The Mammal Society

For Evidence Based Conservation

Grey Squirrel – Sciurus carolinensis

Photo by Waheed Arshad

Habitat: Urban & gardens, deciduous woodland, mixed woodland.
 
Description: Silver-grey, agouti (speckled) coat, with a brownish tinge on feet, face and along the back, especially in summer; tail fringed white. Much larger than the red squirrel, which has uniform reddish-brown (not agouti) fur.
 
Size: 24-28.5cm. Tail length: 19.5-24cm.
 
Weight: Females 0.4-0.72kg, males 0.44-0.65kg.
 
Lifespan: Females up to 5 years and males around 2-3 years.
 
Origin & Distribution: Introduced from the USA between 1876-1929 the grey squirrel is now widespread in England and Wales, central Scotland and the eastern half of Ireland – and still spreading. Grey squirrels are essentially animals of deciduous woodland.
 

Grey squirrel distribution (in green), taken from ‘Britain’s Mammals 2018: The Mammal Society’s Guide to their Population and Conservation Status.’

 
Diet: Large seeds of trees such as oak, beech, hazel, sweet chestnut and walnut. When these supplies run out in early summer grey squirrels turn to a variety of flowers, buds, shoots, pine cones, fungi, peanuts from bird feeders, birds’ eggs and young.
 
General Ecology: Squirrels are diurnal, usually with peaks of activity in the early morning and late afternoon. They are not territorial, but share home ranges and temporally abundant food sources. They typically make a nest (drey) of twigs (cut live from the tree often with the leaves attached, unlike bird nests). Dreys are usually tucked in a fork against the trunk, though squirrels also use large holes in trees as drey sites. Grey squirrels are largely animals of deciduous woodland, and are dependant upon the large seeds of such trees as oak, beech, hazel, sweet chestnut and walnut. In Autumn, when abundant, these seeds are stored, often underground. Because deciduous fruit falls to the ground in autumn, grey squirrels spend much more time foraging on the ground than red squirrels. The main predators of grey squirrels include stoats, goshawks and foxes.
 
Breeding: The female can have two litters a year in early spring and summer. Young squirrels are born blind and hairless, in litters of 3-4, after a gestation of 44 days. Lactation lasts up to 10 weeks, though the young start to take solid food after about 8 weeks. They can breed at 10-12 months old.
 
Conservation Status: Grey squirrels are serious pests of forestry, especially stripping the bark of thin-barked species such as beech and sycamore. This behaviour is not fully understood. It seems to peak in early summer, at about the time when the first litter of young become independent, and at the time when tree fruits are least available. It can kill the top of the tree or distort its growth. They can also be serious pests in gardens and among horticultural crops. It has been illegal to keep grey squirrels (without a licence) since 1937, and it is illegal to release them into the wild.
 

Identification

Silver/grey, agouti (speckled) coat, with a brownish tinge on feet, face and along the back, especially in summer. Tail fringed white. Larger than red squirrel. Can have red tinge to fur.

Field Signs
Download a printable field sign guide here!

Footprints: Tracks can be seen in mud (see photo), sand and snow.  Forefoot width is 2.5cm and length 3.5cm and hind foot width is 3.5cm and length 4.5cm.

Droppings: Droppings are usually found near trees. They can be dark grey or black and are often sweet smelling. This does depend on their diet, especially true if diet includes pine cones. They are small, round pellet shapes (0.5-0.8cm long and 0.5cm thick).

Feeding signs: Squirrels, much like birds, split nuts open at the top, leaving jagged edges and irregular pieces. They prise the nut apart after making an incision at the top. By comparison, mice and voles gnaw holes in nuts in a characteristic pattern.

Nests: The nests of red squirrel (and grey squirrel) are known as dreys. They are spherical collections (approx. 30cm across, at least 6m above the ground) of twigs and leaves which are usually located in the fork of the branches, close to the trunk. It is easier to observe these in winter when there are fewer leaves on the trees. It is not possible to distinguish between red and grey squirrel dreys.

 

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