TY - JOUR T1 - Through the eyes of a bird: modelling visually guided obstacle flight JF - J R Soc InterfaceJ R Soc InterfaceJ R Soc Interface Y1 - 2014 A1 - Lin, H. T. A1 - Ros, I. G. A1 - Biewener, A. A. KW - *Flight, Animal KW - *Models, Biological KW - *Visual Perception KW - Animals KW - Birds KW - Columbidae/*physiology KW - Depth Perception KW - Eye KW - Homing Behavior AB - Various flight navigation strategies for birds have been identified at the large spatial scales of migratory and homing behaviours. However, relatively little is known about close-range obstacle negotiation through cluttered environments. To examine obstacle flight guidance, we tracked pigeons (Columba livia) flying through an artificial forest of vertical poles. Interestingly, pigeons adjusted their flight path only approximately 1.5 m from the forest entry, suggesting a reactive mode of path planning. Combining flight trajectories with obstacle pole positions, we reconstructed the visual experience of the pigeons throughout obstacle flights. Assuming proportional-derivative control with a constant delay, we searched the relevant parameter space of steering gains and visuomotor delays that best explained the observed steering. We found that a pigeon's steering resembles proportional control driven by the error angle between the flight direction and the desired opening, or gap, between obstacles. Using this pigeon steering controller, we simulated obstacle flights and showed that pigeons do not simply steer to the nearest opening in the direction of flight or destination. Pigeons bias their flight direction towards larger visual gaps when making fast steering decisions. The proposed behavioural modelling method converts the obstacle avoidance behaviour into a (piecewise) target-aiming behaviour, which is better defined and understood. This study demonstrates how such an approach decomposes open-loop free-flight behaviours into components that can be independently evaluated. VL - 11 SN - 1742-5662 (Electronic)1742-5662 (Linking) N1 - Lin, Huai-TiRos, Ivo GBiewener, Andrew AengResearch Support, U.S. Gov't, Non-P.H.S.England2014/05/09 06:00J R Soc Interface. 2014 May 8;11(96):20140239. doi: 10.1098/rsif.2014.0239. Print 2014 Jul 6. U2 - 4032538 JO - Journal of the Royal Society, Interface / the Royal SocietyJournal of the Royal Society, Interface / the Royal Society ER -