FLUCTUATING ASYMMETRY AND MATE CHOICE IN PARADISE WHYDAHS, VIDUA-PARADISAEA - AN EXPERIMENTAL MANIPULATION

It has been suggested that the symmetry of sexually selected characters may be assessed by conspecifics in the context of mate choice. The length symmetry of the long ornamental tail feathers of male paradise whydahs was manipulated in a pair-wise mate-choice aviary experiment to test whether female paradise whydahs preferred symmetrical male ornaments. Asymmetrical tails were produced by elongating one rectrix and shortening the other so that the tail had the same average length and area as symmetrical model tails, but with an asymmetry of 15%. Female paradise whydahs did not prefer the symmetrical tail treatments and instead preferred males when they had the asymmetrical treatment, possibly because asymmetrical tails appeared longer. Manipulating tail asymmetry had no detectable influence on male behaviour. These results are not consistent with the findings of other studies that show male symmetry is preferred by females and suggest that the issue of how birds perceive the length of asymmetrical tails may be crucial for ornament manipulation studies.