156 years ago almost to the day, in the American Civil War, in a confrontation known as the Battle of Hampton Roads, two ironclad warships--the USS Monitor and the CSS Merrimac--fought to a draw. After half a day of exchanging volleys, they limped back to their respective ports for repairs, having changed forever the way warships would be designed.

I can't help but think of the Monitor and the Merrimac every time I see the White-winged Scoter. If you've ever watched a bevy of these black birds fly in to join a mixed flock of other waterfowl, you'll know what I mean. Large and heavy looking, riding low in the water, with neck and head often resting low as well, they very much look the part of lumbering ironclad warships. They don't ride the waves; they plow through them on an even keel. Other birds in the flotilla make room, taking their places as support vessels to the big guns.

DSC_6044.jpg

The White-winged Scoter is not the largest of birds that you'll see floating on Lake Michigan, but its dark color makes it appear larger than it is. And its oversized, heavy beak adds to the bulk. It's not exactly a pretty beak, either. As the White-winged Scoter male matures, a bulge starts to grow at the base of his orange beak, similar to the way a tree that is planted too close to a sidewalk will slowly grow over the cement in a rounded bulge. Add to the adult male a bright white curved slit behind the eye and you end up with a pretty sinister-looking duck. When Hannibal Lecter was a child, if he had a bathtub toy, it probably looked like a White-winged Scoter.

The White-winged Scoter's similarity to the ironclads is more than feather deep. Belowdecks this bird is equipped with some powerful digestive equipment. Its main diet is mollusks, which it eats without the aid of a shucking knife or a steamer. It just swallows them whole--shell and all--maybe a dozen at a pop. Then, after feeding, as it sits there looking calm and nonchalant, its digestive machinery goes to work, sloshing its dinner from its "regular" stomach, with acids and enzymes like ours, to its gizzard, a muscular stomach that literally grinds everything to a pulp so it can be digested. The gizzard is what lets birds get by without teeth (or shucking knives), and the Scoter's gizzard is extra large and extra strong. In fact, it grows stronger and larger with use, like your bicep will grow if you do enough curls.

DSC_6491.jpg

Our comparison with the ironclads begins to take on water when the White-winged Scoter takes to the air. There is nothing lumbering about a scoter in the air. It is a very powerful flier. In fact, according to several sources, the name Scoter is derived from the old Norse word skjota (to shoot), because it flies like it was shot from a gun. Flocks of Scoters will often fly low over the water, in a long, curling line.

A closing thought about an unfortunate similarity between the White-winged Scoter and the Civil War era ironclads. Armor, munitions and power sources would evolve rapidly in the decades after the Monitor and the Merrimac saw active duty, and the ironclads were obsolete almost before the ink dried on their commissioning papers. Likewise, the White-winged Scoter has some serious vulnerabilities that make it especially susceptible to environmental changes. Its main diet, bivalves, literally soak up damaging toxins and heavy metals in the water, intensifying the harmful impact of these substances on the Scoter. The Scoter's strong tendency to return to prior years breeding sites means human encroachment on the dense shoreline vegetation where they build their nests can completely prevent some pairs from breeding, and nest location and feeding habits makes oil spills especially disastrous. Finally, compared to other waterfowl, the White-winged Scoter chicks take exceptionally long to mature to flight capability (more than two months). The overall survival rate of the spring breeding season is estimated to be somewhere between 1% and 10%. Those are not good odds.

DSC_8584.jpg

For the moment, though, the White-winged Scoter is holding its own. In fact, the zebra mussels that have invaded the Great Lakes have proven to be a welcome food source for the Scoter, so the number that spend their winters here is increasing. You may have a chance to see a few still this month, before they head back to northwestern Canada and Alaska, where they'll lay their eggs and try to beat the odds.

Dan's Feathursday Feature is a weekly contribution to the COS blog featuring the thoughts, insights and pictures of Chicago birder, Dan Lory on birds of the Chicago region.