Plains mouse  (Pseudomys australis)

The plains mouse is classified as Vulnerable (VU) on the IUCN Red List (1).

Known as the ‘pallyoora’ in the Western Desert language of Australia (3), the plains mouse (Pseudomys australis) is one of the largest remaining rodent species in Australia’s arid zone. The stocky plains mouse has grey to grey-brown fur on the upperparts and cream or white underparts. The bi-coloured tail follows the same colouration pattern as the body, being grey-brown on top and cream or white on the underside, although some individuals can have an entirely white tail and feet (4). The plains mouse has long ears and a rounded snout (5), and its tail is generally shorter than, or equal in length to, the head and body together (4).

Found only in Australia, the plains mouse occurs on the gibber plains of the Lake Eyre Basin in northern South Australia and southern Northern Territory (4) (6). It formerly had a much greater range, when it could also be found in Queensland, New South Wales and Western Australia (6).

The plains mouse used to exist in a wide range of habitats but is now found mainly in stony deserts (gibber plains) or flood plains, where there are low shrubs and hard clay substrate (1), although some populations have been observed in sandy habitats (4).

A sociable animal, the plains mouse lives in small colonies that dramatically increase in number after rainfall when resources, such as food and water, are more abundant. During such population eruptions individuals move into areas that are not occupied at other times (5). A nocturnal species, the plains mouse shelters during the day in shallow burrows within cracks or at the base of bushes (4). The plains mouse has a principally herbivorous diet comprising seeds, some green plant material and the occasional insect (7). It is able to survive without drinking, as it obtains all the water it requires through its food – a useful adaptation in the dry stony plains it inhabits (6).  

The plains mouse is an opportunistic breeder that typically reproduces after a period of rainfall. A nest chamber is situated within a crack, or within a warren situated at the base of a low shrub, and is lined with dried grass and other vegetation (4). The female generally gives birth to a litter of 3 or 4 young after a gestation period of 30 to 31 days. The young attach to one of the four teats and may be dragged around during lactation (4).  The young are weaned 28 days after birth (6).

The plains mouse falls prey to a number of species including the red fox (Vulpes vulpes), dingo (Canis lupus dingo), barn owl (Tyto alba), letter-winged kite (Elanus scriptus), and mulga snake (Pseudechis australis), as well as feral cats (Felis catus) (4).

Arguably the greatest threat to the plains mouse is habitat degradation by introduced sheep and cattle (1). Their trampling destroys the burrows of the plains mouse, compacts the soil and reduces the number of cracks in which the mouse can shelter, and overgrazing reduces the food available for the plains mouse (1) (4). In addition, the plains mouse is preyed on by non-native cats and foxes (4).   

Climate change also poses a threat to the future survival of the plains mouse. If temperatures increase, the plains mouse’s shallow burrows may become too hot to inhabit, and they would only be able to persist in areas where there were very deep cracks in the clay. Climate change could also result in an increase in incidences of flooding, with potential negative knock-on effects on the plains mouse (4).

Populations of the plains mouse are found in a number of protected areas, including Witjira National Park and Mac Clark Conservation Reserve (1), and the Arid Recovery Reserve, from which foxes, cats, rabbits and livestock are excluded (4).

A National Recovery plan for the plains mouse has been drafted by the Australian Government, which outlines conservation priorities for this species. These include assessing the impact of predation by introduced mammals, and adequately protecting a sufficient area of habitat, thereby ensuring that the plains mouse can expand its range as a buffer against climate change (4) (5).  

To learn about wildlife conservation in Australia see:

• Australian Conservation Foundation:
  http://www.acfonline.org.au/