Sound discrimination and orientation in smooth newts (Lissotriton vulgaris)

Netws orientate using multiple cues and at least one species may rely on advertisement calls of sympatric species to locate breeding sites. However not all the species use the same kind of breeding sites, so it would be a better strategy for a newt to follow preferentially the call of the species that share the same microhabitat for breeding. In this study we tested if the smooth newts (Lissotra'ton vulgaris) were able to discriminate the playbacks of the advertisement calls of two sympatric toads (Bufo bufo and Pseuduepiahka viridis) that breed in ponds with different features. We collected adult newts of both sexes from the "Paludi di Arsago" Special Area of Conservation, Northern Italy. In a first experiment we tested 10 males and 10 females by presenting each one the playbacks of choruses of B. bufo and P. viridis jn two separated trials. in the second experiment we tested other 11 males and 9 females by presenting them the two playbacks simultaneously. The two experiments were conducted in a circular arena in total darkness; order and direction of presentation of the stimdi were randomized appropriately to avoid any undesired effecc The experiments were performed on 15 April 2006. All the directional responses were analyzed using standard circular statistics. In the first experiment neither order and direction of the stimuli had any significant effect on the orientation responses of the newts. Both sexes showed a significant phonotactic response, independently from the species presented, while in the second experiment newts preferenhlly orientated towards the playback of B. bufo. Our results demonstrated that smooth newts are capable of discrimination implying that they can effectively colIect infrmation on environmental sounds to orientate. Since B. bz&o in northern Italy is more associated with smooth newts than P. viridis, the preference for its playback Ih the second experiment suggest that newts can use heterospecific calls to select the best suitable breeding sites.