Tim E. Higham

I am interested in how animals move in their natural habitat. To do this, I study how various habitat features such as incline and turn angle affect the in vivo muscle activity, three-dimensional hindlimb kinematics, and the performance of animals in the laboratory. Arboreal habitats are characterized by perches that vary considerably in their orientation and thus provide a setting that can be mimicked in the laboratory using artificial perches.

EFFECTS OF INCLINE ON THE LOCOMOTION OF CHAMELEONS
My current project analyzes the effects of inclines on both the kinematics and in vivo muscle activity in the hindlimb of the veiled chameleon, Chamaeleo calyptratus. Chameleons have several highly specialized morphological traits including independently moving eyes, a laterally compressed body, zygodactylous limbs, and a projectile tongue. Since the majority of chameleons are arboreal, moving on perches of variable incline is inevitable in their natural habitat. I use two high-speed video cameras to provide simultaneous lateral and dorsal views of the animal suitable for studying the three-dimensional kinematics of the lizards moving up and down perches of varying inclines. I also use electromyography to measure the activity in several hindlimb muscles simultaneously. Integrating the kinematic and electromyographic data clarifies how inclines affect the movement and function of the hindlimbs in chameleons.

EFFECTS OF TURNING ANGLE ON THE LOCOMOTION OF ANOLES
Networks of perches in arboreal habitats force animals that move on them to maneuver. I previously analyzed the effects of turning angle on the locomotion of three species of Anolis lizards from Jamaica by manipulating the turning angle of artificial perches in the laboratory. We expected the performance of all of the lizards to decrease as the turning angle increased, but the detrimental effects of turn angle on performance depended on the species and the measure of performance. For example, Anolis grahami was the only species not affected by turn angle, but this was only when net (pause time excluded) velocity was the measure of performance. Another intriguing result was how the species maneuvered around the turns. All three of the lizard species frequently jumped when confronted with a 90^o turn angle. Accompanying the jumps was an increase in frequency, as well as duration, in pausing both before and following the jumps. Thus, maneuverability not only involves turning speed, but is complicated by additional behaviors such as jumping and intermittent locomotion. See publication (full text Adobe 3 .pdf format 258Kb).

Tim E. Higham M.S. student

Address: Tim E. Higham Department of Biological Sciences, ML006 University of Cincinnati Cincinnati, Ohio 45221-0006 Telephone: (513) 556-5696 FAX: (513) 556-5299 Email: highamte@email.uc.edu