first thing I thought of was a coot also because they dive a lot. Since I love to birdwatch, I actually know more about wild ducks than domestic ones! Here's a link to another shot of one, http://www.1000birds.com/stocklist-American-Coot.htm and here's an article with more info about them: http://www.sdakotabirds.com/species/american_coot_info.htm