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 focusses 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 at Gough Island and the uninhabited islands in the Tristan archipelago, as well as documenting the impacts of invasive invertebrates at these islands. 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, they have been found to attack seabird chicks on Marion Island, and plans are underway to try to eradicate the species at both islands.
Activities in 2017
- Regular surveys were conducted from March to May 2017 to monitor the spread of mouse attacks on large chicks of Grey-headed Albatrosses Thalassarche chrysostoma and sooty albatrosses Phoebetria spp. at Marion Island. Fewer birds were attacked than in 2015 and 2016, but the spatial extent of attacks was equally widespread as in previous years.
- Emma Witcutt and David Kinchin-Smith reported the first evidence of mice ‘scalping’ Atlantic Yellow-nosed Albatross Thalassarche chlororhynchos chicks at Gough Island during the 2016/17 breeding season.
- Field assistant Michelle Risi and MSc student Chris Jones, conducted a series of toxicity trials on mice on Marion Island to ensure that all mice that eat poison bait die. In fact they found that some mice survived when fed half a pellet, so additional trials are planned for 2018 with higher concentrations of the toxin brodifacoum. Michelle and Chris also conducted snap trapping near sea level, 300 m and 600 m to assess the decrease in mouse densities with elevation, which is crucial for planning baiting densities across Marion Island. They also monitored cloud heights around Marion over the winter to give some idea of the frequency of days with sufficient visibility for baiting by helicopter to take place.
- Ben Dilley and Delia Davies completed their first field season on Nightingale Island in early 2017 as part of an EU-BEST project awarded to Tristan Conservation to collect basic biology information on the Endangered Wilkins’ Bunting Nesospiza wilkinsi. They returned to Nightingale in September 2017 to obtain a second year of breeding data, as well as to re-sight as many banded buntings as possible for mark-recapture survival estimates.
- An unfortunate discovery during Ben and Delia’s second visit was the widespread presence of the invasive greedy scale Coccus hesperidum and localised infestations of its associated sooty mould Seiridium phylicae at Nightingale Island. Prior to this there was only a single record of the scale insect from Nightingale. The insect and sooty mould together significantly reduce the amount of Phylica fruit produced on infected trees, which has potentially serious implications for Wilkins’ Buntings that rely to a large extent on Phylica fruits for food.
- Sagina procumbens control/eradication operations continued on Gough Island throughout 2017. The new regime spraying with a combination of pre-emergent and standard herbicides appears to be making a difference, with decreasing numbers of seedlings detected in successive summers.
- During 2017 the RSPB finally announced that an eradication attempt for mice on Gough Island would take place in 2019. The plan will be supported logistically by the South African Department of Environmental Affairs (DEA).
- The donation of three helicopters and $100,000 to DEA by the Mamont Foundation, following the Antarctic Circumnavigation Expedition in March 2017, has stimulated DEA to announce plans for an eradication attempt on Marion in 2020, if the Gough eradication goes ahead as planned in 2019.
- A fund-raising programme to support the eradication of mice on Marion Island was initiated during BirdLife South Africa’s Flock at Sea cruise in April 2017, which attracted close to 2 000 birders.
- Dr Guy Preston from DEA presented a paper co-authored by Ben Dilley and Peter Ryan, reporting the impact of mice on Marion Island’s biota and indicating South Africa’s intent to launch an eradication for mice on Marion Island at the Third Island Invasives Conference in Dundee during July 2017.
- PhD student Otto Whitehead accompanied photographer Thomas Peschak to Marion Island in April-May 2017 and the impact of mice on the island’s birds will feature prominently in an article in National Geographic in mid-2018.
- Ben Dilley published a paper in Antarctic Science reporting how mice are causing low breeding success among burrowing petrels on Marion Island.
- The paper led by Airam Rodriguez, with Peter Ryan as one of many co-authors, reviewing the impact of light pollution on seabirds, primarily at their breeding islands, was published in Conservation Biology.
- Michael Brooke’s meta-analysis on the recovery of seabird populations following restoration programmes, with Ben Dilley and Peter Ryan as co-authors, was selected to be the main paper in an issue of Animal Conservation, with invited contributions from three leading restoration scientists and a response from the paper’s authors.
- Two papers on the clinical pathology of the endemic land birds of Gough Island, the Gough Bunting Rowettia goughensis and Gough Moorhen Gallinula comeri, were published in the Journal of Comparative Pathology. The studies, led by Mark Dagleish from the Moredun Institute in Scotland, forms part of the preparation for taking insurance populations of buntings and moorhens into captivity during the mouse eradication attempt on Gough Island planned for the winter of 2019.
Agreement on the Conservation of Albatrosses and Petrels; BirdLife International; DST-NRF CoE grant; EU-BEST; Royal Society for the Protection of Birds; South African National Antarctic Programme; UK Overseas Territories Environment Programme.
Prof. Peter Ryan (FIAO, UCT)
Dr Alex Bond (RSPB)
Dr Richard Cuthbert (RSPB)
Trevor Glass (Tristan Conservation Department)
Dr Ross Wanless (FIAO, UCT and BLSA)
Student: Ben Dilley (PhD).
Research assistants: Emma Witcutt, David Kinchin-Smith and Phil Lambdon (Gough 2016/17), Jaimie Cleeland, Kate Lawrence and Fabrice Lebouard (Gough 2017/18), and Delia Davies (Nightingale).