RANDRIANASOLO'S SPORTIVE LEMUR
Geographic Distribution and Habitat
Like all lemurs, Randrianasolo’s sportive lemur (Lepilemur randrianasoloi), also known as the Bemaraha sportive lemur, is found only in the isolated island country of Madagascar, situated in the Indian Ocean about 250 mi (400 km) off the coast of East Africa across the Mozambique Channel. These prosimians live in the central-western region of the country. Their geographic distribution extends from the Manambolo River in the north, within Tsingy de Bemaraha National Park and the adjacent Bemaraha Strict Nature Reserve (the area from where the species takes its alias); to Tsiribihina River in the south, where these primates occupy two larger forest fragments in the north and east of Andramasay Forest. Extent of occurrence is estimated as less than 849 sq mi (2,200 sq km) at elevations ranging from 154 to 456 ft (47 to 139 m) above sea level, with an average of 299 ft (91 m). Further research of this little-studied primate species is necessary to determine precise distribution, population numbers, and density.
Dry, deciduous forest provides Randrianasolo’s sportive lemur with its habitat.
But the ecology of the region is a bastion of natural wonder, thanks to its dramatic karst (limestone) landscape. Spectacular limestone towers jut upward and limestone ridges line the forest. Fissures and sinkholes further define the topography. Deep between Tsingy de Bemaraha National Park and Bemaraha Strict Nature Reserve, small lakes and mangrove forests can be found in the gorges—other lemur species can be found here, too.
Within Tsingy de Bemaraha Strict Nature Reserve (a world heritage site), so-called “tsingy” peaks and an awe-inspiring limestone “forest” encompasses 376,600 ac (152,405 ha) with rocky pinnacles that stretch upward 2,600 ft (793 m).
In the Malagasy language, “tsingy” means “where one cannot walk barefoot”—a reference to the tall, thin, needle-like rock formations found throughout the country.
Size, Weight, and Lifespan
Sportive lemurs (Lepilemur) are medium-sized primates of the family Lepilemuridae, composed of 26 species within the genus.
The Randrianasolo’s sportive lemur is slightly smaller than its close cousins and neighbors, the Antafia sportive lemur (also known as the AEECL or red-shouldered sportive lemur, Lepilemur aeeclis), and the red-tailed sportive lemur (Lepilemur ruficaudatus). Males and females are roughly the same size. Head-to-body length averages a mere 11.3 in (28.7 cm), with hind limbs that are much longer than the forelimbs. A nonprehensile tail adds another 11 in (27.6 cm). Adults weigh from 1.5 lb to 1.9 lb (0.66–0.88 kg), with an average weight of 1.7 lb (0.775 kg).
Lifespan in the wild has not been studied in detail, nor definitively reported. However, some researchers assert that these primates probably live more than 12 years.
Male and female lemurs strongly resemble one another; other than their genitalia, the sexes cannot be distinguished. (This condition is known as sexual monomorphism, the opposite of sexual dimorphism).
A light gray fur coat cloaks the body of this diminutive, other-worldly-looking primate of the primitive suborder Strepsirrhine. Rust-colored fur decorates the shoulders, back, hindlimbs, and topside of forearms. The tail is a lighter shade of rust.
Characteristic of all prosimians, Randrianasolo’s sportive lemur is fitted with enormous ears, relative to its tiny body, that jut out from its head like ears of a bat. (In comparison to its neighboring sportive lemur cousins, the Randrianasolo’s sportive lemur has a more narrow and slightly longer head.) Large, round, copper-to-green colored beguiling eyes seem capable of casting a spell with their gaze. Mother Nature has taken a dark pencil and outlined the globe of each eye to complete their supernatural effect. A dark-colored moist muzzle (similar to the wet snout of a dog) gives contrast to a light gray, pointy furred face. Because its nose is connected to the upper lip, which is connected to the gumline, facial expressions are limited. But with those spell-casting orbs, a wide range of facial expressions hardly seems necessary.
These sportive lemurs lack upper incisors, but, characteristic of prosimians, they are fitted with a so-called “second tongue.” This sublingual muscular cartilage, located beneath the primary tongue, assists in grooming their dense fur coats.
Two elongated toes (the second toe of each foot, adjacent to the big toe), known as “toilet claws,” are used for grooming.
Randrianasolo’s sportive lemurs are herbivores who eat mostly leaves, making the species folivorous. Pollen, seeds, seed pods, fruits (in particular, nectarines), flowers, and tree bark round out their menu.
According to new research, the main reason sportive lemurs eat so many leaves is that Madagascar’s fruits do not supply adequate nutrition. While leaf cellulose (the main structural component in leaves) provides a good source of amino acids (the so-called “building blocks” of proteins), an enormous amount of leaves is necessary to meet dietary protein requirements. That’s a lot of leaf cellulose to digest! Fortunately, lemurs (like other folivorous primates) are equipped with a specialized digestive system. Bacteria living at the base of the large intestine break down the cellulose, toward the end of digestive tract, efficiently converting it to protein. A low basal metabolic rate (one of the lowest recorded for any primate) is a complementary evolutionary adaptation that may aid in the digestion of potentially toxic chemicals found in some leaves; it also allows the lemurs to conserve energy—an important survival mechanism when food is scarce. Another magic trick (or rather, evolutionary adaptation or biological wonder), is the ability of this strepsirrhine primate to produce its own Vitamin C!
Occasionally, sportive lemurs engage in cecotrophy, the practice of eating their feces. Researchers posit that the reason they do this is to take in extra nutrients, found in the broken-down leaf cellulose of the lemurs’ soft poop pellets. (Bunny rabbits also engage in cecotrophy.)
Behavior and Lifestyle
These little animals are creatures of the night, meaning they are nocturnal (and not vampires, though some might find them spooky looking). They lack color vision, but a light-reflecting eye membrane, known as the tapetum lucidum, helps these primates to see in the darkness. As light enters the eye, it bounces off this membrane (located directly behind the retina) to create what is colloquially referred to as “eye shine”—thereby illuminating the shadows. (Cats share this evolutionary adaptation.)
Randrianasolo’s lemurs spend most of their time in the trees, which makes them arboreal. Their long and powerful rear legs propel them as they travel quadrupedally (on all four limbs), running and leaping, vertically, from tree to tree. Large pads on the hands and feet help with traction. Their long, nonprehensile tail does not appear to assist much with balance.
During daylight hours—“bedtime” for these sportive lemurs—they retreat to a tree hole and sleep rolled up in a ball.
Madagascar’s top carnivore and main predator of lemurs is the fossa, a mammal related to the mongoose but more cat-like in appearance with retractable claws and sharp teeth.
Sorting out the name:
Named for the pioneering Malagasy primatologist Georges Randrianasolo, this prosimian’s scientific name was initially L. randriansoli, but was later determined to be an incorrect spelling. Thus, in 2009, the scientific Latin name was corrected to L. randrianasoloi.
The word “lemur” (/ˈliːmər/), from the Latin word lemures, means “ghost” or “spirit.”
These sportive lemurs prefer their own company and are mostly solitary. Individuals typically forage on their own, though mothers take their infant children along on these expeditions. To ascertain which foods are safe to eat and to identify other individuals, these lemurs rely on their keen sense of smell.
An individual’s home range is only about 2.5 ac (1 ha). While a male’s territory might be larger than that of a female, or overlap a female’s territory, females are dominant to males. Therefore, when food resources within a territory are scarce, a female gets first dibs. Researchers believe this feeding priority is crucial for reproductive success. Males are known to be highly territorial with other males, however, and may fight with one another when there is a lack of food.
Sympatric species include their cousins, the red-shouldered sportive lemur and the red-tailed sportive lemur. Additionally, 131 of the 186 resident terrestrial bird species listed for Madagascar live in Tsingy de Bemaraha Strict Nature Reserve. They have adapted perfectly to their environment, deftly navigating the razor-sharp limestone landscape.
Sportive lemurs are known for their loud territorial and defense cries. When faced with a predator threat, they emit harsh, noisy grunts, growls, and crow-like calls. They may chase off or engage in combat with an intruder.
But it’s not just their own vocalizations that these solitary primates pay attention to: they are able to recognize alarm calls of more-social lemur species—and also recognize the specific warning calls of certain birds! Their ability to understand the language of these other animals helps them to evade predators.
While other species of lemurs are known to engage in social grooming sessions (important in establishing bonds with one another), the solitary Randrianasolo’s sportive lemur is left to groom herself (the exception is new mothers, who likely groom their infants). But Mother Nature has equipped this prosimian with the necessary tools (its toilet claw and second tongue), so there’s no excuse for not looking good.
Although male sportive lemurs are fitted with scent glands in their scrotum, only rarely have they been observed engaging in marking behavior (leaving olfactory cues).
Reproductive data specific to Randrianasolo’s sportive lemur is scant, so information is gleaned from other lemurs who share the genus Lepilemur.
While some lemur species practice monogamy (a mating system in which a male and female mate exclusively with each other), sportive lemurs practice polygyny (a mating system in which a male animal has more than one female mate).
Researchers have coined the term “lemur syndrome” in an attempt to explain the varied mating systems of Madagascar’s lemur species. Besides female dominance in the species and male submissiveness, other variables include additional behavioral, morphological, and demographic traits. The syndrome is posited to be an evolutionary response to the island’s capricious environment. A phenomenon known as “scramble competition polygyny” occurs when males must compete for access to breeding females; locating the females (who are often widely dispersed) is a key aspect of this “sporting” (or sportive) competition.
Further research is necessary to more fully comprehend the mating systems of Madagascar’s lemurs.
Sportive lemurs reach sexual maturity—when males are capable of siring and females are capable of conceiving—at about 18 months of age. Mating occurs between May and August (the dry season). A female gets a male’s attention with the distinct swelling of her genitalia, indicating that she is in estrus. After a gestation period of about 135 days, a single infant is born between September and November. Between December and April, the region experiences its heaviest rainfall, encouraging new plant growth and providing plentiful food sources for nursing mothers. Mothers nurse their babies for their first four months of life. During this period, she may carry her infant in her mouth as she travels. At about 1 year old, sportive lemurs are considered to be independent. But young sportive lemurs are at risk of falling from trees and are more vulnerable to predators, more so than full-grown adults who can deftly escape.
Their intense appetite for leaves makes these primates excellent tree pruners. They may also contribute to the regeneration of their forested environment. Seeds of the select fruits they eat are dispersed, via their feces, throughout their habitat, encouraging new plant growth.
Randrianasolo’s sportive lemur is classified as Endangered by the International Union for Conservation of Nature (IUCN, May 2018), appearing on the IUCN Red List of Threatened Species.
Habitat loss resulting from human activity is the primary threat to the species’ survival, along with degradation of habitat from unsustainable agricultural practices. But the looming specter is the earth’s climate crisis. Human-induced climatic shifts in temperature are expected to cause an estimated 87 percent reduction in the species’ range, from the year 2000 to 2080. If this grim prediction is realized, the species can become extinct, like the more than 17 lemur species who have already disappeared from our earth.
Randrianasolo’s sportive 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.
Because the species’ geographic distribution is limited to Tsingy de Bemaraha National Park and the adjacent Bemaraha Strict Nature Reserve (in theory, both protected areas), as well as forest fragments within Andramasay Forest, conservationists stress the need to vigilantly protect and preserve these areas from further habitat loss.
Founded in 2015, The Lemur Conservation Network (LCM) is a project of the IUCN Species Survival Commission Primate Specialist Group. In 2021, the network became an independent not-for-profit organization, registered in the USA. By providing a network that includes over 60 conservation organizations, LCM raises awareness about lemurs, identified as “Madagascar’s flagship mammal species” by Conservation International, to protect them from extinction.
Founded in 2013, Impact Madagascar recognizes that to successfully circumvent habitat loss, the needs of local people must be addressed, along with the needs of wildlife. This environmental nongovernmental organization (NGO) works with local communities to develop programs that improve daily life while promoting conservation through sustainable environmental protection. Its focus is on community health and development, biodiversity conservation, and environmental outreach.
Written by Kathleen Downey, October 2021