Thermal ecology of the Mexican Garter Snake (Thamnophis eques): temporal and spatial variations

Heterogeneous environments provide different daily and seasonal thermal conditions for snakes, resulting in temporal and spatial variations in body temperature (Tb). This study analyzes the Tb of Thamnophis eques in the forest and grassland of a Mexican locality through daily and seasonal profiling. The patterns were obtained from seminatural enclosures in the field with a point sampling strategy to analyze temporal and spatial variations in Tb. The variation of Tb throughout the day was correlated with air and substrate temperatures, both in the grassland and in the forest. The average Tb in the grassland was 0.88 °C greater than in the forest. Our results indicate that T. eques showed differences in Tb between grassland and forest, principally in late spring and early summer during the early rise and late plateau phases, coinciding with the presence of foliage on the willow trees present in the study area, while in late summer and early autumn, the Tb was similar when willow trees canopy cover was absent (May-September). Our results support the hypothesis that the Tb of snakes differ between forests when the willows have leaves and is similar when canopy cover is equivalent, in this case, when tree canopy cover was absent. Our results also shown that T. eques presented daily and seasonal warming patterns similar to other Arizona populations and like those of other northern Gartersnakes. However, this result may not be valid for the entire wide distribution and consequent diversity of habitats of T. eques. The information of Tb in T. eques through daily and seasonal profiles in different habitats could aid in understanding the effects of environmental conditions on the ecological strategies deployed by snakes on habitat selection.