Introduction
To most people, a rat is one of the undesirable introductions to Australia by the early settlers. There are however, many Australian native rats; placental mammals that produce live young in an early stage of development. These rats entered the continent in relatively recent times; long after the arrival of marsupials, but still long before Europeans and the introduced Black and Brown Rats arrived. Despite the dominance of marsupials in Australia, many of our native rats successfully established themselves in a range of habitats.
A Bush Rat
Photographer / Source: Gary Lewis
The Bush Rat, Rattus fuscipes, is a small compact mammal with an average length of 310 mm (160 mm body + 150 mm tail) and an average weight of 160 grams. The fur is soft and dense, varying from grey brown to reddish brown above and grey to light brown below. The tail length is shorter than the head and body length, which is a useful diagnostic feature. It can be separated readily from marsupials by its typical paired, yellow-orange faced, upper and lower incisors.
Where do they occur?
Bush Rats are common throughout much of coastal mainland Australia. There are several sub-species, of which the best known is Rattus fuscipes assimilis from the south-east. It occurs in a wide range of habitats from sub-alpine heaths to coastal scrub, wherever there is dense ground cover, but it is absent from the Mornington Peninsula. It prefers a vegetation cover of shrubs and ferns.
What do they eat?
Bush Rats have a mixed diet, which includes insects and vegetation such as leaves, fruit, seeds and fungi. This diet aids its survival under such adversity as bush fires. It can survive periods of food shortage after a bushfire by feeding on the rapidly emerging fungi.
What is their breeding cycle?
The Bush Rat of the southeast is capable of breeding in all seasons, but as a rule does not breed in winter. The usual litter size is five, and in a good season a number of litters may be produced. From a birth weight of about 5 g, the young become independent when they are about four weeks old, and are capable of breeding in the wild at about four months of age.
What is their conservation status?
Bush Rats are widespread and common and are secure in suitable habitat.
Further Reading
Menkhorst, P. and Knight, F. (2001). A field guide to the mammals of Australia. Melbourne: Oxford University Press.
Menkhorst, P. (Ed.) (1995). Mammals of Victoria. Oxford University Press. Melbourne
Strahan, R. (Ed.) (1995). The Mammals of Australia. Reed. Chatswood. N.S.W.