About the Cable Natural History Museum:
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.
Contrary to folklore, vultures don’t necessarily circle around dead things. When you see a kettle of vultures circling high in the sky it likely means that they have found a rising column of warm air, called a thermal, to ride on. From there, they might be able to smell their next meal. / Photo by Larry Stone
What signs of spring have you spotted lately?
About a month ago, my dad reported seeing his first turkey vulture of the year down in Iowa. Most people probably don’t associate these drab, brownish-black scavengers 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,” writes Mary Oliver, “is not necessarily pretty.”
Sure enough, a few weeks after dad’s report, I caught sight of the V-shaped wings and rocking, unsteady flight of a turkey vulture soaring above my road. I suppose the 'buzzard' had to wait until temperatures increased enough for warm-air thermals to rise and buoy up its gray-fingered wings.
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, is an excellent argument for outdoor education.
Since that day, I’ve discovered many more gross 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. It’s quite handy, actually, if you can’t sweat.
Even without sweating, 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 off bacteria.
Not everyone sees vultures as a gross. Tibetan Buddhists practice “sky burials,” where vultures consume the dead, and Buddhists respect the birds for their role in cleansing the earth and continuing the food chain.
While their diet of rotting meat may repulse us, turkey vultures dispose of carcasses that could otherwise breed disease. 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)
In response to their diet, TVs 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.
Indeed, despite their gross appearance, every adaptation of the turkey vulture seems aimed at cleanliness and purification. Even their bare, ugly heads serve to keep turkey vultures clean. While they are feeding on those carcasses, TVs sometimes need to stick their heads deep into the cavities of the dead animals. They preen the rest of their body feathers frequently, but can’t clean their own head. The lack of feathers allows sunlight to sterilize their skin.
While we don’t usually think of urine as cleansing, turkey vulture urine helps to kill bacteria they might have acquired while walking over a dead animal.
So although they may appear gross, TVs’ scientific name -- Cathartes aura—is quite appropriate. It means “purifying breeze.”
And in fact, 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.
Read more posts from Emily Stone.
Emily Stone is a Naturalist/Educator at the Cable Natural History Museum. Visit http://www.cablemuseum.org to learn more about exhibits and programs at the museum. For more from Emily Stone, visit her blog at http://cablemuseumnaturalconnections.blogspot.com/.