Wednesday, April 4, 2012

The March of the Coots

At Lake Byllesby on Sunday, while we also saw both blue-winged and first-of-the-season green-winged teals, northern shovelers and our first American white pelicans of the year, by far the most prevalent bird was the American coot. We first saw about 70 of the black, duck-like aquatic birds near us on the northwest side of the lake. Later, while scanning the lake through the spotting scope, we counted at least 200 more along one of the far shores.

The march of the coots -- moving steadily westward in the shallows

I was interested to see the nearby flock leave the swimming-depth water and move steadily across the wet mudflats (see photo above), where they probed the water (and perhaps the mud) for food with their bills, just as shorebirds like sandpipers do. I haven't seen this behavior in coots before. The impression of all these birds walking in one main direction was like a herd of migrating mammals.

Coots behaving like shorebirds

Although they look like small black ducks with pointed white bills, and they swim like ducks too, coots actually belong to the rail family (Rallidae). Other members of this family include the rails, sora and moorhens. Coots don't have webbed feet like ducks; they have large feet with lobed toes. They mainly eat aquatic plants although, as shown here, they also eat crustaceans, insects, snails and other small aquatic creatures.

More typical coot behavior at the Superior Drive pond in Northfield

Coots are very common throughout almost all of North America -- year-round residents in most of the south-central and western United States, far western Canada and most of Mexico, summer residents in the north-central states and Canada, and winter residents in the southeastern U.S., the west coast of Canada, coastal Mexico, and Central America. In the winter they can form huge flocks, measuring in the thousands. I have never seen that, but Sunday's sighting of 270+ birds at once was quite an impressive sight in its own right.

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