COMMON BROWN LEMUR
Geographic Distribution and Habitat
Like all lemurs, brown lemurs are endemic to Madagascar—a country approximately 250 miles (400 km) off the coast of East Africa, and the fourth largest island in the world (it is almost twice the size of Arizona). Because the island has been detached from Africa for 180 million years and is isolated from any other continent, most of the animals and plants found in Madagascar are unique to the island.
Sometimes referred to as the Great Red Island because of the color of its soil, the country has a narrow coastal plain, a high plateau, and mountains. Each region has a different climate—for example, the east is tropical, hot, and wet; the central plateau inland is cooler; and the south is dry.
Brown lemurs are found in the northern part of the island. On the west side, they live in the tropical and sub-tropical deciduous forests that stretch north of the Betsiboka River and below the Mahavavy du Nord River. In the east, they live in the evergreen rainforests that spread from Ambatovaky Special Reserve in the north down to the Onive and Mangoro rivers. A small population also lives in the grassland and rainforests of Ambohitantely Special Reserve in the central plateau.
Groups of brown lemurs are also present on Mayotte, a volcanic island in the Indian Ocean between Madagascar and the coast of Mozambique. There is no record of how the lemurs arrived on Mayotte some 1,500 years ago, but humans likely had something to do with it!
Size, Weight, and Lifespan
These arboreal prosimians weigh 4 to 6 lbs. (1.8–2.7 kg). Males and females are about the same size. Their non-prehensile tail is as long as their body, which averages 16 to 20 inches (41–51 cm). The tail helps the lemurs maintain balance as they walk quadrupedally on branches or leap from tree to tree.
They can live up to 30 years in the wild; longer in captivity.
These slender and elegant lemurs have a dense and soft caramel color pelage, hence their name. Males and females have the same coloring—a characteristic unique to this Eulemur species. Their long, bushy tail is the same color as the rest of their body. The shiny fur covering their head and snout is black. 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.
Their 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.
What Does It Mean?
(Of animals) tending to form a group with others of the same species.
A bacterium, virus, or other microorganism that can cause disease.
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Brown lemurs are folivorous and frugivorous. Their diet, which varies during the year depending on food availability, consists of fruit, mature leaves, young leaves, and flowers. Although nearly 70% of their diet is fruit, in the dry season, they mainly eat foliage. They are said to feed from a hundred different plant species, although they consume only a subset of that consistently.
A study on the chemical components of plants in Madagascar and Mayotte showed that brown lemurs are able to ingest leaves and immature fruit with high levels of tannins and alkaloids that plants produce to defend themselves. As a result, many lemurs (and other species) avoid eating them, but because brown lemurs are not bothered by these chemicals, they have access to food resources other lemur species cannot exploit.
Brown lemurs are also adaptable to environmental changes. In two instances, following droughts, groups of 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.
Brown lemurs in Mayotte have been observed ingesting mud from crab burrows, so it is probable that these lemurs occasionally supplement their diet with minerals found in soil.
In many areas, they share territory with ring-tailed lemurs. The two lemur species do not enter into conflicts for resources because they occupy different strata 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. Ring-tailed lemurs are more terrestrial.
In the northwest of Madagascar, brown lemurs share territory with mongoose lemurs. They too do not have conflicts for resources because the two species are active at different hours.
In recent years, with an ever-shrinking habitat, 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
Brown lemurs are gregarious and live in groups that have no noticeable hierarchy—unlike many other lemur species’ groups in which females are dominant. Groups vary in size based on location. They are usually composed of as many males as females and include adults, juveniles, and infants. On average, groups count 3 to 12 individuals. In Mayotte, they tend to be larger. Where the forest is lush and most populated, there can be as many as 40 to 60 brown lemurs per square kilometer (0.4 square mile). Much less in other areas, like the lowland rainforests of the Ankeniheny-Zahema Corridor (CAZ) in eastern Madagascar, where density doesn’t exceed 10 individuals per square kilometer (0.4 square mile). 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 since 2016. Consequently, deforestation has accelerated, especially along the rivers, where waters are now spoiled by sediment, soil, and other contaminants.
A study on seed dispersal patterns in the northwestern forests of Madagascar found that common brown lemurs disperse seeds of different plant species during the rainy season. Some of these are small and others are large seeds. The fact that they disperse large seeds is important to the restoration of deteriorated forests, which ensures the survival of these prosimians. 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 brown lemurs.
Daily Life and Group Dynamics
Brown lemurs are cathemeral, which means they may be active during the day or night throughout the year. Nighttime activity increases when the moon is bright, which allows them to detect predators and food more easily. They are generally less active when temperatures are higher.
These lemurs are early risers and the groups have had their first meal by 10 a.m. 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 and continue as long as light allows.
They generally don’t travel far each day and their home range averages 1.75 to 2.5 acres (.75–1 ha). In dry or disturbed habitats, they have to travel farther to find the specific food items they need and prefer.
Rather timid and shy, brown lemurs are not territorial and, unlike other lemurs, males do not patrol the borders of the group’s territory. They simply maintain spatial distance with other groups by vocalizing.
When they are ready to sleep, they bundle up on tree branches in clumps of 2 to 5 individuals.
Lemurs communicate through vocalizations, touch, and scent. 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 if the scent belongs to a young or older female or male, if the female is in estrus, if the individual is healthy, and where that individual has been or how long ago the marking was left.
When resting, brown lemurs groom one another to establish and maintain social bonds. They have a toothcomb, a dental structure of fine teeth on the jaw. While grooming another lemur, 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 the an opposing group and harangue them with tail wagging and a high-pitched sound referred to as “cree.” Eventually, the other group retreats and no harm is done.
Reproduction and Family
Brown lemurs reach maturity by the time they are two years old. They mate seasonally between May and July—although the actual mating season only lasts two to three weeks—during which females come in estrus at different times and are only receptive for 24 hours. To attract males, they increase their scent marking activity.
Between September and November, and after a gestation of approximately 125 days, females give birth to a single infant. Twins are rare. They can give birth again a year later, 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 while producing milk for their offspring.
Since they consume fruit, brown lemurs play an important role as seed dispersers. By eating insects, they limit the insect population; as prey, they provide a source of protein for other animals.
Conservation Status and Threats
The International Union for Conservation of Nature lists the common brown lemur as Vulnerable (IUCN, 2018), appearing on the IUCN’s Red List of Threatened Species. Their population has been declining at an estimated rate of 30% per 24 years (three generations). They are primarily threatened by habitat loss, hunting, and the pet trade.
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. 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. Since their home range is small to begin with, rapid habitat changes put a lot of stress on these primates—not to mention the fact that some are hunted by humans for food or captured for the illegal pet trade.
The situation is similar for brown lemurs living in Mayotte. Their population has decreased by about half since the 1970s.
As their habitat shrinks, all animals in Madagascar and Mayotte find themselves in dangerous and close proximity to humans. Studies show that brown lemurs can be infected by viruses that also affect humans, such as herpes, pox, chikungunya, zika, and flavivirus. They can also share the same bacteria and parasites, such as salmonella and callistoura. This sharing of pathogens illutrates how important it is for all living organisms to maintain healthy forests.
Brown lemurs appear in Appendix I of the Convention on International Trade in Endangered Species (CITES). Many governmental agencies and international and non-profit organizations are actively working to protect them. The Hannover Institute of Zoology is one example. They monitor lemur populations, collect data, provide education, and focus on species adaptation in the face of 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 is another. They monitor lemur populations and conduct field research. They also work with the Malagasy Government on ways to enforce regulations. Antananarivo University’s GERD group 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. Madagasikar 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 wild fires.
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 compensate for their excess carbon emissions and finance reforestation. Unfortunately, environmentalists agree these programs are insufficient. Only a small part of the funds collected reach the poorest populations who exploit the forest for their livelihood.
- britannica.com/place/MadagascarDuke Lemur Center website
- Animal Diversity website
- Lemur Conservation Network website
- Abiotic factors affecting the cathemeral activity of Eulemur fulvus in the dry deciduous first of north-western Madagascar – Razanparany P.T., Sato H. (2020)
- Vector-Borne Zoonotique Diseases, Vol 17, No 5 – Absence of Evidence of Rift Valley Fever Infection in Eulemur fulvus (Brown lemur) in Mayotte During an Interepidemic Period – Raphaêlle Métras, Laure Dommergues, Katia Ortiz, Marion Pannequin, Christian Schuler, Patrick Roux, John W. Edmunds, Matt J. Keeling, Catherine Cêtre-Sossah, Eric Cardinale (2016)
- Biomedical Evaluation of Brown Lemur (Eulemur fulvus spp) Population From Mbouzi Islet, Mayotte Island – Benoït Quintard, Brice Lefaux, Alexis Lécu, Flenk Niphuis, Patrick Roux, Katia Ortiz (2019)
- Primate Ecology and Social Structure – Volume 1: Lorises, Lemurs and Tarsiers – Robert W. Sussman
- Habitat shifting by the common brown lemur (Eulemur fulvus fulvus): a response to food scarcity – Hiroki Sato
- Feeding behavior of lactating brown lemur females (Eulemur fulvus) in Mayotte: influence of infant age and plant phenology – Laurent Tarnaud
- REDD-monitor.org – Ankeniheny-Zahamena Corridor, Madagascar: “The economic viabilities of carbon offsetting are ridiculous” – Chris Lang
- telegraph.co.uk – Carbon offsetting may be a gold mine in the West – but in Madagascar, sapphires are the real prize – Hayley Dixon
- Richesse en métabolites secondaires des forêts de Mayotte et de Madagascar et incidence sur la consommation de feuillage chez deux espèces de lémurs (Eulemur spp) – Bruno Simmen, Laurent Tarnaud, Françoise Bayart, Annet Hladik, Anne-Laure Thiberge, Stéphanie Jaspart, Marc Jeanson, André Marez. (Revue d’Ecologie – 2005)
- Seasonal fruiting and seed dispersal by the brown lemur in a tropical dry forest, north-western Madagascar (2013) – Hiroki Sato
- Common Brown Lemur – The Lemur Conservation Foundation www.lemurreserve.org
Written by Sylvie Abrams, January 2021