Contributed by Winsor Marrett Tyler
[Published in 1937: Smithsonian Institution United States National Museum Bulletin 167 (Part 1): 12-28]
When we travel southward along the Atlantic Seaboard, soon after we cross the invisible line that separates the Transition Zone from the Upper Austral (the map shows us to be in the State of New Jersey), we begin to see from time to time dark spots high up in the sky. They seem stationary at first sight; then, as we watch, we see that they are moving, swinging often in wide circles, and when one of them comes near, we see it is a great dark bird sailing through the air. We have entered the domain of the turkey vulture, the chief avian scavenger of the United States; a big bird with long broad wings, with a keen sense of sight and of smell and, utilitarian as well as aesthetic, a plumage that does not show the dirt, and a naked head and neck like the bare arms of a butcher; a bird of prey, one of the Raptores, but one that does not inflict death, but searches and watches and waits until it comes upon the dead. Then the feast begins.
Spring.--Toward the northern limit of the bird's breeding range an increase in its numbers is noted at the approach of spring. Thus Thomas H. Jackson (1903), writing of southeastern Pennsylvania, says, "Early in April, with the advent of settled weather, they become quite numerous, and at once show an attachment for the old nesting sites, to which they seem to return for many years."
Louis B. Kalter reports a flock of 30, apparently migrants, going westward over Yellow Springs, Ohio, on March 20, 1933, at 4:30 p.m. Dr. O. L. Inman reported to him that "during part of the time they were in sight, they seemed to hold rather a loose formation, when most of them would be going in the same general direction. Then they would break and wheel about for a short time, only to reform their loose formation."
Dr. F. M. Chapman (1933) made observations at Barro Colorado Island that point to an extensive northbound migration of vultures late in February and March. Large numbers of the birds, several hundred together on one occasion, passed over the island, following the course adopted by kingbirds and barn swallows on their route northward (at this point southwest). He says: "Usually they sailed straight ahead without stopping but at times they circled, though still drifting southward."
One day they flew over the island at a height of 4,000 to 5,000 feet, and on another day, in the morning, Dr. Chapman found a number of vultures collected in trees. "These," he says, "were apparently migrating birds which had roosted over night on the island and, becalmed, were waiting for enough wind to resume their flight."
Wherever these birds were bound--a question impossible to answer definitely--Dr. Chapman's observations indicate that the turkey vulture is, to a certain extent, highly migratory and that many individuals, gathered in flocks of considerable size, make a very long journey between their winter quarters and their breeding grounds.
Nesting.--In any region, no matter how widely it may range, there is a limited number of places in which a bird as large as a turkey vulture can hide its nest. The vulture is a big bird; it must have room for its nest somewhere either inaccessible to predatory animals of where they cannot easily reach its eggs or young. There is the added danger that the odor of the food may proclaim the whereabouts of the nest after the eggs are hatched and the young birds have to be fed.
Many situations meet these requirements in some degree, notably on precipitous cliffs, of access only through the air, or in caves or hollow stumps, or in the midst of dense shrubbery where a narrow entrance limits the attack by enemies to one direction. In such locations the vulture lays its eggs on the ground, or on the bare stone of a cliff, or on the rotten chips in a hollow log with little or no attempt to make a nest.
The literature contains descriptions of many nest sites of the vulture. The following citations show a variety of ways in which the bird has solved the problem of protecting its nest. The nest site is almost always on or near the ground, but in one case Isaac E. Hess (1910) found a nest "twenty feet up in a dead stump, and [another] six feet below the surface of the ground in the hollow of a rotten stump." Manley B. Townsend (1914) notes another tree nest. He says: "At the very top [of a gigantic elm tree] there was the hollow, dead shell of the main trunk, and, in this, upon the bare decayed wood, two eggs as large as Turkey eggs." William Lloyd (1887) speaks of the birds in western Texas as "breeding in caves, but frequently on the bare edge of a bluff," and in Texas also James J. Carroll (1900) mentions them as "selecting brush-heaps, clumps of chaparral, caves in arroyo banks, and hollow trees." Dr. T. Gilbert Pearson (1919) says: "I have found the eggs of these birds on a level with the ground in the hollow snag of an old tree, the entrance to which was at the top, 14 feet above."
In the two following quotations water plays the part of the ancient moat in defending the vulture's castle. In a letter to Mr. Bent, S. A. and George M. Smith describe a nest in Orleans County, N.Y. They write: "The nest we found was located in an old decayed hollow log which had fallen from its stump many years ago, and lay rotting amid a luxuriant growth of ferns and other swamp plants. There was nearly one foot of water all around, but the two eggs were placed on a bed of dry leaves and decayed wood."
Russell M. Kempton (1927) describes a similar nest in detail thus:
The nest is in a live soft maple tree, whose trunk slants on a sixty degree angle east by north and has a southern exposure; inside dimensions of the cavity are diameter twenty-eight inches; height, forty-two inches and its bottom is about forty inches from the ground. The top of the cavity is closed by dry decayed wood. The surrounding ground is swampy and during wet seasons water stands thirty inches deep around the base of the tree.
The nest is unlined, and the eggs were deposited on clean broken up punk. . . . It was always clean (also the ground around the tree), from the time the eggs were laid until the nestlings left the nest. No offensive odors were noted during the five years of observation (except when the nestlings would regurgitate for me).
Continuing, Kempton shows the vulture's simple method of making her nest with materials near at hand.
The parent birds arrived March 18, and used the same nest to roost in during the cold wet spring. On several occasions during daylight in April, I found them in the nest standing with heads together, and they did not fly when I approached within ten feet of the tree. Visiting the nest on April 28, I watched them preparing the nest, by pulling at the dry rotten wood on the side walls of the cavity with their beaks. When a large piece came loose the female would hold it down with one foot and tear it into small bits, which she spread about on the floor, where the eggs were to be deposited. The interested male bird, was a hindrance in nest making, and every now and then the female placed her head under his breast and pushed him out of the way. Once he tumbled out of the tree. However, undaunted, he clambered back keeping his head down, so that his mate could not repeat her attack.
Mr. Kempton observed that "both birds alternately covered the eggs during incubation."
Paul G. Howes (1926), in an account of the vulture's nest in a cave in the State of New York, says: "Another point of interest to me was that there was absolutely no odor about the nest." At this time the nest contained eggs, but on a later visit he remarks: "A very offensive odor emanated from the rocky shelter now for the first time, and as we approached very quietly, the old bird bounded clumsily to the rear of the cave. . . . The young one had hatched safely, had had its first taste of carrion, as its vile odor attested."
Thomas H. Jackson (1903) reports an unusual nest site. He says: "I found a pair that had taken possession of an abandoned pig sty in the woods, which furnished them with an admirable place to set up housekeeping. Unfortunately, the smooth board floor had allowed one of their two eggs to roll away, and only one was hatched. Here they were safe from the attack of foxes, raccoons or other night prowlers."
A. L. Pickens (1927), reporting some "out-of-the-ordinary" records, includes the following on the turkey vultures.
On May 1, 1927, I was at the home of Mr. Elihu Wigington in Anderson County, S.C., and he took me to an old and neglected barn in a wood near his home to see a nest of this bird. I found the eggs, two in number, on the refuse of the stable floor, close up in a corner. About ten feet away a domestic hen was brooding on her nest in a pile of forage, the two being separated, however, by a low partition. The vulture could gain access to its nest through a small window in the stable, or through a door at some greater distance. Mr. Wigington told me that this was the third year this place had been used by the Vulture for a breeding spot.
Of the time of nesting Bendire (1892) speaks as follows: "In most of the Southern States nidification begins usually about the latter part of March, occasionally even in February; in the Middle States generally about the last week in April or the beginning of May, and in the more northern portions of its range it may be protracted till June, according to the season."
Charles E. Doe writes to us of a set of eggs he took from an old caracara's nest, 20 feet up in a lone palmetto on a Florida prairie.
Eggs.--[AUTHOR'S NOTE: The turkey vulture lays almost invariably two eggs, occasionally only one and very rarely three. I have a photograph of a nest containing four, but they were in pairs a short distance apart and were probably the product of two females. The eggs are usually elliptical-ovate or elongate-ovate in shape, but a few are ovate and rarely one is cylindrical-ovate. The shell is smooth or very finely granulated, with little or no gloss. The ground color is dull white or creamy white. The eggs are prettily marked and sometimes nearly covered with spots, blotches, and splashes of bright browns. Generally they are boldly or irregularly blotched and spotted, sometimes sparingly or finely spotted, with dark browns, such as "chestnut," "liver brown," or "chocolate" and more rarely with "russet" or "cinnamon-brown"; they are often washed with one of the above browns and may have underlying spots in shades of "Quaker drab." Very rarely one is nearly or quite immaculate.
The measurements of 52 eggs average 71.3 by 48.6 millimeters; the eggs showing the four extremes measure 83.5 by 50, 76 by 53, 62.5 by 50.5 and 71.3 by 43.7 millimeters.]
Young.--When the nature of the vulture's food is considered, it seems almost inevitable that the young birds, in their earlier days, be fed by the process of regurgitation. Thus, one of the first associations that the nestlings learn is that of the odor of decomposing animal matter with appetite and good digestion.
A. G. Lawrence, writing from Winnipeg, Manitoba, to Mr. Bent, describes the process, which he watched from a blind on the side of a cliff. "Both young rushed toward the female parent with widespread wings. The first to reach her thrust its bill well into the parent's gullet, the old bird stretching out low over the rock to facilitate the exchange of regurgitated food. The feeding process was carried on so vigorously that it resembled a tussle, both birds swaying their heads up and down and from side to side balancing themselves by raising their wings."
As these young birds "were fully grown, but unable to fly," this method of feeding may continue through the major portion of their protracted life as nestlings. Lawrence continues: "The young spent much of their time sunning themselves on the rocks outside the nesting cavity. They continually exercised their wings, spreading them out to their full extent whenever the sun shone and closing them when a cloud cut off its rays. They stood with backs to the sun, and their wings immediately responded to its warmth."
Thomas H. Jackson (1903) estimates the period of incubation as "very close to thirty days, possibly a day more or less" and "the period between hatching and flight eight or nine weeks." In the case of a nest under observation of C. J. Pennock, these periods were somewhat longer; the incubation lasted about 41 days, and at the end of 74 days the young birds "had not been away from the near proximity of the site and had not flown at all."
Dr. Pearson (1919) says: "From eight to ten weeks are passed in and about the nest before the young are able to fly." Jackson (1903) continues:
Young Turkey Vultures at a very early age display more intelligence than the young of any other raptores with which I am familiar. Their eyes are open from the first, and in less than a week they move about in their home, hiss vigorously, and show considerable alertness, but do not seem to have any fear at that age. At two weeks they show an increase in size and weight, but otherwise have changed but little in appearance. They now resent being disturbed and snap at the intruder, and as they get older become quite pugnacious, rushing at one with extended wings, uttering continually their loud hissing sound, which comes the nearest to any vocal performance I have ever heard from these birds. Their beaks are quite sharp and capable of injuring an unprotected hand.
On being approached they retire to the farthest corner of their den and there disgorge the contents of the stomach or crop.
H. Justin Roddy (1888), speaking of the nestlings as pets, says:
The young birds kept in captivity drank water freely from any vessel as a fowl drinks, but were fonder of drinking from some vessel, as a bottle, with a narrow opening partially inverted, that the liquid might flow out. This must be because it is similar to the opened bill of the parents.
They are very fond of thrusting the bill into the opening formed by the partially closed hand. I inferred from this fact the manner of feeding before I had an opportunity of observing it.
They are very fond of being caressed, or at least handled, especially so while feeding. In a few days after being placed in captivity they become fond of being handled, and soon follow persons about like dogs. They express pleasure by a low hiss; displeasure by a more forcible hiss.
Leon L. Gardner (1930), in a study of the body temperature of nestlings, states that "A young Turkey Buzzard early in its development attained the temperature normal to the species. . . . At one week of age it was 102.5 and at two weeks of age it had risen to and above the normal for the species. Thereafter there was a remarkable constancy of temperature at about 103.6 except when influenced by other factors [struggling]. The Buzzard therefore apparently stabilizes its temperature long before the appearance of feathers and while the general development of the body is still immature."
W. Bryant Tyrrell has sent us some elaborate notes based on his studies of a brood of young turkey vultures, from soon after hatching up to the flight time, and has contributed an interesting series of photographs illustrating the development of the juvenal plumage.
The nest contained eggs on April 15 and April 30, and the young were hatched but still very small and helpless when the nest was next visited, on May 21; they were probably not over three or four days old; they were unable to hold up their heads and were completely covered with white down, except on the black face. On June 4, the young were still covered with down, except that the primary quills were beginning to show, the sheaths protruding about three-quarters of an inch and tipped with down; they were now about 17 days old and about three times as large as they were on May 21. When about 37 days old, on June 24, the young were still covered with down, but "the primaries and secondaries and their coverts were about 4 inches long, and the tail feathers were about 3 inches long." On July 4, when about 47 days old, "the birds were about two-thirds grown. The wing feathers were well developed, though still growing, and the tail feathers 3 1/2 inches long. The rest of the body was still covered with down, which came off easily." When about 60 days old, on July 17, the wings appeared to be quite fully developed, the back was well feathered, and the plumage was coming in on the sides of the breast, but the neck and the remainder of the under parts were still downy. Mr. Tyrrell made his last visit to the nest on July 25, when the young birds were about 68 days old. "Both were well feathered, with down only about the breast and belly, and, in one, some still clinging to some of the feathers of the neck, looking like a ruffled collar."
Apparently the juvenal plumage is not fully assumed, or the flight stage reached, until the young vulture is well over 10 weeks old.
The juvenal plumage is much like that of the adult, but with lighter edgings on the feathers of the mantle; the plumage is said to be darker when fresh, but it fades out to dull brown, "Verona brown" to "warm sepia." The naked skin of the head and neck is blackish or livid brown, not red as in the adult; and the neck and crown of the head are scantily covered with short, dark brown, hairy down. This plumage is worn through the first winter. The annual molt of both young birds and adults begins late in winter or early in spring and continues gradually through the summer and early fall, the wings and tail being molted in September and October. The new body plumage, which appears first on the breast, neck, and back, is glossy, bluish black at first, but fades out later to dull, dark brown.]
Food.--The inability of the vulture to kill its prey has forced it to play the part of a scavenger, and the struggle for existence has driven it further. Where the bird is abundant, it cannot, like other Raptores, select its victim; it has to accept what chance presents.
When death comes to any animal, its body becomes food for the vultures. As soon as the animal can no longer move, the meal is ready, and if a vulture finds a dead body, although it be warm from the life just flown, the bird begins at once to feed. But a large animal--a horse or a cow--cannot be finished, even by a company of voracious vultures, while the body is fresh. Putrefaction works fast and overtakes the birds, and the end of the meal becomes far advanced in decomposition. Also it often happens, owing to the position of the body, or because it is submerged, or because the hide is too tough for the vulture's beak to tear, that little or none of it is accessible to the birds. Then the vultures gather about the carcass in large numbers, if it be a big one, and wait patiently near at hand until time and decay, making it soft and ripe, shall fit it to their needs. Then they descend and strip it to the bone.
Thus evolution has led the vulture in its search for food away from the other Raptores and has compelled it to develop feeding habits that it shares with few companions among birds and mammals.
The vulture shows apparently little preference in its choice of food. It is a useful bird in the Southern States, where it disposes of the dead animals about the farms, and, as Dr. Pearson (1919) says, "in many a southern city the Vultures constitute a most effective street-cleaning department, and the garbage piles on the city's dump-heaps are swept and purified by them. When the rancher of the West dresses cattle for home consumption or the market, his dusky friends in feathers gladly save him the trouble of burying the offal."
Wright and Harper (1913), writing of the Okefinokee Swamp, remark that "it is astonishing how soon the buzzards appear over a spot where an alligator has been shot, and how quickly they transform its carcass into a bare skeleton."
Florence A. Merriam (1896) reports from California that Mr. W. W. Merriam watched two of the buzzards eating skunks. They began by pulling the skin from the head and ate till they came to the scent gland, which they left on the ground."
Snakes appear to be a favorite food. Ivan R. Tompkins, in a letter to Mr. Bent, says: "I flushed two turkey buzzards from a clump of willows. On looking into the bushes to see what they were discussing, I found the partly eaten remains of a cottonmouth moccasin that had been dead some time. The head had dried instead of decomposing, and I picked it up with a forceps, and was able positively to identify it. The buzzards had eaten the meat off the back bone rather than swallowing the snake whole, as I would have expected."
R. M. Kempton (1927) says "a reptile was evidently a choice relish, because one dead snake will call fifty vultures, more or less, to the vicinity of its demise."
Dr. Pearson (1919) writes: "To a limited extent, our southern Vultures feed on living animals. Newly-born pigs are killed by them, and, in some bird colonies. . .young Herons and Ibises are often eaten." W. E. D. Scott (1892) corroborates this statement. He says that the vulture in Jamaica "is certainly not a carrion eater from choice, fresh meat being eagerly taken whenever an opportunity offers, and when sore pressed young and weakly chickens, etc., are taken up."
The birds have been known to feed on grasshoppers, and they readily eat fish. Dr. Alexander Wetmore (1920) mentions that in New Mexico "they clambered over the piles of Potamogeton and algae cast up last year and left on the shores, picking at it experimentally, pulling off the surface and digging into the interior with their bills as they would into carrion."
James Green (1927) reports a remarkable observation of finding a flock of 62 vultures, hard pressed for food, feeding on pumpkins. He says: "A few had been touched by frost, making them soft, and these had been all but pecked to shreds. But there were the marks of the buzzard's powerful beaks on the sides of the big yellow pumpkins that otherwise were sound as a dollar."
The young pigs left dead on the road by automobiles in the Southern States afford opportunities to observe the dissecting habits of the vulture. A bird sails along, doubles back, alights, and, folding its great wings, slowly approaches the pig. With head high and tail held well above the ground, it sidles about, wary and watchful lest the pig move, it seems; then reassured, it steps upon the body and, with a deft hook of its beak, extracts the eyeball and swallows it.
The vulture next nips through the skin and by tearing or pulling it back lays bare the muscles beneath. Three times I have seen vultures make their first incision over the upper part of the shoulder blade and pick out and devour the supraspinatus muscle before they touched any other part of the body, except the eye.
The vulture at its meal moves deliberately, but, like a skilled workman, surely. It is watchful of intrusion and will not tolerate the approach of other vultures while eating as small an animal as a young pig. It turns upon any vulture that comes near, but more with a remonstrance than a threat. Indeed, as we watch, we see that a solemn but strict etiquette governs the bird at its meal.
Mr. Bent once surprised a party of turkey vultures that were feeding on a lot of dead tadpoles that had become stranded by the drying up of a small pool in Florida. He has also often seen them feeding on the main highways there, where snakes, turtles, small birds, or small mammals have been killed by passing automobiles, or where fish have been thrown away by fishermen. Often, when disturbed by an approaching automobile, the vulture will pick up some such small object in its bill and fly away with it.
Behavior.--On the ground the vulture is an awkward bird, hopping clumsily, sometimes with a hitch sideways; it has a gawky walk. To get into the air it leans forward, stumbles onward with a few steps or hops, gives a push with its legs, and, with a visible effort, flops its wings, until at last it is under way and sails off.
In the air the vulture wins our admiration. Its great wings, long and broad, hold the bird aloft like a kite. Adjusting its wings to the wind, it progresses for miles with never a wing beat, or rises very high in the air, nearly out of sight from the ground. In soaring, the vulture raises its wings to a short angle above the line of the back, making a shallow V in the sky, and often the wind pushes upward the separated tips of the primary feathers. As it moves along it sways a little from side to side, not rolling like a ship at sea, but teetering, balancing like a tight-rope walker, but slower. When the bird sweeps past us just above the treetops, we see the flight as a steady rush through the air; we see the head turn as the bird studies the ground.
Usually we see the turkey buzzards flying alone at no great height, but sometimes they collect in the sky, dozens together, and wheel about. The habit of gathering into flocks is much less marked than that of the black vulture, and they do not go in packs during the day as the latter birds do.
M. P. Skinner, writing to Mr. Bent of the buzzards' habits, says of their roosting: "At night they gather in a roost, usually located on high trees in a low or swampy area in the depths of the forests. At other times I have seen single buzzards in pines comparatively near the ground as well as on the very tops."
Ludlow Griscom tells me that the vulture is a late riser, seldom being seen on the wing until an hour after sunrise. The ground mists, which often obscure the southern lowlands early in the morning, probably delay the vulture's search for food until long after the time when most birds are stirring.
Mr. Tyrrell, in his notes, thus describes a flock of turkey vultures going to roost:
Today (February 22, 1932) at about 4:30, we were seated beneath a large white oak, whose upper limbs were white with excreta, while on the sombre floor of the forest beneath there was a whitish ring of the same material. As we sat there, the great birds would sail noiselessly over, sometimes their small, naked, red heads gleamed in the last rays of the sun, their dark, silver-lined wings moving only to catch movements of the air currents, as they glided by. Some, after alighting, would shake themselves until every feather was ruffled, giving them a most unkempt appearance. Others would alight on a branch where one or more were already roosting, and the impact of the landing bird would throw them off their balance and result in many awkward and ludicrous balancing movements. Often they would sit and preen, and some were always watching the movements of the neighborhood, cocking their heads first on one side and then on the other to see each newcomer. A few seemed to be resting, oblivious of what was going on. there were 71 in the trees at 5 p.m., 113 at 5:25, and 147 at 5:55.
While brooding small young, the turkey vulture sticks to the nest tenaciously, appearing very tame or stupid, allowing itself to be handled or even feigning death. Mr. Tyrrell got close enough to one "to grab her, and lifted her off the young, she not showing any resistance. As I lifted her, she disgorged a mass of half-digested, decayed flesh that was plenty odorous. I held her over the nest by her wings, and every time we let her go, she would put her head under the log with only her back showing. We thought she must be sick or wounded, for she acted so queerly, always with her head hanging and not showing the least inclination to get away. It was suggested that we put her on top of the log and possibly get a picture or her, so we did; but no sooner had she touched the log than off she flew, soon to be joined by her mate."
Speaking of their relation to other birds, Skinner notes that "small birds had no fear of the buzzards and vultures flying over, although they quickly took alarm if a hawk appeared. Buzzards often swept over within a hundred feet of doves, meadowlarks. . .and many others without alarming them in the least."
Since the days of Audubon naturalists have speculated on whether the vulture finds its food by sight or by scent. They have sought to find the answer by experiments on the bird and have published the results of many of these. After going carefully over the literature on this fascinating subject--too large a field to do more than summarize here--a reader cannot feel convinced that the problem has been definitely solved, even now. The evidence shows him that the vulture has keen eyesight and that it has an acute sense of smell. The reader finds running through the controversy, however, a great deal of contradiction and refutation; no one article stands out as indisputable proof on either side to the exclusion of the other side, and many experiments present to the vulture problems that it would never meet under natural conditions.
Experiments in which food is concealed in boxes, covered by canvas, or wrapped up in paper parcels make trial only of the bird's ingenuity; they do not call for the employment of the faculties with which nature has equipped the bird to use in finding its food. On the other hand, the experiment of exposing to the vulture's view the stuffed skin of an animal arranged to simulate a carcass does call into play the food associations of the bird. However, when the bird is not lured to the bait, it may be either because its nostrils do not inform it of the presence of food or because its eyes do inform it of the deception. Another difficulty in interpreting the vulture's behavior arises from its habit of reconnoitering before it begins a meal.
The vulture does not have to move quickly to catch its prey; it has only to find out where it is, and to make sure that the body is ready to be eaten--that it will not move. There is never need to hurry, so the bird reconnoiters, examining from a distance with a deliberation that allows time for the use of all its senses. Therefore, experiments conducted on birds in the field, presumably in possession of all their senses, do not suffice to show whether the bird is seeking its food by one sense or another, or by a combination of senses, but merely test the bird's general intelligence.
P. J. Darlington, Jr. (1930) has made, from the viewpoint of an entomologist, some very interesting and novel observations on this subject, noting "a possible factor in the bird's behavior which seems to have been overlooked." Here is his story:
The first incident took place at the Harvard Tropical Laboratory on the Soledad sugar estate near Cienfuegos, Cuba. In November, 1926, some dead fish were put out near Harvard House to attract beetles, but were stolen by Turkey Buzzards the first day. The bait had been hidden under fairly large stones, and since it was placed beside a garden where people were frequently moving about, there is no reason to suppose that the birds were attracted by my actions. They may, indeed, have smelled the fish, but it seems just as likely that they saw the insects which collected and which would have given the set away to any intelligent human being. Near Santa Marta, Columbia, in 1928, the same sort of thing happened, for when dead iguanas were put out they were invariably discovered by Vultures, even when the baiting was done in scrubby woods. The most rational explanation in this case seemed to be that the birds had heard the carrion-drawn flies.
The literature to date leaves the reader with the belief that the vulture is a bird not very intelligent from the human standpoint, but alert and keen to detect the presence of food by every sense at its command. ***
Voice.--For the most part, the vulture is a silent bird. Dr. Pearson (1919) says: "Over the coveted carcass they flop and hiss and even fight in a bloodless sort of way. Aside from this hissing and an occasional low grunt, the birds appear to be voiceless." The grunt he speaks of is a raucous growl or snarl, suggesting a note of some of the larger herons.
Field marks.--The turkey buzzard and the black vulture, large, dark-colored birds with a soaring flight, resemble each other somewhat in the air. The buzzard, however, is dingy brown; its tail is rounded at the tip and, carried nearly closed, projects beyond the wings in flight, whereas the vulture is black with a square-tipped tail, which fits snugly between the wings. The posterior half of the buzzard's wing, seen from below, is gray, the color extending to the end of the wing. The vulture's wing is black with a gray tip, and the bird flaps its wings much more frequently than the buzzard does. At close range the buzzard's head and neck are seen to be dull red. These parts in the vulture are black.
Coues (1874) brings out the difference in the shape of the wings when he says of the buzzard that "the fore-border of the wing is bent at a salient angle, and there is a corresponding reentrance in its hind outline," and of the vulture that "the front edge of the wing is almost straight, and the back border sweeps around in a regular curve to meet it at an obtuse point, where the ends of the quills are neither spread apart nor bent upward."
The bald eagle, a much larger, sturdier bird than the buzzard, is at once distinguished by its more conspicuous head, proportionally longer secondaries, and powerful, driving wing beats.
The California condor, compared to the buzzard, is a giant.
Enemies.--W. E. D. Scott (1892) reports that in Jamaica the vulture is "said to have decreased greatly in numbers in the past few years, being preyed upon, like all other ground, and many low tree builders, by the mongoose."
The nestlings are subject to attack from predatory animals, but the adults have few enemies.
It was feared at one time that the vulture should be held responsible for the spreading of hog cholera, but the bird has been cleared recently of the suspicion. Howell (1932), quoting from the 26th Annual Report of the State Board of Health of Florida, 1914, says that "the virus of hog cholera is digested in the intestinal tract of buzzards and the droppings of buzzards fed on the flesh of hogs dead from cholera do not produce cholera when mixed in the feed of hogs."
Frank L. Burns (1906) recounts that when a number of birds, among which was a vulture, were presented to an Italian workman, "the vulture, being the largest, was naturally considered the prize, so it was cleaned, and stuffed with plenty of garlic, and the entire household proceeded to make a meal of it; with the result that all were made deathly sick."
Winter.--Winter, with its frost and
snow, drives the bird from the northern part of its summer range,
for, as Thomas H. Jackson (1903) says, "to obtain food here
[Pennsylvania] in zero weather, with deep snow covering
everything, would seem for them an impossibility."
Turkey Vulture* Cathartes aura
*Original Source: Bent, Arthur Cleveland. 1937. Smithsonian Institution United States National Museum Bulletin 167 (Part 1): 12-28. United States Government Printing Office