Pongo pygmaeus and Pongo abelii - Orangutan

Pongo pygmaeus and Pongo abelii - Orangutan

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Bornean orangutan






















I pose



Pongo pygmaeus (Bornean Orangutan)



Pongo abelii (Sumatran orangutan)

Common name

: orangutan


  • Length: max 1.5 m with an arm span that can reach 2.5 m
  • Weight: female 36 - 50 kg; male: 60-90 kg
  • Lifespan: 35 - 45 years even if in captivity it has been seen that they can live up to 60 years
  • Sexual maturity: female 7 years; male: 10-15 years


The Orangutan, belonging to the Pongo genus of the Hominidae family, includes two species: Pongo pygmaeus o Bornean orangutan which lives only on the island of Borneo e I place abelii, Sumatran orangutan, which lives on the island of Sumatra.

The Bornean orangutans are found in the woods and forests within 1500 m of altitude (most of them are found within 500 m) scattered irregularly throughout the island even if it seems absent in the south-eastern areas. Large rivers represent insurmountable barriers for orangutans as they cannot swim.

Sumatran orangutans are found in the northernmost part of the island, in the primary forests of the tropical lowland, including mangrove forests and can be found up to 1500 m of altitude.


Orangutans are tree-dwelling animals and are considered to be the largest tree mammals on earth. The undergrowth of the forests where they live are extremely intricate and it would be difficult to move on the ground but this is not a problem for the orangutans as it lives, feeds and sleeps on trees (particularly valid for the Sumatran orangutan while the orangutan of the Borneo occasionally goes ashore). In this lifestyle they are helped by the arms and legs, both with prehensile hands / feet that allow you to support yourself and move from one tree to another without any difficulty.

They are not particularly social animals and do not live in large groups. Generally, the females live alone with the young, at most with another female and more rarely with an adult male. Generally, males and females only meet to mate. Each group of females has its own territory of 2-6 sq km which, however, often overlaps with that of other females and males, while the territory of a male never overlaps with that of another male.

They are diurnal animals therefore at night they sleep on beds that are prepared every night on the tops of the trees.

It has been seen that orangutans are extremely intelligent animals that are able to learn and interpret the behavior of other animals. For example, it has been seen that they often follow fruit-eating birds to discover new fruit trees, just as it has been seen that during the rain they can tear off a large leaf and put it on their heads to shelter from the water.

Orangutans are very sociable and curious animals. Check out this video where there are several orangutans playing in a shelter center.


The orangutan is an animal that has a certain sexual dimorphism as the male is larger than the females. Sumatran hair is much longer than the Bornean orangutan and typically features tufts of white hair on the face and groin.

Bornean orangutan

Sumatran orangutan (1)

They feature a receding forehead, prominent snout, and fleshy cheeks that can puff up to both impress females and scare off rivals.

The legs are not particularly long and not too sturdy, so much so that they cannot bear the weight of the body in an upright position for a long time and are equipped with feet with five toes shaped so as to be suitable for grip; the arms are very long and sturdy including the hands formed by five fingers which allow you to grasp objects very firmly.

A peculiarity is that females reach maturity around 7 years, a period in which they also stop growing while males continue to grow up to 10-15 years, a period in which they also reach sexual maturity.


Orangutans have several ways of communicating with each other: by voice, posture and touch. Males make long guttural sounds to keep other males away from their territory.


Orangutans are herbivorous animals but above all frugivorous, feeding mainly on fruit (it represents 60% of their diet) but they can also eat leaves, flowers and tree bark. Their favorite fruits are the fruits of the Durio tree (Bombacaceae family) even if the fig represents the fundamental element of their diet because it ripens at different times of the year and therefore is more available.

The orangutan has an excellent memory and remembers the location of the trees where it can find fruit and also the times of the year when it ripens.

Often the same tree rich in fruit must be shared with other orangutans but also with other animals such as gibbons or birds and this represents one of the few moments of sociality that is allowed. More than 500 species of plants have been recorded, of which the orangutan is nourishes.Sometimes they also eat small insects, larvae and bird eggs.


Orangutans are polygamous animals and can mate at any time of the year.

The gestation lasts about 8 - 8.5 months at the end of which the female gives birth to a single baby weighing about half a kilo. For the first 4-6 months the baby never goes away from the mother and when he is four months old, he starts taking solid food from the mother's mouth. It is weaned around 3 - 3.5 years and tends to stay with its mother until the age of 8.

Up to the age of one year the baby remains attached to the mother's chest by clinging to the fur, after this period it attaches to the back and can continue to do so even up to 2.5 years of age.

The females remain by their mother's side even after she has given birth to a new baby to learn from her how to raise children.

The female orangutans are extremely caring mothers and are the only ones who take care of the young as the males do not care.


The orangutan doesn't have many predators. Mainly its biggest predator is the man followed by the large snakes and the birds of prey that can snatch the younger ones.


The Bornean orangutan (Pongo pygmaeus) is classified in the IUNC Red list among animals at very high risk of extinction ENDANGERED (EN) having observed a decline in its population of 50% in the last 60 years. 2003 estimates indicate the population of Borneo at 45,000-68,000 specimens spread over 86,000 sq km but to date this figure is estimated to have significantly decreased.

The Sumatran orangutan (Pongo abelii) the IUNC Red list classifies it as CRITICALLY ENDANGERED (CR) that is to say critically endangered, therefore in an even more serious situation than the Bornean orangutan having observed a decline of more than 80% in the last 75 years. Estimates of 2004 indicate the population of this species equal to 7,300 specimens on a territory of about 9,000 sq km.

It has been estimated that if quick and decisive action is not taken, this decline will continue at the same rate for both species given the fact that their natural habitat is being destroyed due to the conversion of the forest into urban centers and agricultural areas. Other causes are: fires; wild deforestation, due to the increasing demand for timber; poaching, as orangutans are hunted both to be sold to zoos, for their meat and for some parts of their body used for traditional medicine.

Both species are listed in Annex I of CITES (Convention on International Trade in Endangered Species of Fauna and Flora, known simply as the "Washington Convention") which includes endangered species and therefore trade in specimens of such species. species is allowed only in exceptional cases.

It is established that, despite the islands where it lives there are several protected areas where the orangutan can live peacefully, most of its population lives in unprotected areas against which it is hoped that measures will be taken to try to curb the slow decline of this species.


The orangutan, in consideration of the fact that it is frugivorous and that it moves a lot, contributes significantly to the dispersion of seeds, especially the larger ones that cannot be dispersed by small animals.


(1) Image not subject to copyright as it is licensed under Creative Commons.

Video: Spitting Orangutan - Photo Researchers