Publication: New Insights into the Distribution of White-Cheeked Gibbons in Central Lao PDR

We are pleased to share our publication in the International Journal of Primatology, which sheds light on the distribution of the northern white-cheeked gibbon (Nomascus leucogenys) and southern white-cheeked gibbon (Nomascus siki) in central Lao PDR. Our study (Coudrat et al., 2025) utilized acoustic analysis to clarify species boundaries, with implications for conservation and management strategies.

Methods and Key Findings

• Acoustic Analysis for Species Identification – We analyzed 90 gibbon songs from the wild in Lao PDR and Vietnam, along with 32 recordings from identified species obtained from zoological facilities. Our analysis of vocalizations from zoological facilities identified significant differences in male and female vocalizations, which we applied as training data in a machine learning classification analysis (Random Forest analysis), achieving an accuracy of 97% for males and 89% for females. This method proves to be a valuable tool for species identification in conservation programs.

• Geographic Overlap of Species – The study found both species present on both sides of the Nam Theun-Nam Kading River, challenging the previous assumption that this river serves as a strict geographical barrier between them. This new evidence suggests a more complex distribution pattern and possible interactions between the two species.

• Implications for Conservation – The presence of both species in overlapping ranges raises concerns about hybridization, which could impact conservation efforts. The findings emphasize the need for careful species identification before engaging in reintroduction or translocation programs to prevent genetic mixing and ensure effective management.

• Policy and Future Research – This study highlights the importance of conducting further genetic and ecological assessments to refine conservation strategies. Governmental and conservation organizations must consider these findings in ongoing biodiversity monitoring and protection initiatives in Nakai-Nam Theun National Park and surrounding areas.

A Call for Action

The research underscores the necessity of informed conservation planning to protect the distinct populations of Nomascus leucogenys andNomascus siki. With the threat of habitat loss and hunting, efforts must be reinforced to safeguard these endangered primates and their ecosystems.

For further details, the full publication is available in the International Journal of Primatology. or below: