Above photo: A pair of Wandering Albatrosses in the midst of a courtship dance on Marion Island, Photo: Tom Peschak
How eliminating an invasive rodent pest will contribute to South Africa’s continued global commitments to halt biodiversity loss, restore ecosystems and ensure species resilience in the face of climate change.
The beginning of the austral summer marks the start of the hatching season for many of the breeding seabirds on Marion Island, South Africa’s sub-Antarctic territory. Despite the warmer weather, hatchlings on this remote island will face harsh environmental conditions. However, it is not the howling winds and chilly conditions that hinder the safety of defenceless chicks, but rather a diminutive yet voracious predator… the House Mouse.
Accidentally introduced to Marion Island in the early 19th century by sealers, invasive house mice have had a devastating impact on the ecology and biodiversity of Marion Island. Having greatly reduced the native invertebrate population and, in the absence of other food resources, these tiny predators have resorted to devouring live seabird chicks. Invasive species, especially mammalian predators such as rodents, are considered to be one of the leading causes of species extinctions on islands. Invasive species are responsible for 86% of recorded species extinctions on islands across the planet. At Marion Island, 19 of the 28 breeding seabird species are impacted by mice and are under threat of local extinction, directly as a result of mouse predation. It is clear that, in order to protect these species, including a quarter of the world’s population of Wandering Albatrosses, an urgent intervention is required. Otherwise, they may be lost to Marion Island forever.
Conservation measures that mitigate threats to pelagic seabirds are difficult to implement as these wide-ranging species ignore country boundaries, foraging widely across the vast open ocean, where they are exposed to a range of threats. Globally, seabirds are facing compounding threats from climate change, mortality at sea due to interactions with fisheries, and the impacts of invasive species. Indeed, seabirds are the most threatened group of birds in the world. At Marion Island, increases in the densities of mice are being driven by climate change, as a warmer and drier climate has allowed mice to extend their breeding season. The increasing population of mice on Marion Island is leading to increased predation on seabirds and invertebrates.
In isolation, these threats are a serious risk to species survival. But when these threats accumulate, the risks that these seabirds face become far greater. By removing or mitigating any one of these compounding threats, the seabirds will be more resilient in the face of climate change and other threats that impact their survival.
Removing invasive species from islands is the most tractable threat to address completely. In conservation terms, it is a highly effective intervention. Once invasive predators are removed, that threat is eliminated, and the species that have been impacted can start the process of recovery. Hundreds of eradication operations on islands around the world have shown the incredible rebounding of native seabirds and other biodiversity following the removal of invasive species.
The Mouse-Free Marion Project provides an opportunity to reverse the negative impacts caused by mice; an opportunity to turn back the clock. With many threatened species at risk on this globally important island, it is clear that safeguarding South Africa’s sub-Antarctic territory is a conservation priority.
Nations around the world have committed to halting biodiversity loss, restoring ecosystems and mitigating the impacts of climate change. In November 2022, world leaders, policymakers, civil society representatives and climate activists gathered in Egypt to find and implement solutions to the climate crisis at the annual United Nations (UN) Climate Change Conference (COP 27). Later that year policymakers gathered to discuss and implement solutions to halt global biodiversity loss at the UN Biodiversity Conference (COP 15) in Montreal, Canada. One of the more ambitious targets for COP 15 is the 30 by 30 pledge, the aim of which is to conserve 30% of the earth’s land and water surfaces by 2030. Previous targets, agreed at COP 10 in Aichi, Japan, have not been met, so there is renewed pressure to put in place the financial and political support needed. The stakes are high.
South Africa is a signatory to the Convention of Biological Diversity and has been part of the ratification of a number of conventions aimed at halting anthropogenic warming, including the Kyoto Protocol. With the Prince Edward Islands designated as a Ramsar Wetland of International Importance, South Africa has committed to conserving and restoring its Southern Ocean territory.
Recognising the risks to seabirds, an ambitious eradication operation is being planned for Marion Island that aims to eradicate mice from the island. This will ensure millions of seabirds have safe breeding grounds in the future. However, the mice are impacting much more than the seabirds, and eradicating mice will help restore the ecological integrity of the island.
There is an urgency to eradicating mice on Marion Island. Since the first record of mouse predation on seabirds in 2003, the mouse population has been expanding and the frequency of predation on seabirds has increased.
The Mouse-Free Marion Project needs to raise the majority of the funds needed for the eradication operation to proceed. This is surely the most important seabird conservation project that South Africa has ever undertaken. It will be a one-off intervention that, if successful, will immediately make a tangible difference to the breeding success of seabirds, and leave a significant conservation legacy.
The restoration of Marion Island’s ecosystem will be a key component in ensuring that South Africa honours its commitments to halting biodiversity loss, restoring crucial wetland ecosystems and increasing species resilience in the face of the climate emergency.
Robyn Adams, Communications Officer and Project Assistant. 14 March 2022
The Mouse-Free Marion Project is a registered non-profit company (No. 2020/922433/08) in South Africa, established to eradicate the invasive albatross-killing mice on Marion Island in the Southern Ocean. The project was initiated by BirdLife South Africa and the South African Department of Forestry, Fisheries and the Environment. Upon successful completion, the project will restore the critical breeding habitat of over two million seabirds, many globally threatened, and improve the island’s resilience to a warming climate. For more information or to support the project please visit mousefreemarion.org.