Body temperature, heart rate and oxygen consumption of normothermic and heterothermic western jumping mice (Zapus princeps).

1. Heart rates and oxygen consumption were measured for normothermic, hibernating, and arousing Zapus princeps. 2. Rectal and oral body temperature were monitored and differential rates of rewarming of the body were recorded. 3. Lengths of periodic arousals differ in two stages of hibernation; days 50-80 arousal durations were 12 hr, 43 min while days 140-210 were 10 hr, 28 min. 4. Total energy budget of hibernation was calculated for a 295 day hibernation cycle based on the utilization of 18,020 cc of oxygen for that period. The calculated utilization of fat would be 8.97 g while the observed use was 9.5-11.1 g.