#langur — Public Fediverse posts

Sporting bold facial stripes, the Thomas’s #Langur is a handsome icon of #Sumatra #Indonesia 🇮🇩 Threats include #palmoil #deforestation and human persecution 🏹😿 Fight for their survival and #BoycottPalmOil 🌴🪔☠️🩸🤮🙊🚫 #Boycott4Wildlife @palmoildetectives https://palmoildetectives.com/2021/01/24/thomass-langur-presbytis-thomasi/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

Sporting bold facial stripes, the Thomas’s #Langur is a handsome icon of #Sumatra #Indonesia 🇮🇩 Threats include #palmoil #deforestation and human persecution 🏹😿 Fight for their survival and #BoycottPalmOil 🌴🪔☠️🩸🤮🙊🚫 #Boycott4Wildlife @palmoildetectives https://palmoildetectives.com/2021/01/24/thomass-langur-presbytis-thomasi/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

In the forests of #Bangladesh 🇧🇩 and northern #India 🇮🇳 lives a remarkable #primate with soulful hazel eyes 🐵🐒 on the verge of #extinction from #palmoil #deforestation. Help the Capped #Langur and #Boycottpalmoil 🌴🔥🚫 #Boycott4Wildlife @palmoildetectives https://palmoildetectives.com/2026/01/11/capped-langur-trachypithecus-pileatus/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

Beautiful and Doomed: Saving Bangladesh’s Langurs From Extinction

A recent study has found hybridisation (interbreeding) between critically endangered Phayre’s #langurs and endangered capped langurs in #Bangladesh, raises serious concerns about their genetic health and future survival as distinct species. Hybridisation is a serious sign of ecological disruption, and researchers point to human-related threats such as #palmoil and #timber #deforestation, habitat fragmentation, and #hunting as key drivers for them interbreeding. These pressures not only push the species to hybridise but also threaten their long-term existence in the wild, highlighting the urgent need for conservation efforts to address habitat destruction and protect these seriously endangered primates. 🌿 Help them when you shop, go #vegan and #BoycottPalmOil #Boycott4Wildlife

Beautiful Capped Langurs and Phayre’s #Langurs are interbreeding, risking both #species’ survival. Pressures of #palmoil #deforestation and #hunting are pushing the #monkeys to the edge in #Bangladesh #Boycottpalmoil #Boycott4Wildlife 🌴🚫 @palmoildetect https://wp.me/pcFhgU-9bY

Hybridisation/interbreeding of two beautiful #langur 🐵🐒species in #Bangladesh puts both #animals in serious peril finds #research study 😭. #Palmoil #deforestation is a major threat. Fight back and #Boycottpalmoil #Boycott4Wildlife 🌴🛢️⛔ @palmoildetect.bsky.social https://wp.me/pcFhgU-9bY

This article was originally published in Mongabay and was written by Mohammad Al-Masum Molla, read the original article. Republished under Creative Commons attribution licence. Research by Ahmed, T., Hasan, S., Nath, S., Biswas, S. … Roos, C. (2024). Mixed-Species Groups and Genetically Confirmed Hybridization Between Sympatric Phayre’s Langur (Trachypithecus phayrei) and Capped Langur (T. pileatus) in Northeast Bangladesh. International Journal of Primatology. doi:10.1007/s10764-024-00459-x

• Bangladesh is home to less than 500 Phayre’s langurs and 600 capped langurs in the rainforests in the country’s northeast.
• A recent study has unveiled a trend of hybridisation between Phayre’s langurs and capped langurs in Bangladesh, which are listed as critically endangered and endangered, respectively, by IUCN.
• Hybridisation is a vital indicator of ecological change, and researchers are raising serious concerns about the genetic health of the two species and their future existence in the wild.
• The study holds human activities such as deforestation, habitat fragmentation and hunting as some of the causes responsible for increasing the risk of hybridisation cases.

A recent study revealed a troubling trend among the wild monkey population in Bangladesh’s northeastern forests. The study, conducted by the German Primate Centre, unveiled a concerning tendency of hybridisation between Phayre’s langurs (Trachypithecus phayrei) and capped langurs (Trachypithecus pileatus), listed as critically endangered and endangered, respectively, within Bangladesh by IUCN.

This hybridisation of the endangered primates, which researchers of the study say is caused by habitat loss due to deforestation and other human interferences, could push them to extinction in a few generations.

“Bangladesh’s langur populations are small and isolated, limiting gene flow. This hybridisation in restricted populations heightens their extinction risk. Furthermore, our laws primarily protect pure langurs, leaving hybrids unprotected. If hybrids persist into future generations, we’ll face tough decisions about their role in our ecosystem,” Tanvir Ahmed, the study’s lead researcher, told Mongabay.

Monirul H. Khan, a professor at Jahangirnagar University’s Zoology Department, agreed with Tanvir and said that the significance of interbreeding is that these langurs don’t survive for a long time.

“They are usually born infertile. So the population of langur will gradually decrease,” he said.

The study, published in the International Journal of Primatology, recently found that out of 98 langur groups observed, eight comprised both Phayre’s and capped langurs.

“We analysed genetic samples of the species in the lab and confirmed one case of hybridisation. This langur had a capped langur mother and a Phayre’s langur father. Another female with a hybrid appearance showed signs of motherhood, indicating that at least female hybrids are fertile and give birth to young,” Tanvir said.

“The genetic characteristics of a distinct species tend to become most threatened when their hybrid females can reproduce. Fertile hybrid females threaten to bring the two species closer together as the offsprings begin to mix characteristics. That is exactly what could be happening to them,” he said.

The research shows that the ‘spectacled’ Phayre’s langurs and the capped langurs, with their distinctive shock of black fur on their heads, are under threat of losing their distinct genetic makeup to hybridisation.

Researchers conducted the study over five years, between 2018 and 2023, in six forests in northeastern Bangladesh — Lawachara National Park, Satchari National Park, Rema-Kalenga Wildlife Sanctuary, Rajkandi Reserve Forest, Patharia Hill Reserve Forest and Atora Hill Reserve Forest.

The study involved field surveys for 92 days between March 2018 and April 2019 and from July to December 2022, employing three trained local eco-guides to monitor the mixed-species groups until October 2023.

Why hybridisation is a concern

The study shows that, although it’s relatively rare, hybridisation among primates is an escalating concern worldwide, often driven by habitat loss and fragmentation. It serves as a stark reminder of the significant impacts of human activity on biodiversity. The situation in Bangladesh gradually becoming more common emphasizes the urgent need for strong conservation efforts.

The study mentions how hybridisation is a vital indicator of ecological change, raising serious concerns about species’ genetic health. Tanvir added that this study is groundbreaking, as it documents the first hybridisation incidents among these langurs in Bangladesh and their entire distribution range.

Hybrids being fertile could lead to the extinction of the parent species. “Additionally, mixing species can enable the spread of diseases between previously unconnected populations, posing risks to both wildlife and human health, since these animals are often hunted and traded,” said Sabit Hasan, a researcher of the study.

The study blamed human activities such as palm oil deforestation, habitat fragmentation, hunting and trapping of primates as some of the causes that can increase the risk of such hybridisation.

“The existence of fertile hybrids is particularly alarming because it suggests that gene flow between these two endangered species could irreversibly affect their future genetic composition,” Tanvir said.

Primates of Bangladesh

Ten of the 121 mammal species found in Bangladesh are primates. According to the hybridisation study, Bangladesh is home to less than 500 Phayre’s langurs and 600 capped langurs.

The Phayre’s langur has a brown to grey-brown back, white fur on its belly and face, and a “spectacled” appearance due to wide white rings around its eyes. Its face and extremities are black, and it has long hair on its head that points backward. Additionally, its tail is longer than its body and has a tuft of dark hair at the tip.

The capped langur is known for its distinctive crown of long, erect hairs on its head. It has a black face, grey to blackish-grey fur on top, and brownish-yellow or orange fur below, with the distal half of its tail being blackish.

The study suggested the government prioritize habitat preservation and create corridors to connect isolated primate populations, facilitating natural langur dispersal.

“If we don’t take action now, we risk losing not just two monkey species but also a vital part of Bangladesh’s biodiversity,” Tanvir said.

Banner image: The genetically confirmed hybrid (right) with its capped langur mother at Satchari National Park. Image by Harish Debbarma.

This article was originally published in Mongabay and was written by Mohammad Al-Masum Molla, read the original article. Republished under Creative Commons attribution licence. Research by Ahmed, T., Hasan, S., Nath, S., Biswas, S. … Roos, C. (2024). Mixed-Species Groups and Genetically Confirmed Hybridization Between Sympatric Phayre’s Langur (Trachypithecus phayrei) and Capped Langur (T. pileatus) in Northeast Bangladesh. International Journal of Primatology. doi:10.1007/s10764-024-00459-x

ENDS

Learn about other animals endangered by palm oil and other agriculture

Sunda Flying Lemur Galeopterus variegatus

Western Parotia Parotia sefilata

Capped Langur Trachypithecus pileatus

Mountain Tapir Tapirus pinchaque

Saola Pseudoryx nghetinhensis

Tucuxi Sotalia fluviatilis

Learn about “sustainable” palm oil greenwashing

Read more about RSPO greenwashing

A 2019 World Health Organisation (WHO) report into the palm oil industry and RSPO finds extensive greenwashing of palm oil deforestation and the murder of endangered animals (i.e. biodiversity loss)

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In the forests of #Bangladesh 🇧🇩 and northern #India 🇮🇳 lives a remarkable #primate with soulful hazel eyes 🐵🐒 on the verge of #extinction from #palmoil #deforestation. Help the Capped #Langur and #Boycottpalmoil 🌴🔥🚫 #Boycott4Wildlife @palmoildetect.bsky.social https://palmoildetectives.com/2026/01/11/capped-langur-trachypithecus-pileatus/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

Sporting bold facial stripes, the Thomas's #Langur is a handsome icon of #Sumatra #Indonesia 🇮🇩 Threats include #palmoil #deforestation and human persecution 🏹😿 Fight for their survival and #BoycottPalmOil 🌴🪔☠️🩸🤮🙊🚫 #Boycott4Wildlife @palmoildetect.bsky.social https://palmoildetectives.com/2021/01/24/thomass-langur-presbytis-thomasi/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

The intelligent and social Capped #Langur 🙉🐒🐵 is under pressure from #palmoil #deforestation and hunting in #India 🇮🇳 Troops are interbreeding with Phayre's #langurs to survive. Fight for them and #Boycottpalmoil 🌴☠️❌ #Boycott4Wildlife

http://palmoildetectives.com/2026/01/11/capped-langur-trachypithecus-pileatus/?utm_source=mastodon&utm_medium=jetpack_social

Capped Langur Trachypithecus pileatus

Capped Langur Trachypithecus pileatus

IUCN Red List Status: Vulnerable

Location: India, Bhutan, Bangladesh, Myanmar

This species inhabits subtropical and tropical dry forests, primarily in the foothills and highlands south of the Brahmaputra River and across fragmented patches in northeastern South Asia.

The capped #langur (Trachypithecus pileatus) is a graceful and beautiful leaf #monkey found across northeastern #India, #Bhutan, #Bangladesh, and #Myanmar. Sadly, they are listed as #Vulnerable on the IUCN Red List due to rapid population declines from #deforestation, logging, agriculture, and the devastating impacts of #palmoil plantations. Once widespread, their numbers have nearly halved in some regions like Assam due to the accelerating loss of native forest cover. Directly threatened by palm oil and monoculture expansion, this species is now confined to small, isolated forest fragments. Take action every time you shop and #BoycottPalmOil #Boycott4Wildlife

https://youtu.be/NhpTmfZuNV4

In the forests of #Bangladesh 🇧🇩 and northern #India 🇮🇳 lives a remarkable #primate with soulful hazel eyes 🐵🐒 on the verge of #extinction from #palmoil #deforestation. Help the Capped #Langur and #Boycottpalmoil 🌴🔥🚫 #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2026/01/11/capped-langur-trachypithecus-pileatus/

The intelligent and social Capped #Langur 🙉🐒🐵 is under pressure from #palmoil #deforestation and hunting in #India 🇮🇳 Troops are interbreeding with Phayre’s #langurs to survive. Fight for them and #Boycottpalmoil 🌴☠️❌ #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2026/01/11/capped-langur-trachypithecus-pileatus/

Appearance & Behaviour

With their black-tufted crown, pale fur, and soulful eyes, capped langurs are among the most visually distinctive primates in the Eastern Himalayas. Their fur ranges from silver-grey to golden orange, with darker limbs and a black cap that gives them their name. They move gracefully through the canopy, rarely descending to the forest floor except for play or social grooming.

Capped langurs live in unimale, multifemale groups with sizes ranging from 8 to 15 individuals. They spend most of their time feeding (up to 67%) or resting (up to 40%), engaging in complex social grooming and vocal communication. Daily movements range from 320–800 metres across fragmented habitats of 21–64 hectares. Grooming is an important social activity, with females often taking turns in allomothering behaviour.

Threats

Palm oil, teak and rubber monoculture plantations

The spread of oil palm and other monoculture crops such as teak and rubber is destroying the capped langur’s native forests at an alarming rate. These industrial plantations eliminate the diverse tree species that capped langurs rely on for food and shelter, leaving them with little to survive on. Once a landscape is cleared and replaced with palm oil or other single crops, it becomes a green desert devoid of biodiversity, pushing the species closer to extinction. In regions like Assam and Bangladesh, palm oil is a major driver of habitat fragmentation and degradation, especially in forest corridors that once connected populations.

Timber deforestation

Widespread illegal logging, often fuelled by demand for timber and firewood, is rapidly eroding the capped langur’s habitat. Fruiting and lodging trees that are vital to their survival are cut down, leaving forests patchy and disconnected. As their home ranges shrink, capped langur groups are forced into smaller fragments, increasing their vulnerability to predators, food shortages, and inbreeding. In some areas, this pressure has led to local extinctions or the collapse of entire populations.

Slash-and-burn agriculture

Slash-and-burn agriculture destroys habitat for capped langurs and often brings them into closer contact with human settlements, increasing conflict and risk of hunting or roadkill. Forest recovery from this can take decades—time the capped langur simply doesn’t have.

Hunting and the illegal pet trade

Capped langurs are hunted for their meat, pelts, and for sale in the illegal pet trade. In many tribal and rural areas of Assam, Arunachal Pradesh, and Manipur, they are still targeted despite legal protections. Their pelts are used to make traditional knife sheaths, and infants are often captured after killing their mothers, then sold as pets. This exploitation causes severe suffering and has a devastating impact on group structures, leading to long-term population decline.

Roads cut into rainforests for mines and tea plantations

As forests are cut into smaller patches for roads, mining, tea plantations, and settlements, capped langur populations become increasingly isolated. Small, disconnected populations face higher risks of inbreeding, loss of genetic diversity, and eventual extinction. In some regions, such as Tinsukia and Sonitpur, populations have already disappeared due to this fragmentation. The collapse of corridors also disrupts daily movement, feeding patterns, and access to mates—placing enormous stress on surviving individuals.

Hybridisation with other species

Due to the rapid degradation of natural habitats, capped langurs are increasingly forming mixed-species groups with the closely related Phayre’s langur (Trachypithecus phayrei). Recent studies in northeast Bangladesh confirm genetically that hybridisation is occurring, which could result in the eventual cyto-nuclear extinction of the capped langur lineage. Although hybridisation can happen naturally, in this case it is being driven by human-induced fragmentation, forcing species into overlapping territories with fewer options for mates. This phenomenon is both a symptom and a driver of their decline, complicating conservation efforts.

Mining, infrastructure, and political conflict

Open-cast coal mining, limestone extraction, and petroleum exploration have all contributed to the destruction of capped langur habitat across Assam and Nagaland. Infrastructure projects, such as highways and border fences, not only destroy habitat directly but also block animal movements and isolate populations. In border regions, armed conflict and territorial skirmishes have already extirpated capped langurs from several reserves, such as the Nambhur and Rengma forests. Weak law enforcement allows habitat destruction to continue unchecked in many regions.

Geographic Range

Capped langurs are found in northeastern India (Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram, and Tripura), Bhutan, northwestern Myanmar, and northeastern and central Bangladesh. They occur at elevations from 10 to 3,000 metres across hill forests, riverine reserves, and protected areas. However, their range is now severely fragmented by human development, with some populations disappearing from former strongholds due to mining, conflict, and agricultural encroachment.

Diet

Primarily folivorous, the capped langur’s diet includes mature and young leaves, petioles, seeds, flowers, bamboo shoots, bark, and occasionally caterpillars. They forage on more than 43 plant species, with favourites including banyan (Ficus benghalensis), sacred fig (Ficus religiosa), Terminalia bellerica, and Mallotus philippensis. Seasonal availability influences their feeding patterns, but they consistently prefer fruiting and flowering trees.

Mating and Reproduction

Breeding usually occurs in the dry season, with birthing concentrated between late December and May. The gestation period lasts about 200 days, and the interbirth interval is approximately two years. Only parous females participate in allomothering, allowing new mothers time to forage and recover, a behaviour rare among langurs and considered a form of altruism.

FAQs

How many capped langurs are left in the wild?

Exact numbers are uncertain, but estimates suggest the population in Assam has declined from 39,000 in 1989 to approximately 18,600 between 2008 and 2014 (Choudhury, 2014). This halving reflects habitat loss and increasing fragmentation, particularly in Upper Assam and the Barak Valley.

What is the average lifespan of a capped langur?

While data is limited, langurs of this genus generally live 20–25 years in the wild. Captive lifespans may extend slightly due to the absence of predators and constant food supply, though such conditions often lead to stress.

Why are capped langurs under threat?

Their decline is due to relentless deforestation, palm oil and monoculture plantations, illegal logging, and road-building. Slash-and-burn agriculture and mining also play a major role. Capped langurs are hunted in some regions for meat, pelts, and as pets, particularly in Assam, Arunachal Pradesh, and Nagaland.

Do capped langurs make good pets?

Absolutely not. Capped langurs are intelligent, social beings that rely on complex forest habitats and close-knit family groups. Removing them from the wild fuels extinction and causes immense trauma. Many die during illegal capture and transport. Keeping them as pets is a selfish act that destroys lives. If you care about capped langurs, never support the exotic pet trade!

What are the major conservation challenges for capped langurs?

The biggest issues are hybridisation with other primate species, habitat fragmentation, palm oil expansion, and human-wildlife conflict. The 2018 study in Satchari National Park found that local attitudes toward conservation vary by occupation, education, and gender, which means education and outreach are crucial. A big challenge is the rise in hybridisation with sympatric Phayre’s langurs, driven by habitat degradation—this poses long-term genetic risks (Ahmed et al., 2024).

Take Action!

Capped langurs are vanishing before our eyes, driven to the brink by out-of-control palm oil expansion, deforestation, and development. You can help save them.

Refuse to buy products made with palm oil. Support indigenous-led conservation in northeast India and the Eastern Himalayas. Demand governments halt the destruction of old-growth forests and restore wildlife corridors. Spread awareness and challenge the illegal wildlife trade. #BoycottPalmOil #Boycott4Wildlife #Vegan #BoycottMeat

Support the Capped Langur by going vegan and boycotting palm oil in the supermarket, it’s the #Boycott4Wildlife

Support the conservation of this species

This animal has no protections in place. Read about other forgotten species here. Create art to support this forgotten animal or raise awareness about them by sharing this post and using the #Boycottpalmoil #Boycott4Wildlife hashtags on social media. Also you can boycott palm oil in the supermarket.

Further Information

Ahmed, T., Hasan, S., Nath, S., Biswas, S., et al. (2024). Mixed-Species Groups and Genetically Confirmed Hybridization Between Sympatric Phayre’s Langur (Trachypithecus phayrei) and Capped Langur (T. pileatus) in Northeast Bangladesh. International Journal of Primatology, 46(1), 210–228. https://doi.org/10.1007/s10764-024-00459-x

Das, J., Chetry, D., Choudhury, A.U., & Bleisch, W. (2020). Trachypithecus pileatus (errata version published in 2021). The IUCN Red List of Threatened Species 2020: e.T22041A196580469. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T22041A196580469.en

Hasan, M.A.U., & Neha, S.A. (2018). Group size, composition and conservation challenges of capped langur (Trachypithecus pileatus) in Satchari National Park, Bangladesh. Retrieved from https://www.researchgate.net/publication/339550399

Wikipedia. (n.d.). Capped langur. Retrieved April 6, 2025, from https://en.wikipedia.org/wiki/Capped_langur

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Read more

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Read more

3. Supermarket sleuthing: Next time you’re in the supermarket, take photos of products containing palm oil. Share these to social media along with the hashtags to call out the greenwashing and ecocide of the brands who use palm oil. You can also take photos of palm oil free products and congratulate brands when they go palm oil free.

https://twitter.com/CuriousApe4/status/1526136783557529600?s=20

https://twitter.com/PhillDixon1/status/1749010345555788144?s=20

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4. Take to the streets: Get in touch with Palm Oil Detectives to find out more.

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Learn about other animals endangered by palm oil and other agriculture

Mountain Tapir Tapirus pinchaque

Keep reading

Saola Pseudoryx nghetinhensis

Keep reading

Tucuxi Sotalia fluviatilis

Keep reading

Frill-Necked Lizard Chlamydosaurus kingii

Keep reading

Grey Crowned Crane Balearica regulorum

Keep reading

Ecuadorean Viscacha Lagidium ahuacaense

Keep reading

Learn about “sustainable” palm oil greenwashing

Read more about RSPO greenwashing

A 2019 World Health Organisation (WHO) report into the palm oil industry and RSPO finds extensive greenwashing of palm oil deforestation and the murder of endangered animals (i.e. biodiversity loss)

#animals #Assam #Bangladesh #Bantrophyhunting #Bhutan #Boycott4wildlife #BoycottMeat #BoycottPalmOil #CappedLangurTrachypithecusPileatus #deforestation #extinction #ForgottenAnimals #humanWildlifeConflict #hunting #illegalPetTrade #India #langur #Langurs #mining #monkey #monkeys #Myanmar #PalmOil #palmOilDeforestation #palmoil #PhayreSLeafMonkeyTrachypithecusPhayrei #poaching #Primate #vegan #vulnerable #VulnerableSpecies

The world's most endangered #langur, the Popa Langur has striking lilac coloured fur 🐒💜🪻 and white rimmed expressive eyes. Discovered in 2020 now critically #endangered 😿 Fight for them and #BoycottPalmOil 🌴🪔🙊🔥🤮⛔️#Boycott4Wildlife @palmoildetect.bsky.social https://palmoildetectives.com/2021/01/25/popa-langur-trachypithecus-popa/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

Forgotten #primate 🙊🐒 Pig-tailed Snub-nosed #Langur is now critically endangered on tiny islands near #Sumatra #Indonesia 🇮🇩 from #palmoil #deforestation and hunting pressures. Help them survive #BoycottPalmOil 🌴☠️⛔️ #Boycott4Wildlife @palmoildetect.bsky.social https://palmoildetectives.com/2021/01/31/pig-tailed-snub-nosed-langur-simias-concolor/?utm_source=mastodon&utm_medium=Palm+Oil+Detectives&utm_campaign=publer

@FotoVorschlag tierische freunde

#fotovorschlag #mockfotos #photography #blackandwhite #animals #langur #india

Random photo of the day.

#photography #random #photooftheday #POTD #dailyphoto #OttawaPhotographer #nature #wildlife #langur #eastjavanlangur #primate #zoo #closeup #BronxZoo

Pig-tailed Snub-nosed Langur Simias concolor

Pig-tailed Snub-nosed Langur Simias concolor

IUCN Red List Status: Critically Endangered

Location: This rare primate is endemic to the Mentawai Islands off the west coast of Sumatra, Indonesia. They are found on Siberut, Sipora, and North and South Pagai, where they inhabit lowland and hill forests in these isolated and fragile ecosystems.

The Pig-tailed Snub-nosed Langur, also known as the Pig-tailed Langur, is one of the most distinctive and endangered monkeys in the world. These ultra rare and critically endangered small primates are known for their short, upturned noses and unique pig-like tails. Pig-tailed Snub-nosed Langurs are critically endangered due to palm oil and timber deforestation, hunting, and habitat fragmentation in their tiny island homes of Siberut, Sipora, and North and South Pagai, Indonesia. Immediate conservation action is necessary to protect the remaining population and their delicate ecosystem from disappearing forever. Fight for them every time you shop and #BoycottPalmOil #Boycott4Wildlife

https://youtu.be/JOfOyb0Okys

Forgotten #primate 🙊🐒 Pig-tailed Snub-nosed #Langur is now critically endangered on tiny islands near #Sumatra #Indonesia 🇮🇩 from #palmoil #deforestation and hunting pressures. Help them survive #BoycottPalmOil 🌴☠️⛔️ #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/31/pig-tailed-snub-nosed-langur-simias-concolor/

Pig-tailed Snub-nosed #langurs have a cute upturned nose and a pig-like tail. They’re critically #endangered by #palmoil #deforestation and hunting in #Indonesia 🇮🇩🐒 Resist their #extinction! #BoycottPalmOil 🌴☠️⛔️ #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/31/pig-tailed-snub-nosed-langur-simias-concolor/

Appearance and Behaviour

The Pig-tailed Snub-nosed Langur is a medium-sized primate with a striking appearance. Their dense, greyish-brown fur contrasts with lighter underparts, and their small, upturned nose gives them a unique and endearing look. Their short, thick tail, resembling that of a pig, is another defining feature (IUCN, 2020).

These langurs are diurnal and arboreal, spending most of their time in the forest canopy. They live in social groups of up to 20 individuals, where they engage in complex communication and social bonding. Their dynamic foraging strategies allow them to adapt to the heterogeneous environments of the Mentawai Islands.

This species is listed as Critically Endangered because a population decline of 80-90% over the last 36 years (three generations) is estimated due to heavy hunting pressure and extensive habitat loss (especially on southern islands but quite significant throughout species range). The Pig-tailed Snub-nosed Langur is threatened mainly by heavy hunting and commercial logging (Whittaker 2006, Quinten et al. 2014).

IUCN Red List

Diet

The Pig-tailed Snub-nosed Langur is primarily folivorous, feeding on a variety of leaves, but they also consume fruits, seeds, and flowers when available. This specialised diet ties them closely to their forest environment, making them highly vulnerable to habitat destruction and fragmentation (IUCN, 2020).

Reproduction and Mating

As with many langurs, this species is believed to have a low reproductive rate. Females give birth to a single infant after a long gestation period, and young langurs are raised with the support of the social group. This cooperative behaviour is vital for ensuring the survival of the next generation in their challenging environment.

Geographic Range

The Pig-tailed Snub-nosed Langur is restricted to the Mentawai Islands, including Siberut, Sipora, and North and South Pagai. These islands are home to diverse but fragile ecosystems, where this species relies on primary and secondary forests for survival. Their limited geographic range makes them highly vulnerable to localised threats (IUCN, 2020).

Threats

They are also threatened by the conversion of rainforest into oil palm plantations, as well as forest clearing and product extraction by local people. Sometimes, animals are taken for the pet trade (Whittaker 2006).

IUCN Red LIST

• Palm oil and timber deforestation: The rapid expansion of out-of-control palm oil plantations, logging, and agricultural activities has resulted in the widespread destruction of the Mentawai Islands’ forests.
• Illegal hunting for bushmeat: The langur is heavily hunted for bushmeat, a significant threat in local communities.
• Habitat Fragmentation: Infrastructure development and forest clearing have fragmented their habitats, isolating populations and reducing genetic diversity.

Take Action!

Protecting the Pig-tailed Snub-nosed Langur requires urgent conservation measures to halt deforestation and hunting. By boycotting products containing palm oil, supporting indigenous-led conservation initiatives, and advocating for forest preservation, you can help safeguard this critically endangered primate. #BoycottPalmOil #Boycott4Wildlife #Vegan

Conservation

Conservation efforts for these critically endangered small primates is underway. Read more about Asian Species Action Partnership (ASAP) in Indonesia.

Further Information

Quinten, M, Setiawan, A., Cheyne, S., Traeholt, C. & Whittaker, D. 2020. Simias concolor. The IUCN Red List of Threatened Species 2020: e.T20229A17953422. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T20229A17953422.en. Downloaded on 31 January 2021.

Zhao, L., et al. (2024). Dynamic foraging strategy adaptation to heterogeneous environments contributes to social aggregation in snub-nosed monkeys. Zoological Research, 45(1), 39–54. https://doi.org/10.24272/j.issn.2095-8137.2023.047

Wikipedia. (n.d.). Pig-tailed Langur. Retrieved from https://en.wikipedia.org/wiki/Pig-tailed_langur

GBIF. (n.d.). Simias concolor. Retrieved from https://www.gbif.org/species/4267130

Pig-tailed Snub-nosed Langur Simias concolor

How can I help the #Boycott4Wildlife?

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The World’s Most Loved Cup: A Social, Ethical & Environmental History of Coffee by Aviary Doert

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How do we stop the world’s ecosystems from going into a death spiral? A #SteadyState Economy

Read more

3. Supermarket sleuthing: Next time you’re in the supermarket, take photos of products containing palm oil. Share these to social media along with the hashtags to call out the greenwashing and ecocide of the brands who use palm oil. You can also take photos of palm oil free products and congratulate brands when they go palm oil free.

https://twitter.com/CuriousApe4/status/1526136783557529600?s=20

https://twitter.com/PhillDixon1/status/1749010345555788144?s=20

https://twitter.com/mugabe139/status/1678027567977078784?s=20

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#Boycott4wildlife #BoycottPalmOil #CottonHeadedTamarinSaguinusOedipus #CriticallyEndangeredSpecies #deforestation #endangered #extinction #Indonesia #langur #Langurs #Mammal #palmoil #Primate #Sumatra #vegan

Sabah Grizzled Langur Presbytis sabana

Sabah Grizzled Langur Presbytis sabana

Red List Status: Endangered

Location: Malaysia (Sabah), Indonesia (North Kalimantan)

This elusive primate lives in lowland, riparian, montane, and evergreen forests of northern Borneo, including protected areas such as the Danum Valley, Tabin Reserve, and the Kinabatangan region.

The Sabah Grizzled Langur Presbytis sabana, also known as the Saban Grizzled #Langur or Crested Grizzled Langur, is a strikingly beautiful leaf #monkey found only in #Borneo. Their #Endangered status is a direct result of extensive habitat destruction caused by deforestation, out-of-control palm oil expansion, and #hunting—particularly for bezoar stones used in traditional medicine. With fragmented populations and little known about their behaviour or numbers, urgent action is needed to prevent their extinction. Use your wallet as a weapon. Avoid #palmoil when you shop and demand an end to wildlife trafficking and forest destruction. #BoycottPalmOil #Boycott4Wildlife #Vegan

Sabah Grizzled #Langurs live in the treetops of #Sabah #Malaysia 🐒🐵🇲🇾 Their main threats are #palmoil and #meat agriculture #deforestation. Help to protect these elegant monkeys when you #BoycottPalmOil 🌴🩸🔥☠️🤮🧐🙊⛔️#Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/25/msaban-grizzled-langur-presbytis-sabana/

Appearance and Behaviour

The Sabah Grizzled Langur is a captivating primate with a thick coat of grey, grizzled fur and a pale belly, sharply contrasted by black hands and feet. A pointed crown of fur rises from their head, giving them a distinct, almost regal look. Their spade-shaped, pale-pinkish faces are framed by dark rings around wide, expressive eyes—an appearance that makes them instantly memorable to anyone lucky enough to see one.

These langurs are diurnal and arboreal, spending most of their lives high in the forest canopy. At night, they retreat to the upper branches of emergent trees to sleep, likely as a defence against predators. They are nimble and versatile movers, walking on all fours, leaping, climbing, and even hanging suspended beneath branches. Their daily lives involve foraging, grooming, resting, and socialising in cohesive groups that typically consist of one dominant male and several adult females with their young.

Diet

Sabah Grizzled Langurs are primarily folivores, feeding on a wide range of leaves, young shoots, and unripe seeds. They also eat fruit, flowers, buds, insects, bird eggs, and mineral-rich mud to supplement their diet. Their complex, multi-chambered stomachs ferment leafy material efficiently, allowing them to extract maximum nutrition from tough plant matter.

The diet of the Sabah Grizzled Langur shifts based on the level of forest disturbance. In undisturbed forests, leaves dominate their intake, but in logged areas, they consume more fruit and seeds. This adaptability may be crucial to their survival in fragmented landscapes.

Reproduction and Mating

This species follows a polygynous mating system, with a single adult male having exclusive breeding access to the females in the group. Breeding appears to occur year-round, but births peak between July and October. After a gestation of five to six months, the female gives birth to a single infant.

Infants are born with paler fur that darkens over time. They are weaned at around 11 months and become subadults between 21 and 36 months. Both males and females leave their natal groups upon reaching sexual maturity at about three years of age, either joining new groups or forming their own.

Geographic Range

Sabah Grizzled Langurs are endemic to the island of Borneo and are found only in Sabah (Malaysia) and northern parts of Indonesian Kalimantan. They inhabit evergreen, lowland, montane, and riverine forests, as well as selectively logged areas and tree plantations. Though once considered a subspecies of Presbytis hosei, they are now recognised as a distinct species. Populations are scattered and fragmented, with some surviving in protected areas like Danum Valley and the Maliau Basin, but others are highly vulnerable to extinction.

Threats

• Palm oil deforestation, monoculture expansion and habitat fragmentation

Large-scale clearing of Borneo’s forests for palm oil plantations has severely reduced the habitat of Presbytis sabana. This deforestation not only destroys the canopy cover they rely on for movement and shelter but also creates isolated forest patches that hinder gene flow and increase vulnerability to inbreeding and local extinction. Even selectively logged areas can remove critical roosting trees and food sources, leading to population collapse over time.

• Hunting for their meat and bezoar stones

Local hunting poses a grave threat to this species. Bezoar stones—calcified objects sometimes found in the gastrointestinal tracts of langurs—are falsely believed to have medicinal properties and fetch high prices in illegal markets. As a result, these langurs are hunted both for meat and for supposed curative use, putting intense pressure on already dwindling populations.

• Lack of enforcement in protected areas

While some populations live in conservation zones, many of these are inadequately protected. Illegal logging, poaching, and encroachment continue within the boundaries of national parks and reserves. Without sufficient monitoring, resources, and community involvement, these areas offer little real safety for the langurs.

• Low reproductive rate and slow population recovery

Like many primates, Sabah Grizzled Langurs have slow reproductive cycles, giving birth to a single infant every one to two years. This low birth rate means that even small increases in mortality can cause long-term population declines. Combined with hunting and habitat loss, this makes recovery especially difficult without urgent conservation action.

Take Action!

The fate of the Sabah Grizzled Langur is partially tied to our consumer choices. Avoid products that contain palm oil, especially those contributing to Bornean deforestation. Never support the exotic animal trade or products made from endangered species. Support indigenous-led conservation efforts and protect Southeast Asia’s remaining rainforests. #BoycottPalmOil #Boycott4Wildlife #Vegan #BoycottMeat

FAQs

How many Sabah Grizzled Langurs are left?

Exact population numbers are unknown due to a lack of comprehensive surveys, but the IUCN lists them as Endangered and rapidly declining. Fragmentation of their range and localised hunting make many populations highly vulnerable, and some may already be functionally extinct.

What is the lifespan of Presbytis sabana?

While the exact lifespan of Presbytis sabana is not documented, related langurs typically live around 20–25 years in the wild. Infant mortality may be high in disturbed habitats, especially where hunting pressure is intense.

Why are bezoar stones a threat?

Bezoar stones are hard masses found in the intestines of some langurs, falsely believed to have healing powers in traditional medicine. This belief drives illegal hunting, even though scientific evidence shows these stones have no proven medical value. Killing langurs for this purpose is both cruel and contributes directly to their extinction.

How are Sabah Grizzled Langurs affected by palm oil?

Palm oil plantations are a major cause of deforestation in Borneo. These plantations clear vast areas of native forest, severing the canopy corridors that langurs use to travel. Even plantations that claim to be ‘eco-friendly’ contribute to ecosystem collapse by fragmenting habitat and displacing wildlife.

Do Sabah Grizzled Langurs make good pets?

No. These langurs are not suited to captivity and have not been documented in zoos or pet markets. Their specialised diet and social needs cannot be met outside the wild. Keeping langurs as pets is illegal, unethical, and further threatens their survival.

Support the conservation of this species

This animal has no protections in place. Read about other forgotten species here. Create art to support this forgotten animal or raise awareness about them by sharing this post and using the #Boycottpalmoil #Boycott4Wildlife hashtags on social media. Also you can boycott palm oil in the supermarket.

Further Information

Nijman, V. (2017). Group composition and monandry in grizzled langurs, Presbytis comata, on Java. Folia Primatologica, 88(2), 237–254. https://doi.org/10.1159/000478695

Ramlee, H. (2013). Distribution, ecology and systematics of Presbytis hosei and other leaf monkey species in North Borneo [PhD thesis, Australian National University]. Open Research Repository. https://openresearch-repository.anu.edu.au/items/26fbc1b7-b536-427c-a8d2-62984e69b43e

Setiawan, A. & Traeholt, C. 2020. Presbytis sabana. The IUCN Red List of Threatened Species 2020: e.T39810A17987041. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T39810A17987041.en. Downloaded on 25 January 2021.

Wikipedia contributors. (n.d.). Sabah grizzled langur. Wikipedia. Retrieved from https://en.wikipedia.org/wiki/Sabah_grizzled_langur

Sabah Grizzled Langur Presbytis sabana

How can I help the #Boycott4Wildlife?

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Wildlife Artist Juanchi Pérez

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Anthropologist and Author Dr Sophie Chao

Read more

Health Physician Dr Evan Allen

Read more

The World’s Most Loved Cup: A Social, Ethical & Environmental History of Coffee by Aviary Doert

Read more

How do we stop the world’s ecosystems from going into a death spiral? A #SteadyState Economy

Read more

3. Supermarket sleuthing: Next time you’re in the supermarket, take photos of products containing palm oil. Share these to social media along with the hashtags to call out the greenwashing and ecocide of the brands who use palm oil. You can also take photos of palm oil free products and congratulate brands when they go palm oil free.

https://twitter.com/CuriousApe4/status/1526136783557529600?s=20

https://twitter.com/PhillDixon1/status/1749010345555788144?s=20

https://twitter.com/mugabe139/status/1678027567977078784?s=20

4. Take to the streets: Get in touch with Palm Oil Detectives to find out more.

5. Donate: Make a one-off or monthly donation to Palm Oil Detectives as a way of saying thank you and to help pay for ongoing running costs of the website and social media campaigns. Donate here

#Agriculture #Bornean #Borneo #Boycott4wildlife #BoycottMeat #BoycottPalmOil #deforestation #endangered #EndangeredSpecies #ForgottenAnimals #hunting #Indonesia #Kalimantan #langur #Langurs #Malaysia #Mammal #meat #monkey #palmoil #poachers #poaching #Primate #Sabah #SabahGrizzledLangurPresbytisSabana #SouthEastAsia #vegan

Bornean Banded Langur Presbytis chrysomelas

Bornean Banded Langur Presbytis chrysomelas

Critically Endangered

Brunei; Indonesia (Kalimantan); Malaysia (Sarawak)

The Bornean banded langur, known for its striking black and white coat, is one of Southeast Asia’s most elusive and endangered primates. These langurs inhabit the fragmented lowland forests and peat swamps of Borneo, relying on dense foliage for their survival.

The population of Bornean banded langurs is rapidly declining due to habitat destruction for palm oil plantations, illegal logging, and hunting. As their habitat continues to shrink, these shy and rarely seen primates face an uncertain future. Use your wallet as a weapon—boycott palm oil and join the fight for their survival. #BoycottPalmOil #Boycott4Wildlife

Bornean Banded Langurs 🐒🤎🙊 are critically #endangered in #Indonesia 🇮🇩 #Malaysia 🇲🇾 as 80% of their rainforest home was destroyed in past 30 years for #palmoil. Tell brands enough is enough! #BoycottPalmOil 🌴🪔🤢🤮⛔️ #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/24/bornean-banded-langur-presbytis-chrysomelas/

Once common, now crit. endangered, the Bornean Banded #Langur hangs on for dear life in small patches of #rainforest in #Indonesia 🇮🇩 #Malaysia 🇲🇾. 80% of their home was destroyed for #palmoil. #BoycottPalmOil 🌴🪔🤢🤮⛔️ #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/24/bornean-banded-langur-presbytis-chrysomelas/

This species of Langur is listed as Critically Endangered as it is only known from five sites, where populations have been reduced by approximately 80% over the past 30 years (three generations) and the trend is suspected to continue into the future due to habitat loss from expanding oil palm cultivation.

IUCN Red List

In addition, the area of occupancy has been reduced dramatically. This species was once considered common. They are now considered one of the rarest primates in the world. They live in less than 5% of their historic range. Additional conservation measures are urgent as this species could go extinct if current trends continue.

Appearance and Behaviour

Bornean banded langurs are medium-sized monkeys, reaching about 50–60 cm in body length with a long, slender tail often exceeding their body length. They are distinguished by their unique black and white banded coat, which provides excellent camouflage among tree branches. Their expressive faces, encircled by pale fur, give them an inquisitive and alert appearance.

Primarily arboreal and diurnal, they spend most of their time in the upper forest canopy, where they live in small groups of 3–10 individuals. Group dynamics often include a dominant male, several females, and their offspring. Bornean banded langurs are highly social and communicate using a range of vocalisations, including soft grunts and alarm calls when sensing danger.

Geographic Range

These langurs are endemic to Borneo and are found in Malaysia’s Sabah and Sarawak regions as well as Indonesia’s Kalimantan. Their preferred habitats include lowland dipterocarp forests, peat swamps, and mangroves. However, habitat destruction has fragmented their range, leaving populations isolated in areas such as Danau Sentarum National Park and Tanjung Datu National Park (IUCN, 2020).

Diet

Bornean banded langurs are folivorous, primarily feeding on young leaves, flowers, seeds, and unripe fruits. Their specialised stomachs are adapted to digest fibrous plant material efficiently, enabling them to extract maximum nutrients from their diet. This diet also plays a vital role in seed dispersal, contributing to forest regeneration and biodiversity (NePrimate Conservancy, 2024).

Reproduction and Mating

These langurs exhibit a slow reproductive cycle. Females typically give birth to a single infant every 1–2 years after a gestation period of about 6 months. Infants are born with bright orange coats, which gradually transition to the adult black and white coloration as they mature.

Mothers provide extensive care, with other group members occasionally assisting in grooming or protecting the young. This communal care highlights their highly social nature. However, the slow reproductive rate makes it difficult for the species to recover from population declines.

Threats

The Bornean banded langur is listed as Critically Endangered by the IUCN, with populations continuing to decline. Conservation efforts focus on habitat restoration and protection in key national parks such as Danau Sentarum and Tanjung Datu. Organisations are also working to combat illegal logging and raise awareness about the impact of palm oil.

IUCN Status: Critically Endangered

• Palm oil and timber deforestation: Deforestation for palm oil plantations and logging has decimated much of their forest habitat. Between 2000 and 2018, more than 30% of suitable habitat was lost across Borneo.
• Hunting and poaching: Although not commonly targeted, these langurs are occasionally hunted for bushmeat or captured for the exotic pet trade.
• Habitat fragmentation: Habitat fragmentation isolates populations, reducing genetic diversity and increasing the risk of local extinction.
• Climate Change: Rising temperatures and changes in rainfall patterns threaten the health of their forest ecosystems.

Take Action!

Protect the Bornean banded langur by boycotting palm oil and supporting conservation programs focused on preserving Borneo’s forests. Raise awareness about their plight and advocate for stronger legal protections. Together, we can secure a future for these remarkable primates. #BoycottPalmOil #Boycott4Wildlife

You can support this beautiful animal

There are no known conservation activities for this animal. Share out this post to social media and join the #BoycottPalmOil #Boycott4Wildlife on social media to raise awareness

Further Information

Md-Zain, B. M. (2019). Bornean banded langur in Danau Sentarum National Park.

NePrimate Conservancy. (2024). Bornean banded langur (Presbytis chrysomelas).

Nijman, V., Cheyne, S., Traeholt, C. & Setiawan, A. 2020. Presbytis chrysomelas. The IUCN Red List of Threatened Species 2020: e.T39803A17955321. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T39803A17955321.en. Downloaded on 24 January 2021.

Phillipps, Q., & Phillipps, K. (2019). Presbytis chrysomelas population survey in Borneo.

Rustam, A., & Yanuar, A. (2021). Preliminary assessment of group composition and activity pattern of the critically endangered Bornean banded langur (Presbytis chrysomelas) in Tanjung Datu National Park.

Tanjung, H., et al. (2024). Impacts of habitat loss on Presbytis chrysomelas populations.

Bornean Banded Langur Presbytis chrysomelas

How can I help the #Boycott4Wildlife?

Take Action in Five Ways

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Wildlife Artist Juanchi Pérez

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Anthropologist and Author Dr Sophie Chao

Read more

Health Physician Dr Evan Allen

Read more

The World’s Most Loved Cup: A Social, Ethical & Environmental History of Coffee by Aviary Doert

Read more

How do we stop the world’s ecosystems from going into a death spiral? A #SteadyState Economy

Read more

3. Supermarket sleuthing: Next time you’re in the supermarket, take photos of products containing palm oil. Share these to social media along with the hashtags to call out the greenwashing and ecocide of the brands who use palm oil. You can also take photos of palm oil free products and congratulate brands when they go palm oil free.

https://twitter.com/CuriousApe4/status/1526136783557529600?s=20

https://twitter.com/PhillDixon1/status/1749010345555788144?s=20

https://twitter.com/mugabe139/status/1678027567977078784?s=20

4. Take to the streets: Get in touch with Palm Oil Detectives to find out more.

5. Donate: Make a one-off or monthly donation to Palm Oil Detectives as a way of saying thank you and to help pay for ongoing running costs of the website and social media campaigns. Donate here

#BorneanBandedLangurPresbytisChrysomelas #Borneo #Boycott4wildlife #BoycottPalmOil #Brunei #CriticallyEndangeredSpecies #endangered #Indonesia #Kalimantan #langur #Malaysia #Mammal #palmoil #Primate #rainforest #SeedDispersers #SouthEastAsia

Thomas’s Langur Presbytis thomasi

Thomas’s Langur Presbytis thomasi

IUCN Status: Vulnerable (VU)

Location: Indonesia – Sumatra (Aceh Province)

Thomas’s Langur, also known as the North Sumatran Leaf #Monkey is famous for their bold facial stripes giving them a handsome profile. These monkeys are endemic to the lush forests of northern Sumatra, Indonesia. Listed as Vulnerable by the Red List, this striking species is facing serious population declines due to habitat loss, primarily driven by illegal logging and oil palm deforestation. Though not as globally known as some of its neighbours, such as the Sumatran Orangutan, Thomas’s Langur plays an equally vital role in forest regeneration and seed dispersal. You can help protect them by using your consumer power: always choose palm oil-free products.#BoycottPalmOil #Boycott4Wildlife #Vegan

https://youtu.be/kgSJha79_ew

The Thomas’s #Langur has striking stripes 🐵🐒🤎 They’re #vulnerable due to forest clearance for #palmoil and #timber in #Sumatra #Indonesia 🇮🇩 Protect this rare #monkey when you shop and #BoycottPalmOil 🌴🪔☠️🩸🤮🙊🚫 #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/24/thomass-langur-presbytis-thomasi/

Sporting bold facial stripes, the Thomas’s #Langur is a handsome icon of #Sumatra #Indonesia 🇮🇩 Threats include #palmoil #deforestation and human persecution 🏹😿 Fight for their survival and #BoycottPalmOil 🌴🪔☠️🩸🤮🙊🚫 #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2021/01/24/thomass-langur-presbytis-thomasi/

Appearance and Behaviour

Thomas’s Langur is a small-bodied, highly distinctive primate. Their expressive amber eyes are framed by a whimsical ‘mohawk’ of fur – white at the front and dark grey along the midline – with flaring white cheek tufts giving them a perpetual look of surprise. Their back and limbs are grey, while the underparts are pure white, creating a dramatic contrast. Infants are born almost entirely white.

They live in social groups of 10–20 individuals and are arboreal, moving gracefully through the canopy. Though they are agile and peaceful, these monkeys are alert and cautious, especially in areas with higher predator or infanticide risk. They’ve been observed adjusting their vigilance levels depending on their location within the forest and the presence of neighbouring groups.

Diet

Thomas’s Langur is primarily folivorous, meaning their diet mainly consists of leaves. However, they also consume unripe fruit, flowers, toadstools, snails, and even rubber tree seeds when available. They have highly adapted digestive systems with gut microbes capable of breaking down cellulose, allowing them to extract nutrients from fibrous plant material. They tend to avoid ripe fruit, which could kill these microbes, and instead prefer high-pH, less acidic produce.

Reproduction and Mating

These langurs reach reproductive maturity around 5.4 years of age. The average interbirth interval is about 22 months, though this can vary depending on whether the previous infant survives. Females give birth to a single offspring at a time and care for them extensively. Infanticide by incoming males is a documented threat in overlapping territories, which may influence both vigilance and social dynamics within groups.

In the wild, Thomas’s Langurs live up to 20 years, with longevity extending to 29 years in captivity due to the absence of predators and reduced stress.

Geographic Range

Thomas’s Langur is restricted to northern Sumatra in Indonesia, primarily within Aceh Province. They are found north of the Alas (Simpangkiri) and Wampu Rivers, though newer records suggest they also exist just south of the Alas. Key populations reside in the Leuser Ecosystem, particularly around the Ketambe Research Station and Bukit Lawang in Gunung Leuser National Park. The species’ range is geographically fragmented by rivers and human activity.

Threats

The species is considered Vulnerable due to past and continued population declines, estimated at more that 30% over the past 40 years (three generations) due to loss of habitat, especially to logging and oil palm plantations. Due to continuing threats, it is suspected to decline at the same rate over the next one generation.

IUCN Red List

• Palm oil and timber deforestation

Thomas’s langur faces severe habitat loss due to widespread deforestation in northern Sumatra. Logging operations, both legal and illegal, have cleared vast tracts of primary forest, fragmenting the langurs’ habitat and forcing them into smaller, isolated patches. The conversion of forests into oil palm plantations is accelerating this destruction, leading to population declines estimated at more than 30% over the past 40 years. This fragmentation not only reduces available food sources but also isolates groups, limiting genetic diversity and increasing the risk of local extinctions.

• Hunting and human persecution

Though protected by the local Batak traditional and religious taboos, there is some ‘marginal’ hunting pressure in the other parts of their distribution. The species is sometimes killed for bushmeat or captured for traditional medicine practices. In areas where these taboos are not observed, or where poverty drives people to seek alternative food sources, hunting pressure remains a real threat. Even low levels of hunting can have significant impacts on slow-reproducing primates like Thomas’s langur.

• Illegal Pet Trade

Infant langurs are often captured and sold in wildlife markets, especially in areas close to tourism hotspots like Bukit Lawang. To obtain a baby, adult females are usually killed, which has devastating consequences for troop dynamics and survival. Captive langurs often suffer from malnutrition, stress, and poor care, and rarely survive long in the pet trade. This exploitation is driving the species further toward extinction and contributes to the destruction of wild populations.

• Human-Wildlife Conflict

As forests are cleared, Thomas’s langurs increasingly move into croplands and plantations in search of food. This brings them into direct conflict with farmers, who may perceive them as pests and shoot them to protect crops. These retaliatory killings are not only cruel but contribute to the already rapid decline in population numbers. Furthermore, such conflicts reduce public tolerance for the species and hinder conservation efforts unless addressed through community engagement and education.

Take Action!

Thomas’s Langur is a symbol of Sumatra’s disappearing biodiversity. Protecting their habitat means preserving the rich web of life in which they play an essential role. You can make a difference, every time you shop #BoycottPalmOil #Boycott4Wildlife. Advocate for indigenous-led conservation in Sumatra and campaign against the illegal wildlife trade. Support plant-based agriculture and rewilding efforts. Go #Vegan #BoycottMeat

FAQs

How many Thomas’s Langurs are left in the wild?

Exact population estimates for the Thomas’s Langur are unknown, but data suggests that their numbers have declined by more than 30% in the past 40 years (three generations). This is largely due to habitat destruction and fragmentation (Wich et al., 2007).

How long do Thomas’s Langurs live?

In the wild, they typically live around 20 years. In captivity, individuals have been known to live up to 29 years (Wich et al., 2007).

Why are Thomas’s Langurs endangered?

The main threat is deforestation from logging and conversion of land into palm oil plantations. This leads to loss of their primary rainforest habitat and forces them into closer contact with humans, where they may be shot or captured for trade (IUCN, 2021).

Do Thomas’s Langurs make good pets?

Absolutely not. Keeping Thomas’s Langurs as pets is not only unethical but illegal. The illegal pet trade contributes directly to their decline, as infants are taken from their mothers, often involving violence. Supporting this trade fuels cruelty and threatens their survival. Advocate against the exotic pet trade instead.

Further Information

Setiawan, A. & Traeholt, C. 2020. Presbytis thomasi. The IUCN Red List of Threatened Species 2020: e.T18132A17954139. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T18132A17954139.en. Downloaded on 24 January 2021.

Ecology Asia. (n.d.). Thomas’s Leaf Monkey – Presbytis thomasi. Retrieved March 25, 2025, from https://www.ecologyasia.com/verts/mammals/thomas’s-leaf-monkey.htm

Sterck, E. H. M., Willems, E. P., van Schaik, C. P., & Wich, S. A. (2005). Demography and life history of Thomas langurs (Presbytis thomasi). American Journal of Primatology, 69(6), 641–651. https://doi.org/10.1002/ajp.20386

Steenbeek, R., Piek, R. C., van Buul, M., & van Hooff, J. A. R. A. M. (1999). Vigilance in wild Thomas’s langurs (Presbytis thomasi): the importance of infanticide risk. Behavioral Ecology and Sociobiology, 45, 137–150. https://doi.org/10.1007/s002650050547

Wich, S. A., Steenbeek, R., Sterck, E. H. M., Korstjens, A. H., Willems, E. P., & van Schaik, C. P. (2007). Demography and life history of Thomas langurs (Presbytis thomasi). American Journal of Primatology, 69(6), 641–651. https://doi.org/10.1002/ajp.20386

Wich, S. A., Schel, A. M., de Vries, H., & van Schaik, C. P. (2008). Geographic variation in Thomas Langur (Presbytis thomasi) loud calls. American Journal of Primatology, 70(6), 566–574. https://onlinelibrary.wiley.com/doi/10.1002/ajp.20527

Wikipedia contributors. (n.d.). Thomas’s langur. Wikipedia. Retrieved March 25, 2025, from https://en.wikipedia.org/wiki/Thomas%27s_langur

Thomas’s Langur Presbytis thomasi

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“To see in color is a delight for the eye but to see in black and white is a delight for the soul” – Andri Cauldwell

This is a Grey Langur shot a couple of years back at Bandhavgarh. What really caught my attention when I looked through the viewfinder were his eyes. There is something quite arresting about his gaze - seems almost as if he is lost in his thoughts.

#photo #photography #wildlife #langur #blackandwhite

"Colour is descriptive. Black and white is interpretive.” – Eliott Erwitt

This is a Grey Langur shot a couple of years back at Bandhavgarh. What really caught my attention when I looked through the viewfinder were his eyes. There is something quite arresting about his gaze - almost as if he is lost in his thoughts.

#photo #photography #wildlife #langur