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Journal of Threatened Taxa Building evidence for conservaton globally www.threatenedtaxa.org ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) Communication Dusky Langurs Trachypithecus obscurus (Reid, 1837) (Primates: Cercopithecidae) in Singapore: potential origin and conflicts with native primate species Andie Ang, Sabrina Jabbar & Max Khoo 26 June 2020 | Vol. 12 | No. 9 | Pages: 15967–15974 DOI: 10.11609/jot.5818.12.9.15967-15974 For Focus, Scope, Aims, Policies, and Guidelines visit htps://threatenedtaxa.org/index.php/JoTT/about/editorialPolicies#custom-0 For Artcle Submission Guidelines, visit htps://threatenedtaxa.org/index.php/JoTT/about/submissions#onlineSubmissions For Policies against Scientfc Misconduct, visit htps://threatenedtaxa.org/index.php/JoTT/about/editorialPolicies#custom-2 For reprints, contact <[email protected]> The opinions expressed by the authors do not refect the views of the Journal of Threatened Taxa, Wildlife Informaton Liaison Development Society, Zoo Outreach Organizaton, or any of the partners. 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Member Threatened Taxa Journal of Threatened Taxa | www.threatenedtaxa.org | 26 June 2020 | 12(9): 15967–15974 ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) PLATINUM OPEN ACCESS DOI: htps://doi.org/10.11609/jot.5818.12.9.15967-15974 #5818 | Received 27 February 2020 | Final received 08 April 2020 | Finally accepted 25 May 2020 C o m Dusky Langurs Trachypithecus obscurus (Reid, 1837) m u n (Primates: Cercopithecidae) in Singapore: potental origin and i c conficts with natve primate species a t 1 2 3 i Andie Ang , Sabrina Jabbar & Max Khoo o n 1,2 Rafes’ Banded Langur Working Group, Wildlife Reserves Singapore Conservaton Fund, 80 Mandai Lake Road, 729826 Singapore. 3 Wildlife Management Research, Wildlife Management Division, Natonal Parks Board, 50 Dairy Farm Road, 679059 Singapore. 1 [email protected] (corresponding author), 2 [email protected], 3 [email protected] Abstract: The introducton of exotc species can have detrimental efects on local populatons via factors such as resource competton and new threats from disease. Singapore has three natve species of non-human primates: Sunda Slow Loris Nyctcebus coucang, Long- tailed Macaque Macaca fascicularis, and Rafes’ Banded Langur Presbyts femoralis. Over the past few months, several non-natve Dusky Langurs Trachypithecus obscurus were observed in Singapore. We document our observatons, compile reports from social media, and atempt to assess the potental impacts on local primates. Whenever Dusky Langurs were encountered, we recorded the date, tme, GPS coordinates, group demographics, and behaviour, including interactons with natve primates. We also monitored sightng 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 informaton. On 31 August 2019, three Dusky Langurs were seen near a residental 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, indicatng 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. Keywords: Colobine, dispersal, exotc, impacts, macaque. Editor: Susan M. Cheyne, Borneo Nature Foundaton Internatonal, Palangka Raya, Indonesia. Date of publicaton: 26 June 2020 (online & print) Citaton: Ang, A., S. Jabbar & M. Khoo (2020). Dusky Langurs Trachypithecus obscurus (Reid, 1837) (Primates: Cercopithecidae) in Singapore: potental origin and conficts with natve primate species. Journal of Threatened Taxa 12(9): 15967–15974. htps://doi.org/10.11609/jot.5818.12.9.15967-15974 Copyright: © Ang et al. 2020. Creatve Commons Atributon 4.0 Internatonal License. JoTT allows unrestricted use, reproducton, and distributon of this artcle in any medium by providing adequate credit to the author(s) and the source of publicaton. Funding: The frst two authors from the Rafes’ Banded Langur Working Group are funded by Wildlife Reserves Singapore Conservaton Fund. Competng interests: The authors declare no competng interests. Author details: Andie Ang is a research scientst with the Wildlife Reserves Singapore Conservaton Fund, managing a research and conservaton project on the Rafes’ Banded Langurs in Singapore and Malaysia. Sabrina Jabbar is a research assistant with the Wildlife Reserves Singapore Conservaton Fund, working on the conservaton of Rafes’ Banded Langurs. Max Khoo is with the Wildlife Management Research team in the Natonal Parks Board, Singapore, and works on various terrestrial ecology research projects. Author contributon: All authors contributed equally to the study design, feld work, data analysis and writng of artcle. Acknowledgements: We thank Bryan Lim, Chanelle Lim, Ian Siah, Cindy Yeo, and Peter Chua for providing sightng informaton of Dusky Langurs. We also thank citzen scientsts Uriana Argeros, Alice Early, Steve Early, and Katherine Kim for alertng authors to the sightng of Rafes’ Banded Langurs in Thomson Nature Park. The frst two authors from the Rafes’ Banded Langur Working Group are funded by Wildlife Reserves Singapore Conservaton Fund. 15967 J TT Non-natve Dusky Langurs in Singapore Ang et al. INTRODUCTION and atempt to assess the potental impacts of Dusky Langurs on local primates. Singapore is home to three species of non-human primates—Sunda Slow Loris Nyctcebus coucang, Long- tailed Macaque Macaca fascicularis fascicularis, and MATERIALS AND METHODS Rafes’ Banded Langur Presbyts femoralis. While the populaton size of the Sunda Slow Loris in Singapore At 10.30h on 31 August 2019, staf of the Natonal is unknown, it is considered natonally Critcally Parks Board (NParks) of Singapore were informed by a Endangered (Lim et al. 2008) and globally Vulnerable member of public that a group of Dusky Langurs was (Nekaris & Streicher 2008). The Long-tailed Macaque seen at 891B Woodlands Drive 50 in the northern part of populaton has an estmated 1,800–2,200 individuals Singapore. NParks staf, including the last author, went (Riley et al. 2015) and is not facing immediate threats to the locaton at 12.35h to observe the Dusky Langurs to survival (Ong & Richardson 2008). The Rafes’ untl 19.15h that evening. The next day NParks received Banded Langur is natonally Critcally Endangered (Lim further informaton about the locaton of what was et al. 2008) and is also considered Critcally Endangered presumably the same group of langurs from members globally given its small populaton size (60 individuals in of the public. Singapore and 250­­­­­–300 individuals in Malaysia), and a On 30 December 2019, we were alerted to a recent recommendaton to elevate it from subspecies to photograph of Dusky Langurs in Singapore which was species (Ang et al. 2020). posted in a Facebook group (Nature Society Singapore). In additon to these primate species, sightngs of In order not to alarm the public regarding the presence others have been reported in Singapore over the years. of a non-natve primate species before verifying the Some sightngs were atributable to pet abandonment sightng, we did not publicly seek for observatons or illegal ownership of primate pets. For example in on social media platorms. Instead, we monitored 2004 an African Vervet Monkey Chlorocebus pygerythrus sightng reports of Dusky Langurs posted on local major was repatriated to Zambia afer being kept as a pet Facebook groups (Birds, Insects and Creatures of Asia; in Singapore (ACRES 2004), and in 2018, fve South Nature Society Singapore; Wildlife of MacRitchie & American marmosets were found abandoned in public Central Catchment) from 30 December 2019 to 31 areas in Singapore (Channel NewsAsia 2018). Other January 2020, and privately messaged the person(s) for sightngs may have been arrivals from nearby areas. more informaton. On 19 February 2008, a single adult Dusky Langur As part of an ongoing research project on Rafes’ Trachypithecus obscurus obscurus was observed at Banded Langurs in Singapore, we conducted feld Kent Ridge forest in southern part of Singapore, but its observatons on weekdays and weekends within the origin and subsequent fate were unknown (Yeo & Lim Central Nature Reserve. Whenever Dusky Langurs 2013). In 2015, a Southern Pig-tailed Macaque Macaca were encountered, we recorded the date, tme, nemestrina was rescued from a car workshop and later GPS coordinates, group demographics (number of rehomed in Malaysia (AsiaOne 2015). individuals, sex, and age group), and behaviour,