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SUMATRAN
ORANGUTANS
The
Sumatran Orangutan (Pongo abelii) is the rarer of the
two species of orangutans. Living and endemic to Sumatra
island of Indonesia, they are smaller than the Bornean
Orangutan. The Sumatran Orangutan grows to about 4.6
feet tall and 200 pounds in males. Females are smaller,
averaging 3 feet and 100 pounds.
Compared to the Bornean Orangutan, the Sumatran
Orangutans possess a lighter and longer pelage, a longer
face, a smaller stature, and flanges that are covered in
small white hairs.
Compared to the Bornean Orangutan, the Sumatran
Orangutan tends to be more frugivorous and especially
insectivorous.Preferred fruits include figs and
jackfruits. It also will eat bird eggs and small
vertebrates. The Sumatran Orangutans spend far less time
feeding on the inner bark of trees.
Wild Sumatran Orangutans in the Suaq Balimbing swamp
have been observed using tools. An orangutan will break
off a tree branch that's about a foot long, snap off the
twigs and fray one end. It then will use the stick to
dig in tree holes for termites. They'll also use the
stick to poke a bees nest wall, move it around and catch
the honey. In addition, orangutans use tools to eat
fruit. When the fruit of the Neesia tree ripens, its
hard, ridged husk softens until it falls open. Inside
are seeds that the orangutans love, but they are
surrounded by fiberglass-like hairs that are painful if
eaten. A Neesia-eating orangutan will select a five-inch
stick, strip off its bark, and then carefully collect
the hairs with it. Once the fruit is safe, the ape will
eat the seeds using the stick or its fingers. Although
similar swamps can be found in Borneo, wild Bornean
Orangutans have not been seen using these types of
tools.
NHNZ filmed the Sumatran Orangutan for its show Wild
Asia: In the Realm of the Red Ape; it showed one of them
using a simple tool, a twig, to pry food from difficult
places. There is also a sequence of an animal using a
large leaf as an umbrella in a tropical rainstorm.
The Sumatran Orangutan is also more arboreal than its
Bornean cousin; this could be because of the presence of
large predators like the Sumatran Tiger. It moves
through the trees by brachiation.
The Sumatran Orangutan is more social than its Bornean
counterpart. Groups of these orangutans gather to feed
on the mass amount of fruiting on the fig trees. However
adult males generally avoid contact with other adult
males. Rape is common among orangutans. Sub-adult males
will try to mate with any female, though they probably
mostly fail to impregnate them since mature females are
easily capable of fending them off. Mature females
prefer to mate with mature males.
Interval birth rates for Sumatran Orangutan were longer
than the Bornean ones and are the longest reported
interval birth rates among the great apes. Sumatran
orangutans give birth when they are about 15 years old.
Infant orangutans will stay close to their mother for up
to three years. Even after that, the young will still
associate with their mother.
Both orangutan species are likely to live several
decades; the longevity estimate can span for more than
50 years, with the oldest captive orangutan, Ah Meng,
being born in 1960.[6] Nonja, thought to be the world's
oldest in captivity or the wild at the time of its
death, died at the Miami MetroZoo at the age of 55.
The average of the first reproduction of P. abelii is
around 12.3 years old with no indication of menopause.
In 2002, the World Conservation Union put the species on
the IUCN Red List with critically endangered status. A
survey in the Lake Toba forests, found only two habited
areas, Bukit Lawang (defined as the animal sanctuary)
and Gunung Leuser National Park.The survey estimated
only 3,500 orangutans still live on Sumatra in 2002.
Baby orangutans are often captured and sold as highly
prized pets. In order to catch the babies poachers
normally have to kill the mother first to prevent her
from protecting her baby. |
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