Northeastern India is home to two ape species: eastern and western hoolock gibbons.Populations of hoolock gibbons in India are both protected and harmed by practices and beliefs specific to the human communities with whom they share their habitats.In several gibbon habitats, local indigenous people are leading conservation efforts that are deeply informed by local circumstances.The fortunes of different gibbon populations within India show that there is no one-size-fits-all conservation strategy for apes. A typical morning in the village of Phlangwanbroi starts with a melodious yet primitive-sounding song: drifting over from the nearby community forest, a series of whoops, hoots and tones rise in a crescendo. It’s hooleng jingrwai — the hoolock gibbon’s song. Perched atop a rain-soaked plateau in the Indian state of Meghalaya, Phlangwanbroi is a Khasi tribal village. The Khasis are a hill-dwelling indigenous minority numbering about 1.2 million within India. Located in the country’s remote mountainous northeast, most Khasis in rural Meghalaya continue to practice their hardscrabble traditional lifestyle, relying for the most part on subsistence agriculture and forest resources. Phlangwanbroi, four neighboring villages and an adjoining community forest make up the Khasi native state of Hima Malai Sohmat, one of 25 such traditionally ruled Khasi enclaves in Meghalaya that are formally recognized by the Indian Constitution. The 40-square-kilometer (15.4-square-mile) community forest of Hima Malai Sohmat has been home to western hoolock gibbons (Hoolock hoolock) since time immemorial, villagers say. But an ever-increasing human pressure is gnawing away at the forest, endangering the hooleng, as the species is called in the local Khasi language. The western hoolock gibbon is threatened globally, too. Conservationists say the future of the IUCN-listed endangered species is very much in jeopardy. An estimated 90 percent of its population has been lost over the past 30 years due to deforestation, hunting, and government neglect. Around 3,000 western hoolock gibbons are believed to remain, some 2,600 of them in northeastern India and the rest scattered in Bangladesh, Myanmar and perhaps southern Tibet. “Today hoolock gibbons are facing existential threat primarily due to many types of habitat loss — habitat destruction, habitat fragmentation, and habitat degradation,” says Narayan Sharma, a primatologist at Cotton University in Guwahati, in neighboring Assam state. A western hoolock gibbon. The arboreal species is so reluctant to spend time on the ground that even the loss of a single connecting tree can render forest fragments inaccessible to them. Image by Saurabhsawantphoto via Wikimedia Commons (CC BY-SA 4.0) As an exclusively arboreal species that requires contiguous, closed-canopy forests for survival, the hoolock gibbon is particularly vulnerable to the massive ongoing deforestation across northeastern India. “When a contiguous habitat is reduced to scattered smaller fragments, they become ‘habitat islands’ in an inhospitable sea of degraded habitat,” says Sharma. These conditions can lead to inbreeding, he adds. “The resultant offspring are often weak, sometimes sterile or may have little reproductive fitness.” Hoolock gibbons rarely move between forest fragments; they may refuse to cross gaps even as small as 200 meters (660 feet). On top of that they’re extremely picky about their food, and a restricted home range means limited food options. Wildlife biologist Kashmira Kakati, whose doctoral research at the University of Cambridge was on Assam’s hoolock gibbons, recalls a gibbon family she observed during her fieldwork. “An entire portion of their home range became inaccessible via the canopy because a single connecting tree was felled,” she says. “I witnessed severely emaciated juvenile gibbons — a phenomenon that occurs when they’ve to feed on leaves for prolonged periods in the absence of fruits.” Gibbons are vulnerable to such threats even within protected areas. In the Hollongapar Gibbon Wildlife Sanctuary in Assam’s Jorhat district, a railroad that predates the sanctuary’s establishment splits the park in two, leaving a small, isolated population in the park’s east. “A few years ago, a canopy bridge was erected over the railroad hoping that it would help the two groups connect to each other,” says Deben Bora, a forest guard who doubles as a guide for visitors to Hollongapar. “But the gibbons never came anywhere near the bridge.” Similarly, Mehao Wildlife Sanctuary, a key protected hoolock gibbon habitat, is losing its forest cover due to illegal logging, land encroachment and expansion of agriculture, notably oil palm cultivation.