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A unique type of pygmy crocodile found only in Australia could be wiped out by the dreaded cane toad unless prompt action is taken, zoologists have warned.
Just two populations of the endangered pygmy freshwater crocodile are known to exist, both of them in the country's tropical north.
The crocodiles are at risk because they prey on cane toads and then die from the amphibians' highly toxic skin.
Isolated in remote rivers and creeks by waterfalls and steep sandstone escarpments, they are about half the size of normal freshwater crocs.
The campaign to save the pygmies is being led by a British zoologist. In a field of science which could scarcely be more Australian, Yorkshire-born Dr Adam Britton is an expert on crocodile conservation and research.
He fears that without prompt action, the toxic toads could wipe out the pygmy crocodiles, which may constitute a separate sub-species or even species.
The reptiles are found in two known locations around the Bullo River, on the border of the Northern Territory and Western Australia, and in the Liverpool River in Arnhemland, on the opposite side of the Northern Territory.
Their population is believed to be in the low hundreds, making them highly vulnerable to extinction.
But time is already running out. Cane toads have invaded the Liverpool River, but it is so remote that scientists have no idea how badly they have affected the crocodile population.
Wildlife volunteers have found nearly a dozen dead freshwater crocodiles in the region in recent weeks, all of which died after eating cane toads.
The Bullo population of pygmies is in the middle of the toads' advance.
"We need to establish if the pygmies are genetically different from normal freshwater crocodiles, but either way they are unique," said Britton.
While normal freshwater crocodiles grow up to 3m, the pygmies reach barely half that length. Researchers have found adult females which measure just 70cm.
The cane toads' march has been relentless since a small group was released into Queensland in the 1930s. They have hopped across the Northern Territory and are poised to invade neighbouring Western Australia.
Dr Britton believes the only hope of saving the rare crocodiles is to set up a captive breeding programme at a cost of up to A$200,000 ($229,000). Neither the Northern Territory nor federal governments has agreed to provide funding.
