An evaluation of transect, plot and aerial survey techniques to monitor the spatial pattern and status of the bilby (Macrotis lagotis) in the Tanami Desert
Richard Southgate A B E , Rachel Paltridge C , Pip Masters B and Theresa Nano DA Biodiversity and Conservation Unit, Department of Infrastructure, Planning and Environment, Alice Springs, NT 0871, Australia.
B PO Box 305, Kingscote, SA 5223, Australia.
C Desert Wildlife Services, PO Box 4002, Alice Springs, NT 0871, Australia.
D Central Land Council, PO Box 3321, Alice Springs, NT 0871, Australia.
E Corresponding author. Email: southgate@kin.net.au
Wildlife Research 32(1) 43-52 https://doi.org/10.1071/WR03087
Submitted: 16 September 2003 Accepted: 22 October 2004 Published: 25 February 2005
Abstract
We evaluated three monitoring techniques to determine the spatial pattern and relative abundance of the bilby (Macrotis lagotis) in the Tanami Desert, Northern Territory. All the methods examined relied on the identification of animal sign (foot imprints or diggings) to indicate the presence of a species. With fixed transects, a 10-km prepared tracking surface was monitored regularly using an all-terrain vehicle. With random plots, an unprepared tracking surface within a 200 × 300 m area was searched on foot for sign of the species. A helicopter was used in an aerial survey to identify bilby diggings from an altitude of 15–20 m while travelling at a speed of 30–40 knots along a predefined transect. The results for each method were stratified in relation to latitude and substrate to facilitate comparison of the efficacy of each technique. The fixed transects returned the least number of bilby records for most effort. The aerial transect technique resulted in few (<4%) false negative records but a sizeable (42%) number of false positive records. It is suggested that the aerial survey technique combined with ground-truth survey plots would provide reliable information on the extent of occurrence and status of the bilby in the remote spinifex deserts of central Australia.
Acknowledgments
We thank Grant Allan and Julian Reid for input regarding the development of the random plot technique for sampling. We are indebted for the assistance provided by Aboriginal people accompanying us on the field trips, including Pharlap Dixon, Engineer Jack, Shorty Jangala, Darby Jampitjinpa, Irene Dixon, Tommy Driver, Jerard Driver, Lynnette Driver, Cindy Bartlett, Neville Poulson and Sarah Napangangka. Chris Grant assisted with data collection during part of the random plot survey. We thank the helicopter pilots Craig Wherliman, Nathan Covy and Mick Burbidge for their assistance. Bill Freeland, Tony Bowland, Glen Edwards, Sue Carthew and Hugh Possingham provided valuable comments on the manuscript. Finally, the study could not have been completed without the support of the Northern Territory Parks and Wildlife Commission and funding from the Natural Heritage Trust. Part of the funding for the aerial survey was provided by the Easter Bilby fund supported by Coles Myer.
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