Zookeepers at Auckland Zoo are claiming a massive and internationally important victory after a critically endangered Archey's frog successfully bred from a long-term captive population.

Seven Archey's frog babies that hatched at the zoo in December from fertile eggs laid in October are continuing to thrive, keepers said. Auckland Zoo is the only facility in the world to hold the frogs.

While Archey's frogs have been bred twice before elsewhere in captivity, the babies did not survive.

"It's a massive step forward to finally breed these enigmatic and extremely sensitive little frogs after almost eight years," Auckland Zoo NZ Fauna curator, Richard Gibson, said.

International experts agreed the breeding of Archey's frogs is a huge achievement.

Kevin Zippel, programme director of the Amphibian Ark  - a world body focused on the global survival of amphibians - said: "Conserving any species usually requires a whole range of actions and captive breeding is increasingly a requirement for many threatened amphibians. Auckland Zoo's recent success with Archey's frog is exciting news and represents an important breakthrough".

Professor Jonathan Baillie from the Zoological Society of London said "breeding one of the most primitive and threatened species on the planet is an amazing achievement and a major breakthrough for conservation". 

Archey's frogs, like New Zealand's other three endemic frog species, don't have a tadpole stage that other members of the species have. Instead, the Archey's tadpole grows limbs inside the egg, and then hatches out as an almost fully formed frog. 

The seven baby frogs, each just a half a centimetre long, have absorbed their yolk sacs and progressed to a diet of tiny invertebrates, keepers said.

While not currently on display, visitors to Auckland Zoo will soon be able to see adult Archey's frogs in the zoo's night forest habitat within its New Zealand precinct, Te Wao Nui.

- © Fairfax NZ News