Common Brown Lemur, Eulemur fulvus
COMMON BROWN LEMUR
Eulemur fulvus
Geographic Distribution and Habitat
Like all lemurs, brown lemurs are endemic to Madagascar, an island located approximately 250 miles (400 km) off the coast of East Africa, and one of the richest biodiversity hotspots in the world.
Common brown lemurs can be found in several areas on the island. In the west, populations inhabit tropical and sub-tropical dry forests from the Betsiboka River in the north to the Mahavavy du Nord River. They are also found in forest fragments on the central plateau. The eastern moist lowland and montane forests populations of common brown lemurs are found from the Ambatovaky Special Reserve down to the Onive and Mangoro rivers. There is also a small population just south of the Mangoro River in the Vohitrambo and Vohibe forests.
Mayotte, a volcanic island in the Indian Ocean between Madagascar and the coast of Mozambique, is also home to groups of common brown lemurs. They were likely introduced from Madagascar by people during early settlement of the island.
Size, Weight, and Lifespan
Common brown lemur males and females weigh between 4 and 6 pounds (1.8-2.7 kg). Their bodies average 16 to 20 inches (41-51 cm) in length. Their non-prehensile tail is as long as their body and helps them maintain balance as they walk quadrupedally on branches or leap from tree to tree.
Their lifespan in the wild is approximately 25 years. Under rare, highly managed captive conditions—such as in well-resourced, professionally run institutions—some individuals may live longer than 30 years. The oldest brown lemur in captivity reached the ripe age of 35.5 years.
Appearance
These slender and elegant lemurs have a dense, soft, grayish-brown pelage, hence their name. The northern populations of common brown lemurs are easily recognizable by the light patches of fur above their eyes. The shiny fur covering their head and snout is black.
Their snout is long and thin with a wet nose. Their teeth are sharp with incisors that cut like scissors. The front bottom teeth are close together and form what is referred to as a toothcomb that lemurs use to clear their fur of parasites.
The delicate features of their faces are highlighted by two round, bright orange eyes that face forward, which tells us these lemurs have binocular vision and therefore have good depth perception. A reflector membrane, the tapetum lucidum, located behind the retina, makes their eyes glow at night and enhances their night vision.
Common brown lemur forelimbs are shorter than their legs. Their thighs are muscular and their legs long, a useful feature that allows them to take long leaps and appear as if they were flying between branches.
Their hands and feet are thin with five long digits. Opposable thumbs and toes afford a secure grip on branches. Their palms and the bottoms of their feet are bare and ridged, like ours. The second digit on their feet, the toilet claw, has a long, pointy nail that they use for grooming. Their long, bushy tail is the same color as the rest of their body. It helps lemurs keep their balance as they walk or leap through the canopy.
Diet
The diet of common brown lemurs varies during the year depending on food availability, but it typically consists of fruit (78%) and leaves (13%); however, their consumption of young and mature leaves increases during the dry season. Common brown lemurs are said to feed on more than a hundred different plant species, although they consume only a subset of that consistently. They innately select leaves that are high in protein and minerals that fruit doesn’t provide. They supplement their intake with bark, tree exudates, bird eggs, and animal prey (including insects, centipedes, millipedes, nestlings, chameleons, and frogs). Those in Mayotte have been observed ingesting mud from crab burrows, thereby supplementing their nutritional needs with minerals found in soil.
With fast gut passage, their anatomy is perfectly adapted to their diet. An analysis of the chemical components of plants in Madagascar and Mayotte showed that common brown lemurs are able to ingest leaves and immature fruit with high levels of tannins and alkaloids that plants produce to defend themselves against folivorous animals. Because brown lemurs are not bothered by these chemicals, they have access to food resources that other lemur species cannot exploit.
Common brown lemurs are also adaptable to environmental changes. In two instances, following droughts, groups of common brown lemurs in Ankarafantsika National Park responded to periods of food scarcity by traveling farther than usual and feeding from two plant species they normally would not—the grewia tree and Landophia myrtifolia shrub.
In recent years, with an ever-shrinking habitat, common brown lemurs occasionally resort to foraging in agricultural areas—especially crops of guava fruit—which puts them in conflict with farmers who may trap or kill them as pests.
Behavior and Lifestyle
Common brown lemurs are gregarious, rather shy, and timid. They differ from other lemur species in two ways. They live in groups that have no distinct hierarchy between males and females, unlike in other lemur species, where females are dominant over males. Males and females are co-dominant. To defend and advertise their territory, common brown lemur males maintain spatial distance from other groups by vocalizing.
Common brown lemurs generally don’t travel far each day, and their home range averages 1.75 to 2.5 acres (0.75–1 ha), but in dry or disturbed habitats, they travel farther to find the specific food items they need and prefer.
When studying conflicts, scientists noticed that female common brown lemurs intervened when their own kin were involved, and males intervened when juveniles were involved. Their intervention was non-aggressive yet effective, and it ended the conflict every time.
When they are threatened by a predator, common brown lemurs get stressed out and behave differently than they normally do when things are calm. Scientists observed that they scratch themselves more, for instance, after an attack by a predator like a hawk, or if they enter into conflict with other brown lemurs. They also noticed that higher-ranking common brown lemurs scratched less and had lower cortisol levels than lower-ranking individuals, suggesting that stress is more intense for the latter. Scratching decreases when lemurs reconcile or don’t feel threatened.
Legends about lemurs are many in Malagasy folklore. Lemurs are generally considered sacred with strong links to the spirits of human ancestors; as such, they are both revered and feared, which is why it was historically taboo and forbidden to eat them. Another legend says that humans who transgressed divine teachings were transformed into lemurs as punishment from God.
On the island of Mayotte, brown lemurs are called “biby natanana,” which means animals belonging to the house or the village. Apart from one archaeological site in Dembeni, where finds seem to indicate that lemurs may have been eaten by humans when they first arrived on the island, there aren’t many clues about their history. They are described as unafraid of humans in the writings of an explorer named John Studdy Leigh in 1838, and the only documented hunting practice appears in the journal of Francois Pollen, a Dutch naturalist, who wrote about French colonists hunting the poor animals with dogs in 1868.
For centuries, common brown lemurs were also involved in a rite of passage. Young boys would build a temporary shed on their parents’ land and disappear into the forest until they captured a baby brown lemur. Upon their successful return to the village, the boys were considered adults and were allowed to keep the lemur as a pet. Now that brown lemurs are protected, this tradition has been abandoned.
Groups vary in size based on location. These are usually composed of equal numbers of males and females and include adults, juveniles, and infants. On average, group sizes consist of 5-13 individuals. In Mayotte, the limited natural habitat reduces the average group size to 6 individuals.
Where the forest is lush and most populated, there can be as many as 40 to 60 lemurs per 0.4 mile (1 square km). Populations are smaller in other areas, like the lowland rainforests of the Ankeniheny-Zahema Corridor (CAZ) in eastern Madagascar, where density does not exceed 10 individuals per 0.4 square mile (1 square km). This protected area—one of the largest rainforests remaining in Madagascar—has been affected by illegal mining, especially since the discovery of sapphires there in 2016. Since then, deforestation has accelerated, especially along the rivers, where waters are now spoiled by sediment, soil, and other contaminants.
Common brown lemurs are early risers, and groups generally have had their first meal by 10 each morning. After eating, they rest for a couple of hours and may be seen lying on branches with their stomach exposed to the warm rays of the sun. They resume foraging around noon, then alternate between foraging and resting until evening, continuing as long as light allows. They are cathemeral (active during the day or night throughout the year). On nights when the moon is bright, they are more active than on darker nights as moonlight allows them to detect predators and food more easily. They are typically less active when the weather is warm. When they are ready to sleep, they bundle up on tree branches in clumps of 2 to 5 individuals.
In many areas, Common brown lemurs share territory with ring-tailed lemurs (Lemur catta). The two lemur species do not fight over resources because they occupy different layers of the forest. Brown lemurs spend the majority of their time in the canopy or lower levels of the trees, and only 2% on the ground, whereas ring-tailed lemurs are more terrestrial (land-dwelling).
In northwestern Madagascar, common brown lemurs share their territory with mongoose lemurs (Eulemur mongoz). They also do not have resource conflicts because the two species are active at different times.
Lemurs communicate through vocalizations, touch, and scent. As wet-nosed primates (strepsirrhines), they rely on scent more heavily than vision to interpret and communicate with the world around them. Equipped with scent glands on their chests and wrists, they rub surfaces to mark their territory. The scent marks left behind are chock-full of useful information for other lemurs. It tells them whether the scent belongs to a young or older female or male, if the female is in estrus (ready to mate), if the individual is healthy, and where that individual has been or how long ago the marking was left.
When resting, common brown lemurs groom one another to establish and maintain social bonds. They have a toothcomb, a dental structure of fine teeth on the lower jaw, to facilitate grooming. While grooming, they grab and isolate tufts of hair with their hands, then lower their mouth to comb through, clean, and remove parasites with their teeth.
They use various vocalizations throughout the day, each with a specific purpose. To maintain social cohesion with other members of the group, for instance, they emit a nasal sound that primatologists refer to as “ohn.” When they want to let the group know that a predator is near, they produce a loud “crou” alarm call. But if they want to dissuade outsiders from getting too close, they may face members of an opposing group and harangue them with tail wagging and a high-pitched sound called “cree.” Eventually, the other group retreats, and no harm is done.
Common brown lemurs reach sexual maturity at about two years of age (509 days for females, 633 days for males). They mate between May and June, but the mating season only lasts three weeks. Females come into estrus at different times and are only receptive for 24 hours. To attract males, females increase their scent-marking activity. When they are interested, males approach them from behind and stand over them, holding the females by the hips. Jealous individuals may interfere.
After a gestation (pregnancy) of approximately 120 days, females give birth to a single infant, generally in October. Twins are rare. At birth, the baby weighs approximately 2.5 ounces (73 grams). Females can give birth again a little over a year after (about 548 days), although climate and food availability influence females’ reproductive cycles.
For the first three weeks, babies hang onto their mothers’ bellies. When they are a little older and stronger, they ride on their mothers’ backs. Infant mortality is high during the first few months of life. Babies need a strong grip to not fall to their demise. They are also at high risk of dying from parasitic infestation or being preyed upon. Until their babies are weaned (around 7 months of age), mothers devote more time to foraging because they need more calories to sustain themselves.
Since they consume fruit, common brown lemurs play an important role as seed dispersers. A study on seed dispersal patterns in the northwestern forests of Madagascar found that they disperse seeds of different plant species during the rainy season. The dispersal of large seeds is important to the restoration of deteriorated forests. Small-seeded species rarely bear fruit during the dry season, but a few large-seeded species do. One of them (Vitex beraviensis) is a vital food source for common brown lemurs.
By eating insects, they limit the insect population; as prey, they provide a source of protein for other animals.
As leaf eaters, they contribute to the pruning of the trees they dwell in, thereby keeping trees healthy by promoting air flow and sun exposure.
The International Union for Conservation of Nature lists the common brown lemur as Vulnerable (IUCN, 2018), appearing on the IUCN Red List of Threatened Species.
Scientists consider that the range of the species is sufficiently large and the population is stable. This may change in the future when more data is available.
Forest destruction, due primarily to slash-and-burn practices, charcoal production, and illegal logging, is the principal threat. All these human activities negatively impact the forest by fragmenting or destroying it altogether. The island of Mayotte lost close to 30% of its forested areas in the second half of the 20th century. Natural forests are rare. They have been replaced by forest gardens, which developed in the second half of the twentieth century when the last rice and sugar cane plantations were closed, and land was returned to the farm workers. These forest gardens are typically less than 2.5 acres (1 ha) in size, where fruit such as mangoes and bananas is grown. To illustrate, between 1973 and 2014, Madagascar lost 37% of its forest cover and, according to prediction models, brown lemurs will have lost nearly half of their home range due to climate change alone by 2080.
Although common brown lemurs seem to adapt well to fragmented forests, their population has decreased by half since the 1970s. Since their home range is small to begin with, rapid habitat changes put a lot of stress on these primates, and they find themselves more often than not in close proximity to humans. Because their habitat is shrinking, common brown lemurs have developed new behaviors, unseen until about fifteen years ago. They often raid crops and eat fruit that isn’t yet ripe; hungry common brown lemurs have even been reported getting into houses and acting aggressively toward people, including children.
Although historically, the Malagasy people viewed lemurs as almost human, in a more Westernized society, ancestral thinking is losing ground. Climate change is also putting more pressure on farmers, as their crops are increasingly vulnerable to frequent storms, droughts, and water shortages. So farmers are actively fighting against an animal they now consider a pest, and they can kill it when caught crop-raiding.
This happened in the past, when colonial authorities ruled. According to oral testimonies of villagers in Mayotte, in the late nineteenth century and until 1946, Westerners on the island viewed common brown lemurs as pests, just like rats, bats, and wild pigs. The authorities at the time even paid villagers to kill them, based on the number of tails they brought back from the hunt.
Studies show that common brown lemurs can be infected with viruses that also affect humans, including herpes viruses, pox viruses, chikungunya virus, Zika virus, and flaviviruses. Common brown lemurs are also one of the lemur species most susceptible to contracting tuberculosis (TB) and transmitting it to other lemurs. Females are more vulnerable than males to the disease. These animals can also share the same bacteria and parasites as humans, such as Salmonella and Clostridium. These examples illustrate how important it is for all living organisms to maintain healthy forests.
Natural predators include hawks, boa constrictors, and the fossa.
The common brown lemur is listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
Many governmental and international agencies, as well as non-profit organizations, are actively working to protect lemurs. The Hannover Institute of Zoology is one example. They monitor lemur populations, collect data, provide education, and focus on the species’ adaptation to climate change. They work closely with the two main universities in Madagascar, local authorities, and the Malagasy population on conservation efforts. The Wildlife Conservation Society monitors lemur populations and conducts field research. They also work with the Malagasy Government on ways to enforce regulations. Antananarivo University’s GERP group (Groupe d’Etude et de Recherche sur le Primates) was created in 1994. Their primary goals are research and conservation plans, which include animal relocation to areas with healthier forests. They work closely with educators and local communities.
Madagasikara Voakajy, yet another group, implemented a monitoring program using camera traps. They provide education to primary school students and encourage community associations to manage natural resources and create sustainable jobs for women and young people. Others, like Planet Madagascar or Eden Reforestation, focus on planting trees and preventing wildfires.
Ecotourism provides some income to local people. Protected areas receive about half of the fees collected from visitors who come to admire the beauty and biodiversity of this island. Many businesses in the world participate in carbon offset programs. They buy credits to offset their excess carbon emissions and to finance reforestation. Unfortunately, environmentalists agree that these programs are insufficient. Only a small portion of the funds collected reaches the poorest populations who rely on the forest for their livelihoods.
Monocultures of banana and cassava have gradually replaced old-style farming on the island of Mayotte, causing soil degradation, deforestation and the depletion of water resources. Because lemurs often have little choice but to forage in agricultural areas, one of the proposed solutions to help conserve common brown lemur populations on the island is to translocate them to protected areas, like the Mbouzi Natural Reserve. Although this is an interesting idea, it doesn’t address the issues monocultures create and somewhat contradicts the biodiversity model, which we should all aim for to reestablish a balanced ecosystem as nature once knew it.
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- Scratching around stress: Hierarchy and reconciliation make the difference in wild brown lemurs (Eulemur fulvus) – Elisabetta Palagi, Ivan Norscia
Written by Sylvie Abrams, June 2026