New Holland Mouse - returning to the ACT

The New Holland Mouse has been re-introduced into the ACT after its disappearance over 100 years ago. The rare species was released to the Mulligans Flat Woodland Sanctuary in October 2013.

The New Holland Mouse (Pseudomys novaehollandiae) is a small native mouse similar in size and appearance to a house mouse. However its behaviour and ecology are quite different to the house mouse; for example, it does not enter houses.

See further details, including identification features.

The New Holland Mouse was once distributed from southern Qld near Toowoomba through to western Victoria, as well as in northern Tasmania. Like many Australian native mammals, it is highly susceptible to predation by foxes and cats. It is now largely restricted to the coast of central and northern New South Wales, with one inland occurrence near Parkes (NSW).

The species is common in collections of historically-aged bones in caves in the Canberra region, and was probably a common component of local forest, woodland and heath communities. The species has probably not occurred for 130 years in pastoral landscapes like Mulligans Flat that were cleared and developed earlier in settlement, and subject to major degradation from rabbits from 1880s onwards.

The previous role of the New Holland Mouse in woodland ecosystems is unknown because modern populations in woodlands occur at such low densities they have not really been studied.

NHM at home in it's tub with radio


The New Holland Mouse is being reintroduced experimentally to Mulligans Flat Woodland Sanctuary in the ACT, which is free of introduced predators. If the population grows, it could be expected to pass through the fence to repopulate nearby areas where predators are low.  New Holland Mice do not adapt to urban environments; the species is present adjacent to Sydney suburbs but does not enter the houses.

This reintroduction will:

  • reintroduce a locally extinct species, the New Holland Mouse, into the ACT
  • examine the factors affecting the success of reintroductions, including the behavior of individual mice
  • examine the interaction of the New Holland Mouse with the Mulligans Flat environment, and with other species that have been released into the sanctuary in an attempt to reconstruct an ecosystem.

The reintroduction process was a joint project of several organisations.

  • Mice were caught from the NSW central coast under NSW licences in 2010.
  • Priam Australia Pty Ltd built up the population at their Bungendore facility in preparation for the release into Mulligans Flat Woodland Sanctuary.
  • Captive studies were conducted using special movement-tracking software and video cameras to evaluate the relative boldness of individual mice.
  • Some of them mice in captivity were introduced to soil and leaf litter from Mulligans Flat to build familiarity with sensations from their future environment.
  • Enclosures were constructed at Mulligans Flat to accommodate the first trial release of mice, with 24 mice released in Autumn 2013 to test the ability of the captive-born mice to adapt to natural wild foods and nesting material. A few mice were unable to adapt but the majority prospered and were released into the sanctuary.
  • Another 50-70 mice were released in late October 2013. 


The research (which forms part of a PhD research program) is examining factors affecting the success of mice following introduction to an environment that has not been occupied by the species for over a hundred years. Research has characterised the behaviour of individual mice in preparation for release, to see if bolder individuals fare better or worse.

The research will also help inform a conundrum faced by modern conservation. New Holland Mice have been forced into a few refugial populations in habitats that are not typical of their former distribution. Can mice sourced from the central coast of New South Wales, bred in captivity, and then released into the wild, cope with a habitat that has been highly modified from the former woodland ecosystem they were once part of? What features of the release process, or the mice themselves, will assist in a successful reintroduction?

The movements of ten mice will be followed for the first month using tiny radio-transmitters. The fox and cat-free environment of the Mulligans Flat Woodland Sanctuary should assist the mice to settle and re-establish a population (but after so long, no one can be sure whether these mice, bred in captivity from parents sourced from coastal heath, a very different environment, will succeed in the ACT’s woodlands).

The availability of suitable food, pressure from native predators like owls and snakes, and the differences between individual mice in how they react to their release will all play a part in determining the outcome.

Mulligans Flat

Mulligans Flat Woodland Sanctuary is an initiative of the ACT Government and is managed by an external board, the Mulligans Flat Board of Management.

The 5 km2 fenced area, free of foxes, cats and dogs, is within the Mulligans Flat Nature Reserve. Mulligans Flat and Goorooyarroo nature reserves had been previously established to conserve one of the largest remaining patches of critically endangered box-gum grassy woodland.

The primary goal of the Mulligans Flat Woodland Sanctuary is to restore the woodlands to pre-1750 condition, including the reintroduction of locally extinct species. Part of this is involves investigating the roles and interactions of natural components of the woodland ecosystem in order to better inform recovery management of woodlands. Mice may be inconspicuous, but they can occur in large numbers,  and may have beneficial impacts through spreading seeds and fungal spores. They are also a small prey species that could facilitate the future release of locally extinct native predators back in to the sanctuary.

See also the Canberra Nature Park and Mulligans Flat Woodlands Sanctuary for more information.

Participating organisations

  • ACT Government
  • Mulligans Flat Woodland Sanctuary Management Committee
  • Priam Australia Pty Ltd
  • University of New South Wales
  • Foundation for Australia’s Most Endangered Species
  • NSW Foundation for National Parks and Wildlife
  • NSW Office of Environment and Heritage