Interior fences can reduce cost and uncertainty when eradicating invasive species from large islands

Bode, Michael, Brennan, Karl E. C., Helmstedt, Kate, Desmond, Anthony, Smia, Raphael and Algar, Dave (2013) Interior fences can reduce cost and uncertainty when eradicating invasive species from large islands. Methods in Ecology and Evolution, 4 9: 819-827. doi:10.1111/2041-210X.12072

Author Bode, Michael
Brennan, Karl E. C.
Helmstedt, Kate
Desmond, Anthony
Smia, Raphael
Algar, Dave
Title Interior fences can reduce cost and uncertainty when eradicating invasive species from large islands
Journal name Methods in Ecology and Evolution   Check publisher's open access policy
ISSN 2041-210X
Publication date 2013-09
Year available 2013
Sub-type Article (original research)
DOI 10.1111/2041-210X.12072
Open Access Status
Volume 4
Issue 9
Start page 819
End page 827
Total pages 9
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing Ltd.
Collection year 2014
Language eng
Formatted abstract
The conservation of many threatened species can be advanced by the eradication of alien invasive animals from islands. However, island eradications are an expensive, difficult and uncertain undertaking. An increasingly common eradication strategy is the construction of ‘interior fences’ to partition islands into smaller, independent eradication regions that can be treated sequentially or concurrently. Proponents argue that, while interior fences incur substantial up front construction costs, they reduce overall eradication costs. However, this hypothesis lacks an explicit theoretical or empirical justification.

We formulate a general theory that relates the number of interior fences to the magnitude and variation of the economic cost of island eradication. We use this theory to explore the conditions under which interior fences represent a defensible management strategy, under cost and risk minimisation objectives. We then specifically consider the forthcoming eradication of cats Felis catus from Dirk Hartog Island, Western Australia, by parameterising our general theory using published data on the cost and success of previous projects.

Our results predict that under a wide range of reasonable conditions, interior fences can reduce the expected cost of a successful invasive alien animal eradication from large islands. On Dirk Hartog Island, interior fences will marginally reduce eradication costs, with two fences reducing expected costs by 3%. Interior fences have a much more substantial effect on the variability of eradication costs: two fences reduce the width of the 95% confidence bounds by more than one-third and halve the size of the average project cost overrun/underrun.

Our results reveal that the construction of interior fences is a defensible management strategy for eradicating alien invasive species from islands. However, the primary benefit of interior fences will be risk management, rather than a reduction in expected project costs. 
Keyword Feral animals
Conservation fencing
Cost effectiveness analysis
Invasive species
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biological Sciences Publications
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