Modeling Potential Distribution of the Black-shanked Douc (Pygathrix nigripes)
Main Article Content
Abstract
The Black-shanked douc - Pygathrix nigripes (P. nigripes) is an endangered primate found only in a small region between Vietnam and Cambodia. In recent decades, the species populations have been significantly reduced in their common strongholds because of the pressure from illegal hunting and habitat destruction. The actual distribution of this species remains poorly understood. To better understand the distribution patterns of this endangered primate, we collate localities from previous studies and our field surveys to model the douc’s potential distribution using MaxEnt, a widely used species distribution modeling method. The model results show that, the main distribution range of P. nigripes covers the region of Dak Lak, Khanh Hoa, Lam Dong, and Dong Nai provinces, with an area of approximately 62,000 km2. Based on the optimal model, we recommend future field surveys in several potential areas to identify unknown populations of the douc. We also suggest possible natural barriers of the Black-shanked douc and its relatives, and its implications for conservation activities.
References
[2] D. Hoang, Q. Le, B. Rawson, J. O’Brien, H. Covert, Pygathrix nigripes, The IUCN Red List of Threatened Species, International Union for Conservation of Nature, Gland, 2021.
[3] Vietnam Academy of Science and Technology, Vietnam Red Data Book – Part 1: Animals, Publishing House of Science and Technology, Hanoi, 2024 (in Vietnamese).
[4] N. H. Ha, V. M. Dam, T. V. Dung, The Population Status of the Black-Shanked Douc Langurs (Pygathrix nigripes) in Chua Chan Mountain, Dong Nai Province, Vietnam, Vietnamese Journal of Primatology, Vol. 3, 2023, pp. 69-78.
[5] A. T. Nguyen, M. Le, Modeling‐Facilitated Field Survey Discovers of a New Population of the Annamite Striped Rabbit in Kon Tum Province, Vietnam, Ecology and Evolution, Vol. 14, 2024, pp. 1-8, https://doi.org/10.1002/ece3.70752.
[6] M. Schingen, C. Pham, T. Le, M. Bonkowski, T. Ziegler, Discovery of a New Crocodile Lizard Population in Vietnam: Population Trends, Future Prognoses and Identification of Key Habitats for Conservation, Revue Suisse de Zoologie, Vol. 123, 2016, pp. 241-251, https://doi.org/10.5281/zenodo.155297.
[7] T. A. Nguyen, C. T. H. Nhung, P. J. Galante, M. Le, Rapid Decline and Fragmentation of the Distribution of an Enigmatic Small Carnivore, the Owston’s Civet, in Response to Future Climate Change, Frontiers of Biogeography, Vol. 14, 2022, pp. 1-12, https://doi.org/10.21425/F5FBG53201.
[8] N. N. Bett, M. E. Blair, E. J. Sterling, Ecological Niche Conservatism in Doucs (Genus Pygathrix), International Journal of Primatology, Vol. 33, 2012, pp. 972-988, https://doi.org/10.1007/s10764-012-9622-3.
[9] M. E. Blair, T. A. Nguyen, M. D. Le, Z. Liu, T. Meng, N. Horning, E. J. Sterling, H. M. Thach, M. Xu, P. J. Galante, Karst as an Abiotic Driver of François’ Langur Distribution, with Predictions for Biological Communities on Karst under Climate Change, Frontiers of Biogeography, Vol. 14, 2022, pp. 1-13, https://doi.org/10.21425/F5FBG51838.
[10] N. U. Cardona, M. Blair, M. Londoño, R. Loyola, J. V. Tibatá, H. M. Devia, Species Distribution Modeling in Latin America: A 25-Year Retrospective Review, Tropical Conservation Science, Vol. 12, 2019, pp. 1-19, https://doi.org/10.1177/1940082919854058.
[11] R. G. Pearson, C. J. Raxworthy, M. Nakamura, A. T. Peterson, Predicting Species Distributions from Small Numbers of Occurrence Records: A Test Case Using Cryptic Geckos in Madagascar, Journal of Biogeography, Vol. 34, 2007, pp. 102-117, https://doi.org/10.1111/j.1365-2699.2006.01594.x.
[12] S. Phillips, R. Anderson, M. Dudík, R. Schapire, M. Blair, Opening the Black Box: An Open-Source Release of Maxent, Ecography, Vol. 40, 2017,
pp. 887-893, https://doi.org/10.1111/ecog.03049.
[13] T. Nadler, F. Momberg, N. X. Dang, N. Lormee, Vietnam Primate Conservation Status Review 2002-Part 2: Leaf Monkeys, Fauna & Flora International, Vietnam Programme and Frankfurt Zoological Society, Hanoi, 2003.
[14] H. R. Sofaer, C. S. Jarnevich, I. S. Pearse, R. L. Smyth, S. Auer, G. L. Cook, T. C. Edwards, G. F. Guala, T. G. Howard, J. T. Morisette, H. Hamilton, Development and Delivery of Species Distribution Models to Inform Decision-Making, Bioscience, Vol. 69, 2019, pp. 544-557, https://doi.org/10.1093/biosci/biz045.
[15] M. Blair, M. Le, M. Xu, Species Distribution Modeling to Inform Transboundary Species Conservation and Management under Climate Change: Promise and Pitfalls, Frontiers of Biogeography, Vol. 14, 2022, pp. 1-11, https://doi.org/10.21425/F5FBG54662.
[16] A. T. Nguyen, H. T. Dinh, M. Le, N. Ha, Status of a Second Viable Population of the Critically Endangered Delacour’s Langur in Viet Nam, Oryx, Vol. 56, 2022, pp. 439-441, https://doi.org/10.1017/S0030605321000326.
[17] T. V. Nguyen, H. Man, A. Nguyen, An Assessment of Potential Distribution and Climate Change Impacts on a Critically Endangered Primate, the Delacour’s Langur, The Raffles Bulletin of Zoology, Vol. 70, 2022, pp. 30-38, https://doi.org/10.26107/RBZ-2022-0003.
[18] M. E. A. Lammens, R. A. Boria, A. Radosavljevic, B. Vilela, R. P. Anderson, spThin: An R Package for Spatial Thinning of Species Occurrence Records for Use in Ecological Niche Models, Ecography, Vol. 38, 2015, pp. 541-545, https://doi.org/10.1111/ecog.01132.
[19] S. E. Fick, R. J. Hijmans, WorldClim 2: New 1-Km Spatial Resolution Climate Surfaces for Global Land Areas, International Journal of Climatology, Vol. 3, 2017, pp. 4302-4315, https://doi.org/10.1002/joc.5086.
[20] R. P. Anderson, A. Raza, The Effect of the Extent of the Study Region on GIS Models of Species Geographic Distributions and Estimates of Niche Evolution: Preliminary Tests with Montane Rodents (Genus Nephelomys) in Venezuela, Journal of Biogeography, Vol. 37, 2010,
pp. 1378-1393, https://doi.org/10.1111/j.1365-2699.2010.02290.x.
[21] J. M. Kass, R. Muscarella, P. J. Galante, C. L. Bohl, G. E. P. Buitrago, R. A. Boria, M. S. Guardia, R. P. Anderson, ENMeval 2.0: Redesigned for Customizable and Reproducible Modeling of Species’ Niches and Distributions, Methods in Ecology and Evolution,
Vol. 12, 2021, pp. 1602-1608, https://doi.org/10.1111/2041-210X.13628.
[22] J. Elith, S. J. Phillips, T. Hastie, M. Dudík, Y. E. Chee, C. J. Yates, A Statistical Explanation of Maxent for Ecologists, Diversity and Distributions, Vol. 17, 2011, pp. 43-57, https://doi.org/10.1111/j.1472-4642.2010.00725.x.
[23] D. Warren, S. Seifert, Ecological Niche Modeling in Maxent: The Importance of Model Complexity and the Performance of Model Selection Criteria. Ecological Applications, Vol. 21, 2011, pp. 335-342, https://doi.org/10.1890/10-1171.1.
[24] T. Vu, D. Tran, H. Tran, M. Nguyen, T. Do, N. Ta, H. Cao, N. Pham, D. Phan, An Assessment of the Impact of Climate Change on the Distribution of the Grey-Shanked Douc Pygathrix cinerea Using an Ecological Niche Model, Primates, Vol. 61, 2020, pp. 267-275, https://doi.org/10.1007/s10329-019-00763-8.
[25] B. M. Rawson, P. I. Cao, N. M. Ha, V. N. Tinh, H. M. Duc, S. Mahood, T. Geissmann, & C. Roos, The Conservation Status of Gibbons in Vietnam, Fauna & Flora International and Conservation International, Hanoi, 2011.
[26] C. Nhung, L. D. Minh, N. T. Anh, Modeling the Distribution of the Southern Yellow-Cheeked Gibbon (Nomascus gabriellae) Using Maxent, Vietnam Journal of Science and Technology,
Vol. 59, 2021, pp. 589-600, https://doi.org/10.15625/2525-2518/59/5/15890.
[27] O. Wearn, T. L. Nguyen, N. T. T. Huong, N. M. Phuong, T. V. Bang, N. H. Anh, N. V. Phuong, L. K. Quyet, N. D. Tho, E. C. Boucker, B. V. Tuan, H. Q. Huy, T. H. Vy, H. T. Long, Species Action Plan for the Grey-Shanked Douc Langur Pygathrix cinerea 2022 2030 with a Vision to 2050, Fauna & Flora International – Vietnam Programme, GreenViet, and the Frankfurt Zoological Society, Hanoi, 2022.
[28] N. T. Anh, N. T. Phong, T. T. D. Quynh, N. T. T. Ha, N. V. Thanh, P. V. Hung, L. D. Minh, Impacts of Climate Change on the Distribution of the Red-Shanked Douc (Pygathrix nemaeus), VNU Journal of Science: Earth and Environmental Sciences, Vol. 39, 2023, pp. 86-95, https://doi.org/10.25073/2588-1094/vnuees.4975 86.
[29] W. Helenbrook, J. Valdez, Role of Rivers As Geographical Barriers in Shaping Molecular Divergence of Neotropical Primates, Biotropica, Vol. 57, 2025, pp. 1-14, https://doi.org/10.1111/btp.70028.
[30] S. T. Turvey, C. L. Risley, J. E. Moore, L. A. Barrett, H. Yujiang, Z. Xiujiang, Z. Kaiya, W. Ding, Can Local Ecological Knowledge be Used to Assess Status and Extinction Drivers in a Threatened Freshwater Cetacean?, Biological Conservation, Vol. 157, 2013, pp. 352-360, https://doi.org/10.1016/j.biocon.2012.07.016.