In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.
|EPBC Act Listing Status||Listed as Vulnerable|
|Recovery Plan Decision||
Recovery Plan required, included on the Commenced List (1/11/2009).
|Adopted/Made Recovery Plans||
National Recovery plan for the water mouse (false water rat) Xeromys myoides (Department of the Environment and Resource Management, 2010) [Recovery Plan].
|Other EPBC Act Plans||
Threat Abatement Plan for predation by feral cats (Department of the Environment, Water, Heritage and the Arts (DEWHA), 2008zzp) [Threat Abatement Plan].
Threat Abatement Plan for Predation by the European Red Fox (Department of the Environment, Water, Heritage and the Arts (DEWHA), 2008zzq) [Threat Abatement Plan].
|Policy Statements and Guidelines||
Survey guidelines for Australia's threatened mammals. EPBC Act survey guidelines 6.5 (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2011j) [Admin Guideline].
Draft Significant impact guidelines for the vulnerable water mouse Xeromys myoides (Department of the Environment, Water, Heritage and the Arts, 2009p) [Admin Guideline].
Federal Register of
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument].
Documents and Websites
|State Listing Status||
|Non-statutory Listing Status||
|Scientific name||Xeromys myoides |
|Species author||Thomas, 1889|
This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.
The Water Mouse is a small rodent and member of the Muridae family. The species has a maximum head and body length of 126 mm, although on average it is 100 mm long. Likewise the species has a maximum weight of 64 g with an average weight of 42 g (Woinarski et al. 2007). The Water Mouse has short, very dense and silky fur that is dark slate-grey above and pure white below. The fur is water resistant. The hindfeet are not webbed like other water rats, hence it is often referred to as a False Water Rat. Both the hands and feet are covered in fine white hair and the hindfeet are between 2326 mm long. The tail is 85100 mm in length, very finely ringed and covered in thin hairs (Gynther & Janetzki 2008). The species has very small eyes and ears that are round and short. It has only two molars in each of the upper and lower rows. Adults are generally white spotted dorsally and very old Water Mice are grizzled all over and have a rufous wash (Gynther & Janetzki 2008).
The Water Mouse occurs in three discrete populations in coastal Australia: Northern Territory, central south Queensland and south-east Queensland. The species may occur in the Kimberley region of Western Australia due to its close proximity with populations in the Northern Territory and the location of suitable habitat (Morris 2000). Within its range, it is patchily distributed and nowhere is it particularly abundant (Gynther & Janetzki 2008).
In the Northern Territory the species has been recorded between the Glyde River in eastern Arnhem Land and the Daly River floodplain. Populations are also known from Kakadu National Park, however the record dates back to 1903 and the location is vague, being described only as South Alligator (Woinarski 2004c). The species is also known from the Tomkinson River and Melville Island (Redhead & McKean 1975).
In Queensland the Water Mouse occurs in the central south and south-east regions. In the central south the species occurs between Agnes Water and Cannonvale and Mackey. In the south-east the species occurs between Coomera River (50 km south-east of Brisbane) (a long term monitoring program was conducted here (Van Dyck et al. 2006)) and Hervey Bay. In the south-east, significant populations occur in Great Sandy Strait and Moreton Bay, the latter including Pumicestone Passage between Bribie Island and the mainland (Gynther 2011). Other populations occur on the islands of Moreton Bay including the lee of North and South Stradbroke and Cooloola (Gynther 2011). The species is found on Fraser Island and has been recorded as far inland as Beerwah (Dwyer et al. 1979). It has been recorded at Laird Point on Curtis Island (QGC 2013).
The Water Mouse is also known to occur outside of Australia from the middle of the Torassi (Bensbach) River in south west Papua New Guinea (Hitchcock 1998).
The population size of water mouse in Queensland has been estimated at between 1001 to 10000 individuals occupying an area of between 101 to 1000 km2 (Dickman et al. 2000). No abundance estimates have been made for the Northern Territory population as few records exist and there has been relatively little survey of the species' mangrove and adjacent sedgeland-grassland habitats (Woinarski 2000).
Although the Water Mouse had been documented in three distinct locations (Northern Territory, central south Queensland, south-east Queensland) they require similiar habitat including mangroves and the associated saltmarsh, sedgelands, clay pans, heathlands and freshwater wetlands. The main habitat difference at each location is the littoral, supralittoral and terrestrial vegetation which differs in structure and composition. These differences dictate the species' nesting behaviour.
Northern Territory habitat
The species' habitat in the Nothern Territory is not as well documented as that of Queensland due to a low number of records of the species. The Water Mouse appears to utilise both intertidal and freshwater habitats. Most records have been from mangrove forests, saltmarsh, sedgelands, clay pans and freshwater melaleuca wetlands (Magnusson et al. 1976; Redhead and McKean 1975; Woinarski et al. 2000). Capture records along the Daly River were from moist regions at the edges of freshwater lagoons which had receded during the dry season from an outer margin of Paperbark, Melaleuca nervosa, and freshwater mangrove, Barringtonia acutangula. The dry season had left an exposed plain of dry cracked earth covered in grasses and sedges (Redhead & McKean 1975).
A specimen recorded from mangroves along the Tomkinson River in Arnhem Land was captured beneath corrugated iron 3 m from the rivers edge in a small patch of saltmarsh, Sporobolus virginicus, grassland surrounded on three sides by mangrove forest comprised of Avicennia eucalyptifolia, Lumnitzera racemosa, Exoecaria agallocha and Ceriops tagal var. australis (Magnusson et al. 1976). On Melville Island from the banks of Andranangoo Creek, they were found nesting within a mound of black friable mud within a tall Bruguiera parviflora mangrove forest with a few Ceriops tagal (Magnusson et al. 1976).
Habitat information from more recent captures in the Northern Territory on the floodplain of the Glyde River (Woinarski et al. 2000) included an extensively inundated saline light clay plain, with scattered low chenier ridges and patches of low chenopod shrubland intergrading with the saline grassland. This grassland was sparsely vegetated with Sporobolus virginicus, Cyperus scariosus and Cressa cretica and lacked any water in the immediate vicinity.
Central south Queensland
In central south Queensland, the Water Mouse has only been captured in the high inter-tidal zone in tall, closed fringing mangrove forest containing only Ceriops tagal and/or Bruguiera sp (Ball 2004). Although not considered core habitat, the Water Mouse has also been captured in saline grassland adjacent to a closed forest of Ceriops tagal and Bruguiera sp and in closed forest of Avicennia marina. A supralittoral bank is usually absent in this subregion (Ball 2004). Although these observations are relevant to the Cape Palmerston-Cannonvale areas (Ball 2004), habitat used in the central Queensland area may be more diverse and include habitat types similar to what is used in south-east Queensland (Ball pers. comm. cited in QGC 2013).
The type specimen from near Mackay was caught in a permanent reed swamp, covered with tall grass, shrubs and Pandanus, one mile from a beach near Mackay (Troughton 1943). The moist wallum, heath, sedgeland and freshwater influences along mangrove ecotones as described by Van Dyck (1996) were not present to any large degree at the capture sites in south central Queensland and more typically comprised distinct ecotones between mangroves and dry sclerophyll woodlands and/or saltpan (Ball 2004).
In south-east Queensland, Water Mouse habitat includes mangrove communities and adjacent sedgelands, grasslands and freshwater wetlands. Mangrove communities in this region are typically comprised of Avicenna marina var. australasica, Rhizophora stylosa, Bruguiera gymnorrhiza, Aegiceras corniculatum and Ceriops tagal var. australis (Van Dyck & Durbidge 1992; Van Dyck 1996; Van Dyck & Gynther 2003).
In south-east Queensland the upper tidal areas on the shoreward side of the mangrove zone often support sedgelands or salt meadows, comprised of Juncus kraussii, Baumea juncea, B. rubiginosa, Fimbristylis ferruginea and Sporobolus virginicus. The adjacent terrestrial communities are typically freshwater wetland, coastal woodland or wet heathland dominated variously by species such as Melaleuca quinquenervia, Corymbia intermedia, Casuarina glauca, Eucalyptus robusta, Leptospermum liversidgei, Gahnia sieberiana and Caustis blakei. A supralittoral bank may also be present and be utilised by the Water Mouse for nesting (Van Dyck & Durbidge 1992; Van Dyck 1996; Van Dyck & Gynther 2003).
Studies on North Stradbroke Island suggested that the most productive zone for the Water Mouse lies between nests at the supralittoral bank and the first 100 m into the mangroves (Van Dyck 1996). The floor of mangrove habitats provide a variety of microhabitat features important to the Water Mouse including tidal pools, channels, crab holes, pneumatophores, crevices in bark and around roots, hollows in standing and fallen timber, suspended drifts of twigs and leaves and driftwood. These microhabitats vary according to the structure of the community (Van Dyck 1996).
The Water Mouse has also been captured from a variety of freshwater wetland and wet heath habitats in south-east Queensland. The Water Mouse was captured in a dry creek-bed of the Beerwah scientific area which comprised dense Persoonia, Banksia robur, Gahnia and grass inside a five-year old slash pine plantation, 25 m from a stream fringed with Casuarina and Callitris, and 30 m from a sedge swamp fringed by Melaleuca (Dwyer et al. 1979). In Cooloola, south-east Queensland, the Water Mouse was captured in dense restiad swamp with some Gahnia and shallow surface water, within 300 m of Noosa River (Dwyer et al. 1979). On Fraser Island, the Water Mouse was recorded near Garry's Anchorage in an ecotone of reedy (Lepironia articulata) swampland and wet heathland (DEWHA 2009p).
The Queensland Department of Environment and Resource Management maps 'Essential Habitat' for endangered, vulnerable, rare or near threatened species in Queensland. This mapping is based on the buffering of known Water Mouse records. Essential habitat for the Water Mouse is currently only mapped for the Central Queensland Coast bioregion however there are plans to extend this into the Brigalow Belt and south-east Queensland bioregions in the near future (DEWHA 2009p).
The Water Mouse may nest or forage in the following Queensland Regional Ecosystems: 8.1.1, 11.1.1, 11.1.2, 11.1.4, 12.1.1, 12.1.2, 12.1.3, 12.2.5, 12.2.7, 12.2.11, 12.2.12 and 12.2.14. Regional Ecosystems that are or likely to be essential habitat for the Water Mouse are listed in the table below:
|Bioregion (Sattler and Williams 1999)||Description (EPA 2007)||Essential Habitat|
|Central Queensland Coast||Mangrove vegetation of marine clay plains and estuaries.||Yes|
|Brigalow Belt||Sporobolus virginicus grassland on marine clay plains.||Likely|
|Brigalow Belt||Samphire forbland or bare mud-flats on Quaternary estuarine deposits.||Likely|
|Brigalow Belt||Mangrove low forest on Quaternary estuarine deposits.||Likely|
|Southeast Queensland||Mangrove shrubland to low closed forest on marine clay plains and estuaries.||Likely|
The Water Mouse creates nests which are important for breeding and refuge from high tide and predators. The Water Mouse constructs five types of nests: free-standing, termitarium-like mound nests or mounds at the base of mangrove trees (e.g. Avicennia marina), mound nests on small elevated 'islands' within the tidal zone, mound nests or holes in supralittoral banks; nests inside hollow tree trunks, and nests in spoil heaps created as a result of human activity (Van Dyck & Gynther 2003; Van Dyck et al. 2003).
Nest mounds are usually 20 to 60 cm in height with a basal circumference of 1.6 to 4.8 m, with one to three entrance holes, although other entrances may be hidden (Magnusson et al. 1976; Van Dyck & Durbidge 1992; Van Dyck & Gynther 2003). Burrow entrances can be at the top, sides or bottom, or in adjoining banks or fallen timber (Van Dyck & Gynther 2003).
Fresh mud plastering on the top of nest mounds can indicate that a mound has been built up to maintain its height above high tide level (Van Dyck & Gynther 2003). Mud pathways also may be present on the side of mounds where the Water Mouse has excavated mud from a tunnel and spread it along a track. These mud plastering's may include bits of vegetation, dried leaves, sedges and crab shells (Van Dyck & Gynther 2003). The nests recorded in sites adapted from spoil heaps include materials such as excavated or bulldozed sand, rocks and earth, and tree-stump waste (Van Dyck & Gynther 2003). A distinctive odour may indicate whether the Water Mouse is nesting in a mound (Van Dyck & Gynther 2003).
Nesting in central south Queensland does not appear to include free standing nests ascribed to the species elsewhere but seem restricted to mud ramps constructed between the buttress roots of Ceriops tagal or more commonly Bruguiera parviflora or B. gymnorrhiza (Ball 2004). Magnusson and colleagues (1976) however discovered similar free standing nests to that in south-east Queensland on Melville Island in the Northern Territory. The nest was described as a mound of black friable mud, 60 cm in height and semi circular at the base, against and interlocked within the buttress trunk of a B. parviflora.
It is assumed the Water Mouse does not need to build mounds or obvious nest structures in non-tidal environments.
Little is known about the reproductive biology of the Water Mouse however the benchmark research undertaken by Van Dyck (1996) on North Stradbroke Island has given some insight into the reproductive biology of the species in south-east Queensland. It was found that up to eight individuals of both sexes can share a nest mound, however there is generally only one sexually active male present. The nest may also be used by successive generations over a number of years. Scrotal males were recorded in all months except January, February and April.
Females in this population were presumed to be pregnant if they showed a swollen appearance and increased weights, and such females were recorded in the months of January, May, August, September and October, and females with enlarged nipples were recorded from July through to December. Juveniles were recorded in the months of May, July, August and November. Endoscopic examination of a nesting chamber on North Stradbroke Island revealed a litter of four dark-skinned but hairless young which the adult, upon detection of the endoscope, removed one by one to another location in the nesting mound (Van Dyck 1996). Van Dyck (1996) commented that in the absence of further information on breeding it would appear that the Water Mouse is capable of breeding throughout the year.
The diet of the Water Mouse has been well surveyed. Van Dyck (1996) investigated the diet of the Water Mouse on North Stradbroke Island in south-east Queensland. The composition of the diet included a variety of crustaceans (Parasesarma erythrodactyla, Helice leachi and Australoplax tridentata), marine polyclads, marine pulmonates (Salinator solida, Ophicardelus quoyi and Ochidina australis) and marine bivalves (Glauconome sp.). Investigations of middens within and outside tree hollows also revealed the remains of the mud lobster Laomedia healyi and mottled shore crab Peragrapsis laevis (Van Dyck 1996). This suite of species is common on intertidal saltmarsh habitats in south-east Queensland (Breitfuss et al. 2004).
The dietary preferences in central south Queensland appear to be similar and include grapsid crabs (Ball 2004). Whilst limited information exists on the diet of the Water Mouse in the Northern Territory, the remains of a grapsid crab, Neoepisesarma mederi were discovered within and outside a mound nest on Melville Island (Magnusson et al. 1976). Plant foods to date have not been reported in the diet of the Water Mouse, however gut morphology suggests that the diet of the Water Mouse should not be totally carnivorous (Van Dyck 1996).
The Water Mouse has been observed to travel relatively large distances of up to 3 km a night (the species is believed to be totally nocturnal) while criss-crossing home ranges averaging 0.7 ha (Gynther & Janetzki 2008). Home range estimates by Van Dyck (1996) at Rainbow Channel on North Stradbroke Island, Queensland, suggested animals had an average home range of 0.64 ha. Data from animals radio tracked by Van Dyck (1996) also indicated that males had a larger home range than females (male average 0.77 ha; female 0.53 ha). Home range estimates differed greatly between sites with animals radio tracked further south at Canalpin Creek, Queensland, having a much larger home range estimate of 3.42 ha. Larger home ranges are thought to be a result of microhabitat complexity and width of the mangrove zone at a site. The species is highly territorial (Van Dyck 1996). Nothing is known about dispersal movements in this species (Van Dyck 1996) although habitat type and topography of land to migrate through and recent weather may impact capacity for dispersal.
The following survey guidelines were developed during a workshop and should be cited as: Proceedings of a workshop for significant impact guidelines for the Water Mouse, Brisbane, April 2009. These methods are primarily for undertaking presence/absence surveys. Monitoring programs should be developed with consideration of of desired outcomes and take into account habitat, topography and weather at local sites.
Primary survey techniques
Habitat assessment, daytime searches and night-time Elliott trapping are the three most reliable methods for detecting the presence of the Water Mouse. Before commencing a habitat assessment or trapping program, surveyors should examine aerial photos and topographical maps to better understand the study area for example identify elevated, dry supralittoral areas within mangrove communities which may support active nest mounds to target during habitat assessment and trapping programs.
A habitat assessment should be undertaken with the aim of recording all notable habitat features in the study area including vegetation types and species, presence of prey species and prey middens, hollow-bearing trees etc. Habitat assessments should be done in conjunction with daytime searching. Habitat descriptions should include photos and GPS reference. Habitat assessment in conjunction with daytime searching should consider the following corroborative, but not conclusive, evidence of Water Mouse presence:
- Predator scats, owl casts or remains in nests and dens of predatory mammals and birds can help identify predatory pressure indices, although the age of remains should be taken into account.
- The presence and abundance of prey species such as grapsid crabs (for example Parasesarma erythrodactyla, Neosarmatium trispinosum and Helice leachi), mud-lobsters, green sea mussels Glauconome sp., polyclad worms, pulmonate molluscs (for example Salinator solida, Ophicardelus quoyi) and sea slugs. Published data are available for south-east Queensland, but prey composition and density will vary between subregions, and are undescribed in the Northern Territory.
- Prey middens primarily comprised of grapsid crab remains. These are usually found on the floor of the littoral zone, especially in hollows at the base of mangrove trees. However, they can be confused with middens of other littoral species such as the Water Rat Hydromys chrysogaster.
- Rodent tracks, although these are not a reliable indication owing to potential confusion with other littoral rodents (for example Rattus sp. and Melomys sp.).
A habitat assessment can include opportunistic sampling for prey species using 25 cm by 25 cm quadrats allowing for vagaries of prey, for example crab burrows at base of mangrove trees as well as in more open areas. Small pitfall traps such as plastic drinking cups may be used to sample prey within these quadrats.
Daytime searches should include transect style searches spaced at 50–100 m intervals, or in quadrats and involve one to two hours looking for nesting structures for every one hectare of intertidal an/or supralittoral Water Mouse habitat. Special attention should be paid to supralittoral banks, where present. Even low supralittoral banks may support nests, although they are also used by burrowing crustaceans and Water Mouse burrow entrances can be difficult to reliably detect.
Useful features that can aid with the recognition of active mound nests include:
- Mounds usually 20–60cm in height with a basal circumference of 1.6–4.8m, with one to three entrance holes, although other entrances may be hidden. Burrow entrances can be at the top, sides or bottom, or in adjoining banks or fallen timber.
- Fresh mud plastering on the top may indicate that a mound has been built up to maintain its height above high tide level. Mud pathways also may be present on the side of mounds where the Water Mouse has excavated mud from a tunnel and spread it along a track. Mud plasterings may include bits of vegetation, dried leaves, sedges and crab shells.
- A distinctive musty odour indicating animals are present in the mound.
- Mounds overgrown with sedges or incorporated into the roots or trunk of emergent trees such as casuarinas may be active.
- Mound nests in good indication that other, cryptic nests may also be present in mangrove trees and supralittoral banks. Water Mouse nests have also been recorded in sites adapted from spoil heaps, such as excavated or bulldozed sand, rocks and earth, and tree-stump waste.
- Regional considerations should be taken into account.
- Because nest mounds usually break down quickly if unoccupied, their presence is the most reliable indicator of Water Mouse populations.
- Tree nests may also be present in the base of mangrove tree hollows in the intertidal zone.
- The supralittoral zone may be too narrow to support nest mounds or be absent altogether; supralittoral banks may also be absent.
- Searches should concentrate on nests at the base of trees with buttress roots using transects or quadrats in the littoral zone where mature mangrove trees.
- Most Water Mouse records have been from saltmarsh, sedgelands, clay pans and freshwater wetlands, although nests in mangrove trees have been recorded.
Elliot trapping (Size A) must be carried out at night and transect layout informed by information gathered from daytime searches for nesting structures. Elliott trapping is the only reliable method for estimating Water Mouse population density. Trapping can only be carried out under a permit from the relevant State/Territory authority and must consider the following.
- Place 20 Elliott A traps (medium sized, 330 mm X 100 mm X 90 mm) at 10 m intervals per transect.
- A minimum of four transects per five ha of potential Water Mouse habitat is recommended.
- Elliott traps should be placed in a line at the top edge of the supralittoral zone; and perpendicular to the supralittoral zone through the adjacent mangroves, in a zigzag or sinusoidal curve through the intertidal zone to the low-water edge of the mangroves.
- Elliot traps should be set for a minimum of four nights.
- Pay strict adherence to tide tables to prevent traps being inundated by tidal movement.
- Elliot trapping must be undertaken during night hours.
- Place traps on littoral substrate (not in trees as water mouse does not climb well), making use of existing features, for example the base of hollow bearing trees, near nest mounds.
- Place traps on a falling tide and bait with pilchards cut in half, mullet pieces or commercial cat food.
- The location of each trap should be clearly flagged with fluorescent tape for ease of recovery and to avoid animal drownings. A continuous cotton line should be used to mark the location of the trapline.
- Pay attention to storm surges, wind and wave action, and creek crossings, which may fill up sooner than flat areas of the intertidal zone.
- Release animals in the vicinity of capture, but not where the site is inundated; if the entire site is inundated release captured animals in sloping tree hollows, not vertical trunks as they have difficulty in climbing vertical trunks. The species is extremely territorial (Van Dyck 1996) and release into sites with existing individuals may result in death.
- Exercise minimal impact on the ecosystem, that is, two people should be adequate to set and recover traps.
Supplementary survey techniques
Pitfall trapping, spotlighting and hair tubing can be used to increase the probability of detecting the Water Mouse however these techniques are not required where primary techniques are implemented.
Owing to the risk of drowning, pitfall trapping should not be used in littoral zones. Pitfall trapping is however considered a useful technique on seasonally dry floodplains and freshwater wetland habitats in the Northern Territory or south east Queensland. Seasonal flooding regimes and heavy rainfall should be taken into account when setting and checking pitfall traps.
Spotlight surveys are not a useful survey technique for the Water Mouse. At best they can only determine the species' presence and there is a high probability of confusion with other rodents (for example Rattus spp. and Melomys spp.).
Hair sampling can indicate Water Mouse presence, but is superfluous where daytime searches and Elliott trapping are carried out.
The removal and degradation of habitat as a result of development actions is the principal threat to the survival of the Water Mouse. Development actions likely to impact on the Water Mouse include sand mining, urban residential development, resorts and marina development, bund walling, aquaculture projects and creation or upgrading of easements for energy distribution or infrastructure such as electricity, gas or water pipelines. Habitats used in central south Queensland are often directly adjacent to terrestrial areas that are subject to ongoing disturbance, modification and clearing, aquaculture and housing (Ball 2004) and important populations in south-east Queensland on North Stradbroke Island are continually threatened by expansion of mining activities (Van Dyck 1996). In the Northern Territory there is a paucity of information to determine what the actual key threatening processes are (Woinarski et al. 2000). Development actions such as, but not limited to, those described above have the potential to introduce threatening processes to Water Mouse habitat, or contribute to or increase the intensity and magnitude of existing threats to the Water Mouse.
Regional Ecosystem (RE) data (EPA 2007) estimates the area of Water Mouse habitat cleared in Queensland since pre-clearing times. Using regional ecosystems considered or likely to be considered essential habitat in Queensland resulted in an estimate that 31 213 ha of Water Mouse habitat had been cleared between pre-clearing times and 2005.
The table below provides specific infomation on the extent of Water Mouse habitat cleared in Queensland. This data refers only to intertidal habitats. It does not consider freshwater habitat that has been lost and is likely to be an underestimate.
|Description (EPA 2007)||Pre clearing extent (ha)||Extent remaining in 2005 (ha)||Estimate of clearing (pre clearing to 2005)
|Mangrove vegetation of marine clay plains and estuaries.||41 024||40 248||776|
|Sporobolus virginicus grassland on marine clay plains.||35 008||17 633||17 375|
|Samphire forbland or bare mud-flats on Quaternary estuarine deposits.||11 3110||104 073||9037|
|Mangrove low forest on Quaternary estuarine deposits.||85 291||84 282||1009|
|Mangrove shrubland to low closed forest on marine clay plains and estuaries.||53 499||50 483||3016|
Alteration of natural hydrology
The Draft National Recovery Plan for the Water Mouse (DERM 2009a) lists the following alterations to hydrology as threats to the Water Mouse:
- Changes in natural hydrology including increased freshwater inflows and sedimentation from storm water run-off as a result of adjacent development.
- Physical changes to saltmarsh such as runnelling or bundwall construction that modify tidal amplitude and frequency of inundation.
- Modified water levels and salinity in tidal waterways resulting from installation of flow control gates for flood mitigation.
- Drainage of coastal and terrestrial wetlands for urban and industrial developments.
The alteration of overland water flows such as the concentration of stormwater run-off from adjacent urban areas has been observed in central south Queensland (Ball 2004). Such artificial physical processes may impact on the Water Mouse indirectly. For example, increased stormwater runoff from expanding urbanisation causes changes to salinity and sediment loads which are detrimental to populations of grapsid crabs, a major food source of the Water Mouse (Ball et al. 2006).
The fragmentation of freshwater and intertidal wetland communities is considered one of the most important issues to the Water Mouse as it can reduce potential feeding resources and nesting opportunities, extend edge effects, promote weed invasion and increase pest densities or their impacts on native fauna (DERM 2009a). Fragmented populations of Water Mouse are thought to be at high risk of local extinction through fox and possibly cat predation (DERM 2009a) and habitat fragmentation probably exacerbates feral predator impacts and restricts recruitment or recolonisation from adjacent areas (Gynther & Janetzki 2008). Development actions such as residential development are the main cause of fragmentation whilst the creation of easements for power, water and gas pipelines can also result in the fragmentation of habitat. Clearing to the edges of mangrove habitat is evident in central south Queensland (Ball 2004) and is likely to have impacts on local Water Mouse populations.
Acid sulfate exposure
An estimated 2.3 million hectares of acid sulfate soils occur along 6500 km of the Queensland coastline (DERM 2009b), coinciding with known and likely Water Mouse habitat (see Figures 1-3). Without appropriate management, development activities in coastal habitats have the potential to disturb acid sulfate soils which can release sulphuric acid and often toxic quantities of iron, aluminium and heavy metals. Acid sulfate soils can have a number of negative implications for the Water Mouse relating to habitat degradation and poor plant productivity and, most significantly, can impact negatively upon crustaceans, marine pulmonates and molluscs which are important food resources.
Although there is insufficient information available to assess the impacts of possible threatening process in the Northern Territory, the most plausible threatening processes relate to broadscale habitat changes, especially the spread of weeds (Woinarski et al. 2007). Much of the lowland wetland communities in the Northern Territory likely to support the Water Mouse are being transformed by the spread of exotic plants including Mimosa pigra and exotic pasture grasses such as Para Grass and Olive Hymenachne (DERM 2009a).
Direct biological impacts on the Water Mouse include predation pressures from native and introduced fauna (DERM 2009a). Predation pressures from feral and domestic dogs, foxes and feral and domestic cats are likely to pose significant threats to populations of the Water Mouse; particularly those located close to urban environments in parts of coastal Queensland. However, these pressures have not been quantified for isolated populations (DERM 2009a). Feral pigs, foxes and both feral and domestic cats are common throughout the central Queensland coast and their impact as predators on the Water Mouse are likely to be significant (Ball 2004).
Remains of the Water Mouse have been detected in dingo scats on Fraser Island (DEWHA 2009p), although the population-level significance of predation of Water Mouse by dingoes is unknown (DERM 2009a). The remains of a Water Mouse have also been discovered in a crocodile in the Northern Territory (Magnusson et al. 1976) however the degree to which this predation occurs is unknown. Van Dyck (1996) noted the presence of the Carpet Python (Morelia spilota), the Rough Scaled Snake (Tropidechis carinatus), and Tawny Frogmouth (Podargus strigoides) in Water Mouse habitat in south-east Queensland. Although no evidence of actual predation exists, the presence of these species in this habitat and their life history suggests the Water Mouse may be a potential prey item. It is also possible that the Water Mouse represents a prey item for the Water Rat (Hydromys chrysogaster) (Van Dyck 1996).
Herbicides, pesticides and oil pollution
In south-east and central Queensland, saltmarsh and mangrove habitats occur adjacent to agriculture (for example sugar cane lands) and urban development. Herbicides and pesticides are employed for pest management, but may also persist in natural environments (Zimmerman et al. 2000), possibly impacting non-target populations and potentially affecting the Water Mouse and/or its prey and habitat (DERM 2009a). Off-shore pollution events such as oil spills (from tankers or pipelines) have the potential to negatively influence the function and health of mangrove communities. As a result, the cumulative impacts from these activities may result in secondary effects on populations of the Water Mouse and/or its primary food sources (DERM 2009a). Researchers in North Queensland have recently discovered that a common agricultural herbicide, diuron, is correlated with the severe dieback of common grey mangroves Avicennia marina (Shearer 2004). The use of insecticides for mosquito control is also a process that may directly or indirectly affect Water Mouse populations as this process has been observed to take place in south-east Queensland where a once-known population is now considered extinct (DERM 2009a).
The use of recreational vehicles in intertidal areas is considered a threat to the Water Mouse (DERM 2009a). The creation of wheel ruts has the potential to cause saltwater incursion and supralittoral dieback. Any prolonged or intensive wave action from recreational vessels (for example jet skis, motorboats) could result in the erosion of supralittoral banks or the washing away of mound nests.
The discovery of a nest mound exposed by fire on an island in the supralittoral zone in Donnybrook, south-east Queensland (Van Dyck & Gynther 2003) suggests that fire in the supralittoral zone, whether as a result of development actions, natural or recreational activities or arson events, poses a threat to the Water Mouse. The destruction or degradation of habitat by feral and hard-hoofed animals (for example pigs) has been recorded from a number of populations of the Water Mouse (DERM 2009a). Cattle grazing in the supralittoral zone may pose a threat to Water Mouse habitat through trampling and denudation of intertidal habitats, altering hydrology, removing vegetative cover protecting animals from predation and potentially allowing for acid sulfate soil incursions.
Small terrestrial mammals, including the Water Mouse, reduce their noctorinal foraging activity in response to increasing moonlight intensity (e.g. Beier 2006), and such response occurs in all natural environments including heavily forested situations. Artificial light is expected to evoke the same response, even in forests or mangroves with relatively dense canopies. Predation risk is increased and dispersl movements are also impacted in artifically lit landscapes (Beier 2006). The species is unlikely to benefit from "diffuse noctornal illumination" as reported by QGC (2013), as the referred study (Santos et al. 2009) is about waders and not rodents or the Water Mouse. The Water Mouse has small eyes resembling those of small insectivorous bats (Van Dyck 1994) and behavioural observations suggest that the species relies most heavily on olfaction (smell), not vision, for navigating within its environment, defending its home range and foraging (Van Dyck 1994, 1997).
General mitigation advice
The following measures may assist in minimising impacts on the Water Mouse. They should be used with the aim of reducing the impact of an action to below the thresholds laid out in this document. Avoidance measures should be considered the priority. The following measures may help to avoid impacts on the Water Mouse (DEWHA 2009p):
- Retain habitat known or likely to contain Water Mouse, and manage for the species.
- Maintain existing hydrology (including any appropriate flood regime, as well as water flow and quality).
- Avoid habitat fragmentation.
- Retain supralittoral and intertidal habitat corridors.
- Maintain current site conditions (for example disturbance regimes, stock grazing, etc) until impacts or benefits of disturbance are evaluated.
If impacts are unavoidable they can be minimised by (DEWHA 2009p):
- Establishing a buffer of natural vegetation of at least 30m around areas identified as containing or linking likely water mouse habitat.
- Actively monitoring Water Mouse populations and using results to update management actions.
- Capturing and reducing development-related fresh water run-off that may reduce salinity and affect water mouse habitat and prey abundance.
- Erecting fencing to exclude livestock such as cattle, horses, feral pigs, foxes, as well as domestic dogs and cats.
- Appropriately managing and treating noxious weeds for example Mimosa.
- Adopting sensitive urban water design guidelines to avoid indirect impacts from adjacent urban development.
Experimental mitigation measures
The Water Mouse has been recorded as occupying and adapting to experimentally constructed artificial nest mounds (Van Dyck et al. 2003). Their use may expand the amount of habitat available to the Water Mouse and afford some degree of protection from feral and domestic animals. However, there is not yet sufficient evidence (for example through demonstrated application, studies or surveys) of the success of these experimental techniques to consider them effective mitigation. Until such information is available and accepted, such measures should be considered experimental and undertaken only in conjunction with accepted mitigation such as those measures listed above. Applications to carry out experimental measures must be accompanied by a fully costed and funded adaptive management strategy which clearly specifies the criteria for identifying success and identifies thresholds at which management intervention will occur. Ongoing monitoring should collect data which allow the reason behind any decline to be identified and to inform any adaptive management undertaken (Van Dyck et al. 2003).
Translocation does not reduce the impact of an action below the significance threshold. Translocation of the Water Mouse is not considered to mitigate or offset the impact of an action, since any translocation, no matter how successful, cannot lessen the loss of habitat. In limited circumstances, where a very small numbers of individuals of a species are proposed for translocation and the proposal is consistent with best practice, then translocation may be considered as compensation, in addition to appropriate mitigating measures. Such translocation may be trialled as an experiment and must be undertaken in association with a fully costed and funded monitoring program and adaptive management strategy with clearly stated criteria for identifying success. Additional permits will be required to undertake salvage translocation (Van Dyck et al. 2003).
The Draft Recovery Plan for the Water Mouse (DERM 2009a) identified the following key recovery actions:
- Identify habitats supporting populations of the Water Mouse and map the current distribution
- Confirm current distribution of the Water Mouse.
- Consolidate data of all Water Mouse records and survey results.
- Produce GIS mapping and undertaken spatial analysis of Water Mouse habitat.
- Conduct surveys and ecological assessments of potential Water Mouse habitat.
- Describe key biological and ecological features of the Water Mouse and its habitat.
- Determine whether genetic variation exists across populations of the Water Mouse.
- Understand the reproductive biology of the Water Mouse.
- Monitor sentinel field populations of the Water Mouse.
- Identify and manage threats to species' survival.
- Monitor representative populations.
- Assess impact of known threats to species' survival.
- Investigate relative impact of threats to species' survival.
- Develop and implement threat management plan.
- Rehabilitate habitat to expand extant populations.
- Regenerate habitat corridors at five sites.
- Evaluate the potential for artificial nesting structures to encourage re-colonisation of suitable habitat for the Water Mouse.
- Increase public awareness of, and involvement in, Water Mouse conservation.
- Collaborate with Indigenous landowners to exchange knowledge about the Water Mouse, its environment, threats to species' survival and management.
- Investigate opportunities for protecting the habitat of extant populations through voluntary conservation agreements.
- Develop and implement management plans for populations of Water Mouse occurring on land that is subject to voluntary conservation agreements.
- Develop and implement a community awareness and education program focusing on the Water Mouse.
Relevant management documentation from the department includes:
- Threat Abatement Plan for predation by the European red fox (DEWHA 2008zzq)
- Threat Abatement Plan for predation by feral cats (DEWHA 2008zzp).
- EPBC Act policy statement 3.20: Significant impact guidelines for the vulnerable water mouse Xeromys myoides (DEWHA 2009p).
The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.
|Threat Class||Threatening Species||References|
|Climate Change and Severe Weather:Habitat Shifting and Alteration:Global warming and associated sea level changes||National Recovery plan for the water mouse (false water rat) Xeromys myoides (Department of the Environment and Resource Management, 2010) [Recovery Plan].|
|Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation||National Recovery plan for the water mouse (false water rat) Xeromys myoides (Department of the Environment and Resource Management, 2010) [Recovery Plan].|
|Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat modification, destruction and alteration due to changes in land use patterns||National Recovery plan for the water mouse (false water rat) Xeromys myoides (Department of the Environment and Resource Management, 2010) [Recovery Plan].|
|Climate Change and Severe Weather:Sea level rise:Inundation associated with climate change||Inundation study (Environmental Resources Information Network, 2007) [Database].|
|Ecosystem/Community Stresses:Indirect Ecosystem Effects:Loss and/or fragmentation of habitat and/or subpopulations|
|Energy Production and Mining:Mining and Quarrying:Habitat destruction, disturbance and/or modification due to mining activities||Xeromys myoides in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006aah) [Internet].|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation||Mimosa pigra (Mimosa, Giant Mimosa, Giant Sensitive Plant, ThornySensitive Plant, Black Mimosa, Catclaw Mimosa, Bashful Plant)|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation||Hymenachne amplexicaulis (Hymenachne, Olive Hymenachne, Water Stargrass, West Indian Grass, West Indian Marsh Grass)|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation by weeds|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation||Vulpes vulpes (Red Fox, Fox)||Xeromys myoides in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006aah) [Internet].|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation||Felis catus (Cat, House Cat, Domestic Cat)||
Xeromys myoides in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006aah) [Internet].
National Recovery plan for the water mouse (false water rat) Xeromys myoides (Department of the Environment and Resource Management, 2010) [Recovery Plan].
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation||Canis lupus familiaris (Domestic Dog)|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Grazing, tramping, competition and/or habitat degradation||Sus scrofa (Pig)|
|Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition and/or predation||Canis lupus dingo (Dingo, Warrigal, New Guinea Singing Dog)|
|Invasive and Other Problematic Species and Genes:Problematic Native Species:Predation by reptiles||Xeromys myoides in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006aah) [Internet].|
|Natural System Modifications:Dams and Water Management/Use:Activities that lead to swamp degradation|
|Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality||
Xeromys myoides in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006aah) [Internet].
National Recovery plan for the water mouse (false water rat) Xeromys myoides (Department of the Environment and Resource Management, 2010) [Recovery Plan].
|Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes including flooding|
|Natural System Modifications:Dams and Water Management/Use:Changes in hydrology including habitat drainage|
|Natural System Modifications:Dams and Water Management/Use:Changes to habitat hydrology|
|Natural System Modifications:Dams and Water Management/Use:Habitat modification due to levee construction and associated hydrology changes|
|Natural System Modifications:Dams and Water Management/Use:Salinity|
|Pollution:Agricultural Effluents:Herbicide application|
|Pollution:Agricultural Effluents:Pesticide application|
|Pollution:Household Sewage and Urban Waste Water:Changes to water quality and quantity due to urban/agricultural runoff and stormwater|
|Pollution:Industrial and Military Effluents:Habitat degradation due to industrial discharge|
|Residential and Commercial Development:Housing and Urban Areas:Habitat loss, modification and fragmentation due to urban development|
|Residential and Commercial Development:Residential and Commercial Development:Land reclamation and soil dumping due to urban and industrial development|
|Species Stresses:Species Mortality:Death of vegetation|
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Department of Environment and Resource Management (DERM) (2009a). National recovery plan for the water mouse (false water rat) Xeromys myoides. Report to Department of the Environment, Water, Heritage and the Arts, Canberra. Brisbane: Department of the Environment and Resource Management.
Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC) (2011j). Survey guidelines for Australia's threatened mammals. EPBC Act survey guidelines 6.5. [Online]. EPBC Act policy statement: Canberra, ACT: DSEWPAC. Available from: http://www.environment.gov.au/epbc/publications/threatened-mammals.html.
Department of the Environment and Resource Management (2010). National Recovery plan for the water mouse (false water rat) Xeromys myoides. [Online]. Brisbane, Queensland: Department of the Environment and Resource Management. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/xeromys-myoides.html.
Department of the Environment and Resource Management (DERM) (2009b). Acid Sulphate Soils. [Online]. www.nrw.qld.gov.au/land/ass/index.html.
Department of the Environment, Water, Heritage and the Arts (2009p). Draft Significant impact guidelines for the vulnerable water mouse Xeromys myoides. [Online]. Draft EPBC Act policy statement. Canberra: Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/epbc/publications/xeromys-myoides.html.
Department of the Environment, Water, Heritage and the Arts (DEWHA) (2008zzp). Threat Abatement Plan for predation by feral cats. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tap/cats08.html.
Department of the Environment, Water, Heritage and the Arts (DEWHA) (2008zzq). Threat Abatement Plan for Predation by the European Red Fox. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tap/foxes08.html.
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QGC (2013). Environmental Management Plan - Water Mouse (Xeromys myoides). [Online]. Queensland Curtis LNG project. Available from: http://www.qgc.com.au/media/124856/environmental_management_plan_water_mouse.pdf.
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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.
Citation: Department of the Environment (2014). Xeromys myoides in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Sun, 13 Jul 2014 10:50:25 +1000.