The endangered Southern Corroboree Frog at Melbourne zoo.

An endangered corroboree frog. More than 300 eggs bred at Melbourne Zoo will be released in the Kosciuszko National Park. Photo: Wayne Taylor

A FOAM Esky will be the unlikely vessel carrying the young of one of Australia's most endangered species from Melbourne Zoo to the alpine marshlands of Mount Kosciuszko next week.

Inside the Esky will be five plastic tubs each containing 60 black eggs. Resting on moss like jewels on velvet, the precious eggs belong to the striking black and yellow southern corroboree frog.

With fewer than 100 southern corroboree frogs remaining in the wild, the species' critically endangered status means slumming it in an Esky is unusual. Normally this is a species which enjoys the Rolls-Royce treatment.

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These eggs started life at Melbourne Zoo's $75,000 amphibian centre, a purpose-built climate-controlled facility which is playing a key role in the captive breeding program in Victoria and New South Wales.

And although they will travel to their new alpine address in an Esky, it will be a helicopter which drops them at their remote mountain-top home on Tuesday.

Amphibian keeper Raelene Hobbs said while the zoo had been participating in a national recovery program for the species since the mid-1990s, it was the first time Melbourne Zoo had released corroboree frog eggs into the wild.

Given the dire results of the most recent ''frog census'' taken during breeding season, it's a tactic researchers are hoping will pay off. Between December and April, researchers recorded just nine males calling in the wild and found just one clutch of eggs. ''It probably means there are barely any females left in the wild,'' Ms Hobbs said.

One of the main threats to the frog's survival in the wild is the water-borne disease chytrid fungus, which attacks the keratin in the animal's skin cells. Because frogs breathe through their skin, infected frogs die from asphyxiation. After releasing frogs and tadpoles in the past, researchers are hoping a new approach might help pull the wild population from its precarious position.

''The eggs can't get chytrid fungus because they don't have keratin,'' Ms Hobbs said.

''If we continue to release … then evolution might happen in front of our eyes and hopefully the metamorphs might be able to build up a resistance.''

The 300 eggs bred at Melbourne Zoo during March and April will be released with about 19 from Healesville Sanctuary and 500 captive-bred eggs from Sydney's Taronga Zoo.

The eggs will be released at three carefully selected sites into 4-degree water and Ms Hobbs said some were so swollen, they would hatch within the first 24 hours.

However, because the frogs only reach sexual maturity at age four or five, the effect of introducing eggs to the wild population will take years to measure.

''Really though, we have to release them now because they are going to be extinct in three or four years if we don't,'' she said.

The southern corroboree frog only occurs in the Snowy Mountains region of Kosciuszko National Park between 1250 and 1750 metres above sea level. The small ground-dwelling frogs measure no more than three centimetres long. They do not hop, but clamber over their mossy habitat.