This paper provides a semi-popular account of the discovery that short-beaked echidnas, Tachyglossus aculeatus, hibernate. The discovery was made in Australian Alps, where echidnas with implanted temperature-sensitive transmitters were tracked through winter and found drop their body temperatures close to ambient temperature during winter, with arousals to normal body temperature (about 32oC) every couple of weeks. This is the same pattern shown in northern hemisphere hibernators such as marmots and ground squirrels, and suggests that the capacity for hibernation is an ancient rather than a very advanced characteristic.