Grey squirrels are an alien species and were introduced to the UK from the USA in the late nineteenth/early twentieth century. Their success has been to the detriment of our native red squirrels.

Life span
Up to 9 years.

Statistics
Head and body length: 23-30 cm, Tail length: 19-25cm, Weight (adult): 400-600g.

Physical description
Grey squirrels are distinguished from red squirrels by their grey fur, smaller ear tufts and their larger, more robust build. Grey squirrels sit with their large bushy tail arched over the back.

Distribution
They are widespread throughout England and Wales, south of Cumbria, and are common in local pockets in Scotland. They are absent from the rest of mainland Europe, except for small localised populations in Italy.

Habitat
Common in deciduous and mixed woodland, they are also found in hedgerows, trees, parks and gardens.

Diet
Grey squirrels feed on acorns, tree shoots, flowers, nuts, fruits, roots and cereals. They bury surplus food 2-5cm below the soil or in tree hollows. They feed at ground level, more so than red squirrels, and together with their ability to digest acorns, (which reds can't), they have tended to displace red squirrels in areas of woodland where the two have come into contact.

Behaviour
Grey squirrels live in a compact, spherical nest (drey), 30-60cm in diameter, with an outer frame of twigs, and dry leaves and grass inside. They are diurnal, active from before sunrise to after sunset. The peak of activity is in the autumn. Their range covers 2-10 hectares.

Reproduction
Females produce a litter of usually three young in the spring or late summer (or occasionally both), after a gestation period of 42-45 days. The young are weaned after 10 weeks and are independent at 16 weeks.

Conservation status
Grey squirrels are widespread and not protected in the UK. They are considered a pest of forestry, and are often killed on roads.