Bandicoots flourish in the presence of Tasmanian Devils, apparently because the Devils suppress feral cats that otherwise prey on the native mammals, according to a recent study by Calum Cunningham of the University of Tasmania.
The research found 58% fewer cats in areas with healthy devil populations compared to places where devils had declined; and that southern brown bandicoots were only ever abundant when cats were rare.
The mechanism behind the relationship isn’t entirely clear. Tasmanian Devils may prey on feral kittens and out compete cats for prey, and cats may avoid areas where Devils are plentiful. Invasive cats have had a huge impact on native mammals (like bandicoots), birds and reptiles in Australia, yet Devils aren’t typically big predators of bandicoots.
Rabbits are also preyed upon by feral cats and help maintain predator populations.