FAT-TAILED DWARF LEMUR
Geographic Distribution and Habitat
The fat-tailed dwarf lemur, also known as lesser dwarf lemurs, or western fat-tailed dwarf lemurs, is endemic to the dry deciduous forests of western Madagascar.
Madagascar experiences a hot, wet season from November to April, and a cool, dry season from May to October. During the dry season, water is extremely scarce on the island, an environmental factor that has contributed to the unique adaptations of the fat-tailed dwarf lemur.
Size, Weight, and Lifespan
Fat-tailed dwarf lemurs have unusually long lifespans: up to 18 years in captivity. In the wild, they usually live between 4 and 11 years.
They weigh between 4 and 10 oz (120–270 g) and are heaviest just before entering their hibernation-like state of torpor. Their head and body length is about 8–9 in (20–23 cm), with the tail adding another 8–11 in (20–27 cm) in length.
Fat-tailed dwarf lemurs are a brown-gray or brown-red color, with white undersides. Their eyes are large and are framed by dark rings. As their name suggests, their tails are fatter than other lemur species’. This is because the fat-tailed dwarf lemur uses its tail to store fat as energy reserves during lean times, not unlike a camel’s hump.
What Does It Mean?
A living arrangement between an adult male and an adult female that does not necessarily describe the sexual interactions or reproduction between monogamous pairs; rather it refers to their their living conditions. The arrangement consists of, but is not limited to: sharing territory; obtaining food resources; and raising offspring.
A sleep-like state in which the body decreases physiological activity.
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Fat-tailed dwarf lemurs are largely frugivorous (fruit-eating), although they also eat nectar, seeds, flowers, insects, and small vertebrates. During the wet season, when food is abundant, the lemur eats large amounts of food, increasing his body weight by about 40% at a time. Right before entering torpor, the fat-tailed dwarf lemur’s diet is composed almost entirely of fruit.
Behavior and Lifestyle
Fat-tailed dwarf lemurs are nocturnal, sleeping during the day and foraging for food alone at night. During the day, they often sleep in hollow trees cushioned with dead leaves, alone or in groups of up to five. They spend virtually all day, every day of their lives in trees.
Fat-tailed dwarf lemurs are the only known primate species to engage in long-term torpor. Torpor is a hibernation-like state of inactivity, which allows the fat-tailed dwarf lemur to survive the long periods of food and water scarcity during the dry season. During this time, the lemur burns through his energy reserves much more slowly than when he is active. He spends torpor curled up in a ball, often in a hollow tree, surviving on the fat stored in his tail. He enters torpor in May, and often does not emerge until the beginning of the wet season in November.
During torpor, the fat-tailed dwarf lemur’s heart beats just four times per minute, and it takes a breath only every 10 to 15 minutes.
Fat-tailed dwarf lemurs live in small family groups consisting of a bonded pair and their offspring from the past one or two litters. They are socially monogamous, and only find another partner when their own dies. They cohabitate, often sharing the same tree hole to sleep in and sharing in child-rearing duties; however, the female may also mate with males other than her bonded partner.
Their main predators include fossas (a carnivorous mammal related to the mongoose), predatory birds, and snakes. They are not completely helpless against these predators, however. They hide from large predators in tree hollows, and despite their relatively small size, they can effectively attack snakes to protect themselves and their young.
Fat-tailed dwarf lemurs are relatively quiet. They sometimes emit a short call to contact others and can let out a loud cry when threatened. They also smear feces on trees to mark their territory.
Fat-tailed dwarf lemurs become sexually mature when they are about two years of age, although they won’t start to breed until after they’ve left their parents and established their own territory, usually not until the age of three. They typically begin mating when they emerge from their dry-season torpor between September and November. Babies are born in December or January, after a 61–64-day gestation. Twins are most common, although they can bear between one and four babies at a time.
Normally, fat-tailed dwarf lemurs only breed every other year. About 40% of a female’s offspring are fathered by a male other than her mate, an unusually high rate. Males help with caring for young, even ones that were fathered by a different male. When infants are first born, the male and female take turns leaving the tree hollow to forage at night, with the other staying behind to guard the babies. As the babies get older, their parents spend increasingly less time guarding them until they are ready to forage for themselves.
Fat-tailed dwarf lemurs help to pollinate some species of baobab trees. They also help to disperse seeds of the many plants they eat, and their scent-marking routine involving the smearing of feces on trees provides the microclimate that various species of parasitic plants need to germinate. They are also an important food source for many of Madagascar’s medium-sized carnivores, many of which are threatened or endangered themselves.
The fat-tailed dwarf lemur is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2018), appearing on the IUCN Red List of Threatened Species. Their geographic distribution is now considered to be constrained to western dry deciduous forests of Madagascar. That region has been undergoing unprecedented rates of deforestation. As a result, it is very likely the species is currently in decline. In addition, a future decline of 30% is anticipated due to decline in habitat quality and potential exploitation. Further information on population status, and threats may warrant listing this species in a more threatened category in the future.
The fat-tailed dwarf lemur is primarily threatened by habitat loss and habitat fragmentation. Specifically, practices such as slash-and-burn agriculture, charcoal production, and brushfires pose threats to the species. While they are currently relatively abundant, their population is in decline.
Fat-tailed dwarf lemurs, like all dwarf and mouse lemurs, are listed under Appendix I of the Convention on International Trade in Endangered Species (CITES), which significantly restricts trade of this species.
- Blanco, M. B. and S. M. Zehr. 2015. Striking longevity in a hibernating lemur. Journal of Zoology 296(3).
- Fietz, J., H. Zischler, C. Schwiegk, J. Tomiuk, K. H. Dausmann, J. U. Ganzhorn. 2000. High rates of extra-pair young in the pair-living fat-tailed dwarf lemur, Cheirogaleus medius. Behavioral Ecology and Sociobiology 49(1):8-17.
- Dausmann, K.H. 2010. Effective predation defence in Cheirogaleus medius. Lemur News 15.
Written by K. Clare Quinlan, July 2019