Abstract
When Syrian hamsters (Mesocricetus auratus) are bred in a cold and short-day environment, most animals go into hibernation after a certain period of time. However, to date it has not been possible to predict which hamster will enter hibernation. In this study, we subcutaneously implanted thermo-loggers in hamsters bred in the cold environment, and recorded the subcutaneous temperature at short intervals until they went into hibernation. A time series analysis of temperature disclosed that a fall of 0.4 to 0.8°C in subcutaneous temperature was seen 5 to 16 days before entering hibernation, and this phenomenon continued for three days or more. No hamster went into the hibernation without displaying this signal. Although the mechanism by which this phenomenon takes place is not clear, it is a sign from the body, which is useful for indicating if a hamster will enter hibernation shortly.
