Turkey Vultures Essay Research Paper Turkey VulturesVultures

Turkey Vultures Essay, Research Paper

Turkey Vultures

Vultures are large birds of prey closely related to hawks and eagles.

They are divided into New World vultures and Old World vultures, both belonging

to the order Falconiformes. The New World vultures, in the family Cathartidae,

consist of seven species in five genera. Among the New World vultures include

the Cathartes aura, also known as the Turkey Vulture.

Scientists say that turkey vultures are shy, inoffensive birds. Some

researchers have discovered that the bird is very helpful to the environment.

Its habit of cleaning up decaying and diseased carcasses makes it a sanitary

engineer par excellence, while its keen sense of smell has been pressed into

service to find wasteful and dangerous gas leaks. And the vulture?s unique

knack for conserving energy has intrigued scientists for years.

Although the turkey vulture has a large, turkeylike body and sporty red

head, it is not even distantly related to the turkey. Instead, turkey vultures-

along with their cousins in the United States, the black vulture of the South

and East, and the nearly extinct California condor-belong to a group of raptors

called New World vultures. Chromosome analysis shows that the New World

vultures are actually more closely related to storks than to the vultures of

Europe, Asia, and Africa.

Turkey vultures are remarkably successful birds. They range everywhere

from parts of Canada and much of the United States to South America. At home in

deserts, prairies and woodlands, they have even settled close to people in a

number of urban and suburban areas.

Observed in flight, the turkey vulture appears black with the underside

of its wings grayish or silvery, giving the birds a two-toned appearance. They

characteristically hold their wings in a slight V, or dihedral, thus aiding

identification. On rare occasions, they hold their wings flat and eagle-like

which, if seen at a great distance, may cause the birds to resemble eagles. In

flight, the turkey vulture holds it?s naked head, crimson-red as adults and

grayish-black as immatures, downward in contrast to eagles, which hold their

heads forward.

The tail of the turkey vulture extends far beyond the rear edge of its

wings. They typically rock or tilt from side to side while gliding or soaring

on updrafts or circling overhead. Their occasional wingbeats are powerful and

labored. Turkey vultures are large birds with wingspreads of about six feet.

Their wings are long, moderatly wide, and have strongly slotted tips. Typically,

the wings are held slightly above a horizontal plane when the bird is aloft.

This forms a characteristic dihedral which is very useful in making correct

field identification. Although turkey vultures use thermals, they are more

dependant upon updrafts when migrating along mountains. The birds use the air

currents skillfully and seldom exert much energy by flapping their wings.

Much of the credit for the bird?s success, scientists say, belongs to

its efficient use of energy. Turkey vultures are marvels of energy conservation.

It seems a turkey vulture?s whole life is spent trying to conserve every little

calorie it gets. If there?s some small way it can save burning its own body fat

and tissue, it will. Like an energy-conscious homeowner, a vulture turns down

its thermostat at night. During the night, a turkey vulture?s body temperature

drops a few degrees. The result is a savings in the vulture?s energy bank. To

warm up again in the morning without burning much fuel, the prehistoric-looking

bird spreads its wings and soaks up all the sun it can.

Another trick performed by the turkey vulture is a behavior called

urohidrosis. Like all birds, the turkey vulture has no sweat glands. To cool

itself during hot spells, it frequently defecates on its own legs. The slurry

of white uric acid in the feces contains mositure that cools by evaporating.

The behavior, shared by other vultures and storks, is more efficient that

sweating since it requires no boost in metabolism.

The turkey vulture?s most basic ploy for saving energy is simply staying

put. If the weather is bad for flying, they can and will sit at their roost for

days. Since their metabolism is low compared to many other birds, fasting seems

to bother them little, if at all. This ability to go without food comes in

handy for another reason. The animal?s food supply is extremely unpredictable.

They don?t know where their next meal is coming from.

The birds are well-equipped to get that next meal though. Compared with

the heavier, chunkier black vultures, turkey vultures have light bodies and long,

broad wings which provide excellent lift. They don?t use or lose a lot of

energy landing and taking off, so they?re able to exploit small food items

efficiently. As a result, you?ll often see a turkey vulture at a road-killed

mouse, something the black vulture wouldn?t consider doing.

Turkey vultures are also masters of effortless flight. By riding

thermals, they can search for carcasses over dozens of square miles with only a

few flaps of their wings. From a vulture?s point of view, finding a carcass is

a race against time. Not only do vultures have to beat mammalian scavengers,

already on the ground ready to follow a scent trail to the prize, but they also

have to find the body before insects render it an inedible, maggot-ridden soup.

The turkey vulture?s total dependence on its sense of smell to find food

in the forest can be easily demonstrated by putting out carcasses, some left

uncovered and some hidden completely by a pile of leaves. The birds find the

hidden carcasses just as quickly as those in the open. Turkey vultures hunt by

flying just above the level of the tree canopy, sniffing the air all the time.

As soon as they get a whiff of rotting meat, they start to circle to determine

where the aroma is strongest. They then fly down into the forest, following the

scent trail from tree to tree, until they are led to their reward on the forest

floor. Because an airborne bird on the scent is usually within sight of many

others that are quick to follow, good numbers of vultures of various species can

congregate at a carcass within minutes.

Turkey vultures could not detect carrion less than about twelve hours

old. A carcass twenty-four hours old, however, emits a sufficient stench to

attract vultures readily. These birds have a reputation for savoring stinking,

rotting meat, but when offered a choice of relatively fresh or rotting meat,

they strongly preferred the fresh. Badly decayed meaat contains unpleasant

bacterial compounds that either impede digestion or are actively toxic.

Vultures will eat rotten meat if they are extremely hungry, but if they are not

short of food, they will give bad meat a miss and wait for the scent of

something more palatable. Turkey vultures can tell from the smell coming

through the tree canopy how long an animal has been dead, probably because the

smells given out by the bacteria that develop in meat change with the age of the

carcass. Thus, vultures do not even bother to fly down to old carcasses as

often as they do to day-old carrion. Only turkey vultures can locate food by

smell; black and king vultures lack this ability completely.

Once the scavenging birds find something dead in the wild, another set

of unique abilities comes into play. Since decaying meat is not the most

healthful of foods, turkey vultures have evolved into veritable detoxification

plants. Not only can they eat food so rotten that it could kill most other

creatures, they benefit people and the environment by preventing the spread of

diseases. Among these is botulism, a deadly sickness caused by a bacterial

poison that attacks nerve-muscle junctions and leads to death by suffocation.

Biologists have found that turkey vultures have both botulism-resistant nervous

systems and heavy duty immune systems that ward off the bacterial toxin. In one

experiment, a scientist injected one turkey vulture with a dose of botulinus

toxin lethal enough to kill 300,000 guinea pigs. The bird never showed a moment?

s illness.

But while turkey vultures are formidable foes of bacteria, they are shy,

cautious and docile when confronted by virtually any creature larger than a

microbe. This shyness is often carried to an extreme. When the birds are

trapped and handled, they are totally docile. Being submissive is only one way

a turkey vulture acts when stressed. When frightened, they tend to regurgitate.

Whether the act is intentional or not, it provides the dual benefit of

lightening the load for a quick getaway and repelling any would-be antagonist

with the stomach content?s foul odor.

The turkey vultures? foul and sinister reputation, however, finally

seems to be changing. In fact, the infamous scavengers are actually finding

themselves appreciated by some people. Each year, for example, thousands of

people jam the town of Hinckley, Ohio, on one Sunday in March. The occasion is

called Buzzard Day. This is the day that the vultures are scheduled to drift in

from their southern wintering grounds. People from all over the area gather to

watch their beloved birds reappear.