Summer torpor in African woodland dormice Graphiurus murinus (Myoxidae:Graphiurinae)

We determined the effect of food availability (presence/absence) and ambient temperature (25/10 degrees C) on daily energy expenditure and the use of activity and torpor in summer-acclimated captive Graphiurus murinus. Daily energy expenditure declined logarithmically with duration of food deprivation at a mean rate of 11 and 31% per day at 25 and 10 degrees C, respectively. The incidence of torpor in the presence of food at 25 degrees C was low (one in seven individuals) and increased on a single day's exposure to 10 degrees C and with duration of food deprivation. Use of torpor was highest during the day, varied between individuals, and torpor bouts of greater than 24 h duration were not noted. With food deprivation, individuals at 25 degrees C initially responded by reducing activity but remained euthermic while the same individuals at 10 degrees C responded by increasing their use of torpor during the light period: this difference in response probably reflects a difference in the relative energetic benefits of torpor at different temperatures.