Measured reductions in the density of camels under the Australian Feral Camel Management Project
Mark Lethbridge A D , Keith W. Saalfeld B and Glenn P. Edwards CA School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
B Department of Land Resource Management, PO Box 496, Palmerston, NT 0831, Australia.
C Department of Land Resource Management, PO Box 1120, Alice Springs, NT 0871, Australia.
D Corresponding author. Email: mark.lethbridge@flinders.edu.au
The Rangeland Journal 38(2) 173-179 https://doi.org/10.1071/RJ15106
Submitted: 20 October 2015 Accepted: 6 April 2016 Published: 5 May 2016
Abstract
In this paper we provide a coarse comparison between camel density estimates derived from aerial surveys conducted during the early and latter stages of the Australian Feral Camel Management Project, considering the number of camels removed between the surveys as a result of management intervention across three large and distinct geographic zones. Overall, despite the assumptions made during our analyses and possible errors associated with these, the post-aerial surveys in all three zones show a significant population decline compared with the corresponding pre-aerial surveys. The observed population decline in two zones (the Pilbara and that centred on the South Australia-Western Australia-Northern Territory border junction) were broadly consistent with the number of camels removed in each zone between aerial surveys. The population decline detected in the third zone (the Simpson Desert) was much greater than the known removals and there appeared to be another factor involved, possibly drought-induced natural mortality. We raise a number of concerns about making this type of comparison, including the limitations of working with a highly mobile species distributed across a broad landscape and the low number of aerial surveys available for this type of comparison due to a limited project monitoring budget.
Additional keywords: aerial survey, kriging, population modelling.
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