1981/05/01 by Rauno V. Alatalo, Allan Carlson, Arne Lundberg +1 · 1 citation
Agricultural and Biological Sciences · Social Sciences · #Animal Behavior and Reproduction #Plant and animal studies #Evolutionary Game Theory and Cooperation #Ficedula #Biology #Flycatcher #Brood #Altricial #Avian clutch size #Mating #Zoology #Demography #Ecology #Reproduction
paper · doi:10.1086/283756
openalex publication_date 1981/05/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/03
Some males of the pied flycatcher enhance their individual fitness by mating with two females, one of which receives their full support in caring for the brood, while the other is given very little or no aid and therefore, on average, produces a much reduced brood. These so-called secondary females thus have a low fitness. We refute the theories of differential territory quality and of sexy sons to explain the bigamous strategy in this species and argue that the male cheats some females into the role of being secondary. The trick used by the male is maintaining two spatially separate territories (polyterritorialism). We found that secondary females lay fewer eggs and take this as evidence that, at some point, they become "aware" of their true marital status and then, adaptively, reduce their clutch size. The alternative explanation, namely, that secondary females are intrinsically low-productive, for example, because of relatively younger age, can probably be refuted. Large males were found to be overrepresented among the bigamists. Male fitness is relatively variable under the mating system of the pied flycatcher; this encourages strong sex dimorphism. The situation is summarized in our contention that, in the "battle between the sexes," the male sex is relatively victorious in the pied flycatcher as compared with most altricial bird species which are strictly or almost strictly monogamous.