Some of Australia's most endangered frogs are chilling out for a while.

The 18 adult Corroboree Frogs at Melbourne Zoo are experiencing a cold snap for a few weeks before the breeding season begins.

They will be living in specially-designed containers in a fridge for the next four to six weeks.

Keeper Raelene Hobbs explains that as an alpine species, these frogs experience low temperatures in the wild, so a brief period at between 5.3 and 8.6 degrees is beneficial to the breeding program.

Melbourne Zoo is the first zoo to breed Corroboree Frogs and is a member of a cooperative breeding program for the species.

There are currently three Corroboree tadpoles on view in the World of Frogs. Another four tadpoles that developed from the two nests of eggs laid in the autumn have already developed into metamorphs - these tiny froglets are only 8mm to 9mm long.

Adults are also very small, only about 4cm long, but they are still spectacular, thanks to their shiny black and gold colouration.

Raelene will bring the frogs out of the cold in December, when the males are due to build nests and start calling to attract the females. Breeding and egg laying take place in February and March.

Raelene explains that ‘the eggs take up to two months to mature into the larval or tadpole phase of the frog life cycle. They spend about nine months as tadpoles, including an over-wintering period.

‘In spring they begin to metamorphose into tiny young frogs, but they take three to four years to mature and be able to breed.'

The most recent survey of this species in the wild located only 50 to 60 individuals, so this is an extremely significant cooperative breeding program.