Grey Squirrels are generally grey in colour with patches of redder fur on their feet and face. Squirrels are not native to the UK and have pushed our native Red Squirrel to only a few isolated pockets.
As Squirrels are a member of the rodent family their incisors are constantly growing; to keep them in tip top condition, they gnaw. Damage from gnawing is the main consequence, they are known for eating eggs of wild birds, gnawing and ring barking trees causing them to die, gnawing through electric wiring, water & gas pipes as such sometimes causing fires, floods and explosions.
The insurance industry estimates 25% of house fires are caused by rodents.
The first sign of problems other than seeing them in your garden is normally hearing something in your loft; this can be sounds of scurrying around to loud footsteps.
