Climate to blame for a new ‘cane toad front’

UTS, William Owens

(Image/Supplied)

Climate change is making NSW the perfect breeding ground for the stocky, warty cane toad.

Queensland’s cane toads are on the march – or make that “hop” – towards Sydney, if recent sightings and expert predictions are any indication.

Already this year, toads have been spotted on the Central Coast and in the heart of Parramatta – prompting speculation that they’re adapting to the increasingly warmer climate south of the border.

Evolutionary biologist and cane toad expert Professor Rick Shine is “utterly unsurprised” by the recent sightings.

He believes it is possible that cane toads could soon frequent the Sydney area.

“The model suggests that Sydney is almost too cold, but [cane] toads are adapting…” he said.

 

“We are having such extraordinarily hot summers with climate change, that they are actually doing fine.”

 

One monster amphibian, dubbed “Toad-Runner”, made nation-wide news after being spotted sitting by a dam near Somersby.

It was captured by a local family and handed in to the Australian Reptile Park.

Two other cane toads were discovered in the Parramatta area. One was found by a council worker, in the Stevens Street Reserve.

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Professor Shine says the main front in NSW is only moving a few kilometres a year: “But they are very good at hitch-hiking on trucks”.

“There was a population at Taren Point near [Sydney] Airport where they bred for at least three years. There were thousands and thousands of [cane] toads produced.”

Introduced into North Queensland in 1935, the cane toad was seen as a biological control for the cane beetle pest, which ate and destroyed sugar cane.

Not only did its arrival have little effect, but cane toad numbers soon exploded. Now, the “invasion front’ is continuing to expand into NSW and even Western Australia.

Although not wanting to downplay their impact, Professor Shine believes that the cane toads’ arrival will not devastate Sydney’s wildlife.

He says when they first arrive in an area, predators are often killed in vast numbers because they eat the highly toxic toads. Animals soon learn not to eat them, so their numbers recover.

“If you go to places where [cane] toads have been present for a long time, those species have come back again,” Professor Shine said.

In the meantime, Sophie Clarke from the Field of Mars Environmental Education Centre, is urging Sydney residents to be vigilant.

“Grab it if [you] can,” she advises. “Unless you squeeze it, the poison is not going to come out.”

 

“Put it in a box and call the Department of Environment and Heritage or the National Park, so someone can get it out.”

 

It is believed that the main cane toad front will spread across tropical Australia before any major solutions can be put into place, but efforts are being made to reduce their numbers.

Professor Shine believes that if they are ever to be successfully controlled, researchers must first develop a “tool kit” of various methods and strategies.

“I think taste aversion is the way to go, in order to buffer the impact upon predators.

“The key to controlling the actual numbers [however] is just to stop them breeding. We have developed methods for trapping tadpoles that can be very effective.”

When it comes to eradicating these warty creatures however, Professor Shine is wary.

 

“The reality is that biodiversity is in free fall and we are losing species all over the place.”

 

They are an invasive species, “but we are moving towards a world where there are all kinds of species in places that they don’t belong.

“If there is a species of toad that can live in the city when all [of] the others get killed, maybe we are better off having that one.

“We may be facing a world for our grandchildren where [we’d] be pretty happy to have a cane toad”.

– William Owens

 

This story is part of Covering Climate Now, a global collaboration of more than 220 news outlets to strengthen coverage of the climate story.