Snowgums in winter in the Australian alps ©Getty Images

Snowgums in winter in the Australian alps ©Getty Images

Australia's tiny southern  corroboree frog of is one of the most striking frogs in the world. It is listed as Critically Endangered. 

'Corroboree' (say kuh-rob-uh-ree) is a word in an Aboriginal language (there are many) that is the name of a social gathering with singing and dancing.  

Frogs are amphibians,      which means part of their life cycle is spent in water. 

Habitat and Distribution (where they are found)

©Getty Images

©Getty Images

The southern corroboree frog is only found in a very small area (about 400 sq kms) of snowgum woodlands and sphagnum bogs in Kosciuszko National Park in New South Wales, one of the coldest parts of the Australian mainland.  

Sphagnum is a kind of moss that holds a great deal of water, like a sponge. The moss is an important part of water catchment in the alpine regions, and essential for the corroboree frog.

The corroboree frog is found only at altitudes above 1300 metres. There are just 3 main populations of the frog: the Snowy Mountains, Fiery Range and the Brindabella Range.

Appearance

The corroboree frogs from the Fiery and Brindabella Ranges have lime or yellow and black stripes. Those in the Snowy Mountains region further south have brighter yellow stripes.

The pattern of each frog is different. The frogs are tiny. Adults grow to about 25 mm. They do not have webbed feet.

Diet

Young frogs, called froglets, eat beetles, bugs, ants, insect larvae and mites. The adults mostly eat ants, but also eat beetles and mites.

Life cycle

Frog with eggs in sphagnum moss nest. The eggs look like clear marbles. ©Getty Images

Frog with eggs in sphagnum moss nest. The eggs look like clear marbles. ©Getty Images

The corroboree frog has a very different life cycle  from that of other frogs. They don't start breeding until they are 3 or 4 years old, and they don't lay their eggs in water.  

Adults hibernate through winter amongst the  snowgums, hiding under fallen leaves, bark, grass, rocks and logs. In December (early Australian summer), the males travel to pools surrounded by sphagnum moss for summer breeding,  unlike most other frogs which breed in spring. They dig a small burrow in the sphagnum moss for mating and nesting.   When the burrow is finished a male starts calling to attract females and to tell other males of his presence.  The sound made by the adult male corroboree frog is rather like when you run a wet finger over a blown up balloon.  

He will attract up to about ten females, one at a time. Inside the burrow each female lays up to 38 eggs (unlike other frogs, this is a small number. The eastern banjo frog for example, lays up to 4000 eggs).  As the eggs are laid, the male sheds sperm directly onto the eggs, which means they are fertilised and young will grow in them. A male stays in his nest most of the summer, trying to attract numerous females,  and builds other nests if the first fills with eggs.

Corroboree frogs in sphagnum moss ©Getty Images

Corroboree frogs in sphagnum moss ©Getty Images

Each egg looks a bit like a marble, made of a jelly-like substance. They enlarge quickly, absorbing large quantities of water so they don't dry out during summer.

The tadpoles develop in about 4 weeks but, unlike other tadpoles, they stay in their egg jelly for about 6-7 months. The tadpoles are 6 mm long and grow very slowly until they finally hatch out of the jelly in autumn.  

When the autumn rains fall, the water level of the pool gets higher and floods the nest. This seems to be the signal for the tadpoles to hatch out of the jelly and slither into the water. All winter they remain as tadpoles, even under the ice when the pool freezes.

 A year after the eggs were laid, as summer warms the water, the tadpoles change. First they grow back legs then front legs, then their tails disappear. They are now froglets about 8mm long, and they leave the nesting pools to travel to find places among the snowgums to hibernate through the winter.

Snow gum in summer landscape ©Getty Images

Snow gum in summer landscape ©Getty Images

Conservation Status and Threats

The corroboree frog is Australia's most endangered frog. The cause of the decline is not clear, but may include a number of factors:

  • human activity such as 4 wheel drive vehicles destroying nesting grounds and the development of ski resorts;
  • climate change and global warming: corroboree Frogs have adapted to the cold, and winters may now not be long and cold enough for them to breed effectively;
  • depletion of the ozone layer may play a role by increasing the ultra violet rays shining on shallow pools;
  • disease: many frogs in Australia and overseas are affected by infections caused by a fungus;
  • erosion and pollution of waterways used for breeding.

The risks for the corroboree frog are increased by the very small area they inhabit and their specialised breeding pattern. Females breed only once a year, and the tadpoles are slow growing, spending many months in the shallow pools, which makes them vulnerable.

Actions to try and save the corroboree frog

The New South Wales National Parks and Wildlife Service and others are observing and testing to try and find the reasons for the frog's decline. The Amphibian Research Centre is attempting to rear frogs from eggs in laboratories, aiming for the eventual release of adults back into the habitat.

 

Read more about the corroboree frog and watch videos:

http://www.arkive.org/corroboree-frog/pseudophryne-corroboree/

Find out about the Amphibian Research Centre's Project Corroboree:

http://frogs.org.au/corroboree/index.html

Read the kidcyber page:

Threatened Species