Photo courtesy of ©Nguyen Van Truong. Used with permission.

Trachypithecus delacouri

Common names are not officially defined. They are based on everyday conversational language and may differ by country, region, profession, community, or other factors. As a result, it is not unusual for a species to have more than one common name.

Scientific names are in Latin and they are written in italics. They are standardized and for everyone, no matter what language you may speak. They are bound by a formal naming system, called binominal nomenclature, that has strict rules. Scientific names prevent misidentification. Those names only change if a species, or its genus, is officially redesignated by experts.

Delacour’s langurs are endemic to a small region of northern Vietnam just south of Hanoi. Their few remaining sub-populations mostly inhabit open subtropical rainforests. They spend most of their time on limestone rocks and in caves.

  • Delacour’s langurs are one of few mammal species who are trogloxenes, that is, they live part-time in caves
  • They shelter in caves for protection at night, switching cave locations every few days
  • They emerge just before sunrise to forage, travel, and rest in groups on their rocky cliffs
  • Teetering on the bring of extinction, only 200-250 individuals remain
  • The Delacour’s langur is one of the world’s 25 most endangered primate species
They are at an extremely high risk of becoming extinct in the wild.

According to the Vietnamese Journal of Primatology, of the 16 populations of Delacour’s langurs that existed in 2004, at least 6 had been eradicated by 2011. The majority of the remaining 10 populations only consist of one or two families, meaning that they are unlikely to survive in the long-term without intervention. Only the populations in Van Long Nature Reserve and possibly in Pu Luong Nature Reserve have enough monkeys to persist on their own. The langurs’ greatest threat is hunting. Both local and Chinese poachers hunt these monkeys so that their bones and tissues may be used in traditional medicines. The Vietnamese government has done very little to enforce its laws to protect the species. Although hundreds of poachers are arrested each year, only 10% are prosecuted. Delacour’s langurs are also threatened by habitat destruction.

  1. Delacour’s langurs are Critically Endangered wild animals. Their dietary and environmental needs cannot be adequately met or replicated in human living conditions. 
  2. To become pets, baby primates are stolen from their mothers. As a result, they do not develop normally emotionally.
  3. When taken from the wild, their mothers are killed to capture the baby.
  4. Trade in Critically Endangered species is illegal.
  5. Primates are never domesticated. They always remain wild. 
  6. Caged primates are very unhappy and frustrated. They are likely to resist confinement. They are quick and cause damaging bites and scratches. Some die as a result of their captivity.
  7. Many locations have strict regulations that prohibit trading in or keeping primates and endangered species are pets.
  8. Delacour’s langurs belong with other langurs in Vietnam. They and their habitats must be protected, not exploited.

Visit the DELACOUR’S LANGUR Primate Species Profile

 Copyright © New England Primate Conservancy 2019. You may freely use and share these learning activities for educational purposes. 
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