By Katie Koerten Gazette Contributing Writer
With their bald red heads and carrion-eating ways, turkey vultures may at first glance lack the splendor of some of our other soaring birds. They may not carry the same symbolic importance of say, a bald eagle. They may not seem to have an exceptional skill, like the speedy peregrine falcon. But look a little closer and you will see that turkey vultures are just as impressive as more “charismatic“ birds.
According to Massachusetts Audubon’s State of the Birds report published in fall 2011, turkey vultures topped the list for greatest population increase of any bird found in the Commonwealth between 1964 and 2008. Indeed, turkey vultures are a common sight in just about any habitat; they can be found in southern Canada, the entire continental United States and Mexico. Their scientific name, Cathartes aura, provides a clue to their place in the ecosystem. Cathartes comes from the Greek word meaning “purify”—and purify they do as they scavenge the landscape, eating carrion. A turkey vulture’s diet consists entirely of the remains of dead animals—the fresher the better.
Cartoon renderings of vultures circling overhead, eagerly waiting as a dying person or animal stumbles through the desert, are not quite accurate representations of this bird’s behavior. While turkey vultures do use the sense of sight to detect carrion, they also rely heavily on their sense of smell. After an animal has died, a gas called methyl mercaptan is emitted, attracting vultures. This chemical compound is found in the tissues of humans, animals and plants. It is the same smell that many people notice in their urine after they eat asparagus, and it is also added to otherwise odorless natural gas so that leaks in pipelines can be detected. In fact, turkey vultures have been found circling gas pipelines for this reason.
This ability is one way in which turkey vultures stand out; they are among very few birds that can smell at all. One look at their nares, or nostrils, indicates the heightened use of the olfactory sense. Unlike most birds’ nares, turkey vultures have a prominent opening through which you can see completely. Even the black vulture, which is the other vulture species found in western Massachusetts, cannot smell. Rather, it follows the turkey vulture to carrion, or uses sight alone.
Besides playing a vital role as recyclers of carrion, turkey vultures have a number of fascinating adaptations that aid in their survival. That bald red head actually serves to keep a vulture clean and disease-free as it plunges its head into a carcass for a feast. A bald head is easier to keep clean, which means less potential for bacterial infection. The same goes for their featherless feet and legs, which also run the risk of coming into contact with bacteria from the carcass. A further cleansing method of the turkey vulture may seem counter-intuitive to us at first: defecating on their own legs. This actually serves a very practical purpose: The uric acid content of turkey vulture feces is so high that it serves as an antibacterial leg-sanitizer. It also serves to cool off the body in hot weather.
Turkey vultures also possess an unusual defense mechanism against predators. When nervous or agitated, members of this species regurgitate their last meal. This unique response to danger is effective in repelling any predator with a nose: You can imagine that the combination of a turkey vulture’s diet and vomit can produce quite a smell. (As someone who has personally experienced this odor, I assure you that you would not hang around either.)
Be on the lookout for turkey vultures in greater numbers in the coming weeks as they return from their southerly migration areas. Easily distinguishable by their 6-foot wingspan and soaring flight pattern, their V- shaped bodies rock from side to side as they glide through the air. Still not sure if it’s a turkey vulture or a hawk? Look at the underside of the wings. While the red head is hard to see in flight, their two-toned wings are distinctly black at the leading edges, with silvery-gray feathers on the bottom edges. The feathers at their wing-tips are separate and fingerlike. While some of the details of their natural history may seem disgusting to human sensibilities, these gentle creatures are a crucial part of the clean-up of our ecosystems and the all-important recycling of nutrients. Thanks, turkey vultures!
Katie Koerten is an environmental educator and coordinator of child and family programs at the Hitchcock Center for the Environment.
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