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Turkey vultureTurkey Vulture

Order:  Falconiformes – vultures, hawks, eagles, kites, falcons

Family:  Cathartidae – New World vultures

Scientific Name:  Cathartes aura

 

DescriptionThe turkey vulture is one of North America’s largest birds of prey, with a wingspan of 5 ½ - 6 feet.  The feathers are brownish-black with slight iridescence.  The head and neck are bare, and the skin is bright red or pink.  They have a powerful, hooked beak.  In flight, they hold their wings in a slight V-angle (dihedral) with the primaries separated, and their wings appear two-toned with dark gray flight feathers looking lighter than the black wing linings.  Males and females look alike.  Juveniles have duller brown plumage, and dark gray skin on the head and neck.

 

RangeHome Range: Southern Canada, throughout the United States, Mexico, Central and South America

 

Habitat Type:  Adaptable to a wide range of habitats, including deserts, grasslands, tropical rain forests, and temperate forests

 

Reproduction:  Turkey vultures nest in shallow caves, on the ground in thick undergrowth, or in hollow tree stumps and logs.  They build little or no nest.  In North America, eggs are laid in the spring or early summer.  They lay only one clutch per season, and the typical clutch includes 2 eggs.  Most eggs are white with brown spots and splotches, with a diameter of about 2.8”.  Occasionally an egg may be pure white.  Both parents share incubation duties for 38-41 days.  The young are semi-altricial (helpless), with white down and a bare head.  The down allows the chicks to keep themselves warm from a very early age, and most parents visit the nest site for only a few minutes each day.  The chicks are fed regurgitated food from both parents.  They fledge after 70-80 days, or sometimes stay in the nest slightly longer.

 

Diet in the Wild:  Primarily carrion.  They prefer the carcasses of medium-sized mammals, but also eat insects, dung, berries and fruits, and carcasses of smaller mammals, snakes, and lizards.  In many areas, they frequent highways where they can feed on road kill.  By feeding on carcasses, they prevent the spread of disease and clean up the landscape.

 

Diet in the Zoo:  Bird of prey diet

 

General Information:  Although they are placed in an order with the eagles and other diurnal birds of prey, the New World vultures are probably more closely related to storks.  They resemble the Old World vultures not because of common ancestry, but because of convergent evolution – both groups have developed the same adaptations to excel at similar lifestyles.


When feeding at a carcass, turkey vultures first remove the eyeballs and then rip through the skin, tearing and pulling it back to expose the muscle and tissue beneath.  They are very resistant to botulism and other bacterial toxins that can accumulate in carcasses.  Other vultures are dominant over them.  Turkey vultures usually arrive at a carcass first and begin feeding, then withdraw when other species arrive.  After the other birds have left, the turkey vultures return to finish any remaining tissue.  This genus is one of only a few birds to have a highly developed sense of smell (even other vultures do not have it).  The sense of smell plays a major role in locating food, and has been used by engineers, who placed ethyl mercaptan (the odorous substance in carrion) in gas pipelines to discover leaks.  Leaks along a 42-mile long pipeline were immediately located by observing turkey vultures circling above them. 


Like other vultures, they have an enlarged crop for storing large amounts of food.  When a carcass is located, they can gorge themselves and then survive 2 weeks or more without another meal.  The bare skin on the head is easy to keep clean when feeding on carcasses, and probably also helps to prevent overheating.  South American subspecies can change the color of the skin on their heads, and seem to use the color to communicate in dominance disputes.  As another temperature-regulation mechanism, vultures defecate on their legs, a behavior that they share with the storks.  The evaporation of water in the feces cools the skin.  Like other vultures they use soaring flight, circling upwards on a thermal and then gliding down until they reach another thermal.  Soaring flight is very efficient, and allows vultures to travel long distances in search of carcasses with a very low  expenditure of energy.  They can often be seen sunning with wings outstretched, probably to warm themselves in the morning and to keep their feathers in optimum condition.  After a long period of soaring, the feathers can become bent.  The sun’s heat causes keratin complexes in the feathers to relax, so that the feathers return to their original shape.  Vultures are usually silent, but they can produce quiet hissing, rattling, and sneezing noises.

 

Conservation Status:  Turkey vultures are very widespread and abundant.  They benefit from road kills, and have recently been increasing their range northward.

Predators:  Nests are raided by foxes, raccoons, or other mammals.  Adults have few predators.

 

Resources

Birds of Prey.  1990.  I. Newton.  Fog City Press, San Francisco.  pp. 18-19.

 

Handbook of the Birds of the World, Vol. 2.  1994.  J. del Hoyo, A. Elliott, and J. Sargatal.  Lynx Edicions, Barcelona.  pp. 24-37, 39.

 

Life Histories of North American Birds of Prey, Part 1.  1961.  A.C. Bent.  Dover Publications, New York.  pp. 12-24.

 

The Sibley Guide to Birds.  2000.  D.A. Sibley.  Alfred A. Knopf, New York.  p. 107.