Meeting Abstract
Pheromones produced by female red-sided garter snakes (Thamnophis sirtalis parietalis) are the primary reproductive cue for courting males. Some males (she-males) also produce this pheromone and are actively courted by other males, but the functional significance of this is unknown. Body temperature (Tb) has been a suggested secondary cue for reproductive state because newly emerged virgin females are cold when they leave the den. Clarifying role Tb plays in female attraction will improve our understanding of the competitive scramble mating system exhibited by red-sided garter snakes. In this study, we tested whether or not female and she-male attractiveness to courting male snakes changes with Tb. We collected virgin (VF) and non-virgin (NVF) female, and she-male (SM) and unattractive male (UM) snakes in Manitoba, Canada. All females, SM, and UM were cooled to ~8°C and individually placed in courtship arenas with 50 courting males. During courtship trials we recorded changes in Ts over time using infrared thermography and noted whether or not snakes were courted over a range of Ts. All VFs (n=8) and SMs (n=10) were courted whereas all NVFs (n=9) and UMs (n=10) were not courted. Ts of females (VF & NVF) and males (SM & UM) rapidly increased and stabilized at ~30°C within 10 minutes, and male courtship remained constant over all measured Ts. Warming rates did not differ between VF and NVF (F=0.04, P=0.84) or between SM and UM (F=0.71, P=0.40). Cold Ts could serve as an initial indicator that a female is virgin, but since Ts rises quickly would at best be a short-term cue. Intense courtship at warm Ts suggests that female pheromones are the primary determiner of female and she-male attractiveness.
