What If Gone

Species → Bornean Orangutan

Bornean Orangutan

Pongo pygmaeus

between 55,000 and 104,000 individuals per the most recent estimates,…
Extinction risk Critically Endangered
Tropical forestSeed disperserCatastrophic declineExtinction
Bornean Orangutan (Pongo pygmaeus)
Photo: A.Baihaqi, Wikimedia Commons (CC BY-SA 4.0)

What if it disappeared?

Impact High
39 to 87 hours

Three-quarters of the analyzed orangutan feces contained intact seeds from 24 different plant genera, carried an average of 500 to 600 meters depending on digestive transit time (39.5 to 87 hours) — and for five of six genera tested, seeds that passed through the orangutan's gut germinated significantly better than control seeds.

Documented
Detail

Blackburn, A., Susanto, T.W. & Knott, C.D. (2020). Orangutan seed dispersal in Gunung Palung National Park, Borneo, Indonesia: dispersal quantity, germination rates, gut transit times, and dispersal distances. 7th Frugivores and Seed Dispersal Symposium.

Study based on 549 fecal samples from 36 individuals at Gunung Palung National Park (Borneo). The orangutan is one of the only animals in Borneo large enough to swallow large-seeded fruit whole, on an island with neither elephants nor rhinoceroses to fill that role — which makes its dispersal service hard to replace with another species if its population keeps declining.

Since 1950

If the orangutan really is irreplaceable for large-seeded fruit, its disappearance from more than 80% of its former range since 1950 should already be measurably slowing the regeneration of certain tree species — but no one has compared the recolonization of these species between forests where the orangutan has disappeared and forests where it still persists.

Insufficient
Detail

The decline has occurred in landscapes that were fragmented and converted to plantations, which makes it difficult to isolate the specific effect of losing the orangutan from the much larger effect of the forest itself disappearing at those same sites.

Today

A landmark study of umbrella species in Sumatra's Leuser Ecosystem, covering eight candidate species including tiger, rhinoceros, and elephant, had to exclude the Sumatran orangutan from its analysis — not for lack of interest, but because ground-based camera traps, the standard method for this kind of study, simply cannot reliably detect an almost entirely arboreal animal.

Insufficient
Detail

Ardiantiono, Deere, N.J., Ramadiyanta, E., Sibarani, M., Hadi, A.N., Andayani, N., Ginting, Y., Bull, J. & Struebig, M.J. (2024). Selecting umbrella species as mammal biodiversity indicators in tropical forest. Biological Conservation, 292, 110511.

The study concludes that the sambar deer and the Sunda clouded leopard — two far less publicized species — predict overall biodiversity better than the tiger or rhinoceros, but the methodological exclusion of the orangutan shows we don't even yet know how to compare it to the others on this specific criterion, for lack of a monitoring tool suited to its arboreal lifestyle.

Documentation

Last verified: August 10, 2026