Mouse-Free-Marion Project support

Marion Island is part of the Prince Edward archipelago. It is located in the subantarctic zone about halfway between South Africa and Antarctica (1,769 kilometres southeast of Port Elizabeth in South Africa). With a length of 25 km and a width of 17 km, it is significantly larger than the neighbouring island of Prince Edward. Both islands were formed by volcanic activity. The archipelago has been part of South African territory since 1947 and has been declared a Special Nature Reserve by the South African Environmental Management.

The highlight of Marion Island is, without doubt, the two million individual seabirds. Among them is the wandering albatross (Diomedea exulans), the iconic bird of literature and legends that has been considered a powerful harbinger of hope and good fortune for centuries. Furthermore, several species of penguins also inhabit the island, such as the gentoo penguin, king penguin, macaroni penguin, and southern rockhopper penguin. The more than 175,000 breeding pairs on the Prince Edward Islands account for about 13% of the world’s king penguin population.

Currently, 28 seabird species breed on Marion Island, including endangered species such as the grey-headed and sooty albatross.

During the 19th century, house mice (Mus musculus) were unintentionally introduced to Marion Island by sailors. Due to the lack of natural predators on the island, the mouse population has spread enormously over the years. It now poses a severe threat to the island’s ecology, especially its resident breeding bird species. Some of the native bird species on Marion Island cannot be found anywhere else. Due to a lack of food sources, mice have specialised in eating seabirds for several years. The voracious mice attack eggs, chicks, juveniles, and increasingly even adult birds.

If this development continues undisturbed, it could lead to the local extinction of 18 of Marion Island’s 28 resident breeding birds, some as early as within the next 30 years. 

For this reason, BirdLife South Africa has launched the Mouse-Free Marion Project to wipe out the mouse population on Marion Island. So far, the project has been funded through various core partnerships with local and international organisations, crowdfunding campaigns and the South African government.

The eradication of the invasive mice on the approximately 300 square kilometre island requires a well-thought-out methodology and years of preparation. The method is based on knowledge from comparable projects in South Georgia and on Gough Island in the South Atlantic. The plan is to have a fleet of helicopters capable of deploying rodenticides with mouse-specific baits in every potential mouse habitat across the island. This is the only method that has so far proven successful in removing rodents on large sub-Antarctic islands.