The price of perfume: chemical communication and predation risk in an anuran

Abstract Chemical signals play a key role in intraspecific communication in many animal species, especially in reproductive contexts. However, these signals may entail costs if detected by predators. In anurans, studies on communication have traditionally focused on acoustic signals, while the use and function of chemical cues remain poorly explored, making it unknown whether these secretions are involved in conspecific recognition or might increase predation risk. This study explores this dual role in the natterjack toad, Epidalea calamita (Laurenti, 1768), assessing whether secretions are involved in sex recognition and whether their emission carries a predation cost. To do this, we conducted two complementary experiments: the first assessed the behavioral responses of males and females to conspecific secretions and a control, and the second measured predator attacks on plasticine models impregnated with male or female secretions. Results showed that females spent significantly more time in areas with male secretions, suggesting attraction to these cues, while males showed no clear preference. At the same time, plasticine models treated with male secretions received significantly more predator attacks than those with female secretions. These findings suggest that male chemical signals in E. calamita may function as attractive sexual cues for females, but also increase detectability by predators, pointing to a potential evolutionary trade-off between sexual attraction and predation risk mediated by chemical communication in this species.