Introduction

There are few large offshore islands in Australia now free of fox (Vulpes vulpes) populations. Those remaining have a critical role in the conservation of Australian biodiversity. In 2001 the Tasmanian Parks and Wildlife Service reported that 11-19 foxes had been deliberately released into the Tasmanian environment. Although a Tasmanian Police investigation later found no evidence to support this claim, a fox eradication program (FEP) based upon widespread buried baiting with 1080 poison was underway by 2003. Key to the claims concerning the presence, distribution and eradication of foxes in Tasmania have been evidence based on opportunistically acquired post mortem specimens, anecdotal fox sightings and scat DNA data. Eradication strategies in Tasmania were proposed using data largely extrapolated from 1080 buried baiting trials from mainland Australia.

Why yet another scientific review?

The past reviews of the FEP have not attempted to systematically replicate, analyse or assess the precision of data generated by the program. Key assumptions and estimates concerning fox establishment, distribution and baiting efficacy remain untested. The potential for error to arise from techniques such as mtDNA scat surveys were not reviewed by experts in molecular biology or replicated by independent laboratories. Similarly, no detailed analysis of the use of anecdotal sightings nor the quality of opportunistically acquired physical evidence was undertaken. In contrast, our approach focused upon independently testing the quality of data used by the FEP using replication via experiment, statistical and comparative analysis and detailed review of the original source materials and citations.

We can’t afford to get this science wrong

Ensuring that wildlife management is based upon rigorous science is the best way to protect island ‘lifeboats’ of Australian biota from invasive species incursions. Unfortunately, the eradication of any vertebrate pest from a large land mass is extremely difficult to achieve and successes are rare (see our reality check here). There are no examples of fox eradication from islands even approximately 1% the area of the Tasmanian landmass using techniques similar to those employed by the FEP. It would be dangerous to overestimate and miscommunicate our present capacity to both detect and eradicate new fox incursions. It is absolutely essential to determine the different forms of error that influence data quality used to make estimates of population distribution, especially when they are used in ecological models. Overall, failing to adequately identify gaps in our knowledge and technical abilities means that improvement and innovation is not seen as a priority. Presently, fox incursions on other off-shore islands are likely to be managed using monitoring and eradication techniques similar to those applied in Tasmania. Claims made by the FEP and program reviews have significant implications for risk management of actual or speculative fox incursions on other Australian island reserves currently free of foxes.