Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels, 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.
Flying squirrels are a tribe of 50 species of squirrels in the family Sciuridae. Despite their name, they are not in fact capable of full flight in the same way as birds or bats, but they are able to glide from one tree to another with the aid of a patagium, a furred skin membrane that stretches from wrist to ankle. Their long tails also provide stability as they glide. Anatomically they are very similar to other squirrels with a number of adaptations to suit their lifestyle; their limb bones are longer and their hand bones, foot bones, and distal vertebrae are shorter. Flying squirrels are able to steer and exert control over their glide path with their limbs and tail.
Sciurinae is a subfamily of squirrels, uniting the flying squirrels with certain related tree squirrels. Older sources place the flying squirrels in a separate subfamily (Pteromyinae) and unite all remaining sciurids into the subfamily Sciurinae, but this has been strongly refuted by genetic studies.
The grizzled giant squirrel is a large tree squirrel in the genus Ratufa found in the highlands of the Central and Uva provinces of Sri Lanka, and in patches of riparian forest along the Kaveri River and in the hill forests of Karnataka, Tamil Nadu and Kerala states of southern India. The International Union for Conservation of Nature (IUCN) lists the species as near threatened due to habitat loss and hunting.
The Himalayan marmot is a marmot species that inhabits alpine grasslands throughout the Himalayas and on the Tibetan Plateau. It is IUCN Red Listed as Least Concern because of its wide range and possibly large population.
The Indian giant squirrel or Malabar giant squirrel is a large multi-coloured tree squirrel species endemic to forests and woodlands in India. It is a diurnal, arboreal, and mainly herbivorous squirrel.
Biswamoyopterus is a genus of rodent in the family Sciuridae. It contains three known species of very large flying squirrels, with B. laoensis being among the longest of all squirrels. They are distributed in forests in northeast India, southwest China and Laos. Despite their size, species in this genus tend to be very elusive; due to this, all of them have been described relatively recently. Additionally, they are easily confused with certain Petaurista giant flying squirrels that are more common and overlap in range with the rare Biswamoyopterus.
The Namdapha flying squirrel is a flying squirrel endemic to Arunachal Pradesh in northeast India, where it is known from a single zoological specimen collected in Namdapha National Park in 1981.
The Bolivian squirrel is a tree squirrel that is endemic to South America. Little is known of the species, which may represent a species complex.
The red giant flying squirrel or common giant flying squirrel is a species of rodent in the family Sciuridae (squirrels). It is found in a wide variety of forest–types, plantations and more open habitats with scattered trees in Southeast Asia, ranging north to the Himalayas and southern and central China. One of the largest arboreal squirrels, all populations have at least some reddish-brown above and pale underparts, but otherwise there are significant geographic variations in the colours. The taxonomic position of those in the Sundaic region is generally agreed upon, but there is considerable uncertainty about the others, which variously have been included in this or other species, or recognized as their own species.
Prevost's squirrel or Asian tri-coloured squirrel is a colourful species of rodent in the family Sciuridae. It is found in forests in the Thai-Malay Peninsula, Sumatra, Borneo and nearby smaller islands, with an introduced population in northern Sulawesi. Although the Prevost's squirrel is declining in some regions because of habitat loss and hunting, the species is not considered threatened since it generally remains common and widespread. It can live in somewhat disturbed habitats and often visits plantations or gardens. It mostly feeds on plant material, especially fruits, but also takes insects.
The Santander dwarf squirrel is a small tree squirrel endemic to Colombia.
The red and white giant flying squirrel is a species of rodent in the family Sciuridae. It is a very large, dark rufous-red, buff and white flying squirrel found in forests at altitudes of 800–3,500 m (2,600–11,500 ft) in mainland China and 1,200–3,750 m (3,940–12,300 ft) in Taiwan, although the population of the latter island is distinctive and likely better regarded as a separate species, the Taiwan giant flying squirrel. Additionally, the red and white giant flying squirrel possibly ranges into northeastern South Asia and far northern Mainland Southeast Asia. This squirrel has a wide range and is relatively common, and the International Union for Conservation of Nature lists it as being of "least concern".
Petaurista is a genus of rodent in the family Sciuridae. They are large to very large flying squirrels found in forests and other wooded habitats in southern and eastern Asia.
The spotted giant flying squirrel, also known as the lesser giant flying squirrel, is a species of rodent in the family Sciuridae. It is found in hill and mountain forests at altitudes of 200–4,000 m (660–13,120 ft) in Southeast Asia north to central China and the east Himalayan region, although the northern populations sometimes are regarded as separate species as the grey-headed giant flying squirrel, Chindwin giant flying squirrel and P. marica. Two of these, as well as a few other populations, lack the white spots on the upperparts for which it is named. Although a large flying squirrel, it is a relatively small giant flying squirrel.
Hodgson's giant flying squirrel is a species of rodent in the family Sciuridae. This large flying squirrel lives in Himalayan forests in Asia. Like other flying squirrels, it is nocturnal and able to glide long distances between trees by spreading out its patagium, skin between its limbs.
The Indian giant flying squirrel, also called the large brown flying squirrel or the common giant flying squirrel, is a species of rodent in the family Sciuridae. It is capable of gliding flight using a skin membrane, the patagium, stretched between front and hind legs. It is found in mainland Southeast and South Asia, and southern and central China.
The black giant squirrel or Malayan giant squirrel is a large tree squirrel in the genus Ratufa native to the Indomalayan zootope. It is found in forests from northern Bangladesh, northeast India, eastern Nepal, Bhutan, southern China, Myanmar, Laos, Thailand, West Malaysia, Cambodia, Vietnam, and western Indonesia.
The Japanese dwarf flying squirrel is one of two species of Old World flying squirrels in the genus Pteromys. During the day this squirrel hides in a hole, usually in a coniferous tree, emerging at night to feed.
The Mechuka giant flying squirrel is a species of rodent in the family Sciuridae. First described in 2007 from East Himalayan forests at altitudes of 1,500–2,500 m (4,900–8,200 ft) in the region of Mechuka of north-central Arunachal Pradesh in India, its taxonomic status and position is not fully resolved. it was originally described as P. nigra but has been replaced by mechukaensis because it was a primary homonym of P. nigra Wang 1981.
