Handle with care: the thermal consequences of short-term handling in mole salamanders

Accurately measuring body temperature is critical for understanding how ectotherms interact with their thermal environment. In amphibians, traditional methods like cloacal thermometry require restraint, potentially altering body temperature through stress and heat transfer from human hands. Here, we used infrared thermography to examine how short-term gentle handling (2 min) impacted skin temperatures (T_skin) in two species of mole salamanders (Ambystoma laterale and A. maculatum) by combining field and lab experiments. In the field, we randomly assigned salamanders to a handled or control group, whereas in the lab salamanders were assigned to a heating plate set to hand temperature or a control group. We also scored salamander activity (active vs. inactive) in both settings. In the field, handling increased T_skin in both species, with the head warming up more than the dorsum. Moreover, A. laterale experienced an overall greater magnitude of thermal change (ΔT_skin) than A. maculatum due to body size differences. In the lab, contact with the heating plate increased T_skin, with head T_skin being consistently warmer than dorsal T_skin. We also found that ΔT_skin was greater for the handled than the heating plate group (ΔT_skin = 4.86 ± 1.21 °C vs. 1.72 ± 0.70 °C, respectively), suggesting that handling may amplify heat gain. Warmer salamanders were more prone to be active regardless of whether they were handled or in contact with a heating plate. Our results demonstrate that short-term handling can cause rapid warming that exceeds rates used in heat stress studies, with implications for data reliability and amphibian welfare in thermal biology assays.