Tuesday, August 3, 2010

Turkey Vultures

By Susan Thurn,
CNHM Director of Education

A dark silhouette was flying over the field, recognizable by its dark profile and v-shaped wings. It was circling, two days in a row near my home. I smiled when I recognized a turkey vulture. Was it circling for some carrion? Or riding the winds? Some may refer to this bird as ugly, but I think it is beautiful, and turkey vultures have behaviors and adaptations that make them extremely interesting.
The turkey vulture got its name from the common turkey because of the similarities to the turkey’s reddish, featherless head. This almost bald head covered with a fuzz of down serves an important purpose. The turkey vulture eats dead carrion, and must stick its head inside the carcass to reach the meat, so the lack of feathers keeps the bird clean of blood and bacteria.

The turkey vulture does not feed strictly on carrion. They will also eat plants, including shoreline vegetation and some crops. They will soar above the ground searching for their food with their sharp eyesight and very developed sense of smell. They are not aggressive, and will not feed on live prey. Sometimes we can see them along roadsides looking for roadkill.

Turkey vultures are one of the few birds that have a heightened sense of smell, and the part of their brain that processes smells is very large. This raised awareness allows them to detect odors of dead animals below the forest canopy.

Do vultures circle the air looking for carrion? Actually, turkey vultures soar on warm bubbles of air called thermals. As warm air rises, they glide in circles to conserve their energy. They also use the thermals to raise higher so they can fly longer distances. Flying in circles also serves the purpose of letting them scan for food. Vultures are easily distinguished as they maintain a v-shaped flight, teetering side to side, to keep stability at low altitudes. Flying lower to the ground in this shape allows them to pick up the scent of dead animals. This flight pattern is quite a remarkable skill in the bird world, allowing vultures to glide for up to six hours without flapping their wings, diving out of the thermals at almost 60 miles per hour.

Turkey vultures are related to storks rather than birds of prey, and so they urinate on their own legs, using evaporation of water in the waste to help them cool down. It is also believed that the urine is acidic, helping to kill bacteria they may get from stepping in their own dead food. Vultures also have weak, chicken-like feet, which allow them to step on the ground and hold their food in place, rather than like other raptors that clutch their talons and fly in the air with their prey.
There are some additional adaptations that turkey vultures have. They roost in large groups except when they forage independently. They often can be seen with their wings wide spread, called the “horaltic pose,” perhaps to dry their wings, warm their dark body in the sun, or bake off any bacteria. Although they do not have many predators, their defense is to vomit. They cough up a lump of partially digested food, and the smell deters predators, or if it gets in their eyes, stings. Sometimes, they will vomit a large amount of “meal,” which predators may choose to eat instead of pursuing the vulture.

Keep your eyes out for turkey vultures in the air nearby. They will begin migrating later in September, so will become even more visible. Who knows what you might see happen! Explore and wonder from your own back yard.

Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and new exhibit, On Lake Owen: The Art of Walter Bohl, in Cable at 13470 County Highway M or on the web at www.cablemuseum.org to learn more about exhibits and programs.

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