Broad-toothed rat (Mastacomys fuscus) population, Barrington Tops - endangered population listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Broad-toothed Rat, Mastacomys fuscus Thomas, population at Barrington Tops in the Local Government Areas of Gloucester, Scone and Dungog as an ENDANGERED POPULATION on Part 2 of Schedule 1 of the Act. Listing of Endangered Populations is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. The Broad-toothed Rat, Mastacomys fuscus Thomas is not listed as an Endangered Species on Part 1 of Schedule 1 of the Act, and thus populations of the Broad-toothed Rat are eligible for listing as endangered populations on Part 2 of Schedule 1 of the Act.

2. In New South Wales the Broad-toothed Rat is known from five disjunct populations. The largest population is in Kosciuszko National Park. The Barrington Tops population is of significant conservation value as it is the second largest in New South Wales.

3. The Broad-toothed Rat is a small ground-dwelling mammal of about 100-140g. It is an uncommon animal, found in alpine and sub-alpine heathlands and open eucalypt woodlands in areas that are characterised by high rainfall, a cool summer, and a cool to cold winter. Today, these habitats are restricted and fossil records indicate the Broad-toothed Rat formerly had a more extensive distribution.

4. The species appears to be restricted to patches where there is a dense ground cover of grasses, sedges and shrubs. Runways are constructed under the vegetation and large well-insulated nests of grass are built under logs and the undergrowth. In winter habitats may be covered by snow, but the animals frequent the space below the shrubs and grass tussocks.

5. The diet is specialised and consists mainly of grasses with some seeds and the leaves of shrubs. Because of the low quality of its food, an individual consumes 50-70% of its body weight in fresh vegetable matter each day. Breeding is seasonal with births occurring between December and March and the species has a mean litter size of 1.9.

6. Home ranges of females are about 1600m2 in favoured habitat and they may overlap. Dispersing individuals may move across marginal areas of low vegetation cover, so they are capable of recolonising habitats when they become locally available.

7. At Barrington Tops, recent trapping, pellet searches and the examination of fox scats revealed that the Broad-toothed Rat is not as common as it was 10-15 years ago. Also, an increase in numbers of, and competition with the sympatric Swamp Rat Rattus lutreolus, appears to be restricting the habitat usage of the Broad-toothed Rat.

8. Broad-toothed Rats have small litters, low fecundity and a slow growth rate. Threats include predation by the fox and cat, the invasion of weeds into areas of suitable habitat, competition from other rodents and herbivores such as the rabbit that open up areas of otherwise protected runways in grasslands. Climate change is a long-term threat also, due to the loss of suitable habitat.

9. In view of the points 2 – 8 above, the Scientific Committee is of the opinion that the numbers of the Broad-toothed Rat, Mastacomys fuscus Thomas, population at Barrington Tops in the Local Government Areas of Gloucester, Scone and Dungog have been reduced to such a critical level, that it is in immediate danger of extinction, it is not a population of a species already listed on Schedule 1, and it is of significant conservation value. Consequently, the Committee considers that the population is eligible for listing as an Endangered Population on Part 2 of Schedule 1 of the Act.

Proposed Gazettal date: 13/07/01
Exhibition period: 13/07/01 – 17/08/01