Trachypithecus crepusculus | Indochinese Grey Langur
Good spot: Phu Khieo Wildlife Sanctuary, Chaiyaphum Province, Thailand
 Roos C., 2004. Molecular evolution and systematics of Vietnamese primates. In: Nadler T., Streicher U. and Ha Thang Long (eds), Conservation of primates in Vietnam, Frankfurt Zoological Society, Vietnam Primate Conservation Programme, Endangered Primate Rescue Center, Cuc Phuong National Park, Hanoi, Hanoi, Vietnam.
 Roos C., Vu Ngoc Thanh, Walter L. and Nadler T., 2007. Molecular systematics of Indochinese primates. Vietnamese Journal of Primatology 1 (issue 1): 41-53.
 Gibson L. and Koenig A., 2012. Neighboring groups and habitat edges modulate range use in Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus). Behavioral Ecology and Sociobiology 66: 633-643.
 Schülke O., Pesek D., Whitman B.J. and Ostner J., 2011. Ecology of Assamese macaques (Macaca assamensis) at Phu Khieo Wildlife Sanctuary, Thailand. Journal of Wildlife in Thailand 18: 1–15.
Page Last Updated: 28 September 2018
Trachypithecus crepusculus is a monotypic species (no subspecies).
Southwestern China, Lao PDR, Myanmar, Thailand, northern Vietnam
IUCN Conservation Status
Endangered (under T. phayrei crepuscula)
Previously recognized as a subspecies of Phayre's Langur, the Indochinese Grey Langur is now a distinct species based on molecular data [1,2]
Seeing this Species
Phu Khieo Wildlife Sanctuary, Thailand
At least three habituated groups of grey langurs live here. Researchers note that the langurs "primarily inhabit the dry ever- green forest of Huai Mai Sot Yai . However, they also used the edge between dry evergreen and dry dipterocarp forest, and they may (very rarely) cross small patches of dry dipterocarp forest on the ground."
Probability of Success: not bad if they're habituated...
Overlapping species: Sunda Slow Loris, Assamese Macaque, Northern Pig-tailed Macaque, Rhesus Macaque, Stump-tailed Macaque, White-handed Gibbon
Perhaps surprisingly Long-tailed Macaque does not occur here, even though the park is home to the other four of Thailand's five species of macaques .