The untamed shrew : on the termination of an eradication programme for an introduced species

Summary 1  One option in managing introductions of non-native pest species is to eradicate the introduced species by trapping or otherwise removing individuals. A central issue in undertaking such a programme is deciding when it is reasonable to terminate the programme because all individuals have been removed. This decision requires knowledge of the probability that complete eradication has been achieved. 2  An objective Bayesian method is presented to determine the probability that all individuals of an introduced species have been removed. The method is based on the excess trapping times of individuals beyond a specified threshold, assuming a generalized Pareto distribution for excess trapping time. 3  The method is applied to data from an unsuccessful trapping programme of the Asian musk shrew Suncus murinus on the Mauritian island of Ile aux Aigrettes. The results suggest that, had the method been used, managers would have realized that the probability of complete eradication was not high and premature termination could have been avoided. 4 Synthesis and applications. A central issue facing the manager of an eradication programme for an introduced or pest species is deciding when it is reasonable to terminate the programme because all individuals have been removed. If termination is premature, the programme will fail; if termination is delayed beyond the point of eradication, unnecessary costs will be incurred. The statistical method described here for calculating the probability of complete eradication based on the record of removals provides information that is useful either in an informal assessment of progress or in more formal decision making regarding termination.

[1]  M. A. Amaral Turkman,et al.  Bayesian approach to parameter estimation of the generalized pareto distribution , 2003 .

[2]  Elja Arjas,et al.  Bayesian removal estimation of a population size under unequal catchability , 2005 .

[3]  S. Harris,et al.  Mechanisms underlying the failure of an attempt to eradicate the invasive Asian musk shrew Suncus murinus from an island nature reserve , 2005 .

[4]  Lynn Kuo,et al.  Bayesian Computation for Nonhomogeneous Poisson Processes in Software Reliability , 1996 .

[5]  A. Raftery.  Inference and Prediction for a General Order Statistic Model with Unknown Population Size. , 1987 .

[6]  A. S. Cheke,et al.  Studies of Mascarene Island birds: An ecological history of the Mascarene Islands, with particular reference to extinctions and introductions of land vertebrates , 1987 .

[7]  Peter W J Baxter,et al.  Optimal eradication: when to stop looking for an invasive plant. , 2006, Ecology letters.

[8]  Kenneth H. Pollock,et al.  Modeling capture, recapture, and removal statistics for estimation of demographic parameters for fish and wildlife populations : Past, present, and future , 1991 .

[9]  Simon P. Wilson,et al.  Statistical methods in software engineering , 1999 .

[10]  A. Solow.  Inferring Extinction from Sighting Data , 1993 .

[11]  Thomas S. Ferguson,et al.  Stopping rules for proofreading , 1989, Journal of Applied Probability.

[12]  Andrew R Solow,et al.  Inferring extinction from a sighting record. , 2005, Mathematical biosciences.

[13]  J. Pickands.  Statistical Inference Using Extreme Order Statistics , 1975 .

[14]  T. Fritts,et al.  THE ROLE OF INTRODUCED SPECIES IN THE DEGRADATION OF ISLAND ECOSYSTEMS: A Case History of Guam1 , 1998 .