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 act as 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, but also includes Martim Melo’s work in the Gulf of Guinea islands.

In terms of island restoration, 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. Despite the failure of the Gough Island Restoration Programme to eradicate mice from Gough Island in 2021, plans are underway to attempt to eradicate mice from Marion Island.

Activities in 2022

  • Maëlle Connan and Peter Ryan’s SANAP project continued to collect data on the predator-scavenger bird community on Marion Island, which is feeding into the planning process for the planned mouse eradication attempt on Marion Island.
  • Peter chaired an international panel that drafted a document assessing the likely impact of non-target species being poisoned during a mouse eradication attempt on Marion Island. Maëlle wrote much of the first draft of the report. Based on experience from eradications at other sub-Antarctic islands, coupled with experimental trials and feeding observations on Marion Island, six species were considered to be potentially at risk: Lesser Sheathbill Chionis minor, Brown Skua Catharacta antarctica, Indian Ocean Kelp Gulls Larus dominicanus judithae, the two species of giant petrels Macronectes spp. and Kerguelen Tern Sterna virgata. Of these, the resident sheathbill was considered to be most in need of possible measures to ensure its persistence on Marion. 
  • Susan Miller prepared samples from Lesser  Sheathbills collected on Marion, Prince Edward, the Crozet Islands and Kerguelen for DArTseq sequencing. The results, which should be available in the first quarter of 2023, will indicate the level of genetic structure within island populations of this species. This will inform whether it is reasonable to rely on Prince Edward Island as a ‘rescue’ population, should poisoning mortality of sheathbills on Marion Island be greater than anticipated during the eradication attempt.
  • Peter also serves on the Mouse-Free Marion Management Committee and chairs its Scientific and Technical Advisory Group.
  • Continued monitoring of the parasitic wasps released on Nightingale Island in April 2021 to control populations of the introduced Soft Brown Scale Coccus hesperidium and its associated Sooty Mould Seiridium phylicae on Phylica arborea trees confirmed that the wasps have become established and are causing significant mortality of scale insects. It is planned to release wasps on Inaccessible Island in early 2023.

Highlights

  • Peter Ryan and Steffen Oppel published a paper in Marine Ornithology that showed most adult Southern Giant Petrels Macronectes giganteus remain on Gough Island in the winter non-breeding period, and are thus potentially at risk from non-target poisoning in an eradication.
  • Martim Melo was lead author on a paper describing the elusive Príncipe Scops-Owl, which he first started looking for in 1998, when he was doing fieldwork on Príncipe Island for his Fitz CB project on the island’s Grey Parrot population. A local parrot harvester, Ceciliano do Bom Jesus, nicknamed Bikegila, told Martim that he had seen two owls roosting in a parrot nest. The tiny scops-owl, first photographed by birders in 2016, is named Otus bikegila after Bikegila, who now works as a ranger in the island’s natural park. Confined to Príncipe’s most remote forests, the paper recommends listing the scops-owl as ‘Critically Endangered’, providing further incentive to conserve the island’s remaining forests. 
  • A survey protocol for monitoring the Príncipe Scops-Owl population was developed combining automatic recording units with AI for retrieving the owl’s calls.

Impact of the project
This project has direct conservation benefits for island species, many of which have very small ranges and are listed as globally threatened.

Key co-supporters
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 SA; African Bird Club; TROPIBIO and BIOPOLIS programs of CIBIO.

Research team 2022
Prof. Peter Ryan (FIAO, UCT)
Dr Maelle Connan (NMU)
Dr Richard Cuthbert (formerly at the RSPB)
Dr Martim Melo (FIAO, UCT / CIBIO, U. Porto)
Dr Stefan Oppel (RSPB)
Dr Susan Miller (FIAO, UCT)
Andy Schofield (RSPB)
Dr Anton Wolfaardt (Mouse-Free Marion)

Research assistants:  Kim Stevens, Vonica Perold and Roelf Daling (Gough 2020/2022).021/22).