Critically Endangered Species (CR)

Critically endangered species are species that are facing an extremely high risk of extinction (according to IUCN). They are at the top of IUCN’s Red List of threatened species. In 2016, 7 primate species in Vietnam were included in this list, with 4 of them being endemic to Vietnam. The Eastern black gibbon was initially considered endemic to Vietnam as well, but since its distribution extends into Chinese territory, it has been removed from this list.

Unfortunately, the number of critically endangered primate species in Vietnam has sadly increased from 7 to 10.

Read more: 10 Endangered species of Primate in Vietnam

Detailed information about the 10 critically endangered Primate species.

Grey-shanked Douc (Pygathrix cinerea)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Cercopithecidae

Genus: Pygathrix

Species: Pygathrix cinerea

Image source: INaturalist (@Klaus Rudloff)

Primate

The Gray-shanked Douc langur was only discovered and officially announced in 1997 after being confiscated from illegal wildlife traders in 1995. It is the rarest species among the three douc langur species and also faces the most restricted habitat. It is listed as one of the 25 most critically endangered primate species in the world (Le Van Dung).

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It is a species endemic to Vietnam, ranging from Quang Nam to Binh Dinh. They are found in tropical forests on hills and mountains at elevations ranging from 200 to 1500 meters.

They have a relatively adaptable nature when forests are disturbed, but hunting has made populations of this species in Vietnam critically threatened.

Large populations are currently residing in Kon Ka Kinh National Park, the Song Thanh Nature Reserve, Dak Pring commune, and Kon Chu Rang.

Image source: IUCN

The gray-shanked douc langur has gray fur with white patches on its buttocks. Its shoulders and arms are black. The fur on its head is gray but with a black band above the forehead. They have white sideburns, while the fur on the neck is chestnut or reddish-brown. Their eyes are slightly cross-eyed. The arms of the douc langur are longer than its legs. It has a long tail with white fur.

Males are slightly larger than females and weigh an average of about 10.9 kg. Females weigh around 8.2 kg. As the name suggests, the gray-shanked douc langur has gray legs. Its arms are also gray. They are closely related to the red-shanked douc langur, while being distantly related to the black-shanked douc langur.

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Image source: Nguyen Van Truong

Gray-shanked douc langurs are diurnal and primarily arboreal. They move through tree branches by jumping and swinging. In the past, they were often found in large groups of up to 50 individuals, but this number has significantly decreased to 4 to 15 individuals now. Males are usually dominant and have a leadership role (Covert et al., 2008).

Gray-shanked douc langurs communicate with each other through touch, visual cues, and vocalizations. Growling is often a sign of anger and can be a threat display towards another individual. Soft whining sounds are usually a sign of submission. Gray-shanked douc langurs often groom their fur to remove parasites and strengthen the bonds between group members. This activity is usually performed before resting in the evening. Members can also show aggression by fighting, slapping, pulling, and grabbing each other (Covert et al., 2008).

Communication through visual cues includes facial expressions and different postures. Facial expressions can include wrinkling, indicating a submissive attitude, playful expressions when interacting with other members, and staring to show curiosity or anger. Facial expressions are also prominent during mate selection. Males will look towards females to indicate their readiness to mate. Their diet consists mainly of leaves, but they occasionally eat seeds, fruits, and flowers. They prefer young leaves and fruits.

Tonkin snub-nosed Monkey (Rhinopithecus avunculus)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Cercopithecidae

Genus: Rhinopithecus

Species: Rhinopithecus avunculus

Image source: @Le Khac Quyet

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The Tonkin snub-nosed Monkey is the representative species recorded in Vietnam. Four other species in the same genus are found in China and Myanmar. This species is listed as one of the 25 most critically endangered primate species in the world.

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Previously, this species was widely distributed in the eastern part of the Red River in Vietnam. However, hunting and deforestation have severely reduced their range and population. Currently, they are only recorded in two locations in Ha Giang province, where there are over 250 individuals living in pristine forests on steep limestone mountains.

Ha Giang may be the last stronghold for the remaining populations of snub-nosed monkeys in the world (Nguyen Van Truong).

Image source: IUCN

The multi-colored snub-nosed monkey has a distinctive snub-nosed face, thick lips, and dense fur (Le Khac Quyet). The fur on its back is dark brown, while the chest and abdomen are creamy white, with a patch of orange fur around the neck, especially in males.

They do not have a crest of hair on the top of their heads. The body length of the species ranges from 51 to 65 cm (20 to 26 inches), with a tail length of 66 to 92 cm (26 to 36 inches). Adult females and males weigh an average of 8 kg (18 lb) and 14 kg (31 lb) respectively. Mature individuals have grayish fur instead of black, and they do not have the orange fur around their neck.

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Image source: @Le Khac Quyet

Snub-nosed monkeys are nocturnal and their diet consists of a variety of leaves, fruits, flowers, and seeds. They live entirely in the trees, rarely descending to the ground, and move in small troops. A troop typically consists of one male and 10-15 females, rarely exceeding 20 females in a troop (Le Khac Quyet). They spend about 30% of their time resting during the day, with the remaining time dedicated to observation and foraging.

Cat ba langur (Trachypithecus poliocephalus)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Cercopithecidae

Genus: Trachypithecus

Species: Trachypithecus poliocephalus

Image source: naturepl.com (@Cyril Ruoso)

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The Cat Ba langur, also known as the Cat Ba golden-headed langur, is extremely rare worldwide and only exists on the Cat Ba archipelago in Ha Long Bay. It was once considered common, but this species has experienced a dramatic decline, and currently, there are only around 70 individuals remaining globally. They are also listed as one of the 25 most critically endangered primate species in the world.

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When the island of Cat Ba was still covered in dense forests, it could have been the habitat for a population of langurs numbering up to 2,700 individuals.

However, in the 1960s, this species began to be gradually eradicated due to hunting for meat and traditional medicine. People would trap entire langur troops while they slept in caves during the night.

They live in forests and shrubs covering the limestone mountains, with a male langur leading the troop and stopping at high points to survey the entire area before the troop moves on.

Image source: IUCN

It is true that the UNESCO designation of Ha Long Bay as a World Heritage site has not helped in the conservation of the langur species, but instead has led to rapid development of the town of Cat Ba. The uncontrolled disruption from tourism further threatens this species (Nguyen Van Truong).

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Reports have documented the movement of langur troops between islands during low tides. The isolation of small troops poses a long-term threat to their survival. The troop is led by a dominant male and consists of several females. Breeding occurs annually. When another male takes over leadership of the troop, they will kill the offspring to induce the females to enter into estrus sooner (infanticide behavior).

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(Image source: @Le Khac Quyet)

Delacour’s Langur (Trachypithecus delacouri)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Cercopithecidae

Genus: Trachypithecus

Species: Trachypithecus delacouri

Image source: @Le Khac Quyet

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The Delacour’s Langur has a narrow distribution range, only found in the northern region of Vietnam. It is estimated that there are around 200 individuals remaining, with 100 individuals concentrated in one area, while other areas are fragmented with small population sizes. This species is also listed as another member of the 25 most critically endangered primate species in the world.

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They live in evergreen forests and dense undergrowth. They are distributed at altitudes ranging from 500 to 1,000 meters on limestone mountains, where limited water sources restrict their distribution.

The largest population recorded consists of 100 individuals in the Vân Long Nature Reserve, Ninh Binh province.

Image source: IUCN

The body weight ranges from 8 to 9 kg, with a head and body length of 46 cm to 66.5 cm. They have black fur on the top of their heads, with broad white stripes on each side of the face that extend upwards towards the ears. Their legs have black fur. The buttocks have white fur that extends to the base of the tail and thighs, while the arms are long. The tail is longer than the body and has black fur. Their main diet consists of tree shoots, leaves, and fruits.

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Most of the remaining populations are small, with fewer than 20 individuals. One notable exception is a population of 30 to 40 individuals that still exists in the Pù Luông Nature Reserve, Thanh Hoa province, and another population, recently discovered at an undisclosed location. A troop consists of one adult male, several adult females, and their offspring.

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Image source: @Le Khac Quyet

Western Black Crested Gibbon (Nomascus concolor)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hylobatidae

Genus: Nomascus

Species: Nomascus concolor

Image source: INaturalist (@huangmp)

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This gibbon species is primarily distributed in northern Vietnam, Laos, and Yunnan province in China. The western black crested gibbon is a highly endangered species. There are currently fewer than 2,000 individuals worldwide, with only 60 individuals remaining in Vietnam.

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This species inhabits highland tropical forests ranging from 500 to 2,900 meters in elevation. However, its current distribution is fragmented due to deforestation and hunting. Previously, it could be found at elevations below 500 meters, but lowland forests have largely disappeared throughout its range.

In Vietnam, this species is only found in two protected areas, with approximately 20 troops in Mù Cang Chải Eco-reserve in Yen Bai province and the adjacent forest in Mường La, Son La province. There are also 2 to 5 troops in the Hoang Lien-Van Ban Nature Reserve in Lao Cai province.

Image source: IUCN

Recent research in China has shown that this species lives in small troops consisting of one adult male and two adult females. They are commonly known as “Fan Peng Fei” due to the tuft of hair on their foreheads. They have a head-to-tail length of 45 to 64 cm and weigh around 5.7 kg.

Their diet varies with the seasons as they inhabit high-altitude areas. Their food consists of approximately 50% leaves, 25% fruits, 19% figs, and 9% flowers (Zhao Chao | Cloud Mountain Conservation).

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Image source: wildwondersofchina

Eastern Black Crested Gibbon (Nomascus nasutus)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hylobatidae

Genus: Nomascus

Species: Nomascus nasutus

Image source: animalsworld.com (@huangmp)

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Currently, this species is limited to a single locality on the China-Vietnam border. However, in the past, it used to inhabit a range from the Red River to southeastern China. If the ongoing conservation efforts fail, there is a high risk of this species becoming extinct.

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There are approximately 130 individuals of this species worldwide, divided into 18 troops, with 14 of them located in Vietnam. As a result, the Cao Vit Gibbon Conservation Area was established in 2007, followed by the Bangliang Nature Reserve in China two years later in 2009. Both of these areas combined cover only about 2,000 hectares.

Surveys have not found this species in any other locations, suggesting that deforestation and hunting have led to a 99% decline compared to its previous population in northern Vietnam (Le Khac Quyet).

Image source: IUCN

Despite the hunting ban implemented since 2003, local residents have continued to encroach upon the habitat for logging and wood extraction, as well as for fuelwood.

The males of this species are predominantly black, while the females have a large white fur border around their faces and a black stripe on their foreheads. They primarily feed on fruits, but reports have also noted their consumption of small vertebrates and lizards (Le Khac Quyet).

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(Image source: bioexplore.net)

Females give birth during the coldest months, from October to February. Previously, they were found in tropical forests, including limestone mountains, ranging from 50 to nearly 1,000 meters in elevation. Small populations are highly vulnerable to inbreeding, diseases, and harsh weather conditions. It is challenging to mitigate the impacts on them effectively (Zhao Chao | Cloud Mountain Conservation).

Northern White-cheeked Crested Gibbon (Nomascus leucogenys)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hylobatidae

Genus: Nomascus

Species: Nomascus leucogenys

Image source: INaturalist (@ Staffan Widstrand/Wild Wonders of China)

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The white-cheeked gibbon, a highly endangered species, is found in southern Yunnan, China, northern Laos, and northwestern Vietnam. Despite their presence in eight protected areas in Vietnam, current measures are insufficient to halt their decline, and the risk of extinction for this species remains very high.

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This species currently exists mainly in small and isolated populations. Despite their presence in eight protected areas in Vietnam, these populations are too small to be viable, and they are at high risk of extinction. The largest population is estimated to be in Pu Mat National Park, with approximately 130 troops.

They inhabit evergreen and semi-evergreen forests at elevations ranging from 200 to 1,650 meters. The consequences of deforestation can be observed in the remaining populations found at higher elevations, such as in the Xuan Lien Nature Reserve.

Image source: IUCN

Like other members of the genus, both males and females of this species have unusually long arms, even for gibbons, with arms that are 1.2 to 1.4 times longer than their legs. They also have more muscular thighs and shoulders, indicating greater physical strength. Adult individuals prefer to use their hands when swinging through tree branches, with an equal preference for either the left or right hand among individuals.

This species is closely related to the black crested gibbon, but has slightly longer body hair and emits slightly different vocalizations. Male individuals of these two species can also be distinguished by the shape of the white patches on their cheeks; in the white-cheeked gibbon, the patches reach the upper edge of the ears and do not touch the corners of the mouth, while in the black crested gibbon, the patches only touch half of the ears and completely surround the lips.

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Image source: @Le Khac Quyet

Like other gibbon species, they live in monogamous pairs. In Vietnam, troops typically consist of 3-5 individuals. The white cheek fur of these species is only on the sides of the face, while the chin is a different color. They may consume fewer fruits compared to other gibbons because their distribution is further north (Fan Peng Fei).

Females can be distinguished by their richer fur coloration and a black tuft of hair on their heads (Nicolas Cornet). Pu Mat National Park nurtures 455 individuals and is the highest priority area for conserving this species in Vietnam. Its remote location near the Laos border is favorable for protection, although the development of roads through their habitats has threatened their survival.

Red-shanked Douc (Pygathrix nemaeus)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Cercopithecidae

Genus: Pygathrix

Species: Pygathrix nemaeus

Image source: @Thang Nguyen

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As the most colorful species among gibbons, the yellow-cheeked crested gibbon can be considered one of the most beautiful primates in the world. Found primarily in Laos and Vietnam, with occasional sightings in Cambodia, this species has a relatively large range. However, there is a high risk of them becoming critically endangered if conservation efforts are not improved.

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They are found at elevations ranging from sea level to 1,600 meters, inhabiting evergreen forests, limestone mountains, and deciduous forests.

Although they can be easily observed in the Son Tra Nature Reserve, the largest population in Vietnam is found in the Phong Nha-Ke Bang National Park.

Image source: IUCN

The leaves of trees are the main food source, accounting for about 80%. In Vietnam, 125 species of plants have been found in the diet of this species. The groups maintain either one male with multiple females, multiple males with multiple females, or multiple females. Each group usually consists of 5 to 10 individuals. Brown-footed langurs are still active in the rain as long as they do not get too wet (Hoang Ha).

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The Red-shanked Douc langur is the most brightly colored among the langur species. They are known as the “queen of langurs” due to their beautiful and unique appearance. From the knees to the ankles, the brown-footed langur has a “pair of long, reddish-brown stockings,” and their forearms are covered with a layer of white gloves. Their hands and feet, however, are black in color.

The Red-shanked Douc langur has a white, cap-like mustache, which is usually more prominent in males. They have a long white tail with a cluster of white fur at the end. The belly and back are gray in color. The fur on their body is a harmonious combination of five colors: black, gray, white, reddish-brown, and orange, which is why they are also called the five-colored langur.

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Image source: @Thang Nguyen

Adult individuals have an average body weight of around 11 kg for males and 8.44 kg for females. The average body length is about 61 cm for males and 55 cm for females. Their tail is tapered and measures between 55 and 76 cm in length. Male langurs have two tufts of white fur at the upper corners of the tail base, forming a triangular shape.

Black-shanked Douc (Pygathrix nigripes)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Cercopithecidae

Genus: Pygathrix

Species: Pygathrix nigripes

Image source: @Thang Nguyen

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Black-shanked douc langur is one of the langur species found in the Mekong River area, southern Vietnam, and eastern Cambodia. Their diet consists mainly of leaves. Their stomach is similar to that of a cow, with four compartments that allow them to digest cellulose in leaves.

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They are found in the semi-tropical forests, ranging from sea level up to 800 m in altitude. In Vietnam, their habitats include coastal forests in Nui Chua National Park, Ninh Thuan province, mixed forests in Cat Tien National Park, and mountainous tropical forests in Chu Yang Sin National Park, Dak Lak province.

Image source: IUCN

The black-shanked douc langur has a gray body with white fur on its buttocks. The shoulders and arms are black in color. The head has gray fur with a black band above the forehead. They have a white cap-like mustache, while the fur around the neck is brownish-red. Their eyes have a slight slant. The arms of the douc langur are longer than their legs. They have a long tail with white fur.

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The main difference between the three douc langur species lies in the fur from the buttocks downwards. As the name suggests, the black-shanked douc langur has black legs. Both arms are also black. Their diet consists mainly of leaves, occasionally supplemented with fruits and flowers.

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Image source: @tamphan_cbes

Unlike other monkey species, when faced with danger, they become motionless, making them vulnerable to hunting. They live in trees. During a day, two-thirds of their time is spent resting, while the remaining time is dedicated to eating and observing (Nguyen Van Truong).

Their diet consists of various types of leaves, occasionally fruits and seeds, with the proportions varying depending on the forest type (Le Khac Quyet). In Nui Chua National Park, the population of this species is estimated to be around 500-700 individuals (Jonathan C. Eames).

Southern White-cheeked Crested Gibbon (Nomascus siki)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hylobatidae

Genus: Nomascus

Species: Nomascus siki

Image source: @Linda De Volder

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This species was initially considered a subspecies of the Northern White-cheeked gibbon. They have a very small range in Central Laos and Vietnam. In Vietnam, this species is threatened by fragmented habitats and hunting, even within protected areas. In 2016, the IUCN listed them as endangered (EN) with an estimated population of 86 groups. However, in the latest update in 2020, they have been reclassified as critically endangered (CR), which is the highest conservation status, with an estimated population of only around 600 individuals.

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In Vietnam, this species inhabits tropical forests, including limestone mountains, ranging from 30 to 1800 meters in elevation. They are found in three protected areas: Phong Nha-Ke Bang National Park, Khe Nuoc Trong Nature Reserve in Quang Binh province, and Bac Huong Hoa Nature Reserve in Quang Tri province.

Image source: IUCN

This species is relatively unknown, and there is currently no research on their ecological behavior (Nicolas Cornet). In males, the white color on the face extends around the eyes but does not reach the ears. Females are more difficult to distinguish from the Northern White-cheeked gibbon (Jeremy Holden).

Adult Southern White-cheeked Crested Gibbons typically measure around 45 to 60 centimeters (18 to 24 inches) in length. They have a slender and agile body with long limbs. Their arms are longer than their legs, which enables them to have excellent brachiation (swinging from branch to branch) abilities.

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Image source: eprc.asia

The fur of Southern White-cheeked Crested Gibbons is predominantly gray. They have white fur on their cheeks, which extends to the sides of their face and neck. The fur on their head is gray with a black band above the forehead. 4. Facial Features: They have a prominent crest of hair on top of their head, which gives them their common name “crested gibbons.” Their face is characterized by a black ring around the eyes and a pinkish or flesh-colored face.

Males and females of this species have slight differences in appearance. Adult males usually have a more pronounced crest and a darker face compared to females. 6. Tail: Southern White-cheeked Crested Gibbons have a long tail, usually measuring around 60 to 70 centimeters (24 to 28 inches) in length. The tail is covered in white fur.

Primates Home Page
Primates Home Page

Conclusion

Here is the information about 10 critically endangered primate species in Vietnam that WANEE.ASIA would like to share with you. We hope that this will provide you with valuable insights into these 10 primate species. Wishing you the best experiences and wonderful exploration of nature.

Read more: Primate Watching Tours

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