How a Small Bird Executes a Sharp Turning Maneuver: A Mechanical Perspective

• Published in: Experimental mechanics 2012-09, Vol.52 (7), p.693-703
• Main Authors: Su, J.-Y., Ting, S.-C., Yang, J.-T.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biomechanics. Biorheology; Biomedical Engineering and Bioengineering; Characterization and Evaluation of Materials; Control; Dynamical Systems; Engineering; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); Lasers; Optical Devices; Optics; Photonics; Physics; Solid dynamics (ballistics, collision, multibody system, stabilization...); Solid Mechanics; Tissues, organs and organisms biophysics; Vibration
• ISSN: 0014-4851; 1741-2765
• DOI: 10.1007/s11340-011-9537-5

In this work, how a small bird (Japanese White-eye, Zosterops japonicus ) executes a sharp turning maneuver is analyzed from a mechanical perspective. A specific type of turning maneuver, termed a ‘hovering turn’, was experimentally identified, which is evidently distinct from the yaw or bank turn that is well documented in the literature. The hovering turn is characterized by a turning radius only about ~1/10 of the wingspan, and requires less than 0.2 s. The reorientation of the bird’s body is invariably preceded by a brief hovering stage during which the elevation angle of the bird increases from 40° to approximately 90°, leading beneficially to a considerable decrease (40% of its maximum) in the moment of inertia of the body against the axis of rotation. The brief hovering is deemed a strategic, preparatory and transitional stage in executing a roll-dominated turn that is efficient and particularly suitable for a small space. The mechanisms pertaining to the hovering turn might provide a useful, biomechanical inspiration to improve the maneuverability of artificial aerial vehicles.