The Influence of Habitat on Body Temperature Regulation in the Timber Rattlesnake (Crotalus horridus)

Abstract

Ectothermic vertebrates are dependent on the availability of environmental temperatures and their ability to behaviorally thermoregulate to maintain a suitable range of body temperatures. In heterogeneous landscapes, such organisms often will encounter a variety of habitat types which impose different environmental conditions for thermoregulation. This study examines the thermal qualities of different habitats within a heterogeneous landscape in Middle Tennessee and infers how this variation may influence body temperature regulation in a population of Crotalus horridus. Comparison of four habitats (field, cedar glade, hardwood forest, redcedar forest) indicated considerable variation in environmental temperatures. Nevertheless, C. horridus maintained similar body temperatures in all habitats despite the limited availability of suitable temperatures in the field and cedar glade. An index that assesses the effectiveness of thermoregulation was applied to each habitat and indicated high thermal quality in the hardwood forest and redcedar forest compared to the field and cedar glade. These findings imply that C. horridus would need to actively thermoregulate more in the field and cedar glade but could rely on thermoconforming behavior in the hardwood forest and redcedar forest. This study illustrates that different habitats may significantly influence the amount of effort a snake such as C. horridus may have to expend in order to thermoregulate and maintain appropriate body temperatures.