Red Brown Lemur, Eulemur rufus
RED BROWN LEMUR
Eulemur rufus
Geographic Distribution and Habitat
The red brown lemur resides in northern Madagascar and has been seen from the Betsiboka River to the Tsiribihina River. Because of the rapid habitat loss that Madagascar—and all the lemurs living there—is facing, they occur in patch-work distribution. They occur in the still-existing forests from the Betsiboka to Mahavavy Rivers, from Ambato-Boeny to Ankirihitra, and from Maevatanana District to the Ikay forest.
They reside in dry, deciduous forests, and primary and secondary rainforests. They have also been known to live in and use mangrove forests, which are plants and trees that have adapted to loose, wet soil that sometimes becomes a swamp-like environment. They are found between 902 and 5,479 feet above sea level (275 to 1,670 m). They do not often inhabit edge areas of the forest, which is the forest boundary between two habitats, such as forest and farmland.
From 1973 to 2014, Madagascar lost 37% of its forest. The cause of deforestation is largely slash-and-burn agriculture, a process in which a farmer burns vegetation to make way for a field, and enriches its soil from the added ash. While effective temporarily, the field will be unproductive in just a few short years.
The red brown lemur is known by several names due to its taxonomic journey throughout the years. It was once considered a subspecies of the common brown lemur, Eulemur fulvus, and evidence of this can be found in many journals and articles prior to the late 1990s. The Eulemur rufifrons (the red-fronted lemur) was considered a junior synonym or taxonomic name that was published in literature after Eulemur rufus (the red brown lemur) – although it has been determined that rufifrons is distinct from rufus. Commonly, the red brown lemur is also known as Audebert’s brown lemur.
Size, Weight, and Lifespan
The red brown lemur varies slightly in weight, from around 4.8 to 5 pounds (2.18 to 2.30 kg). In length, they measure 1.2 feet (3.78 cm), and their tails add another 1.6 feet (50 cm). They are not a sexually dimorphic species, meaning their size does not change depending on their sex. Interestingly, though, there is considerable variation in testicle size among the males. Some males have testicle sizes 2 to 7 times larger than other males in the group. It’s unknown if this correlates to reproductivity or dominance within the group, but it is thought to aid in sperm competition. In the wild, they live to be 20 to 25 years old, though in captivity they have been known to live up to 30.8 years.
Appearance
Though not sexually dimorphic in size, the red brown lemur is sexually dichromatic. This means that males and females have different coloration. Males are gray and brown on their backs and shoulders, and their undersides are cream-gray. Their furry faces are marked with white fur from their cheeks up to their brows, and from the bridge to the tip of their nose they have black fur. Their forehead to the crown of their head is a burnt orange color. Females have similar coloration, however they often have more orange on their backs and shoulders. They also lack the orange crown that the males sport.
Diet
Red brown lemurs are an exceptionally frugivorous species, meaning their diet consists heavily of fruit. In fact, fruit makes up over 50% of their daily caloric intake. The rest of their diet is made up of leaves, flowers, insects, and arthropods. These lemurs spend about 2.8 hours per day eating, though these eating sessions are broken up into about 22 sessions per day. Unfortunately, their feeding time negatively correlates with available fruit in the area — yet another consequence of the deforestation in Madagascar. They are known to migrate when fruit is low in their area, which is a seasonal occurrence. From October to March fruit is scarce, and their fallback food during this time is insects such as walking sticks, flies, and ants.
They are known to partake in geophagy on occasion, which is the purposeful consumption of dirt. Additionally, they have been known to exhibit coprophagy or the consumption of feces. Geophagy often adds to their diet as a supplement, and coprophagy is seen in many species for the purpose of ingesting nutrients that were not digested the first time around.
Behavior and Lifestyle
Red brown lemurs are cathemeral, which means they do not sleep exclusively at night or during the day, but rather their sleep is dispersed throughout the 24-hour cycle. They are more active during the day, though, their nighttime activity is correlated with the phases of the moon and how much moonlight they have. Males and females both engage in agonistic behavior between other groups. In captivity, they have been observed as having reconciliatory behavior after conflict. This behavior includes tongue-licking and allogrooming (grooming another individual).
Males often disperse from their natal groups at around 3 to 4.5 years of age, and this helps maintain genetic diversity among the populations. New males are readily incorporated into the group, and more often than not they stay in their new group for the remainder of their lives. As they age, males become more peripheral in the group. Females have also been observed dispersing from their natal group, but it is unknown how common this behavior is.
Madagascar is known to have varying seasonal temperatures. The red brown lemur responds to cold by huddling together as a group, or inactivity. It’s common for males to participate in male-only social thermoregulation, that is huddling together to stay warm.
A group of lemurs is called a conspiracy!
The red brown lemur lives in groups of 5 to 18 individuals. They live in multi-male/multi-female groups with a male-biased sex ratio, that is, having more males than females. Unlike most lemur species, the red brown lemur has been described as male-dominant. However, females do have priority of food and lead the group to food sources. Males are responsible for the protection of the group, and the dominant male has sexual choice priority.
Groups have been known to permanently fission into smaller groups and disperse altogether, which is most likely due to food scarcity and availability.
Red brown lemurs have a repertoire of physical and vocal communication cues. Grunts and contact calls, which include an “ohn” sound act as a means to keep the group close while foraging, and to maintain group cohesion. Alarm calls sound like a high-pitched “cree” yet the alarm call often changes attributes depending on the threat.
Lemurs rely on their noses more than many other primates, therefore they use a suite of olfactory cues to communicate with one another. Scent marking, in which the lemur rubs specialized scent glands on their forearms on branches, rocks, or other surfaces, helps denote territory. High-ranking males in the group tend to have more scent-marking behavior. Males tend to engage with the scent marking of females much more than females engage with the scent marks of males.
Red brown lemurs live in multi-male/multi-female societies. They are polygynous, meaning that males and females both have multiple partners. The polygynous method of reproduction is thought to reduce infanticide (killing of infants, usually by a male hoping to displace another male’s progeny), and is further aided by the females’ discreet estrus, meaning it is not physically obvious that a female is ovulating. Within the group, females will often interact more with the dominant male, though they may copulate with every male member of their group during their fertile cycle.
Females reach sexual maturity between the ages of 2 and 4 years old, though older females have a better likelihood of having a successful pregnancy than younger females. This may be due to the link between maternal body weight and successful births in this species. Upon reaching sexual maturity, females will partake in copulatory behavior with mature males, who mature a little later at 3 to 4.5 years old.
Females are fertile for 1 to 3 days, but they copulate for several days before and after this as well. The red brown lemurs have a breeding season from May to June, and most females in the group will experience estrus during this time. They gestate (the length of pregnancy) for approximately 4 months, and give birth to one offspring. The female will nurse for 6 months following the birth, and the mother and infant both stay somewhat isolated from the rest of the group. Males do not participate in any alloparenting, which is the term for care given to an infant or juvenile not by the mother.
As a highly frugivorous species, the red brown lemur is a vital seed disperser in Madagascar. They are predated by fossa in their region and are parasitized by mites that do not seem to bother them.
The International Union for Conservation of Nature lists the red brown lemur as Vulnerable (IUCN, 2018), appearing on the IUCN Red List of Threatened Species, and their population is decreasing.
More than 30% of the red brown lemurs’ population is expected to be lost in the next 3 generations. The primary threats contributing to this species loss are decline in habitat, unsustainable hunting, and habitat fragmentation. Madagascar relies heavily on subsistence farming and slash-and-burn agriculture. It also relies heavily on tourism. These two modes of livelihood are often at odds with each other.
The red brown lemur is also captured and targeted for the illegal pet trade.
The red 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.
The red brown lemur is found in several protected areas in Madagascar. Three national parks, Baie de Baly, Tsingy de Bemaraha, and Tsingy de Namoroka. They are found in four reserves, Tsingy de Bemaraha Strict Nature Reserve, Bemarivo, Kasijy, and Maningoza, and the Tsiombokibo Classified Forest. Other groups not in these areas are sometimes “adopted” by community members and are protected by conservation groups.
Red brown lemurs are not often found in zoos, with only 75 individuals living in zoos globally. However, many more are in captivity due to illegal pet ownership.
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Written by Robyn Scott, July 2024