Post-mating sexually selected signals are expected to indicate parental quality. The good parent model assumes that expression of the sexual character positively reflects parental ability, resulting in a potential link between the exaggeration of the character and nestling-fitness traits. We...

Among bird species in which males contribute to nest building, sexual selection has favored larger nests. I investigated determinants of nest size in the barn swallow Hirundo rustica and how nest size changed during the period 1977--2003, when tail length (a male secondary sexual character)...