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Behavioral Ecology and Sociobiology

, Volume 42, Issue 1, pp 71–76 | Cite as

Bilateral symmetry and social dominance in captive male red-winged blackbirds

  • Kevin W. Dufour
  • Patrick J. Weatherhead
Article

Abstract

There has been much recent interest in subtle departures from perfect symmetry in bilaterally paired morphological characters, and the extent to which such departures reflect aspects of individual quality. We used data from aviary contests involving pairs of wild-caught male red-winged blackbirds (Agelaius phoeniceus) to test the hypothesis that comparatively symmetrical males are disproportionately successful in intra-sexual competition for food. Although paired contestants showed clear and consistent differences in competitive ability, there was no indication that symmetrical males were competitively superior. Winners and losers of aviary contests were indistinguishable based on asymmetry measures made on each of four bilateral characters (tarsus length, wing chord, and two epaulet dimensions), and for a fifth character (length of outer retrix), asymmetry differences, though significant, occurred in the direction opposite to that predicted. Furthermore, there was no detectable association between male competitive ability and a composite measure that combined asymmetry information across all five characters. Our results, in combination with those of several other recent avian studies, suggest that symmetry is generally a poor predictor of social dominance in birds. This finding is inconsistent with the proposal that symmetry provides a readily obtained, reliable measure of phenotypic quality.

Key words Bilateral symmetry Dominance Intra-sexual competition Red-winged blackbird 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Kevin W. Dufour
    • 1
  • Patrick J. Weatherhead
    • 1
  1. 1.Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada Fax: (613) 520-4497; e-mail: kdufour@ccs.carleton.caCA

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