Little Sandy Desert
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Biological survey of the south-western Little Sandy Desert NATIONAL RESERVE SYSTEM PROJECT N706 FINAL REPORT – JUNE 2002 EDITED BY STEPHEN VAN LEEUWEN SCIENCE DIVISION DEPARTMENT OF CONSERVATION AND LAND MANAGEMENT Biological survey of the south-western Little Sandy Desert NATIONAL RESERVE SYSTEM PROJECT N706 FINAL REPORT – JUNE 2002 EDITED BY STEPHEN VAN LEEUWEN SCIENCE DIVISION DEPARTMENT OF CONSERVATION AND LAND MANAGEMENT Research and the collation of information presented in this report was undertaken with funding provided by the Biodiversity Group of Environment Australia. The project was undertaken for the National Reserves System Program (Project N706). The views and opinions expressed in this report are those of the author and do not reflect those of the Commonwealth Government, the Minister for the Environment and Heritage or the Director of National Parks. The report may be cited as Biological survey of the south-western Little Sandy Desert.. Copies of this report may be borrowed from the library: Parks Australia Environment Australia GPO Box 787 CANBERRA ACT 2601 AUSTRALIA or Dr Stephen van Leeuwen Science and Information Division Conservation and Land Management PO Box 835 KARRATHA WA 6714 AUSTRALIA Biological Survey of the south-western Little Sandy Desert NRS Project N706 Final Report – June 2002 TABLE OF CONTENTS TABLE OF CONTENTS .......................................................................................................................................... iii EXECUTIVE SUMMARY ........................................................................................................................................ 1 CHAPTER 1................................................................................................................................................................ 2 THE LITTLE SANDY DESERT S.J. van Leeuwen and R.N. Bromilow CHAPTER 2.............................................................................................................................................................. 13 SOUTH-WESTERN LITTLE SANDY DESERT STUDY AREA S.J. van Leeuwen and R.N. Bromilow CHAPTER 3.............................................................................................................................................................. 33 FLORA OF THE SOUTH-WESTERN LITTLE SANDY DESERT S.J. van Leeuwen and R.N. Bromilow CHAPTER 4.............................................................................................................................................................. 65 HERPETOFAUNA OF THE SOUTH-WESTERN LITTLE SANDY DESERT P.G. Kendrick CHAPTER 5.............................................................................................................................................................. 85 BIRDS OF THE SOUTH-WESTERN LITTLE SANDY DESERT P.J. Fuller and A.A. Burbidge CHAPTER 6............................................................................................................................................................ 100 MAMMALS OF THE SOUTH-WESTERN LITTLE SANDY DESERT A.N. Start CHAPTER 7............................................................................................................................................................ 115 CONCLUSIONS AND RECOMMENDATION S.J. van Leeuwen * * * * * Table of Contents: iii EXECUTIVE SUMMARY The Little Sandy Desert is biologically a poorly known natural region in arid north-western Australia. The Desert is characterised by extensive red sand dunes and plains interspersed with resistant sandstone uplands. Overall, the biogeographical region is inadequately represented on the conservation estate with less than 5% reservation. This reservation is biased and consequently does not afford the biota comprehensive and adequate representation. This biological survey documents the flora and fauna of the south-western Little Sandy Desert and makes justified recommendations for reservation. The flora of the south-western Little Sandy Desert is diverse with 522 taxa. Many taxa are of biological and conservation significance and several were not previously recorded in the scientific literature. Many taxa are at the limits of their distributional range and are disjunct outliers of otherwise mostly northern or southern ranges. In broad terms the flora is dominated by central arid zone elements although southern and tropical arid zone groups are present. Floristic communities are readily distinguishable and their arrangement across the landscape appears to be controlled by topographic and edaphic considerations. The location of the study area in a transitional zone between major phytogeographic elements in the Australian flora together with heterogeneity in land surface types and soils is advanced as justification for the botanical diversity recorded. This diversity differs notably from other areas in the biogeographical region. The herpetofauna of the south-western Little Sandy Desert comprises 87 species (5 amphibians, 1 turtle, 9 agamids, 15 geckos, 5 pygopodids, 30 skinks, 9 varanids, 3 typhlopid, 1 boid and 9 elapids). It is highly likely that other species will be located within the study area as an additional 22 species are known from the biogeographical region. Most species are distributed widely in the northern or central arid zones although a significant number do not appear to pass beyond the fringes of the Desert, particularly on the western and southern margins. Surveys of the avifauna of the south-western Little Sandy Desert revealed the presence of 116 bird species (61 passerines, 55 non-passerines). A total of 42 species were recorded breeding after summer and winter-spring rains. Most birds recorded are typical of arid zone habitats in Australia, although 20 species of waterbird were recorded along Savory Creek. The birds tend to form weak assemblages which correspond to the main landform and vegetation types in the study area. Most birds however were ubiquitous because of their mobility, with the exception of a group favouring mulga woodlands. The terrestrial mammal fauna of the south-western Little Sandy Desert is comprised of 28 extant indigenous and seven exotic species. Given the evidence of past occurrences of three now locally or regionally extinct mammals in the study area, the indigenous fauna encompasses all but one of the mammals known from the biogeographical region. Spatially minor land surfaces are disproportionately important for mammals but differ in their relevance for indigenous and exotic species. Sandstone uplands have the richest indigenous fauna with six species restricted to this habitat. Loam and clay surfaces have the richest exotic faunas. Unequivocally, the south-western Little Sandy Desert supports a rich and diverse biota encompassing both ubiquitous and rare species, many of which are not known from the conservation reserve network. Consequently, to redress deficiencies in the comprehensiveness, adequacy and representativeness of the conservation reserve network in the biogeographical region, a proposal is tendered for the creation of the Giles Nature Reserve. This proposed nature reserve epitomises the physiogeographical character of Little Sandy Desert and is intrinsically representative of the biota of the region. Accordingly, the declaration of this proposed nature reserve would be a substantial gain for conservation. Executive Summary: 1 Chapter 1 THE LITTLE SANDY DESERT S.J. van Leeuwen and R.N. Bromilow Science Division, Department of Conservation and Land Management, Karratha. ABSTRACT The Little Sandy Desert is biologically a poorly known natural region in north-western Australia. The Desert experiences an arid tropical climate typified by hot summers and cool winters with mostly summer rainfall which averages 200 mm to 250 mm per annum. The salient characters of the Desert are resistant sedimentary uplands of mostly sandstone rising above extensive rolling eolian red sand dunes and sand plains. Significant uplands, typified by the Carnarvon Range are present, however relief is generally subdued. Drainage is mostly internal, easterly to north-easterly trending and along paleodrainage channels. The Desert is situated upon several geological structures most of which are Precambrian sedimentary basins. The Savory Basin is the most important of these sedimentary features and is completely encompassed within the Desert. Overlaying these sediments are Cainozoic deposits dominated by eolian sands although numerous examples of calcariferous, gypsiferous and lateritic deposits are also present. The Desert is mainly vegetated by Acacia, Grevillea and ericoid shrubs over hummock grasses although not insignificant woodlands of Eucalyptus, Allocasuarina and Acacia persist. Melaleuca and samphire heaths dominate most of the drainage features. The majority of the region is Unallocated Crown Land, although some parts of the Desert are within well-known reserves such as the Rudall River National Park and Canning Stock Route. At this time the region has limited financial prowess although the potential for hydrocarbons in the Savory Basin and the significant mineralisation associated with the Paterson Orogen in the Rudall River area may alter this situation in the future. Biological investigations in the Little Sandy Desert have been limited, mainly being confined to the Canning Stock Route and Rudall River areas. This situation was exemplified by the rediscovery of the only presumed extinct Eucalyptus (E. rameliana) in the southern portion of the Desert in 1991.