Species description and taxonomy
The water mouse or false water-rat Xeromys myoides Thomas 1889 is a small native rodent recorded from coastal saltmarsh including samphire shrublands, saline reed-beds and saline grasslands, mangroves and coastal freshwater wetlands. The water mouse has small eyes and small, rounded ears. The dorsal coat is slate-grey and the belly is white. It has a maximum head and body length of 126 mm and maximum weight 64 g. The water mouse is a specialised mammal and is distinguished from other species that may be encountered in similar habitat because of its overall size and appearance. The species is also known as the false water rat and yirrkoo.
Current species status
The species is listed as 'Vulnerable' under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the Queensland Nature Conservation Act 1992 (NCA) (listed as false water-rat). In the Northern Territory X.myoides is listed under the Territory Parks and Wildlife Conservation Act 2000 (TPWC Act) as 'Data Deficient'. The species is recorded on Appendix I of CITES1. Currently, the common name used is water mouse and for the purposes of this report, X. myoides will be referred to as the water mouse.
Habitat and distribution
The water mouse has been recorded in coastal saltmarsh, mangrove and adjacent freshwater wetland habitats in the Northern Territory, Queensland and New Guinea. In Queensland, the species is known from the Proserpine area south to near the Queensland/ New South Wales border. In the Northern Territory, it has been recorded from widely separated sites in Arnhem Land, the South Alligator River, Daly River and Melville Island.
Threats to species' survival
In Queensland, habitat loss, through clearing and fragmentation, and habitat degradation due to altered hydrology are the most significant threatening processes for the water mouse. In addition, site-specific impacts from introduced animals, recreational vehicles, habitat modification including by changes in soil chemistry due to disturbance of acid sulphate soils, and pesticide applications may contribute to local population extinctions. Reflecting the very different development pressures across its disjunct range, the main threats in the Northern Territory are quite different and include coastal habitat change due to saltwater intrusion, spread of exotic pasture grasses, impacts of feral animals and livestock (especially associated with intensification of pastoral activities), and possibly predation by feral cats.
The overall objective of the recovery plan is to improve the conservation status of the water mouse and its habitat through habitat protection, reducing threats to species' survival, research and increasing public participation in recovery activities.
Summary of actions
Key actions required for the recovery of the water mouse include confirming and documenting the current distribution of the species; mapping known populations and their habitat; assessing the impact of known threatening processes; developing and implementing a threat management plan to rehabilitate habitat at priority sites; engaging the community in efforts to protect existing populations by establishing voluntary agreements with relevant land owners and managers; and coordinating the recovery process.
Evaluation and review
This is the first national recovery plan for the species. The plan will be reviewed within five years from adoption as a national recovery plan. Relevant experts will review implementation actions and their effect on the recovery of the water mouse.
1 Appendix I includes those species that are most endangered among CITES listed animals and plants. They are threatened with extinction and CITES prohibits international trade in specimens of these species except where the purpose of import is not commercial.