On 12 May 2021, South Africa’s Antarctic research and supply ship, the S.A. Agulhas II, returned to Cape Town following its annual relief voyage to Marion Island. I was fortunate to be able to participate in the five-week voyage to help inform our planning for the mouse eradication project, scheduled for the austral winter of 2023.

Offloading of the SA Agulhas II at Marion Island. Photo – Anton Wolfaardt

This was the first time that I have returned to Marion Island since spending a year there in 1994/95 as part of the 51st Overwintering Team. The visit was productive, helpful and hugely enjoyable, reinforcing what a truly magical and awe-inspiring place Marion Island is. The visit also served to highlight the importance and urgency of the mouse eradication project. Our visit coincided with the period at which mouse densities are at their highest on the island. Signs of their presence were ubiquitous – runways and tunnels criss-crossing most vegetated parts of the island.

Decades of research have demonstrated that the introduced mice are driving down densities of invertebrates, thereby undermining nutrient cycling and other important ecological processes on the island. More recently, the mice have started attacking and killing the island’s albatrosses and petrels, including large surface-nesting species such as the Wandering, Grey-headed and Sooty Albatrosses.

Marion Island supports a quarter of the global population of Wandering Albatrosses. Photo – Anton Wolfaardt

One of the things that struck me during this visit to the island is how much drier it appears compared to when I overwintered there 27 years ago. These drier and warmer conditions are beneficial for mice; it enables them to extend their breeding season, thus leading to continued increases in their numbers and exacerbated impacts on the seabirds and ecology of the island. Climate change models predict a continued amelioration in conditions for mice on the island, so these adverse impacts are likely to become even more severe.

Eradicating mice from Marion Island will not be an easy task. However, with meticulous planning, adherence to the lessons learned from successful eradications on other sub-Antarctic islands and the implementation of best-practice approaches, we know that it can be achieved.

In the few months that I have been involved with the project, I have been immensely impressed and inspired by the international community of experts in the field of island rodent eradication work. Their extensive knowledge and experience, as well as their enthusiasm and generosity in providing advice to the Marion project, has been magnificent.

The collective determination and efforts by colleagues within BirdLife South Africa, the South African Departments of Forestry, Fisheries and the Environment (DFFE) and Public Works and Infrastructure (DPWI), the many scientists conducting globally important research at Marion Island, some for many decades, and the members of the various advisory and management structures for the project, have been absolutely fantastic, and will certainly stand the project in good stead.

 

With members of the DFFE take-over team at Marion Island L-R: Mazizi Salmani, Daisy Kotsedi, Shiraan Watson (DCO), Mbulelo Dopolo, Brent Misrole, Anton Wolfaardt (Mouse-Free Marion), Mark Duckitt (Ecoimpact), Tatulo Fiphaza, Errol Julies. Photo – Bruce Dyer

All of these individuals and organisations are working together to achieve an outcome that will represent a significant and lasting conservation legacy: an island wilderness free of invasive mammalian predators, thus helping to secure an improved conservation status for the Wandering Albatross, the many other seabirds that call the island home, and indeed the ecological integrity of this important sub-Antarctic island.

Anton Wolfaardt, Mouse-Free Marion Project Manager, 14 May 2021