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Mastacomys fuscus 

Scope: Global
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_onStatus_vu_offStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Muridae

Scientific Name: Mastacomys fuscus
Species Authority: Thomas, 1882
Common Name(s):
English Broad-toothed Rat, Broad-toothed Mouse
Synonym(s):
Pseudomys fuscus (Thomas, 1882)

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2016
Date Assessed: 2015-07-25
Assessor(s): Woinarski, J. & Burbidge, A.A.
Reviewer(s): Amori, G.
Contributor(s): Dickman, C., Menkhorst, P., Green, K., Happold, D., Driessen, M. & Milner, R.
Facilitator/Compiler(s): Kennerley, R.
Justification:
Broad-toothed Rat is assessed as Near Threatened because this species has been, and continues to be, in significant decline (but probably at a rate of less than 30% over ten years) because of habitat degradation and loss through much of its range (largely due to introduced species) and predation (mostly by introduced foxes; also feral cats), thus making the species close to qualifying for Vulnerable under criterion A. Climate change is also likely to adversely affect this species in a number of ways.

The rate of decline is difficult to evaluate, because substantial monitoring programs are in place at only one site, but this program has shown a decline of  more than 50% over the period 1999-2008 (Woinarski et al. 2014). It is possible that this rate applies to at least some other mainland subpopulations, which may make the species eligible for threatened status. Assessment will be much more confident if monitoring programs are established for Tasmanian and most mainland subpopulations.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to Australia. The Broad-toothed Rat has a highly disjunct relict distribution, with isolated subpopulations in western Tasmania, the Otway Ranges, Wilsons Promontory, Dandenong Ranges, scattered across the Great Dividing Range from near Warburton (Victoria) to the Brindabella Range (Australian Capital Territory), and around Barrington Tops (Seebeck and Menkhorst 2000, Green and Osborne 2003, Milner et al. 2015). The status in coastal areas of East Gippsland and south-eastern New South Wales is poorly known, but there have been at least two recent records from near Cann River (C. Dickman pers. comm). On the Barrington Plateau, O’Brien et al. (2008) identified 12 swamps where the species persisted, and 13 swamps for which there was a history of colonisation and local extinction.

The distribution of the Broad-toothed Rat has declined significantly since European settlement (Seebeck 1971, Menkhorst 1995, Hocking and Driessen 2000, Bilney et al. 2010), and its area of occupancy is probably continuing to decline, particularly in the mainland component of its range (Seebeck and Menkhorst 2000, Green and Osborne 2003, Green et al. 2008, IUCN 2008, Happold 2008). For example, IUCN (2008) reported that it had not been recorded in the Otway Ranges ‘for the last 30 years’; the last records from the Victorian Western District Plains and far East Gippsland are before 1900, from west Gippsland before 1950, and from Wilson’s Promontory before 1980.

It has been recorded from sea level up to 2,200 m asl (Driessen 2002, Green and Osborne 2003, Happold 2008).
Countries occurrence:
Native:
Australia (Australian Capital Territory, New South Wales, Tasmania, Victoria)
Additional data:
Estimated area of occupancy (AOO) - km2:400-40000Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:359958
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:5-50Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):2200
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

There are no robust estimates of the population size, nor that of most subpopulations. In suitable habitat, it may attain relatively high densities: the density of one subpopulation in Kosciusko National Park was 12.1 individuals/ha (range 8-19/ha) during a 12 year period (Happold 1989, 1998).  However, most sources consider it scarce and patchily distributed: Seebeck and Menkhorst (2000) noted that it was ‘generally rare and localised, but may be locally common in appropriate habitat’. Happold (2008) considered it ‘sparse to common’, and IUCN (2008) considered it ‘not a common species’.

The population size of the Broad-toothed Rat is undergoing continuing decline (IUCN 2008), although the rate and consistency across range of this decline is not well established, and the population trends in Tasmania are unknown. IUCN (2008) noted the probable recent (30 year) loss of the subpopulation in the Otway Ranges, and that there had been higher than 50% decline in the population in the Mt Kosciuszko area over the period 1999-2008, with declines also reported for most other known subpopulations (Green and Osborne 2003). K. Green (pers. comm.) noted that, in the summer of 1999-2000, the population in the Snowy Mountains fell to about 34% of average values over the previous 13 years (associated with the earliest snow thaw on record), and has not increased above that point subsequently (in part due to subsequent extensive fire, and another early snow thaw in 2006). Green and Osborne (2003) noted that ‘only subpopulations in the Snowy Mountains region, specifically those above the winter snowline (up to 1,500 m), may be considered secure in the short term’.

Woinarski et al. (2014) considered the population size was bigger than 20,000 individuals, but with low reliability given lack of assessment of abundance across most of range.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:20000-100000Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Extreme fluctuations in subpopulations:No

Habitat and Ecology [top]

Habitat and Ecology:

The Broad-toothed Rat is a terrestrial and mostly nocturnal rodent.  It is herbivorous, with grasses forming the major component of its diet; leaves of shrubs, seeds, fungi, and bark are also eaten (Carron et al. 1990).  In summer it nests in burrows in the soil. In alpine areas, in winter it dens communally during the day in nests of shredded grass situated in dense undergrowth or under logs beneath the snow (Bubela and Happold 1993). In alpine and sub-alpine areas, it is active in the vegetation layer under snow cover (Happold 1998).

Across its range, this species occupies a range of habitats, but typically is highly selective in any region. Preferred habitats include alpine and subalpine heathlands, grassland adjacent to boulder outcrops, swamps, sedgelands, coastal grassy or shrubby dunes, and sometimes forests with grassy understories (Wallis et al. 1982, Green and Osborne 2003, Milner et al. 2015). Habitat suitability is largely determined by availability of cover, proximity to watercourses and availability of grasses (Green and Osborne 2003, IUCN 2008, Milner et al. 2015). In mainland alpine areas its preferred habitats are those with rocks and shrubs (including Phebalium and Prostanthera species: D. Happold pers. comm.). In Tasmania, the species is restricted to button-grass moorland or adjacent ecotones (Hocking and Driessen 2000), or wet sedgelands and heathland (Green 2007), and in alpine areas above the impact of grazing wallabies in isolated grassland on rocky mountains (Green 2011). Because of a requirement for dense ground cover, fire reduces the suitability of this habitat, and ‘regrowth takes some years to mature to a stage suitable for re-colonisation’ (Green 2007).

 In part, the preferred habitat is naturally discontinuous, prompting a fragmented distribution for this species. However, many areas of apparently suitable habitat are unoccupied (Green and Osborne 2003, Milner et al. 2015) and the species may have limited ability to disperse across unfavourable habitat, although where discrete habitat patches are relatively close together, there may be sufficient dispersal to treat these fragmented occurrences as a meta-population (O’Brien et al. 2008).

Home range size and social dispersion vary seasonally, from about 0.1-0.3 ha. Breeding is seasonal, with females giving birth to one or two litters (of one to four young) per season between October and March (Happold 1998, Green 2007). Sexual maturity is reached in 6-12 months (Happold 2008, 2011); longevity is probably 2-3 years (Happold 2011), so generation length is here assumed to be 1-2 years. Gestation period is about five weeks (Happold 2008).

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):1-2
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: Mastacomys fuscus is not utilized.

Threats [top]

Major Threat(s): The species is threatened by predation from introduced foxes (Vulpes vulpes) (Bubela and Happold 1993, Green 2002) and Domestic Cats (Felis catus) (L. Broome pers. comm., Milner et al. 2015). Bushfires are also a threat as well as habitat destruction and modification by feral horses, rabbits, hares, pigs, and ski resort developments in some parts of its range (L. Broome pers. comm.). Introduced weeds (e.g., broom (Cytisus species) and an exotic grass (Holcus lanatus)) are invading habitat at Barrington Tops and willow (Salix species) is a threat in alpine Victoria. The root rot fungus Phytophthora cinnamomi is causing dieback of heath in some areas. In Tasmania, inappropriate fire regimes are a potential threat to the species (Hocking and Driessen 2000). If established in Tasmania, foxes could be a major threat to the species there. Foxes have been shown to selectively prey on this species (Green 2002). Marginalisation of habitat due to drought and increased fire frequency and loss of protective snow cover in winter with subsequent increased predation in alpine areas is predicted to occur with global warming.

Conservation Actions [top]

Conservation Actions: This species is present in the Kosciuszko National Park, Barrington Tops National Park, Victoria's Alpine National Park, Wilsons Promontory National Park (although with no recent records) and possibly Great Otway National Park (although with no recent records), as well as several other protected areas in New South Wales and the Australian Capital Territory. In Tasmania, M. fuscus is well protected as more than half of its habitat is within the Tasmanian Wilderness World Heritage Area, which incorporates several contiguous national parks (Hocking and Driessen 2000).

Fox control programs have been carried out each winter in the Kosciuszko area since 1999 and Barrington Tops since 2001 and cat control is conducted around ski resorts. Monitoring of M. fuscus populations at Kosciuszko has occurred at one site since 1978, and another seven sites (with and without fox control) since 1999, and at Barrington Tops since 2002, and in the Australian Capital Territory since 2013. Pig and weed control is also carried out at Barrington Tops and feral horse removal and predator proof fencing is being considered. Further research is needed on the population status and range of this species, especially in Victoria and Tasmania. Other research priorities include: ecology, genetics, the ability to repopulate vacant habitat patches, impacts and control measure for feral animals, competition with Rattus species and research leading to reliable population viability, habitat, and climate change models.

Citation: Woinarski, J. & Burbidge, A.A. 2016. Mastacomys fuscus. The IUCN Red List of Threatened Species 2016: e.T18563A22429430. . Downloaded on 06 December 2016.
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