Document ID: chunk:federal_register_of_legislation:F2023L01713:body:0:p31
Version: federal_register_of_legislation:F2023L01713
Segment Type: other
Provision Reference: 
Character Range: 155920–158691

water mouse is a cryptic species that can be challenging to survey and detect. It is unlikely to be detected by most standard survey techniques (Ball 2004; but see Woinarski et al. 2000), requiring a targeted approach. Suitable water mouse survey techniques are:
1)        Feeding sign and prey search. The water mouse leaves a distinctive feeding sign of intact crab carapaces and chewed claws (Figure 19) in a neat cumulative midden area in open or protected locations within the intertidal foraging zone, and on shelters (Van Dyck 1996; Ball et al. 2004; Ball & Mitchell 2018; Kaluza 2019).
2)        Shelter site search. See section 3.5 for shelter details. The strong, acrid odour of the water mouse can be detected emanating from active shelter entries (Van Dyck & Gynther 2003; Kaluza 2013; Ball 2021 pers. comm.) and there is usually fresh mud and binding material – peat, dry leaves, sedges, crab shells – plastered on top (Van Dyck & Durbidge 1992). Shelters aren't always detectable: the water mouse is known to occur in locations across the Northern Territory and Queensland where shelters are yet to be observed or confirmed (Magnusson et al. 1976; Dwyer et al. 1979; Woinarski et al. 2000; Ball 2004; Gynther 2011; Ball and Mitchell 2018).
3)        Camera survey. The slate-grey colour of the water mouse, and the pure white belly and lower lip, are diagnostic characters that can be discerned on white-flash camera images for a confident identification (Ball & Mitchell 2018). The tail of the water mouse is short in comparison to other rodents, which enables it to be confirmed on greyscale camera images in some locations (Ball 2021 pers. comm.).
4)        Box trap survey. Size A Elliott box traps at potential shelters and feeding stations (Van Dyck 1996; Kaluza et al. 2016; Ball & Mitchell 2018) and placed systematically throughout suitable habitat (Dwyer et al. 1979; Van Dyck 1996; Gynther 2011) have captured the water mouse.
Cameras and box traps have reliably detected water mouse when baited with pilchards, mullet, or gar (Van Dyck 1994; 1996; Ball 2004; Gynther 2011; Ball & Mitchell 2018).
Figure 17: Box trap setups for targeted water mouse detection (left) and research (right).

Source: © Ian Gynther (left @ Bribie Island; right @ Maroochy River in 2014).
Remote cameras are effective for detecting the water mouse, monitoring behaviour, and assessing presence-absence trends at large and small scales (Gillespie et al. 2015; Ball & Mitchell 2018; Kaluza 2021 pers. comm.). However, cameras are not suitable for monitoring population abundance trends for species where individuals are unable to be identified from images (Gillespie et al. 2015), as is the case for the water mouse.
Cameras may prove vital for confirming and monitoring