World's second largest population of rare langurs threatened by limestone mining

Around 60 kilometers south of downtown Hanoi, Kim Bang forest in northern Ha Nam Province, covering nearly 4,500 hectares, is home to 13 troops of Delacour's langurs, scientifically named trachypithecus delacouri with 105 individuals.

It it the world’s second largest population of Delacour's langurs, only after one at Van Long Nature Reserve in neighboring Ninh Binh Province, according to non-profit Fauna & Flora International (FFI) Vietnam.

But their natural habitat is being threatened by limestone mining, putting them at risk of extinction.

On a road leading to the forest in Thanh Son Commune, large trucks transport stones to and fro daily, covering the area in a permanent dust cloud. Surrounding this forest are 11 mining sites serving cement and construction material production.

Vietnam is a rapidly emerging industrialized nation, bolstered by the cement industry active in the Kim Bang limestone forest. This relatively small limestone karst outcrop covered in lush foliage is surrounded by dozens of limestone quarries used for cement production.

Inside the forest one warning sign states "Blasting Area, Travel Limited," with many green areas damaged by mining activities.

One winter morning in late 2020, a troop of 12 langurs exited their cave to forage for food.

Adults typically weigh about eight to nine kilograms, have black crests on the top of their heads, white streaked cheeks, and long white hair that resemble short black tails.

Eating for more than an hour, the troop scaled a banyan tree to heat up in the sun and delouse. From a nearby mountain, a harsh whistle indicated a blast was about to occur.

A series of explosions shook the mountain, startling the langurs and sending them scurrying back into the forest.

At the time, Duong Van Son, 33, a member of a community conservation team in Kim Bang forest, used his binoculars to observe the troop beating a retreat.

"They (langurs) appear less and less often as this area is being exploited by stone mining. I don't know where the langurs would go," Son sighed.

Duong Van Son (L) uses binoculars to observe a troop of Delacour's langurs in Ha Nam Province, December 21, 2020. Photo by VnExpress/Tat Dinh.

Growing up in this forest, Son said 15 years ago, when quarries had yet to sprout, the langurs usually foraged along the edge of the forest. Their numbers sometimes reached into the hundreds, but due to disappearing habitat, food scarcity and illegal hunting, the troops have thinned out.

Four years ago, the local community conservation team was established with six members thanks to FFI sponsorship. Its main work is to monitor forest destruction and Delacour's langur population.

"Our lack of numbers and the vast terrain makes it difficult to control illegal hunting," said Son.

"Mining has seriously affected the Kim Bang forest where many langurs live," said a representative of FFI, warning that nine troops are at risk of disappearance.

According to a report by the Ha Nam's Department of Agriculture and Rural Development, there are currently 24 quarrying companies in Lien Son and Thanh Son communes.

Ngo Manh Ngoc, deputy director of the department, said since 2017, it has submitted a proposal to establish a habitat conservation area in the Kim Bang forest, with priority given to Delacour's langurs, but with little result.

Last year, Prime Minister Nguyen Xuan Phuc asked provincial authorities to protect this primate and review the environmental impact of stone mining on the langurs’ natural habitat.

Severely threatened by hunting and limestone quarrying, Delacour’s langur is in urgent need of conservation intervention. FFI is working closely with government agencies and other local partners to halt cement mining that poses a clear and present danger to the karst limestone habitat on which the species depends for survival.

It is estimated that there are about 250 Delacour's langurs to be found in nature, mostly in forest areas in Kim Bang District of Ha Nam and Van Long Wetland in nearby Ninh Binh Province.

The Delacour’s langur is a primate indigenous to Vietnam, first discovered by and named after Jean Théodore Delacour in 1930.