They’re a stock image of the Southwest: vultures perched on saguaros waiting for our thirst-racked hero, crawling through the hot sand, to expire — or circling expectantly over a lost party of pioneers waylaid by bandits on the plains. We associate vultures so indelibly with the Wild West that it sometimes comes as a surprise to see so many of them here in Maryland.
Vultures come in two flavors in North America, and both occur here in the East. The larger of the two is the turkey vulture (Cathartes aura); with its bare, bright red head and neck atop a black body, an adult is unmistakable for any other local bird of prey. Larger than any of our local hawks, turkey vultures approach the size and heft of a bald eagle, with long wings designed to catch updrafts of warm air rising from hot asphalt, bare fields and rocky ridgetops. Turkey vultures glide more than they flap, easily tilting their wings from side to side to catch every stray breeze. The tail is relatively long, extending past the feet when the turkey vulture is in the air.
“Cathartes” as a genus name is related to our English word “cathartic,” or “purifying”; “aura” is Latin for “breeze.” A scientific name roughly translating as “purifying breeze” is a good reminder of the critical role vultures play as important scavengers cleaning our environment of carrion. Indeed, scientists believe that vultures worldwide may negate millions of metric tons of greenhouse gases that otherwise would be emitted by decaying animals.
A pair of turkey vultures tend their nest in an abandoned barn. Photo: Courtesy of Judy Gallagher
The black vulture (Coragyps atratus) is a much smaller bird, only a little larger than a crow or raven, with a stub of a tail and short black wings. Its distinguishing feature is bright white wingtips that flash on and off when it flaps — an avian Morse code of sorts. And it flaps (often laboriously) more than it glides; the shorter wings can’t sustain the long, effortless soaring of turkey vultures. Black vultures’ heads are also featherless, but with the grayish-black skin. The derivation of their scientific name is less poetic: “Coragyps” translates from ancient Greek as “raven-vulture,” “cora-” meaning “raven” and “-gyps” meaning “vulture.” “Clothed in black” is the translation of the Latin ”atratus.”
The common name “vulture,” meanwhile, is a direct lift from the Latin “vulturus,” or “tearer,” a reference to both vulture species’ ability to rip into dead animals ranging in size from squirrels to cattle. Those featherless heads and long necks allow them to plunge their heads deep into a rotting carcass without getting their feathers slimed. Just don’t call them buzzards — that’s a term specifically reserved for some large European hawks.
Both turkey and black vultures have powerful stomach acids that digest decaying meat and protect the birds from disease and parasites often found in rotting flesh. When disturbed, adults and chicks can projectile vomit so forcefully it would put Linda Blair to shame. Our vultures typically defecate on their legs in the nest or at a roost; the same powerful acids in their watery poop keep their legs clean from disease microorganisms, while also keeping the birds cool as the liquid evaporates in the hot summer sun.
Unlike most other birds, vultures lack a syrinx, or voicebox: no melodious trilling or raucous screeching from these raptors. At best, you’ll hear them grunt or hiss near the nest or when disputing rights over a promising carcass.
The white wingtips of black vultures look like signal lights flashing on and off when the bird flaps its wings. Photo: Courtesy of Francisco Dubon/Macaulay Library
Here’s where much of the commonality between these cousins ends. In fact, there’s always a game of one-upmanship going on between our resident vultures.
Turkey vultures have an incredibly well-developed sense of smell, a faculty usually absent in the avian kingdom. They soar lower to the ground than black vultures, skirting the tops of trees and skimming over fields hoping to catch a whiff of ethyl mercaptan, a gas that the vulture can detect in quantities as little as parts per trillion. Ethyl mercaptan is one of the gases given off by dead bodies; turkey vultures can smell this odor of decay even from shallowly buried corpses or dead animals hidden in heavy shrubbery or dense forests.
Scientists in the 1950s discovered the ethyl mercaptan connection by accident when they noticed turkey vultures gathered around leaky natural gas lines. It turns out that ethyl mercaptan used to be added to natural gas, as its distinctive smell of cooked cabbage would alert homeowners to any potentially fatal leaks — and attract turkey vultures.
Black vultures, by contrast, have almost no sense of smell but have even better eyesight than their red-headed cousins. They soar at great heights and spot dead or dying animals — or notice a turkey vulture miles away, homing in on a carcass otherwise obscured from view. And even though they are smaller, black vultures are the more aggressive of the two, regularly pushing turkey vultures off their odorous finds and claiming the putrefying prize.
Both vulture species are semi-migratory here. They’re found as far north as Canada and as far south as the tip of South America. As recently as the late 20th century, vultures were a rare sight in the DMV in fall and winter, as the weather turned colder. Now, however, many vultures forego migration and remain here throughout the year. Why the change?
Blame it on the deer.
Vulture culture today is directly tied to the explosion of the deer population in the Eastern states. In fall and winter, when carrion used to be scarce, the scavengers now find a year-round larder of road-killed deer rotting on local highways, back roads and even suburban streets.
Baby vultures may look soft and cuddly, but they can still projectile vomit noxious stomach acids — and rotting meat — when disturbed. Photo: Courtesy of Sarah Caldecott
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Rick Borchelt is a local naturalist and science writer who writes and teaches about natural history, gardening and the environment. Reach him with questions about this column at rborchelt@gmail.com.