Grey Squirrels in the UK: A Growing Problem
Grey squirrels (Sciurus carolinensis) were first introduced to Great Britain from North America in the late 1800s. Since then, their population has exploded, with estimates suggesting there are now over 2.5 million grey squirrels across the UK. Their rapid spread has had a devastating effect on native ecosystems—most notably driving the decline of the native red squirrel through competition for food, habitat, and the transmission of squirrelpox virus, which grey squirrels carry but are immune to.
Breeding and Population Growth
Grey squirrels are prolific breeders. They typically produce two litters per year, with each litter consisting of 3 to 5 young. Breeding usually begins in late winter (January–February), with a second cycle in the summer (June–July). With favourable conditions and abundant food sources, populations can increase quickly and become difficult to manage without intervention.
Environmental and Economic Damage
Grey squirrels cause extensive damage to the UK’s woodlands and rural properties. Their most destructive behaviour is bark stripping, where they peel bark from young trees—particularly oak, beech, and sycamore—to feed on sap. This weakens or even kills trees, leading to significant losses in both commercial forestry and conservation areas.
Other forms of damage include:
Raiding bird nests, reducing native songbird populations.
Digging up bulbs and damaging garden plants.
Gnawing into loft spaces, cables, and insulation when they invade homes or outbuildings.
The economic cost of grey squirrel damage is estimated to be millions of pounds each year, particularly in forestry and conservation management.