It is a sobering fact that as a society we need to drop our net carbon emissions to zero. That means reducing our carbon footprint as much as we can, then for what we cannot avoid, finding ways to capture carbon and keep it there for the long term. Only in this way will the UK and the rest of the world achieve net zero carbon by 2050. Ian Danby discusses what all this has to do with squirrels…
Grey squirrels are an invasive alien species in the UK. Greys out-compete native red squirrels for food and carry the parapoxvirus – or squirrel pox virus, leading to the decimation of red numbers. Grey squirrels can also have a significant impact on our environment; here’s a bit of background.
A key element in the quest for carbon capture and storage is increasing woodland cover, both through natural regeneration and planting.
Trees take in carbon, both from the soil in the form of nutrients and from the air in the form of carbon dioxide (CO2). The plant uses this carbon along with water to make sugars through photosynthesis, releasing that handy by-product, oxygen.
Trees which are harvested for use, say, in home construction or to make furniture, leads to that carbon staying locked up inside the wood for decades. Research has also shown that soils themselves usually increase their stores of carbon in woodland areas as the leaf and branch litter accumulates. But what about squirrels? Ok, I’m getting to that bit…
Planting trees or allowing woodlands to extend through natural regeneration is a land management choice, and shooting is a known reason why landowners choose to do it.
Now, let’s assume that through government funding schemes, and motivators like game shooting, we are going to get enough trees in the ground to mitigate carbon we cannot avoid emitting. Job done? Not quite. Trees are vulnerable to diseases and direct herbivore damage. In this case, squirrels.
Grey squirrel can damage trees up to 35 years old through bark stripping. This can kill the tree directly, or make it vulnerable to disease which may also kill it. It can inhibit the growth of the tree to such an extent that it loses value for carbon storage, biodiversity or the forester.
A 2021 report by the Royal Forestry Society analysed the cost of grey squirrel damage to woodlands in England and Wales. It estimated that within the next 40 years, at least £1.1 billion could be lost in timber and carbon capture due to damage caused by them.
Obviously shooting is one of the control methods available to the forester, landowner or others to help deal with grey squirrels. And it can be very effective, but requires significant investment in terms of time and effort needed.
Kill traps are used where no red squirrels are around. Live capture traps are used in areas where the reds are present, so the grey squirrels can be humanely despatched, and the reds released unharmed.
BASC has worked in partnership with many governmental and non-governmental conservation organisations on grey squirrel management. We also offer training and guidance on best practice for anyone wanting to control the greys.
However, despite these combined efforts, and some notable successes for red squirrel conservation, the grey squirrel population is still thriving.
Additional management tools are being developed and are much needed. The UK Squirrel Accord, for which BASC is one of the signatories, is leading the development of an immuno-contraceptive for grey squirrels.
The contraceptive will be delivered through feed hoppers designed to be accessible by grey squirrels only.
We hope this will reduce the grey squirrel population enough to minimise their bark stripping habits and the damage it causes to trees.
Next step, combine the contraception method with the existing control techniques like shooting, trapping, as well as the positive impact pine martens have in discouraging grey squirrels. The resulting benefits for woodland carbon capture and storage, as well as overall tree health and biodiversity, would be even greater.
Both BASC and our members have contributed towards research into grey squirrel contraception and a report of some of the fieldwork we took part in with the Animal and Plant Health Agency (APHA) can be read in an excellent book, Saving the Red Squirrel – Landscape-Scale Recovery. You can also check out this article by Sarah Beatham if you like well-written science.
The most recent update on the progress of the immuno-contraception results can also be read on the UK Squirrel Accord website.
Shooting sports are maligned by some, either through ignorance or devilment.
However, those that take the time to understand the values that people who shoot hold can see we are an integral part of helping the UK meet its net zero carbon emissions by 2050. That may be by working in partnership with landowners, foresters, or overarching conservation agencies, with all eyes turned towards finding new and better ways to manage grey squirrels for environmental benefit.