Secrets of the noodji (native ash-grey mouse)

By Kiarrah Smith.  Despite being subject to the greatest rate of Australian mammal species extinction over recent times, native rodents are a relatively poorly studied group. The risk of rapid decline is particularly valid for species considered ‘least concern’, but for which we have very little understanding of their biology or habitat requirements.

One such species is the ash-grey mouse (Pseudomys albocinereus), which is endemic to south-west Western Australia.  It is also known as the noodji.

Several related native rodents are listed as threatened, including the Smoky Mouse (or Konoom, P. fumeus) and New Holland Mouse (or Pookila, P. novaehollandiae). Detailed understanding of ash-grey mouse ecology is required to predict how various threatening processes may impact the persistence of this enchanting species.

A native ash-grey mouse (left) and introduced house mouse (right). Some of the features that distinguish ash-grey mice from house mice include their pale pink tail and feet, plush variably light grey to fawn fur, large eyes and round overall body shape. Ash-grey mice were also noted to generally have a much calmer disposition than house mice; the latter being much more likely to bite.

Comparison of ash-grey mouse (left) and house mouse (right) foot pads.

Video of ash-grey mouse

My Honours project, undertaken through Murdoch University, investigated the habitat use and population dynamics of the ash-grey mouse in order to facilitate informed monitoring and support proactive management for this species. Trapping and tracking of ash-grey mice was undertaken in Boonanarring Nature Reserve; located near Gingin, approximately 100 km north of Perth. A great diversity of fauna was captured, including 16 ash-grey mice.

Fluro powder
The first male captured, named Mew. Radio-transmitters were attached between the shoulder blades of ash-grey mice using a combination of gel and liquid super glues before being released at their point of capture. Fluorescent powder was applied as a complementary tracking method to confirm refuge use.

Some of the unique species captured in Boonanarring Nature Reserve.

The results of this study suggest:

  • An abundance of house mice may temporarily exclude ash-grey mice from favourable habitat by inter-specific competition for resources and/or associated hyperpredation.
  • It may be unrealistic to expect a clear pyric relationship for ash-grey mice (previous studies have suggested a negative pyric relationship) given that they are a generalist species and respond to habitat characteristics rather than fire age per se.
  • Like male sandy inland mice (Pseudomys hermannsburgensis) male ash-grey mice may undertake long distance forays in search of receptive females to mate with.
  • Ash-grey mice select microhabitat with dense understorey vegetation cover (rather than leaf litter or bare ground).
  • Ash-grey mice may use both long-term primary refuges (e.g. burrow complexes) and more temporary, ready-made secondary refuges (e.g. tree hollows, logs, grasstrees and single burrows).

From top left to bottom right: Burrow entrance, log, grasstree and tree hollow used by ash-grey mice.

The enhanced understanding of ash-grey mouse ecology gained during this study lays the foundation for suitable management and monitoring strategies to be employed by environmental managers to minimise the risk of future declines of ash-grey mice. Doing so will help ensure that this species is not added to the list of native Australian rodents that have declined to extinction.

This study has been published in Australian Mammalogy and is available at: http://www.publish.csiro.au/AM/AM17061

Many thanks to the volunteers and staff at the Department of Biodiversity, Conservation and Attractions at Swan Region and Swan Coastal District for their assistance during fieldwork. This research was conducted under the approval of the Murdoch University Animal Ethics Committee (permit RW2692/14) and funded by Murdoch University, the Calver Family Scholarship and the Department of Biodiversity, Conservation and Attractions.

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