Delicate mouse (Pseudomys delicatulus) - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Delicate Mouse Pseudomys delicatulus (Gould 1842) as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act. Listing of endangered species is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. The Delicate Mouse is a very small native rodent that ranges in weight from 6-15g. The species' fur is yellow-brown to grey-brown above and white or cream below. The Delicate Mouse is chiefly granivorous with its diet composed mainly of seed from native grasses (Braithwaite and Covacevich 2000).

2. The Delicate Mouse is distributed from the north west coast of Western Australia, across northern Australia to the south-east coast of Queensland. Until recently, no records of the species were known from NSW. In 2002, as part of intensive surveys at 160 sites in the Brigalow Belt South Bioregion, three individuals were trapped at two sites in Bebo State Forest, north of Warialda near the NSW-Queensland border (M. Pennay, pers. comm.): one in Smooth-barked Apple, (Angophora leiocarpa) woodland on deep sandy soil; and two in Broad-leaved Ironbark - Silver-leaved Ironbark ( Eucalyptus fibrosa -  E. melanophloia) woodland. These records represent a significant southern extension of range for the species.

3. The ecology of the outlying NSW population of Delicate Mouse may be inferred from observations on populations throughout the rest of its range. The Delicate Mouse has been found to occupy grassy habitats and excavates simple burrows down to 40cm in depth (Braithwaite and Covacevich 2000). Occasionally, individuals will excavate burrows in termite mounds. The species appears to tolerate open, sparsely vegetated areas that usually exclude other small mammals e.g. coastal sand-dunes. The species may also persist in areas that have been heavily grazed or trampled by cattle, however areas with friable soils that are suitable for burrowing are preferred.

4. Within populations, the abundance of Delicate Mouse may fluctuate considerably. Under favourable conditions the species is capable of breeding continuously (Braithwaite and Brady 1993).

5. The Delicate Mouse is vulnerable to extinction via stochastic events given its apparent extreme rarity and isolation in NSW. Further, the species is threatened by predation from the Feral Cat, Felis catus, and European Red Fox,  Vulpes vulpes.

6. In view of the above the Scientific Committee is of the opinion that the Delicate Mouse Pseudomys delicatulus (Gould 1842) is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Dr Lesley Hughes
Chairperson
Scientific Committee

Proposed Gazettal date: 22/07/05
Exhibition period: 22/07/05 - 16/09/05

References 

Braithwaite RW, Brady P (1993) The delicate mouse, Pseudomys delicatulus: a continuous breeder waiting for the good times.  Australian Mammalogy 16, 94-98.

Braithwaite RW, Covacevich J (2000) Delicate Mouse Pseudomys delicatulus (Gould, 1842). In 'The Mammals of Australia.' (Ed. R Strahan) pp. 575-576. (Reed Books Australia: Chatswood)