Indri indriindri

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Geographic Range

Indris, Indri indri, are found in the northeastern part of Madagascar. (Nowak, 1983)

Habitat

Indris reside in coastal and montane rainforest from sea level to 1,800 m in northeastern Madagascar.

  • Range elevation
    0 to 1,800 m
    0.00 to ft

Physical Description

Indri indri is considered to be the largest of the surviving lemur species. Individuals weigh between 7 and 10 kg when fully mature. The length of the head and body is 60 to 90 cm. The tail is vestigial and is only 5 to 6 cm long. Indris have prominent tufted ears, a long muzzle, long slender legs, short arms, and silky pelage. Individuals have variable pelage coloration, with patterns of grays, browns, blacks, and whites found in this species. The ears are always black, and the face, ears, shoulders, back, and arms are usually black, but may vary in color. Whitish patches may occur on the crown, neck or flanks, but may also occur on the rear and outside surfaces of the arms and legs. Individuals at the northern end of their range tend to be darker, whereas those at the southern end tend to be lighter in color.

Indris also have large hands and feet. The thumb is small and slightly opposable, but the big toe is large and very opposable. The other toes are held together by webbing and work as a unit.

  • Range mass
    7 to 10 kg
    15.42 to 22.03 lb

Reproduction

Data on the mating system of these animals have not been reported. However, Indris appear to live in family units, consisting of a mated pair and their offspring. This indicates that these mammals are likely to be monogamous.

Indris breed seasonally, with individual females producing one offspring every 2 to 3 years. Births occur in May after a gestation of 120 to 150 days. Young are weaned at about 6 months of age, although they stay close to their mothers for about two years. Females become reproductively mature between 7 and 9 years of age.

  • Breeding interval
    Indris breed once every two to three years.
  • Breeding season
    Births occur in December in the northern part of the range, and in May in the southern portion of the range.
  • Average number of offspring
    1
  • Range gestation period
    120 to 150 days
  • Average weaning age
    6 months
  • Average time to independence
    8 months
  • Range age at sexual or reproductive maturity (female)
    7 to 9 years

The young ride on the mother's belly up to the age of 4 to 5 months, and then they move to the mother's back. Weaning takes place at about 6 months. At 8 months of age, the young are moving independently, although they stay close to their mothers until after age 2. The role of males in parental care has not been reported.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female
  • post-independence association with parents
  • extended period of juvenile learning

Lifespan/Longevity

The lifespan of this species has not been reported. However, other lemurs may live betweeen 25 and 40 years in captivity. Indris are probably similar.

Behavior

Indris are diurnal and arboreal. The amount of time of activity varies from season to season, depending on the amount of daylight available. Between 30 and 60% of its activities are associated with feeding. Indris move by vertical leaps from tree to tree. When they do descend to the ground, they move by jumping and holding their arms above their head.

Indris live in groups of 3 to 5 individuals, consisting of 2 adults and their offspring. The adult female is dominant to the adult male. The group ranges from 300 to 700 m daily. Groups space themselves through loud, wailing calls that not only determine territories, but also unite groups. Territorial defense is by adult males. They mark territories with urine and also use gland secretions from the muzzle.

Communication and Perception

As in other diurnal primates, visual signals are used in communication. Body posture and facial expressions are probably included in their visual signals. Indris are vocal, and use various calls to communicate. In addition, because they are social, tactile communication is probably important, especially between members of a family. Males use scent cues in marking familial territories.

Food Habits

Indris are vegetarian. They feed mainly on the fruits, leaves, and flowers of trees. Sometimes they feed on ground vegetation.

  • Plant Foods
  • leaves
  • fruit
  • flowers

Predation

Details on predation of these mammals are not available in the literature. However, it is likely that large birds, or heavier carnivorous mammals may prey upon them.

Ecosystem Roles

As frugivores, indris probably help to disperse seeds. To the extent that they serve as prey for other animals, they may affect local food webs.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Indris are interesting animals and may be important in attracting ecotourists to Madagascar.

Conservation Status

Indri indri is an endangered species. It is endemic to Madagascar, and it is losing its rainforest habitat for fuel, timber, and slash-and-burn agriculture. Destruction is occurring even in protected areas. Hunting of indris is taboo to the local people, although occasionally one is killed for food. Indris are not typically kept in captivity. Previous attempts to do so have been unsuccessful.

Other Comments

The loud call of the indri is produced by a laryngeal air sac. It can be heard by humans from as far away as 1.2 miles.

The name indri means "there it is." It arose from a misunderstanding between the local people and the person who 'discovered' it. The native name for the animal was actually babakoto or ambalana.

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Barbara Lundrigan (author), Michigan State University, Crystal Katopol (author), Michigan State University.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

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

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

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).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

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

social

associates with others of its species; forms social groups.

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

Mittermeier, R. 1994. Lemurs of Madagascar. Washington DC.: Conservation International.

Morris, D. 1965. The Mammals: A Guide to the Living Species. New York: Harper and Row Publishers.

Nowak, R. 1983. Walker's Mammals of the World, 4th edition. V-1. Baltimore: The Johns Hopkins University Press.