Wildlife experts are warning that a virus is killing endangered Red Squirrels in Anglesey.
The red squirrels Wales Trust says that tests carried out on dead red squirrels on the island revealed that a lethal strain of the Adenovirus was present in 65 percent of the animals.
Newborough, Pentraeth, and Holy Island have been identified as Anglesey's hotspots for the virus.
The Trust's Project Manager, Dr Craig Shuttleworth, says infected red squirrels look perfectly normal a few days before they die, with the virus affecting their digestive systems.
The cause of the virus has yet to be identified, but mice and grey squirrels on Anglesey have also been found to have the disease.
However, Dr Shuttleworth says that there is not yet any sign the virus can be passed on to humans or domestic pets such as cats, dogs, or guinea pigs.
A threat to the species
Red squirrels were re-introduced to Anglesey 15 years ago in an effort to save the endangered species.
The island is Wales' refuge for Red Squirrels, whose numbers are threatened by the grey squirrel.
Between just 400 and 500 red squirrels remain on Anglesey, where a programme to eradicate the grey squirrel is in place.
Dr Craig Shuttleworth says the further hit to the red squirrel population posed by the virus would be substantial:
As seed dispersers who help to germinate and spread forestation, the red squirrel is a vital part of Anglesey's ecosystem.
But their value to the local community is also economic, as an attraction for tourists.
Our Correspondent Carole Green reports on the threat posed to Wales' largest single population of red squirrels by this mystery virus.