720.

Australian Swamp Rat

Rattus lutreola

French: Rat des marais / German: Australische Riedgrasratte / Spanish: Rata de ciénaga de Australia

Other common names: Swamp Rat, Velvet-furred Rat (Tasmania)

Taxonomy. Mus lutreola Gray, 1841,

Moscheto Island, Hunter River, New South

Wales, Australia.

Widely used species name [ lutreolus has

been changed as original specific epithet

lutreola is a noun in apposition and thus

invariable. Rattus lutreola is sister to a clade including R. sordidus, R. colletti, R. villosissimus, and R. tunneyi in the Australian Rattus clade. Subspecies lacus is probably a distinct species based on its distinctive morphology, although genetic data are needed. Three subspecies recognized.

Subspecies and Distribution.

R.l.lutreolaGray,1841—coastalW&SAustralia,includingFraser,NorthStradbroke,andKangarooIs.

R.l.lacusTate,1951—NEQueensland,Australia.

R. l. velutinus Thomas, 1882 — Tasmania and Bass Strait Is.

Descriptive notes. Head-body 120-200 mm, tail 80-145 mm, ear 15-20 mm, hindfoot 27-35 mm; weight 55-160 g. The Australian Swamp Rat is medium-sized, stocky, and robust, with long, loose, and soft pelage, being longest in more temperate and southern regions. Dorsum is dark gray to reddish brown or blackish, with hairs having translucent bases banded terminally or tipped with rust, bronze, oryellow. Venter is somewhat paler then dorsum. Feet are dark and covered with short dark hair dorsally; hindfeet are relatively short. Ears are dark gray and rounded; vibrissae are relatively short. Tail is ¢.75% of head-body length, covered in small bristly hairs, and unicolored blackish or dark brown. Skull is robust and slightly convex dorsally, with wide incisors and molars. Various species of cestodes (Choanotaeniaand Taenia), nematodes (Capillaria, Dipetalonema, Ganguleterakis, Odilia, and Ophidascaris), mites (Guntheria, Gymnolaelaps, Laelaps, Laelapsella, Listrophoroides, Mesolaelaps, Neotrombicula, and Ornithonyssus), lice (Hoplopleura and Polyplax), ticks (Ixodes),and fleas (Acanthopsylla, Bibikovana, Leptopsylla, Macropsylla, Metastivalius, Nosopsyllus, Pygiopsylla, and Stephanocircus), a fungus, and a beetle ( Myotyphlus jansoni) have been recorded from the Australian Swamp Rat. There are 4-5 pairs of mammae: two pectoral and two (velutinus) or three ( lutreola) inguinal. Chromosomal complement is 2n = 42, FN = 60.

Habitat. Alpine areas, wet sclerophyll forest, buttongrass moorland, and temperate moist forest in Tasmania and wetland habitats in Australia, from sea level to elevations of ¢.1600 m. Generally, Australian Swamp Rats are found around late succession heath, grasses, and sedges during dry season and swampy, wet areas during wetseason.

Food and Feeding. Australian Swamp Rats mainly eat grassesand sedges, especially those obstructing their pathways. In winter, they almost exclusively eat grasses and sedges, but during the rest of the year, their diet is supplemented with fleshy fruits, seeds, and arthropods. Fungi are occasionally eaten.

Breeding. Reproduction of the Australian Swamp Rat can occur year-round, but it is most common from early spring to autumn. Estrous cycles have been estimated at four, 4-7, or 5-2 days. Gestation lasts c.3 weeks, and litters have 3-5 young. Young are c.5 g at birth and become independent in 3—4 weeks old at 25-40 g. Females can reproduce multiple times in a givenbreeding season, and females born at the beginning of the season can produce a litter near the end of the season. To be reproductively successful, a female must find and defend a territory, which is positively correlated with growth of grasses and sedges from increased rainfall. Rates of reproduction increase with rainfall. Young born in spring leave their natal population in late summer and move more than 2 km to a different population, which increases variability between populations.

Activity patterns. Unlike most species of Rattus, Australian Swamp Rats are active day and night, although some studies reported only daily activity. They construct tunnels/ runways through grass, sedge, or heath vegetation by eating obstructing plants, which might protect them from predation. Activity during the day might minimize competition with other, more nocturnal species of Rattus, Pseudomys, and Antechinus (Dasyuridae) . During the day, females forage in the densest vegetation, juveniles in the least dense, and males intermediate. During the night, all sexes foraged in dense vegetation. Australian Swamp Rats are highly mobile and need large areas to maintain large populations. They are primarily terrestrial but can swim for minutes at a time before tiring. Swimming is used to get to other patches of vegetation but not as a main mode of transportation. Nests are built in burrows up to one meter deep in areas with less water: in waterlocked areas, nests are built aboveground in tussock grass.

Movements, Home range and Social organization. Densities can be up to 15 ind/ha. Home ranges must be at least 0-2 ha for both sexes to survive winter, and both sexes become territorial to secure such an area. In spring, females continue to be territorial, but males stop. Females expand their home ranges to ¢.0-5 ha in spring; males expand theirs to up to 4 ha. Female home ranges do not overlap, but male home ranges overlap with multiple adjacent female home ranges. Population fluctuates regularly, being larger with more rainfall and more sedge and grass growth. Australian Swamp Rats have good vision that is sensitive to UV light and are competitively dominant over the Australian Bush Rat ( R. fuscipes).

Status and Conservation. Classified as Least Concern on The IUCN Red List (as R. lutreolus). The Australian Swamp Rat is common, with a wide distribution and presumably large overall population;it is found in many protected areas. Coastal development has been a threat that might have caused population declines. The major threat in northern parts ofits distribution is probably habitat alteration from inappropriate burning regime, causing grasslands to be replaced by rainforest. The species is also threatened by grazing, which can destroy grass/sedge understories.

Bibliography. Braithwaite (1980), Braithwaite & Lee (1979), Breed (1978), Burnett et al. (2016), Haering & Fox (1995), Kearney et al. (2007), McEvoy et al. (2008), Meek et al. (2012), Menkhorst & Knight (2010), Monamy (1995), Musser & Carleton (2005), Norton (1987), Rowe et al. (2011), Taylor & Calaby (1988b), Van Dyck & Strahan (2008), Watts & Braithwaite (1978).