SQUIRRELS are driving Forest Enterprise staff nuts. The Forest of Dean is over-run with them and they are costing taxpayers tens of thousands of pounds.

Locally the problem has become so bad Forest Enterprise has virtually abandoned planting beech and sycamore – the favourites for a nibble by the thousands of grey squirrels who are happily munching the life out of trees large and small.

Experts from the Forestry Commission's research unit are now working on methods to bring a degree of control to the problem.

This year's damage is easy to see as the tops of many trees are browning, giving every indication of an early autumn but really the work of Fciurus carolinensis – the American imports having the time of their lives in the woods.

Forest Enterprise expert Mr Jim Sauter says the public perception of a furry and attractive woodland animal was far removed from reality.

"We are spending tens of thousands of pounds trying to control them. This year there has been widespread damage which we are presently trying to assess," he said.

In addition to the damage caused to the timber crop, there were other dangers such as branches killed by squirrels which overhung forest walks which had to be removed.

It was unclear, he said, why squirrels stripped bark from trees. It did not appear to be as a source of food.

"Certainly there has been much, much more damage this year. It could be that a mild winter allowed many more to survive through to the spring but there is definitely evidence of a worsening situation," said Mr Sauter.

It was generally accepted that damage was caused when the number of squirrels exceeded five or six a hectare.

The chief methods of reducing squirrel numbers were live trapping and poisoning and research experts were working on other methods including a form of birth control.

Mr Sauter said the situation in the Forest was difficult as squirrels opted to live in older trees and cause damage to younger ones.

"In the Forest we often have a mix of trees of various ages rather than plantations of trees and this makes control more difficult," he said.

Additionally, the owners of adjoining privately owned woodland also needed to take action.

"It is of little use us taking out squirrels next to a privately owned wood as we only create a vacuum which is quickly filled," said Mr Sauter.

Local legend had it that the only time the animals were completely under control in the Forest was during the 1939-45 war when US troops were stationed locally. They regarded grey squirrel as a worthwhile meal.