Wednesday, July 04, 2007

Bush Rat, Rattus fuscipes

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.

Bush Rat, Rattus fuscipes

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.

Unfortunately the bush rat below was killed accidentally when it climbed into the engine compartment of my car, however note the chunky look due to its long soft fur.

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. I may be a little bias, but they are also much better looking.

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.

A gloriously soft tummy.

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 need of a bush habitat, is probably because it is a ground living species and its burrow 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.


Gaye from the Hunter said...

What a delightful creature :)

Recently while visiting the New England National Park (NSW), I encountered some rat-like creatures. I think one was an antechinus, and I think the other was a species of Rattus fuscipes. This was the first time that I have encountered any native rat-like creatures, and it was a wonderful experience.

Your description of the bush-rat vs the introduced black rat is valuable for novices to attempt to distinguish the differences.

The chubby little fella emerging from its hole certainly is a cutie.

Thank you for sharing your knowledge and appreciation of your neighbours.


Esperance Blog said...

Thanks Gaye, I think all our mammals are little cuties.

Anonymous said...

I live in Melbourne and noticed 2 little creatures feeding on dusk on some parrot seed that had dropped from our feeder. They were small and quite like the description you have given here except upon observing them I noticed they hopped. They sit back on their hind legs like a tiny kangaroo and hopped to get to and from their small clearing in some low lying thick shrubs we have in our backyard. The fact that they hopped confused me, do bush rats hop? And is it likely that they live in suburbia as we do? Thanks.

WA said...

Hi Anonymous,
I know Melbourne quite well, and what native animals you may have would depend on where you are. You would need to be near a chunk of native vegetation that has dense cover. It does not need to be all native, but a fair potion of it should be, and likely a little overgrown so the animals can gain environmental protection from cats and foxes.

So unless you are near a creek or the Yarra, or on the outskirts, they are very likely to be introduced rats/mouse (you did not give an indication of size) as these often hop when moving short distances.

If you are on the Mornington Peninsula it could be a Swamp Rat (native) as Bush Rats do not occur down there. So you would need to be to the northeast of Melbourne to get a Bush Rat.

However a likely possibility is the Bandicoot that does hop when moving around. These however are larger than a rat or a mouse, unless a juvenile. If a bandicoot it will have a very short tail.

Please let me know if you think you have something of interest along with details of your location.


Sherrie said...

Thanks for the great photo's and description. I was able to identify the bush rat quite clearly, compared to the black rat.



Janet James said...

HI - We live on Molloy Island in WA and also think this little creature is very cute. Unfortunately it is also quite a nuisance!
We have had one/or more visiting our shed which I have to say is VERY untidy! This tiny little thing has checked out every plastic container, drilling a tiny hole in the side but often in the bottom so the contents leak out! It's best effort was to take a circle of plastic from the top of a large bottle of oil and somehow drop the float down into the oil and then sit there tasting said oil and then escape. Amazing.
We have tried all methods of catching it but plastic traps are no challenge - it eats it's way out. Last night I caught it in a wire rat/possum trap with small chicken wire but it still managed to escape.
We don't mind sharing it's habitat if it would only stick to native vegetation!
Regards Janet