All you need to know about the critically endangered Indri lemur – including why it makes such haunting calls
In the dense rainforests of Madagascar, a haunting call reverberates through the canopy, a sound both eerie and enchanting. This is the call of the indri lemur, one of the largest living lemurs and a critically endangered species.
However, beyond its captivating presence lies a story of survival and vulnerability. As deforestation and hunting continue to threaten its habitat, the indri’s future hangs in the balance.
What are indri lemurs?
Indri lemurs are large-bodied lemur, weighing 6–10kg with a head-and-body length of 60–90cm, but despite their size they are not always easy to spot among the foliage. They make up for this by being highly vocal, producing ear-splitting wails known as ‘long calls’, which carry over 2km and sometimes even up to 4km.
What do indri lemurs sound like and why do they call?
Indri lemurs call to defend territories. The performance, most often taking place in the morning, is a way of saying to neighbouring indri families: “We are here, this is our patch,” and when one group starts singing you’ll hear more distant groups take up the challenge. This ensures that indri groups don’t have to waste precious energy patrolling their territories and fighting with neighbouring clans. Their calling also acts to bring the family together should they become separated while foraging.
What do indri lemurs look like?
Known for its striking black-and-white appearance, indri have a stocky build with powerful hind limbs and stumpy tails. Their face is small – relative to body size – and it has a distinctive pointed muzzle and large expressive eyes.
Where do indri live?
Indri live in Madagascar’s eastern rainforests. As folivores, or leaf-eaters, indris spend nearly all their lives in the trees although they are occasionally seen coming down to the ground. They’re certainly happiest when moving around in the trees and frequently feed 40m above the forest floor.
How long do Indri live for?
Indri are long-lived too, capable of reaching 40 years of age, and their extended lifespan is combined with a strong maternal investment in single offspring.
How often do female indri give birth?
Adult females give birth to an infant every two or three years, usually in May or June, and the youngsters stay with their parents until they reach sexual maturity at around eight years of age.
Do indri lemurs mate for life?
Indris are one of the few animals that mate for life and live with their partner and their young. Like many lemur societies, the indri society is matriarchal: in indri families, it’s the females who wear the trousers. Not only are they larger than the males (linked to their dominance and the need to carry large infants on their backs), they also lead their families and claim the best positions while feeding.
The young stay close to their mothers, learning how and where to find food. Jody Weir, a researcher from Canada’s University of Victoria, has observed them feeding on their mother’s excrement. This sounds strange to us but is eminently sensible: it helps infants to develop the gut flora that will enable them to process their leaf-based diet.
How far can indri leap?
It’s their phenomenal locomotor ability that makes them particularly special, as these are the most specialist of all the so-called ‘leaping lemurs’ – the group that includes the indris, sifakas and avahis, or woolly lemurs. Long, powerful hind limbs, with stumpy tails so short they don’t get in the way, give indris the perfect leaping body shape, making jumps of up to 10m appear effortless.
Indris move through all levels of the forest, but travel most in the mid-layer, above the thick undergrowth and below the uppermost branches, which ensures they have plenty of clear space between the vertical trunks from which they jump. Despite their relatively large size, they prefer small supports that they can grasp with their pincer-like hands and feet.
How active are indi lemurs?
Despite their impressive leaping ability, and hence turn of speed, indris are generally quite lethargic lemurs. The ‘Black Heads’, for instance, defended a surprisingly small territory. In the warm, southern hemisphere summer they can travel up to a kilometre a day, yet during the cold winter months they might move no more than 300m. True, ‘cold’ and ‘rainforest’ are not words you often associate with one another but, winter days at Andasibe-Mantadia National Park are grey, rainy and temperatures never rise above 14°C, and at night are only just above freezing.
For indris, periods of relative inactivity make sense. Leaves, especially old leaves in winter, are very low in energy. So indris spend only 40 per cent of their waking hours foraging, devoting much of the remainder to digesting the large quantities of vegetation they’ve just consumed. Indris have thus been able to carve out their own unique niche, enabling them to coexist with the host of other lemur species in this fabulous rainforest. You could call it a case of ‘sit on what you eat; eat what you sit on’.
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Why are indri often called ‘Babakoto’?
The people call the indris ‘Babakoto’, which means the ‘Father of Koto’. The traditional story goes that Koto, a Malagasy man who lived near the forest, was out looking for wild honey, a delicacy in Madagascar. He found a bee nest high up in a tree and climbed up to get some honey. When he was extracting it, the bees started to sting him and he fell from the tree. Then, an indri leapt from the trees to catch Koto and carry him safely to the ground. After that, the Malagasy respected and did not disturb the indris.”
Herrera goes on to explain that indris may well be responsible for the term ‘lemur’. Lemur is derived from the Latin word for ‘ghosts’ and probably refers to the eerie cries of indris heard by the first Western explorers to Madagascar.