Eastern Banjo Frogs
'Bonk, Bonk, Bonk' Sounds in the Garden?
If you're spending the evening near a big pond or lake at this time of year, the distinctive calls of the Eastern Banjo Frog may serenade you.
The noise can either be charming or extremely annoying, depending on how much you want to get to sleep! Click here to watch and listen to the Eastern Banjo Frog.
Like nature’s own bluegrass band, once the Banjo Frogs get going, you’d swear you were hearing musical instruments, rather than a pudgy 8 cm long amphibian looking for love.
Instead of a croak, their call is a resounding ‘bonk!’ It is usually repeated every few seconds, but sometimes the whole gang will get together to produce a rapid series of ‘bonk bonk bonk bonks!’ running together. This has led to their nickname, the Pobblebonk.
There are five subspecies of Eastern Banjo Frog, but the most familiar has light brown skin, heavily mottled with dark brown or steel grey. This subspecies can be found living in waterways, backyards and even children’s’ sandpits across inland New South Wales, northern Victoria, and along the Murray River in South Australia. Other subspecies vary in colour and live in south-east Queensland, the Snowy Mountains, and Tasmania.
Heavy rains across much of eastern Australia cause Banjo Frogs to leave their usual haunts and move about the countryside in search of a mate. The breeding season will last from August through to April, and during this time you will hear their familiar call.
As the frogs become ready for mating, the male develops a dark yellow or green throat, while the female grows large flaps of skins, called flanges, on the first two fingers. Most of the action takes place in or around the pond. The male calls while he is floating out in the open water. The real show-offs call from inside a burrow to amplify the sound.
After mating, the female lays a large white floating raft of eggs, looking for all the world like a sago pudding. Anything from 500 to several thousand pigmented eggs are within the foam which is usually tucked underneath waterplants to hide it from predators.
This is not a species that lays its eggs and runs off. There is parental care involved. Using the large flaps of skin on her fingers, the female carries air bubbles from the surface of the water into the foam nest to keep the eggs oxygenated.
When the tadpoles hatch, they are dark brown and spotted. They can take up to 15 months to metamorphose into frogs, depending on the temperature. Frogs in Tasmania, for example, might take longer to mature.
Once they have turned into frogs, they will be old enough to strike up their own band and play their unique ‘song’ late into the night to begin a whole new generation.
DID YOU KNOW?
Banjo frogs are quite warty, and can sometimes be mistaken for cane toads. It’s best to take a close look before jumping to conclusions or taking drastic action. Banjo frogs are large by frog standards (up to 8.5cm) but cane toads are much larger - up to 15cm. Both have warty skin but the toad is dry, while the frog is moist. You can recognise a toad by large poison glands behind the ears, a pointed bony ridge between the nose and eyes, and visible eardrums.
In toads the back feet are webbed, while frogs hind feet are unwebbed so they can dig into the ground and bury themselves.
Domestic pets will prey on frogs, so keep cats and dogs inside at night. Avoid using garden chemicals as they can contaminate frog ponds and destroy the homes of frogs and tadpoles. Remove exotic fish such as goldfish, and Gambusia from backyard ponds. These fish will eat frog eggs and attack tadpoles. Don’t touch frogs or move them to a different pond. This could spread a disease called chytrid which can be fatal to frogs.