Immediately after cane toad invasion of Kakadu, quolls became extinct at one study site and declined from 45 individuals to five at another site. The northern quoll may cease to exist in most areas in the Top End once the cane toad population completely overlaps the northern quoll's range. However, remnant populations of northern quolls still persist in Queensland where cane toads have been present for decades. These persisting Queensland quoll populations are naturally toad averse (as observed on remote cameras). One of the northern quoll populations studied in Kakadu during the recent cane toad invasion, had a few individuals survive the invasion. These individuals were, likely similar to the Queensland quolls, genetically averse to the toads. In 2003, to help protect northern quolls, numerous quolls were transferred to the toad-free English Company Islands (Astell and Pobassoo Islands), off the coast of Arnhem Land. Quolls thrived on these islands, with an estimated population of 2193 female northern quolls on Astell Island by 2014. In 2017, quolls from Astell Island were collected, trained via conditioned taste aversion to avoid attacking cane toads and reintroduced to Kakadu National Park. This reintroduction attempt saw the release both toad-trained (22) and toad-naive (9) northern quolls to an area of Kakadu that previous had quolls but where they had recently gone locally extinct due to the invasion of cane toads. Although the toad-trained quolls survived longer than those that received no toad training, ultimately this reintroduction population rapidly went extinct because of dingo predation. Subsequently, research comparing antipredator behaviours of quolls from Astell Island and mainland Queensland determined that quolls conserved on this island had lost their ability to recognise and avoid both dingo and cats, predators they have co-evolved with on mainland Australia for at least 3500 and 150 years respectively. This study suggests that animals conserved in complete isolation from predators can rapidly lose evolved antipredator behaviours, in this case in only 13 generations, when they are no longer maintained via natural selection.