RADICAL’S SONGS

Rats belong to the Order Rodentia, ie rodents.

When Australia finally separated from Antarctica around 45 million years ago, the only land mammals were monotremes (echidna and platypus) and marsupials (forerunners of kangaroos, possums, etc). Placenta animals like rats and mice were not part of her compliment.

As Australia drifted north, between 10 to 15 million years ago, the first wave of land based placental animals arrived; these were the bats, later followed by the rodents between 5 and 10 million years ago. The bats had flown in, and presumably the rodents drifted in on rafts of vegetation from Indonesia. This first immigration of mice-like rodents are known as the ‘old endemics,’ and these evolved into our distinctive endemic rodent species, like the water-rat, melomys, rock-rats, hopping mice, etc.

The second immigration known as the ‘new endemics’ arrived around two million years ago and were the first rodents from the genus Rattus.
Bush Rats are nocturnal and secretive and rarely seen day or night, so catching the one below emerging from vegetation was a very lucky coincidence.

From a common Rattus ancestor, seven distinct Australian species evolved, of which Rattus fuscipes the Bush Rat is one. Two other Rattus species, R. rattus the Black Rat, and R. norvegicus the Brown Rat, along with Mus musculus, the House Mouse, have arrived within the past few hundred years via either the First Fleet and European settlement in 1788, or by earlier shipwreck. So Rattus fuscipes, the bush rat although a relatively recent addition, is a truly Australian native species and occurs nowhere else.

There are four subspecies of Bush Rat, but the species as a whole, is geographically distributed from east of the Divide in Queensland, NSW and Victoria, along with some near coastal areas of SA. It is not found in the more arid Nullarbor region, but reoccurs at Esperance, WA, then around coastal areas to a little north of Perth. It also occurs on many offshore islands, but did not gain a footing in Tasmania.

Interestingly, the bush rat is not found on the Mornington Peninsula (Victoria) either, despite being common in forests immediately to the north. In this area the Swamp Rat, Rattus lutreolus is common, as is also the case in Tasmania. There is unlikely to be a significant species conflict as the swamp rat is commonly found with the bush rat over most of its east coast range. Although the Bush Rat has a preference for forest areas, whist the Swamp Rat the more open country around swamps and heathland. In WA where the swamp rat does not occur, the bush rat Rattus fuscipes subspecies fuscipes, occupies these swamp and heathland zones and is often called the Western Swamp Rat.

The soft fur and long whiskers of this WA Bush Rat give it a very cute look.

The indigenous Australian rats do not carry infectious diseases as do the introduced species, they keep themselves meticulously clean with regular and thorough grooming, plus do not feed on carrion (decaying flesh). It’s a matter of opinion, but most people find the Bush Rat a lot cuter that the introduced species.

To the uninitiated the bush rat can be mistaken for the introduced black rat, however there are several distinct differences. The bush rat has long soft fur and tends to look a little chubby, whilst the black rat’s fur is shorter and the animal appears long and sleek. Tail length in relation to head/body length is markedly different, with the bush rat’s tail being about the same length, whilst the black rat’s tail is unmistakably much longer than its head/body length. Although bush rats can climb simple structures, it is primarily a ground living animal, however the black rat is an excellent climber. So if a rodent is raiding your fruit trees, or living in your roof, it is highly likely to be the introduced black rat.

Bush Rats build an underground tunnel system and can usually be recognised by a mound of excavated soil. Large snakes like the Dugite frequent these areas for rat tucker, plus will seek shelter in the burrows during bushfires or to hibernate through winter. The bush rat is very much a vegetarian, but will also eat fungi and insects, so is a highly adaptable species and capable of surviving changes to its habitat, although it is not successful in urban areas. This is probably because it is a ground living species and its burrow is easily located, making it highly susceptible to cat predation.

The teeth are not discolored, but are covered with orange/yellow enamel.

Our indigenous rats and mice are beautiful creatures and should not be confused with the often smelly and destructive introduced rodents. If you have some of our native species living near you, then you are very fortunate and you should ensure they have a chance to prosper by not clearing undergrowth and ensuring cats are excluded from the area.