Surprise discovery of bleating frog in Victoria

By Natalie Muller 13 May 2011
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The bleating tree frog, thought to inhabit only NSW, has been discovered in Victoria.

A FROG SPECIES PREVIOUSLY thought to inhabit only Australia’s east coast has been discovered in Victoria.

For the first time, the bleating tree frog (Litoria dentata) has been found at three floodplains along the Genoa River near Mallacoota in East Gippsland. This is more than 40 kilometres away from the nearest known population in northern NSW.

Ecologist Dr Graeme Gillespie was surveying frog populations in the Genoa River Valley for the Department of Sustainability and Environment, when he heard the distinctive call of the bleating tree frog amid a cacophony of seven other frog calls.

He says it is unlikely the frogs moved downstream during the recent flooding; rather, he believes they have been there all along.

“The reason [this species] has gone unnoticed in the area until now is probably because no one with knowledge of its call has been there to hear the frogs when they are breeding,” Graeme says. “This is more likely to be a relic population, or an isolated population, that’s gone undiscovered in Victoria for some time.”  

He says the discovery highlights the limited understanding of distribution of frog species in Australia.

Frog colonies possible all over Australia

The floodplain area where the species was found in Victoria is almost the same type of habitat chosen by the NSW population.

Professor Ross Alford, a herpetologist at James Cook University, says there’s a strong chance the species could also be found in similar habitats around the country. He says there have been many new species found in the last 15 years, just by researchers going out and looking.

In 2008, Ross was part of a group at JCU that rediscovered the armoured mist frog (Litoria lorica), a critically endangered species from far north Queensland that hadn’t been seen in 17 years.

“We were beginning to think it was extinct, but it was just that no one was looking outside the rainforest habitat,” he says.

The researchers discovered the species also favoured habitats near cool streams and running water outside rainforest areas. Ross believes more new species will emerge as researchers learn more about the distribution, habitats and genetics of frogs.

Screeching Frog

The bleating tree frog species is not listed as threatened in Australia, but they are tricky to study, especially outside breeding season, Ross says. “They are surprisingly difficult to find, and as with most frog species, we know almost nothing about what they are doing when they’re not breeding,” he says.

The bleating tree frog is secretive, often hiding in small spaces and only hunts at night. But the distinctive call, heard by Graeme in the Genoa River Valley, is often what gives them away. Their screeching call is loud, high-pitched, and sounds more like a cicada than a frog, but it is usually only heard after heavy rain or on warm nights.

Graeme expects that with thorough surveys, more frog species will be added to the Victorian list in the future.