Signatures of Motion: Decomposition of Adaptive Morphing Flight in Harris' Hawks

Abstract

Birds outperform engineered aircraft with exceptional maneuverability, achieved by continuously morphing their wings and tails in flight. Yet the coordination and control of these shape changes remain poorly understood. Using high-speed motion capture of Harris hawks, we analyzed 289,000 wing-tail configurations in over 2000 flights and identified four fundamental shape change patterns, or "morphing shape modes", that capture over 96% of wing and tail variation. Further modes reflect subtle but critical fine-tuning, in line with known morphing control mechanics. The hawks morphing flight is highly structured yet flexible, and we find adaptive strategies in response to obstacles, added weight, with maturity, while each individual shows unique morphing signatures. Our approach defines a shared kinematic morphospace for hawk flight, and more broadly a framework that enables future comparative biomechanics, bio-inspired design, and for interpreting high-dimensional natural motion.