Main Article Content
The introduction of exotic species can have detrimental effects on local populations via factors such as resource competition and new threats from disease. Singapore has three native species of non-human primates: Sunda Slow Loris Nycticebus coucang, Long-tailed Macaque Macaca fascicularis, and Raffles’ Banded Langur Presbytis femoralis. Over the past few months, several non-native Dusky Langurs Trachypithecus obscurus were observed in Singapore. We document our observations, compile reports from social media, and attempt to assess the potential impacts on local primates. Whenever Dusky Langurs were encountered, we recorded the date, time, GPS coordinates, group demographics, and behaviour, including interactions with native primates. We also monitored sighting reports of Dusky Langurs posted on local major Facebook groups from 30 December 2019 to 31 January 2020, and privately messaged the person(s) for more information. On 31 August 2019, three Dusky Langurs were seen near a residential area in the northern part of Singapore, and two to three individuals were reported on 14 subsequent occasions. During one encounter on 18 January 2020, an adult male Long-tailed Macaque chased a group of Dusky Langurs from a feeding tree. The next day the same group of Dusky Langurs chased a group of 11 Banded Langurs from another feeding tree. The Dusky Langurs appeared to be healthy and wild, indicating that they may have swum across the Johor Strait and/or traveled on the Johor-Singapore Causeway from Malaysia. Further monitoring of these Dusky Langurs will be required to assess their impact on local primates.
Authors own the copyright to the articles published in JoTT. This is indicated explicitly in each publication. The authors grant permission to the publisher Wildlife Information Liaison Development (WILD) Society to publish the article in the Journal of Threatened Taxa. The authors recognize WILD as the original publisher, and to sell hard copies of the Journal and article to any buyer. JoTT is registered under the Creative Commons Attribution 4.0 International License (CC BY), which allows authors to retain copyright ownership. Under this license the authors allow anyone to download, cite, use the data, modify, reprint, copy and distribute provided the authors and source of publication are credited through appropriate citations (e.g., Son et al. (2016). Bats (Mammalia: Chiroptera) of the southeastern Truong Son Mountains, Quang Ngai Province, Vietnam. Journal of Threatened Taxa 8(7): 8953–8969. https://doi.org/10.11609/jott.2722.214.171.12453-8969). Users of the data do not require specific permission from the authors or the publisher.
ACRES (2004). First ever repatriation of a confiscated pet primate. http://acres.org.sg/core/wp-content/uploads/2015/05/4_may_04_first_ever_repatriation_of_a_confiscated_pet_primate.pdf Accessed 2 February 2020.
Ang, A. & N. Baker (2019). Raffles’ banded langur Presbytis femoralis femoralis in southern Pahang, Peninsular Malaysia. Southeast Asia Vertebrate Records 2019: 52–53.
Ang, A., D.I. Roesma, V. Nijman, R. Meier, A. Srivathsan & Rizaldi (2019). Faecal DNA to the rescue: Shotgun sequencing of non-invasive samples reveals two subspecies of Southeast Asian primates to be Critically Endangered species. Scientific Reports 10: 9396. https://doi.org/10.1038/s41598-020-66007-8 DOI: https://doi.org/10.1038/s41598-020-66007-8
AsiaOne (2015). Endangered Pig-tailed Macaque rehomed in Malaysia. AsiaOne, 24 August 2015. https://www.asiaone.com/singapore/endangered-pig-tailed-macaque-rehomed-malaysia Accessed 2 February 2020.
Channel NewsAsia (2018). Wildlife group rescues abandoned marmoset seen ‘appearing lost’ at Punggol HDB. Channel NewsAsia, 17 December 2018. https://www.channelnewsasia.com/news/singapore/abandoned-monkey-marmoset-punggol-lost-rescued-acres-11039274 Accessed 2 February 2020.
Chew, H.M. (2016). Rare sighting of endangered Malayan tapir at Changi. The Straits Times, 25 June 2016. https://www.straitstimes.com/singapore/rare-sighting-of-endangered-malayan-tapir-at-changi Accessed 2 February 2020.
Gabbatiss, J. (2017). The strange experiments that revealed most mammals can swim. BBC Earth, 21 March 2017. http://www.bbc.com/earth/story/20170320-the-cruel-experiments-that-revealed-most-mammals-can-swim Accessed 8 April 2020.
Hatcher, M.J., J.T.A. Dick & A.M. Dunn (2012). Disease emergence and invasions. Functional Ecology 26: 1275–1287. https://doi.org/10.1111/j.1365-2435.2012.02031.x DOI: https://doi.org/10.1111/j.1365-2435.2012.02031.x
IUCN (2018). Guidelines for invasive species planning and management on islands. Cambridge, UK and Gland, Switzerland, 40pp.
IUCN SSC (2013). Guidelines for reintroduction and other conservation translocations. Version 1.0. Gland, Switzerland, 57pp.
Lim, K.K.P., R. Subaraj, S.H. Yeo, N. Lim, D. Lane & B.Y.H. Lee (2008). Mammals, pp.190–207. In: Davison, G.W.H., P.K.L. Ng & H.C. Ho (eds.). The Singapore Red Data Book. Threatened Plants & Animals of Singapore. 2nd Edition. The Nature Society (Singapore), Singapore, 285pp.
Liu, Z., B. Wang, T. Nadler, G. Liu, T. Sun, C. Huang, Q. Zhou, J. Zhou, T. Que, Z. Wang & C. Roos (2013). Relatively recent evolution of pelage coloration in Colobinae: phylogeny and phylogeography of three closely related langur species. PLoS One 8(4): e61659. https://doi.org/10.1371/journal.pone.0061659 DOI: https://doi.org/10.1371/journal.pone.0061659
Nekaris, A. & U. Streicher (2008). Nycticebus coucang. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. Downloaded on 1 February 2020.
Oliveira, L.C. & C.E.V. Grelle (2012). Introduced primate species of an Atlantic Forest region in Brazil: present and future implications for the native fauna. Tropical Conservation Science 5(1): 112–120. https://doi.org/10.1177/194008291200500110 DOI: https://doi.org/10.1177/194008291200500110
Ong, P. & M. Richardson (2008). Macaca fascicularis fascicularis. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. Downloaded on 1 February 2020.
Peeler, E.J., B.C. Oidtmann, P.J. Midtlyng, L. Miossec & R.E. Gozlan (2011). Non-native aquatic animals introductions have driven disease emergence in Europe. Biological Invasions 13(6): 1291–1303. https://doi.org/10.1007/s10530-010-9890-9 DOI: https://doi.org/10.1007/s10530-010-9890-9
Raffles, S.T. (1821). Descriptive catalogue of a zoological collection made in the island of Sumatra and its vicinity. Transactions of the Linnean Society of London 13: 246.
Riley, C.M., S.L. Jayasri & M.D. Gumert (2015). Results of a nationwide census of the long-tailed macaque (Macaca fascicularis) population of Singapore. Raffles Bulletin of Zoology 63: 503–515.
Roos, C., D. Zinner, L.S. Kubatko, C. Schwarz, M. Yang, D. Meyer, S.D. Nash, J. Xing, A.M. Batzer, M. Brameier, F.H. Leendertz, T. Ziegler, D. Perwitasari-Farajallah, T. Nadler, L. Walter & M. Osterholz (2011). Nuclear versus mitochondrial DNA: evidence for hybridization in colobine monkeys. BMC Evolutionary Biology 11(1): 77. https://doi.org/10.1186/1471-2148-11-77 DOI: https://doi.org/10.1186/1471-2148-11-77
Roos, C., R. Boonratana, J. Supriatna, J.R. Fellowes, C.P. Groves, S.D. Nash, A.B. Rylands & R.A. Mittermeier (2014). An updated taxonomy and conservation status review of Asian primates. Asian Primates Journal 4(1): 2–38.
Ruslin, F., I. Matsuda & B.M. Md-Zain (2019). The feeding ecology and dietary overlap in two sympatric primate species, the Long-tailed Macaque (Macaca fascicularis) and Dusky Langur (Trachypithecus obscurus obscurus), in Malaysia. Primates 60(1): 41–50. https://doi.org/10.1007/s10329-018-00705-w DOI: https://doi.org/10.1007/s10329-018-00705-w
Sha, J.C.M. & G. Hanya (2013). Diet, activity, habitat use, and ranging of two neighboring groups of food‐enhanced long‐tailed macaques (Macaca fascicularis). American Journal of Primatology 75(6): 581–592. https://doi.org/10.1002/ajp.22137 DOI: https://doi.org/10.1002/ajp.22137
The Straits Times (2019). Celebs and influencers in Malaysia sharing shots of exotic pets, fueling concern for illegal wildlife trade. The Straits Times, 22 July 2019. https://www.straitstimes.com/asia/se-asia/celebs-and-influencers-in-malaysia-sharing-shots-of-exotic-pets-fuelling-concern-of Assessed 3 February 2020.
Yeo, H.H.T. & K.K.P. Lim (2013). Dusky langur at Kent Ridge. Singapore Biodiversity Records 2013: 125.
Zainol, N., A.N. Roshidi, S.M. Husin, A. Md-Shukor, R. Ilias & S. Md-Nor (2019). Impact of forest isolation on mammals diversity and distribution due to impoundment of Hulu Terengganu hydroelectric project, Terengganu, Peninsular Malaysia. International Conference on Dam Safety Management and Engineering 2019: 468–478.
Zinner, D., M.L. Arnold & C. Roos (2011). The strange blood: natural hybridization in primates. Evolutionary Anthropology: Issues, News, and Reviews 20(3): 96–103. https://doi.org/10.1002/evan.20301 DOI: https://doi.org/10.1002/evan.20301