Big Birds #2: Turkey Vultures

April 2016 

by Linda Martinson 

A fairly common occurrence while driving along our winding mountain roads is to suddenly come upon turkey vultures gorging on road kill. They hop around a little, and just as you think you’re going to hit them, they take slow, ungainly, wing-flapping flight. We are most likely to see eastern turkey vultures, since they are year-round residents in the South, unlike western turkey vultures that migrate in the winter as far as South America. Its common name comes from its resemblance in head and feathers to our other local big bird, the wild turkey, and “vulture” comes from the Latin word for “tearer,” a reference to how it feeds.

Turkey vultures are unusual birds, scavengers and sanitary workers, that primarily eat only freshly killed carrion, rarely killing their own prey. They fill a critical ecological niche by reducing the spread of the bacteria from decaying carcasses. Their scientific name is Cathartes aura which is Latin for “cleansing breeze.” It is derived from the Greek word, cathartes, which means “purifier,” an apt name because, although vultures consume large amounts of toxic bacteria, they have none in their feces and do not spread diseases. 

All vultures have a remarkable adaptation to deadly microbes, and they can digest what other animals would die from eating. They have enzymes, digestive acids, and microorganisms in their stomachs that destroy bacteria and viruses, even from salmonella, anthrax, cholera, and botulism. Their waste is therefore a uric acid disinfectant, and they “sanitize” themselves and the area around them by defecating and urinating on themselves — especially on their legs. This is a rather messy and smelly adaptation, but highly effective.

Turkey vultures are big birds, about 2 feet long, weighing up to 5.5 pounds, with a wingspan of up to 6 feet. Male and female turkey vultures are identical in plumage and coloration, but the females are slightly larger. They have excellent eyesight and, rare in birds, a well developed sense of smell. They are one of the few birds with perforated nostrils, the better to detect the gases associated with decaying flesh. In a serendipitous coincidence, the chemical mercaptan is one of these gases and it is added to natural gas, which is otherwise odorless, in order to detect pipeline leaks. Years ago, pipeline workers realized that an excellent method to detect pipeline leaks is to watch where turkey vultures are congregating around pipeline locations.

  Photo credit: Wikipedia

They may may be ungainly on the ground, but turkey vultures are glorious in flight, soaring continuously without flapping up to four miles high on thermals, upward currents of warm rising air, and gliding for miles on air turbulence, horizontal air currents that bounce off barriers such as the edges of a forest. Apparently, they use their excellent eyesight to locate possible sites with carrion, and then they glide down closer to use their sense of smell to detect the exact location. Turkey vultures mate for life, and they are very social birds, roosting in large groups and soaring together in the air playing tag, follow the leader, and speed soaring games. When they find a large source of food, they sometimes will alert other flocks to join them and wait until they are all together to descend. They are slow breeders, hatching only one or two chicks a year, but they live up to 40 years. 

Photo credit here and below: James Poling, Certified Blue Ridge Naturalist

Near sunset, turkey vultures congregate to roost in communal areas with tall trees or manmade structures such as radio towers, often using the same location for generations. Many roost locations have been identified as being in constant use for over a hundred years. Some researchers hypothesize that the birds use these roosting sites as information centers to somehow communicate information about food locations. They don’t build nests, laying their eggs in protected rock crevices and overhangs near the roosting site. Turkey vultures don’t have a voice box like most other birds, so they can communicate only with grunts and hisses.

In the mornings, turkey vultures can be seen standing on tree limbs with their wings outstretched to the sunshine. The sun warms the air in their long hollow bones and makes it easier for them to fly. They begin popping up in the air for a few hundred feet to test the conditions, returning to their roosts if it isn’t time for optimal flying. When the birds are ready to fly, off they go to soar high above the ground looking for carrion to clean up. A roosting group of vultures is called a venue, but a soaring flock of vultures is called a kettle. Watch for kettles in the area, especially during the spring and summer — it is an exciting sight — and send them a little thank you for making our corner of the world cleaner, safer, and more interesting.