Fright without flight

Jim Williams, Special To The Sta

American coot flapping its wings

American coots have wings designed for flying long distances, not for quick takeoffs. That can make these small, chubby birds surprisingly vulnerable.

Last update: September 29, 2009 - 11:58 AM

American coots are among those bird species with a high wing load. Which means each square inch of wing surface carries proportionately more of the bird's weight. Which means coots have to run hard and long across the water to gain liftoff. Which can mean trouble (more on that later).

These small, dark, chubby birds gather in spring and fall in flocks that can number in the hundreds or thousands. You can see them right now on lakes around the Twin Cities -- Lake Calhoun, Lake Harriet, Medicine Lake, Parker's Lake and often in huge flocks on Lake Minnetonka.

Coots mutter among themselves as they feed on water plants. If you bother them, they'll stop their muttering and swim a short distance away. If you really bother them, they'll either dive underwater or hoist their butts out of the water and, with large splayed feet, run like mad.

Disturb a mallard and it jumps out of the water and flies away. Coots will run, not fly, because it costs them significant energy to get airborne. Once aloft, however, their wing shape enables them to be efficient in long-distance flight. Wing shape is essential to our story.

A kestrel, which hovers as it searches for prey, has long and narrow wings. A Cooper's hawk, which needs precision flight as it chases a chickadee through the woods, has wings that are short and rounded. The shape of a coot's wings are in between -- not long and narrow, not short and rounded. But because the wings are small relative to the bird's weight, a coot doesn't do quick liftoffs. This can be deadly.

Captive coots

A few years ago, I was patrolling Crex Meadows Wildlife Area near Grantsburg, Wis. It was late October and cold. Most of the ponds and lakes in the area were covered with new ice. One lake had a narrow strip of open water that stretched for about 80 feet. In that open water swam a few dozen coots. On the ice around it stood about a dozen bald eagles.

The coots, which should have been flying to their winter grounds along the East and Gulf coasts, had a big problem: That short stretch of open water wasn't enough for them to gain the speed needed for flight. They were trapped.

The eagles, on the other hand, had a buffet lunch.

One by one, an eagle would take to the air, line itself up with the narrowing strip of open water, and glide in, talons extended. Some of the coots dove. Others frantically swam to the far end of the open water. They bunched up there, a clot of coots pushing each other against the edge of ice. Now and then, a coot would be pushed out of water, onto the ice, an easy target.

The eagles flew away with their kicking prey.

Eagles, you see, have a wing shape perfectly suited to that situation.

Jim Williams, a lifelong birder, is a member of the American Birding Association, Ducks Unlimited, Pheasants Forever and Delta Waterfowl. Join his conversation about birds at www.startribune.com/wingnut. He can be reached by e-mail at two-jays@att.net.

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