Urban Wildlife - Grey Squirrel

Grey squirrel (Sciurus carolinensis) © Debs Pearson

Fascinating Fact about Grey Squirrel

The grey squirrel is a very familiar animal in the United Kingdom, despite not being native. It was introduced from North America during the late 19th Century and since then has displaced the native red squirrel across most of England and Wales, though not Scotland and Ireland.

All about Grey Squirrel

What to look for

As its name suggests, this squirrel typically has a grey coat with white undersides, though the coat colour can also be quite brown. It is up to 30cm long with a bushy tail almost as long as the body. The hind legs are bigger and more powerful than the front legs.

When and where to see

The grey squirrel can be found in a wide range of habitats, including deciduous, mixed deciduous/coniferous woodland, suburban parks and domestic gardens. It is active during the day, spending most of its time in the trees, but often coming down to the ground to search for food. It is a superb climber, moving rapidly through the trees and leaping between them with ease. It is one of the few mammals which can climb head fi rst down a tree.
Grey squirrels do not hibernate, so may be seen at all times of the year. However, in winter they are far less active, sleeping for long periods, sometimes several days at a time, and they are less frequently spotted during this season.

Did you know?

  • Grey squirrels are mainly herbivorous, eating acorns, hazel nuts, berries, fungi, buds and shoots, and even bark. However, on rare occasions when plant food is very scarce they will eat insects, smaller rodents, bird eggs and nestlings.
  • Grey squirrels breed twice a year, December to February and May to June. The fi rst litter of 2-6 pups is born in February to March, the second in June to July. The gestation period is about 44 days. The young are weaned at 7 weeks and leave the nest after 10 weeks.
  • Grey squirrels build a large, untidy looking nest (drey), in the treetops or hollow tree trunks. The drey is usually lined with moss, thistledown, dried grass, and feathers.
  • Squirrels collect nuts and seeds in the autumn and bury them in many scattered hiding places or caches around the wood. They have a highly-developed spatial memory and acute sense of smell, which aid them in finding the caches even weeks or months later. Even so, many caches remain uneaten each year allowing the seeds and nuts to grow, so helping to disperse the tree’s seeds through the woodland.
  • The introduced grey squirrel has been so successful in displacing its native cousin partly because it is bigger and stronger, able to find more food and store more fat in its body for winter. This allows it to out-compete the red squirrel, which has lower survival and breeding rates. A second reason is the Para-poxvirus, which causes a fatal infection in red squirrels. Grey squirrels are not affected, but act as carriers, spreading the virus to red squirrels in the vicinity.

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