The description "indri" simply means "there it is", a term that was mistakenly believed to be the native name for this particular lemur! The indri is easily identified by its stumpy tail. It has a longer muzzle than the sifakas and a naked black face.
The indri is the largest of all the living prosimians, and, like the lemurs, it is found only in Madagascar. Indris are arboreal and move about by jumping between tree trunks and stems. Sometimes indris come down to the ground, where they stand upright, moving in series of ungainly leaps. These lemurs spend most of their time off the ground. Their feet are well-adapted for their environment as, apart from the big toe, their toes are fused together.
They are mostly active by day and spend a lot of time feeding on leaves and fruit. Indris live in small family groups of up to five members, and occupy large home ranges. The central part of a home range is defended from others by the adult male, which uses scent markings and calls to signal the limits of the territory. Wiping their muzzles on branches may also leave a scent behind to warn off those who might encroach into their territory.
Indris have thick silky fur, which may be useful for living in cold mountain forests, as high as 1800 m (6000 ft) above sea level. There is considerable variation in fur colour, which ranges from black through browns and greys to white.
Sometimes several members of a group will make loud tuneful songs that can be heard up to 2 km (1.25 miles) away. These songs are thought to signal occupancy of a territory to other groups, but also to unite groups and broadcast willingness to mate.
Mating takes place in January or February, and the females give birth to 1 young after a gestation period of between 4 1/2 and 5 1/2 months.
Distribution: Restricted to Madagascar, off the southeastern coast of Africa. Found in the northeast of the island, from sea level up to 1800 m (5900 ft).
Habitat: Tropical rainforest.
Weight: 7 - 10 kg (15.4 - 22 lb); males are slightly larger.
Length: 66 - 96 cm (26 - 38 in).
Maturity: 7 - 9 years for both sexes.
Gestation Period: 120 - 150 days.
Breeding: 1; weaning occurs at around 6 months; females typically breed every 2 - 3 years.
Diet: Mainly fruit, but also leaves and other vegetation, including flowers.
Lifespan: Probably up to 40 years.
These are set quite low on the head and have a distinctive tufted appearance.
This can vary quite markedly. Black areas may be replaced by brown or even grey.
This is very much larger than the thumb, helping the lemur to grasp the branch.
This is tiny and vestigial, only measuring about 6 cm (2.4 in) long.
A young indri lemur clings on to its mother’s belly for five months, before shifting position to her back for a further two months.
This is likely to reinforce the pair bond between these lemurs.