Meeting Abstract
Ever since Cowles and Bogert demonstrated that reptiles could thermoregulate using behavior, investigators have developed various methods to show that these temperatures were not simply a passive response to the environment. Initially, sophisticated mathematical models calculated the energy balance of an animal at a specific point in time. Operative temperatures (Tes) from these calculations describe the instantaneous temperature for an animal given absorptive and convective properties, but with no heat capacitance. State of the art techniques were then developed, using hollow metallic replicas of animals, to approximate the Tes of individuals measured in real environments. When sampled over an environment, Tes can be used to benchmark thermoregulatory performance. Further, Tes can be used to calculate the body temperatures (Tbs) of individuals in a transient environment if additional information regarding thermal time constants are known. For various reasons, many biologists have substituted hollow metallic replicas with other types of inanimate objects, sometimes adding thermal mass to approximate a Tb rather than an Te. In doing so, investigators have introduced errors into their work as their models have a substantial time lag, and are no longer taking direct measurements of Te that could be used to examine thermal forcing in a changing environment or microhabitat (e.g. when thermoregulating). Here, we review the recent literature to 1) highlight the inappropriate measurement of Tes and its consequences, 2) suggest methodologies that might be able to correct some of these poor measurements, and 3) connect measurements of Tes back to the original underlying theory. Our hope is to clear up some fundamental misunderstandings of what Tes provide and to suggest future directions whereby correct measurements can advance our understandings of thermal biology.
