Pesky Squirrels.

A visitor to Bicknor Wood could hardly miss the squirrels. They are the most obvious of the mammals after peoples and pooches. Despite my protestations that they are invasive and that they have displaced our native red squirrel, the grey squirrels are endearing and entertaining.

Until, that is, they start damaging the trees. They cause damage by stripping the bark either to eat the phloem or to provide construction materials for their dreys.

In the early part of the year, the bark strips will be used for building dreys which can be seen as large masses, high in the trees. The dreys are more commonly made from twigs, leaves and moss, but our squirrels have discovered a very useful resource.

During a recent storm, a drey was dislodged from on high and much of it ended up on the ground, where it became clear that they were using very finely shredded bark strips.

Later in the spring, once the kittens leave the nest, the squirrels may begin to feed on the bark. They love the sweet, sugar-carrying phloem, the tissue just beneath the surface which also carries the sap. Once a branch or trunk has lost a ring of bark, it is unable to feed itself and dies.

It is possible to recognise the dead branches caused by squirrel damage as their brown leaves still cling to them. In the normal course of events, a process called abcission (suck 'em and shed 'em) causes the leaves to fall in the autumn, but if the branch dies before this process is instigated, the stem at the base of the leaf does not disintegrate and remains attached.