Strategic research for island restoration

Islands often have unique biodiversity. In the UK, many islands have retained large seabird colonies or semi-natural assemblages of waders, while globally many islands have species that occur nowhere else on the planet.

These endemic species are vulnerable to predators that were introduced by humans: around the world invasive vertebrates like rodents, feral cats, stoats, snakes, mink or mongoose have caused the extinction of many species.

To address this monumental threat we have to first secure those islands where dangerous predators have not yet been introduced to prevent any future introduction; second, on those islands where invasive species are already present we have to explore whether an eradication of the invasive species is possible. Eradications have restored hundreds of islands around the world, but there are thousands more where invasive species affect native biodiversity.

Our research aims to direct restoration efforts towards those islands where we could achieve the greatest benefit for biodiversity and conduct targeted research to prepare eradication and restoration programmes.

• Provide an inventory of all native and non-native vertebrate populations on islands in the UK, UK Overseas Territories, and the rest of the world.
• Develop strategic algorithms to assess the current or potential impact of invasive species on native biodiversity.
• Assess the feasibility of management approaches given island size and human inhabitants.
• Calculate the current and future impact of invasive species after invasion and/or eradication.
• Derive priority lists of islands where biosecurity or eradication of invasive vertebrates would lead to the greatest gains for biodiversity.
• Conduct feasibility studies and assess risk to native species to prepare eradication operations. 

We have compiled two databases of all the islands in the UK and in the UK Overseas Territories, with detailed information about the number of native and invasive species on each island, and the interactions between native and invasive species. Based on this information, we have compiled priority lists of islands for eradication across the UK and all the UK Overseas Territories, and we prioritised islands in the UK for rodent biosecurity.

For the key world heritage islands where rodent eradication is a priority (Gough, Henderson), we have conducted many preparatory studies to ascertain whether an eradication is necessary and feasible, and that native species are safeguarded during the operation.

On Henderson, we have also conducted detailed follow-up studies to investigate the consequences of the failed eradication in 2011 and how to improve a future operation.

For many islands, the status of knowledge of native and invasive species which live on the island is poor. Better surveys, and regular updates are needed to re-evaluate our approaches.

We plan to prioritise all islands in the Caribbean for biosecurity (2017) and all islands globally for feasible invasive vertebrate eradications (work led by Island Conservation, 2018).

For eradication operations that the RSPB is planning and implementing, we will establish monitoring programmes which allow us to document changes in island populations following the eradication.

• Island Conservation
• BirdLife International