Of these, 56 individuals are distributed across the communes of Dong Hoa, Thach Hoa, and Thuan Hoa, inhabiting limestone karst formations adjacent to human settlements and agricultural lands. The population is structured into 22 social groups, with the following distribution:
- Thach Hoa Commune: 12 groups comprising 91 individuals
- Dong Hoa Commune: 9 groups comprising 57 individuals
- Thuan Hoa Commune: 1 group comprising 8 individuals
Furthermore, surveys conducted by CIRD – CEGORN have identified the presence of another primate species in the region: two troops of stump-tailed macaques (Macaca arctoides), totaling 30 individuals, located in Dong Hoa and Thuan Hoa communes.
The white-naped black langur is currently classified as Critically Endangered in the Vietnam Red Data Book. Its known distribution is highly restricted, with populations confined to Quang Binh Province, a few small groups in Quang Tri Province, and a limited range extending into Khammouane Province, Laos, adjacent to the Phong Nha – Ke Bang World Heritage Site.
The full report is available for Langur in Quang Binh – Final.pdf
