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High resolution of colour vision, but low contrast sensitivity in a diurnal raptor

  • Simon Potier
  • Mindaugas Mitkus
  • Almut Kelber
Publishing year: 2018-08-29
Language: English
Publication/Series: Proceedings of the Royal Society B: Biological Sciences
Volume: 285
Document type: Journal article
Publisher: Royal Society

Abstract english

Animals are thought to use achromatic signals to detect small (or distant) objects and chromatic signals for large (or nearby) objects. While the spatial resolution of the achromatic channel has been widely studied, the spatial resolution of the chromatic channel has rarely been estimated. Using an operant conditioning method, we determined (i) the achromatic contrast sensitivity function and (ii) the spatial resolution of the chromatic channel of a diurnal raptor, the Harris's hawk Parabuteo unicinctus The maximal spatial resolution for achromatic gratings was 62.3 c deg-1, but the contrast sensitivity was relatively low (10.8-12.7). The spatial resolution for isoluminant red-green gratings was 21.6 c deg-1-lower than that of the achromatic channel, but the highest found in the animal kingdom to date. Our study reveals that Harris's hawks have high spatial resolving power for both achromatic and chromatic vision, suggesting the importance of colour vision for foraging. By contrast, similar to other bird species, Harris's hawks have low contrast sensitivity possibly suggesting a trade-off with chromatic sensitivity. The result is interesting in the light of the recent finding that double cones-thought to mediate high-resolution vision in birds-are absent in the central fovea of raptors.


  • Zoology
  • colour vision
  • contrast sensitivity
  • foraging
  • raptors
  • spatial resolution


  • Lund Vision Group
  • ISSN: 1471-2954
Simon Potier
E-mail: simon [dot] potier [at] biol [dot] lu [dot] se

Postdoctoral fellow

Functional zoology


Research group

Lund Vision Group


Bird visual ecology

Postdoc host

Almut Kelber

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