White
Handed Gibbon
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primata
Family: Hylobatidae (tree dweller)
Genus: Hylobates
Species:Hylobates lar
Features:
The
White-handed gibbon, like the gorilla, chimpanzee and orangutan, is
an ape, not a monkey. They share with the great apes (gorilla,
orangutan and chimpanzees) several features: a large brain, a flat
face with shortened jaws, a more or less upright posture, a broad
chest and no tail. Ischial callosities
are present.
Gibbons are very small and lightweight. They have a small, round
head, very long arms (the arms are longer than the legs), and a
short, slender body. Gibbons have lightweight bones.
The long forearms
which assist it in
suspensory
behavior.
Gibbons are
arboreal; they spend most of their lives in trees.
Gibbons are covered with light-colored to very dark brown ( or
black) dense hair on most of their body (except their face, fingers,
palms, armpits, and bottoms of their feet). Fur is
extremely dense, providing protection from rain. One square
centimeter of skin has over 2,000 individual hairs (13,125 per sq.
in.) compared to 900 hairs per sq. cm. for Old World monkeys.
Some
species of gibbons have a white face ring, a band of white face
completely surrounding their jet-black face.Snout is not
protruding; nostrils are more widely spaced and more lateral than
Old World Monkeys. Small jaws with long canine teeth.
Gibbons have senses very similar to ours, including hearing, sight
(including color vision), smell, taste, and touch.
Gibbons' hands are very much like ours; they have four long fingers
plus a smaller opposable thumb. Their feet have five toes, including
an opposable big toe. Gibbons can grasp and carry things with both
their hands and their feet. When they swing through the trees
(called brachiating), they use four fingers of their hands like a
hook (but they do not use the thumb for this). Thumb is used for
climbing tree trunks and thick branches and for manipulation of food
and grooming. The upper sides of hand and feet are always white
(‘white-handed’), contrast is less apparent in the buff specimens.
The average body mass for an adult male white-handed gibbon is
around 5.7 kilograms, and for the female it is around 5.3 kilograms.
Male gibbons are slightly larger than the females. Males are about 3
ft (90 cm) long and weigh about 15 pounds (7 kg).
The white handed gibbon has throat sac located beneath the chin to
help enhance the calls. Male song is simple
with quaver-hoots, female song is longer, rising to climax, about 18
seconds long.
Location:
The white-handed gibbon is found in
different parts of
southeast Asia, the countries of Burma, China, Indonesia, Malaysia,
North Sumatra, and Thailand. This species is found in
old growth tropical rain forests, semideciduous monsoon forests and tropical
evergreen forests. They prefer the covered closed canopy but during
feeding may climb to highest emergent crowns of trees or descend to
clumps of bamboo and low bushes, or to drink.
Food:
The
lar gibbon is one of the pickiest eaters in the primate world.
The white-handed gibbons
are mainly frugivores,
preferring fruits high in sugar such as figs. Gibbons are omnivores (eating plants and meat). They forage
for food in the forests during the day, eating fruit, and they
may visit 16 or more widely spaced food trees in a day's foraging.
About 75% of their diet is fruit, but they
also eat leaves, flowers, seeds, tree
bark, and tender plant shoots. Sometimes they also eat insects, spiders,
snails, bird
eggs, and small birds.
Zoo diet is primate chow, fruits,
vegetables and browse.
Gibbons drink water, often by dipping a furry hand into the water or
rubbing a hand on wet leaves, and then slurping up the water from
their fur. Gibbons sometimes do this while dangling above the water
from a thin tree branch. They drink by licking their own fur after a
storm, or dipping an arm into a tree hole or rubbing it on wet
foliage.
They
have several adaptations for feeding. One of them is brachiating
locomotion, which involves swinging from branch to branch by their
arms. This style of motion allows them to reach the edge of the
tree canopy, where most of their food is found. Other adaptations
include high cusps on their back teeth to help grind plant matter,
and a gut adapted for a folivorous diet.
Social:
Gibbons are social animals that are active during the day (they are
diurnal).
Gibbons mate for life; the young, born singly, remain with the
family group until they are five or six years old.
Like other apes, gibbons groom one another (they clean the hair of a
family member).
The males are
not socially or physically dominant over females. They are
vigorously territorial, spending up to 1/2 hour or more each morning
calling and displaying. The function of calling seems to be both
territorial and to reinforce the pair bond. The calling bout is
usually initiated by the female. Male and female "duet" with
different "songs." The female song is a plaintive swooping call,
rising to a crescendo - her great call; the male calls with a
high-pitched "quaver song."
The male usually
takes the lead in attacking other gibbons encountered, although
they rarely actual fight.
Playful ‘biting’ matches, which can be painful to a human, seem to
determine rank order of mature juveniles within the group. Even
serious bites don't seem to hurt them because of their dense fur.
Female gibbons carefully nurture their young. Eyes are open at birth
and body and limbs are bare; very dependent on their mother for
warmth. Many are white at birth and do not become black or final
color until 2 – 4 years old. Babies can grasp their mother's fur to
cling to the mother's belly soon after birth.
Infants are
hairless except for a cap of fur on the crown.
Babies usually have light hair at first and darker hair develops as
they grow older. They
are weaned at about 1 year old. Young gibbons stay with their mother
for about 6 years. The young then venture out (or are forced out) to start a new family group of their own.
Movement:
Gibbons are extremely acrobatic and agile. They spend most of their
life in the trees. They move by swinging gracefully from branches
and vines; this is called brachiating. When they brachiate,
they use four fingers of their hands like a hook (but not the
thumb). They swing from branch to branch (horizontally or
vertically), with legs flexed under body; using arms alternately and
keeping hand bent in hook shape, and movements appear effortless.
They are able to change direction even during fastest bounding by
slightly touching a branch. While swinging, they are able to catch
birds out of the air and eat them after landing.
They can also walk along
small branches high up in the air,
like tightrope walkers; they use outstretched arms to help keep
their balance. Gibbons
climb when moving slowly and feeding. Gibbons can also leap acrobatically across large gaps
in the tree canopy from tree branch to tree branch; gibbons have
been known to leap over 30 feet (9 m) in a single jump. The gibbon
is the only anthropoid ape to walk on its hind limbs only, usually
raising its arms for balance.
Gibbons cannot swim and avoid the water. When on the ground (which
is rare), gibbons walk bipedally (on two legs).
These are the most active of all gibbons. They move faster, more quietly, and
farther each day than any other forest apes or monkeys. Brachiation
comprises 90% of locomotor activity. Adaptations include precision of
movement, incredible eye-hand coordination and dexterity. This
remarkable agility makes a healthy adult gibbon virtually
invulnerable to predation. They sleep sitting on their ischial
callosities, hands resting upon flexed knees and head buried between
knees and chest.
Territories:
Each
family defends its territory by song and threat display. Gibbons are
very territorial. A pair maintains and defends a territory through a
series of calls and vocalizations. They also use an elaborate system
of calls to keep track of family members within the territory.
Communication:
The
white-handed gibbon is distinguished by its musical howl. They are
quiet during the day but commonly howl at sunrise and sunset. They
are very vocal, making loud "whoop" sounds. Their loud
resonant songs can be heard up to 1/2 mile away. Songs by far excel
those of all other species because of a sound-amplifying throat sac.
Duetting is the singing
between the male and female, and is dominated by the female. This helps to maintain
the pair bond between the pair and to
maintain the territory.
Each morning upon awakening a family group of gibbons loudly
announces its presence in the forest, using a territorial hooting
call and menacing gestures. This call warns other gibbons to stay
out of their territory (and especially away from the local fruit
trees). This noisy display takes 1/2 hour or more every morning and
is usually started by the adult female. The male and female have
different calls.
In
friendly greetings, corners of mouth are drawn back, revealing
teeth, and tongue is sometimes protruding. In anger, mouth is opened
and closed repeatedly, smacking lips and snapping teeth together.
Snarling is interpreted as an intention of biting.
There are 9 species with 9 different territorial songs. The
gibbons seem to be born knowing the songs because they are always
the same, and not
learned.
Habits:
Gibbons do social
grooming, when one individual grooms another, to reinforce the bonds between individuals.
They do not construct sleeping nests but show preference for
specific ‘sleeping trees’ where no other
family group is tolerated. They sleep sitting erect in trees,
huddled together in twos and threes, with knees bent up to chin,
hands folded on knees and face buried between the knees and chest. They sleep sitting upright, resting on tough pads
located on their rear ends (these pads are called ischial
callosities).
Status: endangered
This
species is threatened for a several reasons. These gibbons are
hunted for meat in some areas. Live capture for the pet trade also
poses a serious problem. In many Asian countries, it is
"fashionable" to own your own primate, and this has led to the death
of many gibbons either at the time of capture or during transport.
The final, and greatest, threat to the gibbon is deforestation.
Rainforests are disappearing at an alarming rate due to logging and
agricultural, leaving forest species with an ever smaller region in
which to live. Some efforts are being made to save these primates,
such as national parks and reserves, but they are not very
effective. Laws protect them from live capture, but they are rarely
enforced.
Gibbon populations are decreasing; they are threatened with
extinction. There are estimated to be about 79,000 lar gibbons (the white-handed
or common gibbon). Lar gibbons retain only 10% of their original habitat in protected
reserves. In 1987, the IUCN estimated that there were 79,000 lar
gibbons but to protect the more endangered species, all are listed
as endangered by the USDI (1980) and are on appendix 1 of the CITES,
prohibiting commercial trade in gibbons. They
are endangered and participate in the Species Survival Plan.
Life span is 30
to 40 years.
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