Meeting Abstract
Recent studies of various gliding organisms including frogs, ants, squirrels, colugos, snakes and partially fledged birds uncovered a wide range of non-equilibrium behaviors. These indicated that all gliding animals in air must be able to stabilize, steer or maneuver to avoid injury and land at intended locations with a manageable kinetic energy. The ability of gliding animals to meet the above requirements may be more biologically relevant than factors directly relevant to equilibrium gliding such as lift to drag ratio, but the breadth of capabilities among species remains largely unknown. Unlike other limbed gliding vertebrates, the gliding lizard (Draco) uses a wing not derived from appendages but still must meet all the above requirements for successful gliding. This begs the question of how is this behavior achieved and how it compares on various performance scales to other gliding taxa. We recorded 3D tracks of natural glides from a wild population of Draco dussumieri in the field using a non-invasive multi-camera videography scheme. Initial analysis and observations reveal no equilibrium glides. Instead, we found a wide range of glide angles (-64 to 20°), glide ratios of ~0.9-1.6 and dramatic body orientation changes during glides, from sharply pitched down to pitched upward. These produced continuously changing kinematic profiles for velocity (peak ~6.3 ms-1), acceleration (peak av~13 ms-2, peak ah~8.3 ms-2), energy, and aerodynamic parameters (lift, drag, angle of attack). Lateral and vertical maneuvers were also quantified during glides. These results provide the first look at time-resolved freely maneuvering glide trajectories in the field, revealing maneuvering and non-equilibrium control capabilities in Draco in realistic settings.
