THERMOREGULATION AND TORPOR IN AFRICAN WOODLAND DORMICE, GRAPHIURUS-MURINUS, FOLLOWING COLD-ACCLIMATION

Studied thermoregulation of 3 adult woodland dormice (Graphiurus murinus) following acclimation to 15-degrees-C and 10-degrees-C. The dormice entered hibernation under these conditions characterised by a fall in body temperature to within 1-degrees-C of ambient, and a prolonged reduction in oxygen consumption measured over 24 h at 10-degrees-C and 5-degrees-C. Non-shivering thermogenic capacity exceeded that required to re-attain homeothermy by 20%, but would permit these dormice to maintain normothermia down to -5-degrees-C. The cycle of body mass displayed by G. murinus in the present study is characteristic of hibernating temperate dormice, but was not observe in specimens collected throughout the year in southern Africa. It therefore appears that woodland dormice may not enter hibernation throughout their distribution during winter, but may exhibit facultative torpor under adverse climatic conditions.