Why birds circle in the air

If you ever drive on the highways, you’ll see at one time or another, big dark birds circling high on the air thermals. They are probably Turkey Vultures, Cathartes aura.

Feeding mainly on dead animals, vultures aren’t common backyard birds. But last weekend I saw one glide low right over my sister’s backyard. She lives on a river and the bird was probably scouting for washed up dead fish.

This big brownish black bird can have a wingspan up to six feet and was recognized easily not only by its large wingspan but also by its tiny, red, bald head. Male and female turkey vultures are identical in plumage and in coloration, although the female is slightly larger. Immature birds (under one year) have black beaks and heads. As the bird matures the beak gradually turns white and the head red.

Turkey vultures frequently circle and gain altitude on pockets of rising warm air, or thermals. They can soar for hours without flapping their wings. When they reach the top of the thermal, they glide across the sky at speeds up to 60 miles per hour and can cover many miles going from thermal to thermal without ever needing to flap.

The Turkey Vulture soars above the ground for much of the day, searching for food with its excellent eyesight and highly developed sense of smell.

Once only a southern US bird, by the 1960's they had extended their breeding range into Michigan. The popular theory is that the interstate highway system increased the availability of food in the form of roadkill.

 

Related Articles:

• Impressive Wake of Turkey Vultures http://goo.gl/DYddr
• Turkey Vulture are one bird that makes a ground nest in Michigan http://goo.gl/6dAek
• Why do vultures circle dead stuff? http://goo.gl/nD9qe
• Turkey Vulture facts, maps, and statistics http://vulturesociety.homestead.com/TVFacts.html