Xeromys myoides
States and territories: Queensland and Northern Territory.
Regions: Patchily distributed in coastal regions.
Queensland: between Cooloola National Park and Proserpine, including Fraser, Bribie and Stradbroke Islands (Gynther & Janetzki 2008).
Northern Territory: coastal areas west of the Gulf of Carpentaria, including Melville Island (Gynther & Janetzki 2008).
Habitat: Mangrove swamps, saltmarsh communities, freshwater swamps and lakes close to fore dunes (Gynther & Janetzki 2008).
Habit: Semi-aquatic and ground-dwelling.
Avg. body weight: 41 g (Gynther & Janetzki 2008).
Activity pattern: Nocturnal/crepuscular.
Diet: Carnivorous: marine and freshwater invertebrates.
Breeding: Breeds at any time of year, with individuals of all age classes found in communal nest mounds, but the breeding structure is unknown (Van Dyck 1997).
Little is known of the ecology or biology of the water mouse, which has been recorded in mangrove or coastal floodplain habitats in the Northern Territory, Papua New Guinea and Queensland (Van Dyck 1994). The abundance of marine invertebrate prey, particularly crabs (Van Dyck 1994) probably influences the species’ presence more than just the physical or vegetation community (Woinarski et al 2000).
Initially the species was detected when its large and elaborate mud nests were observed in the Northern Territory (Magnussen et al. 1976), but the species does not always construct such nests, sometimes using simple burrows made into the banks of the high tide mark instead (Van Dyck 1997). The presence of small middens (from the remains of their feeding) at the base of hollow mangroves has been observed at locations where the species has been detected (Van Dyck 1994).
Survey methods
The following survey techniques are recommended in the draft EPBC Act policy statement 3.20 Significant impact guidelines for the water mouse:
Primary survey techniques
Best practice surveys for the water mouse include implementation of all primary survey techniques either with or without the use of supplementary survey techniques.
Habitat assessment, daytime searches and Elliott trapping are the three most reliable methods for detecting the presence of the water mouse. Surveyors should examine aerial photos and topographical maps before commencing a habitat assessment or trapping program. This will target and identify elevated, dry supralittoral areas within mangrove communities which may support active nest mounds.
Daytime searching
Daytime searches should include transect style searches spaced at 50–100 metre intervals, or in quadrats, and involve one to two hours spent looking for nesting structures for every one hectare of intertidal or supralittoral water mouse habitat.
Elliott trapping
Elliott trapping (Size A) must be carried out at night. Elliott trapping is the only reliable method for estimating water mouse population density. Elliott traps should be baited with pilchards cut in half, mullet pieces or commercial cat food. The minimum survey effort required to trap the water mouse is 400 trap nights per four to five hectares of potential water mouse habitat.
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.
Similar species in range
This species can readily be separated from the sympatric water rat by its much smaller size, lack of a partially webbed hindfeet, and lack of the distinctive white-tipped tail. It can be separated from the sympatric black rat by the tail (not significantly longer than the head and body length), its short ears, sleek grey dorsal fur and white belly fur (Menkhorst & Knight 2004).
References
Ball, D. 2004. Distribution and habitat of the false water rat, Xeromys myoides Thomas 1889 (Rodentia: Muridae) in intertidal areas of central eastern Queensland. Memoirs of the Queensland Museum, 49(2): 487-49.
Gynther, I.C. and Janetzki, H. 2008. Water Mouse Xeromys myoides. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan) pp. 664-666. (Reed New Holland: Australia).
Magnussen, W.E, Webb, G.J.W. and Taylor, J.A. 1976. Two new locality records, a new habitat and a nest description for Xeromys myoides Thomas (Rodentia: Muridae). Australian Wildlife Research 3: 153-157.
Menkhorst, P. and Knight, F. 2004. A Field Guide to the Mammals of Australia. (Oxford University Press: Melbourne).
Van Dyck, S. 1994. The rats at Neptune’s Table. Australian Natural History 24(8): 30-37.
Van Dyck S. 1997. Xeromys myoides Thomas (Rodentia: Muridae) in mangrove communities of North Stradbroke Island, southeast Queensland. Memoirs of the Queensland Museum 42: 337-366.
Woinarski J.C.Z., Brennan, K. Dee, A., Njudumul, J., Guthayguthay, P. and Horner, P. 2000. Further records of the False Water Rat Xeromys myoides from Coastal Northern Territory. Australian Mammalogy 21: 221-223.
Western barred bandicoot (Shark Bay)
Perameles bougainville bougainville
States and territories: Western Australia.
Regions: Bernier and Dorre Island, Shark Bay.
Habitat: Dense scrubby vegetation behind dunes.
Habit: Ground-dwelling; nests in shallow scapes under prostrate shrubs (Friend & Burbidge 1995).
Avg. body weight: 226 g (Friend & Burbidge 1995).
Activity pattern: Nocturnal.
Diet: Omnivore: insects, seeds, roots, tubers herbs and small vertebrates (Friend 2008).
Breeding: Births recorded from April to October, with between one to three young born per litter (Friend 2008).
Description
The western barred bandicoot from Shark Bay is one of several bandicoot subspecies described from mainland and island specimens collected in the 1800s (Friend 2008). The species has become extinct on the mainland but P. b. bougainville persists on Dorre and Bernier Islands in Shark Bay, Western Australia (Friend 2008). The small size of the Islands (Dorre Island 53 square kilometres and Bernier Island 44 square kilometres) restricts the area available to the western barred bandicoot population. The population is relatively small (2200–4400 combined), and fluctuates with rainfall, but the species remains abundant within its restricted range (Short et al. 1998).
The western barred bandicoot is nocturnal, sheltering during the day in a concealed nest made from plant material in a hollow scrape beneath low shrub or other suitable cover (Short et al. 1998). The bandicoots emerge at dusk to forage for insects and dig for roots and other plant material (Friend 2008). Male home ranges are larger than those of females (2.5–14.2 hectares relative to 1.4–6.2 hectares), but the home range of both sexes decreases with an increase in population density (Short et al. 1998).
Introduced predators, changed fire regimes and the expansion of arid zone grazing are implicated in the demise of the mainland populations of the western barred bandicoot (Richards & Short 1997). As part of the recovery program for this species, a small population (originating from the Shark Bay Islands) has recently been re-introduced into a predator-free controlled site at Heirisson Prong, mainland Shark Bay (Richards & Short 1997). One of the purposes of the reintroduction program is to mitigate against the possibility of catastrophic events (such as an outbreak of disease, the introduction of a predator or fire) destroying the island populations.
Survey methods
On the basis of previous surveys, the following survey techniques are recommended to detect the presence of the western barred bandicoot in areas up to 5 hectares in size:
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daytime searches for potentially suitable habitat resources, such as a densely vegetated understorey habitat (description of the survey technique and recommended effort is outlined in Section 3.1)
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daytime searches for signs of activity, including tracks, scats, nests and conical foraging holes (description of the survey technique and recommended effort is outlined in Section 3.2)
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collection of predator scats, owl casts or remains, targeting predatory bird/mammal nests/dens (description of the survey technique and recommended effort is outlined in Section 3.2)
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soil plot surveys conducted according to the description of the technique and the recommended effort provided in Section 3.3.2
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spotlight surveys conducted according to the description of the technique and the recommended effort provided in Section 3.3.3
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cage trapping surveys conducted according to the description of the technique and the recommended effort outlined in Section 3.3.10
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hair sampling surveys using baited hair traps should be used as this species can be identified from hair samples (B Triggs pers. comm.; Table 2), A description of the survey technique and recommended effort is outlined in Section 3.3.7
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baited camera traps using universal bait (description of the survey technique and recommended effort is outlined in section 3.3.6).
Existing methodology as used on Dorre and Bernier Islands is likely to be most effective for detecting the western barred bandicoot. Should surveys be required on the mainland, then expert advice should be sought from relevant government authorities in Western Australia. Any signs of this species on the mainland should be reported immediately to the Western Australian DEC.
Similar species in range
There are no similar species within the known range of the western barred bandicoot.
References
Friend, J.A. 2008. Western barred bandicoot Perameles bougainville. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan) pp. 182-184 (Reed New Holland: Sydney).
Friend, J.A. and Burbidge, A.A. 1995. Western barred bandicoot Perameles bougainville. In ‘The Mammals of Australia’ (Ed. R. Strahan) pp. 178-180 (Reed Books: Sydney).
Richards, J.D. and Short, J. 1997. Rare and endangered - western barred bandicoot. Nature Australia 25: 20-21.
Short, J., Richards, J. D. and Turner, B. 1998. Ecology of the western barred bandicoot (Perameles bougainville) (Marsupialia: Peramelidae) on Dorre and Bernier Islands, Western Australia. Wildlife Research 25:567-586.
Triggs, B. (2009). Dead Finish. Personal communication regarding the Western-barred Bandicoot.
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