DNA fingerprinting reveals relation between tail ornaments and cuckoldry in barn swallows, Hirundo rustica

In an experimental study in Denmark, it was previously found that male barn swallows (Hirundo rustica) with elongated tail streamers obtained an apparent fitness advantage through earlier pairing, an increased frequency of second clutches, and higher total reproductive success per season. In a parallel study of five barn swallow colonies in Ontario, Canada, we also found that elongated males paired earlier and thus were apparently preferred by …