Amphibians
Southern Corroboree Frog
Pseudophryne corroboree · also called southern corroboree frog
The southern corroboree frog is a tiny, brilliantly striped frog from the bogs of the Australian Alps — yellow and black like ceremonial body paint. It makes its own poison, it lives nowhere else on Earth, and there may be fewer than fifty of them left in the wild.
Overview
The southern corroboree frog lives only in sub-alpine bogs, wet heath, and woodland above about 1,300 metres in the Snowy Mountains of Kosciuszko National Park, New South Wales — a range of a few hundred square kilometres. It is small (2.5–3 cm), boldly striped in bright yellow and black, and slow: it does not breed until it is four years old. Males call from moss and sphagnum, guarding eggs in a nest that waits for autumn rain or snowmelt to flood it; the tadpoles then develop through winter.
Its own poison
Corroboree frogs were the first vertebrates shown to make their own alkaloid toxin — pseudophrynamine — rather than only sequestering it from prey like poison dart frogs do. The warning colours advertise it.
Near-extinction
The amphibian chytrid fungus, arriving in the Australian Alps in the 1980s, has caused a decline of over 99%. The frog has almost no resistance, and its slow breeding, tiny high-altitude range, and few breeding bogs left no room to recover. Numbers fell from thousands of calling males to a few dozen frogs. Feral horses and pigs, drought, and a shrinking alpine zone add pressure.
Kept alive by hand
The species survives mainly through an intensive zoo breeding programme holding several thousand frogs and eggs as an insurance population, with captive-bred releases into protected bogs, disease-exclusion enclosures, and research into chytrid resistance.
Status
Critically Endangered — fewer than 50 mature adults thought to remain in the wild.
Southern Corroboree Frog: common questions
Why is it called a "corroboree" frog?
The term is an Anglicised word for a ceremonial gathering with song and dance among Aboriginal Australian peoples, and it was applied to the frog by early naturalists because its bold yellow (or yellow-green) and black striping resembles the ochre body-paint patterns worn for such ceremonies. There are two species — the southern corroboree frog covered here, which is brighter yellow, and the northern corroboree frog, which is more yellow-green — and both are small alpine frogs from the mountains of southeastern Australia, and both are among the most endangered amphibians in the country.
How is its poison different from a poison dart frog's?
Poison dart frogs and mantellas are toxic because they collect alkaloids from the ants and mites they eat and store them in their skin; raised on other food in captivity, they become non-toxic. The corroboree frogs were the first vertebrates shown to make their own alkaloid poison — a compound called pseudophrynamine — biosynthesising it from scratch in their skin glands regardless of diet. (They will also take up dietary alkaloids from ants when available, so they use both routes.) The toxin makes the frog distasteful and is advertised by the warning colours, though it is not dangerously potent to humans.
Why has the southern corroboree frog almost gone extinct?
The overwhelming cause is the amphibian chytrid fungus (Batrachochytrium dendrobatidis), which reached the Australian Alps in the 1980s. The southern corroboree frog has essentially no resistance to it — infected frogs die, and because the frog breeds slowly (not until age four), lives in a tiny high-altitude range, and gathers at a small number of bog breeding sites, the population had no capacity to absorb the losses. Numbers fell from thousands of calling males in the 1980s to a few dozen frogs today. Feral horses and pigs damaging the bogs, drought drying the breeding pools, past logging and grazing, and climate change shrinking the alpine zone are additional pressures, but chytrid is the killer.
What is being done to save it?
The species survives largely because of an intensive captive-breeding programme run by Australian zoos (Taronga, Melbourne, Healesville, and others) since the 2000s, which now holds several thousand frogs and eggs as an insurance population. Captive-bred eggs and frogs are released back into the wild at protected bog sites, some fitted with disease-exclusion enclosures, and researchers are working on chytrid mitigation — including trials of "assisted selection" for more resistant frogs and treatment of release sites. The southern corroboree frog is, in effect, a species being kept alive by human intervention while a solution to chytrid is sought.