The dusky hopping mouse (Notomys fuscus), is a small rodent endemic to Australia, inhabiting desert regions characterised by sand dunes. Populations have experienced significant declines since the arrival of Europeans, and continue to be subject to threatening processes. It is currently listed as a threatened species.
Taxonomy
The dusky hopping mouse, or Wilkinti, is a mammal in the order Rodentia, and suborder Sciurognathi. The species is in the family Muridae and the subfamily Murinae (includes all Australian native rats and mice). The dusky hopping mouse belongs to the genus Notomys, a group of desert-dwelling rodents.
The species was originally described as Ascopharynx fuscus (Wood Jones 1925) from a specimen collected in South Australia. Subsequent collections were described as Notomys fuscus eyreius in 1960. Hopping mice collected in Queensland between 1957 and 1959 were described as a new species, Notomys filmeri, however, later taxonomic investigation revealed these were Notomys fuscus.
Description
The dusky hopping mouse has pale orange-brown upper parts, occasionally with grey tinged streaks. The under parts are grey-white. It grows to 80–115 mm long, with an average weight of 35 g. The tail is between 120 and 155 mm long, ending in a tuft of dark hairs. They have a well-developed throat pouch, with an opening surrounded by a fleshy margin with inward pointing, coarse white hairs. Its ears are large and furless for dissipating heat, and they have prominent dark eyes, and strong incisor teeth. It has short front legs, and long, elongated hind feet. with only three pads on the sole. Male reproductive anatomy is distinctive. The glans is small and tapered towards the tip. The surface has large dorsally projecting spines, with slightly curved tips. The testes are extremely small compared to other native rodents. Females have two pairs of inguinal teats.
Distribution
The species historically inhabited large areas of central Australia, south-west Queensland, and far west South Australia, and Western Australia. Sub-fossil specimens were found in far-south South Australia, near the Flinders Ranges. Populations were recorded in the Northern Territory, however have not been observed since 1939. It is highly likely to have occurred in western New South Wales. Distribution has shown a marked decline of more than 90% since the arrival of Europeans, with populations now patchy and highly fragmented. It is currently thought to be restricted to the Cobblers Sandhills and Strzelecki Desert in north-east South Australia, south-west Queensland and far north-west New South Wales. The species was presumed to be extinct in New South Wales, before being re-discovered in Sturt National Park in 2003. Since then, a number of sightings have been recorded near Broken Hill, New South Wales.
Ecology
Habitat
The preferred habitat of the dusky hopping mouse is the crests and slopes of stabilised desert sand dunes and ridges, with sand required for digging burrows. Dense populations tend to occur only within the vicinity of major drainage systems. It does not appear to favour a particular vegetation type, occurring in dunes well-vegetated by canegrass (Zygochloa paradoxa), as well as degraded ecosystems dominated by ephemeral herbaceous species. It has also been associated with perennial shrub species such as nitre bush (Nitraria billardierei) and Acacia species.
Behaviour
The dusky hopping mouse is a social species, living in colonies of up to five individuals. They live in burrows consisting of vertical shafts with a series of entrances approximately 3 cm in diameter, leading to a network of horizontal tunnels and chambers extending up to 2m deep. Notomys species dig their burrows from below, resulting in an absence of loose sand surrounding the entrance holes. This species prefers to forage at night in sheltered microhabitats, rather than open areas, to avoid the risk of predation. It is an opportunistic, omnivorous feeder, however is considered a granivore (74% of the diet). Green plant material, insects, and fruits are also eaten. It does not need to drink water. The neck throat pouch is a glandular area, used for marking territories. Females may scent-mark their young, ensuring they acquire a smell that grants them acceptance within the colony.