INDRI
Indri
Geographic Distribution and Habitat
This rare and unique primate is—like all lemurs—endemic to the island of Madagascar. It can be found in the lowland rainforests of the island’s northeast region, notably in the Anjanaharibe-Sud wildlife preserve. Indris are best suited for montane and coastal rainforests, since they do not travel on the ground, and rely on trees to get from place to place. The trees of these forests also provide essentially all of the food this species eats. Elevation-wise, they do best at low to medium elevations, not exceeding 5,905 ft (1,800 m). They are not adept at coping with disturbances in their habitat; their range is so limited because they rely heavily on protected forests, since so much of their habitat is jeopardized by logging and agricultural pressures.
This rare and unique primate is—like all lemurs—endemic to the island of Madagascar. It can be found in the lowland rainforests of the island’s northeast region, notably in the Anjanaharibe-Sud wildlife preserve. Indris are best suited for montane and coastal rainforests, since they do not travel on the ground, and rely on trees to get from place to place. The trees of these forests also provide essentially all of the food this species eats. Elevation-wise, they do best at low to medium elevations, not exceeding 5,905 ft (1,800 m). They are not adept at coping with disturbances in their habitat; their range is so limited because they rely heavily on protected forests, since so much of their habitat is jeopardized by logging and agricultural pressures.
Indri geographic range map. Credit: Alex Dunkel (Maky) and IUCN
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What Does It Mean?Simulacrum: A representation of something. An unsatisfactory imitation or substitute. Slash and burn agriculture: A method of unsustainable farming, where farmers clear land by cutting and burning flora in order to create an empty field—a “swidden”—for cultivation. Such practices are detrimental to local ecosystems. |
Size, Weight, and Lifespan
The indri is one of the largest lemurs in the world; it weighs between 13 and 21 lb (6-9.5 kg) and typically ranges from 25 to 28 in (64-72 cm) in length. While the tails of most lemurs are approximately equal in length to their bodies, the indri has a very short tail—typically only about 2 in (5 cm) long.
They live between 15 and 18 years in the wild, and do not fare well in captivity. No indri has ever survived more than a year in captivity. Research suggests that the diet of the indri is nuanced (they eat certain foods at certain times of day) and cannot be replicated in captivity. Also, when taken from the wild, these lemurs, for reasons which remain unclear, do not reproduce. Captive breeding is not always straightforward; potential impediments to success vary from overlooked social cues, idiosyncrasies which can’t be replicated in captivity, or just too large a rift between the wild setting and the simulacrum created in captivity.
Appearance
These lemurs have round, hairless faces with, large, fuzzy ears—like a teddy bear’s. Their circular eyes are bright and honey colored with small black pupils. The indri’s fur is skunk-like in coloration, predominantly black with white along the arms, legs, belly, and neck, and on top of the head. It has been suggested that indri coloration is regional—their fur gets darker in the northernmost reaches of its range. The indri’s hind legs are very long, and come in handy when jumping through the trees; the indri can jump up to 30 ft (10 m) between branches. They have nimble fingers, which aid them in foraging for food, eating, and gripping trees.
The indri is one of the largest lemurs in the world; it weighs between 13 and 21 lb (6-9.5 kg) and typically ranges from 25 to 28 in (64-72 cm) in length. While the tails of most lemurs are approximately equal in length to their bodies, the indri has a very short tail—typically only about 2 in (5 cm) long.
They live between 15 and 18 years in the wild, and do not fare well in captivity. No indri has ever survived more than a year in captivity. Research suggests that the diet of the indri is nuanced (they eat certain foods at certain times of day) and cannot be replicated in captivity. Also, when taken from the wild, these lemurs, for reasons which remain unclear, do not reproduce. Captive breeding is not always straightforward; potential impediments to success vary from overlooked social cues, idiosyncrasies which can’t be replicated in captivity, or just too large a rift between the wild setting and the simulacrum created in captivity.
Appearance
These lemurs have round, hairless faces with, large, fuzzy ears—like a teddy bear’s. Their circular eyes are bright and honey colored with small black pupils. The indri’s fur is skunk-like in coloration, predominantly black with white along the arms, legs, belly, and neck, and on top of the head. It has been suggested that indri coloration is regional—their fur gets darker in the northernmost reaches of its range. The indri’s hind legs are very long, and come in handy when jumping through the trees; the indri can jump up to 30 ft (10 m) between branches. They have nimble fingers, which aid them in foraging for food, eating, and gripping trees.
Diet
The indri is an herbivore, more specifically a folivore—an animal who survives mainly on a diet of leaves. The indri relies heavily on laurels. It has a preference for immature leaves, because they are more tender, but will also forage for flowers, seeds, fruit, or bark. They eat similarly to humans, using their fingers to pick up twigs and biting off the leaves. When moving about, the dominant female leads the troop. Troops travel up to 0.4 mi (700 m) daily, though on a typical day they only travel half that distance.
The indri is an herbivore, more specifically a folivore—an animal who survives mainly on a diet of leaves. The indri relies heavily on laurels. It has a preference for immature leaves, because they are more tender, but will also forage for flowers, seeds, fruit, or bark. They eat similarly to humans, using their fingers to pick up twigs and biting off the leaves. When moving about, the dominant female leads the troop. Troops travel up to 0.4 mi (700 m) daily, though on a typical day they only travel half that distance.
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Behavior and Lifestyle
These lemurs are diurnal, spending most of their time in the trees. Indris sleep in the trees, and very few of their food items aren’t tree-based. They are very social creatures, and are fond of playing; the females are particularly fond of wrestling. The entire troop will urinate on the boundaries of their territory to deter trespassers. Daily Life and Group Dynamics The day of an indri kicks off with collective urination and defecation by the group. Next, they forage and eat for pretty much the entire day. It is estimated that up to 60% of indri behavior is related to food. These lemurs, after a long day of feeding, finish up their day by grooming. Then, still in the trees, they either pair off and go to sleep or sleep by themselves. The tree serves as a representation of the hierarchy within lemur society: since females are in charge, males are often relegated to lower branches of the trees, where food is of lower quality. When females reach sexual maturity, they are given priority as far as food goes; they have access to the highest branches, with the best leaves. |
Fun FactsThe indri is also called by the name “babakoto.” In Malagasy, “baba” means “father”; “koto” means “little boy”; “babakoto” translates to “father of a little boy.” The indri often plays a paternal role in Malagasy lore, and some say that this name is derived from the indri’s song, which is comparable to a father calling out for his son. |
Communication
One of the most widely recognized things about this species is its long vocalizations, which can be heard up to 1.25 mi (2 km) away. The indri’s “song,” which can last multiple minutes, sounds like an amalgam of a whale song, an airhorn, and the air being let out of a balloon. The call is sung in a group, in what sounds like call and response, like a chorus; they even synchronize the rhythms of their song with each other. The cumulative volume of a group of indris is meant to deter other lemurs from entering their territory. Male indris often sing the higher notes, while females sing lower. Indris also bark when they feel threatened.
One of the most widely recognized things about this species is its long vocalizations, which can be heard up to 1.25 mi (2 km) away. The indri’s “song,” which can last multiple minutes, sounds like an amalgam of a whale song, an airhorn, and the air being let out of a balloon. The call is sung in a group, in what sounds like call and response, like a chorus; they even synchronize the rhythms of their song with each other. The cumulative volume of a group of indris is meant to deter other lemurs from entering their territory. Male indris often sing the higher notes, while females sing lower. Indris also bark when they feel threatened.
Reproduction and Family
Indris practice monogamy—they will not look for another partner until their partner is dead. Females reproduce once every two to three years. Like traditional human families, groups of indri consist of the mated adult pair and their offspring, though groups may grow to include multiple generations as habitat grows scarce. Sexual maturity is reached as early as age seven, or as late as age nine, with females giving birth every two to three years after that, one infant at a time. Their gestation period is 120 to 150 days. Reproduction is seasonal, limited to the months of May and June. Infants are independent of their mothers after eight months, but will stay with them for two years.
Indris practice monogamy—they will not look for another partner until their partner is dead. Females reproduce once every two to three years. Like traditional human families, groups of indri consist of the mated adult pair and their offspring, though groups may grow to include multiple generations as habitat grows scarce. Sexual maturity is reached as early as age seven, or as late as age nine, with females giving birth every two to three years after that, one infant at a time. Their gestation period is 120 to 150 days. Reproduction is seasonal, limited to the months of May and June. Infants are independent of their mothers after eight months, but will stay with them for two years.
Ecological Role
Madagascar is unique in its biodiversity. Approximately 80% of species on the island are endemic to it—they can’t be found anywhere else. Thus, every species in Madagascar is an integral part of the ecosystem’s puzzle. Even by merely serving as prey for other species, this species is critical. Also, like many primates, they disperse seeds.
Madagascar is unique in its biodiversity. Approximately 80% of species on the island are endemic to it—they can’t be found anywhere else. Thus, every species in Madagascar is an integral part of the ecosystem’s puzzle. Even by merely serving as prey for other species, this species is critical. Also, like many primates, they disperse seeds.
Conservation Status and Threats
The indri’s situation is dire. This species is Critically Endangered according to the International Union for Conservation of Nature (IUCN, 2014). Estimations of the population vary, ranging from one to ten thousand. The principal threats faced by the indri are pressures on their habitat, such as logging and slash and burn agriculture; there has also been a recent uptick in human hunting of this species. Malagasy culture puts forth a fady, or a cultural law, against hunting indri, but these fady are becoming less and less respected.
Conservation Efforts
One of the main ways this species can be saved from extinction is through protecting its habitat. Fortunately, numerous national parks and nature reserves provide safe havens for indris—even if logging still occurs in protected areas. Captive breeding is not an option, but simply taking the initiative to educate people about the value of this species and the existential threat it faces could go a long way.
The indri’s situation is dire. This species is Critically Endangered according to the International Union for Conservation of Nature (IUCN, 2014). Estimations of the population vary, ranging from one to ten thousand. The principal threats faced by the indri are pressures on their habitat, such as logging and slash and burn agriculture; there has also been a recent uptick in human hunting of this species. Malagasy culture puts forth a fady, or a cultural law, against hunting indri, but these fady are becoming less and less respected.
Conservation Efforts
One of the main ways this species can be saved from extinction is through protecting its habitat. Fortunately, numerous national parks and nature reserves provide safe havens for indris—even if logging still occurs in protected areas. Captive breeding is not an option, but simply taking the initiative to educate people about the value of this species and the existential threat it faces could go a long way.
Video of Indris calling to eachother courtesy of ARKive.org
References:
- http://www.iucnredlist.org/details/10826/0
- https://en.wikipedia.org/wiki/Indri#cite_note-Giacoma-16
- http://www.bioone.org/doi/abs/10.1644/1545-1410%282002%29694%3C0001%3AII%3E2.0.CO%3B2
- https://link.springer.com/article/10.1007%2Fs10764-010-9412-8
- https://www.lemurworld.com/indri-lemur/
- https://www.rainforesttrust.org/project/saving-the-critically-endangered-indri-lemur/
- http://www.wildmadagascar.org/wildlife/lemurs-indri.html
- https://a-z-animals.com/animals/indri/
- http://pin.primate.wisc.edu/factsheets/entry/indri
- https://www.stlzoo.org/conservation/wildcare-institute/lemursinmadagascar
- http://thescienceexplorer.com/nature/listen-haunting-song-these-lemurs-madagascar
- https://animaldiversity.org/accounts/Indri_indri/
- https://www.bbc.com/news/science-environment-33286942
- http://www.slate.com/articles/news_and_politics/explainer/2005/03/why_is_captive_breeding_so_hard.html
Written by James Freitas, June 2018
