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Vulture 101

March 20, 2011 at 8:03 p.m.
Updated March 19, 2011 at 10:20 p.m.

A turkey vulture circles in the sky, rising on thermals.

BY JUDIE FARNSWORTH

Once upon a time, long ago, the first English colonists arrived on our shores. They looked up and saw a large black bird circling. "Yoiks, it's a buzzard."

Wrong, but who knew?

In England, there are no vultures. Buzzard is the proper term for hawks, similar to our red-tail. So buzzard it was.

There are 15 species of old world vultures from Europe, Africa and Asia and seven species of new world vultures from Canada to southern South America. We see turkey vultures and black vultures. They are part of the family Cathartidae (purifier).

Their grim reputation belies their importance. It's estimated that one vulture may eat 110 pounds of carrion a year, eliminating many disease carrying viruses. Their stomach acids are extremely corrosive. They safely digest carcasses infected with botulinum toxin, hog cholera and anthrax bacteria that would be lethal to other scavengers.

Vultures are well adapted to survive their lifestyles. Their bald heads are perfect, considering their eating habits. Head feathers would be fouled and harbor bacteria, but with just a little fuzz, anything that sticks is readily baked off in the sun.

Large, see-through nostrils let a quick sneeze eject bothersome clogs.

After eating, vultures often stand with spread wings in the horaltic pose to bake off bacteria, dry the wings or warm the body.

Vulture feet are weak and chicken-like. They're not suited for carrying, but for stepping on and holding a meal in place, which means more contact with bacteria.

In addition to baking germs off, they urinate straight down their legs. The uric acid kills bacteria and cools the legs and feet.

Turkey vultures are one of the only birds in North America with a sense of smell. They also have good eyesight.

Black vultures hunt primarily by sight and often follow turkey vultures to a carcass.

A group of vultures may remain aloft until enough have arrived to readily dispose of a particularly large carcass.

If defense becomes necessary, vultures will projectile vomit the contents of their stomach and crop - and their aim is good. Consider what they've eaten and the corrosive nature of their digestive juices - it works.

Turkey vultures are champions of energy-efficient soaring. A circling group is called a kettle. They locate rising warm air pockets or thermals. Holding their wings motionless, they let the thermals carry them in upward circles.

At the top, they stream down at speeds near 60 miles per hour before rising on another. They may glide for hours at a time, flying with wings in a V-shape or dihedral.

Black vultures have a more horizontal posture and flap more. Circling vultures don't always indicate a dead animal. They may be gaining altitude before a journey, searching for food - or just enjoying themselves.

Although vultures aloft are superstars, takeoffs are laborious, making them frequent victims of cars strikes.

Black vultures have one mate at a time. They're more aggressive and have been known to kill prey.

Turkey vultures are non-aggressive, quite gentle and mate for life.

They may not give you the warm fuzzies, but they're fascinating. Take the time to watch - from a distance.

Judie Farnsworth is a long time volunteer at the Texas Zoo specializing in educational programs.

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