Plastron‐mounted loggers predict terrestrial turtle body temperature better than carapace‐mounted loggers

Abstract

ABSTRACTStudies of thermal ecology are imperative for understanding habitat use and selection by animals and can inform management decisions for conservation of species and habitat. Chelonian thermal ecology studies have used carapace measurements as proxies for body temperatures despite recorded differences exceeding 5° C. Although implanting temperature loggers is the optimal method for measuring body temperature, performing implantation surgery is not always a feasible option. Additionally, differences in thermal properties of a carapace‐mounted temperature logger and turtle shell may alter how we interpret these data. We sought to validate a less invasive approach to measure body temperature in terrestrial chelonians using eastern box turtles (Terrapene carolina carolina; captured in southwestern Ohio, USA, during 2014 and 2015) to assess the accuracy and precision of external placements. Our goal was to determine the optimal external temperature logger placement for predicting body temperature and compare specific heat capacity of loggers and turtle shell to assess their use as proxies for body and microhabitat temperature. We found that placing the temperature logger on the plastron of the turtle was a better predictor of body temperature than using a carapace logger, and the combination of both loggers had the best predictive value. We argue that for thermal ecology studies informing management and conservation decisions in terrestrial chelonians, the carapace temperature logger is a better indicator of ambient temperature and the plastron temperature logger is a more appropriate proxy for body temperature. © 2019 The Wildlife Society.