Innovative training program helps goannas survive cane toad invasion

In a groundbreaking study from Macquarie University, scientists have developed a novel strategy to protect native wildlife from the lethal threat of cane toads. The team, led by Postdoctoral Research Fellow Dr Georgia Ward-Fear, has successfully trained goannas in the Kimberley to avoid eating the poisonous amphibians with promising results. Cane toads have been a persistent menace since their introduction to Australia in 1935 to control pest beetles in sugar cane fields. Their rapid spread has wreaked havoc on native species, particularly apex predators such as goannas, which has far-reaching consequences for ecological balance in northern Australia. “When apex predators like goannas eat an adult cane toad, they die quickly and painfully — and when they disappear, it affects the whole food web. This imbalance sends ripples through the whole ecosystem,” Dr Ward-Fear said. The research team used a technique known as “conditioned taste aversion” to immunise goannas against the threat of cane toads. By initially exposing the lizards to small, less toxic cane toads, they induced illness without causing death, teaching the goannas to associate the toads with a negative experience and thereby avoid eating them in the future. This method was put to the test in areas of the Kimberley facing the imminent arrival of cane toads. The results were striking, with taste-trained goannas showing significantly higher survival rates compared to those in control areas, where goanna populations declined by up to 94 per cent following the arrival of adult cane toads. In areas where the technique was implemented, goanna populations not only stabilised but in some cases exceeded pre-invasion numbers, ranging from 35 per cent to 140 per cent of their original size. While the intervention focused on relatively small and specific populations, its implications for wildlife conservation are significant. “By managing the initial impact of the invasion, we see ongoing survival of goanna populations because after cane toads invade and begin breeding, plenty of baby toads will ‘train’ the next generation of goannas, without us having to keep adding more toads to the system,” Dr Ward-Fear said. “While it’s impossible to deploy ‘teacher toads’ right across the Australian tropics, we can maintain pockets with healthy predator populations, and potentially these can repopulate areas where goannas have become locally extinct. “We’re optimistic that even a single deployment can have long-term effects.” It comes as the “cane toad frontline” hit Derby earlier this year, with the pests also spotted in Broome several times in the past year.