Turkey vultures

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(HOST) Commentator Ted Levin has been keeping track of various birds as they begin to migrate south for the winter, and he says that watching one of our most attractive fliers almost makes him forget about their most unattractive eating habits.

(LEVIN) As I drove south from Thetford on I-91 the other afternoon I spotted more than a dozen turkey vultures high above the mouth of the Ompompanoosuc River, cutting great lazy circles across the sky.

No other bird in Vermont has the turkey vulture’s command of the wind. No other bird soars for hours so easily, the corrugated landscape passing below it, scarcely flexing its wings, gently rocking back and forth like a kite on a string.

The Buoyancy Index, a mathematical expression of a bird’s ability to glide, which is derived by dividing the cube root of the body weight into the square root of the wing area, reaches the highest value for Vermont birds in the turkey vulture, with an average index of 5.81. Which essentially says, the bird is light in comparison to the surface area of its wings.

Peregrine falcons, swift and powerful, have a much lower Buoyancy Index, 3.98. And loons, solid-boned, heavy, and small-winged, have the soaring ability of a Buick. Their Buoyancy Index is much closer to two. In fact, if a loon’s flight speed is sixty mph; its stall out speed is fifty-nine. Loons do their soaring underwater.

The grace of the turkey vulture was not always part of Vermont’s airways. Their arrival in the Northeast in the mid-1970s followed the completion of Interstate 89 and 91. Ribbons of warm air rising off the dark face of the sun-heated highways lured the birds out of southern New England. In 1981, the first nesting in NH was confirmed in West Lebanon. And in Vermont, in 1983, in northwestern Franklin County. Now they’re everywhere, a fixture in the summer sky. And by late September they gather in swarms above the interstate, slowly drifting south.

In the 1960s, a West Coast biologist proved that turkey vultures could smell carrion, correcting a long-standing debate that had begun with John James Audubon, who claimed vultures were more interested in his painting of an eviserated sheep then in the actual carcass hidden beneath the leaves. The biologist concealed a dead animal under a tarp and attached a blower to a hidden carcass, wafting the odors skyward. Each day a congregation of vultures gathered around the unit, anticipating lunch.

A late September cold front moving out of Canada and across the Great Lakes pushes turkey vultures into view. I watch them as they ride the wind for hours searching for carrion, bloodhounds of the bird world; rising and sinking, always gliding, always tilting.

Watching them, it’s easy to forget what they eat.

Ted Levin is a writer and photographer and winner of the 2004 Burroughs Medal for Nature Writing.

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