SquirrelInteresting facts and information

Squirrels are rodents in the family Sciuridae. The group includes tree squirrels, ground squirrels and flying squirrels, whose gliding differs from powered flight. Their diets, activity and winter habits vary between species.

Tree squirrels, ground squirrels and flying squirrels occupy different habitats. Some species also live in parks and gardens.

Quick facts

Common name	Squirrel
Scientific name	Sciuridae (squirrels)
Typical lifespan	Usually about 5-6 years in the wild for tree squirrels; up to about 20 years in captivity
Length	About 15-50 cm for most tree squirrels (depending on species)
Weight	About 100 g to 1.5 kg for most tree squirrels
Diet	Mainly plant food (seeds, nuts, fruit, fungi), plus some insects and eggs
Main predators	Birds of prey, foxes, snakes, wild cats, martens
Conservation status	Assessed separately by species and population; regional trends and needs differ
Distribution	Every continent except Antarctica; only introduced in Australia
Habitat	Forests, parks, grasslands, mountains

Interesting facts

Squirrels hide food in many different places to stop it being stolen - and because they do not find all of it again, they help plant new trees.
Flying squirrels glide using a membrane stretched between their limbs; this is not powered flight.
They have an excellent memory and can remember the locations of many of their food stores.
Their front teeth never stop growing, so squirrels must gnaw constantly to keep them at the right length.
They are fast and agile - Squirrels can run at up to about 30 km/h and jump many times their own body length.

Records and remarkable features

Squirrels are rodents in the family Sciuridae.

Physical characteristics and unique adaptations

Squirrels are agile, clever mammals adapted for climbing, jumping and surviving in many environments. Their bushy tails and strong legs give them balance and speed, while their strong teeth crack hard nuts and seeds.

Key physical adaptations

A long, bushy tail - Helps with balance when jumping and keeps the squirrel warm in cold weather.
Strong hind legs - Allow long leaps between branches, many times the squirrel's body length.
Sharp, curved claws - Help squirrels climb and cling to tree bark.
Ever-growing incisors - Let them gnaw through hard nut shells without wearing their teeth down completely.
Excellent all-round vision - Their large eyes on the sides of the head help them spot predators, even behind them.

Types of squirrel

Group	Features
Tree squirrels	Live in trees, are fast and have long tails for balance
Ground squirrels	Live in underground burrows, are often sturdier and more social; the group includes marmots, prairie dogs and chipmunks
Flying squirrels	Glide between trees using a furry membrane between their limbs

Habits and behaviour

Squirrels are clever and adaptable, with clever strategies for storing food, communicating and staying alive.

Way of life

Most tree and ground squirrels are active by day, especially in the morning and late afternoon; flying squirrels are active at night.
Some species defend territories or food stores from other squirrels with calls and tail movements.
Many squirrels live alone, but in cold weather several may share a nest or den for warmth.

Communication and interaction

Tail signals - Squirrels flick and wave their tails to signal alarm or annoyance.
Alarm calls - They chatter, bark and squeal to warn others of predators.
Scent marking - They leave scent by rubbing their faces on branches and other surfaces.

Survival strategies

Storing food for winter - Many squirrels bury acorns and seeds, which they can find again even under snow.
Fake caches - When they think they are being watched, some squirrels pretend to bury food to fool would-be thieves.
A good memory - They remember where many of their food stores are hidden.

Habitat and geographic distribution

Squirrels live on every continent except Antarctica and Australia, where only introduced squirrels are found. They live in many climates, from tropical forests to mountains and the Arctic tundra.

Distribution

Region	Situation	Typical habitat
North America	Many species, often very common	Forests, prairies, city parks
Europe	Red squirrels widespread; grey squirrels introduced in Britain, Ireland and Italy	Deciduous and coniferous forests
Asia	The greatest variety, including giant and flying squirrels	Mountains, jungles, plains
South America	Several tree squirrels	Tropical forests
Africa	Tree, ground and sun squirrels	Savannas, forests
Australia	No native squirrels; a small introduced population of palm squirrels	Parks in Perth

Habitats

Deciduous and coniferous forests - The preferred habitat of tree squirrels, with plenty of food and shelter.
Parks and gardens - Some species have adapted very well to life in towns.
Grasslands and dry areas - Many ground squirrels live in open country, among shrubs and grasses.

Impact of environmental change

Deforestation reduces squirrels' natural habitats.
Climate change can affect the hibernation and breeding of some species.
Competition from invasive species - The introduced American grey squirrel has replaced the native red squirrel in much of Britain.

Diet and feeding

Squirrels are opportunistic feeders: they eat mainly plant food but also take some animal protein. Their diet changes with the season and the food available.

What do squirrels eat?

Type of food	Examples
Seeds and nuts	Acorns, hazelnuts, walnuts, pine seeds
Fruit and fungi	Apples, pears, berries, mushrooms
Buds, shoots and bark	Young shoots, tree buds, bark in hard winters
Insects and other animal food	Insects, larvae, snails, bird eggs
Human food (in towns)	Bird seed, bread, peanuts (salted food is bad for them)

How they feed

They use their front paws to hold and turn nuts while they gnaw them open.
They store food in the ground or in hollow trees and remember where they hid much of it.
They adapt their diet to the season, eating more buds and insects in spring and more nuts in autumn.

Reproduction and life cycle

Squirrels breed quickly, which helps keep their populations stable even in difficult conditions.

Breeding season

Many tree squirrels breed once or twice a year, often in late winter and early summer.
Males chase females through the trees in mating chases, and the fastest, most persistent male usually wins.
A female may mate with several males in one season.

Development stages

Stage	Timing	What happens
Pregnancy	About 30-45 days	The female gives birth in a sheltered nest (drey) or tree hole
Newborns	First weeks	Born blind and hairless; depend completely on their mother
First fur and eyes open	About 3-5 weeks	They start exploring around the nest
Independence	About 8-12 weeks	They leave their mother's nest and look for their own area

Survival strategies

Females often build several nests and move their young if danger threatens.
When threatened, squirrels often freeze, then dash away in a zigzag.
Young squirrels learn to climb and jump within their first months, which helps them escape predators.

Name and history

Origin of the name

The English word "squirrel" comes, through Old French and Latin, from the Greek skiouros.
Skiouros combines skia ("shadow") and oura ("tail"), meaning "shadow-tail", because a squirrel can shade itself with its bushy tail.
The scientific name of the tree squirrel genus, Sciurus, comes from the same Greek word.

Taxonomic classification

Classification	Name
Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Order	Rodentia
Family	Sciuridae

Evolution and fossils

The earliest known squirrels lived about 36-40 million years ago, in the Eocene epoch.
Early squirrels already looked much like today's tree squirrels.
Over time, squirrels diversified into tree, ground and flying squirrels, each adapted to different habitats.

Cultural significance and mythology

Norse mythology - Ratatoskr is a squirrel who runs up and down the world tree Yggdrasil, carrying insulting messages between an eagle at the top and a dragon at the roots.
A symbol of thrift - Because squirrels store food for winter, they are seen as symbols of saving and preparing for the future.
India - In a Hindu legend, a little squirrel helped Lord Rama build a bridge to Lanka, and the stripes on the Indian palm squirrel's back are said to be the marks of Rama's fingers.

Conservation status and threats

Most squirrel species are common, but some are threatened by deforestation, climate change and introduced species.

Main threats

Deforestation and habitat loss - The loss of woodland forces squirrels into towns, where they face traffic, pets and less natural food.
Invasive species - In Britain and Italy, the introduced grey squirrel has replaced the native red squirrel in many areas, partly by spreading the squirrelpox virus.
Climate change - Higher temperatures can disrupt the hibernation and breeding of some species.
Road traffic - Many squirrels are killed by cars, especially in autumn, when they are busy gathering food.

Examples of squirrel species

Species	Status	Region
Eurasian red squirrel (Sciurus vulgaris)	Least Concern overall, but declining in Britain and Ireland	Europe and northern Asia
Indian giant squirrel (Ratufa indica)	Least Concern, but locally affected by deforestation	India
Mount Graham red squirrel (a subspecies of Tamiasciurus fremonti)	Endangered (USA)	Arizona, USA
Some island flying squirrels	Several are threatened by forest loss	Southeast Asia

Protection measures

Protecting woodland and planting new forests.
Controlling invasive grey squirrels to help native red squirrels.
Building rope bridges and green corridors so that squirrels can cross roads safely.

Squirrels in popular culture

The Tale of Squirrel Nutkin (Beatrix Potter, 1903) - A children's story about a cheeky red squirrel who loses his tail.
Scrat (Ice Age) - A prehistoric squirrel-like creature obsessed with his acorn.
Rocky the Flying Squirrel - The hero of the classic American cartoon The Rocky and Bullwinkle Show.
Sandy Cheeks (SpongeBob SquarePants) - A squirrel from Texas who lives underwater in an air-filled dome.

The squirrel as a symbol

Squirrels are popular symbols of saving money and preparing for the future, and they appear in the logos of some banks and savings schemes.

Did you know? About squirrel

There are more than 270 species of squirrel in the world, including tree squirrels, ground squirrels, chipmunks, marmots, prairie dogs and flying squirrels.
Squirrels are among the few wild animals that will take food from people's hands. Related profile: Wild animals.
The smallest squirrel is the African pygmy squirrel, which is only about 7-10 centimetres long and weighs about 10-15 grams.
The longest squirrels are the giant squirrels of Asia, such as the Indian giant squirrel, which can be about 1 metre long including the tail and weigh up to about 2 kilograms.
The heaviest members of the squirrel family are marmots, such as the Alpine marmot, which is about 50-70 cm long and can weigh about 5-8 kg.
Squirrels store nuts and seeds in many different places so that they have food during the winter.
Squirrels help new trees grow, because they bury nuts and seeds in the ground and do not dig them all up again.
When chased, squirrels run in a zigzag, which makes it harder for predators to follow them.
When a squirrel is frightened, it often freezes first.
Squirrels are clever: some pretend to bury food to fool animals that might steal it.
Like other rodents, squirrels have four front teeth that never stop growing, at a rate of about 15 cm a year, so they must gnaw constantly. Related profile: Rodents.
Squirrels breed once or twice a year and, after a pregnancy of about 3 to 6 weeks depending on the species, give birth to 2 to 8 young.
Studies have shown that California ground squirrels chew shed rattlesnake skin and lick the paste onto their fur, which may help mask their scent from snakes.
Before winter, many squirrels put on weight, and the extra fat helps them survive the cold months.
A male squirrel can smell a female that is ready to mate from a long distance.
Many tree squirrels build round nests of twigs and leaves, called dreys, high in the trees. Related profile: Birds.
Squirrels are excellent acrobats, and they can also swim when they need to, using their tail as a rudder.
In the wild, most tree squirrels live only about 5-8 years at most.
Tree squirrels eat nuts, seeds and fruit; some also eat insects, snails, bird eggs and carrion. Related profile: Omnivores. Related profile: Snail.
Their long, bushy tail helps them balance and communicate and keeps them warm in winter, like a blanket.
There are around 50 species of flying squirrel. Instead of really flying, they glide using a furry membrane stretched from their wrists to their ankles, rather like a parachute. Many glides are 20-50 metres long, and some species can glide about 90 metres.
Flying squirrels have long whiskers that help them find their way and their food in the dark.
In 2013, campgrounds in the Angeles National Forest near Los Angeles were closed for a time after a squirrel there was found to carry the plague bacterium.
Squirrels can run at about 30 km/h, but most of the time they move much more slowly.
The Arctic ground squirrel can lower its body temperature to just below 0°C while hibernating, the lowest known body temperature of any mammal.