The Shiant Isles in the Outer Hebrides of Scotland have been officially declared rat-free, thanks to a four-year partnership project to restore them as a secure haven for nesting seabirds.

The Shiants, a remote cluster of islands five miles east of the Isle of Lewis, is one of the most important seabird breeding colonies in Europe, hosting around 100,000 pairs of nesting seabirds each year.

However, there was evidence that the invasive, non-native black rats fed on the seabirds’ eggs and chicks which was having a detrimental impact on their breeding success.

Rat-free status

With many seabird populations facing a multitude of threats and severe declines in Scotland and around the globe, it was vital that action was taken to safeguard those nesting on the Shiants.

An operation to eradicate the rats was carried out over the winter of 2015 to 2016, led by a New Zealand-based company Wildlife Management International Limited (WMIL), with the help of fifteen volunteers.

This stage was incredibly challenging due to the rugged terrain and steep cliffs that make up the islands, and the Hebridean weather conditions including severe storms. Since then regular monitoring for signs of rats has been carried out with none recorded.

The latest check was in February  meaning no evidence of rats had been recorded there for two years, the internationally agreed criterion for rat-free status.

The project was funded by EU LIFE+ in partnership with the Nicolson family, custodians of the islands for three generations, Scottish Natural Heritage and RSPB Scotland. It has also benefited from the help of many volunteers, and significant private donations.

Safeguarding seabirds

Over the last four years the project has focused on making the islands a safe place for seabirds to raise their chicks by removing the rats. 

It has been a huge success and played an important role in developing future island restoration and biosecurity work in the UK.

Another key part of the project is a programme of research monitoring the response of the ecosystem to the removal of rats.

It is anticipated that  puffins, razorbills, and guillemots will see improved breeding successes which could eventually lead to an increase in population of these seasbirds on the Shiants.

As well as the seabirds currently found on the islands, the Shiants offer suitable nesting habitat for European storm petrels and Manx shearwaters, two species of seabirds that are not generally found on islands with rats.

But the calling storm petrels, recorded on the islands last summer for the first time, gave a strong sign that the Shiants were free of rats ahead of the recent check.

Preventative measures

In order to ensure that the islands remain free of rats, and other mammalian predators, visitors are being asked to follow simple biosecurity measures.

This includes checking boats and kit for signs of rats prior to departing for the Shiants, and looking out for signs of them when on the islands.

Local boat operators along with SNH and RSPB Scotland staff have been trained in biosecurity measures by the project.

Dr Charlie Main, Senior Project Manager for the Shiant Isles Recovery Project said: “This is an absolutely fantastic moment for the Shiant Isles and everyone involved in the project is delighted that they are now officially rat free.

With so many of Scotland’s seabird populations in decline it’s vital that we do all we can to help them. Making these islands a secure place for them to breed is really important.

“Over the next few years we’re really looking forward to seeing the full impact of the islands’ restoration flourish with the seabirds enjoying improved breeding successes, and other species beginning to breed there as well. We’ll also continue to work with the local community to ensure this special place remains free of rats.

This project has paved the way for more island restorations to take place around Scotland and give our threatened seabirds the best possible chance for the future.”

Bright future

Andy Douse, Scottish Natural Heritage (SNH) ornithologist, said: “It’s wonderful news that this project has helped to protect the internationally important seabird colony on the Shiant Islands.

“The partnership between RSPB Scotland, WMIL, the Nicolson family and SNH has been a great success, particularly considering the complexity of the project, and we’d like to thank everyone involved.

“It was a great team effort, and we can now take the knowledge gained from this project into other work to protect Scotland’s special species and habitats.”

Tom Nicolson said: “”Obviously this is a tremendous story of success on so many levels. When the idea was presented to us six years ago, the pure logistics of the project seemed hugely ambitious.

“Now, knowing that new species are beginning to thrive on the islands, so soon after the project has finished, there are no limits to what the Shiants could become over the next five, ten, twenty years.

“It has been an immense pleasure working with such a talented and dedicated group of people from the RSPB and Scottish Natural Heritage – everyone involved should be thoroughly proud of themselves.”

This Author

Catherine Harte is contributing editor for The Ecologist. This story is based on a news release from RSPB.