VietNamNet Bridge – Biologists, rangers and researchers are all working together on a reintroduction programme for Hatinh langurs run by the Endangered Primates Rescue Centre (EPRC) in Ninh Binh Province. The langurs, who have been bred in captivity, are gently released into the wild, with rangers tracking them daily to see how they integrate into the wild for the first time in their lives. Hoai Nam reports.

Biological researcher Tran Ngoc Toan woke up when a signal rang out from his Global Positioning System (GPS).

Langur freedom: Hatinh langurs (Trachypithecus hatinhensis) are released into Ke Go Nature Reserve in central Ha Tĩinh Province during a reintroduction programme for Hatinh langurs by the Endangered Primates Rescue Centre (EPRC). Photo Tuan GreenViet

It was around 9am, a day after three Hatinh langurs (stripe-headed black langurs, found in the central province of Ha Tinh, scientifically called Trachypithecus hatinhensis) were released into the Ke Go Nature Reserve in the central province of Ha Tinh. The release was part of a reintroduction programme for Hatinh langurs run by the Endangered Primates Rescue Centre (EPRC) in Ninh Binh.

The detection device helped Toan get closer to where the three langurs – one male and two females – were seeking food in their new habitat.

He found them in high trees a few hundred metres from where they were released in the forest. They had started moving to find leaves and fruit to eat in the morning – their favourite time for filling up their stomachs before it gets hot at noon.

It’s the second time that first generation Hatinh langurs, which are captive-born individuals from the EPRC in Cuc Phuong National Park, have been returned to nature with the aim of increasing the population of the endangered species in the forest.

Chasing langurs: Biologists, rangers and researchers track Hatinh langurs in Ke Go Nature Reserve in Ha Tinh Province after the captive-born primates are released into nature. VNS Photos Cong Thanh

Last year, five captive-born Hatinh langurs were released in Ke Go Nature Reserve, but two of them died, one went missing and the remaining two returned to the EPRC.

“It’s a hard job for us when we have to track and supervise them twice a day in the first year. They were born and grew up in captivity in the EPRC, so it’s the first time they have actually returned to start a new life in the wild,” Toan said.

“They have to begin their wild instinctual lifestyle and get familiar with the new forest. They have to seek food, have sex and reproduce to build up a new flock of langurs,” he said.

Toan and his colleagues Hoang Quoc Huy and Bui Van Tuan from the Biodiversity Conservation Centre (GreenViet), an NGO in biodiversity communications in Viet Nam, work in shifts to observe the action of the langurs in their new habitat, making sure that they live well after being released.

“We have assigned a safe area of the forest where food is available for the langurs before they move further into the 45,000ha Ke Go Nature Reserve. Leaves and fruit are the main foods of the Hatinh langurs, so they should survive for the first year,” said Tuan.

“All the released langurs were equipped with tracking devices for the one-year supervision period, after which they will live by themselves in the wild as their ancestors did,” Tuan said.

Breaking free: Hatinh langurs start a new life in nature in Ke Go Nature reserve after a long time growing up in captivity.

After a lunch break, Toan returned to see how the langurs were doing. He was surprised to find that only the male and one female remained, while the other female had moved on.

Toan speculated that a war of love had occurred between the two females, and the smaller one had had to move away from the lone male langur.

“I guess that the bigger female won the war in the fight for the love of the male langur now they are ready to reproduce,” Toan said, adding that the strongest female often leads a flock.

Having completed a two-hour tracking and observation with the newly released langurs, Toan finally found that the male langur had moved to the highest tree to howl for hours for the missing female.

Tuan said they had started living in a new flock and the male needed more than one female for mating.

One month later, Huy reported that the three langurs had joined with a group to live peacefully in the forest.

Huy hoped the langurs would have more sex in season when spring food was plentiful and new offspring could flourish.

Tran Huu Vy, director of GreenViet, described the second release of captive born Hatinh langurs.

“The previous time we released them in the forest near a flock of monkeys, and the appearance of a new species in the forest sparked a war between them. The monkeys started attacking the newly released langurs, killing two of them,” Vy recalled.

Vy said a small langur without a tracking device was driven away by the monkeys and went missing in the deep forest.

He said local residents living around the forest recently found traces of the missing langur in the forest.

Vy said the wildlife reintroduction programme is a challenging endeavour for biologists in Viet Nam as it was difficult to keep captive born primates alive in the wild.

“They get familiar to the support from caretakers with food, medicine and protection, so they often find it hard to return to nature where their ancestors lived,” Vy said.

“They have to relearn their basic wild instincts of seeking food, regrouping and getting herbs to prevent diseases. Serious pollution, illegal logging, hunting and the expansion of farms into the forest have threatened many wild species and primates with extinction,” Vy warned.

He said the release of captive born species and primates would trigger the revival of endangered species and increase the biodiversity of the forest.

Reintroduction

The Hatinh langurs, which are listed as endangered species by the International Union of Conservation of Nature (on the IUCN Red List of Threatened Species), exist only in a restricted area of central Viet Nam and eastern Laos.

Observing: A ranger gets closer to a newly released Hatinh langur in the forest of Ke Go Nature reserve in Ha Tinh Province.

The largest population of 200 individuals can be found in Quang Binh, and a small population lives in Quang Tri.

Tilo Nadler, director of the Endangered Primate Rescue Centre in Cuc Phuong National Park, said the initial discovery and scientific description of Hatinh langurs was not actually done in Ha Tinh, but in Quang Binh.

“We started the first reintroduction programme for Hatinh langurs as a pilot project in Phong Nha-Ke Bang National Park six years ago. We have released eight captive-born individuals from the EPRC into a very large, electric fenced semi-wild area,” Nadler said.

“The animals have produced a number of offspring and the population has now increased to 24 or 25 individuals.”

He said an important conservation effort for rare and endangered species should be the establishment of at least a second viable population.

He explained that a single population can be at risk from a number of impacts – natural disasters, diseases and high local hunting pressures, so he chose Ke Go Nature Reserve as a place for the establishment of a second population, as the forest in the reserve is in good condition.

“The first release of five langurs in the reserve last year ended unfortunately with a completely unexpected disaster. But the release of animals, especially captive born ones, is always risky and often ends in failure.

“With this new attempt we hope to have a good start, and the captive population at the EPRC can provide a sufficient source of individuals to continue the project if it shows success this time,” Nadler said.

He said about 80 Hatinh langurs have been born at the EPRC, not all grown up as yet, but this stock could provide individuals for the establishment of a viable wild population.

Nguyen Quang Chau, deputy director of Ke Go Nature Reserve, said the forest is an appropriate habitat for the mass development of Hatinh langurs.

“The reserve is surrounded by 28,000ha of Ke Go reservoir and the approach of local residents is limited. We also have co-operation with local residents living in eight communes within the buffer zone to protection of the flora and fauna in the reserve,” Chau said.

“The reserve with a capacity of 345 million cubic metres of water, and is abundant with aquatic species, but it also provides water for over 18,000ha of rice farms in the three districts of Thach Ha, Cam Xuyen and Huong Khe,” Chau said.

Chau said the reserve management allows local people to fish in the reservoir to supplement their diet, and they act as informers of illegal logging and hunting in the forest.

He said that fishing in the reservoir was a breadwinner for the 50,000 population in the reserve’s buffer zone.

VNS