Ecological conditions during winter affect sexual selection and breeding in a migratory bird

Nicola Saino, Tibor Szép, Roberto Ambrosini, Maria Romano, Anders Pape Møller

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134 Citations (Scopus)


Populations of migratory birds have undergone marked declines, although the causes and mechanisms remain unknown. Because environmental effects on population dynamics are mediated by the effects of ecological factors on individuals, understanding changes in individual phenotypes in response to ecological conditions is key to understanding population trends. We show that breeding individuals of a declining population of trans-Saharan migratory barn swallows, Hirundo rustica, were affected by environmental conditions, as estimated from the normalized difference vegetation index (NDVI), reflecting primary production, in their winter quarters. The breeding dates of the same individuals in consecutive breeding seasons were advanced and clutch sizes were larger after winters with high NDVI in the winter quarters. Feather moult was also affected by winter conditions, with consequences for male sexual attractiveness. Length of tail ornament was positively correlated with NDVI during the previous winter, and males with large tail ornaments reproduced earlier and had larger clutches. The mean annual breeding date of the population was earlier and breeding success was increased after favourable winters, but this result was mainly determined by a single winter with very low NDVI. Thus, ecological conditions in Africa influence individual performance and productivity in a barn swallow population.

Original languageEnglish
Pages (from-to)681-686
Number of pages6
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1540
Publication statusPublished - Apr 7 2004


  • Carry-over effects
  • Connectivity
  • Migration
  • Normalized difference vegetation index
  • Phenotypic plasticity

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

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