Managing the risk of exotic vertebrate incursions in Australia

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Context Biological invasions are a profound contribution to human-induced environmental change. Although intentional introductions of vertebrate species have largely declined, global transport and communication networks continue to increase. As a consequence, more goods are being traded and the type of species being transported has changed, as well as the associated risks. Aims To analyse the frequency, and provide risk assessments, for exotic vertebrate species detected by border and post-border Australian biosecurity agencies in the past decade (1999–2010). Methods We collated detection records by emailing or telephoning representatives from agencies responsible for implementing Australian biosecurity. We calculated the risk of successful establishment (low, moderate, serious, extreme) for 137 identified vertebrate species not currently established in Australia. Generalised linear models were constructed to test whether the frequency of increasing risk of establishment was associated with either differences between vertebrate classes and/or different detection categories. Key results The majority of species detected were reported from illegal keeping. Individual species risk assessments revealed that reptiles were more likely to be of greater risk for future establishment than were birds, mammals or amphibians. Controlling for taxonomy, high-risk species were not involved in larger (i.e. number of individuals) incidents than were lower-risk species. Across years, the number of novel exotic vertebrate species detected ‘at large’ in Australia has significantly increased. Conclusions Several of the species detected by biosecurity agencies have attributes that give them the potential to become pests in Australia. Preventing incursions is by far the most cost-effective way to prevent future pest damage. Implications It is clear that a nationally coordinated framework for data collection and data sharing among agencies is urgently required. We present a minimum framework for the future collection of inter-agency data, necessary to assess and monitor the ongoing risk of vertebrate pest incursions in Australia.