Conserving islands and their birds
Oceanic islands hold a disproportionately large amount of terrestrial biodiversity, yet are extremely vulnerable to introduced species: more than 90% of recent bird extinctions have been of island birds. Fortunately, eradicating invasive species can restore island ecosystems, provided there are strict controls on the subsequent import of people and materials. Birds are flagships for the conservation-management and restoration of island ecosystems. Our work centres on South Africa’s Prince Edward Islands and the UK Overseas Territory of Tristan da Cunha and Gough Island.
This programme is mainly concerned with the impacts of introduced predators, especially House Mice Mus musculus, but also is involved in the eradication or control of introduced plants and invertebrates. The impacts of House Mice on seabirds were only discovered in the early 2000s, following research by Fitz students in collaboration with the Royal Society for the Protection of Birds (RSPB) at Gough Island. Since then, mice have been found to attack seabirds on Marion Island, and plans are underway to try to eradicate the species at both islands. The COVID-19 pandemic caused the postponement of the Gough Island Restoration Programme attempt to eradicate mice from the island from 2020 to 2021. However, on a more positive note, considerable progress was made with planning for the proposed mouse eradication on Marion Island, and action was taken against invasive species at Tristan da Cunha.
Activities in 2020
- A paper on the ongoing spread and rapid increase in impact of the introduced Soft Brown Scale Coccus hesperidium and its associated Sooty Mould Seiridium phylicae on Phylica arborea trees at Inaccessible Island, and its arrival on Nightingale Island, was published in Biological Conservation. Because the fruit of these trees is crucial for the large-billed Nesospiza finches on these islands, the findings prompted the RSPB to raise emergency funding to launch a biocontrol programme to limit the populations of Soft Brown Scale using parasitic wasps.
- The RSPB also arranged for another expedition to remove invasive New Zealand Flax Phormium tenax from Inaccessible Island.
- Post-doc Ben Dilley finalised two papers on Wilkins’ Finches Nesospiza wilkinsi, a naturally extremely rare finch confined to Nightingale Island in the Tristan da Cunha archipelago. One paper on the finch’s home range and population size is in press with Ardea. The other paper, contrasting the finch’s breeding biology with that of the sympatric Nightingale Finch N. questi, is in press with the new online journal Afrotropical Bird Biology.
- Peter Ryan was involved in progressing plans to eradicate House Mice from Marion Island. Peter serves on the Mouse-Free Marion Management Committee and chairs its newly-constituted Scientific and Technical Advisory Group. He gave a presentation on the need for the eradication to Barbara Creecy, Minister of Environment, Forestry and Fisheries.
- Former MSc student Chris Jones led on a paper, recently published in Emu – Austral Ecology, that assesses the demographic impacts of House Mice predation on MacGillivray’s Prions Pachyptila macgillivrayi on Gough Island. Virtually all the world’s population of this seabird occurs on Gough Island, and breeding success is extremely low due to mouse predation. Ben Dilley published a similar paper on the impacts of Black Rats Rattus rattus on a colony of Broad-billed Prions Pachyptila vittata breeding in a coastal cave at Tristan da Cunha in Ostrich.
- A paper on the distribution and relative abundance of the Inaccessible Island Rail Atlantisia rogersi was published in Bird Conservation International, showing that the species remains common throughout Inaccessible Island, which is free of introduced predators.
- Martim Melo, with colleagues at the California Academy of Sciences and the University of Lisbon, worked towards creating a Gulf of Guinea Biodiversity Centre. The aim of this organisation, based on São Tomé Island, is to promote research, education, and conservation on this very important centre of endemism. An inaugural meeting with some 50 founding members from diverse institutions took place in October 2020. (see http://gulfofguineabiodiversity.org).
- Considerable progress was made with plans to eradicate mice from Marion Island. Peter Ryan serves as a Director of the Mouse-Free Marion non-profit company set up to manage the operation as a partnership between the South African government and BirdLife South Africa. Anton Wolfaardt has been appointed as Project Manager from 1 February 2021, and an Operations Manager will be recruited on a part-time basis later in 2021.
- Emergency funding from the Darwin Fund has allowed the rapid screening of potential biocontrol vectors against Soft Brown Scale at the Tristan archipelago. After six months of trials, a preferred species of wasp has been identified, bred in captivity, and transported to Tristan da Cunha for a trial release on Nightingale Island in early 2021.
- Five papers were published in the peer-reviewed literature, with a further three papers in press.
Agreement on the Conservation of Albatrosses and Petrels; BirdLife International; DSI-NRF CoE grant; EU-BEST; Royal Society for the Protection of Birds; South African National Antarctic Programme; UK Overseas Territories Environment Programme, BirdLife South Africa.
Research team 2020
Prof. Peter Ryan (FIAO, UCT)
Dr Alex Bond (formerly at the RSPB)
Dr Richard Cuthbert (formerly at the RSPB)
Dr Ben Dilley (FIAO, UCT)
Dr Martim Melo (FIAO, UCT /CIBIO, U. Porto)
Dr Stefan Oppel (RSPB)
Dr Susan Miller (FIAO, UCT)
Andy Schofield (RSPB)
Research assistants: Chris Jones, Michelle Risi and Alexis Osborne (Gough 2018/19 and 2019/20); Kim Stevens, Vonica Perold and Roelf Daling (Gough 2020/21).