Cane toads are creeping closer to Sydney after a “concerning” population found at Lake Macquarie

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It’s not unusual for the quirky cane toad to hop on a truck or car and hitchhike down New South Wales’ east coast, but a growing population of these warty, poisonous pests have found their way onto a private property an hour’s drive north. of Sydney – and the threat is being taken seriously by biosecurity experts.

The cane toads were found hidden under a tin plate on a private property at Mandalong, a suburb of southern Lake Macquarie in the Hunter region.

The NSW Department of Primary Industries (DPI) biosecurity team admits it is possible the invasive pest has bred on the property.

If this proves true, it says the potential for “explosive” numbers to appear in the summer months is an unwelcome but real prospect.

“We’re still getting a handle on how big a problem this is and we won’t know until we have a few weeks of community reporting to see how far this population can go,” NSW DPI biosecurity manager Quentin Hart said.

The toxin-oozing cane toad is widely recognized as a destructive predator that can destroy native animals and ecosystems. They can also poison livestock if swallowed.

A total of 17 cane toads were initially found on the property.

NSW DPI has confirmed the discovery of a further two toads in a subsequent search.

Top view of 17 deceased cane toads arranged in order of size
The first 17 cane toads found on the Mandalong property.(Provided: John Clulowv)

First outbreak since 2010

Mandalong is more than 500 kilometers south of an established cane toad containment zone around the Clarence Valley on the NSW north coast.

It is believed to be the first significant outbreak of cane toads beyond that buffer zone since 2010, when the amphibians took up residence at Sydney’s Taren Point.

The big question is: Did the toads breed on site or were they unknowingly brought in as little toads, for example in garden items or other items brought onto the property?

“We may be lucky, it may be confined to this very local area,” Mr Hart said.

“But we won’t really know the true situation until we can assess whether cane toads are breeding this summer.”

If the toads bred locally from tadpoles, it seems they will be much more difficult to eradicate.

Zoomed in map of Australia highlighting NSW as being sugar cane free.  A marker near Newcastle indicates Mandalong
The cane toads were found at Mandalong, 120km north of Sydney – an area considered toad-free by the NSW DPI.(Supplied: NSW DPI)

Cane toads in Australia

The cane toad is an introduced pest that was brought to Australia in the 1930s as part of a biological control program for beetle pests affecting the sugar cane industry.

They are really prolific breeders, more so than rabbits, according to conservationist John Clulow, a former associate professor at the University of Newcastle.

“A female of decent breeding size can produce 25,000 to 35,000 eggs in a single season,” he said.

“Most of them in a good breeding event would be fertilized and become tadpoles in a pond. So you don’t need too many.

“If one or two females succeed, then you have a real problem.”

Cane toad at Mandalong, NSW
Local Land Services employee Laurie Mullen, with one of the 17 toads found at Mandalong.(Supplied: NSWDPI)

Professor Clulow has been assisting the NSW DPI response since the toads were discovered last week, including testing tadpoles in a nearby waterway.

So far, only native frogs have been identified.

However, one of the toads in the Mandalong cluster was a fully developed male of reproductive age.

“The worrying possibility is that they may have been the result of a breeding event down there at Mandalong,” Professor Clulow said.

“That’s the real concern here, and I think that’s what concerns DPI and biosecurity people, is that we could have a big problem on our hands.”

According to Professor Clulow, numbers can be “explosive”, especially when cane toads move into new areas.

“When a population moves into a new area, it can be really catastrophic for the native fauna,” he said.

NSW DPI is urging all residents in the area to look out for cane toads and report any sightings to the DPI Biosecurity Helpline on 1800 680 244.

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