A novel female call incites male–female interaction and male–male competition in the Emei music frog, Babina daunchina

In anurans, females generally remain silent during mating or only produce calls of very low intensity before mating. Consequently the functions of female calls are not as well understood as those produced by males. We investigated a novel female call produced during mating in the Emei music frog. The functions of the female call during reproductive behaviours were evaluated by field and seminatural playback experiments. During mating, low-intensity female calls (approximately 3.2 s in duration) alternated with male sexual movements (approximately 1.34 s in duration). Female calling was sometimes prolonged when we interrupted male movements, which is consistent with the idea that female calls may stimulate male sexual activity and perhaps facilitate ovulation. In their natural environment, Babina males vocalize and mate in well-hidden underground nests. Field playback experiments showed that female calls significantly increased the rate of male advertisement calling which may help females locate males. Males also showed significant positive phonotactic responses to playback of female calls, and increased aggressive call production and other aggressive behaviours which females may use as cues for mate selection.