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Vietnam's Disappearing Douc Langurs

Living on the edge of existence Vietnam’s primate species are in serious danger. The country boasts a wide variety of different primate species, each fitting to their unique habitats. Unfortunately all of these species are under serious pressure from another primate species, humans.

In my previous article we looked at the conservation issues of the Delacour Langur (Trachypithecus delacouri). One of Vietnam's 4 langur species that are perfectly adapted for life in limestone landscapes. The other 3 species of langur occupy rainforest habitat, leading to different appearance and behaviours. In this article we will look at the issues involved in these rainforest langur species.

Douc Langurs are among the most beautiful and endangered primates in the world. They are only found in three countries in the world: Vietnam, Cambodia and Laos. Like so many primates worldwide poaching, trapping and illegal trade are threatening their survival in all three countries. There are three species of Douc Langur, the red-shanked (Pygathrix nemaeus), black-shanked (Pygathrix nigripes) and grey-shanked (Pygathrix cinereus) each occupying different geographical areas across Indochina.

The Red Shanked Douc can be found in Northcentral Vietnam, Central and Southern Laos, and Northeastern Cambodia. This species is distinguished by its bright maroon/red “stockings” which run from its knees to its ankles. Diurnal and arboreal, they travel through the canopy feeding predominantly on leaves. They mostly live in family groups of one single male and multi females, but can come together into larger groups of up to 50 animals in a fission-fusion association. The species is listed as Critically Endangered.

Following on, the Grey Shank Douc occurs in Central Vietnam and was more recently discovered to also occur in Southeastern Lao and Northeastern Cambodia. The population is estimated at no more than 1000 individuals in Vietnam. The key difference from the Red Shanked Douc is the grey to black legs, instead of the red colour. These langurs can be found living in four different social groupings, one male and multiple females, all male, solitary males, and large multi-male and multi-female groupings. The grey shank is also listed as critically endangered.

Finally, the Black Shanked Douc occurs in Southern Vietnam and Eastern Cambodia. I was lucky enough to encounter a family of these at Cat Tien National Park. The population is extremely fragmented and a good estimation on size is not available. The arms are grey to black and hands, feet and legs are black. Unlike the other two species which have a kind of pale red face, the Black Shank has a pale blue face colouration. They share similar social grouping patterns of the Red Shanked Douc, also living arboreally and living a diurnal lifestyle. Despite a lack of knowledge on population size this species is only listed as Endangered, not to a critical level, but this may be updated.

It is an amazing example of the wonders of evolution at work, in such a small geographical area there are three similar but still distinct species, living in geographical isolation. Unfortunately though, humans are putting major stress on all three species.

Perhaps the biggest pressure is that of hunting. Douc Langurs are hunted for food, for use in traditional medicine and for sale as pets. Hunting occurs even in protected areas with all primate species being targeted with snare and net traps. Adult body parts are used in traditional medicines and their babies are sold either as pets or illegally to zoos across Asia.

Another threat to not just the langurs but all of Vietnam’s wildlife is toxic poising from the Vietnam War. Between 1965 and 1971 the US government sprayed more than 45 million litres of dioxin- containing herbicides on the forests and hamlets of central and southern Vietnam destroying approximately 10% of forests in that region and leaving many more contaminated.

The destruction of Vietnam’s forests did not stop there. Forest exploitation for a number of uses (including firewood, resins, palm leaves, cycad and rattan) degrades important habitats. Agricultural forest clearing around national park’s increases fragmentation between populations and increases the risk of inbreeding depression, by blocking any possibility of gene flow between the species.

Unfortunately many protected areas are under-staffed and staff are under-equipped, limiting protection they can give to forest species. In Vietnam, enforcement of protective laws rarely occurs, laws aimed at protecting species are not effectively enforced. As well as this literally millions of people live within protected areas in Vietnam, meaning monitoring their behaviour is extremely difficult.

Much like the Delacour Langur, the Doucs are in serious trouble, currently losing the fight against human prosecution. However, the people at Vietnams Endangered Primate Rescue Centre (EPRC) are doing their best to rescue any animals caught in trade. They are also actively trying to breed more langurs in order to release them back into suitable habitats.

However, managing captive populations is not enough. In order to conserve Vietnam’s species, the habitats in which they live must be better protected. This protection must be headed by the government but also taken on board by the individuals involved on the ground, implementing stricter regulations in and around national parks.

The story of Vietnam's Langur species is a tragic one. However, it is not an exclusive one. Our planet is currently facing one of the biggest mass extinctions ever recorded. We are losing species at a ridiculous rate. And this is all happening because of us humans. We are destroying the world’s natural habitats and resources and in turn are destroying our planets natural biodiversity, species from all corners of the world are in need of desperate help. The time to change is now, before it is too late and these species are put into the history books.

Footnote: If you would like to learn more about the work EPRC are doing or even donate money to help them continue their great work then you can follow this link:

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