The bridge over the Assam rail track. (Source: Express Photo by Samudra Gupta Kashyap) The bridge over the Assam rail track. (Source: Express Photo by Samudra Gupta Kashyap)

A dozen forest guards in upper Assam’s Holongapar reserve forest have a new responsibility. Led by beat officer Sushil Kalita, they must keep constant watch on a ‘bridge’ across a railway track passing through the forest. Last week, says Kalita, they had their first good news. “At least one gibbon was seen climbing one of the two trees to which the bridge is connected.”

One day soon, it is hoped, hoolock gibbons living in the northern part of the forest, designated the Gibbon Wildlife Sanctuary in 1997, will use the bridge to visit fellow gibbons in the southern part, and vice versa.

The track, laid by the British to connect Dibrugarh with Chittagong through Lumding, cut the sanctuary into two parts at the turn of the last century. Since then, several gibbon families in the southern half have remained cut off from the majority on the northern side.

The Railways finished constructing the ‘canopy bridge’ only recently, with funds from the state forest department. “We have constructed it with utmost care as suggested by the forest department,” says a spokesman of the Northeast Frontier Railway in Guwahati.

However, Dilip Chetry, executive director of the Gibbon Conservation Centre at Holongapar, cautions that the gibbons may not start using the bridge soon. “Being genetically very close to human beings, they will examine all the pros and cons before actually venturing to cross it. Right now they have not even touched it.”

Though no recent figure of gibbon population in the sanctuary is available, the last census, of 2009, showed it had 25 families, comprising about 125 gibbons. Chetry says while they are known to live up to 35-37 years in the wild, the southern gibbons isolated by the railway track “must have developed serious genetic problems”.

“It appears that their numbers are dwindling. Only a thorough scientific study will tell us the exact genetic deterioration they have suffered,” he says.

Joyram Baruah, an assistant conservator of forests, says, “The idea of a canopy bridge was first mooted about 10 years ago, but came through only now, after the forest department convinced the Railways and also provided about Rs 8.34 lakh for the purpose.”

Hoolock gibbons (Bunopithecus hoolock) are the only ape species found in India, with the entire stock confined to the Northeast.

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