Amphibians
Corroboree Frog
Pseudophryne corroboree · also called southern corroboree frog, northern corroboree frog
The corroboree frog is barely 3 centimetres long, striped in fluorescent yellow on glossy black, and it lives only in the sphagnum bogs of Australia’s highest country. It is one of the very few land vertebrates that makes its own poison rather than stealing it from prey. And it is nearly gone — reduced from tens of thousands to a few dozen wild adults by an introduced fungus.
Overview
There are two species, the southern and northern corroboree frog, both confined to a small area of the Australian Alps on the New South Wales border. They are slow-moving insectivores of the alpine leaf litter, breeding in cold sphagnum bogs. The bright yellow-and-black stripes are a warning, and the frog moves openly rather than hiding.
Poison it makes itself
Unlike American poison frogs, which extract toxins from their food, the corroboree frog synthesises its own alkaloid, pseudophrynamine, in its skin — one of the only vertebrates known to make a defensive poison from scratch.
A slow life in a shrinking place
Males call from chambers dug in wet moss; females lay a few large eggs that wait, partly developed, until autumn rain floods the nest. The frogs do not breed until about four years old and can live nine years or more, so a crashed population recovers very slowly.
Status
Both species are Critically Endangered. The southern corroboree frog is functionally extinct in the wild, down to a handful of adults, surviving mainly through captive breeding at Australian zoos with young frogs released into fungus-free enclosures. The cause is the amphibian chytrid fungus, which arrived in the 1980s, compounded by drought, the 2019–20 bushfires, feral-animal trampling, and a warming, shrinking alpine zone.
Corroboree Frog: common questions
Where does the corroboree frog get its name?
The name comes from the striking yellow-and-black striped pattern, which early European observers thought resembled the painted body decoration worn by some Aboriginal people at a corroboree, a word from the Dharug language of the Sydney region for a ceremonial gathering with dance and song. The frog itself was well known to the Aboriginal people of the high country long before it was scientifically described in 1953. There are two species, the southern corroboree frog with bright yellow stripes and the northern corroboree frog with slightly greener-yellow stripes, and they live in adjacent parts of the Australian Alps.
How is the corroboree frog different from a poison dart frog?
Both are small, brightly striped or spotted, slow-moving frogs that use warning colouration to advertise toxic skin, which is a case of similar problems producing similar solutions on different continents. The key difference is where the poison comes from. American poison frogs cannot make their toxins and instead extract alkaloids from the ants, mites, and beetles they eat, so a captive-raised poison frog on a normal insect diet is harmless. The corroboree frog makes its own poison, an alkaloid called pseudophrynamine, in glands in its skin, independent of its diet. It is one of the very few vertebrates known to synthesise rather than borrow a defensive alkaloid.
Why is the corroboree frog nearly extinct?
The overwhelming cause is the amphibian chytrid fungus, Batrachochytrium dendrobatidis, a skin pathogen that spread into the Australian Alps in the 1980s and to which the corroboree frog has almost no resistance. It killed the great majority of the population within about two decades. Several other pressures have made things worse and slowed any recovery, including drought drying out the sphagnum bogs the frogs breed in, the severe bushfires of 2003 and 2019 to 2020 burning occupied habitat, trampling of the fragile bogs by feral horses, pigs, and deer, and the long-term shrinking of the alpine zone as the climate warms. Because the frog matures slowly and lives in one tiny area, it cannot rebound on its own.
Can the corroboree frog be saved?
There is a serious, long-running effort to do so, led by Australian zoos and government agencies. Wild eggs and frogs were taken into captivity before the population collapsed entirely, and thousands are now bred each year at Taronga Zoo, Melbourne Zoo, and other facilities. Young frogs and eggs are returned to the national park, sometimes into purpose-built enclosures and artificial pools that exclude the chytrid fungus, allowing frogs to breed even though they cannot yet survive in the open bog. Researchers are also studying whether any frogs carry partial resistance to the fungus and whether that trait can be strengthened through selective breeding. For now the species persists only because of this continuous intervention.