More than 500 critically endangered frogs have been released in a national park as part of efforts to save them from extinction.
The northern corroboree frogs were bred at Sydney's Taronga Zoo before being released in Brindabella National Park, west of Canberra.
It's estimated as few as 1200 of the frogs remain in the wild, with 544 bred in captivity before being released in the park.
They weigh about three grams and are roughly the size of a paperclip, but the black and yellow amphibians play an important role in Australia's sub-alpine ecosystem.
The calls of previously released frogs have been heard in the wild, proof they can thrive after leaving their captive-breeding environment.
"This is the largest frog release within this population to date," Taronga Conservation Society Australia conservation officer Michael McFadden said.
Future releases are planned to help bolster the survival of the species, which is only found between 750-1800m above sea level along mountain ranges in NSW and the ACT.
The frogs were bred as part of NSW government program to prevent endangered species from going extinct and is among other "rewilding" efforts taking place around the nation.
The process involves restoring habitats and re-introducing captive-bred threatened species to the wild in a bid to reduce biodiversity loss.
Quolls previously extinct on mainland Australia have been re-introduced in feral-free sanctuary zones, as well as Tasmanian devils.
Platypuses, bettongs and bilbies have also been reintroduced in recent years to areas where they previously become extinct.
