Document ID: chunk:federal_register_of_legislation:F2023L01713:body:0:p28
Version: federal_register_of_legislation:F2023L01713
Segment Type: other
Provision Reference: 
Character Range: 147674–150603

significant prey item on the extensive floodplains of the Northern Territory (Woinarski et al. 2000).
Figure 15: Abundant crabs in mangroves that are occupied by the water mouse.
Source: © Melissa Bruton (Cairns in 2022).

3.7                  Movement
Recorded minimum water mouse home range sizes on Minjerribah/North Stradbroke Island varied from 0.3‑0.9 ha, with one outlier value of 3.4 ha at a site with widely spaced mature mangrove trees and very low substrate complexity (Van Dyck 1996). Most of the time was spent in non-overlapping 0.2 ha core areas (Van Dyck 1996). Agonistic encounters between individuals have been observed (Van Dyck & Gynther 2003).
Individuals emerge from shelters and follow the receding tide through sedgelands and mangroves before retreating as the tide – or daylight – returns (Van Dyck 1996). Radio-tracked individuals spent an average of 85 % of their time outside shelters in frenetic activity (Van Dyck 1996). In addition to feeding, individuals visit neighbouring shelters and favoured haunts, as well as participating in shelter maintenance (Van Dyck 1996; Kaluza et al. 2016).
The water mouse appears to have limited ability or propensity to swim (Thomas 1889; Magnusson et al. 1976; Van Dyck 1996) despite its name and semi water-adapted morphology (Redhead & McKean 1975).
The agility of the water mouse may vary, with individuals described as having limited ability to climb mangrove trees in southeast Queensland (Van Dyck 1994, 1996) yet 'climbing agilely among the outer branches in a manner reminiscent of the pigmy [sic] possum' in Arnhem Land (Magnusson et al. 1976).
Figure 16: A water mouse moving through mangrove habitat.
Source: © Ian Gynther (west K'gari/Fraser Island in 2016).

3.8                  Connectivity and dispersal
The water mouse has low genetic diversity across its distribution, and individuals from across its range are morphologically consistent, suggesting a recent radiation and significant historical population connectivity. There is some genetic variation across the national population, which is expected given its linear coastal distribution. Currently it is unclear if discrete boundaries in genetic structure among geographic regions are due to reduced water mouse gene flow among widely dispersed sampled locations (e.g. Mackay vs. Agnes Water) or an absence of genetic samples in intervening locations (Benfer et al. 2011).
There is currently no recorded information about the capacity for the water mouse to disperse, or about coastal barriers to water mouse population connectivity. The water mouse can travel over 600 m per night between shelter and feeding grounds (Van Dyck 1996), 1 km in a few hours (Kaluza 2021 pers. comm.), and 2.9 km overnight when foraging (Van Dyck 1994), and only small amounts of migration are required to maintain the genetic resilience of water mouse populations across its distribution (Benfer et al. 2014).