By Emily Stone
Naturalist/Education Director, Cable Natural History Museum
The silhouettes of turkey vultures soaring above farm fields and highways kept me company recently on a long drive to Iowa. With snow still falling at home, these drab, brownish-black scavengers gave me hope that a new season is on its way—however haltingly.
Most people probably don’t associate turkey vultures with spring—or even realize that vultures may have flown as far as South America for the winter—but they are one of the earliest returning migrants. “What blazes the trail,” wrote Mary Oliver, “is not necessarily pretty.” Vultures need warm weather so that the smell of their food can rise skyward, and because it’s far easier to eat fresh roadkill than frozen dinners.
Just a few days after I arrived home again, I caught sight of the V-shaped wings and rocking, unsteady flight of a turkey vulture soaring above my road. I suppose the “buzzard” was trying to wait until temperatures increased enough for warm-air thermals to buoy up their gray-fingered wings.
Having thermals to lift the birds upward so that they can coast onward is far more essential to a turkey vulture’s migration than a tailwind. It’s so important to find thermals, in fact, that turkey vultures congregate in big migratory flocks that find invisible air currents. Since migrating in a big group means that there will never be enough food to go around, it’s a good thing that using thermals also significantly reduces the metabolic energy necessary for them to fly.
For as long as I can remember, Dad has been pointing out every turkey vulture (TVs he called them) soaring over every road trip we ever took. And it was fun, even as a kid, to be able to easily identify such a large bird flying so high up in the sky. They have an excellent gross-factor, too, which kids love. “Don’t get to close to a turkey vulture,” warned the park ranger on my first grade field trip to Effigy Mounds National Monument, “they’ll throw up all over you!” That I still clearly remember this fact, and the moment I learned it, validates my own love of using yucky facts to teach kids.
Since that day, I’ve discovered many more wonderfully revolting facts about turkey vultures.
First of all, projectile vomiting is a defense they use against predators, not just curious humans. The foul-smelling mix of semi-digested meat and digestive fluids can sting if it reaches the predator’s eyes. In addition, emptying their stomach may be necessary to lighten the load for take-off and escape if a TV is interrupted while gorging on a roadside carcass.
Turkey vultures don’t just spray gross stuff on enemies; they also defecate on their own legs. This habit has a scientific name (urohidrosis) and a valid purpose. As water evaporates from the combination of urine and feces (birds don’t separate their waste like we do) it cools the blood vessels in their legs and feet. The acidic liquid may also act as a disinfectant.
Even though they can’t sweat, vultures’ feathers sometimes become damp during dewy, foggy, or rainy nights. Then, while they wait for the air to warm enough to begin rising in thermals, TVs perch in a spread-winged stance in the sunshine. This not only dries feathers, but it warms their body, and bakes the bacteria off their feathers and bare, featherless head.
In addition to antibacterial behaviors, turkey vultures have developed excellent immune systems that can ward off and even destroy the microbes that cause botulism, anthrax, cholera, and salmonella. Their stomachs, gross as they may seem, help purify our world. Can you imagine a world in which dead things all rotted slowly in place? Turkey vultures embody the fact that “the secret name of every death is life again.” (Mary Oliver, Skunk Cabbage)
Despite their gross appearance, every adaptation of the turkey vulture seems aimed at cleanliness. How appropriate that the TVs’ scientific name—Cathartes aura—means “purifying breeze.”
The story of the vultures—of winter’s rotting wounds transformed and purified, of the purifier rising up into the sky, of it returning to cleanse the world again and again—sounds a lot like another story I often hear this time of year.
“Like large dark lazy butterflies they sweep over the glades looking for death, to eat it, to make it vanish, to make of it the miracle: resurrection…” from Vultures by Mary Oliver.
Author’s Note: Portions of this article are reprinted from a 2014 Natural Connections article.
Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.
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