Thanks to a grant from the Scottish Government’s Nature Restoration Fund, managed by NatureScot, two tern rafts have been created at RSPB Scotland’s Loch of Spiggie nature reserve in Shetland. Today’s guest blog explains how these floating platforms are helping the threatened seabirds.

With their long tail streamers, pointed wings and yearly mammoth migration, Arctic terns are often nicknamed the ‘sea swallow’. However, Arctic terns have a migration much longer than that of a swallow – spending summer as far north as the Arctic before travelling south during our winter for the Antarctic summer, which is a round trip of up to 22,000 miles each year. Some don’t make it as far as the Arctic though, and will instead spend the summer feeding and nesting in Scotland, including in Shetland.

Though they can be spotted inland during migration, they are mostly seen feeding on small fish like sandeels in shallow coastal waters and nesting on shingle beaches and coastal headlands. The terns reach their breeding grounds by May or early June, where each female lays one to three eggs in a shallow scrape on the ground. Unfortunately, Arctic terns are badly affected when sandeel populations decline. In 2004, large numbers of sandeels disappeared from many UK waters and scientists believe this was due to climate change. Arctic terns completely failed to breed in some areas that year, including Shetland, and their struggles have continued since.

In addition to food shortages, nesting terns face a number of other threats which reduce their breeding success. This includes disturbance by humans, predation by invasive species such as rats, and loss of habitat due to coastal erosion from increasingly unstable weather systems – another impact of climate change. Furthermore, the current strain of HPAI (Highly Pathogenic Avian Influenza) is having a devastating impact on seabird populations across Scotland. Great skuas and gannets have been particularly hard hit, but it is having an impact on terns too, which means it’s more important than ever to reduce external pressures on these birds where we can.

The decline in tern numbers over recent years is of real concern to RSPB Scotland, who, along with UK and international partners, is at the forefront of tern conservation efforts. Large-scale, long-term solutions are needed to address this issue in full, but there are things that can be done at a local level to help the birds in the meantime. In particular, floating platforms known as ‘tern rafts’ are a great way to provide a safe place for breeding terns to lay their eggs without the risk of predation or disturbance.

Thanks to a grant from the Scottish Government’s Nature Restoration Fund, managed by NatureScot, two tern rafts have been installed at RSPB Scotland’s Loch of Spiggie nature reserve in Shetland. The rafts were specially designed to create new nesting habitat for terns and are lined with shingle, shells and small shelters to imitate a natural nesting site. The addition of perspex sides prevents ground predators getting to the nest and by anchoring the platform in place the nests remain as static as possible, even in high winds. Though only recently installed, they have already been used by terns, with courtship and displaying behaviour witnessed. The birds using the rafts this year are likely sexually immature birds so won’t breed this summer, but the signs are good for future years.

The rafts are in a fantastic position for visitor viewing, where their importance as a measure to help nesting terns can be well communicated to a range of audiences, including school groups. RSPB Scotland also has a hide nearby. Here people can view the rafts in action along with new informative signage about Arctic terns which was also provided by the grant.

If the rafts become well used by terns RSPB Scotland may consider ringing the chicks and gathering information around survival rates from the rafts. It is hoped that the promising signs of tern activity increase in the coming years, with birds hopefully occupying the nesting rafts and providing a great “platform” for tern education.

Ruth Carruthers is Fundraising Manager at RSPB Scotland.

For more information:

https://www.rspb.org.uk/about-the-rspb/at-home-and-abroad/scotland/