The spotted tree frog was already recovering from local extinction when the “Black Summer” wildfires of 2019 to 2020 raged through New South Wales (NSW) in Australia. Of 250 to 300 frogs once released into the wild, only about 10 survived.
But now, the critically endangered species is receiving yet another lease on life. The government has released 80 spotted tree frogs into Kosciuszko National Park.
“Releasing these 80 Spotted Tree Frogs back into the wild despite all the setbacks this species has faced is a reminder to have optimism about the conservation work we’re doing, because it’s clearly making a positive difference,” NSW Minister for Environment James Griffin said in a press release.
The spotted tree frog (Litoria spenceri) is a medium-sized amphibian that lives alongside mountain rivers in the Australian states of NSW and Victoria, according to the Victoria state government. The females are slightly larger than the males, growing to around 60 millimeters in length, and have a dappled olive-gray and green skin that helps them blend in with streamside vegetation.
“The Spotted Tree Frog is fundamental to the maintenance of ecosystem health in the NSW upland rivers where it lives,” Department of Planning and Environment senior threatened species officer David Hunter said in the press release. “It occupies many streams where they are the only frog species, and tadpoles of this species consume nutrients and algae in large numbers. They are also food for other species such as snakes, birds, mammals and predatory invertebrates, playing an important role in the food web.”
Australian Museum amphibian biologist and conservationist Dr. Jodi Rowley told The Sydney Morning Herald that the frogs were bioindicators, meaning that it is possible to use them as a proxy for the overall health of their environment.
“They are the glue that sticks ecosystems together. In places where frogs have had dramatic declines there are nothing that steps up to fill that role,” she said. “There are irreversible changes: the streams are full of algae because the tadpoles aren’t there to eat it, animals that rely on frogs waste away. We need frogs.”
However, the frogs have been struggling for years because of chytrid fungus. Scientists have called this amphibian-targeting fungus “the most destructive pathogen ever,” and it has already driven 90 species to extinction in the last 50 years.
The spotted tree frog itself became extinct in NSW in 2001 because of the disease, but the NSW Government’s Saving our Species program and the Amphibian Research Centre in Melbourne worked together to breed the frogs and re-release them beginning in 2015, the NSW government said. In Victoria, the species is no longer found in half of the sites it previously inhabited, and the government says it will go extinct without help, The Sydney Morning Herald reported.
In addition to the fungus and threats from the climate crisis such as bushfires, the frogs also face pressure from introduced predators like cats and foxes. However, scientists are hopeful that they can give the frogs the support they need.
“To have these 80 frogs back in the wild, and hopefully thriving and helping boost their population numbers, is fantastic,” Rowley told Australia’s ABC News. “It’s one of the most threatened frog species in Australia and it’s holding on, just clinging on, thanks to these amazing conservation works.”