EXTRAPAIR PATERNITY IN HOODED WARBLERS

We examined the role of extrapair fertilizations (EPFs) in the mating system of the hooded warbler (Wilsonia citrina), a monogamous songbird . DNA fingerprinting revealed that 8 of 17 (47%) females had extrapair young in their first or second brood, and 23 of 78 (29%) nestlings we re the result of EPFs. Extrapair young were significantly more likely to occur in first broods than in second broods. The proportion of EPFs within a brood was strongly bimodal among broods: nests had 50% or mo re extrapair young or none. In seven of eight broods where EPFs occurr ed, an adjacent male neighbor was identified as the actual father. Mal e-like coloration in females did not reduce the likelihood of having e xtrapair young. Females with extrapair young did not receive less pare ntal care from their mates. All males who obtained EPFs were mated to fertile females or were feeding offspring at the time they most likely mated with the extrapair female. Our results are consistent with the female control hypothesis, which predicts that females benefit from ex trapair copulations (EPCs) and have some control over which males, if any, obtain EPCs. However, we could not reject the alternative hypothe sis that some male neighbors are particularly dominant and aggressive during EPC attempts, so females accept these EPCs to minimize costs.