The best of both worlds: Why antipredator traits are lost in predator-free havens and how to keep them

As a response to the current biodiversity crisis, active management of threatened species has become more frequent, with predator-free havens an increasingly common conservation management strategy. In Australia, where introduced predators such as cats and foxes are one of the largest threats to native fauna, havens have played a key role in maintaining viable populations of endemic marsupials. Concerns, however, have been increasingly raised that populations in predator-free havens, or similarly those that are captive bred or on predator-free islands, rapidly lose antipredator traits. Here we suggest that some of the selective pressures and mechanisms that may explain the rapid loss of these traits may have been overlooked. There is convincing evidence within the animal production literature that a fearful, high anxiety temperament (typically associated with anti-predator behaviours) is genetically associated with reduced fecundity; a relationship that may explain the rapid loss of fearful antipredator traits as a byproduct of strong selection for fecundity in havens. We also propose mechanisms by which antipredator behaviour could be maintained in populations that are expected to evolve predator naivety. There is the potential for haven and captive bred populations to be managed to ensure the best of both worlds: anxious, predator-wary individuals selectively maintained for release into the wild, and low anxiety, high fecundity individuals removed for island refuges and public-facing conservation education. • Populations in predator-free havens often lose predator anxiety • In vertebrates there are common neuroendocrine drivers of fecundity and anxiety • Havens release animals from the trade-offs between predator anxiety and fecundity • Fecundity selection may drive down predator awareness in havened populations • Active management may counter fecundity selection, maintaining antipredator behaviour