First introduced in the 1870’s, the grey squirrel is now widespread across the UK, with an estimated population of 2.7 million. While they may have a sweet appearance, they carry a virus called ‘Squirrelpox’, which is fatal to our native Red squirrel, and are legally categorised as an invasive pest making release into the wild illegal.
The main impact grey squirrels have on trees is the removal of bark, known as bark stripping (see right). Beneath the bark is a layer called the cambium, which holds sugars and nutrients that the tree produces; this is a very tasty and easy treat for the squirrels, with potentially dire effects on the tree. Extensive bark stripping creates open wounds, allowing other pests and pathogens and decay fungi to damage or infect the tree; this can cause tree stunting, frailty, and ultimately death, with thousands of pounds and years of effort rapidly undone if left unchecked. Damage also affects timber quality and form (see image below).
Tree species that grey squirrel’s favour most are Oak, Beech, Sycamore, Acers and Hornbeam. Damage mainly occurs on younger trees, mostly between 10-40 years old. This is because the bark is thinner and growth more vigorous providing easy access and abundant nutrition for grey squirrels.
If you are concerned about squirrels damaging your trees, contact Nicholsons Forestry to discuss management strategies.