Villagers in Barekuri, Assam, have lived closely with endangered hoolock gibbons for generations. A new Guardian documentary shows their bond – and the fight to protect them

On a misty winter morning, farmer Mohit Chutia sits on the ground outside his home rocking his grandson in his lap. He sings about the hoolock gibbons, the only ape species in India. High in the tree canopy above, the gibbons leap gracefully from branch to branch. Below, Chutia and his family watch.

It is a picture of the coexistence that has endured for generations between the endangered gibbons and villagers in Barekuri in Assam, in the remote east of the country.