Conservation charity the European Squirrel Initiative (ESI) is warning of the potential of an intensity in tree damage caused by grey squirrels, following on from a bumper crop of tree seed production, providing more food to support increased populations of the invasive, non-native species.
With all evidence suggesting 2025 to be a ‘mast’ year, when certain tree species, including oaks, beeches, hazels and chestnuts produce a much larger crop of fruits, nuts or seeds than normal, fears are being raised that this will lead to significant grey squirrel population increases, in turn leading to increased incidences of significant tree damage.
“With an abundant supply of seeds and nuts, we can expect better grey squirrel survival rates through winter, and more resources for breeding, so inevitably populations will increase,” explained ESI vice-chairman and chartered forester, Charles Dutton.
“The upshot of this, is that when grey squirrels increase in numbers, so we see more damage to trees, particularly by bark stripping. That bark-stripping primarily occurs between April and October, at a point when we can expect these bumper populations to be active,” he adds.
Young broadleaved trees, between 10-40 years old, are particularly vulnerable, especially species like oak, beech, hornbeam and sweet chestnut.
“In the coming year, we should be alert to the heightened risks of tree damage as the pressure on saplings and young trees increases. Woodland managers need to be aware that the boom of mast, will likely mean a boom of grey squirrel damage risk too,” continued Mr Dutton.
“With the Royal Forestry Society stating in 2021 that grey squirrels will cost England and Wales forestry at least £1.1 billion over the next 40 years in damaged timber, lost carbon revenue and tree replacement, this is an added burden to those dire projections,” he added.
As well as damaging trees, parks and gardens and predating on woodland birds, grey squirrels have driven our native red squirrels to the verge of extinction, both through competition and as carriers of the squirrel-pox virus to which greys are immune.
The ESI is seeking the restoration of the native red squirrel and the protection of the natural environment by removing the impact of the alien grey squirrel in Europe. The charity believes that by embracing gene editing tools, grey squirrel populations could be suppressed.
“ESI has funded research, through the Roslin Institute, into species-specific, humane and cost-effective solutions to managing invasive grey squirrel populations, by spreading female infertility genes through targeted populations. This in time would lead to population decline, owing to the lack of fertile female squirrels available as breeding partners,” explained Mr Dutton.
“By using gene editing to harness natural genetic resources, we believe further research can lead to a humane solution to the problem of grey squirrels, as well as other invasive, non-native species, while also being of huge economic and environmental benefit for our country,” he concluded.
