Green and Golden Bell Frogs Return to Australian Wetlands After 45-Year Absence

For the first time in more than four decades, a striking amphibian once thought lost forever from the region around Australia’s capital is making a triumphant return. The green and golden bell frog, a species known for its brilliant emerald coloring accented with golden stripes, is being carefully reintroduced to wetlands in the Australian Capital Territory after vanishing from the area around 1981.

The return marks a significant milestone in amphibian conservation, demonstrating how creative scientific approaches can help reverse even the most dire population collapses.

A Fungal Threat and an Innovative Response

The green and golden bell frog’s disappearance from the ACT can be traced to chytrid fungus, a pathogen that has caused extinctions and severe population declines in amphibian species across every continent. The fungus attacks the skin of frogs and other amphibians, disrupting their ability to absorb water and electrolytes, ultimately proving fatal to many infected individuals.

But researchers at the University of Canberra refused to accept the frog’s local extinction as permanent. Their solution combines old-fashioned captive breeding with remarkably clever environmental engineering.

More than 300 frogs have been bred in captivity and immunized against the chytrid disease before their release. The animals are being introduced in groups of 15 across various ponds and wetlands surrounding Canberra, with the goal of establishing populations of approximately 200 frogs at each of 15 different sites.

Frog Saunas and Spa Retreats

Perhaps the most inventive aspect of the reintroduction program involves specially constructed heated shelters that researchers have affectionately dubbed “frog saunas.” These structures consist of black bricks arranged and covered with rigid plastic sheets in a pyramid formation. The dark materials absorb sunlight, creating warm microenvironments within the slots and holes of the bricks where frogs can shelter.

The genius of the design lies in the biology of the chytrid fungus itself. According to Associate Professor Simon Clulow, the pathogen becomes vulnerable at elevated temperatures and cannot survive conditions above 27 to 28 degrees Celsius. The green and golden bell frog, meanwhile, actually prefers temperatures around 30 degrees Celsius—approximately 88 degrees Fahrenheit—making the heated shelters perfect havens where the frogs can thrive while the fungus perishes.

A total of 180 of these sauna structures have been installed around the release ponds, providing the newly freed amphibians with ready access to protective warmth.

The release sites themselves were also carefully selected based on lessons learned from wild populations that have managed to survive elsewhere in Australia. Outside the ACT, isolated groups of green and golden bell frogs have persisted in pools containing slightly saline water. Scientists have identified similar locations near Canberra, referring to these ideal habitats as “frog spas” for their combination of warm, gently salty water and nearby sauna accommodations.

A Population Poised to Flourish

While the initial release involves just over 300 frogs, the population has strong potential for rapid growth. Each female green and golden bell frog can produce approximately 8,000 eggs during a single mating season, meaning the reintroduced population could expand dramatically within just a few years.

There is one important consideration: while the released adults have been immunized against chytrid, their offspring will not carry that same protection. This reality makes the frog saunas even more critical to the program’s long-term success, as future generations will rely on the heated shelters to help them combat the ever-present fungal threat.

For the scientists who have nurtured these amphibians from eggs to adults in captivity, the moment of release carried deep emotional resonance. Associate Professor Clulow described watching the frogs venture into their new wetland homes as “quite incredible,” likening the experience to watching children leave home for the first time.

Hope Springs Eternal

The return of the green and golden bell frog to the Australian Capital Territory represents more than just a successful breeding program. It demonstrates that thoughtful, science-driven conservation efforts can bring species back from the brink of local extinction, even when facing persistent environmental threats.

As these vibrant amphibians settle into their new wetland homes, complete with spa-like conditions and personal saunas, they carry with them the hopes of researchers and wildlife enthusiasts alike. Forty-five years after their disappearance, the distinctive calls of green and golden bell frogs may once again become a familiar sound in the evening air around Canberra—a small but meaningful victory in the ongoing effort to protect the planet’s remarkable biodiversity.