A programme to eradicate rats from Lundy Island has resulted in a tenfold increase in the population of Manx shearwaters.
Survey teams from the RSPB, funded by the Landmark Trust, National Trust and Natural England, returned to the island off the North Devon coast in the spring to check progress since the rat removal operation a decade ago.
Helen Booker, RSPB senior conservation officer in the South West, said: "This is such an exciting result, better than we expected, and the rate of increase is an indication of just how important rat-free islands like Lundy are as breeding site for seabirds."
The Lundy Seabird Recovery Project was launched in 2003 to recover the Manx shearwater population which then stood at just 300 breeding pairs. Ten years on, there are more than 3,000 pairs.
Puffin numbers have also increased from 5 to 80 while guillemots, razorbills and shags have also seen substantial increases.
Derek Green, Lundy General Manager said: "We are delighted with this result which is showing benefits for a range of species on the island and shows just how much can be achieved. Lundy has been a wildlife haven for many years, although rats were always a problem we had to live with.
"Their removal has transformed the island for both wildlife and visitors alike, and we're watching with great anticipation and excitement as the cliffs and slopes of Lundy fill with the eerie calls of thousands of birds once again."
It is hoped the striking results from Lundy will be repeated with the Isles of Scilly Seabird Recovery Project, on the islands of St Agnes and Gugh, which is due to start this summer.
The project is looking to secure populations of similar seabirds and the Scilly shrew.
Darren Mason, a volunteer with the project, is already working alongside local businesses, telling people about the important seabirds, the threats they face and what can be done to help.
"Our seabirds are amazing, long-lived birds but species like the Manx shearwater and storm petrel are particularly vulnerable as they nest in burrows and crevices where rats like to forage," he said.
"It is amazing to think that the storm petrel is a relative of the albatross, as they weigh the same as a few coins.
"I hope we will soon hear the delightful "purring" of these tiny ocean wanderers from many more places in the future as the result of the project."