How important is temperature for strike success of ectotherms? Thermal effects on predator–prey interactions of free-ranging pit vipers (Gloydius blomhoffii)

Abstract

Among various environmental factors, temperature has been considered a main determinant of outcomes of predator–prey interactions involving ectotherms. Although numerous studies have aimed to examine temperature effects on those interactions, few studies have been conducted under fully natural conditions. In this study, we examined the degree to which temperature affects the outcomes of encounters between a Japanese pit viper (Mamushi, Gloydius blomhoffii) and its prey under natural conditions. We continuously recorded ambushing behaviors and body temperatures of these snakes in the field using videography. We found that, over the range of temperatures at which Mamushi hunted, (1) temperature has only limited effects on whether Mamushis initiate a strike at prey and whether strikes successfully hit the prey; (2) prey reactions to strikes, such as whether they dodge the strike or the latency from strike initiation to dodge, are not affected by temperature; and (3) factors such as distance to prey and prey dodging movements are greater determinants than temperature on the outcomes of encounters between free-ranging Mamushi and their prey. Our results suggest that temperature effects on the outcomes of free-ranging snake–prey interactions may be smaller than hitherto considered.