Effects of Sex and Age on Heterothermy in Goodman’s Mouse Lemur (Microcebus lehilahytsara)

All habitats of Madagascar go through a dry season from April to September each year, resulting in a period of fruit scarcity lasting up to 6 months and creating selection pressure for adaptation to fluctuations in resources. Some Cheirogaleid lemurs, including mouse lemurs (Microcebus), use daily torpor and long-term hibernation during this period, saving energy through inactivity. Capture–recapture studies in some mouse lemur populations have suggested a pattern of biased sex ratio throughout the winter as a result of females hibernating while most males remain active. We studied winter activity in a captive population of Microcebus lehilahytsara, Goodman’s mouse lemur, in a large enclosure at Zoo Zürich, Switzerland using capture–recapture methods to determine how this behavior varies with sex and age, and what this pattern suggests about the ultimate cause of torpor use in this clade. Our results suggest that Goodman’s mouse lemurs use torpor to avoid seasonal food shortage, even though they experience less extreme seasonal variability of food availability than western dry forest mouse lemurs. Male and female Goodman’s mouse lemurs are equally capable of winter torpor, and most remaining active individuals are young that have not sufficiently fattened. This suggests that the “ideal” winter behavior for both males and females is torpor, which ultimately avoids periods of seasonal food scarcity.