Effect of habitat structure on abundance and body conditions of two sympatric geckos, Cyrtodactylus saiyok and Cyrtodactylus tigroides, in the karst forest of western Thailand

Deforestation is a major threat to biodiversity worldwide, especially in Southeast Asia. In western Thailand, reptiles are an important part of tropical rainforest ecosystems and karst forests. However, basic ecological studies of many species are largely lacking. Therefore, we studied two sympatric gecko species, Cyrtodactylus saiyok and C. tigroides, that inhabit karst forests and are restricted to western Thailand. We investigated the habitat variables that affect their abundance and body condition in Kanchanaburi Province in western Thailand. We found that the abundance of C. saiyok increased with increasing plant density and decreasing canopy cover. For both study species, body condition was positively correlated with canopy cover. The two species differed in their microhabitat use, and C. tigroides prefers more karst outcrops and stays higher above the ground. Our findings highlight the importance of an intact forest structure for the survival of geckos and thus reiterates that it is crucial to conserve karst forests in Southeast Asia.