Meeting Abstract

69.5  Tuesday, Jan. 6  How does a small arboreal mammal use its tail to maintain its balance while traveling on tree branches? LAMMERS, A.R.*; ZURCHER, U.; Health Sciences Dept., Cleveland State University, Ohio; Physics Dept., Cleveland State University, Ohio a.Lammers13@csuohio.edu

Animals which travel on tree branches must avoid toppling from these narrow substrates because a fall may be energetically expensive or cause injury or death. Changing footfall patterns and speed, crouching to bring the center of mass closer to the substrate, and using the tail as a counterbalance are a few examples of mechanisms that an animal might use to maintain balance during locomotion. The tail might be used as a simple counterweight so that the animals weight is balanced over the narrow branch. It is also possible that the tails movement is important to counterbalance the bodys momentum in the mediolateral axis. We sought to quantify the means by which the tail was used during arboreal locomotion in the Siberian chipmunk (Tamias sibiricus). This small quadrupedal mammal is proficient at arboreal and terrestrial locomotion. Its tail is approximately the same length as the head and body length combined, and it appears that the tail is used in some way as a counterbalance. We trained the chipmunks to run across an arboreal trackway about half the diameter of the animals body. Part of the trackway was instrumented to measure torque around the long axis of the branch and substrate reaction forces. We used high speed video to measure the position of the body and tail, and the contact locations of the hands and feet as the moved across the branch. Kinetic data collected from the instrumented trackway provide a way of quantifying the degree to which the animals were off-balance during a trial. Data are being collected as of this writing; we hypothesize that both the position and the movement of the tail will contribute to balancing the animal on a narrow arboreal trackway.