ORANGUTAN: CHARACTERISTICS, HABITAT, FEEDING AND BEHAVIOR - BIOLOGY - 2025

The orangutan is a placental mammal, whose species make up the genus Pongo. This primate has a robust body, with the forelimbs longer than the hindquarters. In addition, each leg has five toes, of which four are long and the fifth is short and is opposite the rest.

This finger is similar to the thumb of humans and also performs a similar function. Thus, he can grasp and manipulate small objects. However, the way the joints and tendons are arranged are adaptations for an arboreal life.

Orangutan Source: pixabay.com

Currently, members of the genus Pongo live in Indonesia and Malaysia, on the islands of Sumatra and Borneo. Although in both regions they live in tropical rainforests, in Sumatra they are usually located up to a height of 1500 meters, while in Borneo they are not more than 1000 meters above sea level.

Two species were initially identified: Pongo abelii, which lives in Sumatra, and Pongo pygmaeus, distributed in Borneo. In 1917, researchers unveiled a third species, Pongo tapanuliensis that lives toward the northern area of ​​Sumatra.

All three species are critically threatened with extinction for different reasons such as hunting or the destruction of their habitat.

characteristics

Size

The orangutan has a large, robust body, lacking a tail. Among species a significant sexual dimorphism is shown. Thus, the female can be 115 centimeters tall and weigh approximately 30 to 50 kilograms. The male reaches 125 and 150 centimeters and its weight is 50 to 90 kilograms.

Fur

I put pygmaeus. Ltshears Young are born with pink skin, but as they grow the pigment changes to dark brown, almost black. The coat is rough and sparse, being unevenly distributed on the body.

Some adults, both male and female, may have partially bare or hairless backs. Hair color can vary, ranging from dark brown to pale reddish orange. However, it is usually reddish orange in color.

Between the two species there is a phenotypic difference that distinguishes them. Thus, the Sumatran orangutan has long hair and a pale red hue, while that of Borneo is orange, brown or reddish.

Extremities

The hind limbs are shorter than the forelimbs. When they are stretched from side to side, they can measure up to 213 centimeters. Their strong musculature allows the orangutan to balance among the trees and, together with its shoulders, support the weight of the body.

This primate has no restrictions on the movement of its hind limbs. This is because your hip joint has the same flexibility as your shoulder. In this way, it has a complete rotation that allows it to mobilize the limb at almost any angle.

Also, the ankle and knee joints are flexible, which makes it easier for this placental mammal to turn, jump, grab, and keep the body balanced when moving between the branches.

Cheek pads

The adult male has large cheek flaps, which are located between the eyes and the ears. These structures, called bridles, rest on the muscles of the face and are formed by subcutaneous tissue of a fibrous and fatty type.

Specialists point out that these pads may help to expand the range of vocalizations that the orangutan emits. This is because they channel sounds directly, just like a megaphone does.

Likewise, the bridles create a visual impact, making the animal look strong and intimidating to its adversaries.

Throat sacks

Both the female and the male have a sac that hangs from the throat. As the male matures, this structure grows larger. When said pendular laryngeal sac inflates, the primate's voice tone increases, thus producing long calls, which can be heard up to 80 meters.

Head

Zyance The cerebellum of the orangutan is larger than that of the human being. This area of ​​the brain is related, among other things, to postulate and body movements. In line with this, specialists suggest that its large size is related to the demands of an arboreal lifestyle.

This animal has a large head, supported by a thick neck. Although much of the face is hairless, the male may develop hair in some areas.

As for the mouth, it is prominent and is formed by two powerful jaws. Thanks to its strength, it can tear, crush and chew fibrous foods, such as fruits that are covered with thorns, nuts and tree bark.

Members of the genus Pongo use their lips to identify the textures of their food, before eating it. In addition, they move them and adopt positions that are part of the facial expressions with which they communicate.

A relevant aspect of the orangutan is that its teeth have 32 teeth, the same number that humans have.

Legs

Each leg has four long fingers and an opposable thumb that is smaller than the rest. This feature is similar to the human hand. However, the arrangement of tendons and joints are adapted for arboreal locomotion.

When the fingers are at rest they assume a curved position, thus creating a hook-like grip. In this way, the orangutan can hold and release the branches with either of its legs.

In addition, in the same way you can manipulate food, even putting a paw in your mouth while hanging from a branch

Also, without using the thumb, the orangutan can grasp small objects. For this, the primate supports the upper part of the fingers against the inner area of ​​the palm, creating a locked double grip.

Like all primates, members of the genus Pongo possess fingerprints, which could be used for identification. Another peculiarity is that each finger has nails, instead of claws.

Locomotion

Orangutans travel through the forest canopy, for which they can use only their forelimbs. This movement is known as brachiation. To climb, they do it with both front legs and with the two rear ones, in this way they hold on to the branches while they move horizontally.

Although it is an arboreal animal, it usually goes down to the ground when they need to travel long distances, because they may not get the branches of the right size to support their body. Also, they can do it when they need to find their food or water.

When moving on the ground, they generally walk quadruped, using their fists, unlike other great apes that use their knuckles. Occasionally, she may move bipedally.

Species

Orangutan in Borneo. Neil WWW.NEILSRTW.BLOGSPOT.COM Genome comparisons indicate that Pongo tapanuliensis separated from Pongo abelii approximately 3.4 million years ago. The divergence with Pongo pygmaeus occurred some time later, approximately 670,000 years ago.

There are marked differences between the habitats of the orangutan, which produced geographic and reproductive isolation. This has created that the primates in each region present some characteristics of their own.

Thus, the male orangutan living in Borneo has large cheek pads, a square face and a large throat pouch. Their body build is strong and they have shiny fur.

As for the Sumatran orangutan, it has long, light hair. Small bridles take the shape of a semicircle and both sexes may develop beards as they age. In relation to the face, it is triangular and the laryngeal sac is short.

Communication

Orangutans make a wide variety of sounds to communicate. The male makes long calls to attract females and to ward off other males trying to get closer to their sexual partner. Both the female and the male try to intimidate their conspecifics with low-pitched throaty noises.

Vocalizations are generally accompanied by body language and facial expressions. Thus, when the primate is upset, it purses its lips and sucks air through them, making a sound similar to a kiss, which is why this sound is known as a squeaky kiss.

Other sounds may be soft squeaks and moans, which hatchlings make when they feel scared.

Tools use

Orangutans, regardless of age and sex, have the ability to make and use various tools. According to research, this behavior is more common in Sumatran than Bornean orangutans.

In nature, this primate uses the objects it finds as tools. Thus, you can take a branch with leaves to scare away insects and large leaves like umbrellas, to shelter from the rain. Also, you could take a group of leaves to grab the fruits that have thorns.

In addition, they manufacture various utensils for daily use, to solve the situations that arise. In this way, they modify branches to open some fruits and to collect termites and ants.

The Bornean orangutan (P. pygmaeus) often uses some tools in acoustic communication. This can amplify the sound of the squeaky kiss it emits by using a few large leaves. Thus, it deceives the animals, by making them believe that they are bigger and fiercer.

Taxonomy

Animal Kingdom.

Subkingdom Bilateria.

Chordate Phylum.

Vertebrate Subfilum.

Tetrapoda superclass.

Mammal class.

Subclass Theria.

Infraclass Eutheria.

Order Primates.

Suborder Haplorrhini.

Infraorder Simiiformes.

Hominoidea superfamily.

Hominidae family.

Subfamily Ponginae.

Genus Pongo.

Species:

Habitat and distribution

David Dellier The species of the genus Pongo are geographically separated, inhabiting only the islands of Sumatra, in Indonesia and Borneo. This island is in the Malay archipelago in Southeast Asia, sharing territory with Sarawak and Sabah (Malaysia), with the Kalimantan region (Indonesia) and with Brunei.

In Borneo, the orangutan inhabits eight regions: Central Borneo, Kutai, Tanjung Puting, Gunung Palung, Kendawangan, Sabah, Gunung Nyuit, and in the Bukit Baka-Bukit Raya National Park region.

The distribution of the Bornean orangutan is patchy. They are rare or absent in the southeast, in the forests between the Rejang River (Sarawak) and the Padas River (Sabah).

This species prefers lowland forests, at less than 1000 meters above sea level, however, they can be located at 1500 meters above sea level, as occurs in the Kinabalu National Park. The great rivers constitute impassable natural barriers, so their dispersion is limited.

As for Sumatra, about 83% of the orangutans are in Aceh province, in the north of the island. Most of the populations are to the east and south of Leuser, spanning the entire border with Aceh.

Species

Although two species inhabit Sumatra, each one develops in specific regions. For example, Pongo tapanuliensis is located in the Batang Toru highlands, in an area of ​​1,500 km² divided into three forested regions.

Previously, this species was found in the Lumut swamp forests, but this territory is being used in oil palm plantations. This caused that P. tapanuliensis no longer inhabits these lowlands.

Pongo abelii also lives in Sumatra, but on this island, it is restricted in the northern area, limiting in the southern area with the Asahan River and in the north with Leuser, in the province of Aceh.

Habitat

Members of the genus Pongo live in diverse habitats, from mountain forests, 1,500 above sea level, to peatland forests. In these they can be found, both in the canopy and on the ground.

Within the ecosystems where these primates develop are primary and secondary forests, preferring peat and dipterocarp forests.

Also, it is found in lowland and grassland areas. While humans have been occupying the lower regions of their natural habitat, orangutans are moving towards the slopes of the mountains.

Other habitats include farmland, young secondary forests, with shallow lakes, and swamp forests. In these, the diversity of trees is greater than in mountainous areas, so they have high amounts of food.

Regarding the environmental characteristics, annually the precipitation is usually 4300 mm and the temperature ranges between 18 ° C and 37.5 ° C. As for the annual humidity, it is close to 100%.

In Borneo, the female's home range is between 3.5 and 6 km2, while in Sumatra it reaches 8.5 km2.

Danger of extinction

The IUCN has classified the Tapanuli orangutan (Pongo tapanuliensis), the Bornean orangutan (Pongo pygmaeus) and the Sumatran orangutan (Pongo abelii) within the group of species critically extinct.

Their populations have decreased in great proportions, for which this international organization maintains that if corrective measures are not taken to solve the threats that afflict them, they could soon disappear.

In the last 60 years, the Pongo pygmaeus decreased by 60%, with the projection that in a span of 75 years it could possibly decrease by 82%. The area of ​​distribution in Borneo is irregular, being extinct in many regions.

The highest concentration of this species is located in the forest around the Sabangau River, however, this area is also at risk.

As for the Sumatran orangutans, in 75 years their population decreased by 80%. In late 2012, specialists reported that the group to the north of the island was under threat from forest fires.

- Threats

Loss of habitat

The rainforest habitats where Borneo and Sumatran orangutans live are disappearing at an alarming rate. This is due to the deforestation of trees to obtain paper pulp, among other things.

Another factor that is having a negative impact is the conversion of large areas of forest into palm plantations. This oil from this plant is in high demand internationally due to its importance in the use of the culinary, cosmetic and biofuel (biodiesel) industries. But the appeal of this crop has serious consequences.

When forests are fragmented, local plant and animal communities are affected, annihilating them. In addition, the alteration of the environment contributes to global warming, due to the gases released in the burning of the land and the elimination of trees.

Orangutans that are forced to move can starve or be killed by people working on the plantations.

Other economic and service activities

A silver and gold mine is located in the Batang Toru Forest Complex, which has fragmented more than 3 km2 of the habitat of P. tapanuliensis.

Likewise, there is a proposal for a hydroelectric development that could affect around 100 km2 of the ecosystem of this species, which represents around 10% of the general population of the orangutan.

These productive activities could endanger the corridors that exist between the eastern and western ranges.

Fires

To clear the land of agricultural plantations, weeds are commonly burned. This activity can cause the immediate death of the primate or force them to move to other habitats, due to the loss of food.

Annually, large forest fires occur in Borneo. Thus, because of this, between 1983 and 1998, 90% of the Kutai National Park was degraded. Therefore, the population was reduced from 4,000 species that existed in the 70s, to only 600.

Illegal hunting

Orangutans could be killed for the commercialization of some of the parts of their organism. Thus, in Kalimantan many die every year due to the consumption of their meat. Also, their bones could be sold as souvenirs.

Sumatran orangutans are killed and the young are illegally traded as pets. Also, it often happens that they are killed by the farmers, when the orangutan attacks the fruit crops in search of food.

- Actions

Members of the genus Pongo are under the protection of Appendix I of CITES. On the other hand, there are many international organizations that are responsible for protecting the orangutan. Some of these are dedicated to rescuing the offspring that have been abandoned or that have been sold as pets.

These are rehabilitated and released back into their natural habitat. More than 150 primates have formed from this plan, through the Bukit Tigapuluh Sumatran Orangutan Reintroduction Project.

In Borneo, the main organization is the Borneo Orangutan Survival Foundation, which runs various projects, such as the Nyaru Menteng Rehabilitation Program

Other important conservation centers are Sebangau National Park and Tanjung Puting National Park (Central Kalimantan), Gunung Palung National Park (West Kalimantan) and Bukit Lawang, in Gunung Leuser National Park.

In Malaysia, protected areas include the Matang Wildlife Center and Semenggoh Wildlife Center (Sarawak) and the Sepilok Orang Utan Sanctuary (Sabah).

On the other hand, outside the countries of origin there are also orangutan conservation centers, such as the Frankfurt Zoological Society and the Australian Orangutan Project.

Reproduction

Female

In the female, menarche occurs when she is between 5.8 and 11 years old. Specialists indicate that it could occur earlier in those females that are larger and have more body fat than in those that are thin. The first offspring will be between 15 and 16 years of age.

There is a stage of adolescent infertility, which could last between 1 and 4 years. The menstrual cycle lasts between 22 and 32 days, with a menstruation of 3 to 4 days. As for menopause, in the female who is in captivity, it is approximately 48 years old.

Male

The male exhibits arrested development or bimaturism, which is influenced by the social context. This leads to adult males with flanges and subadults without flanges in the mature stage.

Sexual maturity in the male occurs between 8 and 15 years. However, secondary sexual characteristics in the flanged adult appear between 15 and 20 years of age.

Thus, once mature, it has large cheek pads on the sides of the face and a large laryngeal sac under the chin.

In subadults, aged 8 to 15 years, the testes have descended, making them capable of reproducing. However, morphologically they are very similar to an adult female. Specialists point out that the female seems to prefer to join those primates that display huge cheek pads.

As soon as the appropriate social conditions exist, especially if there is no resident male, they begin to develop cheek pads, long fur, throat pouch, and behaviors typical of an adult male.

This change usually occurs in a few months and brings with it a variation in mating strategies.

Mating and gestation

Males without cheek pads do not have a territory of their own, so they roam the area in search of a female in heat. When they find her, they force her to join him, generally achieving a successful copulation.

Bridled males act differently, vocalizing loud long calls, possibly to attract females in heat. This responds to vocalization, locating the male to mate.

Although there is no breeding season, the female shows a seasonal difference in ovarian function, related to the abundance or scarcity of food. Due to this, the chances of reproduction in times of ecological stress are significantly reduced.

Gestation lasts approximately nine months. Orangutans have the longest calving intervals of all primates. Thus, approximately eight years elapse between each birth.

The nest

Orangutans build their nests very carefully and systematically. As they do so, the young people in the group watch carefully, to learn. In making the nest, the primate follows a sequence of steps.

First locate a tree and then join several branches, making a base. They then bend the smaller branches up and braid them, thus increasing the stability of the nest. Due to their skills, these primates could build species of pillows and blankets.

Breeding

The calf weighs less than 1.5 kilograms and may have some whitish spots around the eyes and mouth. From birth to about two years, the young is almost exclusively dependent on the mother. She takes him on their travels, feeds him, and they sleep together.

By the time he is two years old, he has developed the skills to balance and climb. Thanks to this, he can move around following a locomotive pattern known as a friend's trip. In this, the youngster moves through the canopy of trees holding the hand of another primate.

Feeding

The species that make up the genus Pongo are opportunistic gatherers. They consume a wide variety of plant species, but are mainly frugivores. Thus, fruits make up between 60 and 90% of their diet, preferring those that have a fatty or sugary pulp.

Their diet varies according to the season, however, to a greater or lesser extent the fruits are always present, due to their easy obtaining and digestion.

In times of abundance of fruits, the male consumes more calories and they spend more time feeding daily than the females. In the off-season, the orangutan eats whatever fruit is available, as well as leaves and tree bark.

Also, under these seasonal circumstances, the primate can consume flowers, buds, sap, roots, honey, fungi, eggs, caterpillars, termites, spiders, among others. They could occasionally hunt small mammals, such as rats.

The water is obtained from various sources, including from those places where it is deposited during the rainy season, such as holes in trees and leaves.

Sometimes water can be difficult to reach, so the orangutan chews leaves to make a fleshy sponge, in order to use it to absorb water.

Food preferences

The Sumatran orangutan prefers the fig (Ficus carica), over any other fruit. On the other hand, those who inhabit the island of Borneo consume around 317 different foods, including sprouts, young leaves, insects, bird eggs and honey.

Within the island of Borneo, orangutans tend to live in the lowland dipterocarp forests. Occasionally, they may eat slow lorises, a small primate with a very calm temperament.

Geophagy

Geophagy is a feeding behavior that is characterized by the fact that the animal consumes earth or an earthy substance, such as clay. The orangutan does so occasionally, associated with three organic situations.

Thus, according to specialists, this primate eats small rocks or earth to add mineral elements to its diet. You could also consume clay so that it absorbs any toxic substances you have ingested. Likewise, they usually eat dirt to alleviate a digestive disorder, such as diarrhea.

Behavior

On a daily basis, orangutans spend more than 95% of their time resting, feeding and moving between resting and feeding sites. This pattern features two high peaks, one in the morning and one at night.

When they leave the night nest, the orangutan spends two to three hours foraging vigorously in the morning. Then, during the noon hours, it rests and in the afternoon it travels to its night nest. At dusk, she begins to prepare the place where she will rest for long hours.

Social

This group of primates establishes social relationships with the members of their group. However, the flanged adult male is the loneliest of the subadult orangutans. He generally travels alone and almost exclusively joins temporarily with a female, with the intention of reproducing.

The adult female is grouped with her young, with young people, who are not always her children, and with other females. Generally, the relationship between mother and baby lasts for several years, while the time that the couple is together is relatively very short.

In this semi-solitary social system there is competition between males for a female in heat. As part of the fight, the male uses his long call, with the intention of intimidating the other males, at the same time that he attracts females suitable to reproduce.

Probably the encounter between two males causes a fight, which could last a few minutes or up to an hour. At the end, both opponents could present serious bodily injuries.

Dispersion

Research on the social structure of these primates indicates that it is associated with the distribution of food, especially fruits. Because of this, they are forced to disperse throughout the year.

During group separation, the female tends to settle in territories that could overlap with other females. However, it generally does not link to them.

As for the male, they usually disperse far from the mother's home and temporarily enter a transitory phase. This stage ends when he manages to displace a dominant male from his territory. It should be noted that adults always dominate sub-adults.

Since the orangutan has a high social tolerance, it adapts easily to aggregations around fruit trees. However, as the male matures, they may become more territorial and are often housed separately.

The feeding groups are formed by adult and subadult females and males, where the animals arrive and leave the site independently. As there are a large number of fruits, competition for them decreases, so that primates can socialize with each other.

References

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