THE THREAT
The grey squirrel (Sciurus carolinensis) is the principal threat to the survival of the red squirrel in Britain. The grey squirrel has already:
- Driven out the British red squirrel (Sciurus vulgaris L) from all but a few "last outposts" on the mainland
- Caused irreparable damage to coniferous and broadleaved trees such as beech, oak, sycamore and Norway spruce.
- Degraded timber quality;
- Raided birds’ nests to prey on eggs and fledglings;
- Deprived native British wildlife of food both in the wild and in gardens;
- Damaged orchards and gardens;
- Damaged historic and ancient woodlands and forests;
- Invaded and caused damage to domestic and commercial premises;
- Gnawed through electrical cables;
- Is now posing a serious threat to the great forests of northern Italy, France, Switzerland and Germany.
The grey squirrel was introduced to England, Scotland and Ireland from North America in the Victorian era. It has colonised 90% of England and Wales and has expanded from its introduction sites in Scotland.
In Britain, it has few natural predators. It has successfully adapted to British lowland conditions. It is omnivorous, breeds strongly and is an aggressive settler equally at home in urban parks and the countryside.
Grey squirrels are vectors of the squirrelpox virus for which no vaccine is presently available and which is deadly to red squirrels but does not seem to affect the host. This research is cited as a "useful example of how diseases carried by invading species can act as biological weapons and speed up their conquest of native species.”
Grey squirrel debarking pole sycamore (OSF)
Red squirrel infected with squirrelpox virus (Sarah Mcneil)
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