UK broadleaf trees are being 'profoundly damaged' by non-native grey squirrels, at an alarming and ever-increasing rate.

So says the Red Squirrel Survival Trust, which has appealed to woodland owners and managers and the public for evidence of grey squirrels’ bark stripping activities as part of its campaign to highlight the problem.

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 Details of any credits to be included can also be added.

Mark Henderson of RSST said: “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 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.

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.