Indri

Lore & Background

The indri is a diurnal tree-dweller related to the sifakas. It has a black and white coat and maintains an upright posture when climbing or clinging. It is a vertical clinger and leaper, using its long, muscular legs to propel itself from trunk to trunk. Unlike any other living lemur, the indri has only a rudimentary tail. Different populations show wide variations in color, with some northern populations consisting of mostly or entirely black individuals. The name 'indri' most likely comes from the Malagasy name endrina; an oft-repeated but incorrect story claims it comes from indry, meaning 'there' or 'there it is'. Another Malagasy name is babakoto, most commonly translated as 'ancestor' or 'father'.

Reader's Guide

The indri is significant as one of the largest living lemurs and a key species in Madagascar's eastern forests. It is revered by the Malagasy people, protected by fady (taboos), and features in origin myths where a man and his son transformed into the first indri. The indri practices long-term monogamy, lives in small family groups, and communicates with loud, distinctive songs that can last from 45 seconds to more than 3 minutes. These songs are used to solidify contacts between groups and may communicate territorial defense, environmental conditions, and warnings. The main threats faced by the indri are habitat destruction and fragmentation due to slash-and-burn agriculture, fuelwood gathering, and logging, as well as hunting despite taboos. Its conservation status is critically endangered, making its protection a priority for biodiversity conservation in Madagascar.

Did You Know?

• The indri has only a rudimentary tail, unlike any other living lemur.
• The name 'indri' most likely comes from the Malagasy name endrina, not from the word indry meaning 'there'.
• Indri groups sing almost every day, up to seven times daily, with peak singing hours between 7 and 11 am.
• The indri is revered by the Malagasy people and protected by fady (taboos), with legends telling of a man and his son transforming into the first indri.

Giant of the Canopy: Form and Color

The indri ranks among the two largest lemurs still alive, sharing that distinction with the diademed sifaka. A typical individual measures roughly 64 to 72 centimeters in head-body length and weighs between six and nine and a half kilograms, though exceptional records approach fifteen kilograms. With legs fully extended, total reach can approach one hundred and twenty centimeters. Its locomotion is strikingly specialized. As a vertical clinger and leaper, the indri holds its torso upright whether traveling between trunks or resting in a branch. Long, muscular legs propel it from tree to tree, and its large greenish eyes and black face are framed by round, fuzzy ears. Perhaps most distinctive of all, the indri possesses only a vestigial tail—a trait found in no other living lemur. Coat coloration is predominantly silky black, broken by white patches along the limbs, neck, crown, and lower back. Yet populations vary enormously; some northern groups are almost entirely black. In 2005, Colin Groves proposed two subspecies to capture this gradient, but later genetic work favors a clinal model, and subsequent editions of Lemurs of Madagascar dropped the split.

A Bond for Life: Monogamy and Matriarchy

The indri practices a form of monogamy that is essentially lifelong. A pair mates for the duration of their partnership, and only the death of one partner prompts the survivor to seek a new companion. The basic social unit is small: a bonded male and female together with their maturing young. In heavily fragmented forests, however, groups can swell to include several generations, constrained by the inability to split into smaller units. Within these groups, the female holds clear dominance. She routinely displaces the male to lower branches and less productive feeding spots, and she is typically the individual who leads the group as it travels through the canopy. Daily movement ranges from three hundred to seven hundred meters, with the greatest distances covered during midsummer when fruit becomes scarce. Sleeping occurs ten to thirty meters above the forest floor, usually in solitary or paired arrangements. A charming behavioral note: young females, and occasionally adult females, engage in silent wrestling bouts lasting anywhere from a few seconds to fifteen minutes. Groups also share designated defecation sites within their territory, using them together.

Songs of the Canopy: Vocal Communication

Few animals in the rainforest produce sounds as dramatic as the indri's song. These vocalizations can stretch from forty-five seconds to over three minutes, and their structure shifts not only between groups but even within a single group over time. Most performances follow a recognizable three-phase architecture. The opening is a roaring sequence lasting several seconds, in which every group member except the very youngest takes part. The song proper then belongs to the adult pair. They launch into a long-note phase, individual notes reaching up to five seconds in duration. This gives way to a descending phrase sequence: wails that begin at a high pitch and gradually fall lower. Two or more indri often synchronize the timing of their descending notes, producing what sounds like a duet. Groups typically sing in sequence, answering one another across the forest. These exchanges appear to serve multiple functions simultaneously—reinforcing social bonds between neighboring groups, asserting territorial boundaries, broadcasting environmental conditions, signaling the reproductive status of members, and issuing warnings. The indri may also break into song following sudden disturbances such as a crack of thunder.

Revered and Endangered: Culture and Conservation

The indri is native exclusively to Madagascar, where it occupies a place of deep cultural significance among the Malagasy people. It features prominently in local myths and legends, with numerous origin stories explaining how the animal came to be. The Malagasy name babakoto—often translated as "ancestor" or "father"—likely derives from baba (father) and koto (little boy, or the diminutive of the common name Rakoto), a father-son dynamic echoed in many of those origin tales. The scientific name indri probably traces to the Malagasy word endrina, though a persistent but incorrect legend credits French naturalist Pierre Sonnerat with mishearing a local pointing at the animal and taking the word indry, meaning "there it is," as the species' name. Despite this cultural reverence, the indri faces severe pressure. Slash-and-burn agriculture, fuelwood collection, and logging have destroyed and fragmented its forest habitat. Hunting persists even where taboos against it exist. The International Union for Conservation of Nature classifies the species as critically endangered.