Vocal Behavior of Males and Females in the Majorcan Midwife Toad

Abstract

Vocal behavior and advertisement call structure of the Majorcan midwife toad (Alytes mu- letensis) are described. Both sexes possess courtship vocalizations. Females called in response to calls of males, in the initiation of courtship, and while physically competing over access to mates. Females advertised for mates only when heavily gravid and in danger of losing their eggs. Advertisement calls of females were shorter, repeated at a faster rate, and produced at a lower sound pressure level than the calls of males. The sound pressure levels of both male and female calls were low relative to other anurans. Male body size was positively correlated with call duration and sound pressure level, and negatively correlated with dominant frequency. Female body size was not significantly related to any call parameters. The evolution of female advertisement calls is discussed with reference to other anuran species in which females are known to produce courtship vocalizations. A hypothetical evolutionary pathway is proposed in which a dispersed breeding habitat and a female-biased OSR facilitate the evolution of female advertisement calls.