ORANGUTAN BEHAVIOR: COMMUNICATION, CULTURE, SEX, MURDER

ORANGUTAN BEHAVIOR

Orangutans are arboreal (live mainly in trees), scansorial (able to or good at climbing), diurnal (active during the daytime), motile (move around as opposed to being stationary), solitary and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). Flanged males (males with large cheek pouches are at the top of the social hierarchy. f. They can outcompete unflanged males for a mate and will typically choose an older female rather than an adolescent one. [Source: Alexander Hey, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: orangutans are semi-solitary for most of their adult life. They are motile, and their day-to-day movements are largely a response to spatiotemporal variability in food availability. They eat mainly ripe fruits and food distribution is variable, so most orangutans travel alone unless it is a female with her offspring. Adult flanged males are the most intolerant of other members of their species unless they are actively trying to form a consortship with another female, thus they are rarely territorial (defend an area within the home range). Besides when mating, orangutans are tolerant of other members of their species in their home range, however males tend to stay away from each other more than females. They are motile, and their day-to-day movements are largely a response to spatiotemporal variability in food availability. /=\

Tool use also defines orangutans. Most studies have focused on the behavioral differences between the two regional populations of orangutans, or Bornean and Sumatran Island populations. Most orangutan offspring learn all of their behaviors from their mother, including tool use. Interestingly, research has found that different populations of orangutan display different behaviors based off of their geographic region, an indication of a culture. Roof building of nests (to stop rain) was observed in Borneo, but not on Sumatra. There were other behaviors, like covering yourself in leaves to protect from the sun, that were observed in some of the populations on Borneo and Sumatra, but not all. /=\

Websites and Resources: Animal Diversity Web animaldiversity.org ; BBC Earth bbcearth.com; A-Z-Animals.com a-z-animals.com; Live Science Animals livescience.com; Animal Info animalinfo.org ; World Wildlife Fund (WWF) worldwildlife.org the world’s largest independent conservation body; National Geographic National Geographic ; Endangered Animals (IUCN Red List of Threatened Species) iucnredlist.org

Orangutan Tree-Dwelling Behavior

Orangutans are mostly active in the day and live mostly in primary rain forests, ranging from those found in swamps to those in mountains as high as 1,500 meters. They need a fair amount space. Males generally need two to six square kilometers each.

Orangutans are generally placid creatures. They sleep in the canopy in large platform nests made from leaves and branches. They usually build a new nest every evening but will sometimes sleep in the same one for more than one night. Some can make a new nest in less than 5 minutes. When it rains orangutans sometimes climb underneath the nest, using it as an umbrella.

Orangutans spend most of their lives eating and resting. They move slowly during the day, covering only 200 to 1,000 meters a day, considerably less than gibbons. They are most active in the morning and the afternoons. Orangutans’ large size makes it much more difficult for them to move through the forest than lighter, more agile monkeys and gibbons. They can not swing through the canopy, where the branches too light and thin to bear their weight, like gibbons. Thus orangutans move around in lower sections of the forest by moving to the end of branches until their weight drops them to where they can grasp onto another branch.

Orangutans generally dislike water. Some orangutans spend as much as half the day on the ground. When they do drop down to the rain forest floor to forage they travel around on all fours foraging at intervals up to six hours. Males have been observed walking through rice fields and napping on the ground and even building nests on the ground. .

Orangutan Anti-Social Behavior

"Large and mostly silent, orangutans are relatively slow, solitary animals. They do not travel in big, noisy groups like chimpanzees, or in large families like gorillas. Spotting one orangutan did not mean the others were nearby. Traveling 100 feet in the dense tropical rain forest canopy, orangutans are masters of hide and seek — now you see them know you don't." [Source: “Reflections of Eden” by Biruté Galdikas]

Orangutans are the least social of the great apes. They are largely solitary and don't seem to care much for the company of their own sex or members of the opposite sex. Adult males and females only come together when they have to mate. Males are nearly always seen alone and go out of their way to avoid each other. Their only contact it seems is vigorously defending their territories against other males. The Dyak believe that human loners belong to the tribe of the orangutans and gregarious people are kin to of gibbons.

Orangutans rarely groom each other like many other primates do. Male-to-male combat, females sneaking way from males they didn't want to mate with are characteristic behavior when they do come in contact with one another. The only real bonding is between a mother and her offspring. Occasionally females with assorted offspring are seen traveling and foraging together but this is rare. Sub adult orangutans are more likely to be seen the company of other orangutans than older ones. They travel alone or with their mothers and sometimes play with other sub adults of both sexes.

Orangutans are the only diurnal primates that exhibit such anti-social behavior. Galdikas believes the solitary nature of orangutans makes sense in their rain forest habitat. If a group of orangutans invaded a fruiting tree they would strip the tree of every ripe piece of fruit and none of the apes would be satisfied. Alone they get enough to satiated their huge appetites.

Orangutan Dreams, Aggression

Apes may dream; they have rapid eye movement. One naturalist described a young orangutan who woke up screaming as if they had just had a nightmare. The orangutan t turns out had witnessed his mother being shot down from a tree by tribesman and killed, skinned and eaten before his eyes. Orangutans are also quick learners but sometimes at the cost of unanticipated cost. An orangutan couple in Russia followed instructions from a video on good patenting and then became addicted to television and neglected each other.

Bill Brubaker wrote in Smithsonian magazine, Males are frighteningly unpredictable. Galdikas recalls one who picked up her front porch bench and hurled it like a missile. "It's not that they're malicious," Galdikas assures me, gesturing toward the old bench. "It's just that their testosterone surge will explode and they can be very dangerous, inadvertently." She adds, perhaps as a warning that I shouldn't get too chummy with Tom and Kusasi, "if that bench had hit somebody on the head, that person would have been maimed for life." [Source: Bill Brubaker, Smithsonian magazine, December 2010]

When I visited Gunung Leuser National Park in Sumatra my guide told me several stories about aggressive orangutans. The guide said once a large male started chasing him down a trail and rolled itself into a ball and somersaulted down a downhill section of trail to catch up to the guide, who said he was vigorously man-handled by the ape but emerged more or less uninjured.

Orangutans Customs and Culture

Orangutans pass on behavior from one generation to the next. Some of these “customs” are unique to particular groups which some scientist argue is an expression of “culture,” which is defined as the ability to invent new behaviors adopted by a group which are then passed down to succeeding generations. It was previously thought that only humans and chimpanzees possessed “culture.”

There are a number of examples of orangutans living in one area that possess culture and customs that other groups don’t have. One group at Gunung Palung National Park in Borneo, for example, threatens strangers by making kiss-squeaking noise into a handful of leaves. In Sumatra, orangutans use sticks to pry nutritious seeds from prickly, difficult-to-eat “Neesia” fruits. Others make a raspberry-like noise before turning in for the night, use their fists to amplify sound, employ leaves as gloves when handling spiny fruits, dip leaves in a hole with water and lick the leaves, use leaves as napkins and employ sticks to poke out sections of termite nests.

What is remarkable about the finding compared to other apes is that orangutans are much less social than chimpanzees and humans. Galdikas wrote in Science, “If orangutans have culture, then its tells us that the capacity to develop culture is very ancient...orangutans separated from our ancestors and from the African apes many millions of years ago.” The study suggests “they may have had culture before they separated.”

Orangutan Communication

Orangutans communicate with vision, sound and mimicry and sense using vision, touch, sound and chemicals usually detected with smell. Orangutans are generally quieter than other higher primates. Scientist have recorded 15 orangutan vocalizations, the most notable of which is the “long call,” is a hair-raising, minutes-long, sequence of roars and groans by the male that can carry a mile and are used to define his territory and space himself from other orangutans. Male mating calls are rarely heard.

Alexander Hey wrote in Animal Diversity Web: Communication among orangutans is perhaps one of the most complex and diverse characteristics of these animals. The most distinct and charismatic form of communication for orangutans are the "long call," performed by adult flanged males only. Heard from over a mile away, these long calls invite behavioral responses from all ages and sexes, but other adult males respond the most. The flanged male uses their throat sac to emit a long, sometimes minutes long, series of "roars." Their cheek pads funnel the sound in a particular direction, and studies have shown males will sometimes make these calls in the direction they are traveling to warn other males they are on the move towards them as early as one day in advance. Other males use their long calls in response to trees falling, mostly because some males will knock down trees as a form of dominance. Some males use their long calls to attract females, and it has been noted that Bornean female orangutans can recognize the calls of individual males. [Source: Alexander Hey, Animal Diversity Web (ADW) /=]

Besides long calls, there are many other forms of orangutan vocal communication. Bornean orangutans were observed in 2019 to have 11 vocal signal types. These vocal signals can be anything from displeasure, to playful infants fighting, to warning of rainfall. In fact, Sumatran orangutans were observed suppressing alarm calls up to 20 minutes when waiting for threats to pass. This means they are capable time-space-displaced responses or giving information about an event that has happened in the past. /=\

Bill Brubaker wrote in Smithsonian magazine, Galdikas “has made discoveries about how males communicate with one another. While it was known that they use their throat pouches to make bellowing "long calls," signaling their presence to females and asserting their dominance (real or imagined) to other males, she discerned a call reserved especially for fellow males; roughly translated, this "fast call" says: I know you're out there and I'm ready to fight you. [Source: Bill Brubaker, Smithsonian magazine, December 2010]

Orangutan Vocal Control and Kazoos

Adriano Reis e Lameira wrote: Evidence suggests that wild orangutans use vocal control in their natural environment to communicate and pass information between individuals and generations. For example, wild orangutans can modify their alarm calls with hands and leaves to make them sound bigger, depending on how dangerous the predator they encounter is. ild orangutan mothers delay alarm calls in response to predators until there is no danger, before then informing their infants of the danger that just passed through the forest floor below. Such an ability not only indicates some degree of vocal control, but also another key prerequisite for speech — the ability to communicate about the past. [Source: Adriano Reis e Lameira, University of St Andrews, The Conversation, September, 2019]

“To find out more about these abilities, we gave captive orangutans at the US’s Indianapolis Zoo the opportunity play a membranophone — — a class of musical instrument that includes the kazoo. Kazoos and other membranophones are unique in that despite their resemblance to a flute or a whistle, merely blowing a constant stream of air into them produces no sound. To activate the instrument, the player must hum or talk into the kazoo. This is because it is the bursts of air produced by our vocal folds opening and closing when we vocalise that make the membrane of the instrument vibrate, and the instrument play.

“In our study, some of the orangutans activated the kazoo within minutes, producing sounds of varying pitches and durations in response to kazoo demonstrations by the human experimenters. The speed with which these orangutans changed the quality of their voices shows that they were producing the sounds at will, rather than through training — which, as any dog trainer will reassert, requires months of reflex building and conditioning. These findings show that orangutan voice control lags not far behind that of humans. They confirm that the vocal abilities of great apes have been largely underestimated. The fact that only some of the orangutans managed to play the kazoo shows us that the capacity and/or motivation to demonstrate vocal control differs between individuals.

Orangutan Gestures

Alexander Hey wrote in Animal Diversity Web: Gestures are perhaps the most widely-used orangutan form of communications. They have a range of meanings, from requesting objects, sharing tools, warning of harmful behavior, climb over/on me, resume play, etc. Gestures can be made by hands or feet, though hands are preferred. Orangutans have also been known to repeat gestures when their message was only partially understood, and in some cases can change their gestures if they believe their message was not understood at all. [Source: Alexander Hey, Animal Diversity Web (ADW) /=]

In 2019, scientists announced that they had deciphered some of the complex vocal signals and gestures that wild orangutans made and used to communicate rapidly to each other. Rob Waugh wrote in Yahoo News: “University of Exeter scientists identified 11 vocal signals and 21 physical gestures, such as pushing out a lower lip, shaking objects and ‘presenting’ body parts. The animals use these sounds and gestures to communicate ideas and requests such as “climb on me”, to each other — or to say “stop that”. The animals react quickly, responding with more gestures or sounds in less than a second in 90 percent of cases. [Source: Rob Waugh, Yahoo News, December 10, 2019]

“Sounds included the “kiss squeak” (a sharp kiss noise created while inhaling), the “grumph” (a low sound lasting one or two seconds made on the inhale), the “gorkum” (a kiss squeak followed by a series of multiple grumphs), and the “raspberry”. “We observed orangutans using sounds and gestures to achieve eight different ‘goals’ — things they wanted another orangutan to do,” said University of Exeter scientist Dr Helen Morrogh-Bernard, founder and co-director of the Bornean Nature Foundation (BNF). “Orangutans are the most solitary of all the apes, which is why most studies have been done on African apes, and not much is known about wild orangutan gestures. “We spent two years filming more than 600 hours of footage of orangutans in the Sabangau peat swamp forest in Borneo, Indonesia. “While some of our findings support what has been discovered by zoo-based studies, other aspects are new — and these highlight the importance of studying communication in its natural context.”

One of the new findings is that while orangutans favour hands over feet when making gestures, they use their feet more than chimpanzees for this purpose. Video footage of 16 orangutans (seven mother-child pairs and a pair of siblings) yielded a total of 1,299 communicative signals — 858 vocal signals and 441 gestures. Vocal communication increased when the other orangutan was out of sight.

Orangutans loudly smack their lips and throw branches when they sense an invader. When they see a friend they suck their lips in and get a goofy look on their face. Orangutans in both Borneo and Sumatra use leaves to make loud noises. Different groups also make “kiss-squeak” and sputtery raspberry noises. Once when an orangutan was accused of murdering an infant orangutan it raised its hands above its head and then drooped them down fluttering in front of him as if is to say "I give up you win." Bornean orangutans funnel their lips and scream when scared.

Localized Orangutan Slang

Joe Pinkstone wrote in The Telegraph: Roughly 70 orangutans living in six different social groups in Borneo and Sumatra were studied by researchers at the University of Warwick, and their vocalisations recorded. Some of the groups were very sociable, regularly interacting with one another in close proximity, while others were more laid back and spread out. In the high-density groups, scientists identified a large number of original calls, with individuals using novel sounds that are rapidly picked up, but just as quickly discarded, much like school children going through fads where certain phrases suddenly become popular before just as quickly becoming grossly uncool. [Source: Joe Pinkstone, The Telegraph, March 22, 2022]

But in the smaller, more relaxed groups of apes, the animals use more traditional calls and are less prone to experimenting with new sounds. However, if a new call is introduced, it is more likely to stick around and become part of the permanent primate vernacular. “Orangutans living in low densities have indeed a rich ‘slang’, that is, a collection of calls that they recurrently use and gradually build upon,” study author Dr Adriano Lameira, assistant professor of psychology at the University of Warwick, told The Telegraph. “Whereas vocal communication by orangutans in high densities is like a cacophony. In these populations, it seems that novelty is at a premium.”

The research, published in Nature Ecology and Evolution, is the first to show the vocabulary of apes is not fixed, but is fluid and subject to ongoing group dynamics. “Our study shows that an individual's social community moulds how that individual communicates, as is the case with any human learning a language,” Dr Lameira said. “What was unknown was that these vocabularies differ or vary according to the type of social community an orangutan lives in. This disproves the long-standing idea that great apes have automatic, hard-wired, reflexive and immutable calls all their lives.”

Orangutan Male Behavior

Males roam the forest alone, consuming huge amounts of fruit. Fully developed males are known as prime males. When they are at their peak they have full cheek pads, large throat pouches and make loud bellowing noises that carry over long distances to announce their presence. Prime males are only in top physical condition for a few years. Chasing after females and fighting other males takes its toll. Their cheek pads and throat pouches shrink and their ability to make loud calls diminishes. When this occurs their reproductive life cycle ends.

Males sometimes get into vicious fights during the mating season. These fights can be deadly. Males have been seen with severe wounds and canine marks all over their body from fights with other males. In some cases injuries are so bad they prevent the orangutans from moving through the forest and eating, leading to the animal’s likely death. In most cases when two males meet, the dominate one is clear and a fight is avoided when the subordinate one backs off. Females are less hostile to one another that males. Occasionally pairs of females hang out and travel together for up to three days.

Describing a fight between males, Galdikas wrote, “They grappled furiously, biting one another; they fell repeatedly and chased each other into the trees again to resume the fight. Their backs glistened with sweat, its pungent odor lingering on the ground long after they were back in the trees. A few times they pulled apart and stared intently at each other. Then after more than 20 minutes, they separated and sat on adjacent trees. With a mighty heave T.P. threw a snag — and roared. The other male disappeared.”

Cheryl Knott, an anthropologist at Borneo’s Gunung Paiung National Park, Indonesia, wrote in National Geographic: A “significant find at our site was that fully developed adult male orangutans, known as prime males, stay in top physical condition only for a few years. Prime male Jari Manls was in top condition in April 1997 when National Geographic first took his photo (the August 1998 issue). But 19 months later he was a shadow of his former self. Shriveled cheek pads illustrate the difficulty of maintaining peak condition. Martina was likely fathered by Jarí during his prime. Following females and fighting with other males wears them down, diminishing masculine traits such as full cheek pads and large throat pouches and curbing certain behaviors like mating and long-calling — a loud bellowing made to announce their presence. As these features disappear, males become what I call past prime, a condition that usually signals the end of their reproductive cycles. [Source: Cheryl Knott, National Geographic, October 2003]

“Many orangutan males delay developing prime traits for several years, although they’re still capable of fathering offspring. I believe the environment may be partly responsible, Natural plant cycles cause severe fluctuations in fruit production. During shortages orangutans consumer fewer calories — and in females this translates to lower fertility. In response males may wait to attain their prime condition until future time when food is more abundant and they have the best chance of reproducing.”

Orangutan Murder, Deceit and Lethal Female Aggression

As is true with chimpanzees it was discovered that orangutans are capable of murder. One seven year-old drowned and mutilated two infant orangutans in a river and was caught trying to do the same to a young female. What was surprising about the murderer was that it had spent more time around humans than any of the other orangutans at the Tanjung Puting rehabilitation center. There have also been reports of orangutan kidnaping. A female who was not lactating broke into a rehabilitation center in Sumatra and carried off an infant into the forest.

The New York Times reported: “Great apes, for example, make great fakers. Frans B. M. de Waal, a professor at the Yerkes National Primate Research Center and Emory University, said chimpanzees or orangutans in captivity sometimes tried to lure human strangers over to their enclosure by holding out a piece of straw while putting on their friendliest face. “People think, Oh, he likes me, and they approach,” Dr. de Waal said. “And before you know it, the ape has grabbed their ankle and is closing in for the bite. It’s a very dangerous situation.” Apes wouldn’t try this on their own kind. “They know each other too well to get away with it,” Dr. de Waal said. “Holding out a straw with a sweet face is such a cheap trick, only a naïve human would fall for it.” [Source: Natalie Angier, New York Times, December 22, 2008]

On the first recorded killing of orangutan by another female. Sam Wong wrote in New Scientist: “It was a deadly rumble in the jungle. A female orangutan was attacked and killed by another female and a male — the first time lethal aggression has been seen between females of the species. Female orangutans are normally solitary, and very rarely engage in fights. It’s also unusual for females and males to form coalitions. In this case, Kondor, a young female, and Ekko, her suitor, beat and bit an older female named Sidony in the swamp forests of Indonesia’s Mawas Reserve. Sidony sustained serious wounds that became infected, and she died two weeks later. “It was very surprising,” says Anna Marzec at the University of Zurich, Switzerland, who observed the behaviour. “We had never seen anything like this before.” Marzec described the event in the journal Behavioral Ecology and Sociobiology,[Source: Sam Wong, New Scientist, February 4, 2016]

“It’s unclear why Kondor showed such unusually aggressive behaviour. Female orangutans don’t defend their territory and the researchers saw no sign of any provocation. “We think the presence of the male had a lot to do with the fact that she was brave enough to attack and then was so persistent,” says Marzec. Kondor had recently lost an infant. Just before the attack, she was in a courtship with Ekko. The pair encountered Sidony and Ekko inspected her before returning to mate with Kondor. Kondor then broke away from Ekko to attack Sidony, and Ekko joined in. Another male, Guapo, came to Sidony’s defence, and chased Ekko away, but Sidony had already received severe injuries. The area is becoming more crowded for orangutans because of habitat destruction, and this could have played a role in the unusual behaviour. “We want to see if it’s going to happen more often now,” says Marzec.

Orangutan Reproduction

Orangutans one of slowest rates of reproduction of any animal. Females give birth on average once every nine years— thought to be longest span of any mammal—even though they ovulate and are capable of getting pregnant once a month. It takes an average of 15.4 years for a female to become reproductively active, with a range of 13-18 years. Orangutans breed so slowly because females devote a lot of attention to raising their young, which develop slowly, requiring years of maternal care and training. Females spend up to 10 years raising a single offspring, during which time they don't mate. Females sometimes only conceive during periods of high fruit production.

Orangutans are polyandrous, with females mating with several males during one mating season. According to Animal Diversity Web: Females that are reproductively active are usually traveling alone or with their offspring. If there is a male and a female traveling together, it may be due to a sexual relationship or a coincidental closeness in proximity from feeding. Males, flanged or unflanged, pursue females that are reproductively receptive, and will fight for a reproductively active female. Flanged males have cheek pads and longer vocalizations, as well as usually being more dominant and sexually successful. However, they are extremely intolerant of other males, using their vocalizations from throat pouches as a way to alert other males of their presence. [Source: Alexander Hey, Animal Diversity Web (ADW) /=]

Both males and females reach sexual maturity at around seven or eight years of age. However, females do not usually give birth until they are about 12 and males do not reach their full sexual maturity until they are around 14. Females prefer larger older males, who in turn are successful beating off male rivals. Galdikas observed one young female abandon a young male “friend” to have sex with an older male. The young male seemed jealous and depressed and slunk around in the trees nearby but did not challenge the older male. Sexual competition helps explain why males are so much larger than females. Males need to be strong to fight one another, females do not and if anything a large size makes it more difficult to maneuver around the trees.

Orangutan Sex

Once the female is receptive to reproduction, an involuntary consortship is formed for anywhere from a few days to a month. During this time, the male and female travel together, and both flanged and unflanged males exhibit mate guarding behavior to keep other males away. However, usually more dominant, flanged males are more successful in mate guarding, while unflanged males being kicked out by a larger male if encountered./=\

Females are not ready to mate often but when they are males come from all over.The females usually do the choosing and they can be quite bold, displaying their genitals, swinging around in a showy manner and even whacking an uninterested male on the head with a piece of fruit or a branch. When a female orangutan gets the urge she will tweak the penis of the nearest male which males seems to find more embarrassing than arousing..

Orangutans sometimes have sex in the face to face position. They are one of the few animal species other than humans that do this. There are even examples of platonic love in the orangutan world. One male liked to have sex with unwilling females but at his side almost all the time was another female he never had sex with. Sometimes clumsy or inexperienced males cause the females to scream in pain or irritation. Females are sometimes raped by large males.

On his encounter with a lusty male orangutan, John Gittelsohn of Bloomberg wrote: “The sign at Camp Leakey on the Indonesian island of Borneo says: “Never stand between a male and a female orangutan.” We were watching a group of female orangutans feasting on bananas, babies clinging to their bellies, when we learned why. First came the sound of snapping branches, like a bulldozer crashing through the forest. The mother orangutans stuffed their mouths with bananas and started to flee just as Tom, a massive red-haired ape with black cheek pads framing his glassy brown eyes, swung down from the trees. One female, Akmad, was too slow to escape the long arm of Tom. He grabbed her ankle, tossed her on her back and had his way in less than a minute. When Tom was finished, he let out a loud fart. [Source: John Gittelsohn, Bloomberg, June 3, 2012]

Orangutan Young and Patenting

Females usually give birth to one infant at a time The gestation period averages 245 days.The mean birth weight is about 1½ kilograms. Baby orangutans remain close to their mothers. They like to stare at their mother's face. The single infant remains with its mother for eight or nine years. Chimpanzees, gorillas and orangutan mothers dote on their young. Mothers raise their young in fairly settled surroundings, nursing them for six years, never leaving them, and not weaning them until they are pregnant with another baby. After they have been weaned young orangutans usually establish a territory near their mother’s territory. Only when they are seven or eight do they go off and establish a territory of their own.

"Young orangutans are utterly charming—wide-eyed, playful and trusting." They are often sought as pets. Young orangutans learn the skills necessary to survive in the forest from their mothers. Young protest loudly of their mother won’t share food with them. Those who lose their mothers are often unable to take care of themselves. When the mother deems it is time for young to move on she can be quite rough in persistent in throwing the young out of her nest.

Females develop a strong bond with their young. Young orangutans cling to their mothers for the first one year or so of their lives and often continue to ride on their mothers until they are 2½. Often mothers will hurl themselves through the canopy at great speed with their young holding on tight to handfuls of skin and hair. A one-year-old youngster adopted Galdikas as his mother. He cling to her night and day. So unyielding was his affection Galdikas couldn't take a bath without him whining to grab hold of her. Changing her clothes was next to impossible.

According to Animal Diversity Web: Newborn orangutans are extremely dependent upon their mother, and weigh 3.5-4.5 pounds. Body contact is continuous for the first three months, but entire dependence on food lasts for the first two years. At around three years of age, young orangutans make play nests and start exploring their habitat while always in view of the mother. Full weaning of milk does not occur until about 3.5 years old. Young orangutans will spend the next few years imitating their mother's behavior through trial and error. The mother will teach her young everything from swinging through trees, using tools for food, and overall how to live in the forest. [Source: Alexander Hey, Animal Diversity Web (ADW) /=]

At about six or seven years of age, offspring are considered adolescents and spend more and more time away from their mother. At this age, females express an interest in sexual selection and can be reproductively active, although males tend to pursue older, more established females. Females may not give birth until they are 10-15 years of age. Neither males or females are fully grown at this age, and will occasionally come into contact with their mother during this period. Their mother may have given birth to a sibling by then, giving these adolescents someone to play with. Males will not reproduce until they are 13-15 years old, despite being reproductively fertile well before that. /=\

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated December 2024