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Spider Monkey
Cebidae Ateles
Geoffroyi geoffroyi
ORDER: Primate
FAMILY: Cebidae
GENUS: Ateles
SPECIES: geoffryi
Features:
The
spider monkey is considered a primitive new world monkey. They are
called spider monkeys because they look like spiders when they are suspended by their
tails.
Spider
monkeys are usually all black, but some have flesh coloured rings
around their eyes and white chin whiskers. Hair generally
coarse and stringy. Lacks underfur.
Colors: golden, red, buff, brown or black, with hands and feet
generally black.
Their brains are less complex, their thumbs are not opposable and
their nostrils are further apart. These monkeys depend highly on
their keen binocular vision. They have slender bodies and limbs with
long narrow hands.
This arboreal monkey has a prehensile tail that is muscular and
tactile and is used as an extra hand. The tail is sometimes longer
than the body. Both the underside and tip of the tail are used for
climbing and grasping and so the spider monkey uses it like a fifth
hand. When swinging by the tail, the hands are free to gather food.
The
spider monkey's arms and legs are particularly long too. It has
hooked-shaped hands because its thumbs are either absent or reduced
to a stump. Hands are like hooks with long, narrow palms, long
curved fingers, and no thumb. Head is small, muzzle prominent.
Thumbs on feet only.
Male
body length 38-48cm, tail 63-82cm, 9-10kgs. Female body length
42-57cm, tail 75-92cm, 6-8kgs. Males and females look the same.
Location:
Spider monkeys are generally found in lowland rain forests from
Mexico to South America, along the coasts and the banks of the
Amazon, south to Bolivia and the Matto Grosso in Brazil, and the mountain forest slopes of the Andes. They are
restricted to arboreal habitats, mainly in the top of the tree
canopy. They range from sea level to higher ground.
Spider monkeys live in evergreen rainforests, semi
deciduous and mangrove forests, lowland rainforests to mountain
forests. In these forests they live mostly in the upper canopy,
preferring undisturbed high forest, almost never coming to the
ground. They prefer wet
than dry forests.
Food:
Spider monkeys are frugivores preferring a diet of 90% fruit and
seeds, feeding on the mature soft parts of a wide variety of fruits
in which the seeds are swallowed along with the fruit. They also eat
young leaves, flowers, aerial roots, sometimes bark and decaying
wood, as well as honey. A very small part of the diet consists of
insects, insect larvae and birds’ eggs. When feeding, they may hang
by their tails and reach out for tidbits with their hands. They can
also pick up things with their tails. They eat large quantities of
food over a relatively short period of time and they tend to feed by
suspension while hanging, climbing or moving. They do not pick fruit
and carry it to another location to be eaten.
The
lead female is often observed determining the forage route for the
group; however if food is scarce they tend to divide into smaller
groups. The largest groups of monkeys, sometimes up to 100 monkeys, are
found in a big tree loaded with fruits. When they
feed in a large tree, spider monkeys continuously adjust their
positions so they are not too close to one another. Latecomers wait
until earlier arrivals leave before entering the tree. It seems that
spider monkeys can be quarrelsome feeders if they are too close to
one another, and this spacing out saves them all trouble. During
those months of the year when they have to depend on small,
scattered sources of fruit, such as from palm trees, lone
individuals and smaller aggregations are found moving through the
forest. Thus, they avoid quarrelling at food sources with only
enough ripe fruit at any one time to feed a few monkeys.
In
the Zoo they are fed celery, bananas, raisins, apples, oranges,
carrots, monkey chow, dog chow, lettuce, and wheat bread.
Social:
Spider monkeys live in medium-sized, loosely associated groups of
about 30 individuals. The females have a more active leading role
than males, so their social system is thought to be matriarchal.
Within the group, adult males can coexist peacefully, although there
is a clear hierarchy determined by age. The group is centered on the
females and their young. Males are dominant over females, but it is
the females that make the key decisions for the group. Males may
forage in small groups. Females and offspring often forage alone.
When threatened, they make barking noises, but if that doesn’t scare
intruders away, they fragment into subgroups and run. They prefer
retreat, so fights are rare .
Every 2 – 3 years, a mother will give birth to one entirely
black baby. No
one else besides the mother looks after the baby. The baby is
continuously carried by the mother, clinging to her and at about 5
months of age it will begin riding on her back, wrapping its tail
around the mother's tail for additional security. It will be
dependent on its mother's milk for 2 years. Juveniles at the age of
24 to 50 months old never ride on their mother's back but they will
still stay close to her. They spend their time exploring, or
chasing, grappling, and jumping on others. They will play with
others their same age or with adults.
Movement:
Spider monkeys have been called "the supreme acrobat of the forest."
In the wild, the Spider monkey rarely comes down to the jungle
floor. Acrobatic and swift, Spider monkeys move through the trees,
with one arm stride covering up to 40 feet.
Spider monkeys are characterized by their long, slender limbs and
great agility. They travel in small bands in forest trees, moving
swiftly by making tremendous leaps, sprawling out like spiders, and
grasping tree limbs with their prehensile tails.
Its
tail and supple shoulder joints allows
it to swing quickly under branches (brachiate) without fear of
snagging thumbs. Its feet are greatly elongated and their big toe is
prehensile, working like hands to grasp thinner branches, as well as
for better grip as it walks upright on two legs on broad branches.
It may even stand upright on a branch using its tail as a third limb
in a tripod arrangement with its two legs! When the animal is on the
lookout, it stands or walks on two feet, using the tail to hold on
to a support.
Spider monkeys use several
different types of locomotion: quadrupedal, using all four limbs for
locomotion as seen while walking or running; suspensory locomotion
used when hanging, climbing or moving through the trees and
bipedalism, using only two limbs when leaping. Quadrupedal
locomotion is usually observed if the monkey is on a stable
relatively substrate free of obstacles. When they are using
suspensory locomotion they may be brachiating (swinging with their
arms from one branch to another while often maintaining a tail
hold). The most commonly used pattern of body movement while in a
feeding pattern is that of quadrupedal, climbing and suspensory
locomotion. While traveling they mostly employ quadrupedal walking
and running, suspensory locomotion and climbing.
Spider monkeys brachiate swiftly through the canopy, but not as well
as gibbons of Asia. Where possible, they prefer to scuttle on all
fives (including the tail!) over branches. They may also leap
between trees and branches. On the rare occasions when they move on
the ground, they may walk upright on two legs, their long tails held
stiffly upright against the back.
Territories:
Groups defend their ranges. Males will mark their territory with
secretions from chest glands. Anyone stumbling into spider monkey
territory receives an unpleasant ‘welcome’ of screams, barks, and
rattling branches and thrown branches or feces. The interactions
will often begin with males, often along with one or two females,
calling, which will bring other group members into the area.
When
males are within 100m of each other, they will mutually threaten
with a great deal of bluster. They chase about in the trees, shaking
branches and whoop and growl at each other. These noisy sessions can
easily last for an hour or more but they seem to be strictly male
affairs; females remain quietly in the background. But troops rarely
come to blows. Sometimes a male will occasionally scent mark
branches by smearing saliva and a
secretion that comes from a gland on his chest onto the branches,
presumably to deposit his scent in the area.
Communication:
These monkeys have a variety of loud calls, audible for 800-1000m on
the ground and 2,000m above the canopy. These "long" calls are used
to help the groups space out in the forest and avoid unnecessary
confrontations.
These calls are also used to alert members of a group to a
central feeding site. Juveniles develop their long call by trial and
error.
When they spot a predator on the ground, both males and
females make a loud "ook-brak" bark, while throwing branches
and shaking tree limbs by jumping up and down. Only males whoop. But
when this fails to scare off the intruder, they scatter in smaller
groups. The most
frequently heard call resembles whinnying of a horse - probably a
greeting or contact call. Like other primates, they have a wide
range of facial gestures to express their moods. Both genders sniff
and embrace when greeting.
Habits:
The
spider monkey travels in groups and the route they take through
trees remain constant. During more abundant times of the year, the
route shortens but does not change.
Spider monkeys are diurnal, which means they are active during the
day. They
are most active in the early morning. Feeding bouts are 1-15 minutes
long.
At night they use sleeping trees which are
usually tall enough so that the crown is free from the canopy
beneath it having a broad open crown that has horizontally forked
branches for prolonged resting postures. The sleeping trees are
often chosen for their ability to provide a ready source of food.
Sleeping high in a tree above the canopy also affords security from
predators.
Since the thumb is absent, the Spider monkey's grooming is not as
developed as in other primates. They scratch themselves with hands
and feet, but most of their social grooming is mothers grooming
their young.
Status:
Critically Endangered
Their lifespan in the wild is about 27 years. Average 20 years in
the wild, 33 years in captivity.
The
spider monkey is critically endangered, which means it is facing an
extremely high risk of extinction in the wild in the immediate
future.
Considered good to eat and because of their large body size, spider
monkeys have been severely hunted throughout their range. They are
easy to locate because they are noisy and travel in big groups. So
spider monkeys are often extinct in areas easily accessible to
people. There is also a lucrative pet trade. They are also
affected by habitat destruction, particularly logging, which removes
the tall trees that they depend upon.
They
are also vulnerable because they have low maturation and
reproduction rates.
Three of the spider monkey species, the white-bellied spider monkey,
brown-headed spider monkey, and white- whiskered spider monkey are
listed as Endangered by either USESA or IUCN. This means that these
species have at least a 20% chance of going extinct in the wild
within 20 years or 5 of their generations. The black-handed and
black spider monkeys are listed as Vulnerable by IUCN - there is at
least a 10% probability of extinction within 100 years. Only the
black-faced black spider monkey is considered at Lower Risk (CITES
II.)
The population is estimated at 2,000 in isolated pockets. |
