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Carnivorous frog hitchhikes across the Nullarbor, sparking fears of eastern-states invasion

Miles Kemp, July 29, 2018 7:00PM The Advertiser

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The spotted-thighed frog which is native to Western Australia. media_cameraThe spotted-thighed frog which is native to Western Australia.


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A carnivorous* “hitchhiking” frog has invaded South Australia and scientists are calling for urgent controls to stop its spread.

The colourful spotted-thighed frog has crossed the Nullarbor by car, truck and bus from Western Australia and set up a large breeding population on the Eyre Peninsula in SA.

Frogs need plenty of water to breed and live, so it’s usually difficult for them to spread long distances across dry land such as the Nullarbor.

University of SA scientists Gunnar Keppel and Christine Taylor fear that these frogs, which have the scientific name Litoria cyclorhyncha, may reach a permanent* water supply such as the Murray River and from there spread throughout the nation.

Motorists have been warned about dangerous spotted-thighed frogs hitching a ride. media_cameraThe spotted-thighed frogs — which are dangerous if you’re a spider, insect or even a mouse — are hitching a ride across the Nullarbor. Picture: The Advertiser

In their study published in the journal Transactions of the Royal Society of South Australia, the scientists call for an urgent management plan to stop the national spread of the pests.

“We think there are about 1000 here in Streaky Bay, a population which established* very quickly, and they are a very pretty animal which can hitchhike. They are also like Houdini*, they can get in and out of any space and be transported,’’ Ms Taylor said.

media_cameraThe Nullarbor is a flat, dry plain that frogs couldn’t normally cross. The spotted-thighed frogs are catching a lift on cars, caravans, trucks and buses. Picture: istock

“If they get into Adelaide or the Murray Darling system* they will be away, they eat any animal up to a certain size, and we are worried they will also become a hybrid* with other species in the Eastern states.”

Unlike cane toads (see below), which are not native to Australia, the spotted-thighed frog naturally lives in a balanced environment in WA. Professor Keppel said the main concern with the species is that it “eats just about everything” including its own tadpoles*, spiders, insects and even small mice.

“I shudder to think what would happen if it makes it to the Adelaide Hills and the Murray Darling Basin,’’ he said.

“Definitely do not give this animal a lift and if you see it has jumped into your bag do not release it.’’

Professor Keppel said relocating the SA animals back to WA could spread disease, and culling* may be considered.

“It may come to that if there is no way of containing the frogs in Streaky Bay,’’ he said.

Ms Taylor said anyone finding the frogs should contact

Love frogs? Become a citizen scientist and help map frog species in Australia


  • Cane toads, which have the scientific name Bufo marinus, are native to South and Central America.
  • They were introduced to Australia in 1935 to control a beetle that was eating sugarcane crops in Queensland. They are very tough and prey on insects and other small animals. They are also great breeders, laying 8000-30,000 eggs at a time, compared to native frogs, which lay about 1000-2000 eggs a year.
  • Cane toads quickly spread through Northern Australia and are moving west 40-60km a year. Like other amphibians*, they prefer wet conditions, so they haven’t yet crossed the dry areas of Central Australia.
  • Cane toads don’t have predators in the Australian environment because they are poisonous to other animals to eat.
  • There is unlikely ever to be a way to properly control or remove cane toads from Australia.


media_cameraCane toads, which were introduced to Australia, are poisonous, so their numbers aren’t controlled by predators. Picture: supplied


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carnivorous: eats meat, such as insects, spiders and animals

permanent: always there, opposite to temporary

established: set up

Houdini: famous escape performer

Murray Darling system: river system across southeastern Australia including the Murray and Darling

hybrid: a combination of two things

tadpoles: lifecyclestage of frog between egg and frog

culling: reducing how many

amphibians: group of vertebrates including frogs, toads and salamanders



1. How is the frog getting across the dry Nullarbor?

2. How many could be in Streaky Bay?

3. Where is the spotted-thighed frog from?

4. What does it eat?

5. Why can’t native Australian animals prey on cane toads to keep them under control?


1. WANTED — Dead or Alive

Create a “Wanted” poster for the spotted-thighed frog. A “Wanted” poster was used in the olden days and was usually used to find criminals that police or the authorities were looking for. Your poster should contain a description and illustration of the frog and explain why it is wanted, where you might see it and what to do if you find one.

wanted poster for classroom activity, spotted-thigh frog media_cameraAn example of how wanted posters used to look a long time ago.

2. Extension: How is the spotted-thighed frog both similar and different to the cane toad?

Time: Allow 30 minutes

Curriculum Links: English, Science


With a partner see if you can you identify all the doing words/verbs in this text. Highlight them in yellow and then make a list of them all down your page. Now see if you and your partner can come up with a synonym for the chosen verb. Make sure it still makes sense in the context it was taken from.

Try to replace some of the original verbs with your synonyms and discuss if any are better and why.

QUESTION: How do you think the frogs are hitchhiking? Write a public message that tells people how and where to look for the frogs before they cross the Nullarbor.
Explain your answer using full sentences.

Extra Reading in animals