Good news for gibbons

Gibbons are one of the most critically endangered primates in Bangladesh. Though once a prominent species, their numbers have dwindled due to continued loss of habitat and hunting.

To preserve their habitat in Bangladesh, five canopy bridges have been constructed in Moulvibazar's Lawachhara national forest, to facilitate the free movement of Hoolock gibbons who inhabit the area.

This was done to create a connection between two sides of the forest cut across by a railway and a road. The bridges were built by tying ropes between branches of two tall trees on either side of the divide, which the gibbons can use as crossings, said Rezaul Karim Chowdhury, divisional forest officer of the Department of Wildlife Management and Nature Conservation.

Shamsul Haque, joint convener of Lawachhara Bon O Jiboboichitro Rokkha Andolan (Lawachhara Forest and Biodiversity Conservation Movement) said, the Dhaka-Sylhet railway line and the Srimangal-Bhanugach road cut through the Lawachhara National Park, dividing it into two sides.

The road and railways are very wide, he said, which means most inhabitants of the forest cannot jump across from one tree to another.

The canopies were set up between September 2 and 5. Though three tree bridges were built in Satchhari National Park for civets recently, this is the first time these bridges have been set up in Lawachhara, forest officials said.

A six-member research team under the supervision of Dr Habibun Nahar, associate professor of Jagannath University, has undertaken the initiative, funded by Bangladesh Forest Department.

According to a 2019 survey, there are 40 to 41 Hoolocks from 13 families in Lawachhara National Park. In 2008, there were 35.

According to a 2016 survey, there were 400 Hoolocks across 22 areas in the country, including in Lawachhara, Adampur, Satchhari, Rema-Kalenga, all in Sylhet region.

Habibun Nahar, associate professor of Jagannath University's Department of Zoology, has observed Hoolock gibbons' movement in the area since 2019.

Talking to this correspondent, Nahar, also leader of the research team, said, "During noon, there are no trains travelling on the railway. If the gibbons could, they would crossover [to the other side] during this time. Unfortunately, they can't do that due to the way the forests are disconnected."

"Lawachhara has a suitable environment for Hoolock gibbons. Their population is growing. But if they are confined within a limited space, there will be competition. The canopy initiative was thus undertaken to allow them to breed more freely," she said.

"Initially, the artificial canopy bridges have been set up at five places in Lawachhara, funded by the forest department," she said. "We will be monitoring these. If they yield good results, we will build similar structures in other places of the country."

She said an adult gibbon is about 60 to 90 centimetres long and weighs six to nine kilogrammes. Although male and female gibbons are almost identical in size, there are significant differences in skin colour.

A male gibbon is coated with black fur and has white eyebrows, while a female gibbon has grey-brown hair all over her body. The hair around their neck is blacker and eyes and mouth are covered with white fur, like a mask.