Tupaia belangeri

Geographic Range

Northern tree shrews are found in South East Asia (IUCN Red List, 2012). The IUCN (2012) specifies that they are native to Bangladesh, Bhutan, Cambodia, China, Lao People's Democratic Republic, Malaysia, Myanmar, Thailand and Vietnam.

• Biogeographic Regions
• oriental oriental
  • native native

Habitat

Northern tree shrews inhabit a variety of forest habitats. They live in tropical and subtropical areas, which are usually moist environments (IUCN, 2012). They have also been recorded in shrub lands and artificial plantations and rural gardens. IUCN (2012) reports 3000 meters as the highest known elevation for tree shrew, recorded in China. Tree shrews inhabit areas about 25 degrees Celsius, with at least 45 to 50% humidity (Fuchs and Corbach-Sohle, 2009).

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

Physical Description

Northern tree shrews have greyish, olive fur with an elongated snout (Smithsonian National Zoological Park, 2012). The dental formula of the Tupaiidae is incisors 2/3, canines 1/1, pre-molars 3/3, and molars 3/3 (Fuchs and Corbach-Sohle, 2009). Northern tree shrews are moderately sexually dimorphic (Collins and Tsang, 1987; Schehka et al., 2007). Male tree shrews have a larger body size and ring of white hair around the eye compared to females. Males also have a broader skull than the females (Collins and Tsang, 1987).

Fuchs and Corbach-Sohle (2009) describe the difficulty in determining the sex of young tree shrews. As pups the external genitalia of both males and females look alike. Males have a slender and elongate penis, which is posterior to scrotal testes, which can be retracted into the abdominal cavity if the individual is stressed. In females the clitoris is greatly elongated and grooved on its ventral surface. In neonatal shrews the urethra opens together with the vagina as a single opening at the base of the clitoris; this is what looks like the males penis in young female tree shrews. However the clitoris does not have a tubular sheath like the penis.

Northern tree shrews have a mass of approximately 50 to 270 grams, Head to Body Length of 12 to 21 cm and a tail length ranging from 14 to 20 cm, usually close to the length of their body (Fuchs and Corbach-Sohle, 2009). Shrew body temperature has been described, ranging from about 35 degrees Celsius to 40 degrees Celsius; this 5 degree difference is much larger than most endothermic animals (Fuchs and Corbach-Sohle, 2009).

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• sexes shaped differently

Reproduction

Northern tree shrews have a monogamous mating system (Collins and Tsang, 1987). Introductions between a mating pair are possibly the hardest part of breeding for northern tree shrews. Copulation can occur within a few hours if the female accepts the male (Fuchs and Corbach-Sohle, 2009). However, they usually use more aggressive behaviors. Fuchs and Corbach-Sohle (2009) suggest two explanations: first, that the individuals merely don't like each other, and second that to mate one animal has to enter the others territory. Northern tree shrews, male or female, will defend their territory against intruders. If the couple can overcome this they will form a stable breeding pair and continue to breed together. Females have an 8 to 12 day estrous cycle. Ovulation is thought to be induced by copulation (Martin, 1990)

• Mating System
• monogamous monogamous

Under natural and artificial conditions Fuchs and Corbach-Sohle (2009) observed that breeding can occur at any time of the year; no peak periods were found. Males and females become sexually reproductive around the same time. Males will be active between four and five months and females can give birth to their first litter at approximately 4 months old. Northern tree shrews have a litter size of 1 to 5 young. The gestation period occurs for approximately 41 to 45 days and females give birth to hairless, altricial young. Pups ears open at around 10 days and their eyes open at approximately 20 days after birth. Female young tend to be heavier than males, but on average young will have a birth mass of 6 to 10 grams (Fuchs and Corbach-Sohle, 2009). Young will drink their mothers milk until they are around 35 days old when they wean off the liquid diet. Northern tree shrews reach puberty at about 2 months old and can be separated from their mother at about 50 to 60 days (Fuchs and Corbach-Sohle, 2009). Older mothers may have problems with infertility, still birth, cannibalism or abortion. These problems can also occur in females that are stressed, which is likely in tree shrews as they are highly susceptible to stressors (Fuchs and Corbach-Sohle, 2009).

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• induced ovulation induced ovulation
• viviparous viviparous

Immediately after birth the mother will nurse her pups and thereafter only return to feed her young once every 48 hours (Fuchs and Corbach-Sohle, 2009). They receive approximately 5 to 10 milliliters of milk, with a relatively high fat content of about 25%. Pups consume this amount of milk in approximately 2 to 10 minutes. As a result pups have less than 2 hours contact with their mother during the 30 to 35 day period. Martin (1990) described that as the lowest mother to infant contact and smallest parental investment for viviparous mammals described thus far. Males are not involved in parental care after copulation (Fuchs and Corbach-Sohle (2009).

• Parental Investment
• altricial altricial
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
• pre-independence
  • provisioning
    • female
• post-independence association with parents

Lifespan/Longevity

Captive northern tree shrews live 9 to 12 years (Fuchs and Corbach-Sohle, 2009). The lifespan of northern tree shrews in the wild is currently unknown.

Behavior

Typically northern tree shrews live in monogamous pairs (Smithsonian National Zoological Park, 2012). One adult male and female share overlapping territories. Males and females will both defend their territories against conspecifics year round. Territorial fights are documented between adults of the same sex (Fuchs and Corbach-Sohle, 2009). Tree shrews use scent marking, excreted from a gland on their chest, to mark their territories (Fuchs and Corbach-Sohle, 2009). The young tree shrews leave the nest around the onset of puberty and they become completely self sufficient (Collins and Tsang, 1987).

• Key Behaviors
• arboreal arboreal
• terricolous
• motile motile
• territorial territorial

Home Range

Northern tree shrews have relatively stable home ranges of about 2 acres or 0.81 hectares (Smithsonian National Zoological Park, 2012).

Communication and Perception

Northern tree shrews make 8 distinct sounds (Fuchs and Corbach-Sohle, 2009). Of these 4 can be associated with functional categories that are described by Binz and Zimmermann (1989): alarm, attention, contact, and defense. Tree shrew noises can range from 0.4 to 20 kHz. The structure of the sounds depend on the status and motivation of the individuals; their pitch increases with fear and decreases in pitch (or increases in frequency) with increased aggression (Kirchhof et al., 2001). Kirchhof et al. (2001) also note that tree shrews do not use ultrasonic localisations. Tree shrews use scent marking to indicate boundaries of their territories (Fuchs and Corbach-Sohle, 2009).

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Northern tree shrews are predominantly insectivorous, but eat fruits to obtain extra nutrients and calories to their high protein diet (Fuchs and Corbach-Sohle, 2009).

Tree shrews do not absorb much water from their food and they are unable to go more than 1 day without free water (Fuchs and Corbach-Sohle, 2009)

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
• herbivore herbivore
  • frugivore frugivore
• omnivore omnivore

• Animal Foods
• eggs
• insects

• Plant Foods
• fruit

Predation

It has been noted that tree shrews will react to predation risk (Schehka et al., 2007; Fuchs and Corbach-Sohle, 2009). They will display defensively to a threat, specifically baring teeth and making high pitched, loud vocalizations (Schehka, 2007). Specific predators of northern tree shrews are not specificed. However, due to their size and behavior possible predators could include, large birds of prey, snakes, and potentially some carnivorous mammals.

• Anti-predator Adaptations
• aposematic aposematic
• cryptic cryptic

Ecosystem Roles

While the main food source of northern tree shrews is insects, they also eat fruit to supplement their diet. It could be inferred that they play a role in the seed dispersal of fruit bearing trees.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

There are no known positive economic effects of northern tree shrews.

Economic Importance for Humans: Negative

Northern tree shrews have well defined, sharp teeth. Should they feel threatened these could be used as a defense mechanism. It is highly unlikely that these animals would attack a human but a small possibility. Otherwise there are no known negative economic effects of northern tree shrews.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

IUCN (2012) describe northern tree shrews as the Least Concern status. They have a population that is stable, and they are common throughout their range. IUCN (2012) lists them as least concern because of their wide range, abundance, ability to tolerate disturbance, and they are present in many protected areas.

Additional Links

Encyclopedia of Life

Contributors

Teagan Lowther (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Washington, Laura Podzikowski (editor), Special Projects.

References

Binz, H., E. Zimmermann. 1989. The vocal repertoire of adult tree shrews (Tupaia belangeri). Behavior , 109: 142-162.

Collins, P., W. Tsang. 1987. Growth and Reproductive Development in the Male Tree Shrew (Tupaia belangeri) from Birth to Sexual Maturity. Biology of Reproduction , 37: 261-267.

Fuchs, E., S. Corbach-Sohle. 2009. "Tree Shrews" (On-line pdf). UFAW Handbook Tree Shrews. Accessed November 18, 2012 at http://www.unifr.ch/inph/vclab/assets/files/PDFs/pdf_1/UFAW%20Handbook%20Tree%20shrews.pdf .

IUCN, 2012. "Tupaia belangeri (Northern Treeshrew, Northern Tree Shrew)" (On-line). The IUCN Red List of Threatened Species. Accessed November 18, 2012 at http://www.iucnredlist.org/details/41492/0 .

Kirchhof, J., K. Hammerschmidt, E. Fuchs. 2001. Aggression and Dominance in Tree Shrews (Tupaia belangeri). Agonistic pattern is reflected in vocal patterns.. Pp. 409-414 in Prevention and Control of Aggression and the Impact on its Vicitms . New York: Kluwer Academi/Plenum Publishers.

Martin, R. 1990. Primate Origins and Evolution . London: Chapman & Hall.

Schehka, S., K. Esser, E. Zimmermann. 2007. Acoustical Expression of Arousal in Conflict Situations in Tree Shrews (Tupaia belangeri). J Comp Physiol A , 193: 845-852.

Smithsonian National Zoological Park, 2012. "Small Mammals" (On-line). Small Mammals: Northern Tree Shrew - National Zoo|FONZ. Accessed November 18, 2012 at http://nationalzoo.si.edu/Animals/SmallMammals/fact-northerntreeshrew.cfm) .

Tsang, W., P. Collins. 1985. Techniques for hand rearing tree-shrews (Tupaia belangeri) from birth. Zoo Biology , 4: 23-31.