Information about Squirrels

squirrels sciuridae information about

Squirrels are medium-sized rodents that belong to the family Sciuridae. The word “squirrel” seems to be derived, at its very beginnings, from the Ancient Greek “skiouros”, which can be literally translated as “shadow-tailed”, a reference to the bushy tailed possessed by many species of squirrels. Squirrels are closely related to the other members of the family Sciuridae, namely chipmunks, marmots, flying squirrels, and prairie dogs.
They are divided into 5 subfamilies, with 58 genera, and around 285 species, 3 main “types” of squirrel:

  • ground-dwelling;
  • tree-dwelling;
  • flying squirrels.

The earliest squirrels date from the Eocene period, and seem to actually be more closely related to mountain beavers than to any of the current members of the family Sciuridae.

squirrels sciuridae information about

Description and distribution

All squirrels have a slender body, 2 pairs of legs, and a bushy tail. Legs end in paws, each with 4-5 toes, including an (often poorly developed) thumb. Claws are sturdy and perfectly adapted to grasping and climbing. Generally, their hind limbs are longer than their fore limbs. Interestingly, tree squirrels can rotate their ankles to 180 degrees, so that their hind paws point backwards; this gives their claws the possibility to grip the tree bark better, which in turn allows the squirrels to descend a tree head-first. Squirrels are also capable of jumping up to 6m, and of running up to 32kph.
It should be noted that flying squirrels are not able to fly, per se, but actually glide with the help of a membrane which stretches from their wrists to ankles. In some species, this membrane can reach up to 45m, and they can glide up to 48m.
Squirrels have large eyes and excellent vision, which is particularly important in the case of tree squirrels. They also have whiskers (also called vibrissae) on their heads and their limbs, which gives them a relatively good sense of touch. Teeth are typical similar to those of rodents: 4 large, gnawing incisors that continue growing all throughout life and grinding teeth set behind a wide gap, known as a diastema.

Squirrels are small animals, though actual size will depend on the species. For example, the African pygmy squirrel (Myosciurus pumilio) will measure around 7-10cm in length and weigh around 10g, while the Indian giant squirrel and the Laotian giant flying squirrel (Biswamoyopterus laoensis) can both measure up to around 1m and weigh up to around 1,8kg. Grey squirrels, the most common species in North America, are medium-sized squirrels, growing around 38-50cm in length, plus tails of around 15-24cm, and weighing around 0,45-0,68kg.
Fur characteristics will vary heavily according to the species. Colouring ranges from brown, to red, and even black, and is highly variable even within species, depending, for instance, along with the thickness of a squirrel’s fur, on the seasons. However, one thing all species will have in common is that a healthy specimen’s fur will almost always be soft and silky.

Squirrels are indigenous to the Americas, to Eurasia, and to Africa, thus living on every continent, with the exception of Australia and Antarctica. They are adapted to life in nearly every habitat on Earth, from tropical rainforests to semiarid deserts; the only exceptions are the high polar regions and the extremely dry deserts.
Both ground- and tree-dwelling squirrels are either diurnal or crepuscular; flying squirrels, on the other hand, tend to be nocturnal. During winter, some species of squirrels will hibernate. While ground-dwelling species are generally social animals, often living in well-developed colonies, the tree-dwelling species are known to be more solitary. A group of squirrels will be called a scurry or a dray.
Tree-dwelling squirrels will build nests high up in trees; these will be roughly the size of a football, made out of twigs and lined with grass, moss, and feathers for comfort and insulation. Ground squirrels, on the other hand, dig entire systems of lived-in tunnels underground. Flying squirrels live in pre-existing tree holes or build nests in the crooks of branches.
Squirrels communicate using 2 main channels: various vocalizations and scent markings. Strictly between themselves, they will use tails as signalling devices. For example, they will twitch it to alert others of possible dangers. Despite their relatively small size and social nature, squirrels are extremely territorial, known to fight to death in order to defend what they consider to be their area.

Breeding and dietary information

Depending on the species, squirrels will breed once or twice a year; following a gestation period of around 3-6 weeks (with smaller squirrels having shorter gestation periods), they will have a variable number of younglings (usually 2-8). These are called kits or kittens; they are born blind, toothless, and naked, and thus completely dependent on the mothers. In most species, the female will take care of the younglings, alone. They have a strong maternal instinct and are vicious when it comes to defending their babies. They are weaned at around 6-10 weeks, but when they leave the nest, they generally do not travel farther than 3km. Young squirrels become sexually active at the end of their first year of life.
Because they are small and relatively defenceless, there are a lot of animals that squirrels need to be wary of, including domestic cats and dogs. Their primary defence method involves motionlessness, when a threat is first detected, followed by running; if the squirrel is on the ground, it will run to a tree and climb to safety, whereas if it is already in a tree, it will press itself against the bark in search of camouflage and protection. Interestingly, part of the reason why squirrels tend to run in erratic, almost zig-zag patterns, is to confuse potential predators as to what direction they may be trying to escape in. Sometimes, groups of squirrels may collaborate, using a whistling call to warn each other of approaching danger. Adult squirrels can have a general lifespan of 5-10 years in the wild, and 10-20 in captivity. The truth, however, is that most squirrels die in the first year of life.

Squirrels are unable to digest cellulose; instead, they rely on protein, carbohydrates, and fats to survive. On average, an adult squirrel will eat around 0,45kg of food each week. They are primarily herbivorous, feeding on a wide variety of plants, such as: conifer cones, fruits, fungi, generally green vegetation, nuts, and seeds. To some species, tree sap is a delicacy.
Most species that are adapted to life in cold regions have learned to plan ahead in order to survive during the wintertime. As such, they store nuts and seeds in various locations (most commonly buried underground), and return to them throughout the cold months, when food is scarce. Because they bury so many nuts and seeds and sometimes forget where they put them, squirrels are considered by many to be great at planting trees. Interestingly, but perhaps not surprisingly, squirrels go to great lengths to hide the location of these food supplies. One example is that they will hold bogus food burying displays, tricking onlookers (i.e. potential thieves, such as birds or other squirrels) and allowing them to truly hide the food someplace else, at a distance from prying eyes. The early spring, however, is the hardest time of the year for squirrels, seeing as it is when buried nuts begin to sprout; unable to consume them, squirrels are more likely to feed on the buds of the trees.
Some species of squirrels have been known to display carnivorous behaviour, especially when faced with hunger. In such situations, they eat eggs, caterpillars, insects, small birds, young snakes, and even small rodents.

Squirrels as pests

Although they do not infest homes in large numbers and are considered by many to be cute, squirrels are also found to be much more invasive than any other type of pests, mainly because of the range of damage they can cause. Your garden, your house, and even your vehicles are not safe from them. They will chew anything they can (plastic and metal included), they can bite on electric cables, cause blackouts and even fires; they will bury food in your garden, only to then dig hundreds of holes in an effort to find it. What’s more, because of the familiarity they have in dealing with people and because of the easy way in which they can adapt to every situation, squirrels cannot be easily scared, so even owning a pet can no longer be considered an insurance against a squirrel infestation. For this reason, it is safe to say that many people will never be rid of squirrels; all you can do is therefore to try your best to limit their access to places where they can cause the most damage.
One of the easiest ways that you can avoid running into problems with squirrels is by keeping in mind that, if you voluntarily feed them, these small rodents are very likely to take that as an open invitation to enter your yard and even your home. On the contrary, if you leave food out in an area located far away from your house and garden, it might be possible that the squirrels will never feel the need to move and explore what lies beyond it.

Preventive measures for keeping squirrels away from your property include a high level of sanitation and the removal of any potential food sources, however, for more details on how to keep squirrels at bay, you can read our article on ways in which you can ‘Prevent infestation with Squirrels’.  In case they have infested your property or pose a great risk in infesting it, the best way of eliminating squirrels is by baiting, trapping, or using fencing as an exclusion mechanism. For details on ‘How to get rid of Squirrels’, you can visit our related article, and learn more methods of control.

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