Differences in color vision make passerines less conspicuous in the eyes of their predators

doi:10.1073/pnas.0409228102

Differences in color vision make passerines less conspicuous in the eyes of their predators

^*Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, S-752 36 Uppsala, Sweden; and ^†Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada V5A 1S6

Edited by Nancy A. Moran, University of Arizona, Tucson, AZ, and approved March 28, 2005 (received for review December 10, 2004)

Abstract

Sexual selection often favors brighter and exaggerated traits, which also increase the risk of detection by predators. Signals that are preferentially conspicuous to conspecifics would reduce the predation cost of signaling and, therefore, might facilitate the evolution of stronger sexual and social signals. This selective signaling is possible if predators and prey have differently tuned sensory systems. By using a retinal model to compare reflectance from the plumages of Swedish songbirds to the reflectance of their natural backgrounds, we found their color badges to be significantly more conspicuous to other songbirds (which have a UV-tuned visual system) than to raptors and corvids (which have a violet-tuned system) in both coniferous and deciduous forests, consistent with an adaptive private communication system.

Footnotes

↵ ‡ To whom correspondence should be addressed at: Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, S-752 36 Uppsala, Sweden. E-mail: anders.odeen{at}ebc.uu.se.
Author contributions: O.H., J.V., and A.Ö. designed research, performed research, contributed new reagents/analytic tools, analyzed data, and wrote the paper.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: VS, violet-sensitive; UVS, UV-sensitive; SWS1/2, first/second shortwave-sensitive opsin.