The Rakali, our native Water-rat

Australia has two amphibious mammals: the iconic Platypus and the Rakali.

Recently, there seems to have been a spate of sightings of Rakali around Merri Creek, especially around dusk, or early in the day, as they forage around in the water and clamber in and out of the banks where (like Platypus) they burrow. It’s a shy creature, so patience and keeping still is required to observe them.

Rakali is a Ngarrindjeri word from the First Nations people of the south-east corner of South Australia and the south-west corner of Victoria. They are also known as the Golden-bellied or Australian Water-rat, native Otter or by its scientific name of Hydromys chrysogaster. Hydro obviously meaning water, mys meaning mouse, chryso meaning golden and gaster meaning belly.

Rakali depend on permanent water bodies, which may be fresh or brackish. They have a remarkably large range from Tasmania, Victoria, New South Wales, Queensland, South Australia and the Northern Territory and the south-west and the north of Western Australia, right up into Papua and Papua New Guinea. It is thought that the original population swam, or rafted, from Papua to colonise the south around five to ten million years ago.

They are an easy mammal to identify, with a distinctive and diagnostic white tip to its thick long tail. An adult can weigh up to 1.3 kg, has long, sharp front incisors, a flat head with a blunt nose and dense whiskers to enable it to detect underwater prey, small ears that can be folded back against the head for streamlined swimming, webbed hind feet and beautiful water-repellent fur that is cream to yellow-golden on the belly.

It was this fur which made the rakali such a target for hunters in the 19^th and early 20^th century, until they were given full protection in the 1950s. They are now deemed non-threatened in terms of conservation status. However, scientists also acknowledge difficulty in studying the Rakali and their true numbers due to their reclusive nature and ability to avoid or escape live traps by using those sharp teeth.

Rakali feed on a wide range of prey, including large insects, crustaceans, mussels and fish (native and introduced), frogs, lizards and even water birds! Once the prey is caught underwater, they take them to regular sites to eat. I have seen piles of clamshells heaped on particular flat rocks and wondered. There are also reports that Rakali in some northern areas of their range have worked out how to safely eat cane toads! It is thought that Rakali can live up to four years of age and may produce up to three litters a year.

Of course, being dependent on water makes Rakali vulnerable to water quality and habitat degradation caused by our propensity to drain and clear wetlands and alter waterways for various purposes and, of course, the effects of climate change. In addition, although no longer hunted by humans, foxes and cats take their toll.

Hopefully, with the work MCMC is doing to establish more protected areas around the Creek and the proposed new wallan wallan Regional Parkland, we can maintain the non-threatened status of the Rakali for a good while longer! In this way, we can ensure more regular encounters on quiet dusk or dawn walks on the Merri.

Brazenor, C. W. (1950). The mammals of Victoria: and the dental characteristics of monotremes and Australian marsupials,
Handbook Number 1, National Museum of Victoria, Melbourne: Brown, Prior, Anderson, p 64

References:

Water-rat, Australian Museum
Updated 14/04/26 and accessed 21/4/26
Distribution and status of the Australian Water-rat/Rakali in the greater ACT region, Australian Platypus Conservancy
Accessed 21/4/26
Marissa Parrott, Sean Doody, Simon Clulow, Eat your heart out: native water rats have worked out how to safely eat cane toads, The Conversation, 23 September 2019.
Accessed 26/4/2026