KROCHMAL, A.R.*; BAKKEN, G.S.: Evidence for the Use of Facial Pits for Behavioral Thermoregulation In the Western Diamondback Rattlesnakes (Crotalus atrox)

Pit vipers (Crotalinae) possess unique organs, called facial pits, which can detect subtle fluctuations in emitted thermal radiation. Facial pits are used for prey location and strike direction, demonstrating that pit vipers can incorporate thermal information into their behavioral patterns. Though never thoroughly investigated, such thermal information could play a significant role in the thermoregulatory behavior of pit vipers. Behavioral thermoregulation can impact social and foraging behaviors, increase predation risk, and impart physiological costs. Locating thermally favorable microsites efficiently would minimize these constraints, and the ability to do so should be favored by natural selection. Emitted thermal radiation is a direct indicator of an object’s surface temperature, and the ability to use it as a behavioral cue would allow pit vipers to efficiently detect thermally favorable microsites. Therefore, we hypothesized that pit vipers might use their sensitivity to emitted thermal radiation to locate thermally favorable microsites from a distance. In preliminary Y-maze trials, snakes were able to locate thermally favorable microsites more often than predicted by chance (p < 0.01, sign test). Thus, Western Diamondback Rattlesnakes (Crotalus atrox) may have the ability to use the thermal sense to locate thermally favorable microsites in the absence of other cues.