For some reason, I’ve always loved vultures.
Broadly, their taxonomic group includes turkey vultures, black vultures, and relatives such as California and Andean condors. In prehistoric times, there was even a giant condor in North America with a powerful bill and a wingspan of 17 feet. That’s the length of a small-sized school bus!
All of them have a number of features in common: featherless heads and necks; long, broad wings; stiff tails; slightly hooked beaks; and clawed but weak feet. Many of them also have the unusual habit of defecating on their legs to cool them evaporatively, a behavior called urohidrosis. Storks do this, too, a point used by some ornithologists to suggest a close evolutionary relationship between these two groups.
The scientific name of their family is Cathartidae, a term derived from cathartes, a Greek word that translates roughly as “I purify.” As scavengers, they gulp down carrion, fruit, eggs, and garbage like living, hissing vacuum cleaners for the natural world. The turkey vulture has a highly developed sense of smell for detecting ethyl mercaptan, a characteristic but repugnant gas produced by the rotting flesh of dead animals. Other species such as the black vulture have a weak sense of smell and so find their food by sight, but they’re often clued by the indicative behaviors of turkey vultures. Regardless, the bald heads of vultures are a twofold adaptation for thermoregulation and for feeding on dead stuff. As they stick their heads deep into decomposing carcasses, tissue and sinew will not get caught in feathers; and their naked skin can later be disinfected by sunlight. Their ecological niche to purify the landscape is a blessing recognized by diverse cultures around the world, including ancient Egypt – the recent troubles of some farmers and residents in southwestern Virginia notwithstanding.
Years ago, I led a backpacking expedition along the Potomac River from its source in West Virginia’s panhandle to a point near its mouth into the Chesapeake Bay. While in the Washington, DC area, our group camped by the river’s shoreline in Great Falls at the base of a well-known cliff. While exploring the nooks and crannies of the rocky face, Melissa, one of my more precocious students, raised herself over a ledge and stared directly into the eyes of a turkey vulture chick. She then learned intimately about one of its most effective defensive behaviors: with breathtaking accuracy, the surprised little bird – looking for all the world like a young turkey – disgorged its stomach contents on the face and shoulders of my student, just missing her eyes and mouth. Can you imagine her bewilderment … and the stench?
Vulture stomach acid is exceptionally corrosive to allow them to digest putrid carcasses that might be infected with nasty strains of bacteria such as botulinum, cholera, and anthrax. This adaptation also enables them to use their malodorous vomit as defensive projectiles when threatened. After regaining her bearings, Melissa became ecstatic about the encounter and quickly labeled it a “bazooka barf.” “I could even make out the remains of a liver and something that looked like a lung,” she exclaimed to our group. Of course, we all went back to the spot of the attack and found reeking flesh all over the ledge. The bird had run off to a distant spot and watched us from afar. Later we departed with a renewed appreciation for all that vultures do for our planet.
The natural world is not always about lovely landscapes, heart-warming wildlife drama, and bouquets of pretty wildflowers. The natural world is a 3.5-million-year-old web of life on Earth that doesn’t give a hoot about our sensitivities and predilections. Vultures are just one of the principal fibers of that complex web with all its glorious diversity: 30 million different kinds of living things of which we humans are “E Pluribus Unum,” one out of many. I purify. That could be an aspiration for humankind as we attempt to countermand the far-reaching, relentless effects of our abuse of the planet’s resources.By H. Bruce Rinker, Ph.D. Science Department Chairman [email protected]