South Africa’s sub-Antarctic Marion Island is being devastated by introduced House Mice. The mice were introduced accidentally by sealers in the early 19th century, and over the last 200 years have caused extensive damage to the terrestrial ecosystems of the island. They have caused dramatic declines in the native invertebrate populations and depleted the seed stock of some indigenous plant species. More recently, the mice have started attacking the island’s globally important burrowing and surface-breeding seabird populations.
The increasingly warm and dry climate on the island and the lack of natural control factors have led to a 430% increase in the densities of mice over the last 30 years! The massive increase in the densities of mice on the island has caused a shortage of invertebrates, which the mice have been preying on in the winter months. This shortage of food has driven mice to find alternative food sources. As on several other oceanic islands, the mice found that many of the seabirds on Marion have no defence against their attacks and are literally ‘sitting ducks’.
The scale and frequency of attacks on seabirds have been increasing since they were first observed in the early 2000s and have escalated dramatically in the last five years. On Gough Island, mice are estimated to eat some two-thirds of eggs and chicks – some two million each year – and even attack adult birds! Left unchecked on Marion Island, the mice are likely to cause the local extinction of 18 of the 27 seabird species that breed on the island, including that charismatic icon of the open ocean, the Wandering Albatross.
In order to safeguard the island’s seabirds and facilitate its ecological restoration, there is an urgent need to eradicate the mice. A rigorous and systematic process has been followed to determine the feasibility of eradicating mice from Marion Island and, based on the outcome of the feasibility study, draft operational and project plans have been prepared.
The Mouse-Free Marion Non-Profit Company has been established to initiate and implement the project, which will be undertaken as a partnership between the Department of Environment, Forestry and Fisheries and BirdLife South Africa. In February this year, Dr Anton Wolfaardt was appointed as the Project Manager.
The project has gained significant momentum in recent months, but there remains a lot to do between now and the target date for the eradication, which is during the winter of 2023. Marion will be the largest island by far on which an attempt will be made to eradicate mice in a single exercise. Consequently, the logistical and planning demands are substantial, and there is an urgent need to raise the outstanding funding required for the project.
If you would like to help save Marion Island’s seabirds and contribute to the restoration of this globally important sub-Antarctic island, please consider contributing to our Sponsor a Hectare campaign at only R 1000 a hectare. Your support will help ensure a lasting conservation legacy.
Please follow this website for future news items, intended to be posted regularly from now on. You can also follow Mouse-Free Marion news on Facebook [https://www.facebook.com/Mouse-Free-Marion-1978098948867817]
Anton Wolfaardt, 17 March 2021
Recently appointed Project Manager, Anton Wolfaardt at Beauchene Island in the Falklands (© Leigh Wolfaardt)
Mouse-attacked Grey-headed Albatross chicks, Marion Island. (© Peter Ryan)
