New method: Studies have shown that toxic cane toads are making a significant dent in some Australian crocodile populations.
Credit: University of Sydney
SYDNEY: Australian scientists are serving up mashed cane toad with a dash of poison to put predators off eating the toxic aliens.
The cane toads, which carry poisonous sacs on their heads that can kill animals as big as crocodiles within minutes, are spreading rapidly westwards across the country despite efforts to eradicate them (see, Cane toads killing Australian crocs).
"Native predators are actually pretty capable of learning to avoid cane toads if given the chance," University of Sydney professor, and the leading authority on the cane toad invasion, Rick Shine told the Australian Broadcasting Corporation this week.
Marauding amphibian
"We're learning about ways to educate the predators in advance of the toad front in ways that will help them survive once the toad arrives in their territory."
Originally from Central and South America, the marauding amphibian (Bufo marinus) was introduced to Australia in 1935 in an attempt to control beetles ravaging sugar cane fields in the tropical northeast.
But – like many animals imported into Australia – the cane toad has turned into a pest, with recent research showing they have more than halved the number of crocodiles in some Northern Territory rivers.
Attempts to minimise the damage focused on trying to kill the toads, but "it's hard to do and it's clear that the toad is by and large winning the battle," Shine said.
"The invasion-front toads are all very big guys, so they've got a lot of poison, so the first toad you meet if you're a goanna [lizard] is almost bound to a big one, and it's almost bound to be your last meal."
However, if predators ate a small toad that made them sick but was not big enough to kill them, they rapidly learned to avoid the warty hoppers, he said (see, Who's afraid of the big bad toad?).
Reducing the carnage
So the scientists are working on a new program of feeding animals such as crocodiles and goannas a mixture of toad bits and a poison to make them "desperately nauseous."
"(This will) convince predators that anything that looks and smells and tastes at all like a toad is a good thing to avoid," Shine said.
Initial results showed that predators, including quolls [carnivorous marsupials] quickly learned that the aliens were not a good addition to their diet. "(It) suggests there is at least some hope that we can reduce the carnage that toads cause to these big predators," he said.
