Missouri's Vultures

The sight of 23 turkey vultures perched on our barn roof with their 6-foot wings extended sure grabbed our attention the first time we saw them. No matter how much you know about vultures or how much you appreciate their role in nature, there will be a brief moment of alarm when you wonder if they know something you don't. Now, observing vultures throughout the day has become a welcome diversion to our daily chores.

With their small, bald, wrinkled, red heads, hunched shoulders, and large, dark bodies, vultures look like something from a grade "B" horror movie, especially when seen through the morning fog. In film and art, they are a universal symbol of dread and desolation.

Like Grim Reapers, the vultures sit in absolute silence. Lacking a syrinx, or voice box, they cannot sing. If close enough, you might overhear an occasional hiss or groan as they communicate with one another, but they will usually not allow you that close.

Often called "buzzards," New World vultures are actually related to storks and flamingoes. Of the seven species of New World vultures, three are native to the United States--the turkey vulture (Cathartes aura), the black vulture (Coragyps atratus) and the endangered California condor (Gymnogyps californianus). Only the first two are found in Missouri.

The turkey vulture is a common summer resident across Missouri. Black vultures are mostly in the southernmost counties, but they have been known to migrate as far north as mid-Missouri in the summer. Both species are limited to the state's southernmost counties during the winter.

These two species are distinguished by the color of their heads and by the length of their tails, among other features. The adult turkey vulture's head is red, and the black vulture's head is black. The turkey vulture's tail extends well beyond the feet in flight, while the black vulture's feet extend nearly to the end of the tail. Both species are federally and state protected.

Our vultures' day begins between 7 and 8 a.m. Alighting on various fence posts and the roof of the barn, they squat on their weak legs, maintaining space between one another by subtle and not-so-subtle warnings.

Their featherless heads and legs, which keep them cool on hot summer days, leave them cold and damp from night air. Once on the barn roof, the vultures move about slowly, if at all. Finally one and then another spread their dusky black wings, turn their backs or faces to the sun and get down to some serious sunbathing.

An hour or so later--around 9 a.m. in mid-summer-- their body temperatures rise back to normal, and they begin to leave their morning perch. Alternately flapping and soaring higher and higher in ever widening circles, they rise on thermal air currents from the warming earth.

They soar like gliders, gracefully dipping this way and that with their wings outstretched in a horizontal V, and the feathers at their wing tips spread like the fingers of ballerinas. Using updrafts from the surrounding hills, they rise ever higher and ride the wind out of the valley. One soars away southward, quickly becoming a small black dot high in the distant sky. Four drift slowly eastward. Nine have disappeared above the white oaks above the house to the north. Others have left unnoticed. Their day has begun in earnest.

Although up to 50 percent of a turkey vulture's diet may consist of grass, leaves, seeds and other vegetable matter, turkey vultures prefer dead animals. While all vultures have keen eyesight, turkey vultures also have a keen sense of smell, helping them find the carcasses of animals concealed under tall grasses and forest canopies.

A turkey vulture's weak talons and beak won't allow it to dine on just any dead animal. The carcass needs to be aged a bit. Being the connoisseurs of carrion that they are, they can actually determine the age of a carcass by its smell while still in the air. Movie scenes of vultures in the old west circling prospective prey that is still moving--however slowly--is the stuff of fiction. Those vultures would have a long wait.

By comparison, black vultures have a weaker sense of smell, but they make up for it with an attitude. When food is scarce, they are content to let turkey vultures do the looking. When the turkey vultures find a suitable carcass, the black vultures move in and, like schoolyard bullies, go to the head of the line.

Whether first or last in line, both vultures are particularly well designed for eating carrion that has been properly aged. Their featherless heads, for example, are particularly well suited for delving into ripened carcasses.

Their digestive systems are also specially adapted for consuming rotting meat. Vultures sterilize their food in the process of digesting it, possibly killing viruses as well as bacteria. This protects the vultures and reduces the spread of disease from the carcasses they consume. After digesting a meal, a vulture may excrete the waste onto its legs, cooling and decontaminating them and its talons at the same time. It's an odd sort of tidiness.

Vultures also occasionally vigorously vomit out their stomach contents. This strategy, which does not endear them to human caretakers, may aid vultures by lightening their weight for a quick getaway.

Vultures have also been characterized as "gentle, inquisitive and very intelligent," by at least one caretaker of captive vultures. They spend only a portion of their time looking for, eating, digesting and regurgitating food. Caretakers report that vultures often prefer the company of certain staff, sometimes following them from room to room. They also report that the vultures like to untie people's shoes and enjoy some toys, particularly hollow objects into which they can stick their heads.

In midsummer, the vultures that live in my valley start returning by 6 to 7 p.m. They arrive singly or in small groups and light on one of the prominent dead trees across the creek, and in the canopies of the trees to either side. They spend the next couple of hours preening. Sometimes, for no apparent reason, they take flight again to sail around the valley a few times before returning to the roost.

The number of vultures at the roost varies each evening, suggesting that some may remain where they have been hunting during the day. By midsummer, there seems to be fewer of them. Perhaps some pairs have dispersed to raise their young.

Vultures do not build nests in trees. A female lays one to three eggs in a log, stump, cave entrance or, occasionally, in an old barn or abandoned house. The pair take turns sitting on the eggs and, once the chicks have hatched, share the task of feeding the young. By late August, having completed their nesting activity, the pair rejoins the others at a roost.

One study of black vultures suggests that mates and closely related individuals use the same roost site on the same night. The researchers speculated that there might be significant advantages to membership in such associations, particularly in contests over food. It's also possible the communal roosts benefit vultures by allowing them to follow others to known food sources.

Our turkey vultures usually leave their roost around 8 p.m. They drop out of the trees one by one, coast over the creek or occasionally over the field to a group of tall sycamores about 1,000 feet upstream. They disappear into the thick canopy of the trees and settle in for the evening.

Observing this local roost of vultures and their activities in the valley have become a part of the rich tapestry that is our life on the creek. Their departure from the valley early in the day signals that the morning is getting away from us. Their movement to their roost just before twilight tells us it is time to put away our gardening tools and head for the house. We miss their lazy circling in our skies during the winter, and we eagerly look for their arrival every spring.

ENJOY VULTURE VENTURE

Each winter one of the largest, if not the largest, winter roosting site in Missouri is open for viewing by the public during Vulture Venture at the Department of Conservation's Shepherd of the Hills Conservation Center at Table Rock Lake. You can sometimes see up to 800 black and turkey vultures soaring above the nearby bluffs over the lake or sitting in their roost, which covers nearly an acre. Naturalists are on hand to answer questions. A program on vultures is offered every hour, and you can meet a live vulture "nose to beak."

Vulture Venture 2004 will take place Feb. 28, from noon to 6 p.m. The Shepherd of the Hills Conservation Center is located about 6 miles south of Branson on Highway 165, at Table Rock Dam. For information, call (417) 334-4865.