Grey mouse-lemur (Microcebus murinus)

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Grey mouse-lemur fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Grey mouse-lemur description

The grey mouse-lemur (Microcebus murinus) is among the smallest living primates, as well as being one of the most primitive primates still alive today ^{(2) (3) (5) (6) (7)}. Despite its tiny size, the grey mouse-lemur is the largest mouse lemur (Microcebus) species, and as its name suggests it has a somewhat mouse-like appearance ⁽³⁾.

The grey mouse-lemur is a greyish-brown animal with a brownish head ^{(2) (3) (8)} bearing two large, protruding ears ^{(2) (3)}. The underparts of the body and the throat are dull beige to off-white, and there is a whitish patch between the eyes ^{(2) (3)}. Some individuals also have dark markings around the eyes ⁽²⁾. The grey mouse-lemur shows no sexual dimorphism, which means that males and females cannot easily be differentiated. Behind the retina of each eye, there is a reflective layer (the ‘tapetum’) that reflects light, making this lemur easy to spot with a torch at night ⁽⁶⁾.

Like other mouse lemurs, the grey mouse-lemur has a relatively long body, a long tail, short legs and a rounded face with large eyes ⁽³⁾.

Also known as

gray mouse lemur, gray mouse-lemur, grey mouse lemur, lesser mouse lemur, lesser mouse-lemur.

French

Microcèbe Murin, Petit Microcèbe.

Spanish

Makisratone.

Size

Head-body length: 12 - 14 cm ^{(2) (3)}

Tail length: 12.5 - 15 cm ⁽³⁾

Weight

40 - 70 g ⁽³⁾

Grey mouse-lemur biology

The grey mouse-lemur is an opportunistic feeder that leaps among the branches and the forest floor, moving about on all fours ^{(2) (3)}. On the ground, the grey mouse-lemur moves in a frog-like fashion, while in the trees it leaps about using its hind legs like a spring ⁽⁶⁾.

Depending on the geographical location, the season and on their respective abundance the grey mouse-lemur will feed on insects, gum, fruits, flowers and even small vertebrates such as frogs, geckos and chameleons ^{(2) (3) (7) (9)}. It will also eat sugary secretions, or ‘honeydew’, produced by the larvae of certain insects, and these secretions may become an important food source for the grey mouse-lemur during the dry season ⁽⁹⁾. The grey mouse-lemur usually feeds solitarily ^{(3) (10)}.

The social organisation of the grey mouse-lemur is quite complex and is referred to as a ‘multi-male/multi-female’ system ^{(2) (10)}. It seems that females compose the nucleus of a population, with some males close to the centre and others scattered around ⁽¹⁰⁾. Each grey mouse-lemur occupies a small home range, with the ranges of all group members overlapping in a central area. The home range of a male grey mouse-lemur is much larger than that of a female, and increases in size during the mating season ^{(2) (3)}.

The grey mouse-lemur is nocturnal ⁽³⁾ and sleeps in a tree hole, dense vegetation or a nest of dead leaves during the day ^{(2) (3)}, often with up to 15 other individuals ⁽³⁾. Each grey mouse-lemur may use between three and nine different tree holes or nests, and typically occupies each one for several consecutive days ^{(2) (3)}. Although males usually sleep alone, males and females may sometimes share a nest during the breeding season ⁽³⁾.

To save energy during periods of inactivity, the grey mouse-lemur may enter into a so-called state of daily torpor, which is characterised by a drop in body temperature ^{(2) (3) (7)}. During the wet season, when temperatures are higher and more food is available, this species is more active, and it will also breed during this time. In contrast, during the cooler dry season there is no sexual activity and the grey mouse-lemur may undergo more extended periods of torpor, living off fat reserves it has accumulated ^{(2) (3) (7) (9)}.

The activity levels of this species vary between populations, with some not showing seasonal torpor while in others females may become totally inactive and remain dormant in their nest holes for up to five months ^{(2) (3)}. Males rarely remain inactive for more than a few days, and become fully active again before the females ⁽³⁾.

The breeding season of the grey mouse-lemur runs from September to March ⁽³⁾, and this species is thought to have a promiscuous mating system ⁽⁵⁾. Interestingly, the female has a specific high-frequency call that she uses when she is ready to mate ^{(3) (10)}. The female grey mouse-lemur typically gives birth to twins after a gestation period of around 60 days ^{(2) (3) (11)}, and may produce two litters each year ^{(2) (11)}.

Young grey mouse-lemurs become independent within about two months, and are able to begin breeding in their first year of life ^{(2) (3) (11)}. Related female grey mouse-lemurs tend to remain in the same area after reaching maturity, whereas males move away from the area in which they were born ^{(2) (3)}. This species may live for 3 to 4 years in the wild, but can survive for up to 14 years in captivity ⁽¹¹⁾. In the wild it faces a range of predators, including birds of prey, owls, mammals such as mongooses, and snakes ⁽³⁾.

Grey mouse-lemur range

Like all lemurs, the grey mouse-lemur is endemic to Madagascar. This species inhabits the western coasts and lowlands of Madagascar ^{(1) (2) (3) (8)}, and a separate population is also found in south-eastern Madagascar ^{(1) (2) (3)}.

Grey mouse-lemur habitat

The grey mouse-lemur is mostly found in drier coasts, in spiny or deciduous forests as well as semi-arid thorn scrub and secondary forest, including plantations ^{(1) (2) (3)}. It has been found at elevations from sea level to about 800 metres ⁽²⁾.

This species rests in tree holes ^{(1) (2) (3)}, with females often sharing the same hole whereas males tend to sleep on their own ^{(2) (3) (6)}. The grey mouse-lemur uses all levels of the forest to feed, from the ground to the canopy ⁽⁹⁾, although it tends to prefer the lower levels and understorey where the vegetation is dense ⁽³⁾.

Grey mouse-lemur status

The grey mouse-lemur is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾ and is listed on Appendix I of CITES ⁽⁴⁾.

Grey mouse-lemur threats

As it is a widespread, common species and readily adapts to changing environments, the grey mouse-lemur currently faces no major threats and is not believed to be at risk of extinction ⁽¹⁾. It is thought to be one of Madagascar’s most abundant small mammals ^{(1) (2)}, and is one of the least threatened of all lemur species ⁽¹⁾.

However, given the large scale of habitat loss across its range, mainly due to agriculture and cattle grazing, the grey mouse-lemur population is likely to be declining ⁽¹⁾. This species is also sometimes captured for the pet trade ^{(1) (2)}.

Although clearance of forests may reduce the number of available tree holes in which the grey mouse-lemur can live, some individuals have been seen to nest in plantations and other secondary forest habitats ⁽¹⁾. However, there is evidence to suggest that reduced habitat quality can have impacts on its populations, with fewer tree holes meaning fewer opportunities for individuals to conserve energy through periods of torpor. This is likely to reduce survival rates, and may explain why these lower-quality habitats support lower densities of this species ⁽¹²⁾.

Grey mouse-lemur conservation

The grey mouse-lemur is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), meaning that international trade in this species is prohibited ⁽⁴⁾. This small lemur occurs in a number of protected areas throughout its range ^{(1) (2)}, and is also bred in captivity ^{(1) (13)}.

Find out more

Find out more about the grey mouse-lemur and other mouse lemur species:

• BBC Nature - Grey mouse lemur:
  http://www.bbc.co.uk/nature/life/Gray_Mouse_Lemur
• Primate Info Net - Mouse lemur:
  http://pin.primate.wisc.edu/factsheets/entry/mouse_lemur

More information on conservation in Madagascar:

• MadagascarWildlife Conservation:
  http://www.mwc-info.net/en/
• Madagascar Fauna Group:
  http://www.savethelemur.org/
• Madagasikara Voakajy:
  http://www.madagasikara-voakajy.org/
• Lemur Conservation Foundation:
  http://www.lemurreserve.org/

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Glossary

Deciduous forest

Forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Gestation

The state of being pregnant; the period from conception to birth.

Home range

The area occupied by an animal during routine activities, which is not actively defended.

Honeydew

A sugar-rich secretion produced by aphids and some scale insects that feed on plant sap.

Larvae

Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Nocturnal

Active at night.

Promiscuous

Mating with more than one individual without forming any permanent bonds.

Secondary forest

Forest that has re-grown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.

Sexual dimorphism

When males and females of the same species differ in appearance.

Torpor

A sleep-like state in which the body processes slow to a fraction of their normal rate.

Vertebrates

Animals with a backbone, including mammals, birds, reptiles, amphibians and fish.

References

1. IUCN Red List (December, 2012)
   http://www.iucnredlist.org/
2. Mittermeier, R.A., Konstant, W.R., Hawkins, F., Louis, E.E., Langrand, O., Ratsimbazafy, J., Rasoloarison, R., Ganzhorn, J.U., Rajaobelina, S., Tattersall, I. and Meyers, D.M. (2006) Lemurs of Madagascar. Second Edition. Conservation International, Washington, DC.
3. Garbutt, N. (2007) Mammals of Madagascar: A Complete Guide. A&C Black Publishers, London.
4. CITES (February, 2013)
   http://www.cites.org/
5. Fietz, J. (1999) Mating system of Microcebus murinus. American Journal of Primatology, 48: 127-133.
6. Martin, R.D. (1973) A review of the behaviour and ecology of the lesser mouse lemur. In: Michael, R.P. and Crook, J.H. (Eds.) Comparative Ecology and Behaviour of Primates. Academic Press, London.
7. Perret, M. and Aujard, F. (2001) Daily hypothermia and torpor in a tropical primate: synchronization by 24-h light-dark cycle. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, 281: R1925-R1933.
8. Yoder, A.D., Rasoloarison, R.M., Goodman, S.M., Irwin, J.A., Atsalis, S., Ravosa, M.J. and Ganzhorn, J.U. (2000) Remarkable species diversity in Malagasy mouse lemurs (primates, Microcebus). PNAS, 97(21): 11325-11330.
9. Dammhahn, M. and Kappeler, P.M. (2008) Comparative feeding ecology of sympatric Microcebus berthae and M. murinus. International Journal of Primatology, 29: 1567-1589.
10. Radespiel, U. (2000) Sociality in the gray mouse lemur (Microcebus murinus) in northwestern Madagascar. American Journal of Primatology, 51: 21-40.
11. Bons, N., Rieger, F., Prudhomme, D., Fisher, A. and Krause, K.H. (2006) Microcebus murinus: a useful primate model for human cerebral aging and Alzheimer’s disease? Genes, Brain and Behavior, 5: 120-130.
12. Ganzhorn, J.U. and Schmid, J. (1998) Different population dynamics of Microcebus murinus in primary and secondary deciduous dry forests of Madagascar. International Journal of Primatology, 19(5): 785-796.
13. The Species Survival Network (2000) Summary of the Status of Wild Populations of Species Listed on CITES Appendix I and the Difficulty of Keeping or Breeding Specimens of these Species in Captivity. Prepared in response to CITES Secretariat Notification to the Parties No. 2000/044 by The Species Survival Network, Washington. Available at:
    http://www.cites.org/common/com/ac/16/E16-Inf-15.pdf