Biodiversity publications archive

Refugia for biological diversity in arid and semi-arid Australia

Biodiversity Series, Paper No. 4
S.R. Morton, J. Short and R.D. Barker, with an Appendix by G.F. Griffin and G. Pearce
Biodiversity Unit
Department of the Environment, Sport and Territories, 1995

10. Refugia in Western Australia (continued)

10.7. Reference number WA7

Refuge area: Dirk Hartog Island

Biogeographic region: Carnarvon

Type of refuge: Islands

Lat./Long. 25°45’S / 113°03’E

Quality of refuge: Highly significant (4)

Area (km²): <1,000

Chief refuge value

Habitat for ANZECC-listed and endemic birds and reptiles.

General description

Large (617 km²) island off the coast at Shark Bay. It has rugged cliffs along the west coast, large unconsolidated dunes, and sand plain with a vegetation of heath and Acacia scrub. The pastoral station occupying the Island ran an average of 6,000 sheep over the period 1968-1984 (range 2,500-12,500)4. It has five vegetation types: tall open-heath; low-closed/open heath with hummock grasses; low very open-heath; hummock grassland; and low open-shrubland1.

ANZECC-listed species

Dirk Hartog black-and-white fairy-wren Malurus leucopterus leucopterus (V).

Loggerhead Turtle Caretta caretta (E): major nesting area for this species on the Western Australian coast is on the north-eastern corner of Dirk Hartog Island (maybe 300-400 animals per annum)12.

Regional endemics

Birds: The Dirk Hartog black-and-white fairy-wren Malurus leucopterus leucopterus and southern emu-wren Stipiturus malachurus hartogi are both endemic to Dirk Hartog Island9.

Reptiles: Western spiny skink Egernia stokesii badia11. Demansia psammophis reticulata is confined to Dirk Hartog Island and Edel Land.

Plants: Plectrachne sp., Tricoryne sp., Hakea sp., Acacia sp., Daviesia sp., Spyridium divaricatum, Scholtzia sp., Trachymene elachocarpa, an unnamed subspecies of Santalum spicatum (also Bernier, Dorre and Peron), and Ptilotus alexandri (also Edel Land)8.

Spiders: Two of seven species collected are Shark Bay endemics (Badumna veliferum and Paraplectanoides cerula)7.

Relict species

Western spiny skinks Egernia stokesii badia are found under limestone slabs in low very open heath "largely along transition zone between Eucalypt-dominated south and Acacia-dominated interior"3, 5, 11.

Other significant species

None identified.

Key threats

Overgrazing by sheep and goats3, 10, 11; predation by feral cats5. House mice are present1. Some land systems are highly susceptible to wind erosion4.

Land tenure

Pastoral lease.

Key references

1. Burbidge and George (1978)

2. Schodde (1982)

3. Maryan et al. (1984)

4. Payne et al. (1987)

5. Wilson and Knowles (1988)

6. Burbidge (1989)

7. Main (1990)

8. Keighery (1990)

9. Storr (1990)

10. Short et al. (1992)

11. Cogger et al. (1993)

12. Prince (pers. comm.)