Its common name is based on two separate local words, orang 'people; person' and hutan 'forest', derived from Malay,[4] and translates as 'person of the forest'.

[9] An orangutan will break off a tree branch that is about a foot long, snap off the twigs and fray one end with its teeth.

[11] When the fruit of the Neesia tree ripens, its hard, ridged husk softens until it falls open.

Inside are seeds that the orangutans enjoy eating, but they are surrounded by fiberglass-like hairs that are painful if eaten.

[10] A Neesia-eating orangutan will select a five-inch stick, strip off its bark, and then carefully collect the hairs with it.

To deal with this, their locomotion is characterized by slow movement, long contact times, and an impressively large array of locomotors postures.

Orangutans have even been shown to utilize the compliance in vertical supports to lower the cost of locomotion by swaying trees back and forth and they possess unique strategies of locomotion, moving slowly and using multiple supports to limit oscillations in compliant branches, particularly at their tips.

[1] The World Wide Fund for Nature is thus carrying out attempts to protect the species by allowing them to reproduce in the safe environment of captivity.

During this time, orangutans still have constant contact with their mothers, yet they develop a stronger relationship with peers while playing in groups.

Both males and females are usually considered healthy even at the end of their lifespans and can be identified as such by the regular abundance of hair growth and robust cheek pads.

[17] The Sumatran orangutan is more social than its Bornean counterpart; groups gather to feed on the mass amounts of fruit on fig trees.

[18] Male Sumatran orangutans sometimes have a delay of many years in the development of secondary sexual characteristics, such as cheek flanges and muscle mass.

[7] Nonja, thought to be the world's oldest orangutan in captivity or the wild at the time of her death, died at the Miami MetroZoo at the age of 55.

[23][24] Insects are also a huge part of the orangutan's diet; the most consumed types are ants, predominantly of the genus Camponotus (at least four species indet.).

[24] Their main diet can be broken up into five categories: fruits, insects, leaf material, bark and other miscellaneous food items.

[24] When there is low ripe fruit availability, Sumatran orangutans will eat the meat of the slow loris, a nocturnal primate.

[26] The Sumatran orangutan genome was sequenced in January 2011, based on a captive female named Susie.

[27] Sumatrans encounter threats such as logging (both legal and illegal), wholesale conversion of forest to agricultural land and oil palm plantations,[30] and fragmentation by roads.

[1] As of 2017, approximately 82.5% of the Sumatran orangutan population was strictly confined to the northernmost tip of the island, in the Aceh Province.

[1] While poaching generally is not a huge problem for the Sumatrans, occasional local hunting does decrease the population size.

For commercial aspects, hunts for both dead or live specimens have also been recorded as an effect of the demand by European and North American zoos and institutions throughout the 20th century.

In the wild, Sumatran orangutans only survive in the province of Nanggroe Aceh Darussalam (NAD), the northernmost tip of the island.

A survey in the Lake Toba region found only two inhabited areas, Bukit Lawang (defined as the animal sanctuary) and Gunung Leuser National Park.

[32] Bukit Lawang is a jungle village, 90 kilometres (56 mi) northwest of Medan, situated at the eastern side of Gunung Leuser National Park.

The rangers were trained to teach the orangutans vital jungle skills to enable them to reintegrate into the forest, and provided additional supplementary food from a feeding platform.

A successful breeding program has been established in Bukit Tiga Puluh National Park in Jambi and Riau provinces.

Two strategies that are recently being considered to conserve this species are 1) rehabilitation and reintroduction of ex-captive or displaced individuals and 2) the protection of their forest habitat by preventing threats such as deforestation and hunting.

The former was determined to be more cost efficient for maintaining the wild orangutan populations, but comes with longer time scale of 10–20 years.

[36] Orangutans have large home ranges and low population densities, which complicates conservation efforts.

Sumatran orangutan will commute seasonally between lowland, intermediate, and highland regions, following fruit availability.