Red-shanked douc langur (Pygathrix nemaeus) is a primate species of the family Cercopithecidae (i.e. Old World monkeys) that is endemic to Indochina (Vietnam, Lao DPR, and Cambodia). The name “Douc” /dook/ arises by how this langur sounds, which is also known as onomatopoeia – a creation of a word from a sound related to what is named. This primate is also called “Voọc”, an ancient Vietnamese word meaning “Monkey”. Thanks to the resplendent costume, Red-shanked douc langur is globally acknowledged as the “Queen of Primates”.

 

Other names: Costumed ape, Queens (English); Voọc chà vá chân đỏ, Voọc vá chân nâu, Voọc chà vá, Voọc ngũ sắc (Vietnamese); Rotschenkligen Kleiderapffe (German); Langur de patas rojas (Español).

 

 

APPEARANCE

 

Red-shanked doucs are one of the most visually dazzling monkeys in the world. Red-shanked doucs have a yellow-brown face surrounded by white whiskers, white throat followed by an orange collar. The shoulders, hands, and feet are black. The abdomen and back are silver. The wrists are white. Also, they attain stunning red legs, hence the name red-shanked doucs! Thanks to these eye-catching features, they are known as “The Queens of Primates”.

 

Infants are born with light grey fur and their faces are black with two pale strips under the eyes. When they get older, the faces lighten and bodies darken and eventually become resplendent with colours similar to the adults.

 

The head-to-body length of male doucs is from 55-82 cm while that of the female counterparts ranges from 60-63 cm. The tail length of male and female doucs is 56-74 cm and 44-60 cm, respectively [1]. Sexual dimorphism in this species can be shown by the size in which males are larger than females. Male’s whiskers are also more prominent than females. When sitting, females hardly ever sit with their genitals exposed while males tend to stretch two legs on both sides and expose their red genitals. Besides, the male douc langurs possess a big round belly, which is also joked as “Beer belly”.

 

 

 

 

 

GEOGRAPHIC DISTRIBUTION AND HABITAT

 

Red-shanked doucs are found to inhabit primary and secondary evergreen and semi-evergreen forests as well as forests on limestone at an altitude of 0 to 1,700 m above sea level in Lao DPR, Cambodia, and Vietnam [2]. 

 

In Lao DPR, they are found from Phou Chomvoy Provincial Protected Area down onto the Cambodia border. This is the country where the world’s largest population of the red-shanked douc can be found, with an estimate of approximately 4,500 groups in Nakai – Nam Theun Protected Area [2,3]. Large numbers were also recorded in other locations such as Hin Namno and Xe Sap National Protected Area. In Cambodia, the animals are believed to inhabit Virachay National Park and a forested area in Voensai District.

 

In Vietnam, red-shanked doucs are widely distributed across several national parks such as Pu Mat (Nghe An), Vu Quang (Ha Tinh), Phong Nha – Ke Bang (Quang Binh), Bach Ma (Thua Thien Hue), and Chu Mom Ray (Kon Tum); as well as nature reserves including Son Tra, Ba Na – Nui Chua, Nam Hai Van (Da Nang), and the Saola Reserve (Kon Tum) [2,3]. The  largest population  of the  red-shanked  douc  langurs is thought to be Phong Nha – Ke Bang National Park with the  size ranging  from  400  to  over 2,000 individuals [3,4]. In Son Tra, it is estimated that there are about 1,300 individuals clinging to the forest of this peninsula, making it one of the largest red-shanked douc populations remaining in Vietnam [5]. The red-shanked doucs of Son Tra have become a major attraction for both Da Nang locals and international visitors. During the blooming seasons of yellow flame trees (Peltophorum pterocarpum) and purple than mat (Millettia nigrescens gagnep), many people—especially wildlife photographers—flock to Son Tra to capture stunning images of these ‘Queens of the Forest’ beneath golden and purple blossoms.

 

 

 

 

DIET

 

Red-shanked doucs are folivorous; they primarily feed on leaves, along with fruits and flowers. In general, their diet includes 87.8% leaves, 10.2% fruits and seeds, 1.6% flowers, and 0.4% bark [3].

 

 

LIFESTYLE

 

Red-shanked doucs are arboreal and diurnal species. They spend their time mostly on the trees and are active during the day. Doucs swing from branch to branch by brachiation or jump with two feet. Most of the time is spent on foraging and socializing. 

 

Red-shanked doucs follow a “Fission-Fusion” society, where they split into smaller groups during the morning and fused into a big group of up to 30-50 individuals at night [1,2]. Smaller groups include one-male groups, pair-bonded groups, and multi-male groups.

 

Communications are made using vocalizations, postures, and touch. Red-shanked doucs also participate in allogrooming to tighten group bonds.

 

 

 

REPRODUCTION AND FAMILY

 

The reproduction season occurs from February to June with a gestation period of 165-190 days. Each birth yields one offspring, and twins are extremely rare. Infants are born with their eyes open and constitutively cling to their mothers, they are usually cared for by other female members in a group. Males reach maturity at the age of 4 to 5, whereas females become mature after four years. The life span is 20-25 years [2,4].

 

ECOLOGICAL ROLE

 

Red-shanked douc langurs are essential seed dispersers as they get involved in spreading undigested seeds from the fruits, thereby facilitating plant growth and plant diversity of the habitat [2].

 

CONSERVATION STATUS AND EFFORTS

 

The International Union for Conservation of Nature lists red-shanked douc langur as “Critically Endangered”. Currently, this beautiful primate species is tackling constant threats, mainly from human activities, such as fragmented habitat, habitat loss due to deforestation, land encroachment and agricultural conversion. They are also hunted for meats, traditional medicines, and pet trade. This species is listed in Appendix I of the CITES Convention and is strictly protected under Vietnamese law, specifically Government Decrees No. 64/2019/ND-CP and No. 84/2021/ND-CP [2,3].

 

A wide range of conservation strategies has been worked out to protect the species, including a breeding program at the Endangered Primate Rescue Center at Cuc Phuong National Park [5]. The Center for Technology and Nature Conservation (CTNC) also launched a conservation project in 2024 to safeguard the red-shanked douc langurs’ population in the Hai Van Pass area (Bac Hai Van Protection Forest) [6].

 

Since Son Tra has its natural habitats fragmented by roads for tourism, a project called “Canopy bridges” was proposed by Son Tra Douc langur Research and Conservation Project from Frankfurt Zoological Society (FZS) [7]. These bridges will be planted and maintained to connect the ever-divided habitats in Son Tra so that every red-shanked douc can get to the other side at ease without conflicts with vehicles. The project has reached realization as photos of doucs using bridges have been captured.

 

 

All of this being said, conservation activities like propaganda, breeding programs, habitat protection, and sustainable ecotourism are of tremendous essence to keep the populations of red-shanked douc langurs thrive on and exist for years to come.

 

WHAT IS HIVOOC DOING TO CONSERVE THIS SPECIES IN SON TRA PENINSULA 

 

We HiVOOC are aware that protecting the majestic red-shanked douc langurs is not a choice, but a shared mission. As a wildlife tour company, HiVOOC introduces sustainable ecotours in Son Tra in which tourists 

 

Starting with education, we have operated numerous educational and experiential programs for students to raise public awareness about this langur. One of them is “VỌOC ƠI, MÌNH ĐI ĐÂU THẾ?”, a free program for children to experience the wilderness of Son Tra and observe the red-shanked doucs. This outdoor activity gains recognition from not only both students and parents but also from educational authorities and environmental organizations across the region.

 

REFERENCES

 

1. New England Primate Conservancy. (n.d.). Red-shanked douc langur. https://neprimateconservancy.org/red-shanked-douc-langur/

2. Coudrat, C.N.Z., Quyet, L.K., Duc, H., Phiaphalath, P., Rawson, B.M., Nadler, T., Ulibarri, L. & Duckworth, J.W. 2020. Pygathrix nemaeus. The IUCN Red List of Threatened Species 2020: e.T39826A17941247. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T39826A17941247.en. Accessed on 04 May 2025.

3. Nguyễn Đình Duy, Trịnh Đình Hoàng, Nguyễn Vĩnh Thanh, Hà Thăng Long, 2023. Pygathrix nemaeus. Danh lục Đỏ Việt Nam. MM12

4. Nguyen, V. M. (2019). Conservation of the red-shanked douc langurs (Pygathrix nemaeus) in Bach Ma National Park: An update on distribution and population size. Journal of Forestry Science and Technology, 2019(1), 70–77. https://journal.vnuf.edu.vn/en/article/view/793/705

5. Nadler, T., Thanh, V. N., & Streicher, U. (2007). Conservation status of Vietnamese primates. Vietnamese Journal of Primatology, 1(1), 7-26.

6. Center for Technology and Nature Conservation. (2024, April 3). Launches comprehensive conservation project for Red-shanked Douc (Pygathrix nemaeus) in Hai Van Pass. https://eng.ctnc.org.vn/launches-comprehensive-conservation-project-for-red-shanked-douc-pygathrix-nemaeus-in-hai-van-pass/

7. Ulibarri, L., & Streicher, U. (2012). The “Son Tra douc langur research and conservation project” of Frankfurt Zoological Society. Vietnamese Journal of Primatology, 2(1), 37-46.

 

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