A native apex predator limits an invasive mesopredator and protects native prey: Tasmanian devils protecting bandicoots from cats

Apex predators can limit the abundance and behaviour of mesopredators, thereby reducing 29 predation on smaller species. We know less about whether native apex predators are effective in 30 suppressing invasive mesopredators, a major global driver of vertebrate extinctions. We use the 31 severe disease-induced decline of an apex predator, the Tasmanian devil, to test whether devils limit 32 abundance of invasive feral cats and in turn protect smaller native prey. Cat abundance was ∼58% 33 higher where devils had declined, which in turn negatively affected a smaller native prey species. 34 Devils had a stronger limiting effect on cats than on a native mesopredator, suggesting apex 35 predators may have stronger suppressive effects on evolutionarily naive species than coevolved 36 species. Our results highlight that apex predators not only regulate native species but can also 37 confer resistance to the impacts of invasive populations. Apex predators could therefore be a 38 powerful but underutilised tool to prevent biodiversity loss.