Nothing beats the rakali, Australia's mighty native water rat

Australia Broadcast Center

15 hours ago

Whether it's hunting invasive pests or rolling in a river like an otter, there's a lot to love about the rakali ( Hydromys chrysogaster ).
The nation's biggest rodent is perhaps its most resourceful having adapted to urban, mountainous and coastal habitats around the country.
All these traits and more have seen the rakali crowned the nation's most underrated animal in the ABC's National Science Week poll.
Its landslide win even took some rakali researchers like Antia Brademann by surprise.
Ms Brademann is currently monitoring rakali at Bush Heritage Australia's Scottsdale Reserve, south of Canberra.
"As a rakali fanatic myself, I wasn't sure the Australian public would respond to the call to elect a rat as our most underrated animal," she said.
"But right around the country people have spoken and the rakali is finally getting its moment in the spotlight — proof that being a furry little water ninja with webbed feet and a taste for cane toads pays off."
And rightly so, according Dr Ann Jones host of What The Duck?! on ABC Radio National.
"The rakali is worthy of this crown. It is more than a rat — it is the ruler of all the rats."
"It's widespread but secretive, it's fluffy but a kick-arse fighter, it surprises and delights observers, and its very presence repels introduced black rats out of its territory.
Rakali live in many environments
While it might look like a large rat on first glance, the rakali has a white-tipped tail and, across most of its habitat range, yellow belly fluff. This is even reflected in its scientific name — chrysogaster — which means "golden belly" in ancient Greek.
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The rodent's diet is extremely varied. Mostly, it will eat shellfish, fish and other aquatic animals, but it has been known to also try its hand at catching birds that get too close to the water.
It can co-exist in the same habitats as platypus. But the wily rat has better adapted to more degraded habitats, like urban waterways, than the duck-billed monotreme.
A rakali on a beach at K'gari (Fraser Island). ( iNaturalist: Tommi Mason, Rakali, CC BY-NC 2.0 )
Rakali can get by in a range of environments including coastal locations like the beach at K'gari (Fraser Island). ( iNaturalist: Tommi Mason , Rakali , CC BY-NC 2.0 ) Rakali have adapted to live in urban environments. ( iNaturalist: Jens Sommer-Knudsen, Rakali, CC BY-NC 4.0 )
Urban environments. ( iNaturalist: Jens Sommer-Knudsen , Rakali , CC BY-NC 4.0 ) Rakali swimming in the Tarra Valley which is part of Victoria's Strzelecki Ranges. ( iNaturalist: Scott Rolph, Rakali, CC BY-NC 4.0 )
And in mountainous areas like Victoria's Strzelecki Ranges. ( iNaturalist: Scott Rolph , Rakali , CC BY-NC 4.0 )
Charles Sturt University ecologist Emmalie Sanders said rakali didn't need a lot to get by.
"They're resilient, they're everywhere, they don't need a great deal, they can survive in pretty low-quality water," she said.
These wildlife warriors can kill invasive pests
In a recent study in Australian Mammalogy, researchers found the rakali may act as a natural deterrent to feral rats in some areas.
The study detailed the ambush of an invasive black rat in Sydney by a rakali, which was captured on a camera trap.
Just like the polarising ibis, Ms Sanders said the rakali had figured out how to devour invasive and toxic cane toads without dying.
"[Rakali] can sense prey moving with their whiskers," she said.
"They usually mange to flip [toads] and consume them from the belly where they don't have those poisonous glands."
Like surgeons, rakali carefully make an incision into the stomach of the toads.They then remove and eat the heart and liver.
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They've survived the fur trade (and a re-brand)
But the native rodent wasn't always a hunter — in fact, it was previously the hunted.
During the 1900s, when a Bubonic plague broke out around the country, a bounty was put on rats to try to limit the spread of disease. We know that at least some rakali were killed.
Rakali were once known as the "beaver-rat" and their water repellent coat was collected in the 1930s when there was a ban on imported furs.
The policy change saw the price of a rakali fur jump from 4 shillings in 1931 to 10 shillings (about $50 today, adjusted for inflation) a decade later.
But they are one of many native rodents that have undergone a PR revision to distance themselves from the associations of "rat" or "mouse".
A massive rebrand started a year before the start of the fictional TV crime show Water Rats about Sydney's water police.
Back in 1995, the Australian Nature Conservation Agency (now called Parks Australia) started a campaign to change the name from the "water rat" to "rakali", the animal's Indigenous name used by the Ngarrindjeri people from the lower Murray River in South Australia.
Three decades later, the name has stuck — but it's not the only one.
Because the rakali is found throughout the country, there are many more Indigenous names for the nation's favourite underrated animal.
There are different types of rakali
Whether the rakali is just one animal is a divisive question.
Early colonial naturalists thought there were 16 subspecies of the creature, but research in the 1980s and 1990s disputed these descriptions and suggested there was just one Australian species.
An 1863 lithograph of the typical 'golden-bellied' rakali from John Gould's book The Mammals of Australia volume 3. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia )
John Gould's third volume of The Mammals of Australia in 1863 included what was then believed to be four species of rakali including the "golden-bellied beaver-rat". ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia ) An 1863 illustration of a Fulvous beaver rat, later redesignated as also being a rakali. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia )
The "fulvous beaver-rat" was described as an orange-furred animal in South Australia but was later considered a member of one species, the rakali. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia ) An 1863 illustration of what was thought to be the white-bellied beaver rat but is now considered a rakali. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia )
The "white-bellied beaver-rat" from the Hunter and Clarence Rivers, NSW, was also redescribed as a rakali. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia ) An 1863 illustration of a sooty beaver rat which was later redesignated as a rakali. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia )
Finally, the "sooty beaver-rat" from WA was another animal to fall under the rakali umbrella. ( Biodiversity Heritage Library: Henry Constantine Richter/The Mammals of Australia )
Genetic studies have brought a greater understanding of the history of rakali populations around Australia and their origins.
Rodents first arrived in Australia about 5 million years ago, but rakali are a more recent arrival having been here for about 1 million years.
Tasmania has the oldest lineage of rakali and may represent the earliest spread of the species from New Guinea. There is also significant genetic divergence between populations from Tasmania, south west WA, Barrow Island (off the northern WA coast) and the rest of the east coast.
The colour of their cute bellies changes as well. Rakali on Barrow Island have silver-grey coats, south west WA specimens are mostly black, while golden-bellied morphs dominate the eastern states.
Rakali from south west WA don't have any gold on their belly and instead have a mostly black coat. ( Supplied: DBCA/Karen Bettink )
Although rodents have been in Australia for a long time, they don't attract the same reverence as mammals like marsupials.
That's despite about one third of the country's 60 rodent species going extinct or suffering massive reductions since European colonisation.
How you can look after our rakali
There's still so much we don't know about the rakali, including whether any of these distinct populations are under threat of extinction.
Ms Sanders hopes to find out more about the plight of the species, although working with rakali isn't without its challenges.
"They've been difficult to track," the ecologist said.
"[In] any radio-tracking studies that are done, they are notoriously good at getting out of their little collars that we put the transmitters on."
A rakali in Canberra eating a fish. ( Flickr: Duncan McCaskill, Rakali, CC BY-NC 2.0 )
Rakali love to hunt for fish. ( Flickr: Patrick Kavanagh , Rakali , CC BY 2.0 ) A rakali perched on a rock eating a shellfish. ( iNaturalist: Ron Greer, Rakali, CC BY-NC 4.0 )
The rodent is clever enough to pry open shellfish. ( iNaturalist: Ron Greer , Rakali , CC BY-NC 4.0 ) A rakali eating a shrimp. ( iNaturalist: Ron Greer, Rakali, CC BY-NC 4.0 )
Other marine invertebrates, including shrimp, are also target species. ( iNaturalist: Ron Greer , Rakali , CC BY-NC 4.0 )
But Meg Shaw, an environmental behaviour researcher at Monash University said there were still a number of things people could do to protect the rakali on a local scale.
"One of the key threats to rakali is being entangled in fishing line and nets, so you can actually report sightings of illegal fishing nets to CRIMFISH, or there are other authorities within your state," she said.
"They are also predated on by dogs, cats and foxes, so the recommendations are to try and keep cats and dogs away from waterways where rakalis could be."
Two rakali swimming in Cecil Hoskins Nature Reserve, NSW ( iNaturalist: Jacqui Davey, Rakali, CC BY-NC 4.0 )
Finally, she said it was important to ensure cars drive slowly around rakali habitats, particularly at night when it's harder to see and more rakalis are out and about.