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Reproductive Biology of Mouse and Dwarf Lemurs of Eastern Madagascar, With an Emphasis on Brown Mouse Lemurs (Microcebus rufus) at Ranomafana National Park, A Southeastern Rainforest

This dissertation investigates reproductive schedules of brown mouse lemurs at Ranomafana, using intensive trapping techniques. The reproductive condition of female mouse lemurs was recorded on the basis of vaginal morphology, vaginal smears, body mass gain profiles and nipple development. Testis size was measured in males throughout the reproductive season. The timing of the first seasonal estrus was determined in frequently captured females over multiple years and it showed individual periodicities close to 365 days, consistent with endogenous regulation and entrainment by photoperiod. The timing of estrus did not correlate with female age or body mass. Males showed testicular regression during the rainy season, although there was high inter-individual variation in testes size at any given point during the reproductive season. Furthermore, some individuals completed testicular regression earlier than others. Implications for polyestry are discussed. For comparative purposes, mouse lemurs were also trapped at two study sites in the Tsinjoarivo area: one in a forest fragment and the other within continuous forest. These forests are higher in altitude than the main study area at Ranomafana. Trapping success for mouse lemurs was lower at Tsinjoarivo than Ranomafana. Albeit preliminary, data from Tsinjoarivo suggest that females have lower reproductive success than do females at Ranomafana. Nevertheless, mouse lemurs in the Tsinjoarivo forest fragment did not appear to be in "poorer" condition than those in the continuous forest. It had been reported in the literature that western gray mouse lemurs captured in secondary forests have lower body masses and lower recapture rates than those captured in primary forest; in fact, the opposite was true of the mouse lemurs at Tsinjoarivo. I additionally collected data on a larger member of the family Cheirogaleidae, the dwarf lemurs (Cheirogaleus), which live in sympatry with Microcebus at Ranomafana and Tsinjoarivo. I analyzed the patterns of growth, development and reproduction in Cheirogaleus and Microcebus and compared dwarf and mouse lemurs to other similarly-sized prosimians which do not undergo torpor or hibernation. These comparisons draw attention to the unusual reproductive and metabolic strategies employed by cheirogaleids to cope with Madagascar's unpredictable environments, which ultimately define their very unique life histories.
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