Proceedings of the Vertebrate Pest Conference

Invasive house mice threaten native biodiversity on many of the world’s islands. Best practice for eradicating house mouse populations from islands currently relies on bait containing the anticoagulant rodenticide brodifacoum. These baits are typically either broadcast (by hand or by helicopter in natural areas) or placed in bait stations (in human infrastructure or in areas where open broadcast is not permitted). There have been many successful mouse eradications using these methods, including 29 of 36 attempts of islands being successful (81%) in New Zealand. Following recent failed mouse eradications on Gough Island (South Atlantic, 2021) and Midway Atoll (North Pacific, 2023), a workshop was convened with 24 people attending (16 in-person, 8 on-line) from 7 countries (Australia, Canada, France, NZ, South Africa, UK, US), to discuss some hypotheses for what may have contributed to these unsuccessful outcomes. The workshop was held in Palmerston North, New Zealand, between November 27 and 29, 2023. Discussions over the three days revolved around three hypotheses. We present the key factors hypothesized for why eradications failed on these two islands. We also outline research and operational needs that were identified in the workshop that can contribute to improved outcomes for future eradications of house mice from targeted islands.