This partnership project between RSPB Scotland, Scottish Natural Heritage (SNH) and the Nicolson family, who have been custodians of the Shiant Isles for three generations, will provide safe breeding sites for some of Scotland's globally important seabird colonies.
The Shiant Isles are one of the most important breeding colonies for seabirds in Europe - around 10% of UK puffins and 7% of UK razorbills breed here every year. However, when the project began in 2014, as well as these amazing seabird populations, the islands were also home to invasive non-native black rats.
Black rats are were thought to have arrived on the Shiant Isles from an 18th century shipwreck. They occupied the main islands in the archipelago. In April 2012 a survey estimated there were around 3,600 rats on the islands, and this number increased significantly in the summer months when more food was available.
The invasive non-native black rats were known to consume the seabirds' eggs and chicks on the islands. Their presence was considered to be affecting the productivity of ground nesting species and discouraging other species like Manx shearwaters and European storm petrels from breeding there.
The project has two main stages; eradicating the invasive non-native black rats, and encouraging Manx shearwaters and storm petrels to breed on the Shiant Isles.
In March 2018 the Shiants were declared officially free of rats as a result of the project.
The rat eradication took place during winter 2015-2016 when rat numbers were at their lowest due to limited food availability, and when seabirds and other sensitive bird species were not on the islands. Led by Wildlife Management International Limited, which has had successes with similar projects around the world, the eradication was carried out by using rodenticide contained in bait stations set across each of the Shiant Isles, including the stacks. This took more than four months to complete.
Spending a winter on such remote islands in the Minch was extremely challenging, and the rugged terrain and steep cliffs made it even more so. An operational plan was developed following substantial research which made sure that this was achieved in the safest and most effective way.
Before this project began, similar eradication projects on other UK islands including Canna, Ramsey and Lundy had already been extremely successful. Manx shearwater numbers on Lundy increased tenfold in the 10 years since eradication, and storm petrels were recorded there for the first time in 2014. More recently, seabirds are already recovering in St Agnes and Gugh in the Isles of Scilly, following the declaration of their rat-free status in 2016.
From spring 2016 Manx shearwaters and storm petrels were encouraged to nest on the Shiant Isles, and in the summer of 2017 calling storm petrels were recorded on the islands for the first time. Breeding success of seabirds on the islands is being monitored to establish how they have benefited from the islands' restoration.
The abundance and diversity of the land bird populations has also been investigated, to see how they have responded to the change. Monitoring of the flora and invertebrate communities has taken place as well, to see how these communities have adapted.
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The Shiant Isles are ideal breeding grounds for Manx shearwaters and storm petrels. With the rats now removed, these islands offer a great prospect for these birds setting up a new colony.
To encourage Manx shearwaters and storm petrels to do so we are operating playback systems during the summer months. Speakers temporarily put on the cliffs broadcast the Manx shearwaters' haunting cackles and storm petrels' churring. These are known to draw in birds in the area, and are used by the Shiant Auk Ringing Group to capture and ring storm petrels around the islands.
The decline of invasive non-native black rats in the UK can be attributed to the arrival of brown rats which are larger and outcompete them. Since the eradication of black rats from Lundy, there were claims that the Shiant Isles had the only remaining UK population. This is not the case.
Although black rats are rare in the UK, evidence demonstrates that populations survive on other islands and in localised areas of the British mainland. Recent National Biodiversity Network data show populations around the UK, particularly in ports and port towns. This is supported by anecdotal records from London and Liverpool.
Black rats remain common and widespread throughout their historic natural range in Asia, where the population is stable and faces no known threat to its conservation status. The species is also common in large areas of the world where it has been introduced.
As well as bringing Manx shearwaters and storm petrels to the Shiant Isles, this project also aims to build UK expertise in island restoration, particularly biosecurity, to minimise the risk of future invasive species and the need for more of these projects. As part of this we have developed best practice guidance and training courses on biosecurity for seabird islands, and promoted the biosecurity measures for the Shiants to those most likely to visit the islands, to ensure they remain rat free. The project has paved the way for future island restoration projects to take place around Scotland and help the internationally important seabird populations.
The dramatic Shiant Isles rise up from the sea around five miles east of Harris in the Hebrides. Their name derives from the Gaelic Na h-Eileanan Seunta meaning "holy" or "enchanted" isles. This tiny cluster of islands is one of the most important seabird breeding sites in Europe and is designated as a Special Protection Area (SPA) to protect them.
Scotland's seabirds need our help. Between 2000 and 2012, 10 of the 16 monitored Scottish seabird colonies suffered from significant decline and Scotland and the UK have a global responsibility for these species - 80% of the world's Manx shearwaters breed around our shores.
The reasons for these declines are complex, and in many cases are related to changes in their prey. However, invasive non-native species like the black rat can have significant impacts on seabird species' ability to breed and in many cases make islands uninhabitable for seabirds. The RSPB is committed to doing everything it can to protect and restore our seabird populations and this project is part of that commitment.
Prior to the project beginning, at the peak of the breeding season the Shiant Isles were home to hundreds of thousands of seabirds including 10% of the UK population of puffins and 7% of the UK population of razorbills. It is hoped that many more will be able to breed successfully here following the islands' restoration.
As one of the most important seabird breeding sites in Europe the Shiant Isles are a designated Special Protection Area (SPA). However, both the populations of razorbills and guillemots on the islands are in unfavourable declining status. There is also evidence that suggests the puffin colony used to be more extensive.
Predation by black rats was an added pressure on the seabirds, combined with others including climate change, pollution, unsustainable fisheries and inappropriate development. This project aimed to help these populations and bring the SPA into favourable condition. By removing the rats, the seabirds now have a safer place to breed and a greater chance of successfully raising chicks, and more of these species may be attracted to nest on the islands.
Following the eradication the Shiants are being monitored and protected to keep them free of rats.
All island visitors need to be aware of the need for biosecurity. If you are visiting the Shiants please follow these five points:
For more information on biosecurity contact the RSPB Scotland Western Isles office on 01859 550280.
This project is a key part of ensuring that the future for seabirds on the Shiants Isles is more secure.
The UK has a global responsibility to protect its seabirds and the RSPB is taking action to help reverse their decline, through this project and others like it.
Now that they have a secure haven to breed, the seabirds on the Shiants are expected to have improved breeding successes, crucial to helping these struggling species.
Other seabird islands around Scotland also need restoring and the work done through the course of this project will be vital in guiding and informing future projects.
This project cost more than £1 million. Around half was funded through the EU LIFE+ programme. SNH also provided significant financial support. The remainder of the project was funded through donations.
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