Weasel Sportive Lemur, Lepilemur mustelinus
WEASEL SPORTIVE LEMUR
Geographic Distribution and Habitat
Weasel sportive lemurs, also called greater sportive lemurs or greater weasel lemurs, are endemic to the primary and secondary rainforests of Eastern Madagascar, a large island off the coast of East Africa. The species is found in protected areas, such as the Mantadia and Zahamena national parks, the Analamazoatra and Mangerivola special reserves, as well as the Betampona and Zahema nature reserves. Populations spread between the Onive and Mangoro rivers to the Maningory River.
Climate in the region is tropical and humid with a rainy and a dry season. Annual precipitations average 39–59 inches (1–1.5 m) and, even during the dry season (August to December), showers are a regular occurrence. Temperatures average 48–82 F (9–28 C) most months of the year. March, April, and December are the hottest months; August and September are the coolest.
Size, Weight, and Lifespan
Weasel sportive lemurs are small and there is no significant difference in size between males and females. Most individuals weigh between 2 and 2.5 pounds (0.9–1.2 kg). Females are slightly heavier than males. Their body is 8–10 inches (22–25 cm) long with females being a little longer than males.
Their estimated longevity is 12 years.
The body of the weasel sportive lemur is covered in brownish-reddish woolly fur on the back, and cream color fur on the belly. Their face looks almost triangular—rounded on the top and pointy at the snout. Their large eyes are perfectly adapted to nocturnal life, containing a membrane that reflects back visible light through the retina and onto the photoreceptors, thereby allowing them to see clearly in the dark. This membrane also makes their eyes shine in the night. Their ears are round sit on the sides of their head. Unlike other mammals, they do not have any upper incisors.
Their hind legs are strong and much longer than their arms. Their feet and hands have five digits. Their hands have opposable thumbs. Their tail, which is about the same length as their body and fairly large, helps them maintain balance in the trees.
Weasel sportive lemurs forage alone. They primarily eat leaves and supplement their diet with fruit and flowers, bending branches to their mouth and eating leaves directly from the stem. Interestingly, compared to other folivorous lemurs, they prefer to select leaves that are high in fiber and alkaloids, chemical components that have nitrogen in them, but low in tannins and proteins. They get their proteins from plants with high levels of hemicellulose (which is lower in sugar than cellulose). Why they select leaves of lesser nutritional quality than other species is not clear. One hypothesis is that they feed at the lower levels of the forest rather than in the upper canopy, where the chemical components of foliage are richer than in that in the lower levels. However, this hypothesis is not certain because in forested areas where the weasel sportive lemurs feed at the same height as eastern woolly lemurs, they still select leaves lower in protein than their neighbors.
Foliage is more difficult to digest than fruit, so weasel sportive lemurs have teeth and an elongated caecum, a pouch that is considered to be the beginning of the large intestine, that are perfectly suited to their diet. The bacteria in their caecum break down cellulose.
There are reports of other sportive lemurs re-ingesting their feces (which contain the broken down cellulose), so it is possible this is the case for weasel sportive lemurs as well.
Behavior and Lifestyle
These solitary lemurs are nocturnal and arboreal, which makes population counts in the wild difficult. Although in some areas, like in Anamalazoatra and Vohibola III special reserves, the population density is estimated at 9–13 individuals per square km (.4 sq mile), populations can be 3–5 in some areas and much less in others.
Because they also move quickly—leaping and clinging from one vertical branch to another—observing them in nature is challenging. Their hind limbs are so powerful as to allow them to propel their bodies with great force and leap up to 16 feet (5 m). That’s 20 times their body length. They are not nearly as dexterous, walking on four limbs, or hopping like kangaroos.
Weasel sportive lemurs live in dispersed pairs and males usually have a territory that overlaps with that of a couple of females with whom they mate. Their home range is 2.5–7.5 acres (1-3 ha) on average and they are extremely territorial. Males can engage in fierce fights to defend their turf.
The weasel sportive lemurs scientific name is Lepilemur mustelinus. Lepilemur refers to the sportive lemur genus. Mustelinus in Latin means weasel. These sportive lemurs may be called “weasel” because of their pointy noses.
Ambatovy mine is one of the largest mines in the world. It has the capacity to produce 60,000 tons of nickel and over 5,000 tons of cobalt per year. Ore extraction started in 2011 and is expected to continue for 27 years.
Daily Life and Group Dynamics
Weasel sportive lemurs spend a lot of time resting—probably because metabolizing leaves takes a lot of energy. They shelter in trees, preferring tree holes to branches with dense vegetation. Most weasel sportive lemurs sleep alone, but groupings of a male, female, and baby, or two females, have been observed. Such arrangements are usually composed of a mother and a son or daughter from the previous year, and a youngster.
The tree holes they select are deep with thick walls and approximately 11 feet (3.3 m) above ground. As they enter and leave sleeping sites, they vocalize loudly. They reuse the same sites several months in a row and indicate ownership of it by marking it with their scent glands. They also leave saliva and tooth marks at the entrance before leaving the site to go foraging. As females are bigger than males and more dominant, they usually claim the best sleeping sites for themselves.
Although they spend most of their time alone, groups occasionally congregate before feeding time. Males and females may play, feed, and groom each other for a short time. These social encounters may occur throughout the night.
Because weasel sportive lemurs are nocturnal, most vocalizations are heard in the thick of the night. Their vocal repertoire is elaborate. Two of their main calls are the “ouah” call and the “high-pitched” call. The former are mono-syllabic sounds, the latter are multi-syllabic sounds. Studies of vocalization recordings showed that some notes or syllables uttered by the lemurs are gender-specific. It is likely that they use distinct calls to identify predators.
Besides vocalizations, they also communicate using visual displays, chases, and scent-marking. The latter is typically used to delineate territorial boundaries.
Reproduction and Family
Sportive lemurs are ready to start a family when they are one and a half years old. Females show signs of estrus with a swelling that males are attracted to. They breed once a year, between the months of May and August, and give birth to a single offspring after a gestation of 135 days.
Mothers carry their babies around and park them as they forage for food. They nurse them for 4 months and it takes about one year before youngsters are fully independent.
Weasel sportive lemurs are seed dispersers and because they eat a lot of foliage, they probably contribute to tree pruning and forest clearing.
Conservation Status and Threats
The International Union for Conservation of Nature lists the weasel sportive lemurs as Vulnerable (IUCN, 2022) appearing in the IUCN’s Red List of Threatened Species.
The population of weasel sportive lemurs is declining, and is expected to decline further in the coming years due to the disappearance of suitable habitat. Deforestation, of course, is a major threat. Their populations are severely fragmented. Indeed, Madagascar lost 80% of its forest cover between 1950 and 2000 and with forest fragmentation, the number of edge habitat locations is increasing. Nearly half of Madagascar’s forest is located less than 300 feet (100 m) from the forest edge, which is more susceptible to damage from strong winds, especially during the cyclone season between January and March. Fruiting trees are especially affected, thereby negatively impacting survival chances of other lemur species relying on fruit. Fortunately, such weather events don’t limit the leaves available to weasel sportive lemurs and their population density seems to have remained identical to that of populations living in interior forests.
Deforestation can be caused by climate change induced wildfires, which have been more frequent and more intense than in the past. In fact, scientists estimate that the forests this lemur species inhabits will decrease by 3% in the next thirty years because of climate change events alone.
Human activities also impact ecosystems and biodiversity in many ways. Slash-and-burn agriculture, sugarcane and rice fields, and illegal rosewood logging are some of the most talked about culprits. There are others as well. For instance, mining activities not only destroy the forest, but they also cause soil erosion, vegetation loss, and damage to water quality. They also increase the concentration of minerals in the air, depositing dust on vegetation, which is then ingested by animals, potentially affecting their health. There is now clear evidence that habitat degradation causes lower reproduction rates. Stress on the environment and habitat also makes animals more at risk of illness, especially bacterial infections they may contract when exposed to human populations and livestock, such as E. Coli and Salmonella.
Because mature rainforest is shrinking, it is becoming increasingly more difficult for weasel sporting lemurs to find sleeping sites that provide adequate shelter against predators and harsh weather.
These lemurs fall prey to natural predators such as boas, nocturnal and diurnal raptors (barn owls, Harrier hawks), and the fossa, which is the largest Malagasy carnivore. They are also hunted by humans.
All lemurs are protected under the Convention on International Trade in Endangered Species (CITES), Appendix I. Madagascar is one of the top conservation priorities of the world. This why efforts to preserve biodiversity include programs to monitor the impact of human activities on flora and fauna near exploitation sites in sensitive regions. Ambatovy, one of the largest nickel and cobalt mines in the world, falls under such a plan. Located near the city of Moramanga, the plant and refinery are surrounded by a large forest conservation zone, which is part of the Ambatovy Biodiversity Management System (or ABMS). A subsection of the ABMS includes the Lemur Management Plan which manages 13 species of lemurs endemic to the region, including the weasel sportive lemur.
WWF and other non-profit organizations are actively working with local organizations, governmental agencies, and communities to restore the forest landscape. The purpose of their projects is to plant various indigenous trees in order to prevent soil erosion, protect water sources, and provide food and materials to the Malagasy population. Unfortunately, returning the forests to their original pristine state is not possible. These conservation programs offer training in various farming techniques and give local communities more control over the management of their land.
- IUCN Red List 2020
- Spatial Variations in Eulemur fulvus rufus and Lepilemur mustelinus Densities in Madagascar – Shawn M. Lehman (2007)
- American Journal of Primatology – 70:247-253 (2008) – Sleeping Site Ecology in a Rain-Forest Dwelling Nocturnal Lemur (Lepilemur mustelinus): Implications for Sociality and Conservation – Solofonirina Basoloharijoana, Blanchard Randiranambinina and Elke Zimmermann
- Baseline Health and Nutrition Evaluation of Two Sympatric Nocturnal Lemur Species (Avahi laniger and Lepilemur mustelinus) Residing Near an Active Mine Site at Ambatovy, Madagascar – Randall E. Junge, Cathy Williams, Hajarnirina Rakotondrainibe, Karine Mahefarisoa, Tsiky Rajaonarivelo, Charles Faulkner and Vanessa Mass – Journal of Zoo and Wildlife Medicine
- Food partitioning among Malagasy primates – Jôrg U. Ganzhorn
- Locomotion and postural behavior – M. Schmidt – www.adv-sci-res.net
- wwf.panda.org – Restoring forest landscapes in Madagascar (2018)
Written by Sylvie Abrams, March 2021, Conservation Status updated January 2023