Tapanuli Orangutan

## About

A male Tapanuli orangutan.

The Tapanuli orangutan ***(Pongo tapanuliensis)*** is a large species of arboreal orangutan that lives in the lush rainforests of south Tapanuli, Sumatra. Tapanuli orangutans share an appearance with other orangutan species, having long orange or red hair as well as greyish-black skin. Sexual dimorphism is very apparent in all the three orangutan species, the males of this species in particular have flanges on their faces, which give their heads an enlarged appearance. All male orangutans of every species have these face flanges however, Tapanuli orangutan's flanges are generally smaller than that of the Bornean orangutan ***(Pongo pygmaeus)***. Interestingly enough, both sexes of Tapanuli orangutans possess beards despite their relatives only having beards present in the males. Female Tapanuli orangutans are much smaller than males and also lack the characteristic face flanges of the males. Female Tapanuli orangutans also have shorter hair, lacking the iconic long strands of fuzzy orange-red hair that blanket male orangutans. Tapanuli orangutan females can reach just under 1.23m (4ft) in height and weigh around 40-50kg (88-110lbs), whereas males can grow to be 1.37m (4.3ft) in height and weigh 70-90kg (150-200lbs).

## Diet

According to the New England Ape Conservancy, Tapanuli orangutans are known to eat a large variety of plant matter. Specifically, fruits such as mangoes, lychees, figs and even wild durians. Unlike any other orangutan species, the Tapanuli orangutan also consume caterpillars and conifer cones.

## Conservation Status

The Tapanuli orangutan is threatened by the deforestation of its home. This deforestation is attributed to the growing palm oil industry in Southeast Asia, in which millions of trees are cut down and replaced with uniform rows of palm trees. Tapanuli orangutans are currently recognised as critically endangered by the IUCN. Tapanuli orangutans are also put at dire risk by the illegal wildlife trade, which is operated very prolifically in Southeast Asia. Overall, Tapanuli orangutans are being put in massive amounts of danger thanks to humans, and if no actions are taken soon the Tapanuli orangutan could very well end up extinct in the near future.

## Range and Population

Despite the orangutan only being discovered in 1997, the WWF has a great understanding of the Tapanuli orangutan's population and know that the species is currently in a dire state with only 800 individuals remaining. This tiny population is attributed to the Tapanuli orangutan living in high human-wildlife conflict zones. In fact, the skull of a male Tapanuli orangutan that was recovered after it was killed in a human-wildlife conflict lead to multiple different characteristics between this skull and other orangutan species. As for their habitat, Tapanuli orangutans live in the 1,000 km2 (390 sq mi) zone just South of Lake Toba, Sumatra. The entire species population can be found restricted in this area, living on highland mountainous elevations of up to 300-1,300 m (980-4,300 ft) in dense rainforests and subtropical forests. Unfortunately due to their poor population and restricted range, the Tapanuli orangutan is highly susceptible to inbreeding depression, leading to less genetically diverse orangutans. The construction of a hydroelectric dam in the Tapanuli orangutan's range is further reducing their range and even possibly their population size. Batang Toru hydroelectric dam aims to reduce the carbon emissions in the area, this is a great way of creating power sustainably however, it may spell disaster for the remaining Tapanuli orangutans.

## Behaviour

Tapanuli orangutans act differently to other orangutan species, most noticeably the Tapanuli orangutan will spend more time time in the trees, being exclusively arboreal. Out of the 3,000 hours of observation, Tapanuli orangutans did not once come to the ground. This arboreal reliance is most likely due to the abundance of Sumatran tigers ***(Panthera tigris sumatrae)*** in the area which hunt and eat orangutans if given the chance. Tapanuli males also possess a distinct call from other orangutans, being more high-pitched and having more pulses. This call will also last longer than the other orangutan species.

### Relationship with Humans

Tapanuli orangutans are constantly being caught up in wildlife conflicts between humans. This unfortunate circumstance is due to the further human encroachment on vital orangutan territory. The first holotype of a Tapanuli orangutan was actually retrieved from an individual who was fatally injured by locals. Humans and Tapanuli orangutans have a complicated relationship and generally, orangutans do poorly when situated near human populations.

## In Captivity

Though both Bornean orangutans and Sumatran orangutans ***(Pongo abelii)*** are both found plentifully in zoos worldwide, no records of Tapanuli orangutans in captivity exist.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/120588639/120588662
* Tapanuli Orangutan | Wikipedia - https://en.wikipedia.org/wiki/Tapanuli\_orangutan#Taxonomy
* Batang Toru Hydropower Project | Wikipedia - https://en.wikipedia.org/wiki/Batang\_Toru\_hydropower\_project
* Tapanuli Orangutan | WWF Stories - https://www.worldwildlife.org/stories/new-species-of-orangutan-announced
* Orangutan | WWF - https://www.worldwildlife.org/species/orangutan
* Tapanuli Orangutan | New England Ape Conservancy - https://neprimateconservancy.org/tapanuli-orangutan/