| Amazon dwarf squirrel | |
|---|---|
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Sciuridae |
| Genus: | Microsciurus |
| Species: | M. flaviventer |
| Binomial name | |
| Microsciurus flaviventer (J. E. Gray, 1867) | |
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| Amazon dwarf squirrel range | |
The Amazon dwarf squirrel (Microsciurus flaviventer) is a chipmunk-sized tree squirrel native to South America.
As its name suggests, the Amazon dwarf squirrel is relatively small, with a head-body length of 12 to 16 cm (4.7 to 6.3 in) and a tail 8 to 16 cm (3.1 to 6.3 in) long. Adults weigh between 86 and 132 g (3.0 and 4.7 oz), with males being slightly larger than females. [2] The fur varies from reddish to dull brown, fading gradually to yellow or greyish on the underparts. There is a distinctive patch of pale yellow fur behind the ears, while the tail has faint yellowish bands and white frosting. [3]
The limbs are unusually long for tree squirrels. In the forelimbs, the humerus and radius are of equal length, an adaptation thought to increase the squirrel's ability to climb large trees, compensating for a lack of shoulder mobility. The longer hindlimbs allow for stronger muscles, so that the squirrel can leap over larger gaps, relative to its size, than more typically sized squirrels can. [3]
The squirrels are found in the upper Amazon Basin, broadly west of the Purus and Rio Negro rivers, in Brazil, Bolivia, Peru, Ecuador, and Colombia. They typically inhabit evergreen tropical rainforests at up to 2,000 m (6,600 ft) elevation, [3] although they may sometimes be found in more disturbed habitats. [4]
Eight subspecies of Amazon dwarf squirrel are generally recognised. [5] [3] Recent studies have indicated that the subspecies M. f. otinus, M. f. sabanillae, M. f. similis, and M. f. simonsi are their [6] own distinct species rather than subspecies. The same study also showed that M. f. otinus and M. f. similis are more closely related to Microsciurus mimulus and Sciurus pucheranii than they are to M. flaviventer.
| Subspecies | Authority | Synonyms | Distribution |
|---|---|---|---|
| M. f. flaviventer | Gray (1867) | manarius | Western Brazil, northeastern Peru |
| M. f. napi | Thomas (1900) | avunculus, florenciae | Northeastern Ecuador |
| M. f. otinus | Thomas (1901) | none | Western Colombia |
| M. f. peruanus | J. A. Allen (1897) | none | Northern Peru |
| M. f. rubrirostris | J. A. Allen (1914) | rubicollis | Southern Peru |
| M. f. sabanillae | Anthony (1922) | none | Southern Ecuador |
| M. f. similis | Nelson (1899) | none | Far western Colombia |
| M. f. simonsi | Thomas (1900) | none | Central eastern Ecuador |
The squirrels use all levels of the forest, from the ground to the tree canopy, but are most commonly found in the understory. They feed on arthropods, tree bark, and fungi, and have been observed to closely follow flocks of birds while foraging, although the reason for this is unclear. They are diurnal and highly arboreal, even for tree squirrels, frequently jumping from branch to branch. They spend the night in nests formed from plant fibres, and located several metres above the ground. [3]
They are mostly solitary, but may be found with others feeding on the same tree. Their calls include a bird-like "trill" and a series of soft "chucks" used as an alarm call. Very little is known of their reproduction, although litters are thought to be small. [3]
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 genus Sciurus contains most of the common, bushy-tailed squirrels in North America, Europe, temperate Asia, Central America and South America.
The southern Amazon red squirrel, is a squirrel species from South America where it inhabits forests in much of north-western South America east of the Andes. Three subspecies are currently recognised. It is a dark red colour, or a dark brown grizzled with ochre, has whitish underparts and grows to a total length of 48 to 63 cm, including a very long tail. It spends much of its time on the ground in the undergrowth and feeds largely on nuts. Little is known of its breeding habits, but it is a sociable species, several individuals often feeding together in one tree. This squirrel faces no particular threats, has a wide range and is relatively common, and the International Union for Conservation of Nature lists it as a "least-concern species".
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 Neotropical pygmy squirrel is a South American species of tree squirrel, being the only living species in the genus Sciurillus and the subfamily Sciurillinae. Genetic analysis has shown it to be the sister group to all other squirrels.
Microsciurus or dwarf squirrels is a genus of squirrels from the tropical regions of Central and South America.
Finlayson's squirrel or the variable squirrel is a species of rodent in the family Sciuridae. It is found in Cambodia, Laos, Myanmar, Thailand, and Vietnam. The species occurs in a wide range of wooded habitats, including gardens and parks in cities like Bangkok. It was named in honour of the Scottish naturalist and traveller George Finlayson.
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 red-legged sun squirrel is a species of rodent in the family Sciuridae, also commonly known as the isabelline red-legged sun squirrel. It is native to tropical western and central Africa where its range extends from Senegal in the west, through Nigeria and the Republic of Congo to Uganda and Tanzania in the east. Its natural habitats are subtropical or tropical moist lowland forests and moist savanna. This species is thought to be common and has a very wide distribution, so the International Union for Conservation of Nature has rated its conservation status as being of "least concern".
The Central American dwarf squirrel, also known as Alfaro's pygmy squirrel, is a small tree squirrel in the genus Microsciurus and tribe Sciurini found in Colombia, Costa Rica, Nicaragua, and Panama. No species of squirrel within this genus are listed as endangered, however they are rarely seen because they are extremely elusive. This suggests that their population numbers may be larger than documented.
The western dwarf squirrel is a small tree squirrel in the genus Microsciurus and tribe Sciurini found in Colombia, Ecuador, and Panama.
The Santander dwarf squirrel is a small tree squirrel endemic to Colombia.
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 Bhutan giant flying squirrel, also known as the Gray's giant flying squirrel or noble giant flying squirrel, is a species of rodent in the family Sciuridae. This species lives in Himalayan forests and it is one of the largest flying squirrels. Like other flying squirrels, it is mainly 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 Caucasian squirrel or Persian squirrel, is a tree squirrel in the genus Sciurus found in temperate broadleaf and mixed forests in south-western Asia.
The Junín red squirrel is a species of squirrel from Peru and Ecuador.
The Guayaquil squirrel is a tree squirrel endemic to Ecuador and Peru. It is a robust squirrel with a head-and-body length of 18 to 32 cm and a similar length tail. The colour is variable; in Peru, a pale morph is more common, while in Ecuador, most individuals have darker grey fur on the forequarters, dull orange hindquarters. A melanistic morph is sometimes seen. It lives largely in trees and is diurnal, feeding on seeds, flowers, and other plant material, fungi and some insects. These squirrels are also found in urban areas, living in close proximity to humans, and may be vectors for leptospirosis and Chagas disease. This squirrel faces no particular threats, has a wide range and is relatively common, and the International Union for Conservation of Nature has rated it as being of "least concern".
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 Ecuadorian squirrel monkey is a type of squirrel monkey. It had been considered a subspecies of the Guianan squirrel monkey, Saimiri sciureus, but was elevated to a full species, S. macrodon, based on a 2009 study by Carretero-Pinzón, et al. Based on subsequent genetic research by Jessica Lynch Alfaro, et al it was again reclassified as a subspecies of Humboldt's squirrel monkey.
