Biggest threat to the National Forest – grey squirrels

Grey squirrel bark stripping damage by National Forest

Grey squirrel bark stripping threatens trees and all the hard work people have put in to grow the National Forest over the last 25 years. The National Forest Company is working to develop a landscape-scale approach to managing grey squirrels to protect woodland.

The National Forest is a 200 square mile area of the Midlands that has been the focus of mixed, native woodland planting for the last 25 years. Much of the land was restored from mining, quarrying and landfill. Therefore, the quality of soil suited the planting of trees, which will help the land recover over time. Forest cover is now at 21%, which is twice the national average, but it started at a low 6%. As positive as this is in many ways, it also equates to over 10,000 hectares of trees vulnerable to grey squirrel damage.

The National Forest and its grey squirrel problem

As much of the National Forest is less than 25 years old, many of these young trees are susceptible to bark stripping by grey squirrels. The reasons for this damaging behaviour are not clear, but It is thought they strip the bark of broadleaf trees 10-40 years old to access nutrients or as a behavioural trait through their adolescent period. Damage is worse when the population density is high.

When a squirrel strips tree bark it removes the tree’s protective layer, stressing the tree and opening it up to infection. If stripping is extensive, it can weaken stems so much they snap off and can even kill the tree. Even when the tree survives the timber value of the tree is affected. This is either through staining from infections or the loss of straight form, which makes the trees less desirable to send through a saw mill. It could reduce the value of an oak tree from around £220/m3 at roadside for high quality planking grade to £38/m3 for low grade firewood - less than 20% of its potential value before it was damaged by grey squirrels. This is causing a major issue for people who want to plant productive biodiverse broadleaf species.

In small quantities, an increase in standing deadwood from bark stripping could be beneficial to a woodland ecosystem, along with forgotten food caches which can result in squirrel-planted saplings. However, if extensive damage occurs across a whole woodland it can be unsustainable.

Grey squirrel bark stripping damage by National Forest

Solutions and support for landowners

As with many forms of land management, a landscape-scale approach is the only way to effectively reduce grey squirrel numbers to minimise damage. If only a few woodland owners undertake control measures it creates a vacuum in those woods, which are annually repopulated by the young (that are more likely to bark strip) from neighbouring woods that lack active management.

Several methods are being promoted by the National Forest Company to drive a landscape-scale approach to squirrel control; grant-funded trapping, air rifle shooting in conjunction with the British Association of Shooting and Conservation (BASC) and educating landowners of the problems grey squirrel damage cause, which they may be unaware of.

The National Forest Company provides grants for the purchase of traps and the time needed to check them through a Woodland Management Grant. This incentivises landowners and managers to undertake control measures and reduces any economic obstacles.

Working with BASC, a programme was developed to link their members with landowners that need to manage grey squirrels to protect their woods. Members must complete a competency course to ensure they can safely use an air rifle to humanly dispatch a grey squirrel. There is little to no cost for the landowner and the BASC members are able to use their hobby to help protect local woodlands.

The National Forest raises awareness of the issue of grey squirrel bark stripping through site visits to show landowners and managers the severity of the damage taking place. Events and forums are held to spread the grey squirrel damage message, along with other woodland management topics. New approaches to squirrel management are also trialled to understand and spread good practice.

As a signatory to the UK Squirrel Accord, the National Forest supports their research into an oral contraceptive that may offer another humane option for grey squirrel management. Involvement in various partnerships such as this show the National Forest’s commitment to protecting our woods and encouraging the return of red squirrels across the whole of the UK.

The Future of the National Forest

The National Forest’s long-term aim is to increase forest cover to 33% with a mixture of productive, amenity and wildlife woodland growing in a populated area of lowland England that also supports agriculture.

If grey squirrel damage can be managed, landowners are able to grow woodland that can produce quality timber, people can access the woods without increased risk of tree branches snapping out overhead and wildlife will be able to thrive in a more balanced ecosystem. A widespread landscape-scale approach to grey squirrel management is key to achieving this and the National Forest is working hard to make it a reality.

To find more information on the National Forest, the National Forest Company or to make a charitable donation, please visit The National Forest’s grey squirrel activity and impact assessment methodology and recording sheet can be found in the UKSA resources library.

Dan SmallDan Small is Woodland Management Officer for the National Forest Company and Chair of the UK Squirrel Accord Knowledge Exchange and Woodland Management Subcommittee. He promotes the benefits of managing woodland across the 200 square miles of the National Forest.