Grey Squirrels and British Woodlands

At the beginning of the summer we went to one of our walking stick  suppliers’ open days which was a really lovely day. Set in the heart of the beautiful Somerset countryside, the woodland used for coppicing walking sticks was stunning. We learnt a great deal that day about woodland management, coppicing, seasoning and straightening different types of wood for walking stick making.

But the thing I came away thinking about the most was the grey squirrels and the effect they have of our trees. I was familiar with the competition between the red squirrel and the introduced North American grey squirrel, but until this open day I was completely unaware of the serious threat the grey squirrel represents to our native woodlands.

Grey Squirrel
Grey Squirrel

The main problem for trees is that the grey squirrel likes to strip the bark of trees to get to the sugary, sap filled tissue just beneath it. Phloem tissue is the medium in which sugars are transported around the tree. The squirrel can gnaw a complete ring around the tree, thus restricting the movement of sugars around it and the tree may then die.
Even if the tree is not “ringed”, any removal of the bark or phloem tissue makes the tree more vulnerable to disease or fungal infection, thus causing the tree to rot (definitely not good for growing walking sticks!).

Interestingly, Cherry trees escape this threat as they have bark which grows horizontally around the tree which the squirrel cannot gnaw. This is because the squirrel (as he is a rodent) uses the front incisors to gnaw down the bark which is fine if the bark is growing vertically but not horizontally.

This bark stripping occurs between late April and the end of July. Very young trees or saplings (stem diameter less than 5 cm) are generally not attacked as they cannot support the weight of a squirrel, the main stem of older trees (40 years+) are usually safe as the bark is too thick for the squirrels to strip. The most vulnerable trees are sycamore, beech, oak, sweet chestnut, pine, larch and Norway spruce, aged between 10 and 40 years old; though almost any broadleaved species of tree can be attacked. Bark stripping is a problem in woodland where the squirrel numbers are greater than 5 squirrels per hectare. The risk of damage may be greatest where there are vulnerable trees next to mature woodland that produces a good seed crop, which in turn supports a high density of squirrels.

Control of squirrel numbers is difficult. Control aims to reduce tree damage by bringing the number of squirrels to below 5 per hectare.
However, it is important to remember that grey squirrels are highly mobile as a species and a non-isolated woodland can be re-colonised within a month; and even one that is isolated will have new resident squirrels within three months. Control measures should aim to ensure that the number of squirrels is at a minimum when bark stripping activity is at a maximum.

So there you have it. Growing trees for making walking sticks is not as simple as it looks or as risk-free.