[This post was made by Sophie Thomas who is a Project Manager working on seabird island restoration at the RSPB]

Ten years ago, the puffin population on Lundy Island in the Bristol Channel fell to an all-time low - five individuals on an island whose very name derives from the Old Norse for puffin. Since then, in the absence of black and brown rats, puffin numbers have started to recover – around 80 individuals were recorded on the island last year, and dozens more teased the warden by refusing to make land (meaning they couldn’t be included in the count).

Puffin by Andy Hay

Compared with islands like Sao Tome, the UK doesn’t impress hugely on the endemic species front. We do have a number of endemic species and subspecies – such as the Lundy Cabbage and its associated invertebrates, the St Kilda and Fair Isle wrens – but we fall well shy of the high levels of endemism associated with tropical islands. But what we lack in endemism, we make up for in spectacle – every spring and summer, huge, noisy and pungent seabird colonies assemble on many of the thousands of islands and islets that together make up the British Isles. I don’t often get to witness these spectacles as I tend to visit our seabird islands in winter - when the wind and waves impress in equal measure. I do this as part of our work to remove invasive species like rats from islands so as to secure a safer place for our seabirds to breed. The winter timing means we limit possible negative impacts of our work on other species whilst also increasing our chances of success.

These rat removal initiatives are crucial to our efforts to halt seabird declines and build resilience into bird populations that are facing uncertain futures due to climate change. In the face of such uncertainty, conservationists are trying hard to ensure we don’t have all our eggs on one island. At the moment, over 80% of the entire global population of Manx shearwater breed in the UK and Ireland, and 90% of them breed on three islands. OK, so all our (their) eggs aren’t on one island, but having 75% on just three islands doesn’t leave a lot of room for manoeuvre. Before the arrival of rats and other invasive, non-native species, birds such as Manx shearwater, Leach’s petrel and European storm-petrel will have bred more widely than they do now, and, ideally, we want them to recover their ranges to stand them in better stead for what lies ahead.

Manx shearwater chick by David Boyle

As a result of removing the rats from Lundy, the breeding population of Manx shearwater has increased more than ten fold (in ten years) to around 3,451 pairs. Overall, seabird numbers on the island have doubled since removing the rats. Similar benefits have been felt on other islands where we have removed invasive species. On our Ramsey Island reserve, an extra 3,000 pairs of Manx shearwaters (a 3.5 fold increase) now nest and storm-petrels have been recorded breeding for the first time.

Storm petrel by David Boyle

I recently met the Lundy Island warden and chatted about the success of the restoration project there. She said success for her is measured by visitors complaining of not being able to sleep for the eerie noises of the shearwaters returning to their burrows under the cover of darkness. Whilst not complaining, people are now expressing amazement at just how loud the birds are – plentiful seabirds leaving indelible memories sounds like success to me.

We continue to work to save our special seabird islands. We have recently tried to clear rats from St Agnes and Gugh in the Isles of Scilly (under international protocols, we have to wait two years before we can declare the rats officially gone), and are currently prioritizing the rest of the UK’s islands to see where our resources can be best invested to gain the greatest conservation benefit.

May 22 celebrated the International Day for Biological Diversity 2014. This year focus is on Islands Biodiversity. This is because islands and their surrounding near-shore marine areas constitute unique ecosystems often comprising many plant and animal species that are endemic—found nowhere else on Earth. The legacy of a unique evolutionary history these ecosystems are irreplaceable treasures. They are also key to the livelihood, economy, well-being and cultural identity of 600 million islanders—one-tenth of the world’s population. This blog is the last of four celebrating some of the island work that the RSPB is involved in.