Primate of the Week

Indri or Babakoto

Indri indri

Indri Facts

Source: Lemurs of Madagascar
(with permission from Conservation International)

Identification

The indri is generally considered the largest-bodied living lemur, averaging about 6-7 kg in body weight or possibly more, but Propithecus d. diadema is a close competitor. It is a typical vertical clinger and leaper, with long hind limbs compared to the trunk and forelimbs, and a preference for postures in which the trunk is held vertically. The combined length of its head and body averages slightly over 60 cm, but the tail is vestigial and only abut 5 cm long. Pelage coloration is highly variable.

The fur is predominantly black, with whitish patches that may be restricted to the crown, neck or flanks, but which may also occur on the rear and outside surfaces of the fore- and hindlimbs. Such paler areas may be tinged with gray or gold. The face is black and may be variably framed with paler fur. The ears are black, modestly tufted, and highly visible. Darker individuals tend to be found at the northern end of the species' range, lighter ones towards the south. The indri is easily located and identified by its eerie, wailing loud song. It is also unlikely to be mistaken for any other lemur species living in its range, except where it abuts with the similarly proportioned and darkish-colored Propithecus diadema edwardsi . However, the indri is easily distinguished from this animal and the lighter colored P. diadema diadema, with which it is broadly sympatric, by its prominent ears, long muzzle and especially by its vestigial tail, which contrasts strongly with the long tail of the Propithecus species.
Photo by Anthony C. Brewer

Geographic Range

Illustration by Stephen D. Nash

This species inhabits the eastern rain forests of Madagascar, from the Mangoro River north to near Sambava, but excluding the Masoala Peninsula (Petter et al., 1977; Tattersall, 1982). Its most northerly occurrence appears to be in the reserve of Anjanaharibe-Sud, just to the east of Andapa (Nicoll and Langrand, 1989). Whether this range is even approximately continuous is not known, and it has certainly shrunk in recent decades. Subfossil evidence indicates that the indri once occurred in the interior of Madagascar as far west as the Itasy Massif (Tattersall, 1982), and to the north on the Ankarana Massif (W. Jungers and E. Simons, pers. comm.). Its altitudinal range is up to 1500 m (Petter et al., 1977).

Natural History

The indri has been studied in the wild by J. Pollock (1975, 1977, 1979) in the forests of Analamazaotra near perinet (=Andasibe). It lives in groups of from three to five individuals, normally consisting of an adult pair and their offspring (Pollock, 1979). The female appears to be the dominant member of the pair, normally feeding higher in the trees than the male and having priority access to food sources. Its diet consists of leaves, flowers and fruit, which vary in their proportions according to season, and it also occasionally descends to the ground to eat earth. Home ranges of groups studied at Analamazaotra averaged about 18 ha, with day ranges of 300 to 700 m. Spacing between groups may be conditioned by the famous loud morning calls (which are answered from as far as 3 km away), accounting for a relatively small degree of range overlap between neighboring groups. Densities at Analamazaotra ranged from 9-16 individuals per square kilometer, both in primary and degraded forests (Pollock, 1975).

Illustration by Stephen D. Nash

The indri seems to be the most strictly diurnal of all lemurs, its activity period occupying from 5-11 daylight hours, according to season (Pollock, 1979). It sleeps from 10-30 m above the ground, and no more than two animals ever sleep in contact with one another; distances between group members can be 100 m or more (Pollock, 1975).

Reproduction is highly seasonal, with births occurring in May after a gestation period of 120-150 days. Infants ride on the mother's ventrum up to the age of four to five months, then transfer to the back. By eight months they are moving independently, but they stay close to the mother until well into their second year (Pollock, 1975). Reproductive maturity is reached between seven and nine years of age (Pollock, 1977, 1984).
Conservation Status

The indri is threatened by loss of its eastern rain forest habitat for fuel, timber and slash-and-burn agriculture (Pollock, 1984), with destruction occurring even in protected areas. Although with destruction occurring even in protected areas. Although other lemur species are hunted within the indri's range, hunting of the indri itself is considered taboo by many local people. Nonetheless, there are reports that it is occassionally killed for food, especially by Chinese living in Madagascar. A small scandal erupted in 1984, when it came to light that Chinese workers on the road from Antananarivo to Tamatave (=Toamasina) were apparently buying indris as a delicacy.

The species is found in the Mantady and Verezanantsoro National Parks, the Betampona and Zahamena Nature Reserves, and the Ambatovaky, Analamazaotra and Anjanaharibe-Sud Special Reserves (Nicoll and Langrand, 1989; Harcourt and Thornback, 1990; Mittermeier et al., 1992). There are no population figures available, but a reasonable order of magnitude estimate would be 1,000-10,000 (Mittermeier et al., 1992). There are no indri in captivity anywhere in the world, and previous attempts to keep them were notably unsuccessful.

In recognition of the indri's taxonomic uniqueness, relatively small and probably discontinuous population, and the threats to its existence, even in protected areas, it was given the Highest Priority rating (6) in the IUCN/SSC Primate Specialist Group's Lemurs of Madagascar: An Action Plan for their Conservation (Mittermeier et al., 1992). Using the latest IUCN Red List criteria, we place this species in the Endangered category.

Source of Information:
Mittermeier, R. A., Tattersall, I., Konstant, W. R., Meyers, D. M., Mast, R. B. 1994. Lemurs of Madagascar. Conservation International, Washington, D.C.

References
Harcourt, C. and J. Thornback 1990. Lemurs of Madagascar and the Comoros. The IUCN Red Data Book, compiled by C. Harcourt. IUCN, Gland, Switzerland and Cambridge, U.K.
Mittermeier, R.A., W.R. Konstant, M.E. Nicoll and O. Langrand 1992. Lemurs of Madagascar: An Action Plan for their Conservation. 1993-1999. IUCN/SSC Primate Specialist Group, Gland, Switzerland.
Nicoll, M.E. and O. Langrand 1989. Madagascar: Revue de la Conservation et des Aires Protegees. World Wide Fund for Nature, gland, Switzerland, xvii + 374 pp.
Petter, J.-J., R. Albignac and Y. Rumpler 1977. Mammiferes: lemuriens (Primates prosimiens). Faune de Madagascar No. 44. ORSTOM-CNRS, Paris.
Pollock, J. I. 1975. Field observations on Indri indri: A preliminary report. Pp. 287- 311 in : I. Tattersall and R. w. Sussman (eds.), Lemur Biology. Plenum Press, New York.
Pollock, J. I. 1977. The ecology and sociology of feeding in Indri indri. Pp. 37-69 in: T. Clutton-Brock, (ed.), Primate Ecology: Studies of Feeding and Ranging Behavior in Lemurs, Monkeys and Apes. Academic Press, London.
Pollock, J. I. 1979. Spatial distribution and ranging behavior in lemurs. Pp. 359-409 in: G.A. Doyle and R. D. Martin (eds.), The Study of Prosimian Behavior. Academic Press, New York.
Pollock, J. I. 1984. Preliminary report on a mission to Madagascar by Dr. J.I. Pollock in August and September 1984. Unpublished report to WWF-US Primate Program.
Tattersall, I. 1982. The Primates of Madagascar. Columbia University Press, New York.

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