Sanford’s Brown Lemur, Eulemur sanfordi
SANFORD'S BROWN LEMUR
Eulemur sanfordi
Geographic Distribution and Habitat
The Sanford’s brown lemur (Eulemur sanfordi), also known as Sanford’s lemur, is one of many terrestrial lemur species endemic to the island country of Madagascar, located about 250 miles (402 kilometers) east of Africa’s southern tip. Endemism, the state of a species only being found in a single defined geographic location, is reflected in wild populations of the Sanford’s brown lemur because this is the only area in the world where this species can be found.
Throughout their geographic range, although small populations exist in the Daraina region, most populations are concentrated in three major forest areas: Ankarana, Analamerana, and Montagne d’Ambre. Populations of this species mostly occur in Madagascar’s northernmost tip, spreading from the regions of Antsiranana to Ampanakana. The Manambato River is the southernmost limit of this species’ range.
In Madagascar, there are two defined seasons: a hot, rainy season from November to April and a cooler, dry season from May to October. During the rainy season, temperatures may reach between 60 to 80 degrees Fahrenheit (15 to 26.6 degrees Celsius). During the dry season, temperatures may be between 55 to 75 degrees Fahrenheit (13 to 24 degrees Celsius). Sanford’s brown lemurs live in various forms of subtropical forests, as distinguished by the forests’ climates: tropical dry or tropical moist.
Sanford’s brown lemurs also prefer living in high-density evergreen forests, in elevations of up to 4,593 feet (1,400 meters). Highlands tend to be cooler and less humid than coastal regions, and considering temperatures vary across regions, rainfall occurrences may be higher in the east and lower in the southwest.
Occurring over 120 million years ago, Madagascar broke away from Africa during one of Earth’s earliest major rifting events. During this event, scientists believe nearly 100 lemur species rafted to Madagascar on clumps of vegetation. As an island nation, wild populations of the Sanford’s brown lemur had no means of escaping until the arrival of humans.
Primates can be broken into two suborders: anthropoids and prosimians. Anthropoids, or simians, consist of humans, monkeys, and apes, while lemurs are considered prosimians. Based on today’s taxonomic research, since about 10 million years separate the first anthropoids from the first prosimians, lemurs are considered to be the oldest living primates on earth.
The Sanford’s brown lemur is a strepsirrhine primate, belonging to the Lemuridae family. Until this species was promoted to full-species status in 2001, this lemur was previously considered a subspecies of the common brown lemur (Eulemur fulvus). It is named after Leonard Cutler Sanford, an American surgeon and ornithologist who acted as a trustee of the American Museum of Natural History.
Size, Weight, and Lifespan
The average weight of a Sanford’s brown lemur is between 4.0 to 4.2 pounds (1.8 to 1.9 kilograms). The overall length of the Sanford’s brown lemur varies between 35 to 38 inches (88 to 95 centimeters): the head-to-body length is between 15 to 16 inches (38 to 40 centimeters) and their tail length is between 20 to 22 inches (50 to 55 centimeters).
Wild populations of the Sanford’s brown lemur typically have a lifespan of around 9 years.
Appearance
Unlike other primate species, lemurs have snouts instead of curved nostrils. These snouts are long, hairless, and wet to the touch. These characteristics helped them to become master sniffers, which is especially important for a species that relies heavily on their sense of smell to carry out daily activities.
In appearance, males and females slightly vary from one another. Males have grayish-brown coats of hair on their backs that extend to their hands, feet, and base of tail. Their faces and noses are black, and a crown of white fur tufts out from the sides. Unlike females, males also have a light brown cap of fur sitting just on top of their heads, almost like a naturally occurring hat. Compared to their male counterparts, female Sanford’s brown lemurs are much darker. Their dark coat coloring extends throughout their body, and rather than having dark and distinct facial features, a female’s face may appear to be more gray.
Both males and females have bright orange eyes that closely resemble the color of carrots or Halloween pumpkins. Nearly all lemur species lack the ability to see color on red wavelengths, but it is unclear whether or not the Sanford’s brown lemur is an exception to this rule. There is not enough evidence to suggest whether or not having orange eyes affects this species’ ability to see.
Diet
The Sanford’s brown lemur is an omnivorous species. Although research is scarce, scientists determined that lemurs often prefer consuming plant products from trees greater than 33 feet (10 meters) tall. This diet typically consists of fruit, buds, flowers, and young and mature leaves. Considering their geographic range, Sanford’s brown lemurs most likely enjoy eating plant products from plant species such as the Za Baobab (Adansonia za), the Madagascar periwinkle (Catharanthus roseus), the Madagascar Ocotillo (Alluaudia procera), and saw palmetto (Serenoa repens). On average, they can eat between 9 to 17 plant species per month!
Although these creatures primarily consume plant products, they have also been identified eating may sap, bark, soil, and small insects. Depending on the seasonal availability of some plants, they may consume invertebrate species such as centipedes, millipedes, and spiders.
Feeding activities for the Sanford’s brown lemur peak during the rainy season, between the months of December to February.
Behavior and Lifestyle
Unlike most primate species, Sanford’s brown lemurs exhibit cathemeral activity behaviors. Cathemerality, translated as “through the day” in Greek, is a term applied to an individual who displays activity patterns during the day, and at night. Using their strength and grip to move between trees, these animals are typically identified by the sounds of crashing leaves and branches. Sanford’s brown lemurs eat, sleep, feed, and give birth amongst the trees, so it is unsurprising that they may be heard before they are seen. Unfortunately, as forests decline due to habitat loss and deforestation, it has become increasingly common to find these animals stepping beyond their forest boundaries, often in search of food sources. If traveling on the ground, you will see these creatures moving on all fours.
As a direct result of their active lifestyle and naturally occurring curiosity, it is important for Sanford’s brown lemurs to constantly be aware of their surroundings, especially when hiding from predators. The predators most likely to threaten these animals are fossas (Cryptoprocta ferox), Madagascar harrier-hawks (Polyboroides radiatus), Madagascar ground-boas (Acrantophis madagascariensis), and Malagasy civets (Fossa fossana).
Did you know lemurs have two tongues?
In addition to their primary tongue, lemurs have another tongue-like structure called the sublingua. The sublingua, or second tongue, is made of a strong form of connective tissue, or cartilage. Because of the sublingua’s strength and sturdiness, it has become the perfect tool for grooming practices, especially when used on other troop members. When cleaning other lemurs, the sublingua helps get rid of unwanted objects embedded within fur patches, such as dead skin or small insects. Small insects even have the potential to become a delicious grooming snack. Talk about having each other’s back!
The average troop size of a Sanford’s brown lemur is between 4 to 15 individuals and roughly consists of an equal number of males and females. During the rainy season, when food availability is greatest, Sanford’s brown lemurs have been identified interacting with other lemur species, specifically with crowned lemurs. Combining multiple troops, there is significant evidence to suggest that these two species enjoy creating large leaping groups, typically made of up to 30 individuals. Together, these lemurs explore and traverse their home ranges, often covering up to 34.6 acres (14 hectares) of distance!
Each troop of Sanford’s brown lemurs is led by a dominant female or matriarch. Because of her ranking, these females often get the first choices of food and the first choice of a mate. Their position also allows them to decide troop movements and defense strategies when defending their home range.
In order to assert her dominance, a high-ranking female may bully, or intimidate, lower-ranking troop members in order to get them to fall in line. This behavior is displayed when she chases them, pinches their tails, pulls their fur, slaps, steals, or bites them. That being said, it is not uncommon for lower-ranking females to challenge their matriarch, specifically through fighting. During the fights, where females may use their sharp teeth and claws in order to dominate one another, each female hopes to gain respect and advance socially. Once a winner is determined, the loser must submit and retreat from her opponent. Once this occurs, the challenge is over.
When defending home ranges, female Sanford’s brown lemurs chase off intruders with territory calls, rather than using forms of physical aggression. When warding off predators, these lemurs produce a series of grunting noises, dissimilar to other lemur species who vocalize through wailing and chirping.
Because lemurs exist in a hierarchical society, scent marking and grooming play an important role in establishing order and maintaining social bonds. Allogrooming, as well as removing hard-to-reach dirt and parasites, is a form of social bonding, while scent marking is particularly used to signal territorial boundaries. Female scent glands can be found near their genital regions, while male scent glands can be found on their wrists.
Sanford’s brown lemurs are a polygynous species; males may mate with multiple females, but females only mate with one male. Mating typically occurs in May, during Madagascar’s dry season, when females are sexually receptive for single 24-hour periods. Males may aggressively fight one another during the mating season to gain female attention. If the aggression becomes too excessive, some male individuals may be kicked out of the group by the dominant female for their behavior.
After a gestation period of between 120 to 125 days, females give birth to a single infant between September to October, when plant species abundantly flourish. Once birthed, newborns cling to their mother’s chest for roughly two weeks. Once they gain upper body strength, infants slowly transition from their mother’s chest, onto her back. As they reach 1 month old, infants become more independent, and after 4 months old, infants become fully weaned.
Both male and female Sanford’s brown lemurs reach maturity at around 2 years old.
Sanford’s brown lemurs often consume plant products such as fruits, buds, flowers, and leaves. Since less than 1/4 of all lemur species can claim to be frugivores, these creatures are especially unique! Frugivores play critical roles in forest growth and development. After consuming and digesting food products, frugivores disperse seeds through their feces, therefore replenishing their ecosystem. The efficient gut passage of Sanford’s brown lemurs provides greater seed germination, evidently increasing the conservation of plant diversity within their natural habitat. This behavior is especially important in Madagascar’s Amber Forest Reserve, where most of the population call home. Since these lemurs consume a large variety of plant species each month, they are considered their ecosystem’s best germinators!
The International Union for Conservation of Nature lists the Sanford’s brown lemur as endangered (IUCN, 2018), appearing on the IUCN Red List of Threatened Species.
The primary threat to the survival of Sanford’s brown lemur is habitat destruction, specifically because of sapphire mining and slash-and-burn practices. Evidently, as the quality of their habitat decreases, so does the occurrence of this species. According to the IUCN Red List of Threatened Species, the geographic habitat of this species is severely fragmented and population sizes are expected to reduce by almost 50% in the next three generations.
In addition to habitat destruction, poaching and hunting practices are predominant threats to this species. Unfortunately, within the Antsiranana region of Madagascar, Sanford’s brown lemurs are hunted and commonly kept as pets. Widespread poaching often occurs in the country’s Montagne d’Ambre National Park and the Analamerana Special Preserve.
The Sanford’s 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.
Wild populations of this species are known to occur in two national parks within Madagascar’s borders: in the forests of the Analamerana Special Reserve and the forests of Daraina. That being said, hunting and poaching practices have been reported elsewhere throughout the country.
To protect this species for current and future generations, land and water management, site and area management, species management, and harvest management are critical. It is also very important for researchers to collect more data while participating in species observation, as well as observing population trends.
- Chen KS, Li JQ, Rasoarahona J, Folega F, Manjaribe C. Diet and Effects of Sanford’s Brown Lemur (Eulemur sanfordi, Archbold 1932) Gut-passage on the Germination of Plant Species in Amber forest, Madagascar. Zool Stud. 2016 May 31;55:e21. doi: 10.6620/ZS.2016.55-21. PMID: 31966166; PMCID: PMC6409440.
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Written by Brooklynne Mitchell-Arno, August 2024