Polygyny in the pied flycatcher (Ficedula hypoleuca): comparison of deception and non-deception models

Abstract

Since the evolutionary significance of polygynous mating systems was first recognized, many models have been proposed to explain why females mate with already-mated males. In the pied flycatcher (Ficedula hypoleuca), a particulary well studied polygynous passerine species, two models of polygyny are most prominent nowadays: one in which already-mated males deceive the females about their mating status, and one in which the status of already-mated males is known to the females that decide to mate with them anyway, “making the best of a bad job”. In our study we compared the models by computer simulation and then compared the results with available field data. The results showed that the proportion of secondary females increased when the density of males increased, as well when the operational sex ratio increased in favour of females. However, these results were indistinguishable between the models when number of simulation repetitions was low. This may suggest that a secondary female frequencies collected in the field may not be a good test of which model (deception or nondeception) better explains polygyny in the pied flycatcher unless the data are collected for a sufficient number of breeding seasons (at least 20).