Meeting Abstract
Gliding animals undertake a series of complex aerodynamic and morphological adjustments in order to execute a transition from perching or resting to gliding. Take-off requires the animal to generate adequate thrust, deploy its wing and correct its body orientation immediately after launching itself towards the landing target. In order to accomplish this, the animal uses a combination of limb and tail movements along with dynamic wing and body morphing. We used two cameras recording at 240 Hz to film take-offs in a wild population of flying lizards, Draco dussumieri, from vertical tree surfaces for a glide distance of 5.5 m. We tracked body points including the head, limbs, wings, posterior end and tail in 3D to study take-off biomechanics in the field. Take-off was initiated by the lizard rotating from a vertical to horizontal position on the tree trunk and using its hind limbs to thrust itself in the direction of the landing tree accelerating at ~9 ms-2 and reaching a velocity of ~2.5 ms-1 by the time of complete wing deployment. Dracos are unique among gliding animals in possessing a head-mounted canard along with a main wing membrane which is supported by ribs on either side. Deployment of the canard and main wing began immediately after launch with canards being fully extended first at ~0.05 s followed by wing in ~0.10 s. The main wing was extended and held in position independently of the limbs during take-off. The forelimbs were extended from the body and eventually held parallel to the leading edge of the wing with the wrists resting on its top surface, potentially forming a leading edge slot. We observed pronounced tail movement during the take-off phase along with changes in body roll, pitch and yaw suggesting a role in controlling body orientation. These observations provide a first detailed look at Draco take-off in a natural setting.
