Wednesday, April 16, 2014

The Return of the Turkey Vulture

Turkey Vulture of over florida (Wiki Commons)The very rapid loss of the snow pack that covered our region has created flooding concerns, curtailed, or completely ended, back country skiing for another year and has greatly improved foraging conditions for our ground feeding birds. Among the avian summer residents that benefit from periods of unseasonably warm weather, and the accompanying loss of snow, is a bird renowned for its scavenging talents.

Over eons of time, the turkey vulture has evolved various features to locate and capitalize on recently thawed carcasses of animals that were unable to survive the winter, and has become one of the most effective and visible scavengers in the Park.

The turkey vulture is one of the Adirondack’s largest birds, as this dark colored creature has a body that averages two to two and a half feet in length and supports a wing span of 5 to 6 feet. When seen from a distance riding air currents, the vulture can be easily distinguished from a hawk, eagle or osprey by its seemingly unstable soaring style. By angling its wings slightly upward, rather than directly in line with its body, the vulture is prone to rock from side to side as it moves through the air. Scientists that have analyzed the vulture’s flight style have determined that this wing configuration provides this bird with slightly more lift while reducing the amount of effort expended to stay aloft. As a result, the turkey vulture is better able to ride thermals and updrafts from wind being deflected by a hillside than our raptors. The straight wing profile of diurnal birds of prey helps them better maintain stability when in the air, which is of great benefit to any creature that relies entirely on eyesight to locate potential victims below.

While the turkey vulture occasionally uses vision to find a meal, this bird depends primarily on its exceptionally well developed sense of smell to find decaying masses of animal flesh. Yet, unlike a coyote or fox, which possesses a sense of smell that encompasses a wide range of odors, the vulture has an ability to detect only specific fragrances, particularly those originating from rotting animal matter. This allows a vulture to home in on the thawing carcass of a creature that perished during winter and is now beginning to putrefy.

Although the turkey vulture is commonly associated with warmer climates, this bird is able to tolerate the brief periods of cold weather that come to the North Country in mid April after this bird returns to our region. The very dark color of its plumage enables the vulture to effectively absorb sunlight to help maintain a favorable internal temperature. At night, the vulture is known to lower its core temperature by as much as 10 degrees to help conserve body heat. In the morning, a vulture frequently stands with its wings outstretched, and its back toward the sun in an attempt to elevate it body temperature back to normal.

The featherless head of a turkey vulture, while allowing some body heat to escape from its system, does limit the impact of bacteria and other harmful pathogens from lingering on its skin. As this bird rips apart chunks of decaying flesh from the remains of a dead creature, like a deer, it frequently gets droplets of blood, body fluids and liquefied tissues splattered on its face and head. Since the skin covering this section of its body is smooth and without any feathers, this decaying matter, that is laden with bacteria, is more easily dislodged when the bird shakes its head. Also, when the vulture basks in the sun, any foreign material that gets splashed on its head when it feeds will quickly dry and can be more easily rubbed off.

Like other animals that feed on carrion, the vulture has a digestive system able to treat matter, awash in harmful bacteria, without any ill effects. The ability of this bird to consume dead matter is considered by naturalists to be better than any other type of scavenger in the region. Even though a bear, coyote, fox and numerous other meat eaters will dine on dead meat should they encounter a recently deceased corpse in their travels, the vulture is known to feast on items past the point in the decomposition process that would invite any of these other scavengers to partaking in the lifeless victim.

Should a vulture be approached by another animal as it feeds, or when it is roosting in a tree, it can defend itself by regurgitating a portion of its stomach contents in the direction of the intruder. While matter in an advanced state of decay has a repulsive smell, the stench that results after sitting in the stomach of a vulture for a period of time makes it far more repulsive. While the fragrance of a skunk is bad, the smell of the vomit thrown out by an upset vulture is said to be even more sickening.

The strong southerly winds that our region recently experienced was helpful in the return of numerous avian summer residents to the Park. Among them is the turkey vulture, which is now scouring fields, open woodlands, and hillsides for the remains of thawing creatures that perished during this past Adirondack winter.

Photo: Turkey Vulture in flight over Florida (Wiki Commons).

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Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

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