iHerp Australia Issue 11 | Page 8

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