336.

Australian Broad-toothed Rat

Mastacomys fuscus

French: Mastacomys sombre / German: Australische Breitzahnratte / Spanish: Rata de dientes anchos

Other common names: Broad-toothed Mastacomys, Broad-toothed Mouse, Broad-toothed Rat

Taxonomy. Mastacomys fuscus Thomas, 1882,

Tasmania, Australia.

Studies by F. Ford in 2006 and B. Breed and Ford in 2007 suggested that M. fuscus might be most closely related to Pseudomys nanus and P. gracilicaudatus . Form M. mordicus was synonymized with M. fuscus by T. Iredale and E. L. G. Troughton in 1934 and by C. H. S. Watts and H. J. Aslin in 1981, but recognized at species level by |. R. Ellerman in 1941, and as a subspecies of

fuscus by Troughton in 1967 and by most subsequent authors. M. wombeyensis, described in 1956 from fossil material, was synonymized with fuscus by N. A. Wakefield in 1972, and with mordicus by R. Strahan in 1983 and subsequent authors. Subspecies brazenor, from near Beech Forest, Victoria, was synonymized with fuscus by Watts and Aslin in 1981 and with mordicus by Strahan and subsequent authors. Two subspecies recognized.

Subspecies and Distribution.

M.f.fuscusThomas,1882—nowrestrictedtoN&WTasmania,butsubfossilevidence(owlpellets)indicatesaformerlymoreextensiverangeacrossTasmania.

M. f. mordicus Thomas, 1922 — highly fragmented in mainland SE Australia, including the Otway and Dandenong ranges, coastal areas of Gippsland and SE New South Wales, and the Great Dividing Range around Barrington Tops and from near the Brindabella Range S to Warburton.

Descriptive notes. Head-body 142-195 mm, tail 100-135 mm, ear 20-23 mm, hindfoot 31-35 mm; weight 97-180 g. The Australian Broad-toothed Rat is a distinctive mid-sized chunky rat with a hunched posture, short, broad head and fine, dense fur. Cheeks are well developed. Dorsal pelage is dark brown tinged with rufous and yellow, gradually grading to the ventral pelage through the somewhat lighter sides. Ventral pelage is a lighter buffy gray compared to dorsum, which it is not sharply demarcated from. Ears are short, rounded, dark brown, and have a tuft of long hairs in the inside behind the opening; vibrissae are relatively short. Feet are dusky brown and hindfeet are relatively long. Tail is short (¢.70% of head-body length) and uniformly dark blackish brown with short bristly hairs throughout. Skull has broad molars and incisors, with M3 as long as M1. Females have two pairs of inguinal mammae. Chromosomal complementis 2n = 48.

Habitat. Occurs in a range of vegetation types, but mostly alpine and subalpine heathlands, wet sedgelands, and areas with dense undergrowth in tall open forests, also occasionally coastal grassy or shrubby dunes; it has persisted mostly in areas with high rainfall, cool to cold winters, and moderate to dense ground cover of grasses, sedges, and shrubs. In alpine and subalpine areas, often most common adjacent to streams, steep banks, and rocks.

Food and Feeding. The Australian Broad-toothed Rat is herbivorous, and mostly consumes grasses and sedges, with some shrub foliage. It produces large quantitiesof characteristic large, green, fibrous fecal pellets.

Breeding. Breeding is seasonal, females giving birth to one or two litters (each of 1-young) per season between October and March. Gestation lasts ¢.35 days. Young are born with fur.

Activity patterns. Terrestrial and mainly nocturnal, although up to 40% ofactivity may occur diurnally. In alpine areas, during winter, the Australian Broad-toothed Ratis active (especially in afternoons and evenings) in the vegetation layer under snow cover. Individuals move around their home range in a network of runways constructed under vegetation. This species is generally more gentle in disposition when handled than cooccurring native Rattus species.

Movements, Home range and Social organization. Largely sedentary, but some individuals at least locally nomadic. Home-range size varies between seasons and sexes. In alpine areas, females have overlapping average home ranges of about 0-1 ha in autumn-winter and 0-16 ha in summer; average for males is 0-27 ha in breeding season, and these overlap home ranges ofseveral females. In winter, the rat dens communally during the day in nests of shredded grass situated in dense undergrowth or under logs beneath snow. In summer, adult individuals nest alone. In suitable habitat,it may attain relatively high densities: one subpopulation in Kosciusko National Park averaged density of 12 ind/ha over a twelve-year study period, but it is more generally scarce and declining, with notable absences now from many sites with apparently suitable habitat.

Status and Conservation. Classified as Near Threatened on The [UCN Red List; subspecies mordicus is listed as vulnerable under Australian legislation. The species has undergone a marked and ongoing contraction in distribution and presumed population reduction overthe last c.200 years, this mostlikely due to predation by the introduced European Red Fox (Vulpes vulpes) and feral house cat. Foxes selectively hunt this species. In some areas, it has also suffered habitat loss and degradation through grazing by introduced herbivores, and changed fire regimes. Global climate change is also likely to reduce the extent of preferred habitat. At the time ofEuropean settlement of Australia the Australian Broad-toothed Rat had a far more extensive and continuous distribution, including Kangaroo Island and the Fleurieu Peninsula, South Australia.

Bibliography. Adams etal. (2016), Bilney et al. (2010), Breed & Ford (2007), Bubela & Happold (1993), Bubela et al. (1991), Calaby & Wimbush (1964), Carron et al. (1990), Ellerman (1941), Ford (2006), Fusco et al. (2016), Green (2002, 2003), Green & Osborne (2003), Green et al. (2008), Happold (1989, 1998, 2011), Hocking & Driessen (2000), Iredale & Troughton (1934), Jackson & Groves (2015), O'Brien et al. (2008), Seebeck (1971), Strahan (1983), Troughton (1967), Van Dyck & Strahan (2008), Wakefield (1972), Wallis et al. (1982), Watts & Aslin (1981), Woinarski et al. (2014).