SEA BIRDS are set to return to a Scottish island after a two-year operation to end a devastating rat invasion.
After a combined effort by Glasgow University's zoology department and Rentokil, Ailsa Craig in the Firth of Clyde is thought to be rat-free for the first time in 100 years.
Now scientists hope puffins, which nested in their hundreds of thousands before the rodents became established, and other burrow-nesting sea birds will be able to recolonise the island.
Bernard Zonfrillo, one of the university's researchers, said yesterday that the rats had spread rapidly after coming ashore from a wrecked ship, eating the eggs and chicks of sea birds.
Exterminating the invaders involved placing five tons of warfarin poison-bait, flown to the island by helicopter, in burrows during the winter when rat populations were at their lowest.
'It seems to have worked as there is no longer any evidence of rats,' Mr Zonfrillo said. 'Plants which were also eaten by them are already recovering and we are looking forward to the puffins and other birds returning.'
The project had attracted international interest and similar operations on other islands could follow.