Discrimination of toad calls by smooth newts: support for the heterospecific attraction hypothesis

The ‘heterospecific attraction hypothesis’ (HAH) has been proposed to describe interactions between migrant and resident birds where migrants may indirectly select habitats using the presence/absence of residents. This hypothesis might be extended to other taxa, such as amphibians, which migrate yearly to breeding sites, sharing them with other species. However, the ability of amphibians to be cue-users is not quite obvious as for birds, and must be assessed first. Therefore, in this study we investigated how smooth newts, Lissotriton vulgaris, oriented facing two known species (the common toad, Bufo bufo, and the green toad, Pseudoepidalea viridis) and whether they oriented preferentially towards the calls of species that indicate the more suitable pond for breeding (B. bufo). Newts showed positive phonotactic responses for both species but clearly oriented towards B. bufo when the playbacks of the two toads were presented simultaneously. Our results support the idea that the ‘HAH’ might be extended to other taxa than birds.