Implications. Prey naivete has long been considered as the root cause of the devastating impacts of alien predators, whereby native prey simply fail to recognise and respond to the novel predation risk. Our results reveal a more complex form of naivete whereby native prey appeared to recognise alien predators as a threat but their response is ultimately inadequate. Thus, recognition alone is unlikely to afford protection for native prey from alien-predator impacts. Thus, management strategies that, for example, train prey in recognition of novel threats must induce effective responses if they are expected to succeed.