---
title: "What the sources say about the Bornean Orangutan | AnimalTracks.wiki"
description: "63 claims from the Bornean Orangutan profile, each beside the words of the source that backs it."
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---

# What the sources say about the Bornean Orangutan (*Pongo pygmaeus*)

> 63 claims from the Bornean Orangutan profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Bornean Orangutan](https://animaltracks.wiki/animals/bornean-orangutan/)

## Ancrenaz et al. (2024). Pongo pygmaeus. The IUCN Red List of Threatened Species 2024: e.T17975A259043172.

https://doi.org/10.2305/iucn.uk.2024-1.rlts.t17975a259043172.en

| The page says | The source says |
| :--- | :--- |
| Bornean orangutans are Critically Endangered | Critically Endangered (CR) |

## Pongo pygmaeus (Bornean orangutan). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Pongo_pygmaeus/

| The page says | The source says |
| :--- | :--- |
| long arms for the canopy | Bornean orangutans have orange-red hair and long arms, which are advantageous for traveling through the canopy. |
| hands and feet that both grip | Bornean orangutans grasp with both their feet and hands, which suites their arboreal life. |
| Primary lowland rainforest, peat swamp forest, and dipterocarp forest on Borneo | They generally live in the old growth forests ranging from the lowland swampy areas to the dipterocarp forests. The peat swamps and flood-prone dipterocarp forests produce more fruit than the dry dipertocarp forests ... Bornean orangutans inhabit the primary tropical rainforest and secondary forest at lower elevations |
| Long arms that help it travel through the canopy | Bornean orangutans have orange-red hair and long arms, which are advantageous for traveling through the canopy. |
| hands and feet that can both grasp | Bornean orangutans grasp with both their feet and hands, which suites their arboreal life. |
| Bornean orangutans rarely come down to the forest floor | Bornean orangutans are arboreal and rarely descend to the ground. |
| rather than on their knuckles | When walking quadrupedally, they walk on their fists rather than their knuckles, unlike other great apes. |
| A Bornean orangutan cannot swim, so rivers and other waterways box in where it can travel | Bornean orangutans cannot swim which make rivers and other water sources impassable boundaries, limiting their range. (note: "so" is the source's own link ("which make")) |
| a Bornean orangutan's nest platform sits 12 to 18 meters (40 to 60 feet) off the ground | Bornean orangutans sleep in nest platforms made of vegetation 40 to 60 feet off the ground. (note: 40 to 60 feet converts to 12.2 to 18.3 meters) |
| Two Kinds of Grown Male | Bornean orangutans exhibit bimaturism, or two different forms of mature males. |
| Adult male Bornean orangutans average about 87 kilograms (192 pounds) | males having an average height and weight of 970 mm and 87 kg respectively (note: 87 kg converts to 192 lb (ADW's own table: 191.63 lb). Within NZP's current wild adult male range for orangutans, 77 to 100 kg, so the two agree) |
| females about 37 kilograms (82 pounds) | females averaging 780 mm and 37 kg, respectively (note: 37 kg converts to 82 lb. Within NZP's current wild adult female range for orangutans, 36 to 54 kg) |
| Males come in two forms: flanged males with wide cheek pads, and unflanged males that are the same size as females and look much like them | Males also develop large cheek pads known as flanges ... These two types of males are denoted as being either flanged and unflanged. ... Unflanged males look much more like the females as they are the same size |
| Males aged 8 to 15 are generally unflanged and become flanged between 15 and 20 | Males between 8 and 15 years of age are generally unflanged and become flanged between 15 and 20. |
| Both kinds of male father offspring | Both types of adult male orangutans reproduce in the population. |
| unflanged males that hear it flee the area | when unflanged males hear long-calls they flee the area |
| Gardeners of the Forest | Bornean orangutans play such a crucial role in seed dispersal that they have been given the title "gardeners of the forest". |
| Bornean orangutans have been recorded eating more than 500 plant species | Bornean orangutans have been documented eating more than 500 plant species as part of their diet. |
| fruit makes up more than 60 percent of their diet | Fruits make up more than 60% of their total dietary intake |
| That makes them "gardeners of the forest," spreading seeds, especially large ones that smaller animals cannot disperse | Since fruits make up more than 60% the Bornean orangutan diet, they play a vital role in seed dispersal, especially for the larger seeds which cannot be dispersed by smaller animals. Bornean orangutans play such a crucial role in seed dispersal that they have been given the title "gardeners of the forest". |
| The Bornean orangutan cannot swim, so rivers and other waterways limit where it can travel | Bornean orangutans cannot swim which make rivers and other water sources impassable boundaries, limiting their range. (note: "so" is the source's own link ("which make")) |
| A Bornean orangutan's nest platform, made of vegetation, sits 12 to 18 meters (40 to 60 feet) off the ground | Bornean orangutans sleep in nest platforms made of vegetation 40 to 60 feet off the ground. (note: 40 to 60 feet converts to 12.2 to 18.3 meters) |
| The pads, called flanges, grow on some adult males | Males also develop large cheek pads known as flanges ... Bornean orangutans exhibit bimaturism, or two different forms of mature males. These two types of males are denoted as being either flanged and unflanged. |
| where they generally inhabit swampy and hilly tropical rainforests | generally inhabits swampy and hilly tropical rainforests |

## Orangutan. San Diego Zoo Wildlife Alliance.

https://animals.sandiegozoo.org/animals/orangutan

| The page says | The source says |
| :--- | :--- |
| Borneo's biggest mammal in the trees | These shaggy red apes are the largest arboreal mammal and the only great apes found in Asia. (note: The quote ranks orangutans, all three species. The Bornean orangutan is the only orangutan on Borneo (SDZoo: "Bornean orangutan: Native to the island of Borneo"), so the rank is narrowed to Borneo rather than claimed for the species worldwide; "mammal" is kept) |
| Wild figs, durian, and other forest fruit | Orangutans eat lots of ripe fruits ... Figs, along with fruit of the durian tree, are most common. |
| leaves, bark, insects, bird eggs, and honey when fruit is scarce | When fruits are scarce, they eat leaves, flowers, bark, honey, termites, ants and other insects, and even bird eggs. |
| An orangutan's arms stretch out longer than its body, more than 2 meters (7 feet) from fingertip to fingertip | Their arms stretch out longer than their bodies—measuring over 7 feet (2 meters) from fingertip to fingertip. |
| Orangutans also use leafy branches to shelter from rain and sun, and sometimes drape large leaves over themselves like a poncho | Orangutans also use leafy branches to shelter themselves from rain and sun, and sometimes they drape large leaves over themselves like a poncho! |
| Orangutan males average 136 centimeters (54 inches) in height and females 114 centimeters (45 inches) | Height: Females, average 45 inches (114 centimeters); males, average 54 inches (136 centimeters) (note: San Diego Zoo's page covers all three orangutan species, so the figure is stated for orangutans, not as Bornean. ADW (2013) gives Bornean average heights of 970 mm and 780 mm, which disagree; the current page wins (docs/fact-check.md, Check the date).) |
| When males fight, they charge at each other and break branches, and if that doesn't scare one away, they grab and bite each other's cheek pads or ears until one gives up and runs away | When males fight, they charge at each other and break branches. If that doesn't scare one of them away, they grab and bite each other on the cheek pads or ears until one of them gives up and runs away! |
| Orangutan diets center on wild figs, durian, and other forest fruit | Orangutans eat lots of ripe fruits ... Figs, along with fruit of the durian tree, are most common. |
| backed up by leaves, bark, insects, bird eggs, and honey when fruit runs short | When fruits are scarce, they eat leaves, flowers, bark, honey, termites, ants and other insects, and even bird eggs. |
| Their arms stretch out longer than their bodies, measuring more than 2 meters (7 feet) from fingertip to fingertip | Their arms stretch out longer than their bodies—measuring over 7 feet (2 meters) from fingertip to fingertip. |
| Orangutans also shelter from rain and sun with leafy branches, and sometimes drape large leaves over themselves like a poncho | Orangutans also use leafy branches to shelter themselves from rain and sun, and sometimes they drape large leaves over themselves like a poncho! |
| When males fight, they charge and break branches, and if that doesn't scare one away, they grab and bite each other's cheek pads or ears until one gives up | When males fight, they charge at each other and break branches. If that doesn't scare one of them away, they grab and bite each other on the cheek pads or ears until one of them gives up and runs away! |

## Orangutan. Smithsonian's National Zoo and Conservation Biology Institute.

https://nationalzoo.si.edu/animals/orangutan

| The page says | The source says |
| :--- | :--- |
| a long call that can be heard a kilometer or more away | It can be heard a kilometer or more away (more than half a mile). (note: NZP speaks of orangutans; ADW's Bornean account says "The long-call can be heard from several kilometers away in the right conditions", so the lower figure holds for this species) |
| for an ape that normally moves cautiously, climbing and walking through large trees to spread its weight | Orangutans can brachiate — swing hand over hand — but they normally move cautiously through large trees by climbing and walking. This allows them to distribute their weight among the branches. (note: vibe.reason; the words before "for" describe the track) |
| Built for Life in the Trees | Orangutans are the largest arboreal mammals and are very well adapted to life in the trees |
| Orangutans are the largest arboreal mammals | Orangutans are the largest arboreal mammals and are very well adapted to life in the trees |
| it has long curved fingers and toes for grasping | They have grasping hands and feet with long curved fingers and toes. |
| Its hands make it graceful and swift when swinging but slow and awkward on the ground | Orangutans' hands make them graceful and swift while swinging, but it makes walking on the ground very slow and awkward. |
| Orangutans can swing hand over hand, but they normally move cautiously, climbing and walking through large trees to spread their weight across the branches | Orangutans can brachiate — swing hand over hand — but they normally move cautiously through large trees by climbing and walking. This allows them to distribute their weight among the branches. |
| On the ground, they use all four limbs, supporting themselves on the sides of clenched fists | When on the ground, they use all four limbs, supporting themselves on the sides of clenched fists |
| Orangutans usually build a fresh nest each night, though they sometimes rebuild an old one | They usually build and sleep in a fresh nest each night, but they will sometimes re-enter or rebuild an older nest. |
| "Orangutan" means "person of the forest" in the Indonesian and Malaysian languages | Orangutan means "person of the forest" in the Indonesian and Malaysian languages. |
| the presence of a fully mature dominant male may suppress another male's pads, and in some cases a wild male may never develop them | The presence of a fully mature dominant male may suppress secondary sexual characteristics (long hair, face pads, beards and enlarged throat sacs) in other less dominant males, and, in some cases, a wild male orangutan may never develop cheek pads. |
| A male Bornean orangutan's median life expectancy is about 27 years | The median life expectancy for male Bornean orangutans is about 27 years |
| there is not enough data to give one for females | There is not enough available data on the life expectancy of female Bornean orangutans. |
| Cheek Pads and the Long Call | large cheek pads, which demonstrate genetic fitness and amplify their long calls. (note: "typically" in the source qualifies whether males develop pads; a flanged male has them by definition) |
| A Face Built to Be Heard | large cheek pads, which demonstrate genetic fitness and amplify their long calls. (note: "typically" in the source qualifies whether males develop pads; a flanged male has them by definition) |
| A flanged male's cheek pads amplify his loud, deep long call | large cheek pads, which demonstrate genetic fitness and amplify their long calls. ... a loud, deep long call used typically by males for long-distance communication. (note: "typically" in the source qualifies which sex gives the call; ADW: the long-call is "performed only by flanged males") |
| which can be heard a kilometer or more away | It can be heard a kilometer or more away (more than half a mile). (note: NZP speaks of orangutans; ADW's Bornean account says "The long-call can be heard from several kilometers away in the right conditions", so the lower figure holds for this species) |
| their numbers have dropped by more than half over the past 60 years | Their population levels have dropped more than 50 percent over the past 60 years |
| their habitat has shrunk by more than 80 percent in the past 20 | their habitat has declined by over 80 percent in the past 20 years. |
| Yes. Orangutans are the largest arboreal mammals | Orangutans are the largest arboreal mammals and are very well adapted to life in the trees |
| they grasp with long curved fingers and toes | They have grasping hands and feet with long curved fingers and toes. |
| Their hands make them graceful and swift while swinging but slow and awkward walking on the ground | Orangutans' hands make them graceful and swift while swinging, but it makes walking on the ground very slow and awkward. |
| Orangutans usually build and sleep in a fresh nest each night, but sometimes re-enter or rebuild an older nest | They usually build and sleep in a fresh nest each night, but they will sometimes re-enter or rebuild an older nest. |
| They demonstrate genetic fitness and amplify the male's long call | Males also typically develop large cheek pads, which demonstrate genetic fitness and amplify their long calls. (note: NZP's "typically" qualifies which males develop pads, and the FAQ's "grow on some adult males" carries it; the pads themselves "demonstrate genetic fitness".) |
| which is audible a kilometer or more away | It can be heard a kilometer or more away (more than half a mile). |
| Bornean orangutans live in both the Malaysian and Indonesian parts of the island of Borneo | Orangutans live on the Indonesian island of Sumatra and in both the Malaysian and Indonesian portions of the island of Borneo. (note: NZP's page covers all orangutans; the Borneo half of its range is the Bornean orangutan's (SDZ: "Bornean orangutan: Native to the island of Borneo").) |