Male Morphology and Behavior Correlate with Reproductive Success in the American Redstart (Setophaga ruticilla)

In a population of American redstarts (Setophaga ruticilla), we determined whether a relationship exists between seasonal reproductive success (RS) and a variety of male and female morphological and behavioral characters including plumage and male song. Adult males differ dramatically in plumage from yearling males and also exhibit variable amounts of black on their breast (bib size). Adult males were more successful than yearlings in terms of the number of eggs laid by their females. Among adult males, those with smaller bibs (less black) had females that laid more eggs, and produced more hatchlings and more fledglings. We found no evidence to indicate that this result was a consequence of territory quality. We examined a number of features of song but none alone was a predictor of RS; however, one song feature (rare repeat song) correlated with bib size. When bib size and rare repeat song were analyzed simultaneously, both were found to relate to RS. No female features were predictors of RS, but females arriving earlier at the breeding site mated with males with smaller bibs. The evidence is consistent with the view that plumage of redstarts may be used as a basis for female choice.