The Turkey Vulture

Turkey Vulture

Cathartes aura

TURKEY Vulture? – why are they called Turkey Vultures? This bird got its common name from its resemblance of the adult's bald red head (and possibly its dark plumage) to that of the male Wild Turkey. Turkey Vultures are the most common vulture in the Americas with a range that extends across much of the continental United States, into Central America, and throughout most of South America. They exist in a wide range of habitats from deserts to savannas and grasslands, to tropical and temperate forests making them a very adaptable species.

Turkey Vultures are almost entirely carrion eaters feeding on mammals from small to large, preferring those recently dead. They may also feed on plant matter, shoreline vegetation, pumpkin and other crops, live insects and other invertebrates. Turkey Vultures can often be seen along roadsides cleaning up roadkill, or near rivers or the ocean, feasting on washed-up fish, another of their favorite foods. How can one animal consume carrion without getting ill, while another would surely die?  Due to the nature of their diets, vulture excreta has a high uric acid content that acts as a sanitizer as they defecate on their own legs, killing any bacteria the birds pick up while traipsing on its food. This allows them a certain tolerance towards microbial toxins (such as botulism) and certain synthetic poisons that have been used to kill coyotes and ground squirrels.

Turkey Vultures have a keen sense of sight to locate carrion but also, unlike other birds, it has an acute sense of smell. The olfactory lobe of its brain responsible for processing smells is particularly large compared to other birds. It will often fly low to the ground to pick up the scent of ethyl mercaptan, a gas produced by the beginnings of decay in dead animals. This heightened ability to detect odors allows it to search for carrion below the forest canopy.

Seldom does this graceful and talented bird flap its wings as it soars over large areas searching for carrion. They often take advantage of rising thermals to keep them soaring. The Turkey Vulture maintains stability and lift at low altitudes by holding its wings up in a slight V-shape and teetering from side to side while flying. This side to side flying causes the gray flight feathers to appear silvery as they catch the light. The distinctive flight style, small-headed and narrow-winged silhouette, and underwing pattern make this bird easy to identify at great distances.

The Turkey Vulture has few natural predators. Its primary form of defense is vomiting. These birds do not "projectile vomit, " as many would claim. They simply cough up a lump of semi-digested meat. This foul-smelling substance deters most creatures intent on raiding a vulture nest. This lump of ’meat’ will also sting if the offending animal is close enough to get the vomit in its face or eyes. In some cases, the vulture must rid its crop of a heavy, undigested meal in order to lift off and flee from a potential predator. In this case, the regurgitated material has not yet been digested. Most predators will give up pursuit of the vulture in favor of this free edible offering.

The head of turkey vultures is perhaps the most unique characteristic, being very small in size when compared to the large body. The head and neck are red in color and lack feathers, with the exception of a thin layer of down.  The beak is relatively short, hooked, and light in color. The feathers of the adult are brownish-black, but the lower half of the wings on their ventral surface is silvery white. The feet are rather weak which are used for walking rather than grasping prey. The typical adult bird is an average 30" long with a 6 ft wingspan, and weighing 3 lb. The sexes are similar, with the female being slightly larger.

An immature bird looks quite different.  Just out of the egg, they are white with a black beak. Typically the female lays 2 eggs that are hatched after about 40 days.  Both parents take turns incubating the eggs and caring for the young for 10-11 weeks by feeding them regurgitated food. The age of the young at first flight is about 9-10 weeks.

Turkey Vultures roost in large community groups, breaking away to forage independently during the day. They are often seen standing in a spread-winged stance. This is called the "horaltic pose." The stance is believed to serve multiple functions: drying the wings, warming the body, and baking off bacteria. Though they are seen frequently, they are elusive in nature which has resulted in there being very little known about their general behavior and social organization. For example, the ability to locate food and then communicate the discovery to other individuals over fairly long-range distances accurately has yet to be fully comprehended in the scientific world. Like most other vultures, Turkey Vultures have very few vocalization capabilities. With no vocal organ, they can only utter hisses and grunts. They usually hiss when they feel threatened. Grunts are commonly heard from hungry young, and adults in courtship.

Turkey vultures return to summer feeding grounds on or near the Vernal Equinox in some parts of the country. During winter months turkey vultures migrate to warmer regions.  Here at the Phoenix Zoo, they often ’migrate’ to our Turkey Vulture exhibit.  Many guests comment that some of our collection birds have escaped their enclosure.  If you are ever confronted by a guest that is concerned about escaped Turkey Vultures, it’s always good to double check with Living Collections however, it’s more than likely the birds on the outside are wild ones looking to join their conspecifics!

Sources: http://en.wikipedia.org/wiki/Turkey_Vulture; http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Turkey_Vulture.html; http://www.peregrinefund.org/Explore_Raptors/vultures/turkevul.html                                                                             edited by Julie Deiter