Meeting Abstract

P3.146  Monday, Jan. 6 15:30  The effects of gap distance and substrate compliance on the biomechanics of jumping in gray squirrels (Sciurus carolinensis) BYRNES, G*; SPENCE, AJ; MARTINO, B; HILT, M; WILSON, AM; Siena College; Royal Veterinary College; Siena College; Siena College; Royal Veterinary College gbyrnes@siena.edu

The structure of arboreal environments poses many challenges to animal locomotion including unsteady, compliant branches and large open spaces between adjacent branches. The ability to move among the terminal branches and cross these gaps by leaping can greatly reduce transit distances within the canopy. Branch compliance potentially enables animals to store elastic strain energy in the environment to increase leaping performance. However, animals must delay leg extension until the branch is ascending back to its resting position to take advantage of stored external energy. We investigated the effects of gap distance and branch compliance on the biomechanics of jumping in the gray squirrel (Sciurus carolinensis). Both gap distance and branch compliance had significant effects on the kinematics and kinetics of leaping in squirrels. Squirrels jumped with higher peak forces and larger impulses when crossing larger gaps. In addition, extension of both the proximal and distal limb joints increased with increasing gap distance. Peak forces decreased with increasing branch compliance while both joint extension and the time over which joint extension occurred increased with increased compliance. These preliminary data suggest that squirrels are capable of delaying leg extension to coincide with branch recoil during jumping, potentially recovering some of the strain energy stored in the branch. Squirrels also use behavioral mechanisms to limit the magnitude of branch deflection they experience during leaping.