There are 2 types of squirrel in these Isles - the red squirrel (Sciurus vulgaris) which is native and the grey squirrel (Sciurus carolinensis) which was introduced from North America to parks in the late 1800s.

The red squirrel has characteristically ginger, red or dark brown hair and ear tufts. It measures 35-45cm including its tail and weighs 220-350g. The grey squirrel is grey with a red tinge that varies throughout the year and has no ear tufts. It measures 45-55 including its tail and weighs 450-650g.

As grey squirrels have thrived, red squirrels have declined in number, possibly due to competition for food. Importing exotic species, however cute, runs the risk of harming native wildlife.

If squirrels nest in your loft they can chew cables so it is wise to evict them before the young are born and to block the entrance once you are sure no young will be trapped.

It is debatable whether grey squirrels should be encouraged as they are non-native. However, they are here to stay regardless. In 1953 free cartridges were offered and a bounty placed on grey squirrel’s heads of one shilling and later two shillings per squirrel to try to eradicate them. Five years and £100,000 later the scheme was abandoned as a failure. Most mortalities are in summer when last year's food stores of buried nuts are gone and few foods are available.

Some people feed them peanuts (often unwittingly as they 'steal' them from bird feeders). Avoid offering salted nuts. Nut-only diets can cause brittle bones. A mix of peanuts, pine nuts, sunflower seeds, carrots, apples and maize should be placed high up. Fish, and honey are also desirable.

Red squirrels are not common in gardens so it is better to focus on habitat preservation, particularly in coniferous forests where they do well. Avoid frustration - prevent gnawing by using tree guards, and by using squirrel-resistant or squirrel-proof feeders.

Plant native trees. A mini woodland will help all sorts of garden wildlife.

They eat a varied, mostly vegetarian diet of tree seeds, berries, fruit, nuts (especially acorns, hazel nuts and pine nuts), buds, young shoots, flowers, the tissue underneath bark and fungi but also insects, bird’s eggs and nestlings. Food that will last such as nuts is buried in the ground and recovered during times of limited food supply, particularly in winter, using a well-developed sense of smell. Seeds that are not recovered will germinate, making squirrels a valuable seed dispersal mechanism for trees.

Squirrel's build nests called 'dreys' in the fork or hollow of a tree or disused crow's nest. They are made of twigs and lined with soft hair, leaves, moss and dry grass. The drey has a domed roof and unusually for a nest, access is from the underside. It is sometimes shared and can last a few years. The young ('kittens') are raised here

Squirrels don't hibernate although in bad weather they sleep for days in their dreys without eating.

Only the pine marten is a significant predator in trees but domestic cats are often a nuisance and a fox or bird of prey may take an unwary one.

Grey squirrel: widespread in lowland Britain and Ireland. Red squirrel: widespread in Scotland and Ireland, scattered in England and Wales.

Red squirrels live for 5-10 years and greys for 8-9 years. It is illegal to kill, trap or keep a red squirrel.

When essential, a squirrel will swim 'doggy style' using its tail as a rudder.

Don't risk hand feed squirrels as they have eyes at the side of their heads and can misjudge and accidentally bite you with their very sharp teeth. They also have very sharp claws so letting them run up you is a rather uncomfortable experience!