Behavioral Ecology and Sociobiology

, Volume 45, Issue 6, pp 430–436 | Cite as

Sexual selection, feather breakage and parasites: the importance of white spots in the tail of the barn swallow (Hirundo rustica)

  • Mati Kose
  • Anders Pape Møller


The long outermost tail feathers of barn swallows Hirundo rustica have white spots that are larger in males than in females and in adults than in juveniles. Spot size increases with age among adults and is positively correlated with tail length. We tested the functional significance of these white spots by randomly assigning males to either of three groups during spring: (1) subjected to a considerable reduction in the size of all spots using a black permanent pen; (2) subjected to a small reduction in the size of all spots; or (3) a control group with no reduction. Experimental treatment significantly affected the total number of offspring produced per season: breeding tended to be delayed and second broods were less frequent after a considerable reduction in the size of the males' tail feather spots. White parts of feathers lacking melanin were more often found to be the site of feather breakage than the melanised parts of similar width. Furthermore, white tail spots were the preferred feeding site of feather-eating Mallophaga and, since long-tailed males have fewer Mallophaga than short-tailed males, long-tailed males may pay a lower cost for their large white tail spots than short-tailed males. Hence, the cost of increased risk of feather breakage at white tail spots and the non-random distribution of feather lice among individuals will render tail spots a reliable signal of phenotypic quality.

Key words Barn swallows Costs of secondary sexual characters Hirundo rustica Mallophaga Melanin Reliable signalling White tail spots 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Mati Kose
    • 1
  • Anders Pape Møller
    • 2
  1. 1.Estonian Institute of Zoology and Botany, Riia 181 EE-2400 Tartu, Estonia, and Department of Zoology and Hydrobiology, Tartu University Riia 181, EE-2400 Tartu, EstoniaEE
  2. 2.Laboratoire d'Ecologie, CNRS URA 258 Université Pierre et Marie Curie, Bât. A, 7ème étage 7 quai St. Bernard, Case 237, F-75252 Paris Cedex 05, France e-mail:, Tel.:+33-1-44272594 Fax: +133-1-44273516FR

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