Meeting Abstract
Motor learning is an important complement to pre-determined control because it allows animals to adapt control to changing and/or uncertain bodies and environments. It enables building a movement repertoire specific to local environmental affordances. For many arboreal animals, leaping from a compliant substrate represents a difficult biomechanical challenge in which the animal and the environment are bi-directionally coupled. In principle, these animals may control their leaping dynamics by generating ground reaction forces, creating aerodynamic forces, and by inertial shape change. Previous studies show that many animals modulate their kinematics and kinetics based on substrate compliance, gap distance, and whether they are launching or landing, and may use environmental compliance for energy storage and return. It is unknown whether or how these modifications are learned. Tree squirrels are highly skilled arboreal locomotors, exhibiting long leaps between branches. We presented fox squirrels (Sciurus niger) with a novel compliant diving board-like structure to cross a 75cm gap for a food reward in the field. Five wild fox squirrels (body length 29.6±1.0 cm, mean and s.d.) completed 24 gap crossings. We characterized targeting performance as the distance between the center of mass and the landing platform at the end of the aerial trajectory, and by the number of feet that reached the landing platform. Squirrels demonstrated trial and error motor learning within each day. Both targeting error and missed footholds either remained steady or decreased monotonically during a sequence of two to four trials. Targeting error decreased on average 34±40%. Our next step will be to characterize the biomechanical mechanisms and cues for this highly dynamic learning task.
