Body temperature and locomotor activity of social subterranean mole voles (Ellobius talpinus) in winter

To find out whether a social subterranean rodent-the northern mole vole (Ellobius talpinus)-hibernates in winter, nine individuals from Southern Siberia were captured in late autumn and implanted with loggers [that constantly recorded body temperature (T_b) and locomotor activity] and then released. Eight of them were recaptured the following spring. From October to April, the animals' T_b never dropped below 33 °C, although cosinor analysis revealed a decrease in mesor values and in the amplitude of daily fluctuations of T_b and activity in winter months. Spectral density of circadian rhythms of both indexes also diminished in winter. The magnitude of T_b and fluctuations of activity differed between the two studied familial groups, probably due to their unequal numbers of individuals, which could affect the total heat production. The levels and patterns of temperature and activity fluctuations observed in winter rule out the possibility of hibernation in this species.