Scientists hop to it to save a special frog

An adult giant burrowing frog (Helioporus australiacus). Photo: Mike Swan
An adult giant burrowing frog (Helioporus australiacus). Photo: Mike Swan

GUIDED by a specialist team of threatened species scientists, Melbourne Zoo frog experts have ventured into the depths of Victoria's forests to collect tadpoles from one of the state's most mysterious frog species.

The giant burrowing frog (Heleioporos australiacus) is a large frog, chocolate brown above and white beneath, with scattered yellow spots.

It has never previously been held and bred in captivity, and remains one of Victoria's most cryptic frogs.

Records of the giant burrowing frog are scarce in Victoria, with the species' known habitat limited to remote parts of central and east Gippsland.

Other, potentially genetically distinct, populations are found in southern New South Wales.

To secure the giant burrowing frog's future, the conservation program hopes to conserve healthy populations of the species in the wild, and captive populations are a key element of that strategy.

Last month Zoos Victoria scientists joined Arthur Rylah Institute threatened species scientists leading the wild conservation program to collect tadpoles from wild habitats in a remote part of east Gippsland.

These tadpoles were transported to Melbourne Zoo and are the founders of the first-ever captive conservation program for the giant burrowing frog.

The research team's initial goals are to study how the tadpoles grow into adult frogs and to build skills for a future breeding program.

Much of the range of the giant burrowing frog was devastated by the 2019-20 Black Summer bushfires.

But researchers working in the field have found evidence of limited and highly localised egg laying, prompted by recent higher-than average rainfall across Gippsland.

Frog experts collect wild giant burrowing frog tadpoles from east Gippsland to begin a captive breeding program at Melbourne Zoo. This species was affected by last summers bushfires.

Frog experts collect wild giant burrowing frog tadpoles from east Gippsland to begin a captive breeding program at Melbourne Zoo. This species was affected by last summers bushfires.

Zoos Victoria threatened species biologist Deon Gilbert says this had given researchers a rare opportunity to jump-start their conservation program.

"This species breeds in shallow pools and, unfortunately, the pools can dry out really quickly depending on the weather," he said.

"This year, unlike many others, we have had a lot of rain in early spring and summer, and that has produced really good conditions for giant burrowing frogs, so we were lucky enough to find some tadpoles, and that's what has instigated this program," Mr Gilbert said.

"It's incredibly exciting to work with an amphibian we know so little about.

"The first goal of the program is just to figure out what makes this species tick.

"We know almost nothing about its wild ecology or its captive biology.

"So we need to figure out how to grow them, rear them and produce really fit frogs.

"And then those frogs will go on to start a conservation breeding program."

While the future of the giant burrowing frog, like many other frog species, is likely threatened by the devastating chytrid fungus, wild populations of the giant burrowing frog are also under pressure from habitat loss caused by land clearing, logging, climate change, increasingly frequent and severe bushfires, and feral cats and foxes.

"Unfortunately for this species the threats are pretty numerous," Mr Gilbert said.

"It's always been incredibly rare and now, given the threats it faces, even more so."

Melbourne's Zoo's amphibian team has already had great success breeding two other rare frog species, the critically endangered Baw Baw frog and southern corroboree frogs.

Late last year, a group of adult Baw Baw frogs was released at the species' wild home on Mt Baw Baw for the first time.

The Melbourne Zoo team has also bred corroboree frog eggs for wild release for several years.

The giant burrowing frog project has been supported by donations to the Zoos Victoria Bushfire Emergency Wildlife Fund.

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