domestic Mallards). The curved tail feathers indicate they're both males.

http://www.talking-naturally.co.uk/manky-mallards-domestic-feral-plain-odd-mallards/ (escaped barnyard ducks in general)
http://www.flickr.com/photos/fugl/sets/72157627356229183/ (crested duck)

Thank you, whitetail and fugl -- you are obviously correct. That explains why we couldn't find them in any of our wild bird books!

Thanks,
David