are one of two endangered species
of great apes
(the other being the
). Known for their intelligence, they
live in trees and are the largest living arboreal
animal. They have longer arms than other
great apes, and their hair is typically reddish-brown, instead of
the brown or black hair typical of other great apes. Native to Indonesia and Malaysia, they are
currently found only in rainforests on
the islands of Borneo and Sumatra, though
fossils have been found in Java, the
Thai-Malay Peninsula, Vietnam and China.
only two surviving species in the genus
Pongo: the Bornean Pongo pygmaeus and the
critically endangered Sumatran Pongo
The subfamily Ponginae
includes the extinct genera Gigantopithecus
Ecology and appearance
Adult female orangutan
Size relative to a 6 foot (1.8 m)
An orangutan's standing height averages from and weighs between .
Males can weigh up to or more. Orangutan hands are similar to
humans hands; they have four long fingers and an opposable thumb
. Their feet have four long
toes and an opposable big toe. Orangutans can grasp things with
both their hands and their feet. The largest males have an arm span
of about .
Orangutans have a large, bulky body, a thick neck, very long,
strong arms, short, bowed legs, and no tail. They are mostly
covered with long reddish-brown hair, although this differs between
the species: Sumatran Orangutans have a more sparse and lighter
The orangutan has a large head with a prominent mouth area. Adult
males have large cheek flaps (which get larger as the ape ages)
that show their dominance to other males and their readiness to
mate to other females. The age of maturity for females is
approximately 12 years. Orangutans may live for about 50 years in
the wild. However, thousands of orangutans don't reach adulthood
due to human disruption. Orangutans are killed for food while
others are killed because of disruption in people's property.
Mother orangutans are killed so their infants can be sold as pets.
Many of the infants die without the help of their mother.
Orangutans are the most arboreal
great apes, spending nearly all of their time in the trees. Every
night they fashion sleeping nests from branches and foliage. They
are more solitary than other apes; males and females generally come
together only to mate. Mothers stay with their babies for six or
seven years. There is significant sexual dimorphism
: females can grow to
around 2 in or 127 cm and weigh around while flanged adult males
can reach 5 ft 9 in or 175 cm in height and weigh over .
The arms of orangutans are twice as long as their legs. Much of the
arm's length has to do with the length of the radius
and the ulna
than the humerus
. Their fingers and toes are
curved, allowing them to better grip onto branches. Orangutans have
less restriction in the movements of their legs than humans and
other primates, due to the lack of a hip joint ligament which keeps
held into the pelvis. Unlike
gorillas and chimpanzees, orangutans are not true knuckle-walkers,
and are instead fist-walkers.
Flanged adult male
makes up 65–90 percent of the orangutan
diet. Fruits with sugary or fatty pulp are favored. Ficus
fruits are commonly eaten, because they are easy
to harvest and digest. Lowland Dipterocarp
forests are preferred by orangutans
because of their plentiful fruit; the same forests provide
excellent timber for the logging industry and good soil conditions
for palm oil plantations. Bornean orangutans consume at least 317
different food items that include: young leaves, shoots, bark,
insects, honey, and bird eggs.
Orangutans are opportunistic foragers, and their diets vary
markedly from month to month. Bark is eaten as a last resort in
times of food scarcity; fruits are always more popular
Orangutans are thought to be the sole fruit disperser for some
plant species including the climber species Strychnos ignatii
which contains the
toxic alkaloid strychnine
. It does not appear to have any effect
on orangutans except for excessive saliva
, the practice of eating soil or
rock, has been observed in orangutans. There are three main reasons
for this dietary behavior; for the addition of minerals nutrients
to their diet; for the ingestion of clay minerals that can absorb
toxic substances; or to treat a disorder such as diarrhea.
Orangutans use plants of the genus Commelina
as an anti-inflammatory balm.
Behavior and language
Like the other great apes, orangutans are remarkably intelligent.
Although tool use among chimpanzees
documented by Jane Goodall
1960s, it was not until the mid-1990s that one population of
orangutans was found to use feeding tools regularly. A 2003 paper
in the journal Science
described the evidence for distinct
According to research psychologist Robert Deaner and his
colleagues, orangutans are the world's most intelligent animal
other than humans, with higher learning and problem solving ability
than chimpanzees, which were previously considered to have greater
abilities. A study of orangutans by Carel van Schaik, a
Dutch primatologist at Duke University, found them capable of tasks well beyond
chimpanzees’ abilities — such as using leaves to make rain hats and
leakproof roofs over their sleeping nests.
He also found
that, in some food-rich areas, the creatures had developed a
complex culture in which adults would teach youngsters how to make
tools and find food.
A two-week old orangutan
A two year study of orangutan symbolic capability was conducted
from 1973-1975 by Gary L. Shapiro with Aazk
juvenile female orangutan at the Fresno City Zoo (now Chaffee Zoo)
in Fresno, California. The study employed the techniques of
who used plastic tokens
to teach the chimpanzee, Sarah
linguistic skills. Shapiro continued to examine the linguistic
and learning abilities of ex-captive orangutans in Tanjung Puting
National Park, in Indonesian Borneo, between 1978 and
During that time, Shapiro instructed ex-captive
orangutans in the acquisition and use of signs following the
techniques of R. Allen and Beatrix Gardner who taught the
, in the
late-1960s. In the only signing study ever conducted in a great
ape's natural environment, Shapiro home-reared Princess, a juvenile
female who learned nearly 40 signs (according to the criteria of
sign acquisition used by Francine Patterson with Koko
, the gorilla) and trained Rinnie
, a free-ranging adult female orangutan who
learned nearly 30 signs over a two year period. For his
dissertationstudy, Shapiro examined the factors influencing sign
learning by four juvenile orangutans over a 15-month period.
The first orangutan language study program, directed by Dr.
, was listed by
in 1988. The Orangutan language
project at the Smithsonian National Zoo in Washington, D.C., uses a computer system originally developed at
UCLA by Neago in conjunction with IBM.
Zoo Atlanta has a touch screen computer where their two Sumatran
Orangutans play games. Scientists hope that the data they collect
from this will help researchers learn about socializing patterns,
such as whether they mimic others or learn behavior from trial and
error, and hope the data can point to new conservation
study of two orangutans at the Leipzig Zoo showed that orangutans are the first non-human
species documented to use 'calculated reciprocity' which involves
weighing the costs and benefits of gift exchanges and keeping track
of these over time.
Although orangutans are generally passive, aggression toward other
orangutans is very common; they are solitary animals and can be
fiercely territorial. Immature males will try to mate with any
female, and may succeed in forcibly copulating with her if she is
also immature and not strong enough to fend him off. Mature females
easily fend off their immature suitors, preferring to mate with a
Orangutans do not swim. At least one population at a conservation
refuge on Kaja island in Borneo have been photographed wading in
Orangutans, along with Chimpanzees
, and other apes, have even shown
laughter-like vocalizations in response to physical contact, such
as wrestling, play chasing, or tickling.
The populations on the two islands were classified as subspecies
until recently, when they were
elevated to full specific level, and the three distinct populations
on Borneo were elevated to subspecies. The population currently
listed as P. p. wurmbii
may be closer to the Sumatran
Orangutan than the Bornean Orangutan. If confirmed, abelii
would be a subspecies of P. wurmbii
Regardless, the type
has not been established beyond
doubts, and may be from the population currently listed as
(in which case wurmbii
would be a
while one of the names currently considered a junior synonym of
would take precedence for the northwest Bornean
). To further confuse, the name
, as well as various junior synonyms that have been
suggested, have been considered likely to all be junior synonyms of
the population listed as pygmaeus
in the above, thus
leaving the east Bornean populations unnamed.
In addition, a fossil species, P.
, is known from Vietnam, and multiple fossil
subspecies have been described from several parts of southeastern
Asia. It is unclear if these belong to P. pygmaeus
or, in fact, represent distinct species.
The Sumatran species is critically endangered
Bornean species of orangutans is endangered
according to the IUCN Red List
, and both are listed on Appendix I of
.The total number of Bornean orangutans
is estimated to be less than 14 percent of what it was in the
recent past (from around 10,000 years ago until the middle of the
twentieth century) and this sharp decline has occurred mostly over
the past few decades due to human activities and development.
distribution is now highly patchy throughout Borneo: it is
apparently absent or uncommon in the south-east of the island, as
well as in the forests between the Rejang
River in central Sarawak and the
Padas River in western Sabah (including
the Sultanate of Brunei).
largest remaining population is found in the forest around the
River, but this environment is at risk.
development have been observed for the Sumatran orangutans.
The most recent estimate for the Sumatran Orangutan is around 7,300
individuals in the wild while the Bornean Orangutan population is
estimated at between 45,000 and 69,000. These estimates were
obtained between 2000 and 2003. Since recent trends are steeply
down in most places due to logging and burning, it is forecast that
the current numbers are below these figures.
Orangutan habitat destruction
due to logging
and forest fires
, as well as
fragmentation by roads, has been increasing rapidly in the last
decade. A major factor in that period of time has been the
conversion of vast areas of tropical
to oil palm plantations
in response to international demand
(the palm oil
is used for cooking,
cosmetics, mechanics, and more recently as source of biodiesel
). Some UN
believe that these plantations could lead to irreparable damage to
orangutan habitat by the year 2012. Some of this activity is
illegal, occurring in national parks that are officially off limits
to loggers, miners and plantation development. There is also a
major problem with hunting and illegal pet trade. In early 2004 about
100 individuals of Bornean origin were confiscated in Thailand and 50 of them were returned to Kalimantan in 2006.
Bornean orangutan orphans who were confiscated by local authorities
have been entrusted to different orphanages in both Malaysia and
Indonesia. They are in the process of being rehabilitated into the
conservation centres in Indonesia include those at Tanjung Puting
National Park and Sebangau National Park in Central
Kalimantan, Kutai in East
Palung National Park in West Kalimantan, and Bukit Lawang in
Leuser National Park on the border of Aceh and North Sumatra. In Malaysia, conservation areas include
Semenggoh Wildlife Centre
in Sarawak and Matang
Wildlife Centre also in Sarawak, and the Sepilok Orang Utan Sanctuary near Sandakan in Sabah.
- Matt Walker Wild orangutans treat pain with natural
anti-inflammatory New Scientist 28 July 2008.
- Humans aren’t alone in giving gifts.
- Swimming orangutans’ spearfishing exploits amaze
the wildlife experts.
- Chimps, Other Apes Laugh Like People
Discovery channel, Jennifer Viegas'
interview with study project leader Marina Davila Ross }}
- Bradon-Jones, D., A. A. Eudey, T. Geissmann, C. P. Groves, D.
J. Melnick, J. C. Morales, M. Shekelle, and C. B. Stewart. 2004.
Asian primate classification. International Journal of
Primatology. 23: 97-164.
- Density and population estimate of gibbons
(Hylobates albibarbis) in the Sabangau catchment, Central
- The oil for ape scandal.