A very interesting and controversial subject involving tree shrews, family Tupaiidae, is their placement on the phylogenic tree. Since their discovery, tree shrews have been placed into various different orders including Afrosoricida and Macroscelididae. In the 1920s, Le Gros Clark reported similarities in musculature, brain, skull, eye development and reproductive characteristics between tree shrews and primates. Tree shrews were officially moved into the Order Primates in 1945 by Simpson’s seminal classification. In 1965, this classification was again questioned when the similarities between tree shrews and primates were determined to be either convergent because of a shared lifestyle or retained from a very early ancestor. Although some continue to classify the family Tupaiidae in the Order Primates, more commonly the family Tupaiidae resides in a separate order, Scandentia, which is thought to have characteristics of a highly developed Insectivore and a very primitive Primate.
Common tree shrews have been known to use sent marking as a form of communication. They have two scent glands: one located in the sternum and the other in the abdomen. Tupaia glis rubs these glands on objects or other tree shrews. In addition to scent glands, T. glis also uses urine and feces for scent marking territories. Not only does T. glis use olfactory communication but it also uses many vocalizations in communication. Binz and Zimmermann (1989) discovered eight distinct sounds made by the genus Tupaia. When species in the genus Tupaia are even slightly disturbed a “chattering” noise is produced. It is thought that this noise might be a mob call. Varying pitches of “screams” have also been identified when the tree shrew is immediately threatened such as a deafening "squeal" which expresses aggression. Binz and Zimmerman (1989) also discovered that mating and courtship activities involve both “clucking” and “whistling” sounds.
Communication Channels: acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
The IUCN lists T. glis as Low Risk and of the least concern at this point in time. This may be due to its rapid breeding and fast colonization.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
A possible negative impact T. glis may have on humans is its role as a pest in fruit plantations. However, evidence is still lacking to support the contention of common tree shrews as pests.
Negative Impacts: crop pest
Tupaia glis does not seem to have affected human economies beneficially. Tupaia glis is not even hunted by the local people as it is considered unpleasant to eat. However, T. glis has shown to be very important in research on evolution of primates. Most of the research conducted on common tree shrews has been optical research.
Positive Impacts: research and education
There is little reported in the literature on the impact that T. glis has on its environment. Some possible roles that T. glis may play in its ecosystem are as a seed disperser or population control of certain insect species.
Ecosystem Impact: disperses seeds
Tupaia glis spends a majority of its time foraging for food. Its diet includes an assortment of arthropods, fruit, and leaves. Common tree shrews have even been seen eating small vertebrates! Even though T. glis is to some extent arboreal, most of the foraging occurs on the forest floor. It is often seen moving quickly in search for food in every nook and cranny of the forest understory. While in search of food, T. glis tends to use its snout for capturing its prey. The forepaws are used only for grabbing flying insects or objects just out of reach. T. glis eats very much in the same manner as a squirrel; it holds its food in its forepaws while sitting in a slouching position on its hind feet and rear. Although the foraging of T. glis is fairly general and unspecialized, tree shrews have a unique way of digesting fruit. During consumption they discard as much fiber as possible, decreasing the time of digestion. This digestive strategy is very similar to the one seen in fruit eating bats.
Animal Foods: amphibians; reptiles; eggs; insects; terrestrial worms
Plant Foods: leaves; seeds, grains, and nuts; fruit
Primary Diet: omnivore
Comon tree shrews, Tupaia glis, are limited to Southeast Asia. More specifically, the range of common tree shrews begins just below the Isthmus of Kra in Thailand and continues through the Malayan Peninsula into Indonesia, which includes Sumatra, Java, and surrounding islands.
Biogeographic Regions: oriental (Native )
The primary habitat of T. glis is deciduous tropical forests. Common tree shrews have also been reportedly seen in fruit plantations and local gardens.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest
Other Habitat Features: agricultural
Common tree shrews are known to live about 2 to 3 years in the wild. However, the longest-lived common tree shrew and tree shrew in general was in captivity for 12 years and 5 months.
Range lifespan
Status: captivity: 12.5 (high) years.
Typical lifespan
Status: wild: 2 to 3 years.
Average lifespan
Status: captivity: 12.4 years.
Tupaia came from the Malay word “tupai,” meaning squirrel. This is fitting since common tree shrews, with their pointy snouts and bushy tails, bear a resemblance to squirrels. However, T. glis can be distinguished from squirrels by the absence of long whiskers. The genus Tupaia is known to encompass species with the least specialized characteristics of all tree shrews. This is in part due to the semi-terrestrial lifestyles of species in this genus. Although arboreal tree shrews tend to have a relatively small body size with a short snout, a long tail, eyes facing forward, and poorly developed claws, terrestrial tree shrews have a larger body size with a long snout, short tail, eyes oriented laterally and well-developed claws. Tupaia glis has characteristics that are intermediate to these extremes.
Tupaia glis has an average body weight of 142 grams, a head and body length of 19.5 cm and tail length of 16.5 cm. Its pelage is dense and dark brown on the dorsal region of the body and orange-rufous ventrally. A pale shoulder stripe is present. Multiple subspecies and races are designated at decreasing latitude in the Malaysia Peninsula; these are based on progressive lightening of the dorsal color. There is no sexual dimorphism present in common tree shrews.
All digits have long, sharp claws, which are used for climbing. Tupaia glis has small ears and moderately sized eyes compared to most small mammals such as rodents and shrews; the eyes are positioned laterally.
Average mass: 142 g.
Average length: 19.5 cm.
Sexual Dimorphism: sexes alike
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 200 g.
Average basal metabolic rate: 0.522 W.
Natural predators of Tupaia glis include snakes, birds of prey, and small carnivores. In the literature there is no reference to any particular predators, however a few possible canidates are yellow throated martens (Martes flavigula), Wagler's pitviper (Tropidolaemus laticinctus), red tail racers and hawks. These species could be possible predators since they all are diurnal, hunt at the same forest level that common tree shrews are found, and have been reported to prey on other arboreal, small mammals.
Anti-predator Adaptations: cryptic
For the most part, common tree shrews are monogamous. The union between females and males seems to be prominent and permanent as revealed by scent marking between the pair and sharing of the same territory. However, monogamy in this species may be the result of some unexplained ecological constraints.
An exception to strict monogmamy has been noted in Singapore, where a polygynous mating system occurs. In this case, a male's home range may encompass the home ranges of several females, leading him to a polygynous mating system. Home ranges of like-sexxed individuals do not overlap.
Another deviation from a monogamous system is seen in captivity, where one male dominates completely all other males, and only the dominant male mates with the females.
Mating System: monogamous ; polygynous
Although T. glis has a year round breeding season in the wild, breeding has been shown to peak between February and June on the Malaysian Peninsula. The finding that T. glis females experience estrus during December followed by another estrus, with births occurring in February and April, further suggests a February to June breeding peak. Kawamichi and Kawamichi (1982) reported that T. glis is reproductively inactive from August to November.
The estrous cycles last anywhere from 8 to 39 days and gestation has been reported to extended from 40 to 52 days. Reproduction in T. glis is characterized by delayed implantation of the blastocyst despite the female being in estrus during the interbirth phase. This maximizes the number of offspring that a female can produce in a lifetime.
Common tree shrews have two pairs of teats and can produce up to 3 offspring per pregnancy. The young are altricial and have a birth weight around 10 to 12 grams. Ears and eyes do not begin to open until 10 and 20 days after birth, respectively. Young develop slowly while still in the nest and feeding off their mother’s milk. After 36 days, they are able to leave the nest and are then weaned. Their development after leaving the nest is much more rapid. Both male and female offspring become sexual mature within 3 months. Females can start producing young as early as 4.5 months of age. Since gestation is relatively short, and maturation is quick, common tree shrews are very good colonizers.
Breeding interval: The time elapsing between subsequent litters in this species is not known.
Breeding season: The breeding season peaks during February to June.
Range number of offspring: 1 to 3.
Range gestation period: 40 to 52 days.
Average weaning age: 36 days.
Average age at sexual or reproductive maturity (female): 3 months.
Average age at sexual or reproductive maturity (male): 3 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; delayed implantation
Average birth mass: 12.94 g.
Average number of offspring: 2.
Average age at sexual or reproductive maturity (male)
Sex: male: 90 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 90 days.
Common tree shrews are unique in their basic parental care. An unusual component is the construction of two separate nests, one for the parents to sleep in and another where the offspring are kept. Nests are often made by the male in holes, trees, under roots, or in hollow bamboo, and are filled with dry leaves.
Although it is unusual among mammals for a male to build the nest for the young, even more extraordinary is the small amount of time the mother spends with her offspring! Female common tree shrews visit their young every 48 hours to nurse them for 10 to 15 minutes. In that time, an offspring will receive 5 to 15 grams of milk that is high in protein and low in carbohydrates. The maternal care does not include any toilet care. The total average amount of time that a female spends with her offspring while in nestling phase is only about an hour and a half.
Since parental care is very restricted, the parents would not be able to identify their offspring without scent marking the young or the nest. If this is not done, the female may dispose of her young.
After 36 days, juveniles depart from their nest and join their parents in the other nest. Once the offspring have joined their parents in one nest they are completely weaned of their mother's milk and resemble miniature models of their parents. Parental care is still limited when the offspring have joined their parents in one nest.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female); pre-independence (Protecting: Male, Female); post-independence association with parents
The common treeshrew (Tupaia glis) is a small mammal in the treeshrew family Tupaiidae, and is native to Thailand, Malaysia, and Indonesia. It has been listed as Least Concern by IUCN as it remains common and displays some adaptability to ongoing habitat loss.[1]
The common treeshrew is one of the largest among treeshrews. Average body length is between 16 and 21 cm (6.3 and 8.3 in), and average weight is around 190 g, with varying colours of reddish-brown, greyish or black upper parts and whitish belly. Its long, bushy tail is dark greyish-brown and almost reaches the length of the body. The paws are bare with sharp nails, and with a naked patch of skin above its long nose. Both sexes are similar. The animal has a head and body length of 13–21 cm and a tail length of 12–20 cm.[3] The common treeshrew usually has a white, pale stripe on each shoulder.
The two subspecies are T. g. longipes and T. g. salatana, with T. g. longipes being duller in color than T. g. salatana. The underparts of T. g. longipes are dull buff to reddish-buff, and the underside of the tail is greyish. The underparts and underside of the tail are dark reddish in T. g. salatana. Similar species are Tupaia splendidula and Tupaia montana.
Common treeshrews occur south of about 10°N latitude in southern Thailand through mainland Malaysia and adjacent coastal islands to Singapore. They inhabit protected areas, including the Pasoh Forest Reserve on the Malay Peninsula and Krau Wildlife Reserve.[1] In Indonesia, they are found on the islands of Siberut, Batu, Sumatra, Java, Bangka, Riau, Lingga and Anambas.[4] Usually they are found in primary dipterocarp forest, but are tolerant to some degree of habitat modification. They have also been recorded from secondary forest, plantations, fruit orchards, and trees near housing areas.[5]
Common treeshrews are probably present throughout the lowlands and hills up to 1,100 m (3,600 ft) in the Kelabit Highlands of Borneo. The subspecies T. g. longipes occurs in the north of Borneo, in Sarawak, and in East Kalimantan, including Sabah. The subspecies T. g. salatana occurs in the south of Rajang River and Kayan River in Borneo.[6]
Common treeshrews are active during the day, and forage for food alone or in pairs, mainly on the ground, among shrubs and tree holes. They feed on fruits, seeds, leaves, and insects, especially ants and spiders.[7] They are also reported to catch lizards.
They are very agile in climbing both large vertical tree trunks and bushes, and occasionally jump from stems of a young tree to that of another as much as 60 cm (24 in) away. Their climbing is concentrated in lower heights. They frequently scent-mark their territories by chest and anogenital rubbing with a secretion from glands on chest and scrotum. Adult males are more secretory than females and juveniles. In the Bukit Timah Nature Reserve, mean home ranges of adult males were estimated at 10,174 m2 (109,510 sq ft), of adult females at 8,809 m2 (94,820 sq ft), of juvenile males at 7,527 m2 (81,020 sq ft), and of juvenile females at 7,255 m2 (78,090 sq ft), with partial overlaps between male and female ranges varying from 0.4% to 56.8%. Home ranges of adult residents of the same sex overlap to a lesser degree than those of opposite sexes. A male's range may include the ranges of two or three females. A high overlap between ranges of one adult male and one adult female indicates they form a stable pair. Juvenile ranges of either sex adjoin or overlap with ranges of adults, suggesting the juveniles are family members. Individuals of the same sex are involved in aggressive territorial chases.[8]
Juvenile males depart from their family's territory sooner than juvenile females.[7]
Both sexes of common treeshrews are sexually mature at the age of about three months. In captivity, females give birth for the first time at the age of about 4.5 mo, usually in February. A postpartum oestrus results in more births in April. Their oestrus cycle is eight to 39 days, and the gestation period lasts 40 to 52 days, after which a litter of one to three individuals is born. The newborn offspring weigh about 10 to 12 grams. Females suckle their young every other day, and neglect their young as long as possible. They would not even be able to identify their own young if they did not mark them with the scent produced from glands in their sternum and abdomen. Juveniles leave the nest between 25 and 35 days of age. Longevity of a captive common treeshrew has been recorded as 12 yr and 5 mo.[7]
From October to December, common treeshrews are reproductively inactive.[8] The mating season starts at the onset of the monsoon season in December and lasts until February. Oestrus and proestrus behavior is characterized by adult males pursuing adult females. Males emit chattering, and appear to be extremely excited. They also chase each other and fight. Females do not actively choose a partner among the male participants of chases. The dominant male gains access to females.[9]
In tropical rainforest habitats in West Malaysia, population density varies from two to five animals per hectare. Their annual breeding coincides with the abundance of invertebrates after the dry season. Their main reproductive period is between February and June, and their litter size is invariably two. Some females breed more than once a season, and the age at first pregnancy is seven months. The main period of emigration or mortality of young is during the breeding period or monsoon.[10]
The species was first described in February 1820 by the French explorers Pierre-Médard Diard and Alfred Duvaucel in their jointly written article "Sur une nouvelle espèce de Sorex — Sorex Glis", which is preceded by an illustration. They observed specimens in Penang and Singapore, and considered them a species of Sorex, and not as a new genus.[2] Between 1821 and 1940, several zoologists described the species from other areas. The species still retains many forms of uncertain rank and validity, and is pending a detailed study. Some forms were formerly considered synonyms of Tupaia glis; some were elevated to species level. Synonyms include:[4]
Common treeshrews are threatened due to deforestation and ensuing human activities in agriculture (for example, using trenchers to dig ditches), plantations, and commercial logging. Moreover, other pressures, such as hunting for food and sport, can create pressure to the species.[4]
Tupaia glis is used by researchers as animal models for human diseases because of their close relationship to primates, and their well-developed senses of vision and hearing. Research studies have included hepatitis.[12] Another instance has been documented where an individual of Tupaia glis developed breast cancer.[13]
The common treeshrew (Tupaia glis) is a small mammal in the treeshrew family Tupaiidae, and is native to Thailand, Malaysia, and Indonesia. It has been listed as Least Concern by IUCN as it remains common and displays some adaptability to ongoing habitat loss.
