|Various members of the family Sciuridae
Fischer de Waldheim, 1817
|Subfamilies and tribes|
Squirrels are members of the family Sciuridae (/ - /,), a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squirrels are indigenous to the Americas, Eurasia, and Africa, and were introduced by humans to Australia. The earliest known fossilized squirrels date from the Eocene epoch, and among other living rodent families, the squirrels are most closely related to the mountain beaver and to the dormice.
The word squirrel, first attested in 1327, comes from the
Squirrels are generally small animals, ranging in size from the African pygmy squirrel and least pygmy squirrel at 10–14 cm (3.9–5.5 in) in total length and just 12–26 g (0.42–0.92 oz) in weight, to the Bhutan giant flying squirrel at up to 1.27 m (4 ft 2 in) in total length, and several marmot species, which can weigh 8 kg (18 lb) or more. Squirrels typically have slender bodies with very long very bushy tails and large eyes. In general, their fur is soft and silky, though much thicker in some species than others. The coat color of squirrels is highly variable between—and often even within—species.
In most squirrel species, the hind limbs are longer than the fore limbs, while all species have either four or five toes on each foot. The feet, which include an often poorly developed
Squirrels live in almost every habitat, from tropical
As their large eyes indicate, squirrels have an excellent sense of vision, which is especially important for the tree-dwelling species. Many also have a good sense of touch, with vibrissae on their limbs as well as their heads.
The teeth of sciurids follow the typical rodent pattern, with large incisors (for gnawing) that grow throughout life, and cheek teeth (for grinding) that are set back behind a wide gap, or diastema. The typical dental formula for sciurids is 22.214.171.124.
Many juvenile squirrels die in the first year of life. Adult squirrels can have a lifespan of 5 to 10 years in the wild. Some can survive 10 to 20 years in captivity.
Stated purposes of squirrels' tails, to benefit the squirrel, include:
- To keep rain, wind, or cold off itself.
- To cool off when hot, by pumping more blood through its tail.
- As a counterbalance when jumping about in trees.
- As a parachute when jumping.
- To signal with.
The hairs from squirrel tails are prized in
When the squirrel sits upright, its tail folded up its back may stop predators looking from behind from seeing the characteristic shape of a small mammal.
Squirrel in sunlight
Squirrel in Chandigarh
Squirrel near Chandigarh
Squirrel onmango tree
Squirrels mate either once or twice a year and, following a
Ground squirrels and tree squirrels are usually either
Squirrels, like other rodents, employ species-specific strategies to store food, buffering against periods of scarcity.
Because squirrels cannot digest
Aggression and predatory behavior has been observed in various species of ground squirrels, in particular the thirteen-lined ground squirrel. For example, Bernard Bailey, a scientist in the 1920s, observed a thirteen-lined ground squirrel preying upon a young chicken. Wistrand reported seeing this same species eating a freshly killed snake. There has also been at least one report of squirrels preying on atypical animals, such as an incident in 2005 where a pack of black squirrels killed and ate a large stray dog in Lazo, Russia. Squirrel attacks on humans are exceedingly rare, but do occur.
Whitaker examined the stomachs of 139 thirteen-lined ground squirrels and found bird flesh in four of the specimens and the remains of a short-tailed
The living squirrels are divided into five
A variety of fossil squirrels, from the latest
Apart from these sometimes little-known fossil forms, the
The main group of squirrels can be split into five subfamilies. The
- Subfamily Cedromurinae (fossil)
- Subfamily Ratufinae– Oriental giant squirrels (1 genus, 4 species)
- Subfamily monotypic)
- Subfamily Sciurinae
- Tribe Sciurini – tree squirrels (5 genera, about 38 species)
- Tribe Pteromyini– true flying squirrels (15 genera, about 45 species)
- Subfamily Callosciurinae – Asian ornate squirrels
- Tribe Callosciurini (13 genera, nearly 60 species)
- Tribe Funambulinipalm squirrels (1 genus, 5 species)
- Subfamily Xerinae – terrestrial squirrels
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Squirrels have been kept as pets in Western society at least until the 19th century. Because of their small size and tame nature, they were especially popular with women and the clergy.
Squirrels are a cause for concern because they often cause electrical disruptions. It has been hypothesized that the threat to the internet, infrastructure and services posed by squirrels may exceed that posed by cyber-attacks.
Squirrels have been reported to be "successfully trained" in
- American red squirrel
- Animal track
- Black squirrel
- Eastern gray squirrel
- Fox squirrel
- List of animal names#squirrel
- Red squirrel
- Squirrel relationship with humans
- Variant Creutzfeldt–Jakob disease (Kuru) from eating squirrel brains.
- Western gray squirrel
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