First direct evidence of hibernation in an eastern dwarf lemur species (Cheirogaleus crossleyi) from the high-altitude forest of Tsinjoarivo, central-eastern Madagascar.

The nocturnal dwarf lemurs of Madagascar (genus Cheirogaleus) are the only primates known to be obligate hibernators. Although the physiology of hibernation has been studied widely in the western, small-bodied species, Cheirogaleus medius, no direct evidence of hibernation, i.e., body temperature recordings, has been reported for any of the three recognized eastern dwarf lemur species. We present skin temperature data collected by external collar transmitters from two eastern dwarf lemur individuals (Cheirogaleus crossleyi) captured in the high-altitude forest of Tsinjoarivo, central-eastern Madagascar. Our study species is larger in body size than western dwarf lemurs and inhabits much colder environments. We present the first evidence of hibernation in an eastern dwarf lemur species, and we compare the results with data available for the western species. Although the hibernation period is shorter in dwarf lemurs from Tsinjoarivo, minimum body temperatures are lower than those reported for C. medius. Both individuals at Tsinjoarivo showed limited passive and extended deep hibernation during which they did not track ambient temperature as observed in most western dwarf lemurs. Because ambient temperatures at Tsinjoarivo never exceed 30°C, dwarf lemurs have to experience arousals to maintain homeostasis during periods of hibernation. We show that large dwarf lemurs (>400 g) are capable of undergoing deep hibernation and suggest that cold, high-altitude forests may render hibernation highly advantageous during periods of food scarcity. This study has implications for understanding the physiology of hibernation in small-bodied lemurs.