Q&A

Q&A

What does “Orangutan” mean?
Orangutan means “People of the Forest”. In Indonesian or Malay, “Orang” means “People/Person” and “Utan (coming from the word Hutan)” means “Forest”. So, for example, if you want to say “Japanese”, you will say “Orang Jepun”. However, this name was given by foreigners and there is a theory that this is not how orangutans were originally called by the local. Some of the local names for orangutans include: Kogiu, Kahui, Kisau and Maias depending upon different tribes. But now, the name “orangutan” is most commonly used even among locals.
What is the life expectancy?
To be honest, we still have no conclusion on how long they would live up to. Recently, it has been reported by a study that Sumatran Orangutan’s life expectancy could be at minimum 58 years for males and 53 years for females (At age 53, orangutan was seen carrying around a baby so they might live even longer) (Wich et. al., 2004). Under the care of human hands, the world record for the oldest orangutan was a Bornean Orangutan, Gypsy (Female, Tama Zoo Park) which lived up until around 62 years old (Passed away in 2017). For Sumatran Orangutan, Puan (from Perth Zoo) lived up until around 62 years old (Passed away in 2018) according to Guinness World Records. For male orangutan, the oldest one was Bornean Orangutan, Jojo (from Singapore Zoo) which lived up until around 61 years old (Passed away in 2018).
Is Orangutan a smart animal?
Like the chimpanzees, orangutans have high levels of intelligence after humans. Orangutans can basically do anything that chimpanzees can do, like using hand as well as sign languages, and being able to recognise own self in front of the mirror (mirror-image recognition). They do not use equipment often in the wild but when they are under a human care or at the rehabilitation centre, they frequently use them. It is commonly thought that since chimpanzees are genetically closer to humans, they are smarter than orangutans. However, for example gorillas, which are also genetically closer to humans has the tendency of not being able to recognise mirror-images well, having worse result than the orangutan. Recently, they are many studies on comparing 4 great ape species by carrying out the same experiment on each of them: Chimpanzee, Bonobo, Orangutan and Gorilla. We are excited to find out more regarding orangutan’s intelligence!
What is their natural enemy?
The strongest and the worst predator is no other than us, humans. Currently, orangutans are under the threat of extinction by various activities carried out by us. However, this kind of relationship between orangutans and humans is not new. Until at least 10,000 years ago, orangutans used to live across Asia: Thailand, Peninsular Malaysia, Viet Nam, and Southern China. One theory state that one of the major reasons why orangutans are not living across these vast areas anymore is due to the massive hunt done by humans. In several sites of ruin, together with bones of polyps, many orangutan teeth were discovered from the soil (Dobois, 1992; Hooijer, 1948) too. Hence, for the people living in the past, orangutans were also one of the major targets of their hunts. Other than humans, clouded leopards and Sumatran tigers were also thought to be predators of orangutans. At the rehabilitation centres, there are also cases where python eat baby orangutans. However, leaving babies aside, it would be very difficult for non-human animals to prey on such a large, powerful orangutans that are mainly living up on the tree.
What kind of disease / sickness do they contract?
We think that orangutans get contracted for basically any disease or sickness we humans get. It is also reported that even in the wild, they have suffered from cases such as tuberculosis, hepatitis, Japanese encephalitis, dengue fever, malaria, and mumps (Wolfe et. al. 2002, Kilbourn et. al. 2005). Under the human care, there are also cases of kidney failure, pneumonia, cancer, and diabetes. At Sepilok Orangutan Rehabilitation Centre, there were many orangutans getting contracted with pneumonia, bronchitis, and parasites. Some died because of the parasite (Kuze et al. 2008).
Is it true that the grip strength of orangutans is 300kg?
Apparently it is stated on Guinness World Record that orangutan’s grip strength is 294kg but there is no evidence to back that up. It might be true that they have that sort of strengths as they live mainly on top of the tree and are able to hang just with one finger despite adult male weighing more than 80kg. However, to our understandings there is no scientific data and evidence to prove that their grip strengths are 200kg or even 300kg.
What is a “Long Call”?
This is the voice only from the male with flanges. It starts with a bubble-forming sound and ends with a roar which could be heard even from 800m away. It is common to last for about 1 – 2 minutes but there are also those which lasts only for short ten seconds. It is said to be a way of attracting females as well as to announce one's presence and keeping other males in check (Mitani 1985).
Listen to the voice
Are orangutans polygamous (having more than one wife)?
The ancestors of orangutans may have formed polygamous groups like gorillas (since sexual dimorphism is large; males are much larger than females). However, it is now considered practically promiscuous (both males and females mating with different orangutans). Female orangutans goes through estruses only once 6 – 9 years. During this period, they become fertile once every month from 2 – 3 days and unlike the usual day routine in which they avoid males, they proactively go seek for males. Males on the other hand, are constantly trying to go near females, and sometimes forcefully put them down for sexual intercourse (there are researchers who call this ‘rape’). Unlike the chimpanzee which has ‘sexual skin’, orangutans do not have it so sexual intercourse can still take place without females needing to be fertile. Especially in Borneo, unflanged males frequently force sexual intercourses (Mitani, 1985) but it does not cause serious injuries to the female. Fertile females will have sexual intercourse with various males, and even flanged males cannot fully prevent females from having sexual intercourses by/with other males. Also, from the long research of DNA analysis which investigated father-child relation in Sumatra, it was found that the child’s father varies greatly. There are also no results and observations obtained to prove one male dominates over many females or females only mate with a particular male (Utami et. al. 2002).
Do orangutans have territories?
No, they do not. Multiple orangutans can be in a same area/ region at a same time. At Danum Valley, we have observed two adult males, two adult females and two children on a tree (total of 6 orangutans) feeding and there was barely any quarrel or fight. In the case of male with flange: Flanged males are naturally hostile to each other, so they try to avoid each other. But in rare cases, when two flanged males come across each other (eg. near a female going through estrus), violent fight erupts. There are reported cases which one died during the fight, and it is also common to find injured flanged male, therefore we could say that there is a strong hostile relationship between flanged males. However, flanged males treat unflanged males warmly and sometimes feed on a same tree together.
How far do they move in a day?
The daily average distance is around 500m, but it is not rare to find orangutans moving only around 100m. There are also at times in which they move more than 2km a day. It is also observed that there is a tendency for flanged orangutans to move relatively little and young orangutans to move relatively long distances, but the distance ultimately depends on the day-to-day situation.
Are orangutans the closest animal to us humans?
Closest animal to us humans are not orangutans but chimpanzees. The common ancestors of human and chimpanzee separated only 6 million years ago but with orangutans it is 15 million years ago. Hence, chimpanzees are closer to us humans than to of orangutans. For an easier understanding, chimpanzees and humans are siblings raised in Africa whereas for orangutans, they are cousins born in far Asia.
I’ve heard orangutans are facing danger of extinction, so how many wild orangutans are there now?
It is predicted that in Sumatra Island, there are more than 13,000 Sumatran orangutans, less than 800 Tapanuli orangutans and in Borneo Island, there are around 57,000 orangutans (Wich et. al.,2016;Orangutan Population and Habitat Viability Assessment 2016, 2019). But just note, in the prehistoric times there were said to be 380,000 on Sumatra, 420,000 on Borneo, 340,000 on Peninsular Malaysia and at least 100,000 on Java Island (Rijiksen & Meijaard, 1999). It has also been said that the orangutans have gone extinct from Java Islands in the 17th century (Dobson, 1953).