Grey squirrels are accused of destroying trees. It seems utterly bizarre, since the opposite is the case: grey squirrels are some of nature’s greatest conservationists, they regenerate forests. The mechanism for this is clear enough: squirrels cache seeds and nuts, and thus plant new trees, since they usually store more than they need. Grey squirrels happen to be better at forest regeneration that red ones, since their manner of storing food, scattering rather than hoarding, is more conducive to organic forest growth. So why the accusation?
The small factual basis for the tree destruction myth is that squirrels, red and grey ones, feed on trees. They eat leaves, buds, twigs; they also strip some bark in order to get to the sap underneath. This, however, does not kill the vast majority of trees. It prunes some branches, it changes the look of the tree, but does not kill the tree. It is possible that in old fragile trees the bark stripping will make the tree vulnerable to disease and kill it. But that is a tiny proportion of them; and, in any case, if the tree falls down, becomes an important wildlife habitat in its own right, and squirrels plant new trees in its stead – it’s the circle of life.
Where squirrel chewing does cause a problem is in commercial forestry, hence the cloud of myth around the fact. But even here a sense of proportion is essential, we are talking about a small percentage of damage. According to the Forestry Commission, the damage is 5%, less than from bad growing practices, e.g. lack of thinning. Higher numbers are quoted by the Forestry Commission, but they relate to cosmetic damage to trees destined for human consumption. And in the section of the industry that produces pulp, paper, construction timer, etc., it clearly doesn’t matter. Even in the middle-range market – pine furniture, oak furniture, wooden floors – imperfections are considered part of the natural charm of the wood. Where it does matter is in the luxury market, the kind of trees that are going to be harvested in 80 years’ time. But even then, it is by no means every tree that is affected (we are talking about a fraction of a fraction of the industry); and I, for my part, hope that in 80 years’ time we will have a very different relationship with both squirrels and trees.
But, you might object, the Forestry Commission calls for the killing of grey squirrels! They have published plans and made public statements to that effect. You would, unfortunately, be right. The rhetoric of the Forestry Commission is completely at odds with their own research.* At present there seems to be no explanation for this discrepancy, other than plain incompetence on the part of Forestry Commission bureaucrats.
* Forestry Commission research showed grey squirrel damage to be statistically acceptable, just 5% (the thresh-hold for destruction being 30% of canopy trees). There is a tranche of research papers disputing this data, but this “research” constituted asking the opinions of landowners, gamekeepers and pest controllers, almost exclusively people either making money or hoping to make money out of the killing of grey squirrels. Not only was there no safeguarding against data manipulation by vested interests: in fact, most, if not all, data was collected from vested interests.