The Lam Binh-Sinh Long area in Tuyen Quang is home to Vietnam’s largest population of François’ Langur, a globally Endangered monkey. It is one of several species of langur in Vietnam which are mostly black and sport a smart crest on their heads. They are usually distinguished from each other by unique patterns of facial and head coloring, with the François’ langurs having white stripes on their faces extending from the corners of their mouths to their ears.
Most of these langurs live on limestone mountains, where they are adept at climbing on the steep rocky cliff faces and use caves for shelter. Hunting has led to drastic declines in all langur populations in Vietnam, leaving them literally clinging to the edge of these dramatic limestone landscapes for survival.
PRCF has been working in the Lam Binh-Sinh Long area of Tuyen Quang since 2010 not long after the population of François’ Langurs was discovered there. Our work has been done in close collaboration with local communities, providing livelihood support to them and raising awareness of the status of François’ Langurs, while training local men to establish patrol teams to monitor and protect the langurs. PRCF has also been developing village institutions with the vision that in the long-term the communities themselves will be managing the forests to protect the langurs.
Surveys of the local langur population are an important means to measure the success of our work. In July 2020, our previous survey recorded at least 13 langur groups and up to 133 individuals in the area. During 2021, monthly monitoring was conducted by local teams, which recorded 16 groups with 156 individuals. Most of the team were local men from the patrol teams who were familiar with the terrain and already had a good understanding where the langurs might be found.
The 2020 survey was repeated in September and October 2023 using, as much as feasible, the same methods and a survey team of 17 people. A short survey in August had already identified the most current sleeping sites, usually caves, where the langurs are most likely to be active in the early morning or just before dusk, when they are easiest to observe. Altogether the survey team directly observed 16 groups of François’ Langurs, totaling 148 individuals. One more group was recorded from fresh fecal traces, bringing the total estimate to 17 groups and over 150 individuals, an increase on the 2020 census and consistent with the 2021 results.
In general, there is seen to be an increase in the number of young langurs and some females observed to be pregnant. All indicators are that this population of François’ Langurs continues to grow. Nevertheless, this is not the time to pack our bags and consider the job done. This langur population remains small and PRCF remains committed to supporting the local communities and monitoring the long-term survival of this charismatic monkey.
For more information:
Le, T.A.; Nguyen, A.T.; Le, T.S.; Le, T.A.; Le, M.D. Population Status and Conservation of the Largest Population of the Endangered François’ Langur (Trachypithecus francoisi) in Vietnam. Diversity 2024, 16, 301. https://doi.org/10.3390/d16050301
