Reintroduction of Tasmanian devils to mainland Australia can restore top-down control in ecosystems where dingoes have been extirpated

•We modelled the reintroduction of the Tasmanian devil to mainland Australia.•Devils appear to replace some of the lost function associated with dingo removal.•In scenarios with devils, ecosystem assemblages were more equitable.•Importantly, devils appear to suppress foxes and cats and regulate grazing species.•A mainland devil population could insure against devil extinction in Tasmania.

Restoring missing ecological interactions by reintroducing locally extinct species or ecological surrogates for extinct species has been mooted as an approach to restore ecosystems. Australia's apex predator, the dingo, is subject to culling in order to prevent attacks on livestock. Dingo culling has been linked to ecological cascades evidenced by irruptions of herbivores and introduced mesopredators and declines of small and medium sized mammals. Maintenance of dingo populations is untenable for land-managers in many parts of Australia owing to their depredations on livestock. However, it may be possible to fill the apex predator niche with the Tasmanian devil which has less impact on livestock. Devils once occurred throughout Australia, but became extinct from the mainland about 3000 years ago, but are now threatened by a disease epidemic in Tasmania. To explore the feasibility of reintroducing devils to mainland Australia we used species distribution models (SDMs) to determine if suitable climatic conditions for devils exist and fuzzy cognitive mapping (FCM) to predict the effects of devil reintroduction. Based on devils' current distribution, our SDM indicates that suitable areas for devils exist in south-eastern Australia. Our FCM examined ecosystem responses to predator-management scenarios by manipulating the abundances of devils, dingoes and foxes. Our FCMs showed devils would have cascading effects similar to, but weaker than those of dingoes. Devil introduction was linked to lower abundances of introduced mesopredators and herbivores. Abundances of small and medium sized mammals and understorey vegetation complexity increased with devil introduction. However, threatened species vulnerable to fox predation benefited little from devil introduction. Our study suggests that reintroducing ecological surrogates for apex predators may yield benefits for biodiversity conservation.

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