The 13 finger nail-sized Maud Island froglets were discovered clinging to the backs of full-grown male frogs at the Karori Wildlife Sanctuary in the capital Wellington, said researcher Kerri Lukis. The frogs are normally found only on two islands in the Malborough Sounds region of New Zealand's South Island.
"Maud Island frogs have never been found breeding" before, even on their home island, said Lukis, a masters degree student at Victoria University in Wellington.
"It's wonderful timing for 2008 - International Year of the Frog and a Leap Year," she said.
The breeding suggests Maud Island frogs can be bred in other predator-free habitats - strengthening their prospects for survival, said Ben Bell, the biologist overseeing Lukis' studies.
The sanctuary's predator-proof fence gives the frogs a breeding environment like Maud Island that is safe from rats, Bell said.
Maud Island frogs are estimated to number up to 40,000 - most of them on the island from which they take their name and the rest on Motuara Island.
Don Newman, who is the threatened species science manager with the Conservation Department and was not involved in the frog program, said the breeding success adds a third location where the frogs have bred, a factor that "spreads the risk" and improves the species' chance of survival.
Maud Island frogs, one of four native New Zealand frogs, have evolved little over the last 70 million years, Lukis said, resulting in distinctive features and behaviors.
They do not croak, live in water or have webbed feet, she said.
Also unlike other frogs, these hatch from the egg as fully formed frogs without going through the tadpole stage.
Eggs are laid under rocks or logs and the male sits over the eggs until they hatch as well formed, tailed froglets.
In 2006, 60 Maud Island frogs were released in the frog enclosure at the wildlife sanctuary - a security-fenced area of some 620 acres set up to enable threatened native birds and other species to re-establish their numbers safe from introduced predators like rats, mice, stoats, ferrets and wild cats.
All four of New Zealand's surviving native frog species are threatened, with the rarest, Hamilton's frog, numbering less than 300.
