Calling by male midwife toads stimulates females to maintain reproductive condition

Abstract We investigated the effect of the calls of male Mallorcan midwife toads, Alytes muletensis , on the reproductive condition of females. We used three groups of gravid laboratory-reared females. One group was kept in silence, one group was played heterospecific male calls and one group was played conspecific male calls. Only the females that heard conspecific male calls continued to ripen and mature their eggs while females in the other two groups reabsorbed resources from their eggs. We conclude that conspecific male calls have a stimulatory effect on the reproductive physiology of females, such that gravid females hearing the calls maintain their reproductive condition. The calls of male frogs have previously been shown to act only in male–male competition and to attract females. This is the first experiment to show that the call of a male frog affects the reproductive status of females.