Acoustic orientation in the great crested newt (Triturus cristatus)

Abstract

We carried out laboratory experiments to determine whether orientation during migration in the great crested newt (Triturus cristatus) is influenced by acoustic information. Newts retrieved during the aquatic breeding seasons (adults), as well as during the terrestrial phase after breeding (adults and juveniles), were subjected to calls from sympatric (Rana temporariaandBufo bufo) and allopatric (Lithobates catesbeianus) anurans. In addition to natural stimuli, we also used modified anuran calls (continuous sound with inter-note intervals removed), white noise with and without envelop, and a heterochthonous sound (pile driving). In a circular arena, adult newts retrieved both during their aquatic and terrestrial phase orientated towards theB. bufostimulus, and migrated at random directions when exposed to the other calls; the lack of orientation towards the sympatricR. temporariaparallels a largely non-overlapping breeding season. Inexperienced juveniles did not orientate towards anuran calls, suggesting that phonotactic responses could be learned. Both aquatic as well as terrestrial adults significantly moved away from a white noise envelop. The results suggest different degrees of heterospecific call attraction across life stages, and provide evidence that unnatural sound might have an adverse effect on breeding migrations.