Saturday, August 24, 2013

Migration of turkey vultures

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. Turkey Vultures nest as far north as the southern border of Canada and as far south as Chile. Populations in Michigan and other colder areas migrate south to warmer weather in the winter.

This big brownish black bird can have a wingspan up to six feet and is 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.
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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.
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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.
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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.
 
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