Greater Mekong primates struggle to hold on amid lingering threats: report

  • The Greater Mekong region is home to 44 species of non-human primates, including gibbons, lorises, langurs, macaques and snub-nosed monkeys, several of which have been described for the first time in recent years.
  • Habitat loss and hunting driven by wildlife trade and consumption have driven many of the region’s primates to the brink of extinction, with many species now existing only as tiny populations in pockets isolated and fragmented habitats.
  • Experts say controlling the illegal wildlife trade is complicated by the presence of legal markets for primates, often used in biomedical research.
  • Despite the challenges, local-level conservation action is delivering results for some primate species in the region while improving livelihoods and ecosystem services for local communities.

When scientists described the Popa langur (Trachypithecus popa) as a species new to science in 2020, it was already staring extinction in the face. Fewer than 260 of the fluffy gray leaf-eating monkeys are estimated to remain in four precariously isolated patches of forest in the central plains of Myanmar, where their survival is threatened by habitat loss and hunting.

And the Popa langur is not alone in its fate. Some 90% of non-human primate species in the Greater Mekong region are listed as endangered (vulnerable, endangered or critically endangered) on the IUCN Red List, according to a report released earlier. this month by the WWF.

Deforestation, habitat degradation and hunting to supply the wildlife trade have driven many of the region’s gibbons, lorises, langurs, macaques and snub-nosed monkeys to the brink of extinction, the report says. It incorporates the latest updates to IUCN species assessments, in which a quarter of the region’s primate species have been relegated to a higher threat category.

A camera trap captures a Popa langur (Trachypithecus popa) in the central plains of Myanmar. Its facial markings are distinct from its closest relative, the Phayre langur. Photo courtesy of WWF Myanmar

Of the 44 primate species in the Greater Mekong region, which spans Cambodia, Laos, Myanmar, Thailand and Vietnam, 12 are considered critically endangered. The world population of some endemic species is tiny: for example, less than 100 snub-nosed monkeys from Tonkin (Rhinopithecus avunculus) exist, exclusively in a small patch of limestone karst forest in Vietnam; and a surviving population of no more than 140 Cao-Vit black-crested gibbons (Nomascus nasutus) clings to a strand of forest on the Sino-Vietnamese border.

Meanwhile, about half of the species are endangered, including skywalker hoolock gibbons (Hoolock tianxing), a species that was only described in 2017 from eastern Myanmar and southwestern China, and pygmy slow lorises (Nycticebus pygmaeus), which are captured and traded as pets or killed for use in traditional medicine.

Primates are also exposed to human pathogens, like the coronavirus, which can be transmitted from humans to animals, the report says, a threat that increases as habitats degrade and become more fragmented, forcing humans and wildlife to to get closer.

Gibbon hoolock Skywalker
An endangered hoolock skywalker gibbon (Hoolock tianxing), a species first described in 2017, photographed in Yunnan Province, China. Photo courtesy of Magnus Lundgren/Wild Wonders of China/WWF

Trade lacks oversight

While most primates follow an arboreal lifestyle, allowing them to avoid the millions of traps that litter the region’s forests at ground level, many species are still under heavy hunting pressure, according to Yoganand Kandasamy, chief Wildlife and Wildlife Crime Area at WWF Greater Mekong and co-author of the WWF report. This results in an “empty forest syndrome”, in which protected areas and forests exist, but are devoid of animals.

The motives for hunting range from the live capture of gibbons and lorises for tourism and the pet trade, to slaughter for food at a subsistence level, and to harvest body parts for use in the traditional medicines.

Along with habitat loss, the wildlife trade – both legal and illegal – poses a serious threat to primates in the Greater Mekong: a 2017 study found that between 2005 and 2014, more than 450,000 primates been traded worldwide, with Asian species accounting for 93% of the trade.

A high proportion of trade in the region is domestic, the report says, but the lack of formal oversight and regulation and a growing proportion of online transactions are hampering attempts by experts to assess legality and impacts on wild populations.

“Those concerned are primarily focused on international trade governed by CITES” – the international convention to ensure that wildlife trade does not lead to the extinction of species – “but trade within national borders is a huge and overlooked threat because we don’t have access to the data there, we don’t know how intense it is, and there are no national databases available,” Yoganand said.

Additionally, there is a burgeoning legal trade in captive-bred primates for biomedical, toxicological, and pharmaceutical research. In the Greater Mekong region, long-tailed macaque “farms” in Cambodia, Laos and Vietnam export thousands of animals each year to research centers in regions such as China, Europe, Japan and the United States.

Although much of this international trade is documented by CITES and may appear legitimate at first glance, “there are potentially huge illegalities, threats and risks associated with it,” according to Yoganand. In particular, legal trade impacts wild populations as weak law enforcement and transparency allow traffickers to pass off wild-caught animals as captive-bred animals.

“Legal trade doesn’t mean it’s sustainable, it doesn’t mean it’s ethical, it doesn’t mean it takes care of animal welfare or takes into account the risk of disease transmission,” he said. said Yoganand, adding that the regulatory gray areas that continue to facilitate the exploitation of wild animals need to be clarified. “There are still many shortcomings that need to be addressed, including monitoring protocols, independent checks, ensuring there is no money laundering, better enforcement and credible non-harmful findings.”

Lao Langur
An endangered Lao Langur (Trachypithecus laotum), held in a facility in Lak Sao near the Vietnamese border. Photo courtesy of WWF-Greater Mekong

Targeted action

Yoganand said action at the local level has huge potential to reverse the trajectory of many species in the region. The fact that some species are highly restricted means conservation efforts can be focused, local communities can be engaged and limited budgets can go further, Yoganand said. “There have been some very good stories of working with local communities and successful conservation – the primates are benefiting and the local communities are benefiting as well.”

For Paul Garber, a primatologist at the University of Illinois at Urbana-Champaign, the alarming global decline in primate numbers is a wake-up call. When Garber and his colleagues published a review of the world’s primates in 2017, 60% of species were threatened with extinction. “Now, just five years later, that figure has risen to around 66%, and I would say that is still an underestimate; many species are missing data,” he told Mongabay in a recent interview.

Garber said corporations, governments and buyers in wealthy consumer countries must take responsibility for their complicity in the devastating conversion of natural habitats around the world that drives biodiversity loss.

As our closest living relatives, primates offer critical information about human evolution, biology, behavior and emerging diseases, Garber said. They also play a crucial role in maintaining the health of rainforests through pollination and seed dispersal and as prey for top predators. Since they are among the first groups of animals to become extinct when ecosystems become out of balance, they also serve as important indicators of overall ecosystem health.

As Garber describes it, primates “are the canary in the coal mine.” As we continue to degrade, pollute and destroy natural habitats, we will lose primates in the short term, but over time these ecosystems will also become unusable for humans. “Primates foreshadow what will happen to us if we don’t change what we do,” he said.

Banner image: A gibbon photographed in the Dawna Tenasserim forest landscape between Thailand and Myanmar. Photo courtesy of Christy Williams/WWF Myanmar


Estrada, A., Garber, PA, Rylands, AB, Roos, C., Fernandez-Duque, E., Di Fiore, A., … Li, B. (2017). World’s impending primate extinction crisis: why primates matter. Scientists progress, 3(1). doi:10.1126/sciadv.1600946

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Animals, Biodiversity, Biodiversity Crisis, Captive Breeding, Cites, Conservation, Critically Endangered Species, Deforestation, Endangered Species, Environment, Environmental Law, Extinction, Forest Fragmentation, Forests, Fragmentation, Gibbons, Governance, Green, Hunting, Monkeys, Pet Trade, Primates, Traditional Chinese Medicine, Traditional Medicine, Wildlife, Wildlife Crime, Wildlife Trade, Wildlife Trafficking

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