Contributed by Charles Wendell Townsend
[Published in 1937: Smithsonian Institution United States National Museum Bulletin 167 (Part 1): -]
If one could forget the unsavory feeding habits of the black vulture
and remember only the pleasing attributes of its flight, one would
place this bird among the most distinguished and interesting of
avian friends. As a feature of the landscape in its flight and
soarings on high--and after all this is the feature most evident--the black vulture appeals to our aesthetic feelings, while the
mental effort needed in distinguishing it from the turkey vulture
and from larger hawks and eagles adds greatly to its interest. It is
a bird well worth seeing and watching.
Spring.-- As the black vulture is a resident throughout its breeding
range except in the extreme northern parts, a marked spring
migration does not occur. It seems to be fond of the neighborhood of
the sea and generally outnumbers the turkey vulture in these
regions, while it is outnumbered by the latter farther inland. As a
straggler or wanderer it has been recorded as far north as Quebec
and New Brunswick, while its breeding range extends north only as
far as Maryland and Virginia.
Courtship.-- Aretas A. Saunders (1906) thus describes the courtship of
this vulture, which "took place on the ground in the shade of a
small lime tree": "In a circle in front of the female were
three admirers, who, with their wings partly spread, were rapidly
ducking their heads to her like well-trained servants. She paid
little attention, and soon turned her back on them. They persisted
in their attentions till she finally got disgusted and flew away,
with her suitors in close pursuit."
Audubon (1840) gives a more graphic account as follows:
At the commencement of the love season, which is about the beginning
of February, the gesticulations and parade of the males are
extremely ludicrous. They first strut somewhat in the manner of the
Turkey Cock, then open their wings, and, as they 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. When these actions have been repeated five or six
times, and the conjugal compact sealed, the happy pair fly off
and remain together until their young come abroad.
Simmons (1925) describes the courtship of the black vulture as
observed in Texas:
During February and to the middle of March, the love-flight or
courtship flight of the two birds may often be seen at the breeding
grounds, lasting from two to ten minutes, in rapid, prolonged,
wide-spreading circles. In the air over a thickly-populated nesting
area, such as a honey-combed cliff or canyon wall in the hills, as
many as 25 or 50 pairs may be seen going through these nuptial
ceremonies during early March, presenting a slowly-moving, gyrating
maelstrom, circling and sailing in close spirals, one of a pair
continually following the other; out of this maelstrom a female
occasionally drops, the male a few feet behind, and then a chase
ensues, dropping, darting, wheeling with incredible speed, wing tips
of one touching the wing tips of the other In the twists and turns
of the play. A male performing before a female perched high on a
dead tree overlooking the chasm often circles high in front of her,
half folds his wings and dives straight for the earth, his wings
shrilling and whistling until he zooms upward again to resume his
circling.
C. J. Pennock writes: "What I take for a mating-time flight I
have noted frequently in February and early March [in Wakulla
County, Fla.], namely two birds in rapid flight in close company
through the tree tops and open country, sometimes lasting three to
five minutes."
Wayne (1910) says of South Carolina: "The birds mate in
February, and when engaged in this pleasure utter a hissing sound
which can be heard at a distance of several hundred yards."
S. A. Grimes sends us the following account:
I was returning home from a short trip to Baldwin Bay and noticed
two vultures In a tall dead cypress in a swamp about 300 yards off
the highway.
This aroused my curiosity, and I turned into a road that put me
within 100 yards of the birds. Without getting out of the car, I
focused my glasses on the birds and presently saw one hop over to
the branch on which the other was perched. This bird, which was
undoubtedly the male, alighted with his wings outstretched above his
back and, holding them in this position, sidled up so close to the
other that she was forced to back away on the limb. Losing her
balance, she flopped to another branch and was followed by the male,
who continued to hold his wings above his back in such a manner that
the tips almost touched. The two birds "necked" a little,
and the female pecked feebly at her mate's head and breast when he
pressed her too hard out on the branch.
This performance was repeated four times, and each time I looked for
copulation to take place, but the female was not agreeable. The male
finally folded his wings and perched quietly beside his mate. They
remained thus for about 15 minutes, each occasionally pecking gently
at the other; and once I noticed that they grasped each other's
bill, as doves are wont to do. I could plainly see, too, that the
birds parted their mandibles repeatedly, as If making some sound,
but none was audible at my distance. The birds suddenly sprang into
the air and flapped away, after I had watched them 25 minutes. This
was on January 31.
Nesting.-- The heading of this section is in a literal sense
incorrect, for no nest is made by the black vulture, and the eggs
are laid without this preparation. As bits of stick and weed stalks
as well as dead leaves strew the ground in many places, the eggs may
be deposited on these, but only incidentally, for these are not
collected to form even the semblance of a nest, and there is no
hollowing out of the ground as a receptacle for the eggs. Wayne
(1910) called attention to an aesthetic habit of the bird that may
have been peculiar to his region in South Carolina and that does not
appear to have been noticed by other observers. He says: "It is
a peculiar habit of this bird, which I have found to be almost
constant, to have pearl, bone, and china buttons, as well as pieces
of glass and figured china, around and under the eggs."
As there is no nest to hold the eggs, these cannot be placed on
branches of trees but must necessarily rest on the firm foundation
of the ground or at the bottom of hollow stumps, sometimes as much
as 8 feet above the level of the ground.
Hollow stumps, access to which is only from the top, are commonly
chosen for nesting by the black vulture. In some instances there may
be an opening at the ground by which the bird may enter and leave.
When the stump is 6 or 8 feet high and the nest is at ground level,
the entrance and exit of the bird from this chimney-like structure
must require the use of both the wings and feet, when the bird
scrambles up and out. I was told by an ornithologist that once when
a boy he climbed down for the eggs into one of these nesting sites,
and was unable to get out until a companion came to his rescue.
Edward J. Court (1924) reports a nesting "in a large white oak
stump in a cavity about two feet below the level of the
ground."
C. J. Pennock describes the nesting two years in succession of a
black vulture "in a large decayed hollow tree, the entrance
five feet above ground the eggs being placed on a level with the
outside round. In every instance when the nest was visited, the
brooding bird became alarmed at our approach, and we could hear her
flapping to scramble up and escape at the elevated entrance."
J. B. Carroll, of Houston, Tex., says in a letter that he has seen
many nestings in standing trees hollow at the base; "sometimes
the eggs were at a level not far below the entrance, but I have
known the eggs to be placed on the ground in the hollow, with the
entrance six or eight feet up. Usually these entrance holes are not
higher than that from the ground, but I have seen them as high as
fifteen feet." A hollow in a standing tree sufficiently large
even if at a considerable height above the ground might be used by
this bird, and I was able to find one such record. Charles E.
Stockard (1904) found the eggs of the black vulture "about
sixty feet up in a huge poplar tree which stood in a cotton field
that had been cleared for five years. In the crotch of this tree
there was a large hollow running down about three feet and slightly
sheltered above by the inclination of one of the limbs that formed
the crotch. The eggs were deposited on the floor of this hollow.
This was the only nest of this species that was observed more than a
few feet from the ground. It is probable that the birds occupied
this tree while it stood in the woods and when the land was cleared
in 1897 the tree, being a large one, was deadened and left standing
and the birds continued to use it as a nesting site." This is,
of course, a very exceptional case. A still more unusual site is
recorded by O. H. Baynard (1910), who in Florida found a black
vulture incubating its eggs in a Ward's heron's nest in a cypress
tree some 90 feet above the ground. As he collected the eggs, there
is no doubt about the identity.
Where hollow stumps and standing trees occur, they seem to be
favorite nesting sites for this bird, but elsewhere the eggs are
laid on the ground, often in dense thickets of palmetto, yucca, tall
saw grass, or small trees, although sometimes exposed to the full
light of day in the open. The shade of a partly fallen tree trunk is
another favorite site, as well as the shade of a rock or under
boulders, and, especially in limestone country where caves abound,
the eggs are often laid in a shallow cave on a cliff side.
In its nesting habits the black vulture is often gregarious, as
shown in the following description by Walter Hoxie (1886) of the
nesting on Buzzard Island, 3 miles from Beaufort, S. C., where a
dozen or more pairs nested yearly:
There is never the slightest attempt at forming a nest, or even
excavating a hollow. The eggs are laid far in under the intertwining
stems of the yucca, and in the semi-shadows are quite hard to be
seen. The parent birds, however, have a habit of always following
the same path in leaving and approaching their precious charge, and
after a little experience I learned to distinguish these traces so
well that I seldom failed to follow them up and secure the coveted
specimens. This track is seldom, If ever, straight It winds under
and around the armed stems, and, the difference In bulk between a
man and a Buzzard being considerable, the pointed leaves find a good
many of a fellow's weak points before he reaches his prize.
Quite rarely I have found eggs on the other parts of the island, and
once or twice in completely exposed situations, with not even an
attempt to get under the protection of an overhanging bush. Possibly
these belonged to young birds which had still much to learn in
regard to ways of housekeeping.
Charles R. Stockard (1904) says: "The black vulture was found
depositing her eggs in more widely different situations than any
other bird observed. The favorite site was a large hollow log, or a
tree having a huge hollow base with an opening only a few feet up,
so that the female might be able to jump out of the nest." He
notes the following nestings of this bird: "One pair for three
seasons nested in a large hollow sycamore log that lay across a
small stream and served as a 'foot log' for a little-used path in a
swampy wood. At least three people a day must have walked over the
log as the vulture sat calmly on her eggs." In another case
"a set of two eggs was found lying on the bare ground under a
large tree that had been uprooted and had fallen so that its trunk
made an angle of about fifteen degrees to the earth. The eggs were
placed below this trunk, which was four and a half feet above them,
and thus slanting sun rays could have fallen upon the spot but for
the heavy foliage of the wood." Two sets of eggs were found on
the ground in a dense cane thicket. Another set was found in a cave
in a steep clay bank bordering a creek. The entrance of the cave was
7 feet wide, it was 2 1/2 feet high, and ran back 6 feet. The eggs
lay in the back of the cave.
James A. Lyon, Jr. (1893), writing of the limestone bluffs on the
Cumberland River in Tennessee says: "The most of these bluffs
have 'caves' or holes running back into them only two or three feet
deep, others deeper. It is in these 'caves' that the black vulture
usually deposits its eggs, though sometimes they are found under an
overhanging ledge of rock. As a general rule they do not go far into
the bluff, but lay near the entrance to the hole."
Eggs.-- [AUTHOR'S NOTE: The black vulture lays normally two eggs,
occasionally only one and very rarely three. They vary in shape from
ovate to elliptical-ovate or elongate-ovate, very rarely fusiform.
The shell is smooth but not glossy. They can usually be
distinguished from turkey-vulture eggs by being somewhat larger,
having a peculiar ground color, and being much less heavily marked.
The usual ground color is pale gray-green, sometimes pale bluish
white or dull white and rarely creamy white. There are usually a few
large blotches or spots, mostly near the large end or in a ring
around it; some eggs are more evenly spotted and some are nearly
immaculate. The markings are mostly in dark browns,
"chestnut", "liver brown", or
"chocolate", but sometimes in lighter browns,
"russet" or "tawny", with occasionally a few
"Quaker drab" spots. One very pretty egg is heavily
blotched with "pale purple drab", with a few spots of
"bay"; another is heavily blotched and finely spotted with
"burnt sienna"; but such eggs are exceptional.
The
measurements of 51 eggs average 75.6 by 50.9 millimeters; the eggs
showing the four extremes measure 90.5 by 55.9, 75 by 56, 66.5 by
51, and 67.3 by 47 millimeters.]
Young.-- The incubation period is variously stated to be anywhere from
28 to 39 days; and both parents assist in the incubation. Baynard
(1909) watching 21 nests found the incubation was usually 28 to 29
days, in one case 30 days. Edward S. Thomas (1928) reports it as
about 39 days in one case. The young, helpless at first, may stray a
little from the nest on the ground at a comparatively early age,
but, according to Baynard (1913), they are about 14 weeks old before
they are able to fly. Simmons (1925) quotes H. J. Kofahl's statement
that the young remain at the nesting site for about 60 days. Howard
Lacey (1911) says "the young feign death when disturbed."
The Rev. James J. Murray, of Lexington, Va., gives the following
interesting account of an experience with young birds on the summit
of House Mountain in Virginia, an elevation of about 3,000 feet:
The nest cavity was under a pile of huge boulders. The cave had an
opening above large enough for a man to crawl into, and tunnels from
two sides at the ground level. One of the parent birds flew out of
the upper opening as we approached. There were two young birds, one
somewhat larger than the other. They appeared to he three or four
weeks old and to weigh about three pounds. They had no feathers and
were covered with a thick down of cream buff color, almost reddish
above. As we went into the hole they began to vomit large pieces of
meat, almost choking in the effort, and continued to do so at
intervals as long as we were there. They constantly made a loud
blowing noise through slightly opened mouths. It was not a hiss but
more like the noise of a bellows. At every effort to get them out
into the open they scrambled back into the darkness, jamming
themselves under the overhanging rocks and burying their heads in
the cracks. When we finally pulled them out to the end of the tunnel
in a vain effort to get a good picture in the dim light, they fought
each other fiercely and pecked at our hands.
Edward S. Thomas (1928) describes the feeding of the young as
follows:
The adult bird lowers its bill to the young, which immediately
inserts its beak between the opened mandibles of the adult. The
adult, with or without a perceptible gulping movement, regurgitates
the food, which is eaten by the young with a nibbling movement of
its mandibles. We were certain that at times the adult extruded
broth-like drops of liquid, which the young secured from the
scarcely opened mandibles of the old bird. At other times the young
birds obtained the food from the middle part of the adult's beak,
hut the preferred source of supply, without question, was far up in
the corner of the old one's mouth, where the young birds thrust
their bills whenever they were able to do so.
The adults fed either from a standing position, or while brooding
the young. The day was cold and the old birds brooded almost
continually. The young were fed repeatedly. Between the hours of 6:03 a. m. and 5:48 p.m., there were 17 distinct feeding periods,
some of which continued over an interval of seven minutes or more.
The young were very matter-of-fact about taking their food, and at
no time showed the eagerness, which characterizes the young of most
birds. This perhaps may be accounted for by the fact that the young
were kept gorged with food continually, the distended stomachs being
plainly visible from the blind. On this occasion, the young
apparently were fed liquid food only, the liquid being described by
Geist as having a milky appearance. On several occasions, solid
food, having the appearance of flesh or connective tissue, was
regurgitated, which the young attempted to seize, but on each
occasion the parent re-swallowed the material.
Plumages.-- [AUTHOR'S NOTE: The young black vulture is warmly
covered except on the head, with long, thick, heavy down of a rich
buffy color. Mr. Thomas (1928) says:
At 17 days the pinfeathers of the wing begin to show. At 39 days,
the young were almost full-grown, but the wing quills were only five
inches in length, and the tail feathers of the larger of the two
birds, two inches. At this age, there were no other feathers. On
June 12, when the young were about 52 days old, the scapulars,
tertials and practically all of the wing coverts were feathered, and
quills were appearing on the breast. A week later, the upper parts
were practically covered, although there was still a great deal of
down showing, hut while feathers were appearing on the breast dad
under parts, they were concealed by the down. On June 26, at 66
days, one of the young was able to fly up to the top of the box
blind. By July 4, they had left the cave, having a period of from 67
to 74 days in the nest.
Immature birds during their first year are much like adults, but the
plumage is duller black and less glossy, and the naked skin of the
neck and head is partially concealed by a scanty growth of short,
black, hairy down. I have been unable to trace subsequent
molts.]
Food.-- The principal food of the black vulture gives it its common
name of carrion crow, for carrion is the chief article of its diet.
This food is to be found in the sewers and dump heaps and about
butchers' shops in southern cities, as well as in the fields and
forests where animals have come to untimely ends. The methods used
in searching for and disposing of this food will be described
farther on under "Behavior." As scavengers, especially in
cities where these functions are not attended to by man, the black
vulture is considered a valuable servant. Black vultures will also
eat fresh meat, and butchers must watch their stalls carefully when
these birds are about.
J. D. Figgins (1923) found that black vultures in the neighborhood
of Bird Island, La., were very destructive in some of the heron
rookeries and stated that "it is a frequent occurrence to
observe a vulture with a struggling young heron dangling from its
beak. In regions where cattle raising has replaced the cultivation
of rice, the Black Vulture is credited with considerable damage to
the herds by tearing the eyes from calves at the time of birth and
instances are cited of a like treatment accorded cows while in a
weakened condition. I personally saw one of these tear the tail from
a small pig, and was informed that the practice was of too common
occurrence to excite comment." O. E. Baynard (1909) reported
that these birds were very destructive to young pigs and lambs in
Florida, and he has known them to take young chickens. Young herons
are frequently devoured. Audubon (1840) says of his experience with
the bird in Florida: "I observed them many times devouring
young cormorants and herons in the nest."
The United States Biological Survey recommends local control where
"through their predatory habits and concentrated numbers, both
turkey buzzards and black vultures have become a menace to new-born
pigs, calves, lambs, and kids" (Redington, 1932).
Although it is common knowledge that black vultures eagerly devour
fresh meat at butchers' stalls, C. J. Maynard (1896) says of this
vulture that they "are more emphatically carrion feeders than
the latter described species [turkey vulture] and will seldom eat
fresh meat but prefer to wait until decomposition has set in before
beginning their feast. Thus I have frequently seen the Turkey
Buzzards gather around the freshly skinned carcass of an alligator,
and eagerly devour the flesh, while the Black-heads would wait until
it had lain for a day or two in the broiling sun before they would
attack it; then, when the odor from the decaying mass became
insufferable to human nostrils, they would eat to repletion. They
not only eat decomposed meat but feed upon animal excrement and
various kinds of offal."
Behavior.-- When a carcass of an animal is discovered, black vultures
gather at the feast, which in many cases they must share and fight
for, not only among themselves, but with turkey vultures and
sometimes with eagles and dogs. Alexander Wilson's (1832) classic
description of one of these feasts on a dead horse near Charleston,
S. C., is well worth quoting:
The ground, for a hundred yards around it, was black with carrion
crows; many sat on the tops of sheds, fences, and houses within
sight; sixty or eighty on the opposite side of a small run. I
counted at one time two hundred and thirty-seven, but I believe
there were more, besides several in the air over my head, and at a
distance. I ventured cautiously within thirty yards of the carcass,
where three or four dogs and twenty or thirty vultures, were busy
tearing and devouring. Seeing them take no notice, I ventured
nearer, till I was within ten yards, and sat down on the bank. Still
they paid little attention to me. The dogs being sometimes
accidentally flapped with the wings of the vultures would growl and
snap at them, which would occasion them to spring up for a moment,
but they immediately gathered in again. I remarked the vultures
frequently attack each other, fighting with their claws or heels,
striking like a cock, with open wings, and fixing their claws in
each other's head. The females, and, I believe, the males likewise,
made a hissing sound, with open mouth, exactly resembling that
produced by thrusting a red hot poker into water; and frequently a
snuffling, like a dog clearing his nostrils, as I suppose they were
theirs. On observing that they did not heed me, I stole so close
that my feet were within one yard of the horse's legs, and again sat
down. They all slid aloof a few feet; but, seeing me quiet, they
soon returned as before. As they were often disturbed by the dogs, I
ordered the latter home: my voice gave no alarm to the vultures. As
soon as the dogs departed, the vultures crowded in such numbers,
that I counted at one time thirty-seven on and around the carcass,
with several within; so that scarcely an inch of it was visible.
Sometimes one would come out with a large piece of the entrails,
which in a moment was surrounded by several others, who tore it in
fragments, and it soon disappeared. They kept up the hissing
occasionally. Some of them having their whole legs and head covered
with blood, presented a most savage aspect. Still as the dogs
advanced, I would order them away, which seemed to gratify the
vultures; and one would pursue another to within a foot or two of
the spot where I was sitting. Sometimes I observed them stretching
their necks along the ground, as if to press the food downwards.
The black vultures are often obliged to share their feasts with
turkey vultures, and, according to Golsan and Holt (1914), they
always get the better of the latter in a quarrel. On the other hand,
according to Audubon (1840), "should eagles make their
appearance at such a juncture, the Carrion Crows retire, and
patiently wait until their betters are satisfied, but. They pay
little regard to the dogs." In tearing off choice morsels from
the carcass with their bills the vultures brace their feet firmly on
the ground and flap violently with their wings to aid them in
pulling away.
Their movements on the ground are not graceful. Aretas A. Saunders
(1906) graphically describes them as follows: "When the vulture
is taking his time about getting around, he moves with a very
solemn, sedate walk, carefully placing one foot in front of the
other. When he is in a hurry, however, he slightly spreads his wings
and indulges in what looks like hopping but is really a very
one-sided run. At first sight he seems to put both feet on the
ground at once, but in reality he puts down the left foot first and
takes his long step with the right foot."
In the air, on the other hand, the black vulture is much more at his
ease, but he is far inferior in flight to the turkey vulture, owing
to his shorter wings and tail and to his greater weight. While the
turkey vulture sails in majestic circles on motionless wings, borne
up by the air currents, the black vulture on the same up-currents is
obliged to flap his wings from time to time. If the up-currents are
strong, his need for flapping is reduced, but he never equals the
grace of the turkey vulture. I once compared the flight of the two
birds on a calm warm day in Georgia, as they were soaring over a
sparse pine forest. They were both about 60 yards above my head as I
reclined on the ground and about 40 yards over the forest. The
turkey vulture soared in small circles, neither rising nor falling
and without once flapping its wings, which with the tail were merely
adjusted from time to time to the air currents. The black vulture,
on the other hand, flapped its wings quickly at frequent intervals.
The contrast was very marked. After a while they both sailed off.
Whether they were inspecting me as possible carrion I do not know.
On another occasion, when lying outstretched on a sandy Florida
beach, I was startled by the shadow of a vulture passing over me and
at once sat up. I have been told that this is a habit of vultures to
determine whether a body is alive or dead. That they fly near for
this purpose is not improbable but one cannot believe that they are
able to plan to have their shadow fall on the body.
When a black vulture flying and circling at a great height becomes
aware of a carcass lying far below it, the bird at first circles
down but soon drops with great swiftness, with legs hanging and, at
times, wings flapping furiously. Such actions of descent from a
height immediately attract the attention of other vultures on the
ground or roosting in trees and they at once follow up the clue. One
such action, even a mistaken one, can quickly collect a flock of
vultures.
The question that has been much discussed then arises, as to how
these birds find the carrion. It is evident that sight is of great
importance, and the way in which vultures turn their heads in flight
suggests that they are all the time on the lookout for their food.
As carrion is so evident to our own sense of smell, even from a
great distance, it is natural for us to suppose that these birds
also are guided by the sense of smell, especially when trees or
bushes partly conceal the carrion. In fact, this belief in the use
of the smelling powers has always been a popular one, but since the
experiments of Audubon and Bachman (1835) it has generally been
accepted that sight alone guides the birds to their food. These
experiments, made chiefly on the black vulture, are summarized
briefly as follows:
(1) A carcass securely hid in a brier and canebrake was not detected
by the birds, although the odor was very marked and attracted dogs.
(2) Carrion on ground covered by a frame of brushwood 12 inches
above it was not detected by vultures who passed over it during the
25 days of the experiment.
(3) Fresh meat, placed on canvas covering carrion, was devoured by
vultures standing on the canvas, but they did not detect the
carrion.
(4) A blinded black vulture did not notice carrion placed within an
inch of its nostrils.
A few observers since Audubon occasionally have tested the sense of
smell in black vultures, but their findings are generally not
conclusive, are not free from the possibility of error, and are
often contradictory. Thus, C. J. Pennock writes to me that in
Florida he placed "the offal from a large green turtle on the
ground 15 or 20 yards within a grove of closely growing pine trees,
averaging perhaps 50 feet in height and with tops thickly
interlocked but with no side limbs for 30 feet up. At 8:15 a. m.
the meal was ready; at 9 o'clock a single black vulture was atop the
fence nearby; at 9:40 there were 40 birds, all black vultures
sitting on the ground, perched in trees or regaling themselves. No
vultures were in sight when the table was spread, and it was thought
the repast could not be seen by a flying bird at the nearest open
side of the grove, but of this there is a possible doubt."
Dr. Frank M. Chapman (1929) at Barro Colorado Island has made the
latest and most careful experiments. Most of them were on the turkey
buzzard, and he says that "some of my results leave no room for
doubt that the turkey buzzard has a highly developed sense of smell.
From others, exactly the opposite conclusion may be drawn." On
one occasion two black vultures perched on a tree about 125 feet to
leeward of a small house where carrion was concealed. These were the
first black vultures he had seen alight on the island.
There is one source of error that so far as I know has not been
considered in these experiments and may account for some of the
contradictory results. This was brought out by Darlington (1930),
who in collecting beetles by the use of carrion bait in tropical
regions also attracted vultures, and was led to the following
conclusions:
Soon after the death of an animal, except in unusual cases or during
cold weather, the body attracts numbers of flies and beetles, some
of which may continue to circle about It for several hours or days.
The resulting congregation of insects is noisy and conspicuous, and
of a sort which does not occur except about decaying material, so
that it may be considered more or less characteristic of the latter.
Since Vultures can undoubtedly see and perhaps hear such insect
swarms at a distance, they have probably learned to recognize their
significance, just as we recognize the significance of gatherings
of the Cathartidae.
Aretas A. Saunders (1906) found that the lives of black vultures on
a rubber plantation in Nicaragua followed a regular routine,
influenced only by hatching and the character of the weather. Early
in the morning they sat on fence posts or walked about the
plantation in search of bits of food. At noon in fine weather they
circled high in the air, coming down toward evening for another
walk. At sunset they flew one after another to fence posts, thence
to the top of a large tree, where they waited until all were
congregated. All at once they flew to another tree and thence to
another, until they found one to suit their fancy. They seldom slept
in the same tree two nights in succession, though they always
commenced operations from the same tree. Saunders continues:
Butchering day, which occurs at irregular intervals, is the
important day in the life of the Vulture. As soon as the men go down
to the potrero to drive up the cattle, they know what is coming.
They gather together on the fence posts and shed roofs, watching the
movements of the men with an air of expectancy. Sometimes they wait
for three or four hours before the butchering is finished and the
remains thrown out to them. Then there is an instantaneous scramble.
Each Vulture takes hold with his beak and begins to pull and hiss
and flap until the piece he holds breaks off, when it is swallowed
as quickly as possible and a fresh hold taken. At this rate the
whole feast is consumed in an hour or two, when the vultures go back
to time fence posts and sit in silence for the remainder of the day.
Black vultures are very social in their habits and often resort to
regular roosts. One such I visited at Buzzard Isle, Lake Lamonia, in
northern Florida. The roost was in big live oaks, mostly dead, and
at about 11 o'clock in the morning contained some 200 black vultures
and half a dozen turkey vultures. The birds did not leave when I
walked beneath them on a ground devoid of vegetation and covered
with their droppings and many bones. The odor was strong of a
chicken yard, but not of carrion. Toward sunset I saw from a
distance a number of flocks of about 20 vultures each, sailing and
flapping high up toward the roost. On another occasion on the
Vermilion River, La., I passed at sunset about a hundred of these
black creatures sitting on the limbs of moss-draped cypresses, many
more in a nearby field and six or eight on the roof of a deserted
house. A short distance away several were perched on the floating
body of a dead cow. It was a mournful sight.
Audubon (1840) describes a visit by John Bachman and himself to a
roost of black vultures that attended to the offal of Charleston, S.
C. This roost was in a swampy wood of about two acres, across the
Ashley River, two miles from the city. "When nearly under the
trees on which the birds were roosted, we found the ground destitute
of vegetation, and covered with ordure and feathers, mixed with the
broken branches of the trees. The stench was horrible. The trees
were completely covered with birds, from the trunk to the very tips
of the branches." They estimated the number of vultures at
several thousands.
Simmons (1925) states: "Just before daybreak, when a reddish
glow begins to show in the eastern sky, black vultures begin to
leave their roosts in the mountainous country, passing over in a
continuous long string by ones and twos, or as many as half a dozen
at a time, moving eastward towards the slaughter pens or to spread
out over the open country and begin their tireless vigil for
carcasses." They return just after sunset.
B. J. Blincoc (1922) observed an unusual flight of these birds in
March in Nelson County, Ky., where the black vulture is generally
scarce at this season. The flock of 92 individuals "presented a
beautiful appearance as the birds soared in a spiral column, each
bird taking, intermittently, a few short wing strokes. At times the
whole flock in a long train coursed across country on set wings in
an orderly manner suggesting the movement of a flock of water fowl,
but not a bird moved a wing until they again maneuvered into a
spiral column." There was not a single turkey vulture among
them.
J. J. Murray (1928), at Lexington, Va., found about 60 vultures at a
slaughter pen, and at least 40 of them, he says, were black
vultures. "As we disturbed them, they began walking in single
file in a long procession up a steep hillside for 200 or 300 yards,
and then near the top took flight." In a letter he says:
"This procession was not in order to reach a high place from
which to take off, for many of them had jumped to the ground from
the top of the slaughter house as the procession started." To
rise from the ground in calm weather it is sometimes necessary for
the black vulture to hop or run along for 20 or 30 feet, beating its
wings violently until it is able to take off.
In cold weather these vultures often sit around chimney pots and on
chimneys to obtain some of the warmth. In wet weather they present a
most dejected appearance, with wings drawn in close to the body and
with back and tail in an almost vertical position. They have a habit
of spreading their wings and tail to dry and air when the sun is
shining. When alarmed or caught they eject the contents of their
stomachs with great quickness and power.
In southern regions it is unnecessary to bury a dead animal to
prevent long pollution of the air, as in the North; the farmer
merely drags the carcass to a secluded spot and the vultures soon
strip off and consume the flesh and entrails. Around butchers'
stalls and in cities where offal is thrown into the street, the
birds are semi domesticated and walk around almost underfoot. Owing
to these habits of the black vultures in consuming carrion and offal
of all sorts, the danger of their spreading disease by pathogenic
bacteria dropped directly from the vultures' feet and plumage, or by
their dejecta, has been given serious consideration. If, for
example, anthrax may be spread in this way from the carcass of a
horse dead of that disease, it may be better economy to burn or bury
the body than to leave it to the vultures.
Dr. Casey A. Wood (1922) relates an experience with black vultures
in Georgetown, British Guiana, where until 1921 large numbers of
them frequented the city, especially in the region of the
slaughterhouses, and were to be seen daily perched on the roofs of
the houses. The prejudice among the inhabitants in their favor as
scavengers was strong, but it was found that the birds polluted the
drinking water, which was largely supplied by roof drainage. It was
proved that serious pollution of the drinking water was brought
about by the birds' habit of bringing filth to the roofs and also by
the pathogenic bacteria in their feces. Analysis of the cistern
water of houses protected by wires stretched above the ridgepole to
prevent roosting showed it to be free from pathogenic bacteria,
while cisterns filled from unprotected roofs, especially those known
to be patronized by black vultures, were often shown to be infected
by horrific germs. Since 1921 the black vultures have been nearly
banished from the city by shooting and systematic frightening away.
Herbert W. Brandt communicates the following about the turkey and
black vultures in Kleberg County, Tex., where both are abundant:
"It is claimed by Mr. Kleberg that they spread the deadly
anthrax to the cattle, and also other cow diseases. He trapped 3,500
buzzards on the Laureles Ranch alone during the winter of 1918-19.
The trap is simply a wire-enclosed yard with some foul smelling
carcasses of cows, hogs, etc., as bait and an entrance that closes
behind the bird and keeps it in. A Mexican then enters the trap with
a club and kills the birds and burns the bodies."
In a publication of the Biological Survey (Redington, 1932), it is
stated that "the Biological Survey has discouraged the general
destruction of turkey buzzards and black vultures. These birds have
been accused of being important carriers of livestock diseases, but
skilled investigators have shown that the virus of charbon, or
anthrax, is destroyed in passing through the digestive tract of the
turkey buzzard. There also are on record similar data regarding the
virus of hog cholera. Experimental work of the Bureau of Animal
Industry has indicated that the transmission of hog cholera on the
feet or feathers of birds is by no means so likely to occur as is
generally supposed."
Voice.-- The black vulture is a very silent bird. Hissing, grunting,
and blowing compose its entire vocabulary, and these sounds are
rarely to be heard except when the birds are feeding or fighting.
Aretas A. Saunders (1906) describes its voice as consisting of
"a hiss and low guff, guff, guff, like a dog barking in the
distance." Pennock describes a cry as sounding like watt or
waugh. The blowing sound resembles that made by bellows. Donald J.
Nicholson (1928) says that the young hiss at an intruder and utter a
blowing note very similar to that of a rattlesnake. Edward S. Thomas
(1928) writes:
The birds were beard to give a variety of notes. Adults and young,
when cornered or annoyed, give a rasping, hissing snarl, also
described as a "snore", and "half-way between a
wheeze and a squeal" the young give this frequently in the presence
of the parents. The young also frequently make a sound which, when
they were very young, was described as "Phuh U' or "Whuh
I" Later this note became in the older birds, "Woof
I" or "Wooft I" This note apparently denotes
suspicion, and may be the counterpart of a grunting sound which the
adults frequently emit. In addition, I heard the adult give a low,
croaking "Coo," very much like a one-syllabled coo of the
domestic pigeon.
Field marks.-- When this bird is seen at close range, alighted on the
ground or on a tree, it is unmistakable. Its black head and neck
bare of feathers proclaim it to be a black vulture, although it must
be remembered that the head of the immature turkey vulture is also
dark and not red as in the adult. The other characteristics of the
black vulture are best seen in flight. Here its short, nearly square
ended tail, as contrasted with the longer rounded tail of the turkey
vulture, is evident. The feet may sometimes be seen against the tail
as they reach nearly to the end and even project a little, but it is
more difficult to see them in the turkey vulture. The wings seen
from above and below both show a light-colored space at the outer
end of the primaries, while in the turkey vulture all the primaries
and secondaries are light colored, giving the effect of a light
posterior border to the wings. While the wings of the turkey vulture
are held up at an angle in soaring, those of the black species are
as a rule more nearly horizontal, and the ends of the primaries are
more distinct and spread out like fingers. The heavier, clumsier
flight of the black vulture, with frequent flappings of the wings,
easily distinguishes the two birds, although in very favorable airs
the black vulture may soar nearly as well as the turkey vulture.
Enemies.-- The black vulture is fortunate in having few if any
enemies. Eagles and wolves may chase it away from a carcass, and
ospreys may wrathfully pursue it if it appropriates a fish from the
osprey's nest. Even man treats it with consideration in return for
its services in cleaning up carrion and offal, although in time most
southern cities may adopt the more sanitary but more expensive
methods needed in northern cities in order to escape the defilements
of these scavenger birds. In some regions, as has already been
mentioned under "Food", it may be necessary for man to
control these birds when they kill young domestic animals.
While smaller birds take alarm quickly at the sight of a hawk, they
are not disturbed by the presence of these vultures. M. P. Skinner
thus writes of a black vulture in a roost among the sand hills of
North Carolina: "They never bothered small birds--wood ducks,
blackbirds, meadowlarks and myrtle warblers among others--who seemed
to know this and to be able to recognize the vulture readily. They
showed no alarm at the vultures sailing over them, although quick to
dive out of sight when even a small hawk appeared."
Black Vulture* Coragyps atratus atratus
*Original Source: Bent, Arthur Cleveland. 1937. Smithsonian Institution United States National Museum Bulletin 167 (Part 1): -. United States Government Printing Office