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Published February 6, 2017 | Supplemental Material + Published
Journal Article Open

Rules to fly by: pigeons navigating horizontal obstacles limit steering by selecting gaps most aligned to their flight direction

Abstract

Flying animals must successfully contend with obstacles in their natural environments. Inspired by the robust manoeuvring abilities of flying animals, unmanned aerial systems are being developed and tested to improve flight control through cluttered environments. We previously examined steering strategies that pigeons adopt to fly through an array of vertical obstacles (VOs). Modelling VO flight guidance revealed that pigeons steer towards larger visual gaps when making fast steering decisions. In the present experiments, we recorded three-dimensional flight kinematics of pigeons as they flew through randomized arrays of horizontal obstacles (HOs). We found that pigeons still decelerated upon approach but flew faster through a denser array of HOs compared with the VO array previously tested. Pigeons exhibited limited steering and chose gaps between obstacles most aligned to their immediate flight direction, in contrast to VO navigation that favoured widest gap steering. In addition, pigeons navigated past the HOs with more variable and decreased wing stroke span and adjusted their wing stroke plane to reduce contact with the obstacles. Variability in wing extension, stroke plane and wing stroke path was greater during HO flight. Pigeons also exhibited pronounced head movements when negotiating HOs, which potentially serve a visual function. These head-bobbing-like movements were most pronounced in the horizontal (flight direction) and vertical directions, consistent with engaging motion vision mechanisms for obstacle detection. These results show that pigeons exhibit a keen kinesthetic sense of their body and wings in relation to obstacles. Together with aerodynamic flapping flight mechanics that favours vertical manoeuvring, pigeons are able to navigate HOs using simple rules, with remarkable success.

Additional Information

© 2016 The Author(s). Published by the Royal Society. One contribution of 19 to a theme issue 'Coevolving advances in animal flight and aerial robotics'. We thank S. Gagliardi, G. T. Clifton and C. D. Williams for help with data collection. We further thank two anonymous reviewers for their suggestions. This research was supported by a grant from the Office of Naval Research (ONR, N0014-10-1-0951) to A.A.B. Authors' contributions: I.G.R., H.T.L. and A.A.B. conceived the study. I.G.R. and A.A.B. designed the study. I.G.R. and P.S.B. performed the experiments and processed the data. I.G.R. performed the statistics and analyses for the behavioural modification. H.T.L. performed the analyses comparing V.O. and H.O. flights, and implemented the flight guidance models. I.G.R., H.T.L. and A.A.B. wrote the manuscript with critical input from P.S.B. Data availability: Data are available at: https://figshare.com/s/667dbcb6a65adf7b249e. We declare we have no competing interests.

Attached Files

Published - 20160093.full.pdf

Supplemental Material - dataFigShare.zip

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Additional details

Created:
August 19, 2023
Modified:
October 24, 2023