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Optic flow cues help explain altitude control over sea in freely flying gulls

Serres, Julien R. ; Evans, Thomas J. LU ; Åkesson, Susanne LU ; Duriez, Olivier ; Shamoun-Baranes, Judy ; Ruffier, Franck and Hedenström, Anders LU (2019) In Journal of the Royal Society, Interface 16(159).
Abstract

For studies of how birds control their altitude, seabirds are of particular interest because they forage offshore where the visual environment can be simply modelled by a flat world textured by waves then generating only ventral visual cues. This study suggests that optic flow, i.e. the rate at which the sea moves across the eye's retina, can explain gulls' altitude control over seas. In particular, a new flight model that includes both energy and optical invariants helps explain the gulls' trajectories during offshore takeoff and cruising flight. A linear mixed model applied to 352 flights from 16 individual lesser black backed gulls (Larus fuscus) revealed a statistically significant optic flow set-point of ca 25° s-1. Thereafter, an... (More)

For studies of how birds control their altitude, seabirds are of particular interest because they forage offshore where the visual environment can be simply modelled by a flat world textured by waves then generating only ventral visual cues. This study suggests that optic flow, i.e. the rate at which the sea moves across the eye's retina, can explain gulls' altitude control over seas. In particular, a new flight model that includes both energy and optical invariants helps explain the gulls' trajectories during offshore takeoff and cruising flight. A linear mixed model applied to 352 flights from 16 individual lesser black backed gulls (Larus fuscus) revealed a statistically significant optic flow set-point of ca 25° s-1. Thereafter, an optic flow-based flight model was applied to 18 offshore takeoff flights from nine individual gulls. By introducing an upper limit in climb rate on the elevation dynamics, coupled with an optic flow set-point, the predicted altitude gives an optimized fit factor value of 63% on average (30-83% in range) with respect to the GPS data. We conclude that the optic flow regulation principle helps gulls to adjust their altitude over sea without having to directly measure their current altitude.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
energy invariant, flight modelling, motion vision, optical invariant, visual neuroscience
in
Journal of the Royal Society, Interface
volume
16
issue
159
pages
1 pages
publisher
The Royal Society of Canada
external identifiers
  • pmid:31594521
  • scopus:85073074544
ISSN
1742-5662
DOI
10.1098/rsif.2019.0486
language
English
LU publication?
yes
id
cdcf3343-895c-405f-8dd1-d9ab69d15421
date added to LUP
2019-10-21 12:17:18
date last changed
2020-09-16 04:33:11
@article{cdcf3343-895c-405f-8dd1-d9ab69d15421,
  abstract     = {<p>For studies of how birds control their altitude, seabirds are of particular interest because they forage offshore where the visual environment can be simply modelled by a flat world textured by waves then generating only ventral visual cues. This study suggests that optic flow, i.e. the rate at which the sea moves across the eye's retina, can explain gulls' altitude control over seas. In particular, a new flight model that includes both energy and optical invariants helps explain the gulls' trajectories during offshore takeoff and cruising flight. A linear mixed model applied to 352 flights from 16 individual lesser black backed gulls (Larus fuscus) revealed a statistically significant optic flow set-point of ca 25° s-1. Thereafter, an optic flow-based flight model was applied to 18 offshore takeoff flights from nine individual gulls. By introducing an upper limit in climb rate on the elevation dynamics, coupled with an optic flow set-point, the predicted altitude gives an optimized fit factor value of 63% on average (30-83% in range) with respect to the GPS data. We conclude that the optic flow regulation principle helps gulls to adjust their altitude over sea without having to directly measure their current altitude.</p>},
  author       = {Serres, Julien R. and Evans, Thomas J. and Åkesson, Susanne and Duriez, Olivier and Shamoun-Baranes, Judy and Ruffier, Franck and Hedenström, Anders},
  issn         = {1742-5662},
  language     = {eng},
  number       = {159},
  publisher    = {The Royal Society of Canada},
  series       = {Journal of the Royal Society, Interface},
  title        = {Optic flow cues help explain altitude control over sea in freely flying gulls},
  url          = {http://dx.doi.org/10.1098/rsif.2019.0486},
  doi          = {10.1098/rsif.2019.0486},
  volume       = {16},
  year         = {2019},
}