Marion Island, South Africa 

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Marion Island, South Africa 

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Saving globally important seabirds

On windswept Marion Island in the sub-Antarctic, millions of birds, other animals, and plants are helpless victims to a dire threat. Accidentally introduced by humans in the 19th century, invasive House Mice are preying on Marion Island’s globally important seabirds and invertebrates, adversely impacting the vegetation and undermining the integrity of the island’s entire ecosystem. With each passing moment, this dangerous intruder poses an ever-growing threat to the remarkable biodiversity of Marion Island, compelling an urgent response to protect this important site and its cherished seabirds.

Marion Island is the larger of the two islands making up the Prince Edward Island Group in the southwest Indian Ocean. The islands are a South African territory in the sub-Antarctic and are designated as a Special Nature Reserve and a Marine Protected Area. The islands are also a Ramsar wetland of international importance.

The location of the Prince Edward Islands within the highly productive Southern Ocean makes it a haven for marine wildlife such as seabirds. The island group is home to almost half of the world’s Wandering Albatrosses, millions of other seabirds and a variety of other wildlife, some of which are found nowhere else in the world.

Without immediate action, many of Marion Island’s globally important seabirds face local extinction. A warmer and drier climate over the last 30 years has contributed to an increase in the densities of mice on the island each summer, causing a shortage of invertebrates, upon which the mice had been surviving in the winter months. This shortage of food has driven the mice to find other food sources.  The mice found that many of the seabirds had no defense against their attacks and are “sitting ducks”. The scale of attacks has been increasing since they were first observed in the early 2000s and has escalated dramatically in recent years.

In addition to the clear benefits to the birds and other biodiversity, the value of this conservation intervention reaches far beyond the island’s shoreline. Removing invasive mice from Marion Island will help secure the ecological integrity of this important sub-Antarctic Island and prevent the local extinction of 19 of the 28 seabird species that breed on the island. These birds bring important nutrients to the island from the sea through their guano deposits, which have flow-on effects for the integrity of the terrestrial and near-shore marine environments.

A Voice from the Field

"Due to the escalating impacts of invasive mice, Marion Island is unfortunately not the safe haven it used to be. Fortunately, we have the means to remove invasive mice from Marion Island. In doing so, we will address once and for all one of the significant threats to Marion Island’s biodiversity and ecosystem health. We are working hard to ensure that the Mouse-Free Marion Project has the best chance of success so that we can secure the island’s globally important seabird populations, and restore the ecological integrity of the island so that it can once again serve as a beacon of hope in the southern Indian Ocean."

— Dr Anton Wolfaardt, Mouse-Free Marion Project Manager

The Project

The eradication plan for Marion Island builds on years of scientific research and practical experience gained from over 700 successful rodent eradications on islands and from the few that have not succeeded. This has paved the way for the Marion Island operation which, at 30,000 hectares, will be substantially larger than previous rodent eradication efforts undertaken on islands in a single operation. The team is currently in the planning phase with implementation scheduled for 2026.

Project Partners & Funders

The Mouse-Free Marion Project is a partnership between the South African Department of Forestry, Fisheries and the Environment and BirdLife South Africa. A separate and special purpose entity, the Mouse-Free Marion Non-Profit Company, has been established by BirdLife South Africa to help implement the project. The project has received considerable support from leading institutions, organisations and philanthropists, both in South Africa and internationally.

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