Phonotaxis by Female Majorcan Midwife Toads, Alytes Muletensis

Abstract

Female choice based on male call characteristics has been experimentally demonstrated in a number of species of anurans. In the Majorcan midwife toad, the male performs parental care by carrying the eggs in a string around his hind legs until they are ready to hatch. Both sexes produce calls to advertise sexual receptivity and both show phonotaxis towards the calls of the opposite sex. We used two-choice phonotaxis experiments to investigate whether females assess male caretaking ability using variation in call characteristics. Both call frequency and call duration are good indicators of male size, a characteristic that potentially influences the ability of males to successfully brood a clutch. Variation in call repetition rate and call intensity may also reflect differences in male caretaking ability, given the high energetic demands of calling behaviour in anurans. We predicted that females should prefer to mate with larger males and that this would be manifest in selective phonotaxis to low frequency and/or long duration calls. We also predicted that they would prefer calls produced at a fast rate and a high intensity. Contrary to our predictions females did not prefer lower frequency calls, longer calls or louder calls. They did however, selectively approach calls produced at a faster rate. These results are discussed in the context of sexual selection theory.