Animal Diversity Web

Ge­o­graphic Range

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

• Biogeographic Regions
• ethiopian
  • native

• Other Geographic Terms
• island endemic

Habi­tat

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

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• mountains

• 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.

• Other Physical Features
• endothermic
• bilateral symmetry

• 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.

• Mating System
• 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.

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• viviparous

• 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.

• Key Behaviors
• arboreal
• saltatorial
• diurnal
• motile
• sedentary
• territorial
• social
• dominance hierarchies

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.

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Other Communication Modes
• scent marks

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

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

• Primary Diet
• herbivore
  • frugivore

• 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.

• Positive Impacts
• ecotourism

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.

• IUCN Red List

  Endangered
  More information

• IUCN Red List

  Endangered
  More information

• US Federal List

  Endangered

• CITES

  Appendix I

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.

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.