Abstract:

Aim: Identifying the microhabitat selection characteristics of endangered species is essential for developing effective conservation strategies. The Chinese crocodile lizard (Shinisaurus crocodilurus) is a critically endangered species worldwide, with fewer than 1,500 individuals remaining in the wild. This study aimed to systematically analyze the influence of various microhabitat variables on the microhabitat selection of crocodile lizards. 

Methods: We carried out microhabitat quadrat investigations in the stream environments where crocodile lizards are distributed within the Luokeng Chinese Crocodile Lizard National Nature Reserve in Guangdong Province. We used random forest model and generalized linear mixed-effects model to assess the key microhabitat variables that determined the occurrence of crocodile lizards. 

Results: Random forest analysis revealed that perch density, stream depth, stream sand coverage percentage, canopy closure, stream velocity, and stream width were the critical microhabitat variables affecting the occurrence of crocodile lizards, each with specific ecological thresholds. The final GLMM indicated that perch density, stream depth, canopy closure, and stream width all exhibited significant positive associations with the occurrence probability of the crocodile lizard. Among these variables, perch density was identified as the primary influencing factor, followed by stream depth. Despite its modest independent contribution, canopy closure served as an indispensable underlying factor, whereas stream width was determined to be a marginal factor, exerting a limited effect. 

Conclusion: Our study highlights that improving perch density should be prioritized in the conservation of crocodile lizards. Simultaneously, measures such as improving the hydrological environment and optimizing canopy closure should be implemented to provide more suitable microhabitats for the population. These findings contribute to a better understanding of the microhabitat requirements of crocodile lizards and provide scientific basis for targeted conservation actions.

Key words: microhabitat selection, random forest model, generalized linear mixed models, perch density, crocodile lizard