Meeting Abstract

88.5  Sunday, Jan. 6  Kinetics of locomotion on arboreal and terrestrial substrates in Siberian chipmunks (Tamias sibiricus) LAMMERS, A.R.*; DORSEY, E.J.; Cleveland State University, Ohio; Cleveland State University, Ohio a.Lammers13@csuohio.edu

Traveling on tree branches and twigs is common among mammals, but until recently most studies concentrated on primates. With work carried out on gray short-tailed opossums, rats, and red squirrels (Schmidt & Fischer 2010; Schmidt 2011), it is possible to begin generalizing about differences in arboreal locomotor biomechanics between primates and other mammals. We trained five Siberian chipmunks to run on 2 m long trackways – one with a flat surface to simulate a terrestrial surface, and the other cylindrical (2 cm diameter) to simulate an arboreal substrate. We instrumented a portion of each trackway to measure substrate reaction force from the limbs on the animals’ right side. The force pole was split so that the right side of the cylinder measured force while the left side was un-instrumented. Peak vertical force and vertical impulse were higher in forelimbs than hindlimbs. Peak vertical force was reduced on the arboreal track. These patterns are consistent with other non-primate mammals traveling on arboreal substrates. Furthermore, the reduction in peak vertical force on arboreal supports is consistent across mammals. If reducing branch oscillation is the reason for this behavior, then the adaptation probably occurred early in the mammalian radiation. Forelimbs were net braking and hindlimbs net propulsive; there were no differences in net fore-aft impulses between arboreal and terrestrial trackways. Laterally-directed substrate reaction impulse was higher on the arboreal supports. On the narrow arboreal cylinder, the chipmunks squeeze the branch between right and left hands or feet, providing a stable grip. This is consistent with the other non-primate mammals from which mediolateral forces were measured from individual limbs.