The following information comes from The Woodland Trust and the Animal & Plant Health Agency (APHA).
Estimates of grey and red squirrels numbers in the UK from 2018:
- Grey squirrels: 2.5 million
- Red squirrels: 140,000
> Grey squirrels were first introduced to the UK in the 19th century. The species has spread rapidly and is now common across the UK, with the exception of north and western Scotland and some islands.
> The introduction of grey squirrels has had a disastrous impact on the UK’s only native squirrel species, the red squirrel. Greys compete with reds for food and also carry a virus known as squirrelpox. While greys are actually immune to the disease, they transmit it to reds, for whom it is fatal. The UK’s only viable populations of red squirrels are in places where greys are rare or absent.
> Grey squirrels can also affect the composition of native woodland by bark stripping and eating the seeds of certain trees. In parts of the country, the species is culled to protect red squirrels and mitigate its damaging impact.
> Fertility control has been proposed as a humane, publicly acceptable and cost-effective method for reducing populations of grey squirrel.