Meeting Abstract
P3.137 Monday, Jan. 6 15:30 Biomechanic effects of the coordination of head bobbing and footfalls during locomotion in quail NYAKATURA, J.A.*; ANDRADA, E.; Friedrich-Schiller-Universität, Jena, Germany; Friedrich-Schiller-Universität, Jena, Germany john.nyakatura@uni-jena.de
Head bobbing of birds is considered a primarily opto-motoric phenomenon that improves vision. It comprises of a hold and a thrust phase and has been shown to be coordinated with footfalls during locomotion of many birds, including quail. During terrestrial locomotion the body’s center of mass (CoMbody) of birds is subjected to rhythmic changes of its potential and kinetic energy. CoMbody energy patterns characteristically change with gait and allow broadly discriminating between walking and running. Without compensation, any vertical oscillations of the trunk potentially conflict demands of vision (i.e., ocular stability). We tested the hypothesis that timing of head bobbing is a means to mitigate the conflicting demands of vision and locomotion using x-ray motion analysis and simulation of quail locomotion. We found significant differences in the timing of head bobbing between gaits that corroborate our hypothesis. Forward thrust of the head (eyes) sets in later in trials with walking (vaulting) mechanics than in trials with running (bouncing) mechanics in concert with expectations based on vertical fluctuations of the body’s potential energy in vaulting and bouncing models. By simulating altered timing of head-body-coordination we further show that the timing limits the vertical displacement of the head and has a compensating effect on the potential energy fluctuation of CoMbody. The first is clearly advantageous for vision, the latter is potentially indicative of an energy saving mechanism during constrained locomotion with necessary head bobbing.
