Meeting Abstract

P3.162  Sunday, Jan. 6  Branch structure affects perch preference and the performance and behaviors of gap-bridging by the snake, Boiga irregularis LEHMKUHL, A M*; WILLIAMSON, B J ; JAYNE, B C ; University of Cincinnati; University of Cincinnati; University of Cincinnati lehmkuaw@mail.uc.edu

Branch size, shape and orientation have well documented effects on locomotion, such as larger diameter increasing the speed of limbed vertebrates but decreasing the crawling speed of snakes. Despite this detrimental effect, a previous study found that rat snakes prefer larger diameter perches when crossing a gap. Although the maximal distance of gaps that snakes can span has been studied, the effects of perch attributes on gap bridging are unknown. Reaching a larger target requires less precise motor control, leading us to expect that wider destinations may enhance either the speed or distance of crossing a gap. Thus, for the gap bridging of a highly arboreal species of snake (Boiga irregularis), we tested whether different destinations affected perch preference, gap-bridging ability and behavior. B. irregularis usually preferred wider destinations. The snakes readily crawled and gripped our control perch (4.9 cm diameter cylinder with two rows of pegs 10 cm long). Five treatments varied the cylinder diameter, presence of pegs and orientation of destination perch while using the control perch as the supporting perch, and three treatments used the control perch as the destination with three different supporting perches. Differences in the supporting perches did not significantly affect gap bridging performance. However, wider destinations significantly increased both the maximum gap bridging distance and the proportion of snakes using a high speed lunge. Lunging avoided the large torques experienced when snakes crawl slowly and hold their posture the instant before contacting the perch. Thus, wider destinations (which were preferred) elicited a behavior which circumvented a mechanical constraint and in turn improved performance.