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Optic flow helps explain gulls’ altitude control over seas

Optic flow helps explain gulls’ altitude control over seas

Authors :
Thomas J. Evans
Olivier Duriez
Susanne Åkesson
Judy Shamoun-Baranes
Franck Ruffier
Anders Hedenström
Serres
Publication Year :
2019
Publisher :
Cold Spring Harbor Laboratory, 2019.

Abstract

For studies of how flying animals control their flight, seabirds are of particular interest to track with a biologger because they forage offshore where the visual environment can be simply modeled by a flat world textured by waves. This study suggests that optic flow can explain gull’s altitude control over seas. In particular, a new flight model that includes both energy and optical invariants (called theventral optic flow regulation) explain the dynamics of gulls’ altitude control during offshore takeoff and cruising flight. A linear statistical model applied to 352 flights from 16 individual lesser black backed gulls (Larus fuscus) gave a strong correlation between wind assistance and gulls’ altitude. Thereafter, an optic flow-based flight model was applied to 18 offshore takeoff flights from 1. individual gulls. By introducing an upper limit in climb rate in a non-linear first order parametric model on the gull’s elevation dynamics, coupled with an optic-flow set-point, the predicted altitude gives an optimized fit factor value of 63% on average (min value: 30%, max value: 83%) with respect to GPS data. We conclude that the optic-flow regulation principle (here running close to 25°/s) allows gulls to adjust their altitude over sea without having to directly measure their current altitude.

Details

Language :
English
Database :
OpenAIRE
Accession number :
edsair.doi.dedup.....5ca384ff297c25a5ec774d320a31bec2
Full Text :
https://doi.org/10.1101/569194