Wild Chinese giant salamander persist in Zhangjiajie, Hunan, China: Evidence from 10 years of monitoring

As a critically endangered species, the Chinese giant salamander (CGS) is of both theoretical and practical importance in conservation biology. This study applied a multi-scale, integrated approach to characterize its reproductive ecology, combining long-term field monitoring and molecular methods. From 2005 to 2014, fixed-site surveys were conducted at nine representative breeding caves in Zhangjiajie, China. In 2023, environmental DNA (eDNA) technology was introduced to reassess the current distribution of wild populations. Results showed marked differences in larval emergence among caves, with annual averages ranging from 15 to 822 individuals. Emergence patterns were primarily influenced by shading, river width, flow rate, and dissolved oxygen. The timing of emergence displayed spatiotemporal gradients from December to February, as well as a distinct diel rhythm, with significantly higher emergence between 19:00–23:00. Behavioral observations recorded the color-changing process of CGS larval upon exiting the cave. The body color darkened rapidly under stronger illumination, and typically reached completion within 4–12 hours. Notably, eDNA analyses confirmed the persistence of species-specific DNA fragments in several historical sites where no larvae had been observed for over five years. These findings suggest the continued survival potential of wild individuals in areas previously considered unoccupied. By integrating conventional ecological monitoring with eDNA analysis, this study addresses critical gaps in knowledge of the reproductive ecology and spatial persistence of the CGS. The combined framework establishes a robust foundation for targeted conservation strategies and future management of this iconic amphibian. • ・Long-term monitoring revealed cave-specific differences in larval emergence. • ・Larval emergence showed seasonal (Dec.–Feb.) and daily (19:00–23:00) rhythms. • ・First documentation of larval color change unveils that light accelerates darkening (4–12 h). • ・Wild CGS DNA was detected in 2023 in caves with no larvae sightings for over five years. • ・Integrated field and eDNA approaches inform targeted conservation strategies.