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Sunda slow loris

Nycticebus coucang (Boddaert, 1785)


Are slow loris, slow?

The Sunda slow loris (Nycticebus coucang) is a type of arboreal and nocturnal primate that is native to Singapore, western Malaysia, southern Thailand and some parts of Indonesia. It is a rare and highly elusive species in Singapore, with less than 50 sightings in the past decade.

And to answer the question… slow loris may look slow, but it is actually capable of short bursts of rapid movement when hunting prey or escaping from predators!


Global distribution

The Sunda slow loris is native to the Southeast Asia region, specifically in Sumatra, Batam, Galang, Pulau Tebingtinggi, Great Natuna, Peninsular Malaysia, Pulau Tioman, southern Thailand and Singapore. [1] [2]

global distribution map.PNG

Map showing the global distribution of Sunda slow loris (orange shaded area). Image from The IUCN Red List of Threatened Species global distribution map.

Distribution in Singapore
As the Sunda slow loris is highly elusive and no study is done on the species, the data on the species distribution is limited. So far, it is found that the species is restricted to the forests of Singapore’s rainforest nature reserves including the Bukit Timah Nature Reserve and Central Catchment Nature Reserve, and Pulau Tekong. 
If you have the good fortune to spot a slow loris in Singapore, please share the information with Mammals Sightings in Singapore! Animal sightings are important and will definitely be useful for both formal research and public education purposes alike!


Conservation status of the Sunda slow loris. Image captured from The IUCN Red List of Threatened Species.

Under The IUCN Red List of Threatened Species, the conservation status of the Sunda slow loris is listed as “vulnerable”. The Nycticebus taxon, including the Sunda slow loris species, is also listed under the Convention on International Trade in Endangered Species of Wild Dauna (CITES) Appendix I. This means that absolutely NO trade of this species is permitted.

The vulnerability of the Sunda slow loris is possibly due to the combinations of the various threats listed below: [4] [5] [6] [7] [2]

  1. Habitat loss: Sunda slow loris may not as affected to habitat loss as other primate species as this species is relatively more adaptable to anthropogenic habitats. However, severe loss of forest in Sumatra has negative impacts on the species.
  2. Habitat fragmentation: fragmentation resulting from habitat degradation and urbanization has led to restricted species dispersal due to the loss of continuous canopy cover to move from tree to tree.
  3. Consumed as traditional medicine. In Indonesia, it is also believed that slow loris has healing effects and is taken as traditional medicine.
  4. Illegal pet trades: Due to its cute appearance, Sunda slow loris is commonly caught and sold as pets throughout Southeast Asia. However, they are not suitable to be kept as pets due to the species ecological and biological needs, thus threatening their survivability.

Out of the above, illegal pet trades is the most severe threat. Oftentimes, the teeth are pulled out or clipped which causes infection and even death in certain cases. They do not make suitable pets and are very difficult to care for. Environmental stress, shock, improper handling and inadequate nutrition are common causes of the eventual death of individuals. Even if the individual managed to survive, lack of teeth makes reintroduction into the wild impossible.

Missing video

Threats in Singapore

According to the Singapore Red Data Book, the Sunda slow loris is critically endangered in Singapore. [8]  The exact population size is unknown due to it being very elusive and the presence of exotic, released pets. [9]  While the number of sightings of this species have increased in the recent decades, it may be due to the increasing fieldwork done in the forests or illegal smuggling of the Sunda slow loris into the island state. Habitat loss and fragmentation have also put the species under serious threats. [10] [3]  The numerous cases of road kills in Singapore as individuals attempted to cross canopy gaps highlighted the importance of connectivity.

Carcass of Sunda slow loris along Mandai Road in 2014. Photo taken by Chan Sow Yan. (Pending permission)

Conservation Efforts in Singapore

To curb down on illegal pet trade in Singapore, legislations, such as the Endangered Species (Import and Export) Act, have been strengthened. There is also an increase in enforcement efforts. [11]  In addition, the Agri-Food and Veterinary Authority of Singapore (AVA) and the Animal Concerns Research and Education Society (ACRES) cooperate to conduct raids on the premises of wildlife traders and also to rescue slow loris from residential areas. After being rescued or confiscated, the slow loris undergo rehabilitation in a wildlife sanctuary and their conditions will be assessed for the suitability to be released back into the wild. However, the lack of teeth makes reintroduction into the wild impossible. Two of such Sunda slow loris can be found in Singapore’s Night Safari, donated by AVA.

The following screenshot shows the follow-ups actions taken against the parties involved in the illegal sales of the slow lorises in the video above.

Screenshot of ACRES updates.PNG

How YOU can help!

Slow lorises are cute, but they are cuter in the wild! Play your part in putting a stop to illegal pet trade of slow loris by notifying ACRES when you come across anyone in possession of the slow loris be it pet owners or sellers. ACRES can be reached via their 24-hours wildlife rescue hotline 97837782 or

More importantly, we can’t save what we don’t know. Read on to find out more about the distribution, ecology, biology and many other interesting facts about slow loris. Spread the knowledge and do your part in the conservation of this primate species!


Comparison with slender loris
Slender loris (Loris) is closely related to the slow loris. So how do we distinguish between these two close-related species?

1. Slender loris is native to India and Sri Lanka, while slow loris is native to the Southeast Asia region.2. On average, slow loris has a longer and bulkier trunk compared to slender loris.3. Slow loris has smaller ears than slender loris.

slender slow.jpg
Comparison between slow loris and slender loris

4. While both have dark fur around the eyes, the coloration patterns differ. Slow loris has a white stripe separating the eye rings which broadens and fades out onto the forehead above and widens and extends to the tip of the nose.

Coloration patterns around the eyes differ between the slender loris (middle two) and the slow loris (top and bottom).

Comparision with other Nycticebus species

To differentiate between the various species within the Nycticebus taxon, we can look at the facial marking patterns. The facial marking pattern for N. coucang is marked out in red in the image below.

Facial marking patterns occurring in lorises.

Biology and Ecology

The Sunda slow loris is typically found in continuous canopy tropical rainforests. [7] [12] This species is highly territorial and solitary, living singly or in pairs. The overlapping ranges of adults are between 4m to 250m.  [13] [14]

The Sunda slow loris has a high-energy diet, consisting of molluscs, birds’ eggs, insects and fruits.  [15] [13]

Behaviour [14]

MovementWalk deliberately, habitually holding on with three extremities at a time
Territorial markingMark their territories with urine (highly territorial)
VocalizationLow buzzing hiss or growl when antagonized; high pitch rising contact call and high whistles by females during oestrus; clicks and squeaks by infants when disturbed; ultrasonic vocalizations outside of human hearing range when exploring new environments
RestingSleeps in a ball in branches or foliage
MatingFemale hangs from a branch and vocalize while the male holds the female and the branch and copulate with her
Caring for the youngInfants are carried by both parents
GroomingSpread self-produced toxin across their bodies using the toothcomb
Predator avoidanceGo into hiding
Threatened by predatorsBite, roll out and drop from the trees or roll into a ball to expose its toxic saliva-covered fur
Antagonistic behaviourAttacks, threats, assertion, pursuits, subordination



Binomial: Nycticebus coucang (Boddaert, 1785)  [16]
Common name: Sunda slow loris
Nycticebus = night (“nyktos”) monkey (“kêbos”) in Ancient Greek. It is named as such for its nocturnal behaviour.
coucang = kukang, Indonesian word for "lemurs", given due to its close resemblance to lemurs.

In different areas, the Sunda slow loris is commonly known as: greater slow loris, malu-malubukang, Kalamasan, Kuskus, kongkang, kera duku or ling lom

Nycticebus brachycephalus Sody, 1949
Nycticebus buku Robinson, 1917
Nycticebus coucang (Boddaert, 1785) 
[15]  ssp. coucang
Nycticebus hilleri Stone & Rehn, 1902
Nycticebus insularis Robinson, 1917
Nycticebus malaiana Anderson, 1881
Nycticebus natunae Stone & Rehn, 1902
Nycticebus sumatrensis Ludeking, 1867
Nycticebus tardigradus (Raffles, 1821)

Type specimen

The Sunda slow loris was first described by Dutch naturalist Pieter Boddaert in 1785, under the name Tardigradus coucang, based on the “tailless Macauco” described by Thomas Pennant in 1781 and Vosmaer’s description of “Le paresseux pentadactyle du Bengale”. [15]  This was later found to be based on two distinguishable forms – Sunda slow loris and Bengal slow loris respectively. During the taxonomic revision, the Bengal slow loris was taken as the type of coucang. However, it is highlighted that the type should be the Sunda slow loris according to the general accepted custom of selecting the form first quoted under the name of a species. This type specimen is from Malacca, Malaysia. [18]

type specimen.png
The original description of the Sunda slow loris.

The classification of the Sunda slow loris Nycticebus coucang is listed below. Taxons are listed from the most to the least inclusive. Taxonomic ranks are omitted as they do not contain meaningful taxonomic information.







Nycticebus coucang

Taxonomic history

Previous classifications of the species and subspecies within the Nycticebus taxon were mainly based on the phylogenetic species concept sensu Wheeler and Platnick (2000). Under this species concept, species are “the smallest aggregation of (sexual) populations or (asexual) lineages diagnosable by a unique combination of character states”. Consistently distinguishable morphological differences, such as body size, head forks and pelage colour, are used to draw species and subspecies boundaries.

However, delimiting species and subspecies proved to be difficult due to the high degree of morphological similarities. This results in the taxon having a complex taxonomic history and several classifications exist. [19] [20] [21] [22] [1] [23] [24] [25]

The Sunda slow loris was first described by Dutch naturalist Pieter Boddaert in 1785, under the name Tardigradus coucang. In 1812, Éthenne Geoffroy Saint-Hilaire defined the genus Nycticebus. [26]  Subsequently, the slow loris were cited by most as Nycticebus tardigradus, until it was clarified in 1902 that Linnaeus’s name tardigradus actually referred to a slender loris. [27]
Between late 1700s to early 1900s, various researchers have delimited, named and described the slow loris, each suggesting different number of species within the Nycticebus taxon. The turning point came in 1939, when Reginald Innes Pocock consolidated all the slow lorises into a single species, Nycticebus coucang. [28] Since then, there had been numerous taxonomic revisions as new species and subspecies are delimited.

In 1971, Groves established N. pygmaeus as a separate species, while dividing N. coucang into four subspecies. Subsequently, Groves opined that there were three slow loris species and N. coucang had three subspecies. [20]  In the most recent taxonomic revision in 2010, the three subspecies were promoted to species status – the Sunda slow loris (N. coucang), the Javan slow loris (N. javanicus) and Bornean slow loris (N. menagensis). [29]


Slow loris Nycticebus fall under the taxon Lorisdae, with a history dating back to the Miocene. They are strepsirrhine primates and are related to other lorisoids, including slender lorises (Loris), angwantibos (Arctocebus), pottos (Perodicticus) and galagos (Galagidae). [30] [31]

phylogenetic tree.jpg
Phylogenetic tree adapted from Perelman et al., 2011 and Seiffert et al., 2005.

Molecular clock analysis suggests that slow speciation of the slow loris started about 10 million years ago. Today, there are nine recognized species within the taxon.

As species and subspecies delimitation were largely morphology-based, research on phylogenetic relationships were carried out to determine whether such classifications were consistent with evolutionary relationships. Consequently, there have been several taxonomic revisions made based on molecular analysis. 
[32] [33]
In the first phylogenetic study of the Nycticebus taxon, 15 specimens (8 N.coucang, 6 N. intermedius and 1 N. pygmaeus) obtained from Yunnan Province, China and North Vietnam were used (specific locality unknown). Molecular phylogenetic trees were constructed, with unweighted pair group and neighbour-joining as the optimality criteria.
[33]  The results showed that the evolution morphology and mitochondrial DNA in the slow loris are consistent. The results were also coherent with the existing established separation of the Sunda slow loris and Pgymy slow loris.

phylogenetic tree1.jpg
Phylogenetic trees by a) unweighted pair group and b) neighbour joining methods. Image from Zhang et al., 1993, with annotations by Sim Hui Min.

In more recent phylogenetic studies, the relationships of species under the Nycticebus taxon cannot be accurately identified and varies with different regions of the mitochondrial DNA used for analyses.
[32] [34]

Useful Link

General information:

  1. Sunda slow loris in Encyclopedia of Life
  2. Sunda loris in GenBank Database
  3. Sunda loris in The IUCN Red List of Threatened Species

Conservation efforts:

  1. Tickling is Torture campaign
  2. Wildlife Alliance
  3. Little Fireface Project


Images and videos used in this wikispace, with credits duly given.

[i1] “Slow Loris” by Anup Shah,

Section 1: Are slow loris, slow?:
[v1] Video cut from “Slow movement of slow loris” by Little Fireface Project. Little Fireface Project YouTube Channel, 1 Nov 2013. URL: (Accessed on 20 Nov 2016).

Section 2: Distribution
[i1] “IUCN Red List Map of Nycticebus coucang” by IUCN. URL: (Accessed on 2 Nov 2016).

Section 3: Threats
[i1] “IUCN Red List of Threatened Species – Nycticebus coucang” by IUCN. URL: (Accessed on 2 Nov 2016).
[v1] “The truth behind the slow loris pet trade and ‘cute’ tickling slow loris videos” by International Animal Rescue. International Animal Rescue YouTube Channel, 9 Jun 2015. URL: (Accessed on 2 Nov 2016).
[i2] “Carcass of Sunda slow loris along Mandai Road in 2004” by Chan Sow Yan.

Section 4: Conservation Efforts in Singapore
[v1] “ACRES Sunda slow loris rescue” by Animal Concerns Research and Education Society (Singapore). ACRES SG YouTube Channel, 28 Apr 2016. URL: (Accessed on 3 Nov 2016).
[i1] Screenshot captured from ACRES: Animal Concerns Research and Education Society (Singapore) Facebook Page. URL: (Accessed on 23 Nov 2016).

Section 5: Identification
[i1] “Bornean slow loris” by Gary Albert.
[i2] Lydekker, R., 1904. On two lorises. Proceedings of the Zoological Society. Volume II. Plate XXIII.
[i3] Schulze, H., Groves, C. P., 2004. Asian lorises: taxonomic problems caused by illegal trade. Pp 33-36 in Nadler, T., Streicher, U., Thang Long, H., editors. Conservation of Primates in Vietnam. Frankfurt: Frankfurt Zoological Society

Section 6: Biology and Ecology
[v1] Video cut from “Foraging behaviour of Bengal Slow Loris” by Bangladesh Slow Loris Research and Conservation. Bangladesh Slow Loris Research and Conservation YouTube Channel, 18 Aug 2016. URL: (Accessed on 21 Nov 2016).
[v2] Video cut from “Social slow loris – The Little Fireface Project” by Little Fireface Project. Little Fireface Project YouTube Channel, 5 Feb 2014. URL: (Accessed on 20 Nov 2016).

Section 7: Taxonomy
[i1] Boddaert, P., 1785. Elenchus animalium.Rotterdam.

Section 8: Phylogeny
[i1] Seiffert, E.R., Simons, E.L., Ryan, T.M. Attia, Y., 2005. Additional remains of Wadilemur elegans, a primitive stem galagid from the late Eocene of Egypt. Proceedings of the National Academy of Sciences. 102(32): 11396–11401.
[i2] Zhang, Y. P., Chen, Z. P. & Shi, L. M., 1993. Phylogeny of the Slow Lorises (Genus Nycticebus): An Approach Using Mitochodrial DNA Restriction Exzyme Analysis. International Journa of Primatology, 14(1): 167–175.
[i3] Somura, H., Hori, H., & Manome, Y., 2012. Sequence analysis of mitochondrial DNAs of 12S rRNA, 16S rRNA, and cytochrome oxidase subunit 1 (COI) regions in slow lorises (Genus Nycticebus) may contribute to improved identification of confiscated specimens. ISRN Zoology.

1. 1 2

Groves, C., 2001. Primate Taxonomy. Smithsonian Institution Press, Washington, DC, USA.

2. 1 2

Nekaris, A. & Streicher, U., 2008. Nycticebus coucang. The IUCN Red List of Threatened Species 2008.

3. 1 2

Fam, S. D., B. P., Y.H.L., & Shekelle, M., 2014. The conservation status of slow lorises Nycticebus spp. in Singapore. Endangered Species Research,25(1), 69-77.

4. 1

Malone, N., Purnama, A.R., Wedana, M. & Fuentes, A., 2002. Assessment of the sale of primates at Indonesian bird markets. Asian Primates, 8: 7−11.

5. 1

Nekaris, K.A.I. & Jaffe, S., 2007. Unexpected diversity of slow lorises (Nycticebus spp.) within the Javan pet trade: im - plications for slow loris taxonomy. Contributions to Zoology, 76(3): 187–196.

6. 1

Ratajszczak, R., 1998. Taxonomy, distribution and status of the lesser slow loris Nycticebus pygmaeus and their implications for captive management. Folia Primatologica, 69: 171−174.

7. 1 2

Nekaris, A. & Streicher, U., 2008. Nycticebus coucang. The IUCN Red List of Threatened Species 2008.

8. 1

Davison, G.W.H., 2008. The red list categories. In: Davison, G.W.H., Ng, P.K.L. & Ho, H.C. (eds) The Singapore red data book:threatened plants and animals of Singapore, 2nd edn. The Nature Society, Singapore, p 1−4

9. 1

Lim K.P.K., Subaraj R., Yeo S.H., Lim N., Lane D. & Lee B.Y.H., 2008. Mammals. In:Davison GWH, Ng PKL, Ho HC (eds) The Singapore red data book: threatened plants and animals of Singapore, 2nd en. The Nature Society, Singapore, p 190−207.

10. 1

Ee, D., 2014. First local loris study slow-going. AsiaOne 20 August 2014. Retrieved from: on 10 November 2016)

11. 1

Basu, R., 2006. Seizures of illegal wildlife at new low. The Straits Times 2 February 2006, p 6.

12. 1

Roonwal, M. & Mohnot, S., 1977. Slow loris. Primates of South Asia: ecology, sociobiology, and behavior. Cambridge, Massachusetts: Harvard University Press.

13. 1 2

Wiens, F., 2002. Behavior and ecology of wild slow lorises (Nycticebus coucang): social organization, infant care system, and diet. University of Bayreuth. Retrieved 1 March 2011.

14. 1 2

Wiens, F. & Zitzmann, A., 2003. Social dependence of infant slow lorises to learn diet. International Journal of Primatology. 24 (5): 1007–1021.

15. 1 2 3

Rowe, N., 1999. The Pictorial Guide to the Living Primates. Pogonias Press, Rhode Island.

16. 1

Boddaert, P., 1785. Elenchus animalium. Rotterdam.

17. 1

Schulze, H., 2004. Lorises and pottos: species, subspecies, local populations. Conservation database for lorises: Vernacular names: English, French, German, others (countries of origin).

18. 1

Wilson, D. E. & Reeder, D. M. (Eds.)., 2005. Mammal species of the world: a taxonomic and geographic reference (Vol. 1). JHU Press.

19. 1

Cheng, Z. P., Zhang, Y. P., Shi, L. M., Liu, R. Q. & Wang, Y. X., 1993. Studies on the chromosomes of genus Nycticebus. Primates, 34: 47–53

20. 1 2

Corbet, G. B. & Hill, J. E., 1980. A World List of Mammalian Species. British Museum (Natural History), London.

21. 1

Ellerman, J. R. & Morrison-Scott, T. C. S., 1951. Checklist of Palaearctic and Indian Mammals 1758–1945. British Museum (Natural History), London.

22. 1

Groves, C. P., 1971. Systematics of the genus Nycticebus. In Biegert, J. & Leutenegger, W. (eds.), Proceeding of the Third International Congress of Primatology, Zurich 1970, Vol. 1: Taxonomy, Anatomy, Reproduction, Karger, Basel. pp. 44–53.

23. 1

Hill, W. C., 1953. Primates: Comparative Anatomy and Taxonomy, I: Strepsirhini, The Edinburgh University Press, Edinburgh.

24. 1

Ma, S. & Wang, Y., 1988. The recent distribution, status and conservation of primates in China. Acta Theriol. Sinica 8: 250–260

25. 1

Petter, J. J. & Petter-Rousseaux, A., 1979. Classification of the prosimians. In Doyle, G. A., and Martin, R. D. (eds.), The Study of Prosimian Behavior, Academic Press, New York, pp. 281–286

26. 1

Geoffroy Saint-Hilaire, Étienne, 1812. Suite au Tableau des Quadrummanes. Seconde Famille. Lemuriens. Strepsirrhini. Annales du Muséum National d'Histoire Naturelle (in French) 19. pp. 156–170.

27. 1

Stone, W. & Rehn, J.A.G., 1902. "A collection of mammals from Sumatra, with a review of genera Nycticebus and Tragulus". Proceedings of the Academy of Natural Sciences of Philadelphia. 54: 127–142.

28. 1

Pocock, R.I., 1939. The fauna of British India, including Ceylon and Burma. Mammalia, vol. 1. London: Taylor and Francis.

29. 1

Nekaris, K.A.I. & Munds, R., 2010. Chapter 22: Using facial markings to unmask diversity: the slow lorises (Primates: Lorisidae: Nycticebus spp.) of Indonesia. In Gursky-Doyen, S.; Supriatna, J. Indonesian Primates. New York: Springer. pp. 383–396.

30. 1

Perelman P., Johnson W.E., Roos C., Seuánez H.N., Horvath J.E. & Moreira M.A.M., 2011. A Molecular Phylogeny of Living Primates. PLoS Genetics, 7(3): e1001342.

31. 1

Seiffert, E.R., Simons, E.L., Ryan, T.M. & Attia, Y., 2005. Additional remains of Wadilemur elegans, a primitive stem galagid from the late Eocene of Egypt. Proceedings of the National Academy of Sciences. 102 (32): 11396–11401.

32. 1 2

Chen, J. H., Pan, D., Groves, C. P., Wang, Y. X., Narushima, E., Fitch-Snyder, H., Crow, P., Thanh, V. N., Ryder, O., Zhang, H. W., Fu, Y. & Zhang, Y., 2006. Molecular phylogeny of Nycticebus inferred from mitochondrial genes. International Journal of Primatology. 27(4): 1187–1200.

33. 1 2

Zhang, Y. P., Chen, Z. P. & Shi, L. M., 1993. Phylogeny of the Slow Lorises (Genus Nycticebus): An Approach Using Mitochondrial DNA Restriction Exzyme Analysis. International Journal of Primatology, 14(1): 167–175.

34. 1

Somura, H., Hori, H., & Manome, Y., 2012. Sequence analysis of mitochondrial DNAs of 12S rRNA, 16S rRNA, and cytochrome oxidase subunit 1 (COI) regions in slow lorises (Genus Nycticebus) may contribute to improved identification of confiscated specimens. ISRN Zoology.

This page was authored by Sim Hui Min

Last curated in 2016

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