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Dendrogale melanuraBornean smooth-tailed tree shrew

By Madeline Bernuetz

Geographic Range

Bornean smooth-tailed tree shrews are found exclusively on the island of Borneo. They are found in the mountainous northern part of the island including the mountains Kinabalu and Trus Madi in Sabah and the mountains of north-eastern Sarawak. (Thomas, 1892)

Habitat

Bornean smooth-tailed tree shrews are arboreal mammals that are endemic to the mountains of tropical northern Borneo. They are restricted to higher altitudes (above 900 m) at elevations averaging 1,524 m. At these elevations, Bornean smooth-tailed tree shrews have been observed in mossy, stunted jungles, though habitats could be more widespread, similar to the closely related northern smooth-tailed tree shrews which are found in evergreen and deciduous forests as well as bushes in rocky savannah. Northern smooth-tailed tree shrews also occasionally exploit undergrowth and understory forest tangles, which may also be true of Bornean smooth-tailed tree shrews. (Roberts, et al., 2011; Thomas, 1892; Timmins, et al., 2003; Walker, et al., 1975)

  • Range elevation
    900 (low) m
    2952.76 (low) ft
  • Average elevation
    1524 m
    5000.00 ft

Physical Description

Both members of the genus Dendrogale are distinguishable from other tree shrews due to their small body size, shortened rostrum, large ears, lack of shoulder stripes and tail covered by smooth, uniform hairs. Their morphological adaptations are suited to both an arboreal and a ground-dwelling life style. Some of their skeletal adaptations include thin ribs, an elongation of the lumbar region to allow flexion and extension of the vertebral column, a relatively short axis, and cervical vertebrae with wide inter-vertebral spaces to allow increased movement of the neck. (Endo, et al., 2003; Kolar, 1972; Sargis, 2001; Timmins, et al., 2003; Walker, et al., 1975)

Bornean smooth-tailed tree shrews have a head and body length of 110 to 150 mm with a tail length of 90 to 140 mm and a body weight of approximately 42.5 g. They are distinguishable from the closely related northern smooth-tailed tree shrews by their dark body color, long claws, and lack of prominent facial striping. Bornean smooth-tailed tree shrews have a predominantly black dorsal surface with their ventral surface and the inner surface of their legs a light brownish yellow. They have faint brownish yellow facial stripes above and below the eyes. Based on skeletal morphology, it is likely there is no sexual dimorphism in this species. The dental formula is I 3/3 C 1/1 P 3/3 M 3/3 = 38. (Endo, et al., 2003; Kolar, 1972; Sargis, 2001; Timmins, et al., 2003; Walker, et al., 1975)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    42.5 g
    1.50 oz
  • Range length
    200 to 290 mm
    7.87 to 11.42 in

Reproduction

Nothing is known about the mating system of Bornean smooth-tailed tree shrews. Generally, tree shrew species are believed to be solitary or pair living. Certain species, such as common tree shrews, have also been described living in harems with one male and multiple females. However copulation outside of these groups is believed to occur. Promiscuity may also occur in Bornean smooth-tailed tree shrews. It has been suggested that the majority of mammals in northern Borneo breed over the summer months and likely pair formation occurs just prior to this period. (Kawamichi and Kawamichi, 1972; Kawamichi and Kawamichi, 1982; Kolar, 1972)

Nothing is known about reproduction in Bornean smooth-tailed tree shrews. Mammals in northern Borneo are believed to reproduce in the summer during which there is minimal precipitation. Generally, tree shrews tend to have 1 to 3 pairs of mammae and 1 to 3 young, the number varying among different species. The period of gestation in Scandentia ranges from 43 to 56 days. They reach their adult size at approximately three months of age and reach sexual maturity at approximately four months of age. (Kolar, 1972; Wade, 1958)

  • Breeding interval
    Breeding intervals in Bornean smooth-tailed tree shrews are not reported.
  • Breeding season
    The breeding season may be between April and August.
  • Range number of offspring
    1 to 3
  • Range gestation period
    43 to 56 days
  • Average gestation period
    50 days
  • Average time to independence
    3 months
  • Average age at sexual or reproductive maturity (female)
    4 months
  • Average age at sexual or reproductive maturity (male)
    4 months

Details of parental investment in Bornean smooth-tailed tree shrews are not reported in the literature. However, females are likely invest in parental care through gestation and lactation.

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

Lifespan/Longevity

Lifespan of Bornean smooth-tailed tree shrews is not reported in the literature. It may be similar to that of other tree shrew species, approximately 10 years. (Kolar, 1972)

  • Average lifespan
    Status: wild
    10 years
  • Average lifespan
    Status: captivity
    10 years

Behavior

Behavior of Bornean smooth-tailed tree shrews is not reported in the literature. Tree shrews are generally diurnal, live in pairs or are solitary, and are aggressive and territorial. Common tree shrews live in harems with one male and multiple females, suggesting another potential social structure for Bornean smooth-tailed tree shrews. Both members of the genus Dendrogale are recognized as mainly arboreal based on observations in the wild and skeletal morphology. The behavior of Bornean smooth-tailed tree shrews may be similar to the closely related northern smooth-tailed tree shrews, in which solitary individuals and pairs have been reported. Northern smooth-tailed tree shrews are active in the morning and afternoon and individuals show distress when they leave the cover of vegetation. (Endo, et al., 2003; Kawamichi and Kawamichi, 1972; Kawamichi and Kawamichi, 1982; Kolar, 1972; Timmins, et al., 2003)

Home Range

Nothing is known about home range size of Bornean smooth-tailed tree shrews. They are believed to be territorial and use olfactory cues to mark the range of their territories. Males and females of common tree shrews have individual territories that precisely overlap and are known to defend these territories from the same sex. Territories held by Bornean smooth-tailed tree shrews could also be potentially sex-specific. (Kawamichi and Kawamichi, 1982; Kolar, 1972)

Communication and Perception

Nothing is known about vocalizations of Bornean smooth-tailed tree shrews. Northern smooth-tailed tree shrews emmit short-pitched calls, particularly when climbing. These calls were heard when the animals were at high density in an area during the morning and were not heard at all in the afternoon. The calls emitted consisted of a repetition of 4 to 9 short, high-pitched notes with the pitch rising for the first couple of notes and then remaining more consistent for the last third of the call. It is possible that Bornean smooth-tailed tree shrews emit similar types of calls. (Timmins, et al., 2003)

Tree shrews are territorial and believed to use olfactory cues to mark specific spots along the edge of their territories to indicate their range. Tree shrews also emit species specific alarm calls to warn others of danger. Certain tree shrews such as common tree shrews emit chattering noises prior to copulation with females. All of these communication methods may be used by Bornean smooth-tailed tree shrews. (Emmons, 2000; Kawamichi and Kawamichi, 1982; Kolar, 1972; Timmins, et al., 2003; Walker, et al., 1975)

Food Habits

Nothing is known about the diet of Bornean smooth-tailed tree shrews. Tree shrews generally consume a generalist omnivore diet and have a simple digestive system with a caecum. They have been observed, in captivity and in the wild consuming a variety of arthropods, fruits, and small vertebrates. Captive specimens of the closely related northern smooth-tailed tree shrews accept both small pieces of meat and fruit and one wild specimen was observed eating a butterfly. (Kolar, 1972; Shanahan and Compton, 2000; Timmins, et al., 2003; Walker, et al., 1975)

  • Animal Foods
  • mammals
  • amphibians
  • insects
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Predation

Predation on Bornean smooth-tailed tree shrews is not reported in the literature. Other species of tree shrews may be preyed on by a variety of mammalian, reptilian, and avian predators. Reptiles and birds of prey are thought to be the greatest threat. They avoid predation by avoiding detection by predators. This avoidance of detection is aided by their small body size and cryptic coloring. Tree shrews also produce species specific alarm calls. Likely predators on the island of Borneo are listed below. (Brodie and Giordano, 2013; Emmons, 2000)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The ecosystem roles of Bornean smooth-tailed tree shrews are poorly understood. There is some evidence that other tree shrews may play an important role in seed dispersal due to the speed and the simplicity of their digestive systems. Bornean smooth-tailed tree shrews may also play a role in the population control of insects, a primary component of their diet. Tree shrews such as common tree shrews are also known to be hosts for a variety of nematode and cestode parasites, which may also be true for Bornean smooth-tailed tree shrews. (Betterton, 1979; Kolar, 1972; Shanahan and Compton, 2000)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

There are no known positive effects of Bornean smooth-tailed tree shrews on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Bornean smooth-tailed tree shrews on humans.

Conservation Status

Bornean smooth-tailed tree shrews have not been observed since the early 1970s and several trapping efforts between 1989 and 1991 have proved unsuccessful. For this reason the species has been classified as Data Deficient by the IUCN. It is thought that the population is in decline, potentially due to habitat loss occurring at low elevations throughout Borneo caused by logging for agriculture expansion and establishment of non-tree plantations. With further data IUCN may change the classification of this species to Near Threatened or higher. Current conservation efforts for this species are taking place at Crocker Range National Park in Sabah, Borneo. CITES categorizes the entire tree shrew order Scandentia in Appendix II, which means that, while these species are not on the verge of extinction, their trade and use must be regulated to ensure their survival. (CITES, 2014; Han and Stuebing, 2008)

Contributors

Madeline Bernuetz (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

acoustic

uses sound to communicate

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

cryptic

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.

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

island endemic

animals that live only on an island or set of islands.

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

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

solitary

lives alone

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.

References

Betterton, C. 1979. The intestinal helminths of small mammals in the Malaysian tropical rain forest: Patterns of parasitism with respect to host ecology. International Journal for Parasitology, 9(4): 313-320.

Brodie, J., A. Giordano. 2013. Lack of trophic release with large mammal predators and prey in Borneo. Biological Conservation, 163: 58-67.

CITES, 2014. "Appendices I, II and III" (On-line). Accessed October 27, 2014 at http://www.cites.org/eng/app/appendices.php.

Emmons, L. 2000. Tupai: A field study of Bornean treeshrews. Berkeley, CA: University of California Press.

Endo, H., T. Hikida, M. Motokawa, L. Chou, K. Fukuta, B. Stafford. 2003. Morphological adaptation of the skull for various behaviours in the tree shrews. Journal of Veterinary Medical Science, 65(8): 873-879.

Han, K., R. Stuebing. 2008. "Dendrogale melanura" (On-line). The IUCN Red List of Threatened Species. Accessed October 27, 2014 at www.iucnredlist.org.

Kawamichi, T., M. Kawamichi. 1982. Social system and independence of offspring in tree shrews. Primates, 23(2): 189-205.

Kawamichi, T., M. Kawamichi. 1972. Spatial organization and territory of tree shrews. Animal Behaviour, 27: 381-393.

Kolar, K. 1972. Tree Shrews and Prosimians. Pp. 270-277 in H Grzimek, ed. Grzimek's Animal Life Encyclopedia. New York, NY: Van Nostrand Reinhold Company.

Roberts, T., H. Lanier, E. Sargis, L. Olson. 2011. Molecular phylogeny of treeshrews (Mammalia: Scandentia) and the timescale of diversification in Southeast Asia. Molecular Phylogenetics and Evolution, 60(3): 358-372.

Sargis, E. 2001. A preliminary qualitative analysis of the axial skeleton of tupaiids (Mammalia Scandentia): Functional morphology and phylogenetic implications. Journal of Zoology, 253(4): 473-483.

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

Thomas, O. 1892. On some new Mammalia from the East-Indian Archipelago. Pp. 104-109 in Cited in K. Helgen, D Wilson, D Reeder, eds. Mammal Species of the World: a Taxonomic and Geographic Reference. Baltimore, Md: Johns Hopkins University Press.

Timmins, R., J. Duckworth, C. Robson, J. Walston. 2003. Distribution, status and ecology of the mainland slender‐tailed treeshrew Dendrogale murina. Mammal Review, 33(3-4): 272-283.

Wade, P. 1958. Breeding season among mammals in the lowland rain-forest of north Borneo. Journal of Mammalogy, 39(3): 429-433.

Walker, E., F. Warnick, S. Hamlet, K. Lange, M. Davis, H. Uible, P. Wright. 1975. Primates: Family: Tupaiidae. Pp. 395-400 in J Paradiso, ed. Mammals of the World. Baltimore, Md and London, UK: Johns Hopkins University Press.

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