Lack of polygyny in Central European populations of Reed Warblers Acrocephalus scirpaceus

So far discussions on the occurrence of polygyny have been conducted on an inter-specific or individual level. In this paper we analyse differences in polygyny rate between different populations of Eurasian Reed Warblers. We provide evidence that our study population in SW Poland, and also the nearby Slovak population, are purely monogamous in contrast to those from western Europe, and we discuss hypotheses regarding the occurrence of polygyny. We suggest that birds breeding in different parts of Europe may exhibit different strategies for optimising reproductive success. In richer habitats of western Europe, where solitary females are able to successfully rear their young, polygyny is more frequent and extra-pair copulations relatively rare. In contrast, in central Europe, where costs of rearing young unaided are high, males do not try to attract second females but engage more often in extra-pair copulations.