Crayfish predation on tadpoles:: A comparison between a native (Austropotamobius pallipes) and an alien species (Procambarus clarkii).

In the laboratory, the motivation and/or ability to prey on anuran larvae (Bufo bufo, Rana kl. esculenta and R. italica) were compared between a native European (Austropotamobius pallipes) and an alien North American crayfish species (Procambarus clarkii). Both were skilled predators of tadpoles, adopting a sit-and-wait strategy. However, because P. clarkii displayed lower latency times in the presence of one of the three amphibians (Rana kl. esculenta) here tested, the hypothesis is raised that invasive crayfish are more opportunistic predators and possibly faster in switching to different prey than those species they are displacing. From a conservation perspective, these preliminary results further emphasise the importance of studies centred on the invasion-displacement dichotomy.