John Cooper (Centre for Invasion Biology, University of Stellenbosch)
Dr Richard Cuthbert (Royal Society for the Protection of Birds, UK)
Oceanic islands – those that have never been connected to a continental landmass – are among the most sensitive of terrestrial ecosystems. Large surrounding stretches of open sea prevent many elements typical of continental biotas from colonising these islands. The few terrestrial species that do manage to reach the islands often evolve into endemic species, many of which lack appropriate defences against introduced predators, or are unable to cope with introduced competitors. Colonisation of these environments by man and his commensals has had catastrophic results – more than 90% of avian extinctions since 1600 have been of island taxa. Even where species persist, they are often at greatly reduced population sizes, and are thus prone to extinction from chance events such as environmental variability and catastrophes. Land-bridge islands are less susceptible to disturbance, but off southern Africa all are small, and support large numbers of breeding seabirds, many of which are endemic to the region and globally threatened. Conservation of these breeding sites is thus of considerable importance. This programme dovetails with the Seabird Research Programme, but covers the broader issues of island conservation, including the control of alien organisms and conservation of land birds on islands.
The impacts of mice on the birds of Gough Island
Research Team: Richard Cuthbert, Peter Ryan
We initially suspected that introduced House Mice Mus musculus were serious predators of bird chicks on Gough Island following field work there by Richard Cuthbert and Erica Sommer in 2000/01. This was subsequently confirmed by studies conducted by Ross Wanless for his PhD at the Fitz. We now know that mice attack the chicks of at least five seabirds on the island, and we suspect they are responsible for massive population decreases in almost all seabirds, as well as the endemic Gough Bunting. The bunting and the near-endemic Tristan Albatross are now listed as Critically Endangered largely as a result of mouse predation. Current research is focused on establishing the feasibility of eradicating mice from the island without lasting impacts on the island’s native fauna. This project, funded through the Royal Society for the Protection of Birds, is supported logistically by the South African National Antarctic Programme.
Tackling invasive plants at Tristan da Cunha and Gough Island
Research Team: Richard Cuthbert, John Cooper & Peter Ryan
The species native to oceanic islands are particularly susceptible to the impacts of invasive species. The uninhabited islands of Tristan da Cunha and Gough Island are among the least modified temperate islands in the world, but several alien plants have become established on the islands. This project, working through the UK’s Overseas Territories Environment Programme, is tackling some of the invasive species that still have localized ranges. The main target species are New Zealand Flax Phorium tenax on Inaccessible and Nightingale Islands and Procumbent Pearlwort Sagine procumbens on Gough Island.