Primates that spend their entire lives in trees tend not to survive after those trees are cut down. Sadly, that's what's happening in northeast India, where the forest habitats for one of the world's rarest apes are rapidly disappearing. The western hoolock gibbon (Hoolock hoolock) has lost an estimated 90 percent of its population over the past 25 to 30 years due to deforestation, hunting and government neglect, leaving its future very much in jeopardy.

Western hoolock gibbons are "very susceptible to habitat loss," says Florian Magne, founder and executive director of the HURO Programme, the only conservation organization dedicated to the species. "They do not adapt to degraded forests and they walk uncomfortably on the ground, where they are threatened by wild and domestic animals and diseases and are easy to locate and hunt because of their loud singing."

The loud hoots and hollers of the hoolock gibbon were once common throughout the seven sister states of northeast India (Meghalaya, Assam, Mizoram, Tripura, Arunachal, Manipur and Nagaland), as well as neighboring Bangladesh and Myanmar. Today, many of the areas that formerly echoed with the sounds of their calls are eerily silent. Recent articles from the Newmai News Network bemoaned the loss, although they inaccurately referred to the species as "black monkeys," the literal translation of the Meiteilon word yongmu, which is the local name for the species (only the males of the species are actually black). Hoolock gibbons are frequently mistaken for monkeys—a somewhat understandable error, since they only reach about 60 centimeters and weigh less than 10 kilograms—although they are actually lesser apes.

Hoolock gibbons are protected under Indian law, but Magne says that doesn't translate into much actual protection. He calls northeast India "completely unstable," a situation which drives both deforestation and wildlife loss. "Violent agitations, independence or autonomy demands, ethnic conflicts and militancy are common throughout the northeast," he says. "Such a situation doesn't allow properly planned development and constantly disturb projects and actions of the authorities. So in a virtual state of anarchy, the state governments mainly neglect wildlife protection, and NGOs commonly have no power or are corrupted."

Although Magne says he is optimistic about the western hoolock gibbon in the state of Meghalaya—where the HURO Programme operates a gibbon rescue center and works to educate local people about the species—the species is dire straits in the other six states and outside of India. "I personally went last year to Tripura, Nagaland, Mizoram and Manipur to assess the situation in those states, and the results are, unfortunately, not positive. Hunting occurs at high scale everywhere in Nagaland, Manipur and Mizoram without any control from the authorities, and gibbons are commonly killed and eaten, without distinction or control. Most of those places are very remote, out of the government control and have low education facilities and fragmented social systems."

With so many threats and such a dramatic population decline, Magne says each ape is vital to the survival of the species. The gibbons don't reach sexual maturity until they are about 10 years old, at which point they establish lifelong monogamous relationships. If a gibbon's mate is killed, it may never pair up again. The species, like many primates, also breeds quite slowly. Females only give birth once every two or three years, for a maximum of four or five offspring over their lifespans. On top of that, many gibbons may not even get the chance to breed. According to the IUCN's Primate Specialist Group, habitat fragmentation has isolated many of the animals into groups of smaller than 20. In some remote locations, only individual gibbons remain.

Magne says HURO has received strong support from the central Indian government, particularly from parliament member and animal activist Maneka Gandhi, but there is still much to be done in Meghalaya and elsewhere. He hopes the government and other international organizations will take up the challenge to build new rescue centers, create wildlife awareness programs to curb hunting, enforce existing laws and do more to protect the remaining forests from being cut down for lumber and agriculture.

The HURO Programme, which gets a majority of its funding from the Aspinall Foundation in the UK, currently has 10 gibbons in its care, the largest captive stock of the species in the world. You can see the rescue center and hear the gibbons' distinctive hoots and cries in this recent video:

By the way, the western hoolock gibbon is not alone in its plight. The similar-looking and ever-so-slightly less rare eastern hoolock gibbon (H. leuconedys) faces the same threats as the western species. Check out this video from the Wildlife Trust of India about the rescue of several eastern hoolock gibbons from a small clutch of trees after the rest of their forest habitat was cut down:

Previously in Extinction Countdown:

Photos by Sumeet Moghe via Flickr. Used under Creative Commons license