Pygmy Tree Shrew Tupaia minor

 

Description

The Pygmy Tree Shrew (Tupaia minor) is a species of tree shrew in the family Tupaiidae. It is found in Indonesia, Malaysia, and Thailand. and is from the order Scandentia. The generic name is derived from tupai, a Malay word for squirrels (Nowak, R., 1999). The upperparts are finely ticked with black, often with a reddish tinge, especially over the lower parts of the back. The hairs are also dark at the base. The shoulder stripe is narrow and indistinct, usually whitish or buff in colour, with the hairs the same colour throughout. The dorsal surface of the tail is also darker than the body, sometimes almost black, with the tail similar in colour, but with a longitudinal of buff or orange. It as between 4 to 6 mammae. The skull and dentition is the smallest in the genus (Lyon 1913). The rostrum is short and stubby, the braincase large and rounded. The median upper incisors are larger than T. glis but the lower third incisors are smaller; the lower  canine is better developed than in glis. . minor can be distinguished from other tree shrews by its appearance. It has upper body hair banded light and dark, giving a speckled olive-brown appearance. The upper parts are buffy and often have a reddish tinge towards the rear (Payne et al., 1985). The limbs are equal in length and have long claws. The maximum total length is about 450 mm, half of which is the tail (Feldhamer et al., 1999). The tail is long and thin, and its upper side is darker than the body (Payne et al., 1985).

Distribution

T.minor is distributed in Peninsular Thailand, peninsular Malaysia, Sumatra, the Lingga Archipelago (Indonesia), Borneo, offshore islands of Laut (Indonesia), and Banggi and Balambangan (Malaysia). From the catalogue of mammal skins in Sarawak Museum, Kuching, Sarawak, more than 30 individuals of Tupaia minor have been collected from 1891 to 1991. The specimens were mostly caught in Mt Penrisen, Mt Dulit, Mt Poi, Gunung Gading, Bau, Ulu Baram, Saribas, Kuching and Forest Research.

The species has no fossil record (Jacobs, 1980).


Behaviour, diet and reproduction

T. minor is diurnal (active in the daytime). It is often seen 3 to 8 metres above the ground, sometimes up to 20 metres, travelling along lianas or branches of small trees (Payne et al., 1985). They spend most of their time on the ground and in low bushes, nesting in tree roots and fallen timber. According to Lelevier et al., 2005, T. minor moves in a semiplantigrade posture which allows it to keep its centre of gravity close to the tree. The claws on its hands and feet are quite sharp and moderately curved, which is useful for climbing.

Captive studies show that both sexes maintain dominance hierarchies based on aggressive interactions with conspecifics. Males and females maintain pair bonds and live within the same territory together. The mechanisms behind the formation of this bond are not known. When random pairs of individuals were put together in captivity, 20% of the interactions resulted in violence. In 60% of the cases the pairing was amicable. Although the pair did not mate, they also did not fight. Mating only occurred in the remaining 20% of cases. (Emmons, 1991; Holst, 1990; Nowak, 1999; Sargis, 2001)

Home range data for T. minor is sparse within the literature, but members of the genus Tupaia hold territories that range in size from 500 to 8,000 m^2. Mated pairs and their offspring, which have not yet reached sexual maturity, hold these territories. Either urine or secretions from neck glands are used to designate territorial boundaries. tupaia minor probably is similar in these regards. (Holst, 1990)

 

The digestive tract of T. minor is comprised of a small, simplified stomach, a long, narrow small intestine, a narrow pouch-like cecum, and a smooth large intestine. The gut of T. minor lacks the plant fermentation micro-organisms needed to digest plant cell walls. The through time for digested materials ranges from 20 minutes to 45 minutes.

Tupaia minor is omnivorous. Its diet is comprised of a wide variety of invertebrates (including insects and worms) and fruit.

The method of processing fruit for ingestion is dependent on the size and rigidity of the item. Captive observations showed that small fruit is placed into the mouth and chewed. The skin and seeds are ejected from the mouth, and juice and soft pulp are ingested. Ejection of inedible items is accomplished with the help of a forepaw or the tongue. Observations of T. minor in the wild differ slightly. Wild individuals very rarely eject seeds. Fruit that is firm and larger than the gape is often problematic. The weak jaw and procumbent incisors of these animals inhibit their ability to bite off whole chunks from tough fruits. Thus, large or tough fruit is either chewed in the side of the mouth, or licked vigorously. Wild tupaiids tend to concentrate their frugivory on soft fruits that they can handle efficiently. (Emmons, 1991; Holst, 1990; Nowak, 1999; Shanahan and Compton, 2000)

Communication in these mammals has not been extensively documented. Members of the genus Tupaia are known to scent mark their territories with secretions from glands as well as with urine. Because they are diurnal, visual cues are likely to be important in communication. Most mammals also use vocal and tactile communication, especially when mating. (Holst, 1990; Nowak, 1999)



Tupaia minor is omnivorous; its diet includes insects and fruit. Scandentia has little economic significance because they do little damage to crops or plantations. However, it has been suggested that T. minor is a seed disperser for several Ficus fig species (Shanahan and Compton, 2000).

Litters of one to three young are born after a gestation period of 45 to 55 days. They breed throughout the year with a seasonal peak from May to July. According to Hose(1893) "It breeds in a nest in an old stump covered with creepers". But he was not sure if it makes the nest itself  or uses the old nest of a bird.

The rearing strategies of Tupaidea, including T. minor, are somewhat peculiar. Prior to giving birth, a female makes a large nest, consisting of leaves, wood chips, and other assorted building materials, within a fallen tree. This nest provides the young with protection from the elements and predators. The female then gives birth to her young within the nest. The young are born naked with their ears and eyes closed. Within a few minutes of birth, the young take on approximately half their initial body weight in milk. After feeding, the bellies of the young become distended from the body. The mother then leaves the nest and only returns every 48 hours to feed the young. Each visit lasts only 5 to 10 minutes. The high fat content of Tupaiid milk (~26%) enables the young to maintain a relatively high body temperature (~37 C). The high protein content of the milk (~10%) also helps the young to maintain a rapid growth rate. After approximately 4 weeks the young are able to leave the nest. This occurs with only approximately 90 minutes of parental care from the female. Males are not known to participate in care of the young. (Holst, 1990; Nowak, 1999)

Their maximum lifespan is around nine to ten years (Lelevier et al., 2005).

Threats

The Pygmy tree shrew is listed as Least Concern (LR/lc), lowest risk. Does not qualify for a more at risk category. Widespread and abundant taxa are included in this category, on the IUCN Red List of Threatened Species

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