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Microcebus rufusbrown mouse lemur

By Matthew Esser

Geographic Range

The range of brown mouse lemurs (Microcebus rufus) includes areas of northern and eastern Madagascar in areas of tropical rainforests and deciduous forests. Brown mouse lemurs can be found in the many protected areas of Madagascar including: Montagne d’ Ambre National Park, Ranomafana National Park, Marojeiy Nature Reserve, and Zahamena Nature Reserve (Harcourt and Thornback, 1990). (Harcourt and Thornback, 1990)

Habitat

Microcebus rufus inhabits primary and secondary forested habitats, including forest fringes of the coastal rainforests and secondary bamboo forests (Macdonald, 1984). (Macdonald, 1984)

Physical Description

Brown mouse lemurs are reddish brown to pale brown dorsally, and white to cream on the underside. The pelage is soft. Between the eyes and down the nose, there is a white or cream colored stripe. The cheeks are brownish-red. The ears are medium sized and membranous with well-developed facial and carpal vibrissae (Macdonald, 1984; Rowe, 1996).

Head and body length is 12.5 cm. Tail length is 11.5 cm. These animals weigh around 50 g, although weights are higher in February and March (Mittermeier et al., 1994). (Macdonald, 1984; Mittermeier, 1994; Rowe, 1996)

  • Range mass
    39 to 98 g
    1.37 to 3.45 oz
  • Average mass
    50 g
    1.76 oz
  • Average length
    12.5 cm
    4.92 in

Reproduction

This species has a ritualistic courtship before breeding which consists of the males using soft squeak calls and tail-lashing to get the female to copulate. Females alert males to their sexual receptivity through frequent ano-genital rubbing and mouth wiping. Females use threat calls to signal to the males that mating is complete (Perret, 1992).

Male territories overlap with those of several females. Dominant males may mate with several females, making a loose sort of harem. (Perret, 1992)

Brown mouse lemurs mate between September and October. Females experience an estrous cycle lasting an average of twenty days. The gestation period is approximately 60 days. Young are generally born in November and December, with 1 to 3 offspring per litter. Weaning occurs around 2 months of age, so females may produce 2 litters per year in captivity. Sexual maturity is reached after one year of age.

Developing offspring begin to play with their mother, chasing her and jumping on her hands and feet. This may function to help them develop their locomotion skills.

During the months of winter following their birth, the males of the species leave the areas which they were born (Nowak, 1999). (Nowak, 1999)

  • Breeding interval
    Breeding in captivity can take place twice per year.
  • Breeding season
    Breeding occurs during September and October, births occur in November and December.
  • Range number of offspring
    1 to 3
  • Average number of offspring
    2.5
    AnAge
  • Average gestation period
    2 months
  • Average gestation period
    61 days
    AnAge
  • Average weaning age
    2 months
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

In the three weeks following birth the offspring remain confined to the nest. The mother exhibits extreme commitment to new infants, leaving the nest only to defecate, urinate, feed, or drink. The offspring are dependent for about 2 months, and then they are weaned and able to survive on their own. Weaning begins at the end of February when food is readily available.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Lifespan in brown mouse lemurs is 6 to 8 years in the wild, but when they are in captivity they can reach 10 to 15 years with an average of 12 years in males (Nowak, 1999). (Nowak, 1999)

Behavior

Brown mouse lemurs are strictly nocturnal. They sleep in tree holes during the day or they make nests in large groups consisting of females and their dependent offspring. From the months of May through September, torpor is exhibited by this species. During this period they can experience a loss of 5 to 35 g in body weight with a reduction in tail circumference from 4 to 12 mm. The tail loses its circumference because it is a major fat reservoir for these animals and during torpor they deplete these reserves. Females usually remain in torpor longer than males (Glaston, 1979).

Brown mouse lemurs also have an extended harem system and exhibit limited polygyny. Male territories are about 200 meters in diameter and will overlap at least two female territories. The home ranges of females are slightly smaller than those of the males. Subdominant males may be found on the periphery of the dominant male territories (Glaston, 1979). (Glaston, 1979)

Communication and Perception

As in all primates, these lemurs are likely to use a variety of modes of communication. Scent marking is important in advertising estrus, as are the visual signals of touching the genitals and wiping the mouth. Tactile communication is important during mating, as are vocalizations, which let the male know when the female is done. (Nowak, 1999)

Food Habits

Brown mouse lemurs are primarily frugivorous, although they also consume insects, young leaves, flowers, gum, and possibly nectar and pollen. Diet varies seasonally with an increase in fruit consumption during the months of December to March. The largest portion of the diet is made up of the fruits produced by plants in the mistletoe genus Bakerella. This genus of plants is foraged upon because of its high fiber and fat content, and is important to build up fat reserves before lemurs enter the season in which they experience torpor.

These animals also consume large insects. They have been found to eat scarab beetles which are 4.5 x 2.5 cm. They also appear to be attracted to flowering trees both for the nectar and for the pollinating insects (Atsalis, 1998). (Atsalis, 1998)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • fruit
  • nectar
  • pollen
  • flowers
  • sap or other plant fluids

Predation

Brown mouse lemurs are preyed upon by raptors, small mammalian predators, humans, domestic dogs, and cats (Goodman et al. 1993). (Goodman, 1993)

Ecosystem Roles

Brown mouse lemurs are likely to be important in dispersing seeds of the fruits they consume. To the extent that they serve as prey for other animals, they may impact predator populations.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Brown mouse lemurs, along with other components of the unique, native Malagasy fauna, contribute to ecotourism in Madagascar.

Economic Importance for Humans: Negative

There are adverse effects of brown mouse lemurs on humans.

Conservation Status

Because of the rate of deforestation on Madagascar, all mouse lemur species are considered at risk by CITES. However, brown mouse lemurs are one of the few native Malagasy primates that are still relatively common throughout their range.

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Matthew Esser (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Atsalis, S. 1998. Feeding Ecology and Aspects of Life History in *Microcebus rufus* (Family Cheirogaleidae). New York City: University of New York.

Fleagle, J. 1988. Primate Adaptation and Evolution. New York City: Academic Press.

Glaston, A. 1979. Reproduction and Behavior of the Russet Mouse Lemur (*Microcebus rufus*) in captivity. University of London: Unpublished PhD. Thesis.

Goodman, S. 1993. A review of predation on lemurs: Implications for the evolution of social behavior in small nocturnal primates. Pp. 1-5 in P Kappeler, J Ganzhorn, eds. Lemur Social Systems and Their Ecological Basis. New York: Plenum Publishing Corporation.

Harcourt, C., J. Thornback. 1990. Lemurs of Madagascar and the Comoros. The IUCN Red Data Book. Gland, Switzerland, and Cambridge, U.K.: IUCN.

Macdonald, D. 1984. The Encyclopedia of Mammals. New York, NY: Facts on File, Inc..

Martin, R. 1972. A preliminary field-study of the lesser mouse lemur (*Microcebus rufus* J.F. Miller 1777). Advances in Ethology, 9: 43-89.

Mittermeier, R. 1994. The Lemurs of Madagascar. Conservation International.

Nowak, R. 1999. Walkers Mammals of the World. Baltimore and London: The John Hopkins University Press 6th edition Vol. 1.

Perret, M. 1992. Environmental and Social Determinants of Sexual Function in the Male Lesser Mouse Lemur (*Microcebus*). Folia Primatologica, 59: 1-25.

Rowe, N. 1996. The Pictorial Guide to the Living Primates. East Hampton, New York: Pogonias Press.

Wisconsin Regional Primate Research Center: Primate Info Net, November 27, 2001. "Russet Mouse Lemur (Microcebus rufus)" (On-line). Accessed August 29, 2002 at http://www.primate.wisc.edu/pin/factsheets/microcebus_rufus.html.

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