Following a determination in 2015 that eradicating the mice from Marion Island was feasible, a detailed planning process, guided by internationally used methods, began. The eradication strategy for Marion Island builds on years of scientific research and practical experience gained from over 700 island eradications, the vast majority of which have been successful.

The Mouse-Free Marion Project’s eradication strategy is proven: a fleet of helicopters guided by GPSs and equipped with bait-application buckets will spread rodenticide bait across the entire island. This method ensures that every individual mouse will have access to the bait.

Decades of rigorous research and field experience have resulted in a specially crafted rodenticide bait that mice find irresistible. Bait pellets are robust enough to be dispersed aerially from a baiting bucket and remain potent and palatable long enough in severe weather conditions to be consumed by mice. The bait’s potency is carefully calibrated to avoid posing long-term risks to other species and to the environment. After the initial application, a second application will occur to ensure comprehensive exposure of every mouse to a lethal dose of the bait.


Although the Mouse-Free Marion Project builds on a solid foundation of successful prior eradications, it is not without challenges that must be overcome, including logistics, timing and scale:

  • At 30 000 hectares or 116 square miles, Marion Island is one of the largest island eradication efforts being planned and the largest island on which a rodent eradication will be attempted in a single operation. A fleet of helicopters with pilots skilled in successfully navigating the challenges of this eradication will be required.
  • The island’s remote location and the lack of an airfield require the transport of helicopters, fuel, pilots, project staff, bait and other essential project materials by ship.
  • The bait must be dispersed across Marion Island’s vast and rugged terrain of mountains, ridges, valleys and lava fields during the southern hemisphere winter when the food supply for mice is more limited. The weather conditions can be treacherous, with high winds, dense cloud and fog posing challenges to the most skillful pilots.

The technical planning for the Mouse-Free Marion Project addresses all of these challenges. Currently, the most significant challenge for the project is building a community of engaged donors committed to helping restore Marion Island. The challenges outlined above are costly to address, given the island’s large size and remote location. However, this once-off intervention will deliver conservation benefits in perpetuity, representing a significant return on the conservation investment.

Without strong philanthropic support to eradicate the mice, the island’s biodiversity will continue declining, leading to an ever more perilous future for the Wandering Albatross and other globally important populations of seabirds.