Microcebus murinus inhabits lowland tropical dry forest, sub-arid thorn scrub, gallery forest, spiny forest and secondary forest formations from sea level to 800 m, and is one of Madagascar’s most abundant small native mammals (Radespiel, 2000). Studies at Ankarafantsika indicate that individuals may take shelter in three to nine different tree holes within their range and remain in a given shelter for several days in succession. Females tend to share nests with several conspecifics, while males tend to sleep alone (Radespiel et al., 1998). Two or more females will form breeding groups and raise their young cooperatively (Eberle and Kappeler, 2006). The diet is varied, consisting largely of invertebrates (particularly beetles), but also fruits, flowers, gums, nectar, and small amphibians and reptiles. The Long-eared Owl (Asio madagascariensis) is an important predator of this species (Goodman et al., 1993a). Activity patterns appear to differ between populations and sexes. Males and females at Ankarafantsika exhibit daily, rather than seasonal, torpor (Zimmermann, 1998). At the Kirindy Forest both sexes show the same daily torpor, but most adult females also hibernate for significant periods, while males remain active during these same periods. In fact, the males become extremely active several weeks before the females emerge from their torpor (Schmid and Kappeler, 1998; Rasoazanabary, 2001; Génin, 2003). Recent studies of gray mouse lemur social behavior confirm that male home ranges tend to be twice as large as those of females, and also increase in size during the mating season (Buesching et al., 1998; Radespiel, 2000; Eberle and Kappeler, 2002). Ranges of both sexes overlap, those of females less so than those of males, while the ranges of all members of a “neighborhood” overlap in a central area. Recent genetic studies of M. murinus populations at Kirindy suggest that females tend to arrange themselves spatially in clusters of related individuals, while males tend to emigrate from their natal groups (Wimmer et al., 2002). The mating system is characterized as multi-male/multi-female (Radespiel, 2000; Eberle and Kappeler, 2002, 2004). Females become receptive every 45–55 days from September to March, during which time the male’s testes increase greatly in size. Typically, two young are born after a gestation of approximately 60 days. Although M. murinus is reported to inhabit secondary forests and degraded habitats, at least one recent study suggests that decreased habitat quality may have adverse effects on population dynamics. According to Ganzhorn and Schmid (1998), fewer large tree holes in secondary forests result in fewer opportunities to save energy through periods of torpor, and may increase levels of stress and mortality.
