Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
80 years after their introduction, could cane toads finally be on the decline in Queensland?
Anecdotes from around the state suggests the invasive pests are less pervasive than they used to be, while residents in the Northern Territory and northern parts of Western Australia report increasing hordes of the Rhinella marina.
Professor of Evolutionary Biology at the University of Sydney and one of Australia's leading cane toad experts Rick Shine said the signs were hopeful.
"We don't really have good data to tell us just how much their numbers have dropped," he said.
"But it is clear that in many of these areas where they were once very common, the numbers are much lower than they once were."
Dr Shine said the problem was that human memory was fallible.
"When we first see these giant toads, we are shocked at how big they are and how many of them there are, but then we get used to them and they don't look quite so big and we don't get excited about how many of them there are," he said.
"It doesn't matter if the toads arrived in 1950 or 1970 or 1990 people all tell the same story – that there aren't as many as there used to be."
It's generally accepted wisdom that the arrival of cane toads in 1935 heralded one of the greatest environmental disasters in Australian history.
But Dr Shine said the reality was that Mother Nature was a "complicated lady" and the introduction of the pest had created winners and losers.
"When the cane toads first arrived they caused 90 per cent mortality in the big goannas, and that's really bad news," he said.
"On the other hand, if you're one of the smaller animals that used to be eaten by goannas, this is the best news you've ever had.
"If you're a frog, a cane toad is a booby-trapped super hero, going around killing around everyone who likes to kill frogs."
He said while some species, particularly goannas and snakes, had experienced big population drops, cane toads had not caused any species to become extinct.
"The good news if you go to areas where the toads have been present for many decades, then a lot of those predators have come back again," he said.
"It seems that the impact of toads is relatively transient – it's very bad news, but the ecosystem does deal with it, and those predator species somehow work out to co-exist with toads."
Dr Shine said many had learned to utilise toads for food, with birds and insects easily able to pick off the smaller ones.
But he said while it showed the country's ecosystem was far more robust than some people gave it credit for, it was no reason for an excuse.
"It's perhaps an encouraging story about the resilience of some of these complex tropical communities," he said.
"The difficulty is cane toads are just one challenge, and you throw in climate change and pollution and a whole bunch of other things and you start to get towards the last nail in the coffin."
