The campaign against the rats cost �500,000

The mammals were blamed for eating the eggs of shags, razorbills and Manx shearwaters on Canna.

The National Trust for Scotland (NTS) said the pest control had led to an increase in birds.

Rare wood mice, taken off Canna to protect them from the poisoned baits used, have been returned to the island.

The last known rat was detected and poisoned in mid-February.

NTS said monitoring by wild bird organisation, Highland Ringing Group, has shown key species to be increasing in numbers.

Razorbills, which nest amongst boulders, have gone from 27 successful nests in 2005 to 273 in 2006.

Tape recordings

A colony of shags have increased from 48 pairs last year to 72 pairs in 2006.

Canna was once home to the one of the largest colonies of shags in Europe but the numbers had declined by over 40%.

Manx shearwaters had been wiped out from a colony previously estimated at 1500 pairs leaving one pair in a remote location in 2002.

The use of tape recordings of shearwater calls has revealed that birds have returned to the some of the burrows in the former colony.