Orange You Glad I Said Orangutan? Quiz

Answer: Indonesia and Malaysia

It is more common to hear that they are only found on the islands of Borneo and Sumatra. While Sumatra is entirely part of Indonesia, Borneo is tri-national, and actually gets its name from the country of Brunei. However, the parts of the island where orangutans live are in the Malaysian states of Sarawak and Sabah, and the Indonesian states of East, West and South Kalimantan.

There is fossil evidence that orangutans once inhabited Vietnam, and they have been given the name Pongo hooijeri, although it is not actually clear whether they were in fact a distinct species.

Answer: No

There are, in fact, currently held to be three distinct species of orangutan, although classification is a slippery business, and this may change. Until 2017, they were classified into two species, Sumatran and Bornean. Then the Sumatran populations were identified as being sufficiently different to be considered two species. The image in the question showed the range of each species using identifying colors.

Originally, Linnaeus gave orangutans the name 'Simia satyrus' (satyr monkey), believing them to be a single species. When it was discovered that there are multiple species, they were reclassified into the genus Pongo (from a Bantu word used for any large primate that was originally used to describe chimpanzees), with the Bornean species names P. pygmaeus and the Sarawakan species P. abelii. When the isolated Sarawak orangutan population that lives in Tapanuli was decreed to be a species of its own, not a subspecies of P. abelii, it was named P. tapanuliensis. Current classification has three subspecies of the Bornean orangutan (but it is always possible that this could change): P. p. pygmaeus is found in the northwest part of the island, P. p. morio in the southeast, and P. p.wurmbii in the middle of the others.

Answer: In trees

Looking at an orangutan, the extraordinary length of their arms is immediately apparent - the armspan of an adult is about half again its height! Orangutans have several adaptations to their hands that help them move readily around in trees. One obvious one is that their fingers, in a resting position, form a curve so that they can be hooked over a branch without needing to utilise muscles to make the appropriate shape. A second is that their fingers are long enough to wrap around small branches and then fit under the palm, creating a tight grip that does not require the use of the opposable thumb. While all orangutans spend most of their time in the trees, it has been observed that Bornean orangutans spend more time on the ground than Sumatran ones. It has been suggested that this may be due to the absence of one of their main predators, the tiger, on Borneo. After over 3,000 hours of observation, Tapanuli orangutans had never been seen on the ground at all!

The orangutan in the photo is a Sumatran orangutan, P. abelii.

Answer: Opposable big toe

Like their fingers, the toes are very long and curved. The fact that their big toe can act in the same way as an opposable thumb means their feet are useful for gripping branches (and for peeling bananas while hanging from a tree branch).Orangutan joints, for both the upper and lower limbs, are extremely flexible, so they can rotate to allow a wide range of positions, more than a human's arm movement, and much more than a human's usual leg movement.

While not as long as its arms, the orangutan's legs are also quite long for its height.

Answer: Definitely male - look at those cheeks!

Orangutans are sexually dimorphic, meaning that there are significant differences between adult males and females. The one shown here is the development of large cheek pads, called flanges, in an adult male, which helps them produce louder calls to attract females and intimidate rival males. Although males are physically mature at around 15 years of age, they only start to develop flanges around that time. Development is slow if there are dominant males around, but can be very quick if they themselves become the local dominant male. Females have much smaller cheek pads, which are basically just muscle; males store fat in the flange to increase its size. The face of a male is also likely to have a more pronounced beard and/or moustache, but that does vary between the species. Overall, males are usually larger than females, nearly twice as heavy and half again as tall. However, this is not readily seen when you only have a single specimen to consider, and there is (of course) individual variation.

All orangutans have long fur, whose color ranges from bright orange to brown, and strong fingers for hanging around in trees.

Answer: Fruit

A frugivore eats fruit. Orangutans are primarily, but not exclusively, frugivores, and feast on durians, jackfruit, breadfruit, figs, and other tropical treats. When fruit is not available, or occasionally just for a change, they also eat insects, seeds and leaves, tree bark, honey and bird eggs - in fact, whatever they can find! They have even been known to kill and eat small animals such as the slow loris.

In 2008, 'The Thinkers Of The Jungle', by Gerd Schuster, Willie Smits and Jay Ullal, was released, with a picture of a Bornean orangutan trying to use a long pointed stick to spear a fish - one of the most intriguing examples of their well-documented use of tools.

Answer: True

The process of building a nest for the night is quite complex, and starts with selecting the right tree. Species is not important, but it must have a suitable branch structure so that the nest can be built. The first step of actual construction is to bend a number of branches to overlap each other, joining them to form the base. Next comes a layer of smaller leafy branches, referred to as the mattress, to provide a soft surface on which to rest. The 'mattress' is finished off by twining all the ends of the small branches together, so they stay in place. That's not the end of things, though. If the resources are available (and that is part of the reasoning behind tree selection), the orangutan will add 'pillows' by arranging more small leafy branches so that the leaves are together, and the stems point outward (with any sharp ends bitten off to prevent accidental injury during sleep). A 'blanket' may be arranged by leaving some large leafy branches close at hand, which can be dragged over the orangutan after it is lying down. In rainy seasons, some overhead branches may be woven together to provide a 'roof'. This sounds as if it would take a lot of time, but an adept orangutan will build the nest in around five minutes.

Day nests usually only have the foundation and 'mattress', and can be constructed much more quickly. Infants start to acquire their nest-building skills, starting at around six months of age, by beginning with a day nest.

Answer: 8 years

All of those times are significant points in the reproductive process. A female orangutan will usually have her first child at around 15 years of age. For the first four to six months the infant stays in complete contact with the mother, 24/7. Although the infant starts to be separate for short intervals at that time, it remains completely dependent on its mother until it is around two years old, at which time it starts engaging in social interactions with other juveniles. Weaning usually occurs at around four or five years of age, and the youngster is ready to start leading a more independent life. Adolescent males are likely to head out on their own, while adolescent females tend to stay with their mother, assisting in the raising of younger siblings, until they are ready to start their own family.

When that happens, they commonly set themselves up in a nearby territory, which has some overlap with the maternal territory.

Answer: Play singing

The long call, which is characteristically produced by adult males, gets its name both because it lasts for a relatively long time (up to 4 minutes) and because it carries for a long distance. It is made to attract females and to let males know that there is another male in the vicinity. (They can decide whether or not to provoke a confrontation.) The call has several stages, starting with low grumbles and proceeding to loud barking sounds before finishing with a series of sighs.

The kiss squeak is produced by orangutans of all ages and both genders, and is an indication of annoyance. It is produced by means of a sharp intake of breath through pursed lips, which produces a sound similar to that of a kiss.

The soft hoot is characteristic of infants, and indicates fear or irritation. It gets the mother's attention in either case.

Another interesting vocalisation is called the raspberry, which sounds pretty much like the human vocalisation of the same name. It is made during nest building, and seems to be intended as a way to produce saliva, as the sound is often followed by running a nest-building twig through the mouth before putting it in place.

Answer: Construction of the Batang Toru hydroelectric dam

The SOCP has primary responsibility for orangutan conservation, which includes habitat protection. In this case, there was originally strong opposition to the construction of the planned dam, because it would immediately destroy almost a tenth of the habitat of the Tapanuli orangutan, and would also create fragmented groups, separated by the infrastructure crossing through their travel areas, whose population would be below the sustainable level. There is already concern that the small population is leading to inbreeding, and that would be exacerbated by further reduction in the size of the groups.

While the SOCP opposition to this particular project is not as strong as conservationists would like, they remain fully committed to their projects to confiscate and rehabilitate orangutans which have been illegally captured, to conduct research that will increase our understanding of orangutans and their needs, and to educate the public in that regard.