Restoring a tree canopy has reunited families of Hoolock gibbons after a 132-year separation.
Sixty-two-year-old Jiban Borha was born in a village near the Hollongapar Gibbon Wildlife Sanctuary in India’s Assam State. When he was a child, the sanctuary was his playground, and for the past twenty years, he has worked there as a guide.
Spread across 2,098 hectares, the sanctuary is the protected home of the Western Hoolock gibbon, India’s only ape. The sanctuary houses six other species of non-human primate, including the capped langur, stump-tailed macaque, pigtail macaque, Assamese macaque, rhesus macaque, and slow loris, as well as forty-one species of mammals. But Borha has always had a private aspiration: the reunion of families of gibbons, separated for well over a century by a 1.6 kilometer-long railway line constructed in the late 1800s. He never imagined he’d see that reunion in his lifetime.
Gibbons are currently listed as “endangered” under the International Union for Conservation of Nature’s Red List of threatened species. There are an estimated 2,600 gibbons in the wild, primarily in Myanmar, Bangladesh, and the northeastern states of India. They live in natural tree canopies, but massive deforestation has created habitat loss, which threatens their survival. In the wild, they live about thirty years — up to fifty years in captivity.
Gibbons in Assam State connected with each other via a tree canopy until a swath of trees was removed to make way for the railway in 1887, during colonial rule. The removal of these trees has meant the separation of families of gibbons for roughly four generations.
In 2006, environmental activists, together with a non-profit environmental group called Aaranyak (“of the forest”), began planting fast-growing saplings — thousands of them — on either side of the railway tracks. When the trees matured, their planters expected that they’d form natural canopy bridges, arching over the railroad tracks and connecting the gibbons.
“Around 3,000 saplings were planted on either side of the railway track with the help of locals and the forest department,” said Dilip Chetry, head of the primate research and conservation division at Aaranyak. Among the saplings are seventy-one species favored by gibbons as food sources and sleeping trees.
On October 20, 2019, at 8:15 a.m. — exactly 132 years after his forebears’ families were separated — a male gibbon used the canopy to reach those on the other side of the tracks. Jibon Borha was among a handful of staff who witnessed what he called “an emotional moment,” saying, “it is almost impossible to explain the feelings in words when we witnessed the first crossover. Our hearts were full of emotions and tears welled in our eyes as we saw them uniting with each other.”
Since then, gibbons have been using the canopy regularly.
Borha, however, would still like to see the railway track rerouted outside of the forest. “The loco drivers have to maintain speed restrictions while crossing through the sanctuary,” he said, “but some of them ignore [speed limits], and that results in the killing of wild animals.” The area serves as an elephant corridor, he noted, and elephants have been killed by trains. “We have been requesting the authorities to divert the route of the track to outside the sanctuary so that wildlife can survive in peace,” Borha said. “But nothing has been done yet. Passengers also throw plastic and other waste that pollutes the forest.”
Nandha Kumar, the Divisional Forest Officer (DFO) in the Indian Forestry Agency, under whose jurisdiction the sanctuary falls, estimated that around fifteen to twenty families of gibbons live inside the sanctuary. “Each family has around a maximum of five members,” he said, “and the last census, done in 2019, [estimated] sixty-five gibbons in total. We believe the population still to be the same, and the natural canopy has certainly helped the gibbons to unite after a gap of over a century.”
Jabor Borha remains elated at the gibbon reunion. “It is unbelievable to see gibbons swinging from one canopy to another and going to other parts of the forest, which was not possible before,” he said, noting that he had spent his lifetime praying for this moment. “I think prayers have been answered.”