Within living memory New England had no resident vultures.
In the opening years of the 20th century the turkey vulture’s range
didn’t extend beyond New Jersey, although stragglers were occasionally
spotted farther north. By the 1920s, however, turkey vultures were showing
up in New York State on a regular basis. In 1930 a turkey vulture nest
discovered in Connecticut marked the species’ first confirmed nesting
in New England. Turkey vultures nested in Massachusetts for the first
time in 1954, and now they are firmly established in the state as both
breeding birds and migrants. By the early 1970s they had pushed into New
Hampshire and by the early 1980s they could be seen in Maine.
Black vultures were slower to move into New England.
They were first recorded as visitors to Massachusetts in 1954, the same
year that turkey vultures began nesting here. Black vultures nested
in Massachusetts for the first time in 1999; the first confirmed nesting
in Connecticut came in 2002. Since both the turkey vulture and the black
vulture are newly established as New England residents, since they can
be found together, and because they lead a similar scavenging lifestyle
yet exhibit a wide variety of differences, the two species will be considered
here side by side.
Turkey Vulture (Cathartes aura)
Weight: 56-83 ounces (average of 64 ounces)
Length: 24-28 inches
Wingspan: 63-71 inches
Black Vulture (Coragyps atratus)
Weight: 56-81 ounces (average of 68 ounces)
Length: 23-28 inches
Wingspan: 55-63 inches
GENERAL APPEARANCE – Turkey Vulture
ADULT – This is a big, dark bird which when perched
suggests a particularly unfortunate specimen of poultry. Indeed, the
turkey vulture gets its common name from the fact that its red, wrinkled
head and dark body give it more than a passing resemblance to a wild
turkey. The almost featherless head and neck are a bright purplish red
and are sparsely covered with short, dark bristle feathers that are
not visible from a distance. Because the head is bare of visible feathers
it appears small. It is furrowed with wrinkles that become more pronounced
as turkey vultures age. There is a semicircular pattern of whitish to
greenish papillae or warts around the birds’ eyes that varies
from one individual to another. These papillae may be caused by bacterial
infections resulting from constant exposure to rotting meat. The male’s
head has a wattled look, but this is the only outward difference between
the genders, which are alike in size and color. The nasal septum, a
thin partition between the two nostrils, has a hole in it (this is true
of all New World vultures), so an observer can look right through a
turkey vulture’s nostrils. Which means that a turkey vulture,
should it be so inclined, can wear a nose ring. The beak is cream-colored
and long, hooked only at the tip. The eyes are grayish brown.
The body plumage is brownish black, with a pronounced
brown cast to the back. The soft feathers that encase the lower neck
form a ruff, like a thick scarf, and these feathers really are beautiful,
with a blue or purplish sheen. The legs are bare of feathers and are
visible when the turkey vulture is perched. They are pale red and may
be streaked with white excrement.
IMMATURE – Turkey vultures take two years to
develop their adult coloration. Young birds less than one year old have
a distinctly browner cast to their body plumage. Their heads are the
color of soot and covered with a fine brown fuzz, like a balding man
with a buzz cut. The wrinkles, wattles and warts that individualize
the adults aren’t present in young birds. The neck ruff lacks
the striking iridescence of the adult birds. The beak is dark, with
an ivory base. As the young bird passes its first birthday and becomes
a subadult, the head turns pink. The beak of a subadult is two-toned,
cream with a dark tip.
GENERAL APPEARANCE – Black Vulture
ADULT – Black vultures are slightly heavier on
average than turkey vultures. Like turkey vultures, they have a hunched
look when perched. The skin of the head and neck is gray and furrowed
with wrinkles. From a distance it appears bare; a close-up inspection
reveals a sparse covering of short bristle feathers. The beak, with
the see-through nostrils that characterizes New World vultures, is dark
with an ivory lower half. The beak is thinner and longer than that of
a turkey vulture. The eyes are brown. Body plumage is, as the species’
common name suggests, a deep black. A running purply sheen marks the
back and upperwing coverts. The legs are visible when the bird is perched.
They are whitish and often further whitened by streaks of excrement.
The tail is short.
IMMATURE - Young black vultures are similar to adults
but have black heads rather than gray ones. Their heads lack the wrinkles
of the adults and are clothed in soot-colored down. The beaks are dark
without a pale tip. The dark body plumage lacks the sheen of the adults’.
APPEARANCE IN FLIGHT – Turkey Vulture
The turkey vulture is incomparably graceful in flight, which is why
Andrew Wyeth’s painting “Soaring” depicts turkey vultures
riding air currents. When the bird spreads its 5 ½-foot wingspan
and is viewed from below, the wings are noticeably two-toned. The primary,
secondary and tail feathers are silvery, in contrast to the black wing
lining. The silvery or gray look to the underside of the flight feathers
is only visible from below. From above, the outer primaries have a golden
look. The upswept wings are held in a V-shape, and the outer six primary
feathers are open like curving fingers. The long, narrow tail is not
usually fanned out in flight. It appears gray, darker than the silver
of the primary and secondary feathers. The species’ red head is
not easily seen when turkey vultures are soaring. On the wing the birds
keep their heads pulled into their neck ruffs to conserve heat.
APPEARANCE IN FLIGHT – Black Vulture
Like the turkey vulture, the black vulture exhibits two-toned wings
in flight. The outer six primary feathers of this species’ wings
are greyish, with pure white shafts. From below the contrast between
the dark body and wings and the light-colored outer primaries is very
obvious. The contrast is almost as obvious from above, as when the bird
is sunning itself with outstretched wings. The thick white shafts resemble
skeletal fingers.
FLIGHT – Turkey Vulture
Turkey vultures are masterful fliers, and can be instantly recognized
by their flying style. The turkey vulture wingspan averages 5 ½
feet. The wings are narrower than those of the black vulture, the tail
is longer, and the turkey vulture averages less in weight. All these
factors add up to lower wing loading, which means that the turkey vulture
has a lot of wing area compared to its weight. Low wing loading makes
for graceful flying, and turkey vultures can ride air currents for hours
with little or no flapping. As they soar, they hold their wings in a
V-shape. This tell-tale shape of wings angled above the horizontal is
called a dihedral, and turkey vultures (unlike eagles and hawks which
tend to soar on flat wings) fly with a pronounced dihedral.
In flight the outermost six primary feathers are
splayed open like the curved fingers of a hand to give the bird more
lift. Because these primary feathers, the longest of the ten primaries,
can be moved individually, this species has superb flight control. A
turkey vulture can stay aloft at very slow speeds without stalling and
falling.
Turkey vultures have a large expanse of wing but
are relatively light in weight, so they are not steady while soaring
the way eagles are. Instead turkey vultures characteristically rock
and sway on the air currents. When the currents become strong, the wings
may be angled back, and frequently the wings are flexed below the horizontal
until the bird is bow-shaped in outline. When turkey vultures do need
to flap their wings, their wingbeats are measured and deep. The long
wings give the impression of flexibility.
FLIGHT – Black Vulture
This species’ soaring style is very different from the turkey
vulture’s. Black vultures are heavier on average, yet have a smaller
wing surface, so their wing loading is higher. This means they must
rely on stronger thermals than turkey vultures, so black vultures soar
higher. When they soar their wings do not show the marked dihedral of
the turkey vulture. Typically black vultures soar on horizontal wings
or with wings held slightly above the horizontal. When they glide downward
the wings are held flat.
The black vulture’s flapping style is likewise
very different from the turkey vulture’s. This species is more
stockily proportioned and needs to flap more often to keep itself aloft.
The wingbeats are fast (one field guide characterizes them as “almost
frantic”) and shallow, like those of a crow or blue jay. As the
wings are flapped they’re pushed forward and give the impression
of being held stiffly, awkwardly, as though the bird were out of condition.
Three to five wingbeats are followed by a “blundering glide”
(from Eagles, Hawks and Falcons of
the World by Brown and Amadon). The pale legs, held tucked
up in flight, reach almost to the tip of the short, squared tail. The
tail is so short that it doesn’t reach much beyond the back edge
of the wings.
Black vultures are still uncommon in New England,
and when they are spotted here, they’re often in the company of
turkey vultures. When the two species are seen soaring together, the
differences between them are immediately obvious. The black vulture,
with its choppy wingbeats and labored glides, cannot match the turkey
vulture’s majesty in the air.
RANGE – Turkey Vulture
The turkey vulture has a wider distribution than the black vulture and,
as we have already seen, it has been steadily expanding its range northward
in the last century. This species is found in every state except Alaska
and Hawaii. It ranges from eastern Canada down to the tip of South America.
The species is not evenly distributed over this vast range. In the United
States it occurs in the greatest numbers in the South.
RANGE – Black Vulture
This species does not enjoy the wide range of the turkey vulture. The
black vulture shows a strong preference for living near water, and it
is absent from the arid states of the West. In the East it occurs in
the Atlantic Coast states, extending now from Massachusetts down to
Florida, and west to Texas with an isolated population in Arizona. It
is most abundant in the Southeastern states, particularly Florida.
Black vultures also range down through Mexico and
Central America well into South America, although they aren’t
found south of Peru. They are very common in Central and South America.
TERRITORY – Turkey Vulture
This species requires a very large territory because the space must
fulfill three requirements: It must provide a dependable supply of carrion;
it must contain a suitable roosting site; and it must be equipped with
safe nesting sites. Turkey vultures do not defend a relatively small
territory, as many species do. Instead they range over dozens of square
miles, returning to a home roost in late afternoon. The nesting sites
may be a considerable distance away. In fact, turkey vultures don’t
appear to defend their territory at all.
TERRITORY – Black Vulture
Like turkey vultures, black vultures range over a wide space without
defending it. They have the same three general requirements of a constant
food supply and roosting and nesting sites. This adaptable species seems
able to coexist with people quite successfully, and in the tropics particularly
has become a suburban and even an urban resident. A city territory,
because of an everpresent supply of garbage and roadkill, would be smaller
than a rural one.
FOOD – Turkey Vulture
Vultures are scavengers, which means that they eat animals that are
already dead. Turkey vultures typically feed on smaller carcasses than
black vultures do. In fact, turkey vultures seem to have evolved to
exploit a particular food niche – carcasses of small animals,
which they locate wholly or in part with their sense of smell. Mammals
eaten range in size from mice to deer to livestock like cows and horses.
Reptiles, amphibians and birds are also eaten when available. When turkey
vultures feed on large animals they feed in groups, often in association
with black vultures. At such times the turkey vulture plays second fiddle,
allowing the black vulture to take control of the carcass.
One reason for the turkey vulture’s expansion
northward is the U.S.’s vast highway system, which provides the
vulture with a constant source of roadkill. Another is our creation
of landfills and garbage dumps. Live prey is occasionally taken, although
the victim is invariably small and weak or dying. The turkey vulture
is well known for haunting heron and ibis rookeries and stealing eggs
and nestling birds, living and dead. I have to wonder if one factor
in the turkey vulture’s colonization of New England might be the
comeback of the great blue heron. Now we have extensive heron rookeries
in Massachusetts, and perhaps these serve as a significant food source
for turkey vultures, at least in summer. There are a few reports of
this species fishing.
Sometimes the food consumed is not animal flesh.
Turkey vultures have been known to eat other animals’ excrement.
They have also been recorded eating rotting fruit and vegetables. In
at least one case the food eaten was pumpkins, although this may well
reflect desperation on the vulture’s part.
FOOD – Black Vulture
Black vultures and turkey vultures make different food choices. Black
vultures routinely feed on larger carcasses. This species is more gregarious
and more aggressive than the turkey vulture. Once a carcass is located,
black vultures descend on it in large numbers. In areas where the two
species occur together, the black vulture’s numbers and aggressive
behavior drive the more passive turkey vulture away from food. That
aggression also means that black vultures are more apt to eat live food.
They have been seen fishing, and they have also been observed ganging
up on live skunks and opossums and tearing the hapless victims apart.
They routinely eat nestling birds, from seabirds to herons, and they
congregate in large numbers on tropical beaches to harvest hatchling
sea turtles. Eggs are eaten as well, from bird to reptile. Newborn mammals
such as pigs and calves may be killed, or the afterbirth may be consumed.
There are reports of black vultures snipping the tails off small mammals,
and having handled this species and seen how it pulls on anything stringlike
I can well believe it.
Excrement is also eaten, as are fruits and vegetables.
Avocados and the fruit of the oil palm are recorded as having been consumed.
Whether this happens because the vulture can’t find anything better
to eat or because this species considers vegetal matter to be a reasonable
food choice, consumed whenever it’s handy, I don’t know.
FEEDING METHODS – Turkey Vulture
Like all vultures, turkey vultures literally don’t know where
their next meal is coming from, so they need to eat as much as possible
whenever they find food. And wherever they find it. Vulture feet are
very different from the grasping raptorial toes of eagles and hawks.
Vultures by contrast have straight, relatively weak toes and blunt talons
that are designed to brace the birds as they pull at a carcass with
their beaks. Because they don't have strong, grasping toes, vultures
can’t carry food in their feet. They have to eat at the food source.
Turkey vultures typically feed on smaller carcasses than black vultures
do, and they eat differently. They are hierarchical feeders, eating
in turns with the alpha, dominant male going first. Lesser individuals
wait their turn without complaint. All eat as much as they can hold
(or as long as the food holds out), because they may have to feed young.
And since they can’t carry food back to the nesting site in their
feet, they’ll carry it in their crops and regurgitate it for the
hungry chicks.
FEEDING METHODS – Black Vulture
Black vultures specialize in eating larger carcasses than turkey vultures
do, and they may depend on numbers to open up something as big as a
pig or cow. The word vulture comes from the Latin word vellere,
which means “to tear.” And that’s exactly what black
vultures do. Their beak is not strongly compressed in a hook shape the
way an eagle’s beak is; consequently it lacks the tearing power
of a raptorial beak. Black vultures make up for this lack with quantity.
In the South, dozens of these birds will congregate at a carcass. Their
first move is to try to break into the body by entering through a natural
opening like the anus or an eye socket. If the skin is too thick to
allow that, the birds pull at the carcass in unison, tearing it in different
directions. Without plenty of partners to help open up the carcass,
black vultures may only be able to eat easily removed tissue such as
tongues and eyes.
The feet are used to brace the birds as they yank
at the carcass with their hooked beaks. The short tail is also used
as a brace, and may become quite worn-looking over time. Now the reason
that vultures have virtually bare heads and necks becomes clear. The
long neck emerges from the neck ruff and the head and neck are inserted
deep into the carcass. If they were thickly feathered, they would be
covered in hard-to-remove gore, not to mention bacteria. For purposes
of hygiene the neck and head are almost featherless.
HUNTING STRATEGIES – Turkey Vulture
There are seven species of vulture found in the New World and three
of them, including the turkey vulture, have evolved a well-developed
sense of smell to sniff out rotting meat. Old World vultures do not
do this. In fact, birds as a group do not have a good sense of smell,
and the exceptions to this general rule are few. The turkey vulture
and two close relatives (the lesser yellow-headed vulture and the greater
yellow-headed vulture) have now been proven to be among the exceptions
by researchers David Houston and Kenneth Stager. Until these men did
their field work, the idea that turkey vultures used olfaction (a sense
of smell) to find food was controversial. Particularly since no less
an authority than John James Audubon said it wasn’t so. Audubon
did some experimenting by putting smelly carcasses under cover and waiting
for turkey vultures to detect the meat by smell. When no vultures showed
up, he concluded that they couldn’t be finding their food by scenting
it out and published his conclusions in 1826.
The problem was that Audubon was apparently using
meat that was too rotten. It isn’t true that vultures will
eat any old thing. Turkey vultures in captivity eat fresh meat with
every evidence of enjoyment. Ecologist David Houston, working in the
tropics, hid chicken carcasses in varying stages of decay. His research
showed that turkey vultures cannot detect freshly-killed carcasses by
smell. By the second or third day, as the meat begins to rot, the birds
can and do find their way to the carcasses. However, by the fourth day,
when the chickens were in an advanced state of decay and therefore very
smelly, turkey vultures rarely showed any interest. Houston concluded
that by that point there would be such a high level of microtoxins present
in the putrescent meat that it would be dangerous to eat even for a
vulture.
Other researchers working with condors in Peru verify
the turkey vulture’s ability to sniff out hidden meat. Despite
the researchers’ attempts to hide carcasses meant for Andean condors,
the local turkey vultures always found the meat, often walking right
into the researchers’ camp to uncover the booty. Always the vultures
came from downwind.
This is not to say that turkey vultures hunt exclusively
by smell. They use an efficient combination of sight and smell. This
species typically soars about 200 feet in the air or even lower, cruising
just above the treetops. At that height the birds can scent out a carcass,
but not higher. On these searching flights the vultures are also using
their very sharp eyesight to spot food. Once it is sighted, another
vulture strategy comes into play. These birds watch each other as they
food-search. When food is sighted, the finder circles above it for some
time, alerting the other vultures in the vicinity to the presence of
a meal. When one bird drops down, they all drop.
Because the turkey vulture and its tropical relatives
the lesser and greater yellow-headed vultures are skillful at finding
food hidden by forest cover, the tropical rainforests of Central and
South America are well populated with vultures. The black vulture and
a huge and colorful species known as the king vulture lack a well-developed
sense of smell, but they’re very good at spotting turkey vultures
dropping down on a carcass. So five species of vultures live in the
rainforests of tropical America. Africa, by contrast, is devoid of vultures
in its forests, since no Old World vulture has evolved a good sense
of smell.
HUNTING STRATEGIES – Black Vulture
Black vultures do not have a well-developed olfactory sense, but their
eyesight is very keen. The birds watch each other as they soar, and
they also watch turkey vultures. Black vultures typically soar higher
than turkey vultures, but as soon as they see a vulture of any species
dropping purposefully, down they come. And they have no mercy on the
competition. Black vultures immediately shoulder the more timid turkey
vultures out of the way and take control of the carcass. They have even
been observed stealing tidbits right out from under the beak of a feeding
Andean condor. They may stake out a likely source of food, such as a
garbage dump or slaughterhouse, and keep it under constant watch. Once
food is located, black vultures circle above it for some time, apparently
to signal the find to others.
MIGRATION – Turkey Vulture
Turkey vultures from northern areas migrate, some traveling thousands
of miles to Central or South America. Others travel only as far as the
southeastern U.S. In New England both our resident turkey vultures and
those that breed farther north may be seen on migration. Fall migration
is relatively late, in October and November. Spring migration is from
February through May. Many of the turkey vultures seen during migration
are probably subadults, one-year-old birds that have not yet reached
breeding age. In Massachusetts Mt. Wachusett is a good observation point,
as is the Quabbin Reservoir. Based on personal observation, I think
that turkey vultures that nest in Massachusetts don’t really migrate.
These breeding adults simply wander southward during the coldest weather
in December, January and February. By late winter the birds are back,
and I now consider the first sighting of a returning turkey vulture
in March to be a sign that spring is on the way. During the particularly
mild winter of 2001-2002 turkey vultures in Massachusetts apparently
stayed put and could be seen soaring over the highways even in January
and February.
MIGRATION – Black Vulture
Black vultures are nonmigratory, although individuals wander. They have
been observed in Massachusetts in every month of the year.
RELATIONSHIPS – Turkey Vulture &
Black Vulture
Until recently, all the diurnal raptors were lumped together in one
huge, motley group called Falconiformes. Within this order ornithologists
recognized five smaller groups or families. These were: The seven New
World species of vultures, which included the turkey vulture and the
black vulture, as well as the California condor and the Andean condor;
eagles, hawks, kites and Old World vultures; falcons and caracaras,
which are long-legged, heavy-beaked birds found only in the New World;
the secretary bird, living only in Africa; and the osprey.
The family of New World vultures, which are quite
different in appearance and behavior from Old World vultures, were thought
to be only distantly related to the other diurnal birds of prey. But
some ornithologists doubted that there was any relationship. They pointed
out that there were many important similarities between New World vultures
and storks. From the structure of their thigh muscles, which is very
similar, to the fact that both groups are voiceless, to the tendency
of both groups to excrete on their legs, New World vultures and storks
seemed to have a great deal in common.
Now DNA analysis has proved what previously could
only be suspected: New World vultures are indeed closely related to
storks and not to raptors. As a consequence, the seven species of New
World vultures are now grouped with storks in a family called the Ciconiidae,
and the old order known as Falconiformes has been discarded. All the
diurnal raptors, from eagles to falcons to hawks to Old World vultures,
are now put in the order Ciconiiformes, along with New World vultures
and their relatives the storks. There are 25 other families in this
huge order, including shorebirds, herons and penguins.
VOCALIZATIONS
Birds don’t have a larynx as we do. Instead they have a syrinx,
or voice box, that uses airflow from the lungs to produce sound. Songbirds
that produce complex and varied calls have a wide range of specialized
muscles in their syrinxes. New World vultures, however lack these muscles
and are correspondingly voiceless. They cannot produce far-carrying
contact calls to mates or territorial calls to competitors. New World
vultures do produce some sounds, notably an emphatic hiss used as a
warning by all ages.
Turkey Vulture – This
species sometimes grunts. One researcher has noted that turkey vultures
can produce a loud growl resembling the sound made by some of the big
heron species. Both sounds are only audible close-up.
Black Vulture – This is
an aggressive species that often squabbles with other vultures over
feeding rights. Consequently it’s a bit more vocal than the turkey
vulture. It grunts and snarls when jockeying for position at a carcass.
The chicks produce a low “woof” when disturbed. At least
one reference book (Eagles, Hawks and Falcons
of the World by Brown and Amadon) says that “Adult
also utters a croaking ‘coo’ like a pigeon.” These
sounds can only be heard close-up.
SUNNING – Turkey Vulture & Black Vulture
Both Old World and New World vultures typically begin their day at a
roosting site by spreading both wings wide. Storks do this as well.
Researchers have pondered (and argued over) the reasons for this behavior
for decades. There is a consensus now that sunning serves several functions:
SELF-DEFENSE – Turkey Vulture
Turkey vultures have evolved a particularly repellant but extremely
efficient means of protecting themselves from predators. If they’re
agitated, they vomit the contents of their crop and stomach. The vomit
is projectile, meaning that it may be hurled some distance, and the
vultures can aim. Not only is the vomit putrid (consider what the birds
have been feeding on) but the mess regurgitated from the stomach will
contain acid, which will burn. If this appalling defense mechanism doesn’t
work, turkey vultures play dead.
SELF-DEFENSE – Black Vulture
Black vultures also projectile-vomit, but this is an aggressive species
that doesn’t hesitate to attack a would-be predator, hissing,
biting and flapping its large wings in the intruder’s face. Researchers
working with black vultures have learned to expect an assault when the
birds are cage-trapped for research. Turkey vultures, says David Kirk
(quoted in Vulture: Nature’s Ghastly Gourmet
by Wayne Grady) “are completely passive. When you go up to them
they just play possum.” If he cage-trapped both species together,
“When I went to take them out the turkey vultures would lie down
on the ground and the black vultures would climb up on their bodies
to get at me.”
UROHIDROSIS – Turkey Vulture & Black
Vulture
In the avian world, only storks and a few New World vultures have evolved
this method for cooling down. The word means to sweat by urination,
and turkey vultures and black vultures achieve this by excreting on
their legs. As the moisture in the excrement evaporates the bird is
cooled. Birds have no sweat glands and have evolved a variety of ways
to cool off. Urohidrosis is arguably the most grotesque.
Black vultures also excrete on their legs when they’re
agitated (presumably because stress raises their body temperature).
Researchers have learned the hard way that wild black vultures become
agitated when handled.
ROOSTING – Turkey Vulture
This species forms large communal roosts. After a day spent in food-searches
and feeding, turkey vultures return to the same roost for the night.
Large trees are the usual roosting site, but buildings and radio towers
may be used as well. Dozens of birds may occupy the site, which can
be used year after year. The birds don’t leave the area until
the sun is well up and thermals have begun to form. They leave individually.
Nesting areas are separate from roosting areas, but the communal roost
will be used throughout the breeding season by subadults too young to
breed.
ROOSTING – Black Vulture
Black vultures also form large communal roosts, and may roost with turkey
vultures. The roosts may contain thousands of individuals. Black vultures
leave the roosting area about an hour later than turkey vultures because
their heavier wing loading means they need more powerful thermals to
stay aloft. The birds leave the site in groups rather than individually,
as turkey vultures do.
BREEDING BEHAVIOR – Turkey Vulture
Turkey vultures are monogamous and mate for life. A small group may
indulge in a display dance on their nesting grounds.
BREEDING BEHAVIOR – Black Vulture
Black vultures have one mate at a time, but they may choose a new partner
the next breeding season. Group flying displays of circling and pursuit,
the males chasing the females, seem to be the norm. Then the ardent
couples drop to the ground and courting males display before the females
they hope to impress. They prance and wing-flap, then lower their heads
and give off, says Audubon, “a puffing sound, which is by no means
musical.”
NEST, EGGS AND YOUNG – Turkey Vulture
No New World vulture constructs a nest. Writing in Vulture: Nature’s
Ghastly Gourmet, Wayne Grady sums up the situation: “For
all vultures, the word ‘nest’ is always a verb, never a
noun.” Which means that while vultures certainly nest, they do
not make nests. Turkey vultures lay their eggs in rock caves or rock
falls on talus slopes, in a hollow stump or on the ground in dense cover.
The nesting area is quite separate from the roosting area and is located
in a remote, hilly place. Turkey vultures nest in pairs, not communally.
Usually two eggs are produced and they are laid directly
on the ground. No attempt is made to provide any padding or protection.
The eggs are typically positioned in an area of heavy shade, to prevent
them from addling while the parents are away on food-searches. Both
parents incubate the eggs, and a good thing, because the incubation
period is lengthy – 38 to 41 days. In Connecticut and Massachusetts
egg-laying gets underway in April or May.
The newly-hatched young are covered with a thick
coat of pure white down. Both parents brood and feed the growing youngsters.
The young develop slowly, which is the pattern with big birds. Fledging,
the ability to fly, doesn’t occur until the chicks are 11 weeks
old, and all that time the young turkey vultures depend upon their parents
for food. Since vultures cannot carry food in their feet as eagles and
hawks can, and don’t seem to like to carry it in their beaks (perhaps
rotting carrion falls apart too easily), they’ve evolved another
way to feed their young. They regurgitate partially digested food, which
the young birds eat by inserting their beaks into their parents’
mouths and slurping away. This method of feeding is messy and smelly,
and both the parents and the chicks will vomit if an intruder appears.
In consequence the nesting areas are extremely foul-smelling places.
I wonder, but cannot prove, if turkey vultures find their concealed
nests by each one’s individual odor.
Even after fledging, young turkey vultures remain
dependent upon their parents for food for several months. This long
dependency period means that this species only breeds every other year,
and typically two eggs are produced, rarely three. This slow reproductive
rate is one reason turkey vultures are declining in number.
NEST, EGGS AND YOUNG – Black Vulture
Black vultures are not nest builders any more than turkey vultures are.
Eggs are laid in hollow stumps or tree bases, in depressions under rocks,
in rock caves or in thick vegetation. In Central and South America the
species may nest fairly high up in the nooks and crannies of city buildings.
Good nesting sites, offering protection yet easy access, are limited,
so the nests of necessity may be fairly close together.
Two eggs, two days apart, are laid directly onto
the nest surface. Both parents incubate the eggs, which hatch in 32
to 39 days. The eggs will hatch in the order they were laid, and the
older chick may be significantly larger than its younger sibling for
a few weeks. In contrast to turkey vulture chicks, with their coats
of pure white down, the downy covering of black vulture chicks is cinnamon-pink.
Their vulturine faces peer from the thick wrapping of down like heads
of nightmarish puppets plunked onto teddy bear bodies. These are not
cute babies.
After the chicks hatch, they are brooded for about
five days by both parents. When the chicks can regulate their own body
temperature and can be safely left behind, the parents spend most of
the day in food-searching. Like turkey vultures, black vultures carry
food back to their nests in their crops and regurgitate it for their
chicks. The young are fed three times a day. They take 10 to 11 weeks
to fledge and are fed by the parents for several months after that.
STATUS – Turkey Vulture
Turkey vultures have expanded their range northward in the last century.
At the same time they have been declining in number in the South, where
historically they have been most numerous. One reason is their slow
rate of reproduction juxtaposed with the increasing hazards of the modern
world. Habitat loss is a huge problem, as suitable roosting and nesting
sites are taken over for human development.
Human persecution, while now illegal, in the past
destroyed large numbers of turkey vultures. It was thought that the
birds spread livestock diseases. They do not; turkey vultures actually
help to prevent the spread of disease. Writes Wayne Grady in Vulture:
Nature’s Ghastly Gourmet: “The acid
in a vulture’s digestive tract is so strong that botulism and
cholera bacteria that would wipe out whole villages pass through a vulture
like milk through a baby, and studies of vulture excrement show that
they actually help control serious outbreaks of anthrax in cattle and
swine when they eat infected carcasses; their stomachs destroy the bacteria
that cause the diseases.”
Vultures deserve our protection, for their own interesting
sakes as much as for any good they might do us, and in fact they are
protected by law from shooting or harassment. Despite this turkey vultures
are decreasing, and have been placed on the Audubon Society Blue List,
indicating that the species’ status is being carefully watched.
STATUS – Black Vulture
Like the turkey vulture, the black vulture has been unfairly persecuted
as a spreader of disease. This is still a common species over its range,
but it has declined in the Southeast due in large part to loss of good
nesting habitat. Timber management removes old trees that might offer
hollow snags and stumps. Abandoned buildings that were not uncommon
in the Depression years are now hard to find as well, with the result
that the black vulture is often forced to nest in dense vegetation,
where the eggs and chicks are vulnerable to predation.