Agriculture minister says size of colony in Mandalong indicates there could be many more of the toxic intruders in the area
New South Wales is on alert after more than a dozen cane toads were found on a private property an hour’s drive north of Sydney.
The state’s Department of Primary Industries (DPI) biosecurity helpline confirmed a report had been made by a member of the public on 19 September after a “number” of cane toads were found at a property in the rural town of Mandalong, west of Lake Macquarie.
An initial 17 were caught by a joint NSW government and University of Newcastle team the following day.
A further two have been found since, while investigations into how the cane toads arrived in the area were ongoing.
It’s not uncommon for a cane toad or two to arrive in surprising spots via truck. But the minister for agriculture, Dugald Saunders, said the size of the colony indicated “there could be many more in the area”.
He said it was “critical” for community members to be diligent keeping an eye out for and reporting “rogue toads”.
“Now is not the time for complacency – cane toads pose a significant risk to our domestic and native fauna and it is critical we keep them out of NSW,” he said.
Sign up to receive an email with the top stories from Guardian Australia every morning
Rick Shine, a professor at the School of Natural Sciences at Macquarie University, said toads were “adept” at catching a ride on the back of trucks and on a person’s shoe.
“They turn up all over the place, in someone’s boot when they get off the airport … in Canberra and Dubbo and even on top of Mount Kosciuszko,” he said.
“It’s not unusual for one or two to turn up in places a long way from home – but it’s unusual to get this number.”
Shine said in recent years a similar sizeable population outbreak in Sydney’s suburbs near the airport managed to be quashed with a quick community response.
“Many hundreds were caught,” he said. “They found the places they were breeding and prevented the breeding from occurring. There hasn’t been a toad seen in years, so it can be stopped.”
The danger, though, was the capacity for breeding.
“We simply don’t know, there could be hundreds, there could be thousands, they take a year or two to mature,” Shine said.
Sign up to Guardian Australia's Morning Mail
Our Australian morning briefing email breaks down the key national and international stories of the day and why they matter
“Nobodies going to get terribly excited about one or two, they’ll likely die a lonely death but with 20,000 eggs you get a lot of toads very quickly, and that’s bad news for the local predators.
“It’s not out of question [for an outbreak] but it needs to be a good, warm summer. We’re moving into the danger period now … given the sizes of toads collected, I would presume there was a breeding event last summer – they come in a range of sizes.
“Once they lay their eggs, in the warmer time of the year eggs hatch within a day, tadpoles in a month, and they emerge as tiny toadlets.”
If there is an outbreak, the impact on local wildlife is likely to be catastrophic. Cane toads are toxic at all life stages, placing a threat on native animals and pets that may attack them.
“Toads have a very distinctive poison, it’s different from chemical defences used by native frogs,” Shine said. “Some of the predators that eat frogs are not able to deal with the toxin and die of heart attack very rapidly.
“There’s going to be a lot of dead black snakes very quickly, dead goannas, some of the other lizards, quolls – we certainly would see an impact on biodiversity [if there’s an outbreak], their eggs are very toxic and can kill turtles and fish.
“Having cane toads as your new neighbours is not good news.”