Sumatra and the Mentawai, Natuna and Riau Islands
Sumatran Orangutan, Pongo abelii, Gunung Leuser
I spent the last week of May 2015 in Sumatra and visited Way Kambas and Gunung Leuser. I returned in 2025 for three nights primarily in Way Kambas.
Way Kambas
Pen-tailed Treeshrew (Ptilocercus lowii)
Four nights in 2015 produced Pen-tailed, Sumatran &Lesser Treeshrews; Long-tailed & Southern Pig-tailed Macaques; Mitered & Sunda Silvery Langurs; Agile Gibbon; Siamang; and Sunda Slow Loris.
Horsfield’s (Javan) Flying Squirrel, Iomys horsfieldii
We saw lots of squirrels in 2015. In the daytime we found Black-striped, Plantain & Prevost’s Squirrels;Three-striped Ground Squirrel; Black-eared Squirrel; Slender Squirrel; and Black Giant Squirrel. At night we saw Javanese & Red Giant Flying Squirrels, as well as Malaysian Field Rat; and Muller’s Rat.
Siamang, Symphalangus syndactylus
Way Kambas is good for bats. In 2015 we saw Common Dayak Fruit Bat; Lesser & Minute Short-nosed Fruit Bats; Island Flying Fox; and Leschenault’s Rousette. In culverts we found roosting the rather rare Orbiculus Leaf-nosed Bat; Lesser Asian False-vampires; Lesser Woolly Horseshoe Bats; Lesser Sheath-tailed Bat; and Malayan Slit-faced Bat.
Orb-faced Roundleaf Bat, Hipposideros orbiculus
Carnivores were represented by Sunda Leopard Cat; Banded, Small-toothed; Masked & Southern Palm Civets; as well as Malay Civet. And we also saw Eurasian Wild Pig; Sambar; Southern Red Muntjac; and both Lesser & Greater Indo-Malayan Chevrotains.
Banded Palm Civet, Paguma larvata. photo Jean-Michel Bompar
Two nights in 2025 produced mainly a subset of what I saw in 2015 though I added Acuminate & Trefoil Horseshoe Bats to my park list
North Sumatra: Gunung Leuser
Sumatran Orangutans, Pongo abelii, Gunung Leuser
During three nights here in 2015 we saw Sunda Colugo; Long-tailed & Southern Pig-tailed Macaques; Thomas’s Langur; Sumatran Orangutan; and Hiller’s Slow Loris.
Hiller’s Slow Loris, Nycticebus hilleri
We also found Black Flying Squirrel; Large Flying Fox; Lesser Asian False-vampire; Small-toothed Palm Civet; and Lesser Indo-Malayan Chevrotain.
Thomas’s (North Sumatran) Langur, Presbytis thomasi
Community Reports
Way Kambas & a futile striped rabbit seach, 2025: Jon Hall, 3 nights & 25 species including Pen-tailed Tree Shrew, Acuminate Horseshoe Bat and Horsfield’s Flying Squirrel.
Siberut Island, 2025: Stuart Chapman, 3 days & 9 species including 7 endemics: Pig-tailed & Siberut Langurs, Golden-bellied Treeshrew, Mentawai Rat, Fraternal Squirrel and Siberut & Sipora Flying Squirrels.
Way Kambas, 2024: Bennett Gardner, 4 days & 30 species including Short-tailed Mongoose, Western Tarsier and a Sun Bear.
Siberut Island, Sumatra & Java, 2024: Ian Thompson, 3 weeks & 56 species including Pen-tailed Tree Shrew, Marbled Cat and Kloss’s Gibbons.
Bukit Lawang & Tapanuli, 2024: Coke Smith, 10 days & 21 species including Thomas’s & Black Sumatran Langurs plus Tapanuli & Sumatran Orangutans.
Gunung Leuser, 2024: Stuart Chapman’s note about a quick and accessible site for Sumatran Orangutan.
Sumatra primates, 2023: Sichao Ma, 2 weeks & 15 species – 13 of them primates – including Tapanuli Orangutan,Sumatran Black Langur and East Sumatran Banded Langur.
Sumatra & Java, 2023: Royle Safaris, 2 weeks & 42 species including Marbled Cat, Sumatran Orangutan and Javan Small-toothed Palm Civet.
Sumatra, Java & Bali, 2023: Royle Safaris, 17 days & 22 species including East and West Javan Langurs and Javan Small-toothed Palm Civet.
Tapanuli Orangutan, 2023: Mark Spence with species including Tapanuli Orangutan and Sumatran Black Langur.
Bintan Langurs, 2022: Mark Spence’s successful and exciting 3 days search for a Bintan Langur with other species including Silvery Langur.
Sumatran Rhino Quest, 2020-22: Royle Safaris‘ combined report of 3 adventures looking for Sumatran Rhinos, with 17 species encountered including Sumatran Tiger and – finally – Sumatran Rhino. Check out Chris Scharf on the mammalwatching podcast who was on all these trips.
Natuna Islands, 2021: Mark Spence, 1 week with mammals including Natuna Langur, Small-toothed Palm Civet, Slow Loris and a strange looking Giant Squirrel.
Way Kambas, 2019: Hugh Lansdown, 5 days & 22 species including Sun Bear, Malayan Weasel and Pen-tailed Tree Shrew.
Sumatran Rhino Trip, 2019: Royle Safaris, 3 weeks & a fascinating report of a “new” population of Sumatran Rhinos which were heard but not seen plus the presence of 26 other species detected.
Siberut, Mentawai Islands, 2018: Mark Spence, 5 days with some nice mammals including Siberut Flying Squirrel, Kloss’s Gibbon and Mentawai and Pig-tailed Snub-nosed Langurs.
Singapore, Java, Malaysia and Sumatra, 2019: Anita Ericson and Lars Petersson, 6 weeks & 63 species including – in Sumatra – Pen-tailed Tree Shrew, Lar Gibbon, Binturong and Serow.
Sulawesi and Kerinci-Seblat, Sumatra (with a bit of Bali and Java too), 2018: Tomer Ben-Yehuda, 2 weeks & 30+ species including Babirusa and Bear Cuscus.
Way Kambas (Sumatra) and Tangkoko (Sulawesi), 2018: Andreas Jonsson, 9 days & 32 species in Way Kambas, and another 5 in Tangkoko, including Pen-tailed Tree Shrew, Trefoil Horseshoe Bat and Celebes Dwarf Squirrel.
Indonesia, 2016: Richard Webb, 2 weeks & 44 species including Western Tarsier, White-bearded Gibbon, Irrawaddy Dolphin and some nice bats.
Gunung Leseur, 2016: Evan Greenspan, 10 days with species including Orangutan and Mitred Langur, but no cats.
Gunung Kerinci and Tapan Road, 2016: Richard Webb, 5 days & 13 species including Mitred Langur, Siamang and Niobe Ground Squirrel.
Way Kambas & Gunung Leuser, 2015: Jon Hall, 1 week & 48 species including Pen-tailed Tree Shrew, Sumatran Orangutan and Mitred and Thomas’s Langurs.
Way Kambas, 2014: Paul Carter, 1 week & 31 species including Pen-tailed Tree Shrew, Malaysian Slit-faced Bat, Yellow-throated Marten and a probable Marbled Cat.
Sumatra & Komodo, 2014: Royle Safaris, 2 weeks & over 50 species including Marbled Cat, Siamang and Binturong.
Way Kambas & Indonesian Borneo, 2014: Ian Loyd, Lorna Watson and Steve Morgan, 2 weeks & 36 species including Feather-tailed Tree Shrew, Malayan Tapir, some nice bats and a probable Marbled Cat and Banded Linsang.
Indonesia (Java, Sumatra, Sulawesi, Borneo and Bali), 2013: Dave Redfield and Richard White (INDRI tours), 22 days & 52 species including Pen-tail Treeshrew, Otter Civet and Mitred Langurs (all in Way Kambas, Sumatra).
Java & Sumatra, 2013: Richard Webb, 2 weeks & 38 species including all the Javan specialty primates and Javan Small-toothed Palm Civet, plus – on Sumatra – Banded Palm Civet, Flat-headed and Marbled Cats.
Sulawesi, Sumatra and a bit of Java, 2012: Dominique Brugiere, 7 weeks & plenty of mammals including Babirusa, Sulawesi Warty Pig, Anoa, Banteng and Javan Ferret Badger.
Way Kambas, 2012: Richard Webb, 1 week & 26 species including Marbled Cat(s) and a Banded Palm Civet.
Sumatra, 2011: Carmen and Torbjorn Lundqvist, 3 weeks & 27 species including Sumatran Orangutan, Thomas’s Leaf Monkeys and Mitred Langurs.
Indonesia (esp. Sulawesi), 2009: Steve Anyon-Smith, 1 month & 20 mammals including Sulawesi Tarsier and Bear Cuscus.
Greater Sundas (West Malaysia, Borneo, Sumatra, Java), 2008: Tim Mitzen, 2 months and 55 mammals including a Sun Bear and Banded Palm Civet. A full trip report is here.
Also See
RFI – Tips for Sumatra, September 2025
Suggestions for guide for Bukit Lawang, October 2024
RFI Way Kambas, May 2024
Sumatran Striped Rabbit seen on Gunung Kerinci, Novembver 2023
Checklist of the Mammals of Indonesia (March, 2020)
RFI Taman Nasional Bukit Barisan Selatan (April, 2019)
Sumatra and its mammals (January, 2015)
Indonesia Rat ID help (August, 2014)
RFI on Way Kambas, Sumatra (April, 2011).
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