A trial on Te Pākeka/Maud Island for reducing aerial baiting sow-rates for the eradication of house mice

The house mouse (Mus musculus) is considered the most difficult rodent species to eradicate from islands. Eradication projects require careful planning and execution of an ‘over-engineering’ approach to ensure every individual of the targeted population is encountered and removed. Aerial broadcasting of rodenticides has been the method of choice for island rodent eradications since the 1990s and the methods and parameters continue to be refined. Mice were recently eradicated from Te Pākeka/Maud Island (318 ha) in winter 2019 using an aerial baiting prescription that was 50% less than the current best-practice baiting prescription. Using a rapid eradication assessment, it was proven that a combination of static and mobile surveillance devices could provide a high level of confidence of eradication success early on (4 months post-bait application). This paper describes the context, methodology, and outcomes of this low-sow rate trial in order to inform future projects. DNA profiling from the most recent mouse population established on Te Pākeka/Maud Island identifies the challenges of maintaining island biosecurity with the current available tools and in a context of increasing invasion pathways. The ability to adopt lower sowing rates for island mouse eradications reduces both financial and logistical barriers thereby allowing wildlife managers to implement mouse eradications on the world’s most remote islands.