Illinois Natural History Survey - University of Illinois

Black Vulture

 

Susan Post

 

The Black Vulture is a large, broad-winged, soaring scavenger, most abundant in the southeastern United States. In Illinois it can usually be found year-round in extreme southern Illinois. The birds’ requirements are simple—a steady supply of carrion and sites for nesting and roosting. Its scientific name, Coragyps atratus, is a combination of Greek and Latin. The genus name comes from the combination of two Greek words, korax (raven) and gyps (vulture), while the species name, atratus (clothed in black), is Latin.

black vulture

Black Vultures are about 25 inches in length and have  57-inch wingspans. Their tails are short and squared off. The birds have been described as looking like “shabby undertakers.”  They are black overall with gray, featherless heads and necks. Their naked heads and necks prevent the fouling of their feathers while the birds feed on decaying carcasses and the bald heads may also be an adaptation to help the birds regulate body temperature. They have dark, meat-tearing beaks and thick gray legs. Their feet are adapted for walking on the ground and, in contrast to their flight, their movement on the ground is not graceful. To walk, they slightly spread their wings, take a long step with one foot then put the other foot down, so that the birds give the impression of hopping.

Their wings are black, except for a few outer flight feathers (primaries), which are white. When the wing is extended these primaries appear as white patches near the outer edges of the wings.  Black Vultures are silent birds as they lack a syrinx, the vocal organ of birds. Hissing, grunting, and blowing are the extent of their vocabulary.

Black Vultures spend most of their days in flight searching for carcasses. They usually feed on roadkill, and will visit farms, ranches, land fills, and shorelines;  any areas where carrion can be found. Live prey can be taken and there are records of them feeding on baby turtles, nestling herons, and even newborn calves. Unlike their close relative the Turkey Vulture, Black Vultures do not have a well-developed sense of smell so their foraging strategy depends on keeping other foragers such as the Turkey Vulture in view. They will follow other birds and soon large feeding aggregations will form. Black Vultures will even dominate Turkey Vultures at a carcass.

            Once food is located, the birds use their strong beaks to rip the meat off a carcass while holding it down with their feet. To reach the internal organs they insert their heads and necks entirely into the carcass. While they prefer fresh dead, they will eat meat in various stages of putrefaction. There is something in the birds’ gut that provides resistance to microbes and toxins found in decaying flesh. Thus the belief that vultures spread anthrax is false. Due to the uncertainty of their next meal, these birds can rapidly ingest large quantities of food and then go for days without feeding.

            Black Vultures form long-term pair bonds after a courtship ritual. In 1840 Audubon described this ritual as, “the gesticulations and parade of the males are extremely ludicrous. They first strut about somewhat in the manner of the Turkey Cock, then open their wings, and approach the female, lower their head, its wrinkled skin becoming loosened, so as entirely to cover the bill, and emit a puffing sound, which is by no means musical.”  Black Vultures are solitary nesters using dark caves, deep crevices in cliffs, hollow trees, or abandoned buildings to lay their eggs (usually two). No nest is made. Once the eggs hatch, the adults will feed the young regurgitated food from their crops. The chicks fledge at 8 to 13 weeks but may still associate with the parents for several more months.

            Black Vultures are not birds of prey. Their claws are weak, they do not catch what they eat, and their beaks are not strong enough to rip fresh meat. Instead, vultures are in the same order as storks and herons. Like members of this group, vultures practice urohydrosis, where they squirt liquid excrement onto their legs for an evaporative cooling effect.

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