Global determinants of prey naiveté to exotic predators

Prey naiveté—the failure of prey to recognize novel predators as threats—is thought to exacerbate the impact that exotic predators exert on prey populations. Prey naiveté varies under the influence of eco-evolutionary mediating factors, such as biogeographic isolation and prey adaptation, although an overall quantification of their influence is lacking. We conducted a global meta-analysis to test the effects of several hypothesized mediating factors on the expression of prey naiveté. Prey were overall naive towards exotic predators in marine and freshwater systems but not in terrestrial systems. Prey naiveté was most pronounced towards exotic predators that did not have native congeneric relatives in the recipient community. Time since introduction was relevant, as prey naiveté declined with the number of generations since introduction; on average, around 200 generations may be required to erode naiveté sufficiently for prey to display antipredator behaviour towards exotic predators. Given that exotic predators are a major cause of extinction, the global predictors and trends of prey naiveté presented here can inform efforts to meet conservation targets.

Australian native mammals recognize and respond to alien predators: a meta-analysis

Prey naiveté is a failure to recognize novel predators and thought to cause exaggerated impacts of alien predators on native wildlife. Yet there is equivocal evidence in the literature for native prey naiveté towards aliens. To address this, we conducted a meta-analysis of Australian mammal responses to native and alien predators. Australia has the world's worst record of extinction and declines of native mammals, largely owing to two alien predators introduced more than 150 years ago: the feral cat, Felis catus , and European red fox, Vulpes vulpes . Analysis of 94 responses to predator cues shows that Australian mammals consistently recognize alien foxes as a predation threat, possibly because of thousands of years of experience with another canid predator, the dingo, Canis lupus dingo . We also found recognition responses towards cats; however, in four of the seven studies available, these responses were of risk-taking behaviour rather than antipredator behaviour. Our results suggest that a simple failure to recognize alien predators is not behind the ongoing exaggerated impacts of alien predators in Australia. Instead, our results highlight an urgent need to better understand the appropriateness of antipredator responses in prey towards alien predators in order to understand native prey vulnerability.