A viral photo being circulated on social media showing reams of stringy gelatinous eggs comes with a warning to “pull them out”.
The post highlights growing concern that cane toads could take advantage of heavy rains, which have flooded large parts of NSW, and expand their territory.
Their eggs, which are laid in static bodies of water, could be carried into new areas by flowing creeks and rivers.
Cane toads, an introduced species, have wreaked havoc across Queensland, and they already have a foothold in northern NSW, with a biosecurity zone set up to slow their march south.
The species is particularly deadly for native wildlife, as they have glands which secrete a milky, white poison which when consumed often proves fatal.
Their spawn differs in appearance to that of native frogs, who lay in clusters of individual round eggs, instead appearing in long, noodle-like strings.
The eggs are capable of withstanding extreme temperatures, salinity and pH levels, and only last a couple of days before the tadpoles hatch.
Despite their strength, it's not the eggs themselves which experts fear will take advantage of the recent flooding.
Toads likely to hitch-hike on vehicles rather than travel as eggs
While recent flooding could cause the toad spawn to be ferried into new locations, Professor Rick Shine from Macquarie University believes it’s the adults who will likely be the bigger issue.
The toads, he says, are unlikely to hop greater distances due to torrential rain rather than regular heavy rain, but the extreme weather gives them an added opportunity.
“One of the things that happens when an area becomes wet is the toads are happy to move around,” he said.
“They tend to find their way into things like landscaping and building materials that have been left lying around.
“Now, those then get put on the back of the truck, and an ends up 1000 kilometres away in a few days time and toads suddenly have a new home.”
Professor Shine said he has seen a substantial increase in reports of stowaway toads, who have hitchhiked their way into new areas including Canberra, Taren Point in Sydney and the Central Coast of NSW.
He said there is now good evidence that toads are evolving to deal with low temperatures by physiologically adjusting their bodies.
“I think a toad dumped into a paddock in the middle of nowhere near Canberra would probably have a short and nasty life.
“But a toad dumped in the middle of town, somewhere where people are providing water, and lights at night to attract insects and things like that may well hang on for a while.”
Climate change likely to favour pest species like toads
Invasive Species Council CEO Andrew Cox said that warm, humid weather as a result of climate change is also likely to create more favourable conditions for toads.
“As climate changes over time, the southern limit will become more favourable for them,” he said.
“It’s the colder weather that’s stopping them spreading any further south - that’s the broader trend.”
Mr Cox said feral species tend to be advantaged by extremes like bushfire and floods, while native animals will often suffer a setback.
“I think there's gonna be a lot of animals moving around in these floods, and cane toads might be one of the beneficiaries of that.”
Many indigenous frogs and toads are similar in appearance to cane toads, and it is an offence to harm any native species in NSW.
Anyone who sees a cane toad or toad egg string, south of the NSW biosecurity zone is asked to immediately report it to the Department of Primary Industries.
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