Sex recognition and mate choice in male Rana kukunoris

Mate recognition is important for successful reproduction, and consequently species have evolved various ways to recognize potential mates. Little is known about mate recognition in male Rana kukunoris, a temperate frog endemic to China. In the present study, we investigated experimentally whether male R. kukunoris can discriminate between conspecifics of different sexes, between gravid and non-gravid females of similar size, and between gravid females of different sizes. When offered the choice between a gravid female and a similar-sized male, the focal male attempted to clasp both sexes with equal frequency. Test males only released the stimulus frog when a release call was emitted by the stimulus male. Test males did not differentiate between gravid and non-gravid females of equal size either. However, male frogs preferred large females over smaller females. The results suggest that male R. kukunoris discriminate between the sexes based on the release calls of males, and between females of different sizes using visual cues.