Tiny storm petrels have now begun nesting on the Shiants, a few miles off the coast of Harris in the Outer Hebrides, following a major extermination project to kill a plague of black rats that had overrun the isles.
After the rats had been wiped out, ornithologists used a novel technique to attract the birds – speakers were set up to broadcast recordings of storm petrel calls, to signal a safe place to settle.
And the measures seem to be working, as the unmistakable sounds of real, live storm petrels has been detected from underground burrows on the islands and nesting behaviour has been witnessed.
“The churring of a storm petrel is very distinctive, and we’re delighted that it has been recorded on the Shiants this summer,” said senior project manager Dr Charlie Main.
“While we are still some way off the islands being officially declared rat-free, these calls indicate that all the biosecurity work we’re doing to keep these islands predator-free and make them ideal breeding sites for seabirds is paying off.”
The latest developments mark an important milestone for the Shiant Isles Recovery Project, which is funded by the European Union. The initiative, a collaboration between conservation charity RSPB Scotland, nature agency Scottish Natural Heritage (SNH) and the Nicolson family, which owns the islands, began in 2014 to provide safe breeding grounds for globally threatened seabirds.
Dr Andrew Douse, policy and advice manager for ornithology at SNH, added: “Storm petrels only occur on islands without rats, which means that they are very vulnerable to the effects that arise from invasive species such as these. The Shiants are an ideal breeding location for storm petrels and hopefully they will go on to become an important stronghold for this species.”
The islands host internationally important colonies of seabirds, including puffins and razorbills.
Black rats are thought to have arrived there after a shipwreck in the 18th century – a survey in 2012 estimated the population had reached at least 3,600, more in summer.
The rats are known to consume eggs and chicks of seabirds and their presence was having a major impact on ground-nesting species and preventing Manx shearwaters and storm petrels from breeding on the islands.
An eradication programme was completed in 2016, and the Shiants should be officially declared rat-free next March.