A MAJOR project, costing almost £1 million, is being launched to arrest the decline over the past 30 years of Scilly's colonies of storm petrel (the only ones in England), Manx shearwater and puffins, of which some 25 per cent have been lost.
This stark depredation statistic is being addressed by a 25-year partnership project starting early this year to provide a safe future for the islands' internationally-important seabird populations.
Funding totalling £800,000 to £900,000 is coming from the Heritage Lottery Fund (HLF) and the EU LIFE programme with help from Natural England, the islands' wildlife trust, Duchy of Cornwall and the local AONB Sustainable Development Fund.
Scilly is home to breeding populations of 14 species and approximately 20,000 birds.
The project's aims, protection and restoration apart, are to increase the number of people involved in conservation, and to help the islands to make the most of these assets by providing better access for people.
Rats are a major threats to the eggs and chicks. Rodent control work over the past 15 years on Scilly's uninhabited islands has left them rat-free.
The idea of extending eradication to the inhabited islands emerged nine years ago when it was discovered that rats swimming from St Agnes had decimated seabird populations on neighbouring Annet.
Most of the work will take place on St Agnes and Gugh between now and 2018-19.
It is estimated that 3,000 brown rats will be removed.
Arguably St Agnes had a stronger seabird heritage than any of Scilly's inhabited islands, said islander Richard McCarthy.
"It was home to its own bird observatory in the 1950s and 1960s and also for more than 25 years to Hilda Quick whose book, Birds Of The Isles Of Scilly was published in 1964.
"Today, the Turk's Head pub continues to host a nightly bird log each October," he said.
Mr McCarthy said a feasibility study had confirmed rats as the biggest threat to the islands' breeding birds.
"But it also indicated that where there were human settlements rat removal was only worth pursuing for the time-being on St Agnes and Gugh.
"Waste and the sheer density of building in Hugh Town is the issue on St Mary's while, because of their proximity to each other, trying to keep Bryher, St Martin's and Tresco simultaneously rodent-free was deemed a challenge too far, given the ability of rats to survive in water, swim several hundred yards and to do so readily."
The RSPB's conservation officer for Scilly, Paul St Pierre, said: "UK seabird populations are some of the most important in the world. We need to make sure we look after them."
A project manager has been appointed and invitations to tender for the rat removal work have gone out to organisations, not just in the UK but as far afield as Australia and New Zealand.
David Mawer, of the islands' wildlife trust, said: "This will bring many benefits to wildlife, locals and visitors, and crucially will safeguard Annet – Scilly's most important seabird reserve.
"The successful removal of rats from St Helen's resulted in a dramatic increase in the number of Manx shearwaters breeding there. The eerie cries and shadowy silhouettes of seabirds at dusk could soon be another wildlife spectacle enjoyed by locals and visitors on St Agnes. To hear storm petrels singing magically from within the boulder beaches would be really wonderful."
Richard Bellamy, head of the Heritage Lottery Fund SW, said: "We have some wonderful native wildlife on the Isles of Scilly and collectively we have a responsibility for its survival."