Animal Info - Indri

(Other Names: Amboanala, Babakoto, Endrina, Indri à Queue Courte, Indri Colicorto, Indris, Indrina)

Indri indri

Status: Endangered

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Weight, Habitat, Age to Maturity, Gestation Period, Birth Season, Birth Rate, Early Development, Diet, Behavior, Social Organization, Density and Range, Minimum Viable Population)
5. References

Profile

Pictures: Indri #1 (17 Kb JPEG); Indri #2 (33 Kb JPEG); Indri #3 (60 Kb JPEG)

The indri is a large, distinctive lemur with a very short tail. Its pelage is very dense and the coloration a mixture of black and white. There is considerable variation in the mixture of black and white throughout the species' range. The indri has a head and body length of more than 60 cm (24") and a tail length of only about 5 cm (about 2"). It weighs 6 - 7.5 kg (13 - 17 lb).

The indri's diet consists largely of leaves, flowers and fruit. It is primarily arboreal and diurnal. It moves through the canopy with spectacular bounds of up to 10 m (33') between vertical branches and trunks. Prior to dusk, a group settles in a sleep tree, 10 - 30 m (33 - 100') off the ground. Foraging can take place at all levels within the canopy. Occasionally, the animals descend to the forest floor to eat soil. Group size varies between 2 - 6, and normally comprises an adult pair with dependent offspring of varying ages. Within the pair, the female tends to be dominant and has priority at food resources. These family groups occupy ranges which are proclaimed by the indri’s characteristic eerie wailing songs (which are answered from as far as 3 km (2 mi) away). The songs may help maintain spacing between groups of indri, leading to a relatively small degree of overlap between the home ranges of neighboring groups.

In the early 1900's, the indri was so common that one traveler reported that no one could travel from Tamatave to Antanarivo without often hearing its cries. By the 1960's its abundance was decreasing due to deforestation. In the 1990's it was thought to occur in the central-eastern and northeastern rain forests of Madagascar from sea level to around 1500 m (4900'). Its range extends from the Mangoro River in the south to the area just southwest of Andapa in the north.

The indri is severely threatened by deforestation of its habitat for fuel, logging and slash-and-burn agriculture. Even forests lying within the bounds of protected areas continue to be felled and disturbed. Indris are not hunted by the local people because of taboos ("fady"). However, there are reports of immigrants from other tribal groups and even some foreign immigrants hunting indri.

Tidbits

*** The indri is the largest lemur.

*** The Betsimisaraka tribal name for the indri, "babakoto," means "Ancestor of Man" (Garbutt 1999).

*** In many areas, local taboos ("fady") protect the indri against hunting.

*** Before deforestation occurred, a separate troop of indris occupied almost every ridge in Madagascar's eastern forests (IUCN 1966).

Status and Trends

IUCN Status:

1960's: Vulnerable
1970's - 1994: Endangered
1996 - 2004: Endangered (Criteria: A1c+2c) (IUCN 2004)

Countries Where the Indri Is Currently Found:

2004: Occurs in Madagascar (IUCN 2004).

Population Estimates:

[Note: Figures given are for wild populations only.]

WORLD (Madagascar)
- 1994: There are no population figures available, but a reasonable order of magnitude estimate would be 1000 - 10,000 (Mittermeier et al. 1994)

History of Distribution:

In the early 1900's, the indri was so common that one traveler reported that no one could travel from Tamatave to Antanarivo without often hearing its cries (Curry-Lindahl 1972). Up to the 1960's it was known from the forests of the eastern volcanic mountain chain of Madagascar, between the Bay of Antongil in the north and the River Masora in the south (IUCN 1966). At that time its abundance was decreasing due to deforestation.

In the 1990's it was thought to occur in the central-eastern and northeastern rain forests of Madagascar from sea level to around 1500 m (4900'), although elevations below 1000 m (3300') appear to be preferred. Its range extends from the Mangoro River in the south to the area just southwest of Andapa in the north, but does not reach the Marojejy Massif, nor does its range extend into the Masoala Peninsula in the northeast. (Garbutt 1999)

Distribution Map (42 Kb JPEG)

Threats and Reasons for Decline:

Data on Biology and Ecology

Weight:

The indri has a head and body length of 60 - 67 cm (24 - 26") and a tail length of only 4 - 5 cm (about 2"). It weighs 6 - 7.5 kg (13 - 17 lb). (Garbutt 1999)

Habitat:

The indri is found in primary and secondary lowland and mid-altitude rain forest from sea level to about 1500 m (4900'), although elevations below 1000 m (3300') appear to be preferred (Garbutt 1999).

The indri lives in both the Madagascar & Indian Ocean Islands Biodiversity Hotspot (Cons. Intl. 2005) as well as the Madagascar Moist Forests Global 200 Ecoregion. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)

Age to Maturity:

Indris do not reach sexual maturity until 7 - 9 years of age (Garbutt 1999).

Gestation Period:

120 - 150 days (Garbutt 1999).

Birth Season:

Mating generally occurs between December and March. Births occur in May or June, but sometimes as late as August. (Garbutt 1999)

Birth Rate:

A single young is born. Females are probably only capable of giving birth every 2^nd or 3^rd year. (Garbutt 1999)

Early Development:

Initially, the infant indri is carried on its mother’s lower stomach, but it transfers to ride on her back after 4 months. The young indri is capable of moving independently at 8 months, but it remains in close proximity to its mother until well into its second year. Mother and infant always sleep together for the first year, but afterwards do so only sporadically. (Garbutt 1999)

Diet:

The indri's diet consists largely of young leaves and leaf buds, but also some flowers and both ripe and unripe fruits. (Garbutt 1999)

Behavior:

The indri is primarily arboreal and is probably the most strictly diurnal of lemurs (although it is known to call at night). It is active for 5 - 11 of the daylight hours, depending on the season and weather conditions. The indri’s daily range of movement is 300 - 700 m (1000 - 2300'). It moves through the canopy with spectacular bounds of up to 10 m (33') between vertical branches and trunks. Prior to dusk, a group settles in a sleep tree, 10 - 30 m (33 - 100') off the ground. Females generally sleep in contact with their infants or subadult offspring, but males typically sleep 2 - 50 m (7 - 160') away. If a male approaches too closely to a sleeping female, he often gets cuffed. Foraging can take place at all levels within the canopy. Bouts of feeding are punctuated by periods of rest, before the group moves on to the next feeding site. Occasionally, the animals descend to the forest floor to eat soil. This may help detoxify poisons accumulated from the leaves they feed on or provide some vital trace elements. (Garbutt 1999)

Indri, sifakas (for example, diademed sifaka and golden-crowned sifaka) and woolly lemurs have body plans that support a highly specialized mode of locomotion: vertical-clinging-and-leaping. Powerful legs, about 1/3 longer than their arms, propel them between trees while allowing them to keep an upright body posture. (Macdonald 2001)

Social Organization:

Group size varies between 2 - 6, and normally comprises an adult pair with dependent offspring of varying ages. Within the pair, the female tends to be dominant and has priority at food resources. These family groups occupy ranges which are proclaimed by the indri’s characteristic eerie wailing songs (which are answered from as far as 3 km (2 mi) away). The songs may help maintain spacing between groups of indri, leading to a relatively small degree of overlap between the home ranges of neighboring groups. Smaller ranges appear typical of isolated pockets of forest, while larger ranges are associated with more expansive undisturbed tracts of forest. (Mittermeier et al. 1994, Garbutt 1999)

Density and Range:

The following approximate densities have been observed (Britt et al. 1999):

Sahivo: 3 - 6 individuals/sq km (8 - 16 individuals/sq mi)

Antanamalaza: 4 - 12 individuals/sq km (10 - 31 individuals/sq mi)

Betampona: 4.5 - 6.7 individuals/sq km (12 - 17 individuals/sq mi)

Analamazoatra: 8 - 16 individuals/sq km (21 - 42 individuals/sq mi)

Range:

Home ranges of indri groups in one study averaged about 18 hectares (45 acres). A core area within the home range constitutes a territory which is defended against other groups. (Mittermeier et al. 1994)

Groups occupy ranges of 8 - 30 hectares (20 - 75 acres) (Garbutt 1999)

Minimum Viable Population:

Minimum viable population density: 3 individuals/sq km (7.8 individuals/sq mi) (Silva & Downing 1994).

References

Britt et al. 1999, Burton & Pearson 1987, Cons. Intl. 2005, Curry-Lindahl 1972, Garbutt 1999, IUCN 1966, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, Macdonald 1984, Macdonald 2001, Mittermeier et al. 1994, Nowak & Paradiso 1983, Olson & Dinerstein 1998, Olson & Dinerstein 1999, Silva & Downing 1994

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Last modified: June 1, 2005;