Forests at risk from the grey squirrel

Ben Lennon, who helps look after the Forest of Dean in Gloucestershire, said the animals caused "enormous" damage to trees in his area after a population explosion.

An estimated 10,000 grey squirrels are active in the Forest of Dean this summer after a plentiful nut harvest last autumn and a mild winter. They strip bark off trees such as oak, sycamore and beech and this has had seriously damaging consequences, he said.

Mr Lennon, the Forestry Commission's district forester for planning, said that in some stands of woodland up to 85 per cent of the trees had been affected, with damage to more than 15 per cent of the trunk and the higher branches."In extreme cases they can kill the trees or cause them to be affected by fungus."

The Forestry Commission is spending enormous sums trying to control grey squirrels, and is looking into the possibility of contraceptive drugs, but they are probably 10 to 15 years away.