723.

Australian Long-haired Rat

Rattus villosissimus

French: Rat a poil long / German: Langhaarige Australische Ratte / Spanish: Rata de pelo largo de Australia

Other common names: Long-haired Rat, Plague Rat

Taxonomy. Mus villosissimus Waite, 1898,

“Central Australia.”

Identified by J. A. Mahoney and B. J. Richardson in 1988 as “probably the vicinity of Goonhag-hooheeny Billabong, Cooper Creek,” Queensland, Australia.

Rattus villosissimus is in the R. sordidus species group, which clusters with the other Australian species groups. All Australian species of Rattus are sister to a cladecontaining the New Guinea endemic species, although not all species have been sampled and more research is needed to fully resolve relationships within this clade of Rattus . Monotypic.

Distribution. N &C Australia in two central core areas (Barkly Lake system of the Barkly Tableland, Northern Territory, and Channel Country in SW Queensland and NE South Australia), and Southwest I, Sir Edward Pellew Group.

Descriptive notes. Head-body 130-225 mm,tail 120-180 mm, ear 16-22 mm, hindfoot 30-40 mm; weight 60-280 g. The Australian Long-haired Rat is mediumto large-sized and similar to the Canefield Rat ( R. sordidus)and the Australian Dusky Rat (R. collettr), but it is lighter gray, with longer pelage. Body and organ weights vary seasonally, being heavier in wet season and lighter in dry season. Pelage is long and shaggy, with long black guard hairs. Dorsum is light buff to rufous, heavily grizzled with dark gray and extending onto base of tail. Some individuals have white flash on forehead. Venter is cream or pale gray. Top offeet are same color as dorsum, becoming lighter and browner on digits. Ears are blackish brown; vibrissae are fairly short. Tail is ¢.89% of head-body length, dark blackish brown, and covered in short hair. There are six pairs of mammae: three axillary and three inguinal. Diploid number is 2n = 50 (the largest for the genus), FN = 60.

Habitat. Highly restricted to refuges in arid landscape where food and water are always available. About every 20 years, populations of Australian Long-haired Rats explode into a “plague” of rats. They spread throughout a much larger area than their typical refuges because these areas are saturated with water at that time.

Food and Feeding. The Australian Long-haired Rat is mainly herbivorous but somewhat omnivorous. During population explosions, they can consume all available food resources and end up starving themselves.

Breeding. Australian Long-haired Rats reproduce year-round, and they have very high reproductive potential, similar to the Australian Dusky Rat and the Canefield Rat.

Activity patterns. Australian Long-haired Rats are normally nocturnal, moving andforaging at night and resting in burrows during the day. During plague years, starvation causes individuals to forage during the day. Temporal activity is regulated by moonlight, and on brighter nights, individuals stay in their burrows longer than normal. A study in a sand dune habitat found that during activity, individuals stayed near burrows or on sides of dunes. Itis terrestrial and nests in burrows. Nests are built on the ground, generally with multiple entrances and a central nest cavity filled with shredded grass.

Movements, Home range and Social organization. Australian Long-haired Rats are highly gregarious, and multiple individuals use in a single burrow system. Populations are extremely variable and can go from being extremely rare to being a plague ofrats during times withlots of rain and plant growth. During the rat’s plagues, distribution of the species across northern and central Australia expands into areas other than refugia that sustain their normal populations. After the population has boomed, predation, starvation, dehydration, cannibalism, and disease generally cause a massive die off. Various predators of the Australian Long-haired Rat increase in numbers during plague years. During normal, non-plague years, they will regularly immigrate between burrow systems and can move between them in association with food availability. Aggressive behavior is extremely common, and many sounds are associated with it. Five major sounds are used for communication: squeals, squeaks, tooth chattering, hissing, and coughing. Aggressive behavior seems to be when most of these sounds are used, especially the more threatening sounds like hissing and tooth chattering and a single ultrasonic sound at 64 kHz.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Australian Long-haired Rat is widespread and common;it is found in some protected areas. Destruction ofits refuge habitats due to cattle grazing might be a threat, although it has actually benefited from some human activity, especially irrigation that can act as an artificial refugia. Plagues of Australian L.ong-haired Rats caused by seasonal rains can make them a major pest because they will inevitably consume many resources and enter buildings and camps seeking food. Plagues have occurred in 1860-1861, 1869-1870, 1887, 1916-1918, 1930-1932, 1940-1942, 1948, 1950-1952, 1956, 1966-1969, 1972, and variously to the present when conditions are favorable for extreme increases in populations.

Bibliography. Begg (1975, 1976), Begg & Nelson (1977), Breed (1978), Carstairs (1974, 1976, 1980), Greenville et al. (2013), Mahoney & Richardson (1988), Menkhorst & Knight (2010), Murray et al. (1999), Musser & Carleton (2005), Predavec & Dickman (1994), Rowe etal. (2011), Van Dyck & Strahan (2008), Woinarski & Aplin (2016), Yosida (1979).