My wife and I took a walk tonight with our four grand children who are visiting with us. We walked along the canal road that I used to run a few years ago. We saw three sets of ducks and a total of 10 ducklings in the water.
The last group of ducks were black ducks. The adult accompanying the ducklings was totally black except for a large white spot on its neck and breast. It's head and beak were totally black. Because the duck and its ducklings were in the water, I couldn't see if their feet were webbed or not. There were 5 ducklings, and about half were totally black with the white spot, and the rest were totally black including the neck and breast. Usually with birds, the males are more colorful, and I would expect the ducks with the white spots to be males. However, it seems unusual that a male duck would be baby-sitting the ducklings. So, I'm not sure which sex has the white spot.
7/27/2008 Finally got some pictures of the black ducks. These ducks are the "ducklings". Some of them have the white spot, and some don't. Click an image for a larger view.