Rakali, previously known as Australia’s ‘water rat’, is an important species in Australia’s aquatic ecosystems. The largest of all Australian native rodents, rakali can be found anywhere in Australia where there is water all year round; the species’ only habitat requirement is clean water and plenty of vegetation. The map here shows where rakali can be found in Australia.
This guide explains what natural habitats rakali need and how we can protect individual populations from becoming extinct.
Rakali as a species is highly durable, they can survive in most conditions, even polluted waterways. This means the species has avoided becoming endangered from the effects of the Anthropocene (human-induced changes to the climate and our environment) so far. However, populations around Australia are disappearing from areas where the habitat that rakali thrive in is being cleared or overtaken by introduced species.
The word rakali has two plural forms, so we can either say two rakali or two rakalis. Whilst the verdict on what to call a group of rakali is still out, some people believe a group of rakali should follow similar rodent species with a mischief of rakali. Others believe since it has many similarities to an otter it should be a raft of rakali. Another animal similar to rakali, the platypus, is known as a paddle of platypuses when in a group.
Photo credit: Adobe.
Rakali can grow up to around 40cm in length and weigh in at around 1kg. They are designed to live in waterways, with their webbed feet and water-resistant fur. Rakali resembles a small otter in many ways:
- Its body is elongated and streamlined, and its tail is thick and muscular to help serve as a rudder when swimming. The hind feet are partly webbed and have a broad palm for efficient paddling.
- The ears are small and can be folded flat against the head, and the muzzle is blunt and furnished with a dense set of long whiskers.
- The fur repels water, drying quickly once animals exit the water.
Rakali are less selective than other native animals, like the platypus, with their prey and they forage primarily underwater. Their diet includes fish, aquatic insects, crayfish, crabs, mussels, clams, aquatic plants and even frogs, turtles, birds and bird eggs.
Rakali have niche characteristics that give them survival advantages over other native animals. They are semi-aquatic, meaning they can hide from terrestrial predators in waterways as well as on land. They are nocturnal, but when needed can also often be found scavenging during daylight. They live in burrows on the edges of rivers, lakes, estuaries and protected coastal beaches and islands – the key requirement is a permanent body of water. Rakali can even be spotted in inner cities, such as alongside the penguins at St Kilda beach pier in Melbourne!
Rakali in Australia’s ecosystem
Rakali play an important role in ecosystems. One way is by dispersing fungi spores which assist plants to extract water and nutrients from the soil. Rakali eat the fungi and spread it around the soil through their droppings. Australia’s soil is nutrient-poor and ancient, so the fungi helps introduce nutrients, particularly phosphorous and nitrogen, and promotes native plant growth and resilience to diseases and droughts.
Rakali helping our native species – hunting invasive species
A 2019 study (Parrott et.al) into rakali and invasive cane toads showed that rakali in Northern Australia have adapted to be able to prey on cane toads. The invasive cane toad species, native to South America, is a huge threat to many native flora and fauna. Many would-be predator species are unable to consume the cane toads due to the toxins found on the skin of the toads. The rakali have been able to overcome this by adapting the way it attacks and consumes the toad. The study found that the rakali has learnt, most likely through adaptation over time from dealing with toxic native frogs, to peel back the toxic skin of the toad in order to consume the internal organs, which are not toxic for rakali. Surprisingly, the study also found that rakali tend to go for larger cane toads, compared to smaller ones. It is unknown exactly why they prefer to kill larger pest cane toads, but it is likely that smaller ones move quicker so larger ones are easier to capture.
Rakali have also been spotted tackling introduced carp fish!
Interesting facts about rakali
FACT #1: The name ‘water rat’ was phased out during the 1990s with a push from the Australian Nature Conservation Agency. It was believed ‘water rat’ held negative connotations for the animal and harms any conservation movements to protect it. In 1995, the Agency proposed the name rakali, used by the Ngarrindjeri people in the lower Murray River and Coorong region of South Australia to be used as the species’ common name.
FACT #2: Rakali have a different name in almost every language group in Australia and Papua New Guinea.
FACT #3: Rakali are more similar to otters in their behavior, than beavers or rats as they were intitially compared to when European settlers first came to Australia.
FACT #4: Rakali are commonly found in similar habitats as another native Australian animal, the platypus. The two species face similar threats, with their habitats often under threat.
FACT #5: Another threat that rakali face is hunting, which has been banned since the 1950s. During the 1930-40s, rakali were almost hunted to extinction as their waterproof fur was used by upper-class Australians for coats and hats.
FACT #6: Rakali often come into contact with humans and they can be spotted around urban waterways. They are known to raid goldfish ponds or poultry yards, kill free-ranging guinea pigs in gardens, steal bait and snacks from anglers, deposit piles of fish bones on the decks of moored yachts, or leave the remains of cane-toads near swimming pools.
Rakali face many threats including predation by introduced animals, such as cats, foxes and some native birds of prey, as well as habitat degradation and loss. Rakali’s natural habitat is threatened by the effects of land use changes for agricultural and urban development. Changes in natural river hydrology from river regulation and dams have also had a significant impact on their environment, often pushing rakali into polluted urban waterways.
Rakali have relatively short lifespans of two to three years and low reproduction rates, with just two to four pups in an annual litter between spring and summer. This means large changes in their habitat, usually resulting from droughts, floods or habitat degradation, can result in large localised declines in rakali populations.
Rakali and riparian zones go together
Rakali build grass-lined nests at the entrance to their burrows which are usually hidden among vegetation, and built at the end of tunnels in banks of rivers and lakes. Rakali need healthy riparian vegetation and solid river banks, with minimal erosion. Rakali consume their prey on flat feeding sites such as logs, rocks or sheltered areas on the river bank, returning to these sites for each meal.
Intact riparian areas provide connectivity and habitat for rakali, which is essential as these animals are often solitary. Large populations need large connected riparian areas to sustain their individual habitats. Riparian zones are important for both land and water ecosystems, and native species in riparian areas. Our Rivers of Carbon approach shows how connectivity between riparian zones is essential for all riparian species.