Extra-pair paternity and male badge size in the House Sparrow

Females of socially monogamous bird species frequently accept or solicit co pulations with males other than their social mate. It has been proposed tha t in so doing females either gain direct benefits such as increased likelih ood of fertilization in the event of their social mate being unable to prov ide sufficient sperm, or indirect (genetic) benefits for their offspring, e .g. 'good genes' from extra-pair partners of higher genetic quality than th eir own mate. Male ornaments such as elongated feathers and patches of colo ured feathers are thought to act as visual cues to male quality. In this st udy we have used single-locus DNA profiling of two House Sparrow Passer dom esticus populations to test the 'good genes' hypothesis prediction that mal es of low quality a ill be cuckolded most frequently. Both intra- and extra -pair mate choice is influenced by the size of the male's black bib which m ay be indicative of male quality. Contrary to the 'good genes' prediction, small-bibbed males were not cuckolded more frequently in either population. Furthermore, none of the measured breeding parameters or female characteri stics correlated with the occurrence of cuckoldry.