Modelling the abundance of wildlife using field surveys and GIS: non-native sambar deer (Cervus unicolor) in the Yarra Ranges, south-eastern Australia
David M. Forsyth A C , Steve R. McLeod B , Michael P. Scroggie A and Matthew D. White AA Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, 123 Brown Street, Heidelberg, Vic. 3084, Australia.
B Vertebrate Pest Research Unit, NSW Department of Primary Industries, Forest Road, Orange, NSW 2800, Australia.
C Corresponding author. Email: dave.forsyth@dse.vic.gov.au
Wildlife Research 36(3) 231-241 https://doi.org/10.1071/WR08075
Submitted: 19 May 2008 Accepted: 19 February 2009 Published: 15 April 2009
Abstract
Combining abundance data collected in designed field surveys with biophysical data derived from geographic information systems is a powerful way to investigate predictors of spatial variation in the abundance of wildlife. We used such an approach to evaluate hypotheses about factors influencing the abundance of sambar deer (Cervus unicolour Kerr, 1792), a large non-native herbivore, in south-eastern Australia. We developed a spatial model for the abundance of sambar deer faecal pellets in a 3650-ha area in the Upper Yarra Ranges, Victoria. We counted the number of sambar deer faecal pellets along 100 randomly located transects and used a geographic information system to estimate biophysical variables around each transect. We formulated our hypotheses about how those variables might affect the abundance of sambar deer pellets into 22 candidate models and used the deviance information criterion to identify the ‘best’ model(s). Because five models had strong support we used model averaging to generate a predictive model. The three variables included in the predictive model were aspect (abundance of pellets declined with increasing ‘northerliness’ and increased with increasing ‘easterliness’), distance to water and elevation; the latter two variables were positively correlated and had a negative effect on the abundance of pellets. In contrast to previous models of sambar deer abundance in south-eastern Australia, our spatial predictions of the abundance of faecal pellets can be easily tested and updated. Our approach would be useful for modelling the abundances of other wildlife species at a range of spatial scales.
Acknowledgements
The study was funded by the National Feral Animal Control Program (Bureau of Rural Sciences), the Department of Sustainability and Environment (Land Management Branch), the Department of Primary Industries (Invasive Plants and Animals Branch) and Parks Victoria. We thank Ian Roche and Trevor Bulow (Parks Victoria) for providing access to the study area. Ryan Chick, Bruce Mitchell, John Mahoney, Graeme Coulson, and Ami Bennett helped to collect data. Brian Boyle and the late Geoff Moore provided important background information. We thank Graeme Newell, John Burley, Anne Dennis, Brian Boyle, Glen Jameson, John Wright, Ami Bennett, Rob Allen, Andrea Taylor, and two anonymous reviewers for comments on previous versions of the manuscript.
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