In the remote alpine waterways of northeastern Victoria, a small green amphibian with dark spots has become the focus of one of Australia’s most delicate conservation efforts. The spotted tree frog, known scientifically as Litoria spenceri, teetered on the edge of extinction for years. Now, for the first time, conservationists are reporting that individuals bred in captivity and released into the wild have survived beyond a single season.

The survival of the frogs, which were reintroduced into their native habitat over the past two years, marks a cautiously optimistic chapter in the decades-long effort to save the species. “We’ve seen encouraging signs that the frogs are not only surviving in the wild but showing early signs of establishing,” said Dr. Gerry Marantelli, a herpetologist who has worked on the species for over a decade. According to Marantelli, researchers recently confirmed the presence of several individuals at the release sites along the upper reaches of streams feeding into the Murray River system.

Historically found at high elevations in rocky creeks and riverbanks, the spotted tree frog has suffered from multiple threats, including habitat loss, introduced predatory fish such as trout, and chytridiomycosis — a fungal disease that has devastated amphibian populations globally. By the early 2000s, fewer than 250 mature individuals were believed to exist in the wild.

The recent release of captive-bred frogs was part of a coordinated program led by Zoos Victoria in partnership with the Victorian Department of Energy, Environment and Climate Action, and Parks Victoria. The effort involved years of careful habitat monitoring and targeted restoration, as well as biosecurity measures to limit the spread of disease. “This is not just about putting frogs back into a stream,” said Phoebe Burns, a wildlife ecologist involved in the release. “It’s about rebuilding an entire micro-ecosystem around what these frogs need to breed, feed and survive.”

The release locations were carefully chosen based on historic records and current water quality conditions. In particular, reaches of O’Toole Creek and White Creek, where previous populations had vanished, were among the targeted sites. These isolated headwaters provide cooler, fast-flowing conditions essential to the frog’s lifecycle.

Last summer’s record rainfall created ideal conditions for breeding, and conservationists took the opportunity to survey the area. Field teams found juvenile frogs carrying passive integrated transponder (PIT) tags — implanted before their release — confirming that some of the released individuals had not only survived but had possibly reproduced. “We don’t want to get ahead of ourselves,” Burns noted. “But finding tagged animals so many months later is evidence we’ve never had before.”

While the findings are promising, experts stress that the species remains critically endangered. Only a handful of viable habitats remain, all vulnerable to extreme weather events and further encroachment. Continued management, including predator controls and monitoring for disease, will be essential.

Still, the update offers hope for a species once written off by some as functionally extinct. “This is a long game,” said Marantelli. “But it’s a reminder that with patience, science, and good partnerships, we can turn things around — even for something as vulnerable as a frog in a mountain stream.”