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Nycticebus coucangslow loris

By Liz Ballenger

Geographic Range

Nycticebus coucang inhabits the rainforests of southeast Asia, Assam, Burma, Thailand, Indo-China, certain Malayan states and East Indian Islands.

Habitat

Slow lorises are arboreal primates, occupying the canopies of Malayan rainforest. They are almost never observed out of the treetops, although when they are on the ground, they move with a wavering trot.

Physical Description

Nycticebus coucang is a small primate, measuring between 300 and 380 mm for head and body. Individuals typically weigh less than 2 kg.

Slow lorises have a vestigial tail. The second digit on their hands is reduced in size, and the big toe on the hind foot is set well apart from the other toes, demonstrating great gripping power. As in all lorisoids, slow lorises have a long, curved claw on the second toe which sticks up and is used to scratch the skin. Lorises have more vertebrae in their backs, giving them a greater tree-climbing advantage since they can twist around above and below branches with wide range and extension of movement.

Slow lorises are covered with short, thick, woolly fur, which is found in a wide variety of colors and patterns. Generally, the color above is from light brownish gray to deep reddish brown, sometimes with a hoary effect produced by the tips of individual hairs. The color beneath ranges from white to buffy to grayish. There is usually a dark mid-line along the neck and back, and a light streak between the orbital rings.

This species produces a toxin from brachial glands on its arms, and a toothcomb on the lower jaw may help the loris transfer the toxin (see other comments).

  • Range mass
    2 (high) kg
    4.41 (high) lb
  • Average mass
    0 kg
    0.00 lb
  • Range length
    300 to 380 mm
    11.81 to 14.96 in
  • Average basal metabolic rate
    1.504 W
    AnAge

Reproduction

Although not well documented, the mating system of this species appears to be monogamous. Slow lorises are often found in family groups, and males, who are highly territorial, are not tollerant of one another.

Research indicates that slow lorises breed throughout the year. Generally, a female will have one offspring after a gestation of 191 days. Young weigh on average 52.4 g at birth, and are weaned at about 189 days old. Males become intolerant of offspring as they reach 18 months of age, and force the young to disperse. Females are capable of breeding at about 18 months of age, and males are at about 17 months.

  • Breeding interval
    Females may breed twice per year.
  • Breeding season
    These animals breed throughout the year.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    184 to 197 days
  • Average gestation period
    191 days
  • Average birth mass
    48.2 g
    1.70 oz
    AnAge
  • Range weaning age
    175 to 213 days
  • Average weaning age
    189.5 days
  • Average time to independence
    18 months
  • Average age at sexual or reproductive maturity (female)
    18 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    578 days
    AnAge
  • Range age at sexual or reproductive maturity (male)
    17 (low) months

The young will attach itself to its mothers fur (anywhere on the mother's body, depending on how the mother is travelling). The young then remain passengers until they are nearly as large as the mother. The role of the male in parental care has not been described.

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

Lifespan / Longevity

Nycticebus coucang may live as long as 26 years in captivity, and lifespans of 20 years are not uncommon.

Behavior

Slow lorises are mainly solitary and mark trees with their urine to avoid direct conflict with other individuals. This is done by urinating on their hands and wiping it onto tree trunks and branches. They are completely nocturnal and sleep during the day curled up in hollow trees, crevices, or simply along a branch. Despite their usual slow movements, slow lorises are quite capable of rapid locomotion, especially when disturbed or in search of food. They have been observed to make sharp twittering noises when annoyed.

Lorises may protect themselves and their young using a toxin (see Other Comments). Predators include cats, sun bears, and Paradoxurus.

Communication and Perception

Slow lorises have communication systems typical of prosimians. They use scent cues to communicate and to mark territories. They use vocalizations, including calls and whistles, to attract mates. Tactile communication in grooming and aggression are common. The role of visual signals in this species' communication has not been identified, but body postures and facial expressions are likely to be communicative.

Food Habits

Slow lorises are nocturnal predators and feed mainly on insects, bird eggs, and young birds or sleeping birds and mammals. They will readily eat fruits and other parts of plants, however. They move slowly toward their prey so as not to frighten it away, but once they are within striking range, lorises move quickly to subdue their prey. The grip of the slow loris's hind feet is so strong that it often gathers food hanging upside down using its front hands to capture and hold prey.

  • Animal Foods
  • birds
  • mammals
  • eggs
  • insects
  • Plant Foods
  • fruit

Predation

Lorises may protect themselves and their young using a toxin (see Other Comments). Predators include cats, sun bears, and Paradoxurus (palm civets).

Ecosystem Roles

As part of their general omnivory, these animals may help to structure local food webs.

Economic Importance for Humans

Economic Importance for Humans: Positive

Legends about the use of slow lorises in cures and as luck charms (see Other Comments below) established some economic importance of lorises to humans, especially natives. In addition, their fur has been used in garments in the recent past.

Economic Importance for Humans: Negative

Nycticebus coucang has no negative impact on human populations.

Conservation Status

Although slow lorises occupy a fairly broad geographic range, they are not common in these areas and are often out-competed by arboreal monkeys in areas where different species overlap. Since their secretive and nocturnal lifestyles make them difficult to observe, accurate population estimates in many areas are difficult to obtain. Other members of the genus are considered vulnerable or threatened by various agencies, and it is likely that with more research on N. coucang it may join these.

Other Comments

Natives have many strange superstitions and beliefs about the slow loris. Lorises or parts of them are claimed to have remarkable powers of good and evil. In addition, their fur is said to speed the healing of wounds; if a ship carries one as a mascot, it is never becalmed. Dead or alive, lorises were supposed to have power over the lives of human beings. The lorises themselves were believed to be unhappy because they were constantly seeing ghosts (which people believed is why they always bury their heads in their hands).

Captive studies have shown that this species produces a toxin, a polypeptide, from the brachial gland on the arm. The toxin is usually present, but sometimes it is inhibited by other substances secreted by the gland. When mixed with saliva, it repels at least some predators (it has been tested with a variety of cats, sun bears, and civets). Mothers cover their babies with saliva when they leave them, probably to repel predators. Nycticebus may also use biting as a way of delivering the toxin. The toxin apparently gets into the saliva when the animal licks its brachial glands. The narrow spaces between the teeth of the toothcomb in the lower jaw act as capillaries, drawing the saliva and toxin into whatever the animal is biting. While the activity and use of the toxin need to be examined in the field, native peoples of Indonesia regard Nycticebus as venomous (Alterman, 1995).

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Liz Ballenger (author), University of Michigan-Ann Arbor.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

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

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

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

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).

monogamous

Having one mate at a time.

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.

nocturnal

active during the night

omnivore

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

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

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.

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

Bourne, G.H. 1974. Primate odyssey. G.P. Putnam's Sons, New York.

Eimerl, S. and I. DeVore. 1965. The primates. Time Inc., New York.

Freeman, D. 1977. The love of monkeys and apes. Octopus Books, London.

Walker, E.P. 1964. Mammals of the world. John Hopkins Press, Baltimore, MD.

Alterman, L. 1995. Toxins and toothcombs: potential allospecific chemical defenses in Nyciticebus and Perodicticus. Pp. 413-424 in L Alterman, G Doyle, Y Izzard, eds. Creatures of the Dark. NY: Plenum Press.

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