Isolated populations of a given species may diverge from conspecifics for a certain series of traits. It is of particular interest when this divergence involves the signals and the related responses used by sexually reproducing animals to identify prospective mating partners. Using behavioural trials during reproductive season, we studied pheromone-mediated response between insular and mainland European whip snakes, Hierophis viridiflavus. Our results revealed that both insular and mainland males can utilise both homotypic and heterotypic chemical cues. However, while insular snakes did not show any preference between the two types of chemical cues, mainland males preferred homotypic odours. These results, though preliminarly, show the existence of asymmetry in the displayed behavioural patterns and support the idea that isolated populations may evolve differences in communication systems.