Meeting Abstract
Targeted leaping across large gaps is a fundamental skill in arboreal environments where errors carry considerable risk. Animals lacking the ability to generate aerodynamic forces move along a ballistic trajectory towards a landing point. The center-of-mass trajectory is predetermined at initial take-off, because animals are unable to make mid-flight corrections. We found that free ranging fox squirrels ( Sciurus niger) jumping from a launching beam to a landing perch, both attached to a wall, selectively established an additional control point mid-leap using a parkour-like wall-jump maneuver. In this maneuver, animals re-oriented some or all of their legs toward the vertical surface, generating substrate reaction forces to alter their trajectory before landing. We hypothesized that squirrels use the wall-jump maneuver for longer leaps. To test this, we systematically varied the horizontal distance between the launching beam and landing perch (0.5, 1.0, 1.5 m). We also varied vertical position (± 20 cm) at each perch distance along an isocline of constant impulse. Squirrels consistently used the wall-jump maneuver for medium and long leaps (ranging 3-5 body lengths), but not for short leaps (about 1.5 body lengths). Vertical variations in perch position did not affect the proportion of trials exhibiting the wall-jump maneuver. When squirrels used the wall-jump maneuver to reach lower perch heights, they generally decelerated during wall contact phase, leading to a reduction of horizontal velocity upon landing. During leaps to level and high height perch positions, the direction of acceleration varied significantly. Future manipulations may allow us to predict possible creative biomechanical solutions to maneuvering in complex environments.
