How do predators learn not to eat toads? Native
animals aren’t stupid. If the first Cane Toad they meet
is a small one, they eat it, they feel nauseous, and they
stop eating toads in future. The process is called
‘Conditioned Taste Aversion’, and it’s very widespread.
It even occurs in our own species. I can testify to its
power on a personal level, based on a camping trip
when I was a teenager 50 years ago. The trip involved
me drinking a bottle of Scotch Whisky, and being
violently ill afterwards. And half a century later, the
smell of Scotch Whisky still makes me want to throw
up. Judging by the look in the eyes of quolls and
goannas when they learn the perils of ‘toad tasting’, I
reckon they feel the same way that I do when
somebody opens a bottle of Scotch.
first toad you meet is a large one, you die. That’s a
problem because, as I mentioned above, all of the
Cane Toads at the invasion front are large - the small
ones can’t keep up with that rapid (60km per annum)
“Some southern boffin wants to
release MORE bloody Cane
Toads!!??”
range expansion. So all across Australia, thousands of
large predators die as soon as the wave of croaking
death turns up on their doorstep. Goannas are good at
finding frogs, and a Cane Toad is easier to find than a
Above: the arrival of Cane Toads is a catastrophe for many
native frog. The first evidence of toad invasion is often
goannas, like this Mitchell’s Water Monitor. Unable to tolerate the discovery of dead goannas, because these giant
the toad’s poison, any goanna that attacks a large Cane Toad is lizards find the newly-arrived toads well before people
likely to drop dead of a heart attack. Image by Michelle
do.
Franklin.
Right: Some Australian snakes, like this Keelback, are very But we can change that outcome. We can give the
resistant to the Cane Toad’s poison, and enjoy a spicy snack
predators a chance to learn BEFORE the main toad
whenever the opportunity arises. Image by Greg Brown.
invasion arrives. How? It’s simple, but bold. We can
The equation is straightforward. If the first toad you
meet is a small one, you learn not to eat toads. If the