Our Other Platypus

Image: Nolan White

Most Australians are comfortable with the knowledge of our native marsupials they acquire around primary school age. Most Australians could comfortably name a species or two of kangaroo and wallaby. Most would be able to recall a time when a possum became a nuisance. And at a pinch, some may be able to distinguish monotremes from marsupials.

But if you ask an Australian about rodents, the response you are likely to get is some form of ‘yuck’. Rodent usually equals introduced critters with a penchant for growing into plague proportions and spreading infection. It is true, we have five species of introduced rodents: House Mouse, Black Rat, Brown Rat, Pacific Rat, and (fun fact) the Five-lined Palm Squirrel, a zoo escapee species established in Perth. Chances are, however, that you would be surprised if I told you we have nearly 50 species of native rodents – more than 50 if you count the extinct critters. For instance, the Spinifex Hopping Mouse lives in elaborate burrow systems in close family groups, and is an incredibly sophisticated desert specialist species. And for an extinct example, the White-footed Rabbit-rat – ‘gnar-ruck’ to the Eora people – was a kitten-sized, squirrel-like Conilurus species which used its semi-prehensile black and white tail to craft grass nests in among the eucalypts from Adelaide to Sydney. All 47 extant species are uniquely adapted to their Australian ecosystem homes, and contribute to the ecosystem functioning and biodiversity of this wide brown land.

I recently shared a piece on Facebook about the Rakali, the largest species of native rodent. This post was met with two comments. The first read, ‘one of Australia’s most underrated mammals.’ Thumbs up, totally agree. The second said something to the extent of, ‘this is disgusting, I can barely type this response because I don’t want to look at it.’ Wot?

Well, my friends, it’s time to buckle up, because I am about to challenge the latter sentiment with some non-alternative facts.

The Rakali (also known as ‘water-rat’) is a top aquatic predator, akin to an otter, which deftly hunts for fish, amphibians, crustaceans, and occasionally land mammals. They are gorgeously well adapted to their environment with webbed feet, sensitive whiskers for detecting prey and a water-resistant coat in golden-orange and charcoal coloration with a white-tipped tail.

This lovely coat meant that the Rakali was hunted towards the point of extinction for their pelts, particularly in the 1930s when importation of overseas furs was banned. In 1943, the Rakali was protected from hunting. Human activities, however, continue to have a detrimental impact on the Rakali. Many drown in yabby and crayfish traps, and others are actively killed by fishermen who perceive the Rakali as a pest that will steal their bait or catch. Anecdotally, they have been known to steal pet food from suburban backyards, as well as fish and chip scraps from lake edges. Misinformed local beach and lake goers try to injure Rakali, falsely thinking they are righteously removing a rat from the area.

Rakali are seen fairly regularly in Lake Burley Griffin, particularly at the eastern inlet of the Molonglo River, as well as in Lake Ginninderra. I can recall one particular half-moon Friday night, eating a Yarra kebab on the edge of the lake, with a Rakali spreading ripples across the pensive surface, as it leisurely paddled through reflections of street lights above.

Despite the manufactured and degraded water quality of our water systems, Rakali continue to persist in the Canberra region. The introduced Common Carp makes up an estimated 90 percent of the fish biomass in some regions of the Murray-Darling Basin. Carp have many impacts on their environment – reducing water visibility, promoting algal blooms, contributing to erosion and spreading diseases – but they also impacts predators like Rakali and Platypus by competitively feeding on invertebrates . Additionally, Carp reduce native fish numbers, but this effect is poorly understood.

Not very much is known about the Rakali, as they are a shy, solitary species. In an ABC news interview, Dr Melody Serena from the Australian Platypus Conservancy said, ‘we are relying heavily on feedback from the public about whether water rats have disappeared from their local area … They are charming little animals and ecologically very important.’ As a top predator, the Rakali controls aquatic populations – in particular crustaceans like yabbies – which in high numbers would threaten the structural integrity of mud banks with their burrowing. Professor Peter Banks from the University of Sydney is currently investigating how Rakali supress the invasive Black Rat population by outcompeting the feral species. Incredibly, the Rakali is also known to eat Cane Toads by flipping them onto their belly to avoid contact with the toxic glands.

So, keep an eye out around Canberra’s lakes next time you go for a jog, cycle, early morning adventure or late night snack run. You might just see the cryptically gorgeous Rakali ottering about.

If you see the Rakali, please send a detailed description and location information to the Australian Platypus Conservancy at platypus.apc@westnet.com.au or check out their Facebook page, Australian Platypus Conservancy (Official).