Bringing Frogs Back from the Brink

Zoos Victoria’s new Amphibian Bushfire Recovery Centre is fighting to save three rare native frog species.

WORDS Susan Horsburgh

Australia’s frogs had been under attack for years – from climate change, land clearing and pollution, introduced species like trout, feral cats, foxes and hoof stock, not to mention the deadly chytrid fungus, which has destroyed amphibians across the globe – but then came the Black Summer bushfires of 2019–20. Fires razed more than 1.5 million hectares of Victorian bushland and choked streams with ash, decimating already endangered frog populations.

Now at crisis point, the amphibians have been thrown a lifeline thanks to the Australian Government Bushfire Recovery Program for Wildlife and their Habitats, and the Zoos Victoria Bushfire Emergency Wildlife Fund. A state-of-the-art frog-breeding facility has been built at Melbourne Zoo to save three rare species: the Spotted Tree Frog, Watson’s Tree Frog and Southern Giant Burrowing Frog. “Impacted by the fires, it’s even more crucial now that we set up recovery programs,” says Zoos Victoria Amphibian Specialist, Damian.

Constructing the centre

To design the breeding terrariums for the Amphibian Bushfire Recovery Centre, Damian has spent many years studying these frogs in their natural habitats to understand what they require to stimulate breeding behaviours. “All the information we absorb out in the wild we bring back to the Zoo and simulate on a smaller scale, so the frogs feel comfortable in their microhabitats,” he explains.

“We have full control of the climate in these new facilities and rely on other frog biologists who collect important data, which informs us what temperatures the frogs require to thrive. We create seasonal changes which helps stimulate reproduction. It’s important that we put these sub-alpine species through a wintering brumation period. In spring, we increase the temperatures and create rain events via a sprinkler system, which sparks the males into calling. Once they’ve attracted a female, they’ll then go into amplexus [the mating embrace] and hopefully produce a healthy clutch of eggs.”

The new facilities are bio-secure to protect these sensitive species from pathogens. The centre features airlocks (where the keepers don gloves, overalls and gumboots) and the hygienic enclosures have everything frogs need to thrive. “We grow live plants and have installed an automated irrigation system that keeps their home clean by flushing away any biowaste through a perforated mesh elevated floor, providing good drainage” explains Damian.

Lighting is also important. Large windows provide the frogs with natural photoperiods. Artificial lighting is also connected to a photocell to mimic the seasonal daylight hours. As frogs require UV lighting to sustain healthy development, programmable LED lights are used to stimulate the growth of plants, which provide moist retreats for the frogs.

Boosting genetic diversity

The goal is to ensure genetic diversity and to selectively breed frogs that are resistant to chytrid fungus. As these insurance captive populations grow, the frogs will be released back into their wild habitats to help boost populations.

HOW TO BE FROG-FRIENDLY

More than 150 Southern Giant Burrowing Frogs, successfully reared from tadpoles at the Zoo, have already moved into the new centre. This is the first time this species has been established in a zoo. Big enough to cover the palm of your hand, the stocky, slow-moving frog sounds like an owl hooting. According to Damian, the charismatic species creates burrows near streams and broadcasts its calls through a chimney of sorts.

Pulling the frogs back from the brink of extinction, he says, is vital:

“We’re lucky to have a unique diversity of frogs in Victoria and listening to the soundscape of frogs calling – it would be devastating to lose that,” says Damian. “Frogs keep our water systems in check and are an important biological indicator of environmental health. They’re also a crucial part of our ecosystem and food chain. Without frogs, many other species would suffer and die off.”

Saving nature’s gems

For Damian – who’s been fascinated by amphibians since he rescued tadpoles from his family’s swimming pool as a child – the new breeding program is a thrilling development for conservation.

The Spotted Tree Frog is one of Zoo’s Victoria’s Fighting Extinction species and a new challenge for the team to breed in captivity. “Coming across them at night, is like spotting a tiny bright-green gem sitting on a leaf,” Damian says. “I’ve had a fair bit to do with them in the wild, so breeding them in captivity so that we can help save the remaining wild populations … this challenge has got me very excited.” ZN

Detergents