Marble-faced delma (Delma australis) - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Marble-faced Delma, Delma australis Kluge, 1974 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 Marble-faced Delma is a brown legless lizard with black variegations and reticulations on the dorsal surface of the head and neck, and vertical black bars on sides of the head and neck (Cogger 2000). Individuals reach approximately 160-180 mm in total length.

2. The Marble-faced Delma is distributed from southern Western Australia, through South Australia and the south of the Northern Territory, to north-western Victoria and western New South Wales (NSW). In NSW, the species occurs at scattered locations within two disjunct populations: in central-western NSW in the vicinity of Round Hill and Yathong Nature Reserves; and in the south-western corner of the state. This species was recorded regularly from Yathong Nature Reserve between 1867 and 1991 but recent studies have not found this lizard.

3. The Marble-faced Delma is restricted to mallee woodland (Sadlier et al. 1996), and most records of the species have been from mallee with a spinifex,  Triodia scariosa, understorey (Shea 1991). Such habitat is represented in NSW National Parks and Wildlife Service estate and the species has been recorded in Tarawi, Yathong and Round Hill Nature Reserves. However, given their relative size and isolation, these conservation areas may not ensure the species' survival in NSW.

4. Degradation and loss of Marble-faced Delma habitat occurs in association with land use. Grazing by both livestock and feral species within mallee-spinifex habitat affects the density and structure of spinifex. Cattle, goats and sheep graze spinifex seed heads, and in the process trample the clumps (Maher et al. 1995). Grazing also affects the density of adjacent shrubs and ground cover (which offer shelter for individuals moving between spinifex clumps). Disturbance through trampling by stock degrades the soil structure and facilitates weed invasion.

5. Alteration of natural fire regimes, in association with landuse, directly affects Marble-faced Delma habitat. Pastoralists utilise fire to reduce the density of spinifex and promote the growth of vegetation that is more palatable to stock (Maher et al. 1995). However, such practises may be too frequent and non-patchy, reducing the amount of habitat and affecting the ability of individuals to recolonise burnt areas (Masters 1996).

6. In view of the above the Scientific Committee is of the opinion that Delma australis Kluge, 1974 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.

Associate Professor Paul Adam 
Chairperson
Scientific Committee

Proposed Gazettal date: 12/09/03
Exhibition period: 12/09/03 - 24/10/03

References  

Cogger HG (2000) 'Reptiles and Amphibians of Australia.' 6th Edition. (Reed Books: Chatswood.)

Maher M, Norris D, Ridge T and Robinson M (1995) 'The Ledknapper Spinifex: Its People, Plants and Animals.' (Land Information Centre: Bathurst.)

Masters P (1996) The effects of fire-driven succession on reptiles in spinifex grasslands at Uluru National Park, Northern Territory. Wildlife Research 23, 39-48.

Sadlier RA, Pressey RL and Whish GL (1996) Reptiles and amphibians of particular conservation concern in the Western Division of New South Wales: distributions, habitats and conservation status. Occasional Paper 21. (NSW National Parks and Wildlife Service: Hurstville.)

Shea GM (1991) Revisionary notes on the genus Delma (Squamata: Pygopodidae) in South Australia and the Northern Territory.  Records of the South Australian Museum 25, 71-90.