A colony of seabirds is at risk amid fears mice have returned to a remote island.

       Conservationists on St Agnes in the Isles of Scilly have been alarmed by the potential impact of the rodents on its nationally significant population of storm petrels.

       The island, which lies 28 miles off the British mainland, was declared free of mice and rats in 2016 following an eradication programme.

       But the Isles of Scilly Wildlife Trust has now said they have seen likely signs of a mouse, including droppings and urine, raising fears that the rodent may have arrived contained in animal feed.

       Tony Whitehead from the Royal Society for the Protection of Birds warned that if mice were to return to the island they could eat the eggs of birds such as storm petrels and Manx shearwaters, putting populations at risk.

       Manx shearwaters and European storm petrels are amber-listed under the United Kingdom Birds of Conservation Concern.

       Populations of the species began to bounce back after the eradication of mice and rats, following a quarter of a century of year-on-year declines, while rodents are believed to have arrived on the island in the 18th century on shipwrecks.

       Mr Whitehead said a member of the community had spotted the mouse droppings last Thursday.

       “The residents of the island have been brilliant and hugely supportive,” he said.

       The wildlife trust said signs had been put up across St Agnes to warn parents with young children and dog owners about mouse traps.

       A similar project of rat clearance was started on the nearby island of St Helen’s earlier this year, prompting warnings for residents not to take their dogs when visiting.

       The wildlife trust said it would act as a pilot project to trial and develop techniques and materials to be used in potential future eradication projects, which would include Bryher, St Martin’s, Tresco and uninhabited islands.