Gibbon Discovery Gives Hope for Survival of Species

After three years of hard work in some of the most remote and dense forests of Vietnam, CI primatologist Ben Rawson and his team have confirmed the largest population of the critically endangered northern white-cheeked crested gibbon (Nomascus leucogenys) in the country. Here, Rawson recounts his experiences in making this important discovery.

Northern white-cheeked crested gibbon in Vietnam. Adult female with baby and adult male. Photo: © Terry Whittaker

I have worked with gibbons for the past 10 years, and the more I learn about them, the more I admire them and the more concerned I become about their future. All 25 of the world’s gibbon species and sub-species are threatened with extinction, with wild populations suffering from hunting and habitat loss and degradation. Given this depressing outlook, our recent discovery in Vietnam of the only known viable northern white-cheeked crested gibbon population left in the world is a beacon of hope for this amazing primate.

Despite the species’ historical range across southern China, northern Laos and Vietnam, the species is now believed to be functionally extinct in China, and populations in Laos — while potentially significant — are unknown. However, recent studies on the vocalizations and genetics of the Nomascus genus showed that its habitat range could extend further south than originally thought. Within this new range stands Vietnam’s Pu Mat National Park, which contains high-altitude pockets of pristine forest, isolated from human disturbance due to its remote location. It was feasible that a gibbon population could exist there, unknown to the outside world, and so it was there in these harsh climes that we focused our efforts.

Field surveys in these conditions are tough. It can take days to access survey locations, slogging along rivers through dense forest and up impossibly steep slopes. Reaching these distant locations, we get up hours before dawn to climb to the top of mountains and ridges in pitch black to await the haunting calls of gibbon mated pairs, which can be heard from several kilometers away.

Field surveys in Pu Mat National Park, led by my friend and colleague, Luu Tuong Bach, have determined that a population of 130 groups, or about 455 individuals, of the northern white-cheeked crested gibbon persist here. This represents probably two-thirds of Vietnam’s entire population of the critically endangered species, which has been almost completely decimated in all other locations.

Listen to the whooping call of the northern white-cheeked crested gibbon.

Unfortunately, ongoing road construction in this area is threatening the gibbons’ remote existence which has been essential to their survival. These new roads, designed to increase border patrols between Vietnam and Laos, will cut directly through the gibbon’s habitat — a development which could have catastrophic effects on this gibbon population by fragmenting their habitat and increasing human access to these regions, which may encourage illegal and harmful activities such as hunting and logging.

Without protection, this threat will inevitably lead to negative impacts on this last refuge for northern white-cheeked crested gibbons in Vietnam. Protection of this population is the highest national and global priority for the species’ survival.

Ben Rawson is a primatologist and the Veun Sai forest manager for CI’s Greater Mekong Program.