Isles of Scilly Seabird Recovery Project

Protecting Scilly's Seabird for the Future

For centuries the Isles of Scilly have been a sanctuary for seabirds. Over the last 100 years their numbers have decreased significantly, as ground-nesting species struggle against invasive predators such as rats.  Nests are unsuccessful where rats are present, species such as Manx shearwaters and Storm petrels are particularly vulnerable to rats.

We know how to change this. By removing the biggest barrier to population recovery, seabirds can return, breed successfully and rebuild their colonies – securing Scilly’s future as one of the UK’s most important seabird habitats.

Eradication means removing every rat from an island so they cannot return and breed. This approach has been used on more than 700 islands worldwide, including St Agnes and Gugh, and has a very high success rate when done properly.

The eradication on St Agnes and Gugh was a huge success. Before 2013, Manx shearwater pairs totalled 22, now over 10 years post rat eradication there are almost 200 pairs!

Manx Shearwater Apparently Occupied Sites Scilly 2000 - 2025

The Isles of Scilly Seabird Recovery Project

A proposed eradication is currently being planned to remove brown rats from St Martin’s, Tresco, Bryher and around 21 nearby uninhabited islands

Because these islands are so closely connected, the operation must take place at the same time across the whole area. 
Special bait stations are placed across the whole island in a 50x50m grid pattern. 
These stations contain rodenticide bait, set out in late autumn when natural food is scarce. 
The bait is kept inside secure bait stations that exclude anything bigger than a rat.  
Teams check the stations at least twice a week, replacing bait and looking for signs of rats. 
Everyone involved is fully trained in safe rodenticide use and wildlife monitoring.

Scilly Seabird Recovery Project Proposed Rat Eradication Plan 2028 graphic

The project is currently in its development phase, and strides are being made to secure funding. In autumn 2024, a Feasibility Study was produced reporting that the Seabird Recovery Project is feasible. The Isles of Scilly Wildlife Trust is working with the Duchy of Cornwall, the Wildlife Trusts, and the RSPB, along with other organisations and local communities, to develop this project.

Since 2025, we have been running co‑design workshops and open days across the islands, giving the community space to share their knowledge, experience and insight. By working closely with islanders, the project is shaped not only to support our seabirds, but to deliver meaningful benefits for the community itself. The project hopes to bring improvements to food waste management, assistance with shed and garden clear-outs, and improvements that support local tourism.

The Isles of Scilly Seabird Recovery Project 2013-2017

The Isles of Scilly Seabird Recovery Project (IOSSRP) was successful, with St Agnes and Gugh declared rat-free in early 2017, however biosecurity actions to prevent the return of rats are still imperative. This was the largest community-based successful island restoration project in the world at the time.

IOSSRP set out to reverse recent declines in seabird populations on the Isles of Scilly through removal of non-native species (brown rats) from the islands of St Agnes and Gugh, and maintaining Annet and associated uninhabited islands as rat-free. It enabled people living on and visiting the Isles of Scilly to learn about, take pride in, and play an active role in celebrating and conserving their seabird heritage. It also trained and supported island communities to embrace the benefits of the seabird recovery and continue to protect their heritage once the project has ended.

The IOSSRP reformed in 2022 and confirmed that rats remained largest threat to burrow-nesting seabirds on land, so the feasibility of rat eradication is now being revisited on some of the other islands.