Meeting Abstract
Foraging arboreal birds frequently hop and fly between branches by extending long-jumps with a few wingbeats. Their legs transfer impulse to the branch during takeoff and landing, and their wings transfer impulse to the air to support their bodyweight during flight. To determine the mechanical energy tradeoffs of this bimodal locomotion, we studied how Pacific parrotlets, arboreal generalist birds, transfer impulse during voluntary perch-to-perch flights for a seed reward. Five foraging flight variations were tested inside a novel aerodynamic force platform by varying the inclination and distance between instrumented perches. This setup enables direct, in vivo measurements of both leg and wing forces, which we combined with high-speed kinematics to develop a new bimodal long-jump and flight model. Using this model, we discovered that parrotlets direct their leg impulse to minimize the mechanical energy needed for each flight. The bimodal locomotion model may also lend insight into the evolution of foraging flight, as it shows how even a single proto-wingbeat would have significantly lengthened the long-jump of foraging arboreal dinosaurs. By directing jumps and flapping their wings, both extant and ancestral birds could thus improve foraging effectiveness. Similarly, bimodal robots could also employ these locomotion strategies to traverse cluttered environments more effectively.
