Where are the rats? Small mammal responses to a predator-free safe-haven in the Barrington Tops

In the past 200 years, mammal declines in Australia have far exceeded those observed anywhere else in the world. The catalysts for these declines are primarily introduced predators and land-use changes. Mammals have declined most in the arid zones of Australia and least in areas of higher rainfall. One contemporary solution for conserving Australia’s threatened species is to create predator-free islands or fenced areas which act as safe-havens for both threatened reintroduced species and existing species already present in the environment. Here, we investigated the effects that a safe-haven has on small mammals (<200 g) in tall forest at Barrington Tops at an elevation of 1300 m. We assessed small mammal assemblages and ground cover vegetation inside and outside the safe-haven in comparable habitats. The abundances of Antechinus stuartii and particularly Rattus lutreolus were greater inside the safe-haven; surprisingly, Rattus lutreolus was rarely captured outside of the safe-haven. Vegetation cover below waist-height (100–120 cm) was much denser inside the fenced area than outside. Our findings are significant because they showed that two native small mammal populations at Barrington Tops have benefited from the exclusion of introduced predators and large herbivores even though their conservation status is least concern. Our findings have implications for efforts to conserve native mammals because they provide insights into the extent to which small mammals, particularly native rodents, may have declined in the forests of south-eastern Australia and highlight that our understanding of the threats posed to their conservation status is under-appreciated.