What happens when you let a predator loose in a fenced conservation area?

In the first reintroduction of western quolls to a fenced conservation reserve, researchers from UNSW and Arid Recovery watched closely to measure their impacts on local prey species.

While quoll predation and drought impacts caused declines in prey species, quolls did not hunt any species to local extinction.

In Australia, many endangered wildlife have been reintroduced into fenced reserves, where they are safe from non-native predators – such as foxes and cats – that led to their initial decline across the country. However, historically these reserves have been free from native mammalian predators too.

In recent years, these fenced reserves, also known as ‘safe havens’, have begun reintroducing native predators as a ‘stepping stone’ for helping endangered species survive back in the wild. The reintroduction of predators helps to regulate overabundant prey numbers and address the issue of prey ‘naivety’ (a loss of predator awareness), which often results from living within these safe havens.

Benjamin Stepkovitch, a PhD student from the UNSW Centre for Ecosystem Science, analysed the impact of reintroducing western quolls to the Arid Recovery Reserve over four years. The results were recently published in Animal Conservation.

“Reintroducing native predators has been proposed to not only conserve the predators themselves, but to help restore ecosystem balance inside fenced reserves,” says Mr Stepkovitch.

“Our study found that quolls had a dietary preference for some reintroduced prey species and native rodents, which in conjunction with a drought, contributed to the decline of some of these species in the reserve. However, quolls also switched to more abundant prey species when others declined. For bilbies, bettong and bandicoots, this meant that their populations persisted and bounced back after the drought. For stick-nest rats, the story was more complex.”

With more conservation reserves planning to reintroduce western quolls in future, the research team are suggesting that careful selection of species and ongoing management is required to help balance predator and prey reintroductions into fenced reserves across Australia.