Survey guidelines for Australia’s threatened non-flying mammals

Plains rat

Pseudomys australis

States and territories: South Australia and Northern Territory.

Regions: North-south band west of Lake Eyre.

Habitat: Gibber desert, particularly in areas of deep cracking clay 'gilgai' associated with minor drainage features and depressions of gilgai on gibber plains (Brandle et al. 1999).

Habit: Ground-dwelling.

Avg. body weight: 40 g (Brandle and Pavey 2008).

Activity pattern: Nocturnal, partly diurnal (Menkhorst & Knight 2004).

Diet: Omnivorous: seeds, stems, fungi and arthropods (Brandle & Moseby 1999).

Breeding: Breeds opportunistically after rain (Brandle & Moseby 1999).

Description

The plains rat is one of the larger Pseudomys species and is distinguished by having relatively large ears, a rounded snout and bicoloured tail (grey above and white underneath) (Pavey 2000).

It was formerly distributed across much of arid and semi-arid Australia, but is now restricted to a 600 kilometre north-south band to the west of the Lake Eyre Basin, with an outlying population at Lake Torrens (Read et al. 1999). The species mostly inhabits the cracking clay depressions and minor drainage lines on arid gibber plains and cracking clay plains (Brandle & Pavey 2008). The population size in favourable seasons is known to expand rapidly, when the species can also be found on surrounding dunes.

Plains rats occur in colonies that are usually small and difficult to locate, especially during periods of lower rainfall when populations collapse quickly (Brandle & Moseby 1999). The species constructs shallow burrows connected by runways that are occupied by up to 20 individuals when the species is not breeding and by one male and two to three females during a breeding event (Brandle & Pavey 2008). The burrows are often among the roots of perennial shrubs (Breed & Ford 2007). They may also live in cracks in drainage depressions where they make cup-shaped nests up to 50 centimetres beneath the surface (Breed & Ford 2007).

Survey methods

On the basis of previous surveys, the following survey techniques are recommended to detect the presence of the plains rat in areas up to 5 hectares in size:

• 
  daytime searches for potentially suitable habitat resources such as gilgai habitats associated with drainage features in gibber plains, but also sand dunes after rainfall (description of the survey technique and recommended effort is provided in Section 3.1)
  
• 
  daytime searches for signs, including burrows, tracks and scats (description of the survey technique and recommended effort is provided in Section 3.2)
  
• 
  collection of predator scats, owl casts or remains in predatory bird/mammal nests/dens (description of the survey technique and recommended effort is provided in Section 3.2)
  
• 
  Elliott A trapping surveys, conducted according to the technique description and recommended effort provided in Section 3.3.9, using a mixture of rolled oats, peanut butter and sultanas for bait
  
• 
  possibly pitfall trap surveys conducted according to the technique and recommended effort provided in Section 3.3.8
  
• 
  possibly a hair sampling device survey as the plains rat is included among those known to be distinguishable from hair samples (see Table 2, Section 3.3.7), and
  
• 
  consultation with local people, particularly investigating potential Indigenous knowledge of this species’ presence in an area and discussion with graziers and farm hands, particularly in dry periods when densities are likely to be low.
  

The survey methods recommended are comparable with those recommended by the Northern Territory DIPE (2005) and Owens (2000) for the detection of many arid species. If possible, surveys to determine the species’ presence should be conducted after rain when the population density and distribution is highest, in order to maximise the probability of locating this species.

Similar species in range

A number of other rodents overlap in distribution with the plains rat, including the desert mouse Pseudomys desertor, the house mouse Mus musculus, and the dusky hopping mouse Notomys alexis. The plains rat can be distinguished by its relatively large size, stocky build and long ears compared to other rodent species.

References

Brandle R. and Moseby K. E. 1999. Comparative ecology of two populations of Pseudomys australis in northern South Australia. Wildlife Research 26: 541-564.
Brandle R., Moseby, K.E. and Adams. M. 1999. The distribution, habitat requirements and conservation status of the plains rat, Pseudomys australis (Rodentia: Muridae). Wildlife Research 26: 463-477.
Brandle, R. and Pavey, C.R. 2008. Plains Mouse Pseudomys australis. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan). pp. 616-618. (Reed New Holland: Sydney).
Breed, B. And Ford, F. 2007. Native Mice and Rats. CSIRO Publishing, Victoria.
Menkhorst, P. and Knight, F. 2004. A Field Guide to the Mammals of Australia. (Oxford University Press: Melbourne).
NT DIPE. 2005. Guidelines for the Biodiversity Component of Environmental Impact Assessment. Prepared by the Biodiversity Conservation Division, for the NT Department of Infrastructure Planning & Environment (DIPE), NT
Pavey, C. 2000. Threatened species of the Northern Plains Rat Pseudomys australis (Notoryctes typhlops). Available from: www.nt.gov.au/nreta/wildlife/animals/threatened/pdf/mammals/plains_rat_en.pdf. Accessed 2009-03-24T10:49:35
Read. J., P. Copley, and P. Bird 1999. The distribution, ecology and current status of Pseudomys desertor in South Australia. Wildlife Research 26: 453-462.