Variation in Bat Species Composition Along an Urbanization Gradient in the Mexican Tropics

Bat communities are affected by the constant growth of cities; however, urban and suburban environments can support distinct biological assemblages. In this study, we compared bat diversity (richness and abundance), structure, and dissimilarity of bat composition in four locations with different levels of urbanization in the Central Valleys of Oaxaca, southern Mexico. We monitored bats using mist nets during the dry and rainy seasons of 2020 and supplemented the inventory using acoustic techniques. A total of 20 species belonging to five families were recorded. The greatest number of species was recorded at the site with the lowest degree of urbanization; however, results indicate that while species richness and abundance varied among the sampled locations, the overlap in confidence intervals for most sites suggests a more complex pattern than a simple decline. Locations with higher impervious surface cover and lower canopy cover (NDVI) showed a biological trend toward lower species richness and abundance compared to semi-urban and rural sites. While the limited number of study sites precludes broad generalizations about urbanization mechanisms, the observed trends suggest that local habitat structure and vegetation density are key factors associated with bat presence in this tropical region. However, these trends should be interpreted as exploratory. These findings provide a baseline for future studies on the conservation of bat diversity in increasingly modified landscapes in southern Mexico.