Predator-free New Zealand 2050: Fantasy or reality?

Abstract

Possums, stoats, and rats introduced into previously mammal-free New Zealand (NZ) seriously impact our native flora and fauna. As a result, considerable research effort has focused on their control, with excellent success in the eradication of mammals from offshore islands. Unfortunately, we have run out of defendable, non-human occupied islands and the current focus is the NZ mainland, with a new government goal called Predator Free NZ 2050. In 2010, the Centre for Wildlife Management and Conservation started a research programme investigating new control and monitoring tools that could be used on the NZ mainland. More recently (2015) a privately funded research entity called Zero Invasive Predators Ltd (ZIP; both based at Lincoln University) was established with the goal of developing technologies to remove predators from large mainland areas and then defending them from reinvasion. ZIP has since demonstrated that a modified delivery technique for aerial 1080 can achieve near eradication of rodents and possums at two study sites. ZIP was then able to defend both sites in the short term using a virtual barrier of traps and/or geographical features such as rivers. The CWMC (with the Taranaki Mounga Project) investigated the use of self-resetting traps as a ground-based rodent control tool. The traps were unable to maintain average rodent tracking rates below 5% (avg. 11.5%) without regular trap servicing. To maintain low rodent numbers required a trap service every 3-4 months and this is not cost effective compared with alternatives. To improve detection rates the CWMC (with Cacophony Project) have shown that that thermal cameras are 3.6 times more sensitive than trail cameras for detecting possums. These cameras will quickly find survivors and/or reinvading animals using species recognition software combined with wireless communication. As Predator Free NZ 2050 scales up, more pest control will take place near urbanised areas. As such, the next focus should be the development of control tools with higher social acceptance. Surveys indicate the preferred control options are trapping and species-specific toxins. What this feedback highlights is that future research needs to reduce the cost of trapping so that it is affordable for community groups. In addition to this, funding is required for the registration of species-specific toxins, which have higher public acceptance.