Boullanger Island dunnart
Sminthopsis griseoventer boullangerensis
States and territories: Western Australia.
Regions: Boullanger Island in Jurien Bay.
Habitat: Sandy substrates covered by a dense shrub layer of cushion fan-flower Scaevola crassifolia, Acanthocarpus preissii, boobialla Myoporum insulare, coastal daisybush Olearia axillaris and nitre bush Nitraria billardieri (Crowther et al. 1999).
Habit: Ground-dwelling.
Avg. body weight: 13 g (Crowther et al. 1999).
Activity pattern: Nocturnal.
Diet: Insectivorous, but also take young mice, lizards and soft fruits (Fuller & Burbidge 1987, Dickman 2008).
Breeding: Females have only one litter per year (in August), which comprises up to eight young. The young remain in the pouch for four to five weeks, after which time young are left in a leaf-lined nest just under the soil surface until first emergence in late October (Dickman 2008).
Description
The Boullanger Island dunnart has only recently been separated as a subspecies from the Western Australian mainland grey-bellied dunnart Sminthopsis griseoventer (Crowther et al. 1999). Compared to the grey-bellied dunnart, the Boullanger Island dunnart has a longer tail, is smaller in body size, has no entoconids on the second and third molars and differs genetically by having three fixed allozyme differences out of 18 examined (Crowther et al. 1999). The two subspecies otherwise appear very similar. The results from DNA analysis indicate that this subspecies may also exist on the mainland, as the DNA profile of a sample from Lesueur, near Jurien, matched that of the Boullanger Island form. Recent taxonomic research has suggested the species does not warrant differentiation from the mainland population (Start et al. 2006).
Survey methods
On the basis of previous surveys, the following survey techniques are recommended to detect the presence of the Boullanger Island dunnart in areas up to 5 hectares in size:
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daytime searches for potentially suitable habitat resources, including but not limited to habitats with a sandy substrate and an associated dense shrub layer (description of the survey technique and recommended effort is provided in Section 3.1)
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collection of predator scats, owl casts or remains, targeting predatory bird/mammal nests/dens
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pitfall trapping surveys (description of the survey technique and recommended effort is provided in Section 3.3.8).
Hair sampling device surveys are not recommended for the Boullanger Island dunnart because it is not included among those species known to be distinguishable from hair samples (see Table 2, Section 3.3.7). Should this situation change for this species, then hair sampling may provide an appropriate alternative detection technique.
Similar species in range
Along with the Boullanger Island dunnart, the EPBC Act listed dibbler and the introduced house mouse are present on Boullanger Island and have also been recorded in pitfalls (Fuller & Burbidge 1987). Consequently, investigators must be able to distinguish between these species. For surveys conducted on the mainland, a DNA sample may be required to distinguish between subspecies of S. griseoventer. This may require appropriate permission and licensing from the relevant government organisations.
References
Crowther, M.S., Dickman, C.R. and Lynam, A.J. 1999. Sminthopsis griseoventer boullangerensis (Marsupialia: Dasyuridae), a new subspecies in the S. murina complex from Boullanger Island, Western Australia. Australian Journal of Zoology 47: 215 – 243.
Dickman, C.R. 2008. Grey-bellied Dunnart Sminthopsis griseoventer. In ‘The Mammals of Australia’ (Ed. S. Van Dyck and R. Strahan) pp. 141 – 143. (Reed New Holland: Sydney).
Fuller, P.J and Burbidge, A.A. 1987. Discovery of the Dibbler, Parantechinus apicalis, on islands at Jurien Bay. Western Australian Naturalist 16: 177 – 181.
Start, A.N, Moro, D., Adams, M. and Bencini, R. 2006. Dunnarts from Boullanger Island: new evidence and reassessment of a taxonomic issue with resource implications. Australian Mammalogy 28: 51 – 58.
Bramble Cay melomys
Melomys rubicola
States and territories: Queensland.
Regions: Bramble Cay in the Great Barrier Reef.
Habitat: Herbfield and strandline vegetation.
Habit: Ground-dwelling.
Avg. body weight: 122 g (approximately) (Dennis 2008).
Activity pattern: Nocturnal.
Diet: Unknown, probably herbivorous, but may also feed on arthropods, intertidal fauna and flora, and dead seabirds, their chicks and eggs (Dennis 2008).
Breeding: Pregnant and lactating females have been recorded in July (Dennis 2008).
Description
The Bramble Cay melomys has the smallest distribution, is the most isolated and probably the most vulnerable of all Australian mammals. The species is known only from Bramble Cay in the Great Barrier Reef, which is approximately 340 metres long by 150 metres wide (Limpus et al. 1983). The species burrows amongst low-lying vegetation and forages at night among the grass and out onto the beach (Dennis 2008). Little is known about this species, other than it is closely related to the Cape York melomys Melomys capensis and the fawn-footed melomys Melomys cervinipes (Limpus et al. 1983). The main threat to the species is habitat loss through inundation or erosion of the coral cay (Dennis 2008). Its population was estimated at 94 in 1998 (Dennis & Storch 1998), and the Cay itself is only capable of supporting several hundred individuals (Limpus et al. 1983).
Survey methods
Individual Bramble Cay melomys have been observed at night with a spotlight, foraging and moving through the vegetation onto the beach (Limpus et al. 1983). No other rodents are known to inhabit the Cay but a dedicated survey should include a capture program so that a positive identification of the species can be made.
Given the extremely isolated and small size of the known distribution of the Bramble Cay melomys, it could be assumed that any impact to the Bramble Cay may affect the species. It is advised that any surveys for the species on Bramble Cay should be conducted in conjunction with relevant Queensland government authorities.
On the basis of what is known of the Bramble Cay melomys, the following survey techniques are recommended to detect the presence of the species in areas up to 5 hectares in size:
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daytime searches for potentially suitable habitat resources, considering all available habitat on Bramble Cay (description of the survey technique and recommended effort is provided in Section 3.1)
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daytime searches for signs such scats or tracks in sandy substrates (description of the survey technique and recommended effort is provided in Section 3.2)
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Elliott A trapping surveys conducted according to the technique description and recommended effort provided in Section 3.3.9, using a mixture of peanut butter, rolled oats, honey and possibly sultanas as a bait
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spotlight surveys (conducted in a manner to avoid disturbance to nesting seabirds) conducted according to the technique description and recommended effort provided in Section 3.3.3, and
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consultation with scientists and other visitors to islands across the Great Barrier Reef region to aid in the detection of the potential presence of rodents such as this species on other islands in the region.
While the Bramble Cay melomys is not known from other islands or cays in the vicinity, the possibility that it occurs elsewhere should be considered. Fauna surveys on Great Barrier Reef islands should include a small mammal trapping program using Elliott traps and spotlighting techniques. The identity of any melomys captured on these islands must be confirmed by a rodent expert.
Similar species in range
The Bramble Cay melomys is similar in appearance to the Cape York melomys and the fawn-footed melomys (Limpus et al. 1983). The main morphological difference from these two species is the Bramble Cay melomys has a much rougher tail due to raised scales along its length, larger size, large feet and relatively small ears (Dennis 2008). Due to the isolation of the species, it is unlikely to be confused with any other species in terms of its known distribution.
As there are very few specimens of the Bramble Cay melomys, hair or tissue samples should be considered for future identification and/or molecular analysis, provided that the appropriate permission and licensing has been granted by the relevant Queensland government organisation. Similarly, any melomys caught elsewhere on the Great Barrier Reef should also considered in terms of taking hair or tissue samples for confirmation of the species’ identity.
References
Dennis, A.J. 2008. Bramble Cay Melomys Melomys rubicola. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan) pp. 673-674. (Reed New Holland: Sydney).
Dennis, A.J. and Storch, D. 1998. Conservation and Taxonomic Status of the Bramble Cay Melomys, Melomys rubicola. Progress report for Endangered Species Program, Environment Australia.
Limpus C.J., Parmenter, C.J and Watts, C.H.S. 1983. Melomys rubicola, an endangered murid rodent endemic to the Great Barrier Reef of Queensland. Australian Mammalogy 6: 77-79.
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