pp 1–12 | Cite as

Population abundance and distribution of the endangered golden langur (Trachypithecus geei, Khajuria 1956) in Bhutan

  • Phuntsho ThinleyEmail author
  • Tshewang Norbu
  • Rajanathan Rajaratnam
  • Karl Vernes
  • Kezang Wangchuk
  • Karma Choki
  • Jigme Tenzin
  • Sangay Tenzin
  • Kinley
  • Shacha Dorji
  • Tshering Wangchuk
  • Karma Cheda
  • Gempa
Original Article


Reliable population estimates are lacking for many South Asian primate species, including the golden langur (Trachypithecus geei), which is endangered and restricted to Bhutan and northeast India. Although well studied in India, few studies exist on this species in Bhutan. In November 2017, we undertook a nationwide survey of golden langurs in Bhutan using double observers along trail-based transects in 17 blocks within its habitat, and modeled its distribution using MaxEnt. A total of 2439 golden langurs in 222 groups were collectively encountered by 17 teams of double observers, from which, an overall population of 2516 ± SE 363 individuals and 236 ± SE 9 groups were estimated. Group sizes varied from 2 to 35 individuals with a mean of 11 ± SD 0.38 individuals. A total of 468 adult males (19%), 924 adult females (38%), 649 juveniles (27%), and 398 infants (16%) were counted. Adult male-to-female sex ratio was 1:1.97 and adult female-to-infant ratio was 1:0.43. We determined 2848 km2 of suitable area for golden langurs in Bhutan and estimated a density of 0.88 individuals/km2. Our population estimate of golden langurs in Bhutan is much lower than the current IUCN estimate of 4000 individuals for Bhutan, necessitating a reassessment of its current conservation status due to threats from road kills, electrocution, and development activities like road construction, hydropower, and electrical transmission lines. We further recommend our refined double-observer survey method to reliably estimate primate populations in rugged terrain.


Bhutan Endangered Endemic Eastern Himalayas Golden langur 



We thank the Royal Government of Bhutan for administrative approval and funding for the study and the Mangdechhu Hydropower Project Authority for supplemental funding. We acknowledge field efforts and diligence of other observers nominated from Tsirang Division (Cheten Dorji), Sarpang Division (R. B. Mongar, Sangay Dorji, and Rinzin Wangchuk), Zhemgang Division (Kezang Dorji and Tshering Dorji), Bumthang Division (Sonam Rinzin and Dorji Thinley), Jigme Singye Wangchuck National Park (Namgay Dorji, Cheku, Tshering, Sanjit Kumar Rai, Kado Rinchen, and Pema Namgyel), Royal Manas National Park (Chhimi Tshewang, Tshering Tashi, Jamphel Lhendup, Sangay Tenzin, Dambar Bahadur Chhetri, Deo Kumar Gurung, Ngawang Namgyal, and Sonam Dorji), and Phibsoo Wildlife Sanctuary (Tendel Wangdi, Karma Chedup, Tshewang Tenzin, and Tshering Wangdi). We thank Phento Tshering, the former Director of the Department of Forests and Park Services and Shacha Dorji, Director of the Ugyen Wangchuck Institute for Conservation and Environment Research, for administrative approval and the Chief Forestry Officers (Dimple Thapa, Pankey Dukpa, Phub Dhendup, Singye Wangmo, Dorji Rabten, Kinzang Gyeltshen, and Tashi Dendup), Program Director (Kaka Tshering), and the Range Officers of JSWNP (Phuntshok and Yeshey Wangdi) for their critical support and cooperation during the surveys and preliminary visits.


Funding received from Royal Government of Bhutan (FY 2017–2018) and Mangdechhu Hydropower Project Authority (FY 2017–2018).


  1. Afendi N, Rachmawan D, Gumert MD (2011) The long-tailed macaques of Karimunjawa (Macaca fascicularis karimondjiwae): a small and isolated subspecies threatened by human-macaque conflict. In: Gumert MDFA, Jones-Engel L (eds) Monkeys on the edge: ecology and management of long-tailed macaques and their interface with humans. Cambridge University Press, Cambridge, pp 12–14Google Scholar
  2. Anderson DR, Laake JL, Crain BR, Burnham KP (1979) Guidelines for line transect sampling of biological populations. J Wildl Manag 43:70–78CrossRefGoogle Scholar
  3. Aquino R, Zárate R, López L, García G, Charpentier E (2015) Current status and threats to Lagothrix flavicauda and other primates in montane forest of the Región Huánuco. Primate Conserv 2015:31–42CrossRefGoogle Scholar
  4. Aquino R, López L, Falcón R, Dìaz S, Gálvez H (2019) First inventory of primates in the montane forests of the Pasco and Ucayali Regions, Peruvian Amazon. Primate Conserv 33:11Google Scholar
  5. Buckland ST, Plumptre AJ, Thomas L, Rexstad EA (2010) Design and analysis of line transect surveys for primates. Int J Primatol 31:833–847CrossRefGoogle Scholar
  6. Bukie J, Ebu V, Nchor A (2015) Population ecology of the white-throated monkey (Cercopithecus erythrogaster) in Afi Mountain Wildlife Sanctuary (AMWS), Cross River State. Niger Int J Agric For 5:245–248Google Scholar
  7. Burnham K, Anderson D (1976) Mathematical models for nonparametric inferences from line transect data. Biometrics 32:325–336CrossRefGoogle Scholar
  8. Burnham KP, Anderson DR, Laake JL (1980) Estimation of density from line transect sampling of biological populations. Wildl Monogr 72:3–202Google Scholar
  9. Chetry D, Chetry R, Ghosh K, Bhattacharjee P (2010) Status and conservation of golden langur in Chakrashila Wildlife Sanctuary, Assam, India. Primate Conserv 25:81–86. CrossRefGoogle Scholar
  10. Chetry R, Chetry D, Bhattacharjee P (2017) Golden langur: Trachypithecus geei Khajuria, 1956, India and Bhutan, 2016. In: Schwitzer C et al (eds) Primates in peril: the world’s 25 most endangered primates 2016–2018. IUCN SSC Primate Specialist Group (PSG), International Primatological Society (IPS), Conservation International (CI), Bristol Zoological Society (BZS), Arlington, pp 55–58Google Scholar
  11. Choudhury A (1992) Golden langur—distribution confusion. Oryx 26:172–173CrossRefGoogle Scholar
  12. Choudhury A (2002) Golden langur Trachypithecus geei threatened by habitat fragmentation. Zoo’s Print J 17:699–703CrossRefGoogle Scholar
  13. Choudhury A (2008) Primates of Bhutan and observations of hybrid langurs. Primate Conserv 23:65–73. CrossRefGoogle Scholar
  14. Das J, Medhi R, Molur S (2008) Trachypithecus geei. The IUCN Red List of Threatened Species 2008: e.T22037A9348940. Downloaded on 21 Jan 2019
  15. Davenport TR, De Luca DW, Jones T, Mpunga NE, Machaga SJ, Kitegile A, Phillipps GP (2008) The critically endangered kipunji Rungwecebus kipunji of southern Tanzania: first census and conservation status assessment. Oryx 42:352–359CrossRefGoogle Scholar
  16. Davenport TR, Fakih SA, Kimiti SP, Kleine LU, Foley LS, De Luca DW (2019) Zanzibar’s endemic red colobus Piliocolobus kirkii: first systematic and total assessment of population, demography and distribution. Oryx 53:1–9. CrossRefGoogle Scholar
  17. de Luna AG, Link A (2018) Distribution, population density and conservation of the critically endangered brown spider monkey (Ateles hybridus) and other primates of the inter-Andean forests of Colombia. Biodivers Conserv 27:3469–3511CrossRefGoogle Scholar
  18. Dorji S, Rajaratnam R, Vernes K (2012) The vulnerable red panda Ailurus fulgens in Bhutan: distribution, conservation status and management recommendations. Oryx 46:536–543CrossRefGoogle Scholar
  19. Elith J, Phillips SJ, Hastie T, Dudı´k M, En Chee Y, Yates C (2010) A statistical explanation of MaxEnt for ecologists. Divers Distrib 17:43–57. CrossRefGoogle Scholar
  20. Estrada A, Garber PA, Mittermeier RA et al (2018) Primates in peril: the significance of Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo for global primate conservation. PeerJ 6:e4869. CrossRefGoogle Scholar
  21. Fashing PJ, Cords M (2000) Diurnal primate densities and biomass in the Kakamega Forest: an evaluation of census methods and a comparison with other forests. Am J Primatol 50:139–152CrossRefGoogle Scholar
  22. Fielding AH, Bell JF (1997) A review of methods for the assessment of prediction errors in conservation presence/absence models. Environ Conserv 24:38–49CrossRefGoogle Scholar
  23. Forsyth DM, Hickling GJ (1997) An improved technique for indexing abundance of Himalayan thar. N Z J Ecol 21:97–101Google Scholar
  24. Gumert MD, Hamada Y, Malaivijitnond S (2013) Human activity negatively affects stone tool-using Burmese long-tailed macaques Macaca fascicularis aurea in Laem Son National Park, Thailand. Oryx 47:535–543CrossRefGoogle Scholar
  25. Horwich RH, Das R, Bose A (2013) Conservation and the current status of the golden langur in Assam, India, with reference to Bhutan. Primate Conserv 27:77–83. CrossRefGoogle Scholar
  26. Jarvis A, Reuter HI, Nelson A, Guevara E (2006) International Centre for Tropical Agriculture (CIAT). Accessed 12 Apr 2016
  27. Khajuria H (1981) The golden langur (Presbytis Geei Khajuria). Zoologiana 4:39–43Google Scholar
  28. Khanal L, Chalise MK, Jiang X (2018) Ecological niche modelling of Himalayan langur (Semnopithecus entellus) in southern flank of the Himalaya. J Inst Sci Technol 23:1–9CrossRefGoogle Scholar
  29. Khanal L, Chalise MK, Jiang X (2019) Distribution of the threatened Assamese Macaque Macaca assamensis (Mammalia: Primates: Cercopithecidae) population in Nepal. J Threat Taxa 11:13047–13057CrossRefGoogle Scholar
  30. Kumara HN, Radhakrishna S (2013) Evaluation of census techniques to estimate the density of slender Loris (Loris lydekkerianus) in southern India. Curr Sci India 104:1083–1086Google Scholar
  31. Leki Thinley P, Rajaratnam R, Shrestha R (2018) Establishing baseline estimates of blue sheep (Pseudois nayaur) abundance and density to sustain populations of the vulnerable snow leopard (Panthera uncia) in Western Bhutan. Wildl Res 45:38–46. CrossRefGoogle Scholar
  32. Li Y-C, Liu F, He XY et al (2015) Social organization of Shortridge’s capped langur (Trachypithecus shortridgei) at the Dulongjiang Valley in Yunnan. China Zool Res 36:152–160Google Scholar
  33. Ma C, Luo Z, Liu C, Orkin JD, Xiao W, Fan P (2015) Population and conservation status of Indochinese gray langurs (Trachypithecus crepusculus) in the Wuliang Mountains, Jingdong, Yunnan, China. Int J Primatol 36:749–763CrossRefGoogle Scholar
  34. Marshall AR, Lovett JC, White PC (2008) Selection of line-transect methods for estimating the density of group-living animals: lessons from the primates. Am J Primatol 70:452–462CrossRefGoogle Scholar
  35. Matsuda I, Otani Y, Bernard H, Wong A, Tuuga A (2016) Primate survey in a Bornean flooded forest: evaluation of best approach and best timing. Mamm Study 41:101–106. CrossRefGoogle Scholar
  36. NSSC, PPD (2011) Bhutan Land Cover Assessment 2010. National Soil Service Centre, Department of Agriculture, MoAF, Thimphu, BhutanGoogle Scholar
  37. OCC (Office of the Census Commissioner) (2005) Population and housing census of Bhutan 2005. National Statistics Bureau, Thimphu, BhutanGoogle Scholar
  38. Ohsawa M (1987) Life zone ecology of the Bhutan Himalaya. Laboratory of Ecology, Chiba University, Chiba, JapanGoogle Scholar
  39. Peres CA (1999) General guidelines for standardizing line-transect surveys of tropical forest primates. Neotrop Primates 7:11–16Google Scholar
  40. Petros I, Mekonen S, Gena H, Mesfin Y (2018) Population status, distribution, and threats of Colobus guereza gallarum in Bale Mountains National Park, Southeastern Ethiopia. Int J Nat Resour Ecol Manag 3:39Google Scholar
  41. Phillips SJ, Anderson RP, Schapire RE (2006) Maximum entropy modeling of species geographic distributions. Ecol Model 190:231–259. CrossRefGoogle Scholar
  42. Plumptre AJ, Cox D (2006) Counting primates for conservation: primate surveys in Uganda. Primates 47:65–73CrossRefGoogle Scholar
  43. Puig-Lagunes ÁA, Canales-Espinosa D, Rangel-Negrín A, Dias PAD (2016) The influence of spatial attributes on fragment occupancy and population structure in the Mexican mantled howler (Alouatta palliata mexicana). Int J Primatol 37:656–670CrossRefGoogle Scholar
  44. Riley CM, Jayasri SL, Gumert MD (2015) Results of a nationwide census of the long-tailed macaque (Macaca fascicularis) population of Singapore. Raffles B Zool 63:503–515Google Scholar
  45. Roy D, Nagarajan R (2018) Biology, ecology, and conservation of golden langur, Trachypithecus geei. In: Sivaperuman C, Venkataraman K (eds) Indian hotspots. Springer, Singapore, pp 251–283CrossRefGoogle Scholar
  46. Rylands AB, Williamson EA, Hoffmann M, Mittermeier RA (2008) Primate surveys and conservation assessments. Oryx 42:313–314CrossRefGoogle Scholar
  47. Sangay T, Rajaratnam R, Vernes K (2016) Current distribution and conservation status of Bhutan Takin Budorcas whitei Lydekker, 1907 (Artiodactyla: Bovidae). J Threat Taxa 8:9630–9637CrossRefGoogle Scholar
  48. Shahnawaz, Strobl J (2015) A zonal analysis of the climatic conditions in Bhutan. In: Shahnawaz, Thinley U (eds) Climate change, environment and development in Bhutan, Thimphu, Bhutan, 2015. Centre for Rural Development, College of Natural Resources, Royal University of Bhutan, pp 1–22Google Scholar
  49. Spaan D, Ramos-Fernández G, Schaffner CM, Pinacho-Guendulain B, Aureli F (2017) How survey design affects monkey counts: a case study on individually recognized spider monkeys (Ateles geoffroyi). Folia Primatol 88:409–420. CrossRefGoogle Scholar
  50. Spaan D, Ramos-Fernández G, Schaffner CM, Smith-Aguilar SE, Pinacho-Guendulain B, Aureli F (2019) Standardizing methods to estimate population density: an example based on habituated and unhabituated spider monkeys. Biodivers Conserv 28:847–862CrossRefGoogle Scholar
  51. Srivastava A (2006) Ecology and conservation of the golden langur, Trachypithecus geei, in Assam, India. Primate Conserv 21:163–170. CrossRefGoogle Scholar
  52. Srivastava A, Biswas J, Das J, Bujarbarua P (2001) Status and distribution of golden langurs (Trachypithecus geei) in Assam, India. Am J Primatol 55:15–23CrossRefGoogle Scholar
  53. Subba P (1989) The status and conservation of the golden langurs in the Manas National Park. Tiger Pap 16:16–18Google Scholar
  54. Suryawanshi KR, Bhatnagar YV, Mishra C (2012) Standardizing the double-observer survey method for estimating mountain ungulate prey of the endangered snow leopard. Oecologia 169:581–590. CrossRefGoogle Scholar
  55. Thinley P, Rajaratnam R, Tighe M, Vernes K, Norbu T, Dorji R, Tenzin S (2019) Understanding primate‐human interaction: Socioeconomic correlates of local awareness and attitude toward the endangered golden langur Trachypithecus geei (Khajuria, 1956) in Bhutan. Am J Primatol 81:e22995. CrossRefGoogle Scholar
  56. Wangchuk T (1995) A census and the biogeography of golden langur (Presbytis geei) in Bhutan. Tiger Pap 22:1–6Google Scholar
  57. Wangchuk T (2005) The evolution, phylogeography, and conservation of the golden langur (Trachypithecus geei) in Bhutan. Doctoral dissertation, University of MarylandGoogle Scholar
  58. Wangchuk T, Inouye DW, Hare MP (2003) A new subspecies of golden langur (Trachypithecus geei) from Bhutan. Folia Primatol 74:104–108. CrossRefGoogle Scholar
  59. Wangchuk T, Thinley P, Tshering K, Tshering C, Yonten D, Pema B, Wangchuk S (2004) A field guide to the mammals of Bhutan. Royal Government of Bhutan, Thimphu, BhutanGoogle Scholar
  60. Wangchuk T, Inouye DW, Hare MP (2008) The emergence of an endangered species: evolution and phylogeny of the Trachypithecus geei of Bhutan. Int J Primatol 29:565–582. CrossRefGoogle Scholar

Copyright information

© Japan Monkey Centre and Springer Japan KK, part of Springer Nature 2019

Authors and Affiliations

  • Phuntsho Thinley
    • 1
    • 3
    Email author
  • Tshewang Norbu
    • 1
  • Rajanathan Rajaratnam
    • 2
  • Karl Vernes
    • 3
  • Kezang Wangchuk
    • 1
  • Karma Choki
    • 4
  • Jigme Tenzin
    • 4
  • Sangay Tenzin
    • 4
  • Kinley
    • 5
  • Shacha Dorji
    • 5
  • Tshering Wangchuk
    • 5
  • Karma Cheda
    • 5
  • Gempa
    • 5
  1. 1.Ugyen Wangchuck Institute for Conservation and Environment Research, Department of Forests and Park ServicesLamaigoenpaBhutan
  2. 2.Geography and Planning, University of New EnglandArmidaleAustralia
  3. 3.Ecosystem Management, University of New EnglandArmidaleAustralia
  4. 4.Sarpang Forest Division, Department of Forests and Park ServicesSarpangBhutan
  5. 5.Tsirang Forest Division, Department of Forests and Park ServicesTsirangBhutan

Personalised recommendations