The Shiant Isles have been completely cleared of black rats, after an intensive eradication scheme which cost £900,000.
The rats, which arrived on the islands in wrecked ships, harmed native bird populations by eating eggs and young chicks.
Thousands of the invasive vermin were destroyed as part of RSPB Scotland’s Seabird Recovery Project, which was awarded £450,000 in European Union funding, and was also supported by a £200,000 grant from Scottish Natural Heritage.
The remaining £250,000 was raised through donations.
George Campbell, RSPB regional director for north Scotland, said: “Scotland’s seabirds are suffering chronic declines and we have a responsibility to do everything we can.
“Eliminating the invasive rats on the Shiant Isles ensures safe breeding sites for struggling seabirds and allows the recovery and restoration of the island’s existing colonies, as well as encouraging Manx shearwaters and storm petrels to breed there.”
Tom Nicolson, owner of the Shiant Isles, told www.welovetheisleofharris.com: “This is real progress for the future of the Shiant Isles.
“I feel the work that has been carried out this winter has sent the islands onto a different, more prosperous course that will be felt for generations, even centuries to come.
“For over 150 years the sea-life and wildlife of the Shiants has been suppressed by the black rat - a visitor artificially introduced into the population when a ship crashed off the coast of the islands.
“We will now see what the islands should have become.”
The Shiant Isles are one of the most important breeding colonies for seabirds in Europe – around 10 per cent of UK puffins and 7 per cent of UK razorbills breed there every year.
Black rats are thought to have arrived on the Shiant Isles from an 18th century shipwreck.
In April 2012 a survey estimated there were around 3,600 rats on the islands – this number increased significantly in the summer months when more food was available.
The invasive non-native black rats were known to consume eggs and chicks on the islands.
Their presence was considered to be impacting the productivity of ground nesting species and preventing other species like Manx shearwaters and European storm petrels from breeding there
The Shiant Isles support around 10% of the UK’s puffin population and 7% of the UK’s razorbills.
The island group is a Special Protection Area for wild birds.