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Text and photos by Nick Baker, unless credited to others.
Copyright ゥ Ecology Asia 2024







Mentawai Langur

Family : Cercopithecidae
Species : Presbytis potenziani

Head-body length : no data 
Tail length : no data 
Weight : no data 

Presbytis potenziani (Golden-bellied Mentawai Island Langur or simply 'Mentawai Langur') inhabits the islands of Sipora, Pagai Utara and Pagai Selatan (including Sinakak) which form part of the Mentawai island group. These elongated islands lie around 90-120 km off the western coast of Sumatra, separated by a deep trench up to ~1700 metres deep. To the northwest is the island of Siberut. 

Geologically the Mentawai Islands form part of an outer-arc complex within one of the world's most active subduction zones; the connection of this island group to Sumatra was severed more than 500,000 years ago thereby allowing unique primates to evolve in isolation.

Presbytis potenziani inhabits primary and tall secondary lowland (wet evergreen) forest. Ecological studies (home range size, canopy use, activity patterns, diet etc.) of the closely-related Siberut Langur (Presbytis siberu), formerly considered a subspecies of Presbytis potenziani, were undertaken in northern Siberut (Hadi et al, 2011). Updated ecological studies of Presbytis potenziani sensu stricto are probably required.

Presbytis potenziani exhibits the arboreal agility typical of other Presbytis langurs, confidently leaping across large gaps in the forest canopy. The species is known to use all levels of the forest, but occasionally they descend to the ground if necessary. Their diet comprises leaves, fruits, seeds and flowers.

Adult Mentawai Langur are of striking appearance, with rich dark reddish-brown fur on the chest, belly and upper arms, and white fur on the forehead, cheeks and throat. The crown is black, as is the rest of the body. The tail is long and very slender. In common with other Presbytis, infants are born all white.

This beautiful langur is categorised as Critically Endangered by IUCN with populations having been in decline over many decades. Major threats to its survival include habitat loss (forest clearance and conversion to oil palm) and over-hunting (Setiawan et al, 2020).

Figs 1 and 2Adult male encountered one morning in degraded primary forest on South Pagai island in 2023. 

Fig 3 : Typical forest habitat on South Pagai Island.

All photos thanks to Andie Ang.

References :

Hadi, S., Ziegler, T., Waltert, M. et al.  (2011)  Habitat Use and Trophic Niche Overlap of Two Sympatric Colobines, Presbytis potenziani and Simias concolor, on Siberut Island, Indonesia. Int J Primatol 33, 218232 (2012)

Setiawan, A., Quinten, M, Cheyne, S., Traeholt, C. & Whittaker, D. (2020). Presbytis potenziani. The IUCN Red List of Threatened Species 2020.

Links :

IUCN assessment (2020)


Fig 1

ゥ  Andie Ang

Fig 2

ゥ  Andie Ang

Fig 3

  ゥ  Andie Ang