Tupaia minorpygmy tree shrew

Geographic Range

Pygmy tree shrews (Tupaia minor) are distributed on the Malay Peninsula and the islands of Borneo, Sumatra, Banggi, Balambangan, and the Lingga Island group. (Nowak, 1999)

Habitat

Tupaia minor is found in tropical forests below elevations of 1,000 m. Although it is primarily an arboreal species¸ it has been observed and trapped in both canopy and terrestrial habitats. (Holst, 1990; Nowak, 1999; Wells, et al., 2004)

  • Range elevation
    1,000 (high) m
    ft

Physical Description

Pygmy tree shrews are superficially squirrel-like in appearance, but they can be distinguished from squirrels by their long, pointed snouts and lack of long, black vibrissae. The genus Tupaia can be distinguished from other genera of tree shrews by several external characters. The tail is evenly covered by long hair, the upper section of the ear is larger than the lower lobe, and the hairless section on top of the nose is cut squarely across.

Tupaia minor is characterized by golden brown pelage on the back and limbs, and the underparts vary in color from white to a light cream color. Claws on hands and feet are sharp and moderately curved, allowing for climbing. Pygmy tree shrews move in a semiplantigrade posture. This posture allows a tree shrew to keep its center of gravity close to the tree upon which it is climbing. While grasping on to branches, the pollex and hallux of T. minor become divergent from the other digits. This is an adaptation to arboreal life.

Tupaia minor has an average mass of 60 g and an average head and body length of 124 mm. (Emmons, 1991; Holst, 1990; Nowak, 1999; Sargis, 2001)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    50 to 70 g
    1.76 to 2.47 oz
  • Average length
    124 mm
    4.88 in

Reproduction

Information on the mating system of this species is not available. However, other species in the genus show either polygyny or polygynandry. In Tupaia glis, a single male rules over a group containing both males and females, although only the dominant male mates with females. Tupaia montana is reported to be slightly more social, with two mutually tolerant males in a group mating with the females. It is not known where in the spectrum of variation T. minor falls, but males of most species in the genus Tupaia form linear dominance heirarchies, which suggests that polygyny of some form may be the rule. (Nowak, 1999)

Tupaia minor has a litter size that ranges from 1 to 3 young. Females reach sexual maturity at approximately 46 g, and males reach sexual maturity at approximately 16.3 g. Very little else is known about the reproductive behavior of T. minor. Tupaiids, in general, have a gestation period of 45 to 55 days, and give birth to young weighing from 6 to 10 g. Weaning occurs at approximately 30 days, and sexual maturity is reached at approximately 2 months. After reaching sexual maturity young are forced out of the parental territory.

After giving birth, females become receptive to copulation at once. Breeding in captivity and in the wild can occur year round. (Hayssen, et al., 1993; Holst, 1990; Nowak, 1999)

  • Breeding interval
    Breeding can occur every 45 to 55 days.
  • Breeding season
    Breeding may occur year around.
  • Range number of offspring
    1 to 3
  • Average number of offspring
    2
    AnAge
  • Range gestation period
    45 to 55 days
  • Average weaning age
    30 days
  • Average age at sexual or reproductive maturity (female)
    2 months
  • Average age at sexual or reproductive maturity (male)
    2 months

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)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

To date, all life span knowledge for T. minor is limited to data from captive subjects. In captivity they tend to live a maximum of 9 to 10 years. (Holst, 1990)

  • Typical lifespan
    Status: captivity
    9 to 10 years

Behavior

Like most tupaiids, T. minor is diurnal, but it is one of the only predominantly arboreal species. It spends the majority of its time within the canopy, but it is known to forage in all forest strata, from the understory to the canopy. Tupaia minor is highly active, and alternates its time between feeding, running, playing, and resting.

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)

  • Range territory size
    500 to 8000 m^2

Home Range

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)

Communication and Perception

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)

Food Habits

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 microorganisms 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)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • Plant Foods
  • fruit

Predation

Predation on members of the genus Tupaia undoubtedly occurs, although details on predatory interactions are lacking in the literature. These smallish mammals are likely prey for snakes, larger mammals, and raptors.

Ecosystem Roles

It has been suggested that T. minor may play a role as a seed disperser for several Ficus fig species. (Shanahan and Compton, 2000)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

These forest animals are not known to have any positive economic importance on humans.

Economic Importance for Humans: Negative

These tree shrews are not known to have a negative effect on human economies.

Conservation Status

All species of Tupaiidae, including T. minor, are listed on Appendix II of CITES. It is thought that this designation was a result of the entire order Primates being added to the appendix in 1975. At that time the order still included Tupaiidae.

The largest problem facing these animals is human encroachment into tropical forests. This encroachment may take many forms, including logging, cultivation, and human habitation. In each case, the result is ultimately the same: habitat destruction and fragmentation.

In 1995, the IUCN published the Eurasian Insectivores and Tree Shrews: Status Survey and Conservation Action Plan. This plan outlines the status and conservation needs of tree shrews in Southeast Asia. A digital version of this plan can be obtained at: http://members.vienna.at/shrew/itsesAP95-cover.html. (Nowak, 1999; Stone, 1995)

Contributors

Michael Lelevier (author), University of Alaska Fairbanks, Link Olson (editor, instructor), University of Alaska Fairbanks.

Nancy Shefferly (editor), Animal Diversity Web.

Glossary

acoustic

uses sound to communicate

altricial

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.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

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.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

endothermic

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.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

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).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

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

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Emmons, L. 1991. Frugivory in Treeshrews (Tupaia). The American Naturalist, 138/3: 642-649.

Han, K., F. Sheldon, R. Stuebing. 2000. Interspecific relationships and biogeography of some Bornean tree shrews (Tupaiidae: Tupaia), based on DNA hybridization and morphometric comparisons. Biological Journal of the Linnean Society, 70/1: 1-14.

Hayssen, V., A. Tienhoven, A. TienHoven. 1993. Asdell's Patterns of Mammalian Reproduction. Ithaca and London: Comstock Publishing Associates.

Holst, D. 1990. Grzimek's Encyclopedia Of Mammals Volume 2. New York: McGraw-Hill Publishing Company.

Nowak, R. 1999. Walker's Mammals of the World, Vol 1, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Sargis, E. 2001. The grasping behaviour, locomotion and substrate use of the tree shrews Tupaia minor and T. tana (Mammalia, Scandentia). Journal of Zoology, 253: 485-490.

Shanahan, M., S. Compton. 2000. Fig-Eating by Bornean Tree Shrews (Tupaia spp.): Evidence for a Role as Seed Dispersers. Biotropica, 32/4a: 759-764.

Stone, D. 1995. "Eurasian Insectivores and Tree Shrews: Status Survey and Conservation Action Plan" (On-line). Accessed November 15, 2004 at http://members.vienna.at/shrew/itsesAP95-cover.html.

Wells, K., M. Pfeiffer, M. Lakim, K. Linsenmair. 2004. Use of arboreal and terrestrial space by a small mammal community in a tropical rain forest in Borneo, Malaysia. Journal of Biogeography, 31/4: 641-652.