Meeting Abstract

44.6  Wednesday, Jan. 5  Three-dimensional trajectories affect gap bridging in brown tree snakes (Boiga irregularis) BYRNES, G.*; JAYNE, B. C.; University of Cincinnati; University of Cincinnati byrnesgt@ucmail.uc.edu

Arboreal environments have complex networks of branches separated by large open spaces and the ability to cross these gaps can greatly shorten the route of an animal through the environment. Many snakes are arboreal and their elongate bodies are well suited to crossing gaps. However, extending a large unsupported portion of the body over a gap could result in either toppling off the branch or buckling of the body, therefore crossing large gaps can be a highly demanding task. We investigated the ability of a highly arboreal snake, the brown tree snake (Boiga irregularis), to cross gaps in which the location of the destination perch varied both in the vertical and horizontal planes. Snakes were able to cross larger gaps as the vertical component of the gap distance increased and as a result, crossed the smallest gaps within the horizontal plane. These results suggests that producing sufficient muscular force to prevent buckling may limit gap distance because when crossing gaps in the horizontal plane, gravity acts at a greater horizontal distance from the point of support for a given gap distance. In addition, when the destination perch was oriented at an angle to the long axis of the initial perch, gap distances decreased as a result of the inability of snakes to maintain balance due to the large pitching moment, especially while crossing horizontal or uphill gaps. In most cases, the snakes extended and crawled across a gap at near constant speed, however in some cases snakes used rapid dynamic movements to extend their gap crossing range. Perhaps these dynamic movements are a common and shared character of many arboreal snakes that could have lead to more sophisticated aerial behavior in snakes.