Why is our native woodland in danger?

Grey squirrels damage our forests by stripping bark from trees’ main trunks (at the base and up in the canopy) and branches. Severe damage can kill a tree while milder cases involve bad scarring and substantial epicormic [1] growth. Scars left by bark stripping can also be an entry point for other tree pests and diseases – making trees more vulnerable to such threats. It is estimated that grey squirrel bark stripping damage costs the UK timber industry some £14 million per annum. Tree planted using grant funding, are also being destroyed by grey squirrels. This becomes an additional cost to the UK taxpayer.

Why are young trees most at risk?

Damage on young trees often results in tree mortality, as there is less bark to remove before the tree is ring-barked. Tree specie growing vigorously with rich phloem vessels in the bark are most vulnerable between the ages of 10 and 40 years.

What trees are damaged?

Grey squirrels target a range of trees, but their preferred species appear to be beech, field maple, oak, sycamore, hornbeam, willow and silver birch. This seriously threatens the UK’s woodland industry, as these species make up large proportions of its young woodlands in the midlands and south and southwest England. Back in 2000, a survey by the Forestry Commission of vulnerable woodlands in Great Britain estimated that 100% of sycamore, 66% of beech, 30% of oak and sweet chestnut stands had been damaged by grey squirrels. We are still suffering damage and need to keep working on landscape-scale control strategies. Thare are few tree species that are not damaged by grey squirrels. These include Cherry and Ash. Unfortunately, ash is threatened by Chalara fraxinea (ash dieback) disease which removes a species not vulnerable to grey squirrel attack. Given tree disease problems facing Ash it will become increasingly important to protect our remaining tree stock not currently affected by other pests and diseases. It is acknowledged now that conifers are also be damaged by Grey Squirrels.