Indri (Indri indri)

French: Indri À Queue Courte
Spanish: Indri Colicorto
GenusIndri (1)
SizeHead-and-body length: 64 – 72 cm (2)
Tail length: 4 – 5 cm (2)
Weight6 – 9.5 kg (2)
Top facts

Classified as Endangered (EN) on the IUCN Red List 2007 (1) and listed on Appendix 1 of CITES (3).

Indris are considered to be the largest of all of the lemurs, and are the only lemurs with vestigial tails. They have dense, silky black and white fur, with their patterns varying between populations on the island (4). Indris at the northern edge of the range tend to be darker, while those at the southern edge are usually lighter in colour. Their ears are black and tufted, and they have long muzzles, long slender legs and short arms (5). They are arboreal, with fantastic adaptations to allow them to climb trees and leap from one to another. Their powerful legs are about one third longer than their arms, and are able to propel them through the forest canopy in an upright position over distances of up to ten metres (4). The hands and feet are large and adapted for climbing trees and running along the forest floor, with small opposable thumbs, and large opposable big toes, which are useful for grabbing and handling things. The other toes are held together by webbing and work as one unit (5). The females are often larger in size than the males, and look very similar in appearance, as do the juveniles (4).

This species is endemic to Madagascar, a large island off the coast of east Africa (4). In the 1900s it was common throughout Madagascar but now the indri is only found in the eastern side of the island in the rainforests, from Mangoro River north to Sambava (5).

Inhabits montane and coastal rainforest from sea level to 1800 meters (6), but most typical of montane forest (2).

Indris are active during the day and are most at home in the trees, where they feed on leaves, flowers and fruit, but they do occasionally descend to the forest floor to cross small treeless areas or to eat soil (4) (6). On the ground they cannot walk on all fours and so move around on their back legs, standing upright and holding their arms outstretched for balance, skipping in a unique fashion through the forest (6).

These primates are social animals, living in family groups of two to five individuals, consisting of two adults and their offspring (6) (7). The adult female is dominant to the male. Females are often larger in size as they need to forage for more food than the male to feed themselves and their young (6). The male’s role is to defend the territory, and mark the boundaries with urine and secretions from its glands in the muzzle (5) (7). The indri has a characteristic call, consisting of a series of howls, which serve to unite groups, express territoriality, and convey information about age, sex and reproductive ability (6).

Breeding is seasonal, followed by a gestation period of more than five months. The female only gives birth to single offspring at a time, which develop more rapidly than the young of comparable sized primates (4). The young are born with the same colouration and features as the adult indris and are carried across the belly and later on the females back (6). Infant mortality is high, with 50 percent of infants dying before they are two years old from falls, injuries or illnesses, and sexual maturity comes late, after nine years for females (4). The fact that females only reproduce once every two to three years and that there are high infant mortality rates, adds to their population problem; their relatively slow breeding cycles cannot compete with their declining numbers (6).

The indri is one of the most endangered species of lemur on Madagascar, and one of the most threatened primates in the world (4). They live by the coast, where forests have become so fragmented that they are almost too small to sustain viable populations (6). The main threat is slash-and-burn agriculture, a practice that continues even in protected areas (7). Forests are also cut down for fuel and timber as human populations increase (5). Hunting of the indri is a taboo in many areas on the island, so this species does not suffer as much as other lemurs from trapping, although sometimes it is killed for food (5) (7). Despite this, the indri is a seriously endangered species and will almost certainly face extinction in the next 100 years if conservation efforts do not succeed (4).

The indri has never been bred successfully in captivity (7). Protection of their natural habitat is therefore imperative to ensure that they are not lost forever (6) (7). Unfortunately there is no easy answer to Madagascar’s conservation problems. Despite the indri being endangered, Madagascar’s increasing human population needs space and resources and inevitably this erodes natural habitats (4). This problem is made worse because Madagascar is an island; this therefore limits the area that men and wildlife can expand into (6). Conservation plans have designated some areas of the island to be protected from deforestation, but there is evidence that forest clearing continues inside the parks (5) (7). It would be sad indeed to see the indri populations, once so prevalent, dwindle away to nothing (6).

For further information on this species see: 

Authenticated (05/03/2006) by Matt Richardson, independent primatologist and writer.

  1. IUCN Red List (March, 2008)
  2. Richardson, M. (2006) Pers. comm.
  3. CITES (October, 2003)
  4. Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
  5. Animal Info (March, 2008)
  6. Dunbar, R. and Barrett, L. (2000) Cousins, our primate relatives. BBC Worldwide Ltd, London.
  7. Mittermeier, W., Konstant, R., Nicoll, M.E. and Langrand, O. (1992) Lemurs of Madagascar: An Action Plan for their Conservation. IUCN, Gland, Switzerland.