Endangered SpeciesA branch of The Humanity Project

Mammals

Sumatran Orangutan

Pongo abelii

A critically endangered great ape confined to northern Sumatra, losing habitat to oil palm expansion, logging, and road development.

Illustration of a Sumatran orangutan ambassador — long shaggy reddish-orange hair, long arms and a pale narrow face — hanging by one arm in a rainforest canopy holding a fig.
Illustrated Species Ambassador — original artwork, not a photograph

Illustrated Species Ambassador

Leuser — Sumatran Orangutan

I'm Leuser, an illustrated ambassador for the Sumatran orangutan. I spend nearly my whole life above the forest floor, moving tree to tree.

One fact worth knowing
The Sumatran orangutan is critically endangered and confined to northern Sumatra, losing habitat to oil palm expansion, logging, and road development.
What I depend on
I depend on continuous canopy I can travel through, a diversity of fruiting trees through the year, and forest that roads have not cut apart.
My greatest threat
My greatest threat is deforestation for oil palm and logging.
One way you can help
Choose products with credible deforestation-free or certified sustainable palm oil sourcing, and never support tourism or media that uses captive orangutans as props.
Global endangered species →

This ambassador is an original illustration created for this project. It is an educational character, not a documentary image, and its statements follow the sourced record on this page. Artwork and rights record

Why this species matters

Orangutans reproduce more slowly than any other mammal. A population that loses adult females does not bounce back within a human lifetime, which makes every individual loss disproportionately serious.

If it disappears: Their disappearance would remove a principal seed disperser from Sumatran rainforest and end one of only three orangutan species on earth.

Conservation status

IUCN Red List
Critically EndangeredLast verified 2026-09-08
CITES
Appendix ILast verified 2026-09-08
U.S. Endangered Species Act
Endangered (foreign listing)Last verified 2026-09-08
Indonesia
Nationally protected speciesLast verified 2026-09-08

Population

Approximately 13,000–14,000 individuals remaining in northern Sumatra, based on nest-count surveys and habitat modeling.

Trend: Decreasing

As reported: IUCN Red List assessment and published Sumatran orangutan population viability analyses, 2016–2017

Source: IUCN Red List; IUCN SSC Primate Specialist Group

Uncertainty: Estimates rely on nest density surveys extrapolated to habitat area, and different studies produce somewhat different totals.

Historical: Formerly present across Sumatra and into Java; now restricted to the island's northern forests.

Fragmentation: Remaining populations are split by roads and plantations, with some subpopulations too small to be viable long term.

Range and distribution

Historic range: Much of Sumatra and, in prehistory, parts of Java and mainland Southeast Asia.

Current range: Northern Sumatra, principally the Leuser Ecosystem in Aceh and North Sumatra provinces.

Range contraction: Confined to roughly the northern tip of one island.

Regions occupied

  • Aceh, Indonesia
  • North Sumatra, Indonesia

Habitat

Primary habitat: Lowland and hill tropical rainforest, including peat swamp forest.

Breeding habitat: Females build nests in the canopy and raise a single infant for years.

Feeding habitat: Fruit-dominated canopy foraging, especially figs and mast-fruiting trees.

Habitat dependencies

  • Continuous canopy for travel
  • Reliable fruiting tree diversity
  • Low road density

Biology and ecology

A major canopy seed disperser for large-fruited rainforest trees.

Important adaptations: Almost entirely arboreal, with hooked hands and feet and enormous arm span for canopy travel.

Size
Males about 4.5 feet tall; females noticeably smaller.
Weight
Males roughly 190 pounds; females roughly 90 pounds.
Lifespan
Around 45–50 years or more in the wild.
Diet
Predominantly fruit, with leaves, bark, insects, and occasionally small vertebrates.
Reproduction
Gestation about 8.5 months.
Offspring
A single infant.
Breeding frequency
Birth intervals of roughly 8–9 years — the slowest reproductive rate of any mammal, which makes any loss of breeding females severe.
Age at maturity
Around 15 years for females.

Primary threats

  • Deforestation

    Conversion of lowland and peat forest to oil palm and pulpwood plantations is the dominant driver of decline.

  • Habitat fragmentation

    Road projects through the Leuser Ecosystem sever canopy connectivity that arboreal apes depend on.

  • Illegal collection

    Infants are taken for the pet trade, usually after the mother is killed.

  • Human-wildlife conflict

    Orangutans entering plantations and gardens are killed as crop pests.

  • Fire

    Peat and forest fires destroy habitat and kill animals unable to escape.

  • Slow reproduction

    An 8–9 year birth interval means recovery from any decline is measured in decades.

Conservation and recovery

Programs and efforts

  • Leuser Ecosystem protection and monitoring
  • Orangutan rescue, rehabilitation, and reintroduction centres
  • Roundtable on Sustainable Palm Oil certification and no-deforestation supply chain commitments
  • Community forest patrol and snare removal programs

Protected areas

  • Gunung Leuser National Park
  • Leuser Ecosystem
  • Batang Toru forest (home to the separate Tapanuli orangutan)

Legal protections

  • CITES Appendix I
  • Indonesian national protection law
  • U.S. ESA foreign listing

Measurable progress

  • Establishment of reintroduced populations in Jambi and Aceh
  • Growing corporate no-deforestation commitments in palm oil supply chains

Continuing challenges

  • Continued plantation and road expansion
  • Enforcement gaps
  • Extremely slow reproduction

How people can help

What individuals can do

  • Choose products with credible deforestation-free or certified sustainable palm oil sourcing
  • Never support wildlife tourism or media that uses captive orangutans as props

What communities can do

  • Support supply-chain transparency policies for palm oil and pulpwood importers

Educational actions

  • Use orangutan birth intervals to teach why reproductive rate governs recovery speed

Habitat support

  • Support Leuser Ecosystem protection and forest restoration

Organizations and programs to learn about

  • IUCN SSC Primate Specialist Group
  • Sumatran Orangutan Conservation Programme
  • Leuser International Foundation

Educational notes

  • A third orangutan species, the Tapanuli orangutan, was described in 2017 — a recent taxonomic discovery in a large mammal.
  • Shows how a single consumer commodity can drive a species' decline.

Sources and references