Rural occupancy in a montane burrowing snake: the importance of thermal and microhabitat resources during the rainy season

Abstract

Thermal and microhabitat resources are two fundamental requirements that affect the life history of any ectotherm. Furthering our understanding of how reptilian species meet these ecological requirements is crucial for assessing the impact of environmental and anthropogenic changes on populations. Here, we explored some fundamental aspects of the thermal and microhabitat ecology of Conopsis biserialis, a small, burrowing, and endemic earthsnake of central Mexico. The study was conducted during the rainy season in a montane site disturbed by rural activities. The mean field body temperature (Tb) of C. biserialis was 26 ± 0.6 ºC. Field Tb did not differ significantly between sex and development stages. However, we found that Tb was positively correlated with substrate, air, and under-rock temperatures (Ts, Ta, and Tr) in the rural microhabitat. Regression analysis showed that substrate and under-rock temperatures (Ts and Tr) were the parameters that best explained Tb variability in the individuals. The temperature and relative humidity under shelter did not differ significantly among shelter types and/or rock sizes. In addition to these thermal traits, earthsnakes selected and utilized six common biotic and physical elements of the rural microhabitat. Most individuals used high proportions of large and medium rocks for sheltering, and these rocks were selected around crop fences and cleared grasslands where the soil can be either covered with low vegetation or bare. Our results suggest that, during the rainy season, individuals of C. biserialis use and select some biotic and structural resources of the rural microhabitats, and were capable of actively regulating their temperature by using shelters with high values of microclimatic homogeneity.