Abstract
Abstract
Species–environmental relationships, including drivers of body temperature (T
B), are important for understanding thermal ecology and physiological needs of species during climate change. This is especially important among ectotherms, including amphibians and reptiles (i.e., herpetofauna), in aridland riparian systems. Infrared thermography (IRT) can reliably and noninvasively estimate T
B of ectothermic herpetofauna while simultaneously assessing thermal heterogeneity across a mosaic of microhabitats. We used IRT at a semi-arid riparian zone in Tucson, Arizona to assess herpetofauna–environmental relationships during early-season activity periods in 2020 and 2022. From mixed-effect modeling of desert riparian herpetofauna (n = 81), we found complex environmental relationships influencing T
B. Microhabitat perch surface temperature (T
S) best explained T
B; many ambient conditions were inadequate at capturing T
B. Herpetofauna were as warm by mid-morning than in the early afternoon, with T
B approaching equilibrium with T
S as mornings progressed. Less T
B–T
S variation was detected for anurans (e.g., canyon treefrogs, Hyla arenicolor) than with lizards, supporting that desert amphibians are sensitive to the thermal landscape. There was also complex environmental variation among thermally heterogeneous microhabitats used and available to herpetofauna. As perch T
S increased, shade became more important, though shade sources may be less relevant. The methods and data obtained in this study can serve to establish baselines during seasonally and ecologically important periods and be used to monitor thermal ecology changes across time for herpetofauna or taxa with similar life history in aridland riparian systems. Although ectotherm thermoregulatory functions are undeniably complex, we recommend IRT as a rapid, noninvasive, and complementary tool to monitor cryptic thermal ecology in heterogeneous systems. Understanding species–environmental relationships and monitoring responses of wildlife across time can help guide more effective biodiversity conservation management strategies in a warming and drying world.