Above picture:  The combined takeover team.  From left Rabia Mathakutha, Monique van Bers, Elmar van Rooyen, Anton Wolfaardt and Camilla Smyth; photograph by Adrienne van Eeden-Wharton

Dr Anton Wolfaardt, Mouse-Free Marion (MFM) Project Manager, has recently returned from the 2024 annual relief voyage to Marion Island, when the meteorological and research teams who spend 13 months on the island are retrieved from the island and the new overwintering team are deployed.  The month-long voyage commenced when South Africa’s Antarctic research and supply vessel, the S.A. Agulhas II, sailed from Cape Town on 15 April 2024, docking in Gqeberha in the Eastern Cape on its return on 16 May 2024.  The main aim of Anton’s participation in the relief voyage was to continue with preparatory, planning and monitoring work for the MFM Project.

The MFM Project is also collaborating with Professor Michelle Greve of the Department of Plant and Soil Sciences, University of Pretoria (UP), on the project for which she is the Principal Investigator titled “Towards a comprehensive understanding of impacts of the invasive House Mouse on the terrestrial biodiversity of Marion Island”.  This project forms an important component of the long-term monitoring programme that aims to assess and track the ecological outcomes of the mouse eradication initiative.

Due to the collaborative nature of the two projects and the necessity for overwintering team members to work in the field together, including for safety purposes, team members were trained in the techniques required for both projects.  Members on the relief voyage were Anton and Rabia Mathakutha, South African Polar Research Infrastructure (SAPRI, in support of Michelle Greve’s project), and overwintering team members, Camilla Smyth (outgoing MFM Project Research Assistant), Monique van Bers (incoming MFM Project Research Assistant) and Elmar van Rooyen (incoming UP Research Assistant).

Camilla Smyth sets up a remote trail camera to record cloud levels on the slopes of Lou-se-Kop; photograph by Anton Wolfaardt

The annual relief voyage offered a valuable opportunity to review the past year’s work, provide training and orientation to Monique and Elmar, and finalise the research and monitoring plans for the coming year.  As part of the training and orientation, Anton, Camilla, Rabia, Monique and Elmar completed a ‘round-island’ excursion, staying overnight in the coastal field huts.

Last day of the ‘round island’. Walking from the field hut below Repetto’s Hill in the background to the research station – and a warm shower; photograph by Anton Wolfaardt

During the ‘round-island’ excursion, remote trail cameras were re-deployed at Lou-se-Kop in the north, Azorella Kop in the north-west, Swartkop Point in the west, and Grey-headed Albatross Ridge in the south.  These trail cameras take hourly photographs of inland reference peaks (with known elevations) during daytime hours to monitor the level and altitude of the cloud base.  These observations are used to gain a better understanding of how the cloud level experienced during the winter months, when the baiting operation will be undertaken, may typically impact the ability to use helicopters in different parts of the island.  This is a continuation of work that has been undertaken since 2022 and is intended to increase the sampling period.  Although prior data will not accurately predict the future, it will help inform the probability of suitable weather windows for helicopter-based baiting operations.

Back at the research station, the team conducted training, both in the field and in the laboratory.  The training and orientation focused on additional weather monitoring, various trials associated with bait monitoring, index trapping of mice to estimate their densities in different habitats and conducting vegetation and invertebrate surveys.  These activities helped to fine-tune the various monitoring protocols.

Camilla and Monique set up a bait trial in Nellie Humps near Trypot Beach; photograph by Anton Wolfaardt

Although the highest densities of mice are found in the coastal lowlands, their distribution extends to higher elevations, including the ‘polar desert’ habitat, albeit at lower densities.  Most previous research on Marion Island’s mice has focused on the coastal lowlands, where mice are more numerous and the study locations require less travelling time for researchers.  However, for the MFM Project, it is equally important to gather information on the lower-density mouse populations in the high-altitude habitats.  Consequently, several bait trials and density assessment transects have been undertaken or are planned for the island’s inland mountains.  The annual relief voyage provided an opportunity to plan and initiate some of this work.

Camilla and Elmar in the inland polar desert near the only high-altitude and inland field hut at Katedraalkrans, a very different habitat to the vegetated coastal lowlands in the distance; photograph by Anton Wolfaardt

The voyage also provided an opportunity to discuss logistical and regulatory aspects of the project with colleagues from the Department of Forestry, Fisheries and the Environment (DFFE), a key project partner.

The visit was productive, helpful, and hugely enjoyable, underscoring the magical and awe-inspiring nature of Marion Island.  It also emphasised the importance of the mouse eradication project.  Eliminating the introduced House Mice is crucial for securing the island’s ecological future.

Special thanks go to Sibusiso Mhambi, the DFFE Co-ordinating Officer (DCO) for the relief voyage, Daisy Kotsedi, the Assistant DCO, and Mntambo Nakwa, the DFFE Environmental Control Officer (ECO), for their leadership and support throughout the voyage.  Additionally, the DFFE and the Department of Public Works and Infrastructure (DPWI) both deserve congratulations for their combined efforts to remove the dismantled old research base from the island that would have acted as a refuge for mice.  Its removal contributes towards reducing one of the risks associated with the operational phase of the MFM Project.

Anton Wolfaardt, Mouse-Free Marion Project Manager, 09 July 2024

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At risk to mice. A Light-mantled Albatross by John Dickens and poster design by Michelle Risi

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.