The Brown Antechinus is endemic to eastern Australia, where it ranges from southern Queensland to southern New South Wales (Crowther and Braithwaite 2008). Sea level to around 1,500 m.

Antechinus stuartii are found in eastern and southeastern Australia, including Victoria, New South Wales, and Queensland. (Nowak, 1997; Strahan, 1983)

Biogeographic Regions: australian (Native )

There is sexual dimorphism in size. Weight ranges from 29-71 g in males and 17-36 g in females. Average weight is 35 g for males and 20 g for females. Body length ranges from 150-250 mm in males, and 139-220 mm in females (Strahan, 1983).

Antechinus stuartii have short, dense, and somewhat coarse fur. Their back and sides are a uniform grayish-brown while the underbelly is lighter colored. The overall appearance is similar to placental mice with a long pointed head, elongate, plantigrade hind feet, a pink nose, and a tail length almost as great as body length. The tail is moderately furred, eyes are dark brown, and ears are relatively large. Females lack a pouch, instead they have a variable number of exposed nipples. The number of nipples varies by habitat. Females with 6 nipples live in the wettest areas and those with 10 nipples live in the driest and highest areas. Males are 20 to 100 percent heavier than females. (Strahan, 1983; Nowak, 1997)

Range mass: 17 to 71 g.

Average basal metabolic rate: 0.189 W.

Habitat and Ecology

Systems

• Terrestrial

Antechinus stuartii prefers wet sclerophyll forest with dense ground cover and an abundance of fallen trees in which to build nests. They usually stay on the ground, but may adopt a more arboreal lifestyle in drier areas, or where they occur sympatrically with Antechinus swainsonii, which lives on the ground. Population densities range from less than one to eighteen per hectare. Outside the breeding season males and females have their own foraging ranges. The availability of habitat may be influenced by foresters that "ring" trees leaving the trunk and major branches to rot, which provides nesting sites (Cockburn and Lazenby-Cohen, 1992). (Nowak, 1997; Strahan, 1983)

Terrestrial Biomes: forest ; scrub forest ; mountains

The diet of Antechinus stuartii consists primarily of invertebrates, particularly beetles, spiders, and cockroaches. Their diet also includes smaller amounts of vertebrates, such as placental mice, as well as plant material and flower pollen (Van Tets and Whelan, 1997). A. stuartii are voracious predators and have a high metabolism. During winter they will consume as much as 60 percent of their weight in arthropods each day. They typically hunts at night but may be active during the day, especially during times when food is scarce, such as winter months. (Strahan, 1983; Nowak, 1997)

Average lifespan

Sex: male

Status: wild: 0.9 years.

Average lifespan

Sex: female

Status: wild: 3.0 years.

Maximum longevity: 5.4 years (captivity) Observations: These are very intriguing animals from a gerontological perspective. This marsupial mouse shows Big Bang reproduction: males in the wild die during mating season of sexual stress marked by weight loss, regression of the sexual organs, and increased susceptibility to various diseases. Castration extends longevity (Roger Gosden 1996). Isolated captive males can live for more than one year, even though they exhibit the same features of wild animals during mating season, such as weight loss, and they become sterile afterwards (Diamond 1982). One captive specimen lived for 5.4 years (Richard Weigl 2005).

Antechinus stuartii have a single breeding season restricted to about three months, and produce one litter per year. Gestation lasts for 26-35 days and at least as many young as the number of nipples are usually born. With the absence of a pouch, young cling to the mother's underbelly and are dragged across the ground while she searches for food for about 5 weeks. Births usually occur within a period of about 2 weeks for any given population. Newborns are 4 to 5 mm in length at birth and weigh an average of 0.016 grams. They stay with the mother for about 90 days and reach sexual maturity in 9 to 10 months. The young leave the mother with the onset of winter. (Nowak, 1997; Strahan, 1983)

One of the more striking and unusual things about Antechinus is that all males die shortly after mating in their eleventh or twelfth month of life (McAllan, et al., 1997). This phenomenon occurs at the same time each year in any given population. Increased physiological stress results from aggression and competition between males for females, and heightened activity during breeding season. Increased stress levels apparently cause suppression of the immune system after which the animals die from parasites of the blood and intestine, and from liver infections. In the wild, many females die after rearing their first litter, although some do survive a second year. (Strahan, 1983; Nowak, 1997)

Average birth mass: 0.016 g.

Average gestation period: 30 days.

Average number of offspring: 7.

Average age at sexual or reproductive maturity (male)

Sex: male: 285 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 285 days.

Antechinus stuartii is generally not thought to be under any serious threat from humans or others, and is found in abundance in many areas. Some populations have been reduced, however, by predation from domestic cats (Nowak, 1997; Strahan, 1983). IUCN (1999) listed species decline as less than 10 percent and placed it in its "lower risk" and "least concern" categories.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Population

Population Trend

Major Threats

Conservation Actions

A possible correlation between Antechinus stuartii and the distribution of a pathogenic soil fungus (/Phytophthora cinnamomi/) was reported by Newell and Wilson (1993). P. cinnamomi can have devastating effects on plant communities such as the forests, woodlands, and heathlands of Australia (Newell, 1998).

A. stuartii may be important in the pollination of some Australian flowering plants (Goldingay et al., 1991).