Squirrel damage: Call for Evidence from Woodland Owners and Managers

Creating oxygen, sequestering carbon, and supporting biodiversity - tree species are among the most important plants on the planet. Here in the UK, however, broadleaf trees are being profoundly damaged by non-native grey squirrels, at an alarming and ever-increasing rate. To help protect the country’s woodlands and to sustain important biodiversity, this week the Red Squirrel Survival Trust (RSST) is appealing to woodland owners and managers and the public to identify and report evidence of the intensive bark stripping being done by grey squirrels.

To protect the UK’s broadleaf trees, the Red Squirrel Survival Trust is seeking evidence of grey squirrels’ bark stripping damage to trees and woods.

RSST is the leading national charity established to conserve and protect the UK’s iconic red squirrel. Working alongside the UK Squirrel Accord, RSST is seeking to raise awareness of the bark stripping damage being done by invasive grey squirrels. The recent report by UKSA signatories estimates the annual cost of grey squirrel damage to trees in England and Wales to be at least £37 million. Members of the public are being asked to help by emailing photographic or video evidence of either bark stripping in progress or of the subsequent damage to info@squirrelaccord.uk. Details of any credits to be included can also be added.

Mark Henderson of RSST emphasises: “Following on from Defra’s ‘Plant Health Week’ last week, we are asking foresters and the public to get involved and share evidence with us of grey squirrel damage to trees in their area. Tackling this issue is hugely important for the longevity of beautiful woodlands and the biodiversity they support for generations to come, especially as millions more trees are planted.

“We would be very grateful to anyone who is able to share details – both now and in the future - as sadly this is not be a problem that can be solved overnight. Support from local communities is incredibly valuable and identifying bark stripping damage can be done while on woodland walks or carrying out woodland management tasks.”

Grey squirrels start by stripping a small tester patch of bark from a tree. They may then return and strip the bark from all areas of the tree to access the sap in the living tissues. To identify grey squirrel damage, look for sections of bark ripped off trees that exposes the wood beneath. Bark chippings can often be found at the base of trees with fresh damage.

Bark stripping occurs primarily between April and August, with damage to trees often being more obvious at this time of year. Vulnerable tissues are newly exposed beneath the protective outer bark, opening the tree up to infection from pests and pathogens. These wounds stress, weaken and may kill the tree, which is a serious issue for a country striving to plant more trees for wildlife, climate change mitigation, timber production and many other ecosystem benefits.

Tree species particularly susceptible to damage include high-value trees such as oak, beech, hornbeam and sweet chestnut. Grey squirrels target young broadleaved trees, mostly 10-40 years of age, and repeat the damage year after year if their densities are high and unmanaged. In addition to causing intensive woodland damage, grey squirrels threaten the survival of the UK’s native red squirrel population by carrying fatal infections and disease.