Rattus lutreolusAustralian swamp rat

Geographic Range

This species is common over a wide area of south-eastern Australia. One subspecies is also found on the north-eastern cosat (Strahan 1995).


Rattus lutreolus prefers poorly drained habitats, heathland, and sedges. This species has also been found on dry ridges in open forest. Density of vegetation seems to be the most important requirement of this species. This is most likely a result of selection for evasion of avian predators, or perhaps because food is more abundant in dense habitats. Habitat selection by females is most likey related to the amount of energy required for reproduction. Members of this species can survive without free water (Haering and Fox 1995, Monamy 1995, Strahan 1995).

Physical Description

Head and body length of this species ranges from 122mm to 197mm and the tail length is an additional 56-147mm. Rattus lutreolus is dark gray or gray brown on its dorsal surfaces and cream to brown on its ventral surface. The fur on the upper half of the body is golden-tipped. Its ears are small and nearly concealed by hair. The tail is dark gray, scaly and sparsely haired (Strahan 1995).

  • Average mass
    115 g
    4.05 oz
  • Average basal metabolic rate
    0.353 W


The breeding season is generally from early spring to autumn, but breeding can occur throughout the year. The gestation period is three weeks and the female gives birth to three to five young, each weighing approximately 5 grams. A female may produce several litters in a year and a three month old female from an early spring litter may be reproductively active that same year. Females are usually aggressive toward males except during mating (Monamy 1995, Strahan 1995).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
  • Average gestation period
    27 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    79 days


  • Typical lifespan
    Status: captivity
    1 (high) years
  • Range lifespan
    Status: wild
    2.4 (high) years


Not much is known about the social systems of this species. Females are aggressive toward males. Females maintain territories in spring and males wander until winter. At that time males maintain a territory of their own in order to survive the winter (Monamy 1995, Strahan 1995).

Communication and Perception

Food Habits

Stems and leaves are the main foods eaten by R. lutreolus. In spring and early summer, their diet expands to include seeds, fleshy fruits, and insects. Roots and underground fungi are also consumed by R. lutreolus (Cheal 1987, Norton 1987).

Economic Importance for Humans: Positive

The swamp rat was hunted by Aborigines prior to European settlement and provided a significant source of meat;however, this hunting pressure no longer exists (Strahan 1995).

Conservation Status

Rattus lutreolus is common throughout its limited range. Most of its original habitat has now been farmed and made unsuitable for this species (Strahan 1995).


Cindy Felcher (author), University of Michigan-Ann Arbor.



Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


Cheal, D.C. 1987. "The diets and dietary preferences of Rattus fuscipes and Rattus lutreolus at Walkerville in Victoria." Australian Wildlife Research 14, 35-44.

Haering, R. and B.J. Fox. 1995. "Habitat utilization patterns of sympatric populations of Pseudomys gracilicaudatus and Rattus lutreolus in coastal heathland: A multivariate analysis." Australian Journal of Ecology 20, 427-441.

Monamy, V. 1995. "Population dynamics of, and habitat use by, Australian native rodents in wet sclerophyll forest, Tasmania." Wildlife Research 22, 647-660.

Norton, T. 1987. "The ecology of small mammals in north-eastern Tasmania." Australian Wildlife Research 14, 415-433.

Strahan, R. (ed.). 1995. "Swamp rat." Mammals of Australia. Washington D.C., Smithsonian Institution Press.