Sydneysiders: don’t step on the red-crowned toadlet


Bec Crew


Bec Crew

Bec Crew is a Sydney-based science communicator with a love for weird and wonderful animals. From strange behaviours and special adaptations to newly discovered species and the researchers who find them, her topics celebrate how alien yet relatable so many of the creatures that live amongst us can be.
By Bec Crew 4 July 2022
Reading Time: 2 Minutes Print this page
Sydney, it’s your time to shine, because this beautiful little frog has made its choice. Found nowhere else on Earth except a tiny pocket in the Sydney Basin, the red-crowned toadlet (Pseudophryne australis) is a rare sight to see, so it’s worth knowing what to look (and hear) for.

A member of the Pseudophryne genus of frogs, the red-crowned toadlet is among several species of myobatrachid frog, a group found in Australia and New Guinea.

Myobatrachid frogs range from less than 1.5 cm long to more than 10 cm, such as the giant barred frog (Mixophyes iteratus), which, at 12 cm long, is one of Australia’s largest. The red-crowned toadlet, by comparison, is just 3 cm long.

Myobatrachid frogs are known for carrying out some fascinating parenting care, such as the mouth-brooding behaviour of the gastric brooding frog (genus Rheobatrachus), known to harbour its young inside its mouth. It’s feared that Australian species of gastric brooding frog are now extinct.

Then there’s the pouched frog (Assa darlingtoni), also known as the hip-pocket frog, found in parts of New South Wales and Queensland, which has pouches on the sides of its body to transport its tadpoles after hatching.

Related: Frog in a bog

The red-crowned toadlet, meanwhile, is a bit more ‘hands-off’ when it comes to parenting.

These frogs are found exclusively in sandstone escarpment areas around Sydney, their range extending from Ourimbah in the Central Coast to the north, to Nowra in the south and the Blue Mountains to the west. They lay their eggs in clusters under moist leaf litter or inside small logs, gutters or rocks – wherever rain water might collect – guarded fiercely by the males.

Once it rains, the nests will flood and the tadpoles will finish their development and hatch. If the rain doesn’t come for a long time, the tadpoles will slowly develop, which means they can hatch anywhere from one to six months after being laid.

Given how tiny they are, red-crowned toadlets aren’t easy to find, but once you spot one, they’re pretty easy to identify, given their distinctive bright red or orange markings. They’ve also got interesting marbled patterns on their bellies:

A red-crowned toadlet.
Photo credit: Nature Picture Library / Alamy

If you’re in the presence of one of these frogs, you’ll most certainly hear it before you see it. The call of the red-crowned toadlet is described as short, grating and “squelchy”, and can be heard year round, typically after rain.

Sadly, these frogs are in serious decline; they are currently classified as vulnerable to extinction. A big factor is their sensitivity to pollution – they have not been recorded breeding in waters that are even mildly polluted or with a pH level outside 5.5 to 6.5.

The good news is that researchers and the public are helping to keep tabs on the fate of these wonderful little frogs. Back in 2020, the call of the red-crowned toadlet was the 200,000th verified record submitted to the Australian Museum’s national FrogID project.

It was submitted by frog-enthusiast Tom Kristensen, from southern Sydney, who used the FrogID app to learn to distinguish different frog calls.

“I’m now recognising individual frogs calling and hearing these new frogs joining in,” he told the Australian Museum. “It’s all quite exciting, but even more thrilling is the knowledge that these calls are made by a species of frogs listed as vulnerable to extinction.”

Learn more about the FrogID project, and hear the red-crowned toadlet’s call here.

Related: Australian frogs are dying en masse again, and we need your help to find out why