Edge detection in landing budgerigars (Melopsittacus undulatus)

Bhagavatula, Partha, Claudianos, Charles, Ibbotson, Michael and Srinivasan, Mandyam (2009) Edge detection in landing budgerigars (Melopsittacus undulatus). PLoS One, 4 10: e7301.1-e7301.10. doi:10.1371/journal.pone.0007301

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Author Bhagavatula, Partha
Claudianos, Charles
Ibbotson, Michael
Srinivasan, Mandyam
Title Edge detection in landing budgerigars (Melopsittacus undulatus)
Formatted title
Edge detection in landing budgerigars (Melopsittacus undulatus)
Journal name PLoS One   Check publisher's open access policy
ISSN 1932-6203
Publication date 2009-10-07
Sub-type Article (original research)
DOI 10.1371/journal.pone.0007301
Open Access Status DOI
Volume 4
Issue 10
Start page e7301.1
End page e7301.10
Total pages 10
Editor Christopher Surridge
Place of publication San Francisco, CA, U.S.A.
Publisher Public Library of Science
Collection year 2010
Language eng
Subject C1
080106 Image Processing
010202 Biological Mathematics
970106 Expanding Knowledge in the Biological Sciences
970109 Expanding Knowledge in Engineering
170112 Sensory Processes, Perception and Performance
Formatted abstract
Background: While considerable scientific effort has been devoted to studying how birds navigate over long distances, relatively little is known about how targets are detected, obstacles are avoided and smooth landings are orchestrated. Here we examine how visual features in the environment, such as contrasting edges, determine where a bird will land.

Methodology/Principal Findings:
Landing in budgerigars (Melopsittacus undulatus) was investigated by training them to fly from a perch to a feeder, and video-filming their landings. The feeder was placed on a grey disc that produced a contrasting edge against a uniformly blue background. We found that the birds tended to land primarily at the edge of the disc and walk to the feeder, even though the feeder was in the middle of the disc. This suggests that the birds were using the visual contrast at the boundary of the disc to target their landings. When the grey level of the disc was varied systematically, whilst keeping the blue background constant, there was one intermediate grey level at which the budgerigar's preference for the disc boundary disappeared. The budgerigars then landed randomly all over the test surface. Even though this disc is (for humans) clearly distinguishable from the blue background, it offers very little contrast against the background, in the red and green regions of the spectrum.

We conclude that budgerigars use visual edges to target and guide landings. Calculations of photoreceptor excitation reveal that edge detection in landing budgerigars is performed by a color-blind luminance channel that sums the signals from the red and green photoreceptors, or, alternatively, receives input from the red double-cones. This finding has close parallels to vision in honeybees and primates, where edge detection and motion perception are also largely color-blind.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article no. e7301, pp.1-10

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Created: Wed, 18 Nov 2009, 15:11:46 EST by Debra McMurtrie on behalf of Queensland Brain Institute