A notable little Australian
Rats belong to the Order Rodentia, ie rodents. So what, I hear you say? Well so do around 50% of all mammal species, so these are a highly successful group of animals. Of the twenty odd families in Rodentia, rats and mice belong to the family Muridae, along with voles, muskrats, lemmings, hamsters, etc, and collectively make up 25% of all mammal species. The remaining families contain a very diverse range of animals from beavers to porcupines, squirrels to prairie dogs, etc.
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.
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.
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.