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. ("Common tree shrew (Tupaia glis)", 1995; "Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 2001)
The primary habitat of T. glis is deciduous tropical forests. Common tree shrews have also been reportedly seen in fruit plantations and local gardens. ("Common tree shrew (Tupaia glis)", 1995; "Scandentia, Tree shrews (Tupaiidae)", 2004)
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. ("Common tree shrew (Tupaia glis)", 1995; "Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 1985; "Tree Shrews", 2001)
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. ("Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 2001; Kawamichi and Kawamichi, 1982; Martin, 1968)
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. ("Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 1985; Binz and Zimmermann, 1989; Hayssen, et al., 1993; Kawamichi and Kawamichi, 1982; Langham, 1982; Martin, 1968)
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. ("Order Scandentia", 1999; "Tree Shrews", 1985; "Tree Shrews", 2001; Martin, 1968)
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. ("Common tree shrew – Tupaia glis", 2005; Jones, 1982)
Tupaia glis resembles European squirrels not only in appearance but also in behavior. Both T. glis and squirrels are unusual for small mammals in that they are diurnal. Tupaia glis is semi-terrestrial, meaning that it spends time in both trees and on the ground. However, most of the time it is found in the understory rustling through leaves, frequently foraging. Tupaia glis is often described as continuously scurrying around with “jerky” movements. ("Common tree shrew (Tupaia glis)", 1995; "Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 1985; Langham, 1982)
This species exhibits sexual dimorphism in home range size. The average home range of a male T. glis is reported to be 10,174 sq m, whereas for females it is 8,809 sq m. When a social unit is formed, it consists of parents and their offspring. The home range is shared and protected by all individuals of this social unit. Individuals forage independently during the day throughout the entire home range. Territories are thought to have the same boarders as the home ranges, since there is little overlap in home ranges for animals of the same sex, and fighting occurs at boarders. The social unit on each home range is modified every generation when the male offspring disperse to find their own home ranges. The females leave after the males have dispersed. The population density per hectare in common tree shrews was found to be 6 to 12 in Thailand and 2 to 5 in the Malaysia Peninsula. ("Common tree shrew (Tupaia glis)", 1995; "Order Scandentia", 1999; "Tree Shrews", 1985; Langham, 1982)
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. ("Tree Shrews", 1985; "Tree Shrews", 2001; Binz and Zimmermann, 1989)
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. ("Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 1985)
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 wagleri), 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. ("Common tree shrew – Tupaia glis", 2005; John Ramsay and Kathy, 1974)
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.
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. (Sherwood, et al., 2003; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 1985; Sherwood, et al., 2003)
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. ("Tree Shrews", 1985)
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. ("Common tree shrew (Tupaia glis)", 1995)
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. ("Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004)
Barbara Lundrigan (editor, instructor), Michigan State University, Laura Cisneros (author), Michigan State University.
Nancy Shefferly (editor), Animal Diversity Web.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
found in the oriental region of the world. In other words, India and southeast Asia.
chemicals released into air or water that are detected by and responded to by other animals of the same species
having more than one female as a mate at one time
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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