Endangered marsupials taught to shun toxic toads

Australian scientists said Wednesday they had successfully taught an endangered marsupial to avoid eating toxic cane toads - a move they believe could help other at-risk species survive.

Sydney University ecologists said they had trained the northern quoll - a cat-sized marsupial - to suppress its instincts and refuse to eat the invasive amphibians, which are spreading across the country.

Big toads can be fatal to quolls if eaten whole. But the Sydney researchers were able to condition the marsupials to avoid eating them in the wild by feeding them very small toads tainted with a nauseating chemical.

Australia is beset by millions of cane toads, which carry a sac of venom on their heads toxic enough to kill snakes and crocodiles, and were introduced in the 1930s to control scarab beetles.

"It dawned on me that if we could teach northern quolls to associate sickness with cane toads, we might have a way of conserving them," researcher Jonathan Webb said.

The results, published in the British Ecological Society's Journal of Applied Ecology, showed that young quolls given the taste aversion treatment were more likely to associate the cane toad with feeling sick and avoid them.

The animals were tagged before being released into the wild and the researchers found that conditioned quolls survived up to five times longer than "toad-naive" quolls.

"Our results show that this kind of approach works," Webb said.

"If you can teach a predator that cane toads make you sick, then that predator will leave them alone afterwards. As a result, animals like quolls can survive in the wild even in a toad-infested landscape."

The quoll is facing extinction in many parts of the country as the cane toad spreads into some of its last remaining habitats.

The researchers said the next challenge was to scale up their work to make a difference to wild populations of other endangered species that see the deadly toads as food, such as goannas and bluetongue lizards.

"First, we have to check that the aversion we create to cane toads is long-lasting," researcher Professor Rick Shine said.

"If it is, the next step is to refine our delivery methods - for example, perhaps wildlife agencies could aerially deploy 'toad baits' ahead of the cane toad invasion front to educate quolls to avoid attacking cane toads."