Nature conservation

Threatened species

Mastacomys fuscus mordicus - profile

Indicative distribution

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The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.
Scientific name: Mastacomys fuscus mordicus
Conservation status in NSW: Vulnerable
Commonwealth status: Vulnerable
Gazetted date: 24 May 2024
Profile last updated: 28 May 2024


A compact rodent, chubby-cheeked, with a short, wide face and ears, and long, dense, fine fur. It is brown above, with attractive, rufous highlights. The tail is shorter than the head and body length (Rattus species have tails as long or longer than the head and body). The tail is ringed, with very little fur. This species' large, fibrous, green droppings are distinctive. Broad-toothed Rats are more similar, genetically and ecologically, to native mice (Pseudomys species) than to Rattus species. The females' maximum number of four nipples distinguishes them from the Rattus species, which have at least twice as many. Broad-toothed Rats are gentle in demeanour and are very much an Australian native 'guinea-pig' in appearance and character.
This species is currently listed by the Commonwealth as Mastacomys fuscus mordicus — Broad-toothed Rat (mainland), Tooarrana


In NSW the Broad-toothed Rat occurs in two widely separated areas: the wet alpine and subalpine heaths and woodlands in Kosciuszko National Park, adjacent Nature Reserves (Bimberi and Scabby NR) and State Forest (Buccleuch SF) in the south of the State, and on the Barrington Tops, north-west of Newcastle. In Victoria - South Gippsland and the Otways - and western Tasmania, it can be found in wet sedge and grasslands at lower elevations.

Habitat and ecology

  • The Broad-toothed Rat lives in a complex of runways through the dense vegetation of its wet grass, sedge or heath environment, and under the snow in winter. This relatively warm under-snow space enables it to be active throughout winter.
  • A male’s home range overlaps those of several females.
  • Sheltering nests of grass are built in the understorey or under logs, where two or three young are born in summer. In winter the rats huddle together in nests, for warmth.
  • Food is mostly, gathered at night, in summer and autumn and during the afternoon and early evening in winter. The diet consists almost solely of greenery - grass and sedge stems, supplemented by seeds and moss spore cases.

Regional distribution and habitat

Click on a region below to view detailed distribution, habitat and vegetation information.


Recovery strategies

Activities to assist this species

Information sources

IBRA Bioregion IBRA Subregion Known or predicted Geographic restrictions region
Australian AlpsSnowy Mountains Known None
South Eastern HighlandsBondo Known None
South Eastern HighlandsMonaro Known None