Indri indri (Gmelin, 1788)

Order PRIMATES

Family INDRIIDAE

SUMMARY

Indri is the largest of the living lemurs. It is now confined to a stretch of approximately 500 kms of the north and central eastern rain forest, a much smaller area than it was found in even a few decades ago. Population figures are not known, but it is not thought to occur at high densities anywhere. It is a diurnal, territorial, family-living species, which feeds principally on leaves and fruit. The species has been the subject of a 15 month study in the forest of Analamazaotra. Its numbers are declining as the eastern forest is destroyed for timber, fuel and agricultural land. Indri indri is found in at least four protected areas, one of which was created specifically for its protection. None is in captivity. Listed in Appendix 1 of CITES, Class A of the African Convention and protected by Malagasy law.

DISTRIBUTION

Now confined to the eastern rain forest from the Mangoro River northwards to near the latitude of Sambava, but excluding the Masoala Peninsula (Petter et al, 1977; Tattersall, 1982). Other authors consider that Indri extends only to around Maroantsetra (Petter and Petter, 1971) or just north of there to the Antanambalana River (Petter and Petter-Rousseaux, 1979). However, it has recently (1989) been reported in the Special Reserve of Anjanharibe-Sud (Nicoll and Langrand, 1989). Tattersall, in 1982, considered that Indri was rare or even extirpated from the more northern extremities of its range. Whatever the present distribution, it has certainly been considerably reduced even within the past few decades (Petter et al, 1977). As recently as 1939, it was recorded by Lamberton as far south as Maranjary (noted in Tattersall, 1982). Subfossil evidence indicates that it used to occur in the interior of Madagascar, at least as far west as the Itasy Massif (Tattersall, 1982).

POPULATION

Numbers are unknown and population density varies widely making it difficult to estimate even an approximate figure of the number of Indri in Madagascar (Pollock, 1975). In 1972 in the forest of Analamazaotra and those of Fierenana and Vohidrazana nearby, Pollock estimated densities of 9-16 individuals per sq. km (Pollock, 1975). He found no noticeable difference in the density of Indri between those in primary forest and those in selectively degraded forest, however his sample size was small (Pollock, 1975). Petter and Peyrieras (1974) found only one group (presumably three or four animals) per sq. km in undisturbed rain forest near Maroantsetra and they suggested that the higher densities in Analamazaotra (Perinet) were due to human interference.

HABITAT AND ECOLOGY

Found in the eastern rain forest from sea level to 1500 m (Petter et al, 1977). Indri is one of the few lemurs that has been studied for more than a few months at a time. Pollock (1975, 1977, 1979) observed several groups in the forest of Analamazaotra for 15 months, from June 1972 to August 1973. He found, as Petter had reported earlier (Petter, 1962), that Indri lives in groups of between two and five individuals, these are usually an adult pair and their offspring. The two main groups studies, by Pollock (1979) occupied defended territories of approximately 18 ha with little overlap between ranges. Petter and Peyrieras (1974) suggested a home range size for each group of 100 ha, but this was based on plotting the locations of calling groups rather than on direct observation. Loud morning calls advertise the presence of the groups within their ranges and these calls may be answered from as far as 3 km away (Petter and Peyriéras, 1974; Pollock, 1975, 1979, 1986). The Indris may also call at night (Oliver and O'Connor, 1980). Arboreal locomotion is principally by leaping from one vertical trunk to another. The daily distance traveled by the two groups in Analamazaotra was between 300 and 700 m (Pollock, 1979). Indri indri is strictly diurnal and has an activity period lasting 5-11 hour depending on season and weather (Pollock, 1975, 1979b). It sleeps in trees from 10-30 m above the ground, no more than two animals ever sleep in contact and distances between individuals can be 100 m or more (Pollock, 1975).

Indri feed on leaves (mostly young ones), flowers and fruits with feeding continuing throughout the day, reaching a peak at midday (Pollock, 1979). Females and very young individuals have priority of access to food (Pollock, 1977, 1979b). When certain plant species flushed into leaf, flowered or bore fruit, Indri groups made an early progression to these trees and then fed in them continuously for one to three hours. This was followed, in the early afternoon, by a series of short feeding bouts on a diverse array of plant species and usually ended in a central sleeping area (Pollock, 1979). Alternatively, when no concentrated source of food was present, the Indri ranged in a less predictable fashion with small feeding progressions scattered throughout the day (Pollock, 1979). All levels of the forest are used, including the ground to which the animals descend to eat earth exposed by upturned tree trunks (Pollock, 1979).

Infants are born in May after a gestation of 120-150 days and are carried on the front of the female until they are four or five months old, after which they transfer to ride on her back (Pollock, 1975). They move independently by the age of eight months but remain feeding closer to their mother than to any other group member into their second year (Pollock, 1975). The infants sleep with their mothers every night for the first year of life, but do so irregularly thereafter (Pollock, 1975). Females probably give birth no more than once every two or three years and reproductive maturity is not reached until between seven and nine years of age (Pollock, 1977, 1984).

THREATS

Indri indri is severely threatened by destruction of its habitat for fuel, timber and, particularly, local agricultural development (Pollock, 1984). This destruction continues even in the protected areas as none of these eastern reserves is adequately guarded or financed. For instance, in 1984 over 3 000 people were reported to be living in a central valley enclave of Zahamena and more than 2000 ha of the forest there had been destroyed (Rabemazara pers. comm. to Pollock, 1984b). There is also a risk that the north/south paths from this legal central enclave to villages outside the reserve will bisect the protected area, hunting already occurs along these paths (Nicoll and Langrand, 1989). Hunting of lemurs does occur, even in the protected areas, but it is not clear if the Indri is killed. To some of the local groups it is taboo to hunt this species. The Indri is certainly declining in numbers (Richard and Sussman, 1975, 1987). Its slow reproductive rate makes it more vulnerable to extinction.

CONSERVATION MEASURES

Indri are found in several reserves in Madagascar including Zahamena and Betampona Natural Reserves and the Special Reserves of Anjanharibe-Sud and Analamazaotra (Nicoll and Langrand, 1989). The Reserve at Analamazaotra (Perinet) was created in 1970 specifically for the protection of Indri (Petter and Peyrieras, 1974; Pollock, 1984b) and it is here that tourists can most easily see this species. However, the Reserve is small and has become isolated from previously contiguous forest blocks so it is of greater educational than conservation value (Pollock 1984b). Regular patrols of the Reserve are needed to protect it from encroachment and from hunters (Nicoll and Langrand, 1989). A local conservation group "Friends of the Reserve of Andasibe" has been created and it is suggested that this group could play a role in increasing local public awareness of the Special Reserve (Nicoll and Langrand, 1989). It has been proposed that a National Park be created in the region of Mantady just north of Analamazaotra and the management of the two areas could be combined (Nicoll and Langrand, 1989).

Indri is found in Zahamena Reserve, which is the largest protected area in the eastern rain forest, though it probably exists at a lower density there than in Analamazaotra (Raxworthy 1986). Members of an expedition to Zahamena in 1985 suggested that fire breaks and boundary trails be cut round the Reserve and that more people were needed to guard it adequately (Thompson et al, 1986; Raxworthy, 1986). That expedition financed a two kilometre fire break in the south-west of the Reserve (Raxworthy, 1986). Several guard stations are probably essential to effect adequate control of Zahamena, one or more of these are needed within the central enclave (Pollock, 1984b). It may be that a new demarcation of the Reserve, excluding the central human settlement, is necessary in order to create a viable protected area (Pollock, 1984b).

Pollock (1984b) reports that a few Indri are present in Betampona Nature Reserve but he suggests that there may not be sufficient numbers left to create a self-sustaining population within the isolated forest island which is all that remains of the Reserve. It is surrounded by extensive agricultural development. As for the other reserves, funds are needed to support permanent guards within the area and frequent patrolling of the reserve is needed (Pollock, 1984b). Though there is already a good network of paths, some extra ones are needed for a comprehensive coverage of the region (Pollock, 1984b).

Petter et al (1977) suggests that it may be possible to introduce Indri indri onto the island of Nosy Mangabe. However, the small size of the island (520 ha) makes it unlikely that it would support many of these large, territorial lemurs. An area around Mananara has been proposed as a Biosphere Reserve and this would protect the Indris found there (Nicoll and Langrand, 1989).

Surveys are needed to make accurate estimates of population numbers and to determine the true distribution of this species so that these data can be used as the basis for conservation management of the species. Participants at the St Catherine's Lemur Workshop in 1986 suggested that range-wide surveys of this species are needed as soon as possible.

It may be possible to try breeding Indri in captivity, perhaps at an Eaux et Fôret station within the range of the species but this would need full time monitoring from a highly qualified lemur specialist (St Catherine's Workshop, 1986). If breeding in captivity is to be attempted at all, it is suggested that the individuals taken into captivity are from doomed habitats that have no long term hope for survival (St Catherine's Workshop, 1986).

All species of Indriidae are listed in Appendix 1 of the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora. Trade in them, or their products, is subject to strict regulation and may not be carried out for primarily commercial purposes.

All Lemuroidea are listed in Class A of the African Convention, 1969. They may not therefore, be hunted, killed, captured or collected without the authorization of the highest competent authority, and then only if required in the national interest or for scientific purposes.

Though legally protected from capture or killing within Madagascar, enforcement of this is difficult in practice.

CAPTIVE BREEDING

Indri has never been successfully kept in captivity. One young individual was kept for more than a year at Ivoloina in Madagascar, but generally this species does not survive long when caged (Petter et al, 1977).

REMARKS

Indri indri is the largest of the living lemurs, weighing 7-10 kg or more (Pollock, 1984). Pelage coloration and pattern are highly variable, mostly black with some white, gray or brown (Tattersall, 1982; Jenkins, 1987). It is the only lemur species with virtually no tail. For a more detailed description see Tattersall (1982) or Jenkins (1987). Babakota, one of the Malagasy names for this species, means "the father of man" or "the ancestor" (Petter et al, 1977). Other local names for the Indri are amboanala and endrina (Tattersall, 1982).