I first heard of "storm wigeons" from a coworker on a project in North Dakota. He was an obsessive hunter/fisher/trapper. He hunted everything you could possibly legally hunt, and unsurprisingly was made giddy by the area's abundant waterfowl.
If you are wondering what a storm wigeon is, this is it; an American Wigeon with a white head. Normally only the forecrown of an American Wigeon is white; on a storm wigeon, the white is much more extensive. Storm wigeons seem to be pretty rare (this is the first that I remember seeing) and are lusted after by hunters across the country.
Of course, I have no idea why they are called storm wigeons, but at least it's epic. But why do they exist? Some people think it's a rare variant of American Wigeon, some think it's more of a function of age (male and female Laysan Ducks, for example, get more white in the face as they get older). What do you think? At any rate, a very cool looking bird. Photographed at Bubbling Springs, Port Hueneme, CA.
Here is a more typical American Wigeon for comparison. Golden Gate Park, San Francisco, CA.